Publications

Title / Authors / Details Open Access Download

Autophagosome biogenesis machinery.
Walker SA, Ktistakis NT

We review current knowledge of the process of autophagosome formation with special emphasis on the very early steps: turning on the autophagy pathway, assembling the autophagy machinery, and building the autophagosome. The pathway is remarkably well co-ordinated spatially and temporally, and it shows broad conservation across species and cell types, including neurons. In addition, although much current knowledge derives mostly from settings of non-selective autophagy, recent work also indicates that selective autophagy, and more specifically mitophagy, shows similar dynamics. Having an understanding of this remarkable process may help the design of novel therapeutics for neurodegeneration and other pathologies.

+ View Abstract

Journal of molecular biology, , 1089-8638, , 2019

PMID:31705882

Targeting of early endosomes by autophagy facilitates EGFR recycling and signalling.
Fraser J, Simpson J, Fontana R, Kishi-Itakura C, Ktistakis NT, Gammoh N

Despite recently uncovered connections between autophagy and the endocytic pathway, the role of autophagy in regulating endosomal function remains incompletely understood. Here, we find that the ablation of autophagy-essential players disrupts EGF-induced endocytic trafficking of EGFR. Cells lacking ATG7 or ATG16L1 exhibit increased levels of phosphatidylinositol-3-phosphate (PI(3)P), a key determinant of early endosome maturation. Increased PI(3)P levels are associated with an accumulation of EEA1-positive endosomes where EGFR trafficking is stalled. Aberrant early endosomes are recognised by the autophagy machinery in a TBK1- and Gal8-dependent manner and are delivered to LAMP2-positive lysosomes. Preventing this homeostatic regulation of early endosomes by autophagy reduces EGFR recycling to the plasma membrane and compromises downstream signalling and cell survival. Our findings uncover a novel role for the autophagy machinery in maintaining early endosome function and growth factor sensing.

+ View Abstract

EMBO reports, , 1469-3178, , 2019

PMID:31448519

Open Access

Selective Autophagy of Mitochondria on a Ubiquitin-Endoplasmic-Reticulum Platform.
Zachari M, Gudmundsson SR, Li Z, Manifava M, Shah R, Smith M, Stronge J, Karanasios E, Piunti C, Kishi-Itakura C, Vihinen H, Jokitalo E, Guan JL, Buss F, Smith AM, Walker SA, Eskelinen EL, Ktistakis NT

The dynamics and coordination between autophagy machinery and selective receptors during mitophagy are unknown. Also unknown is whether mitophagy depends on pre-existing membranes or is triggered on the surface of damaged mitochondria. Using a ubiquitin-dependent mitophagy inducer, the lactone ivermectin, we have combined genetic and imaging experiments to address these questions. Ubiquitination of mitochondrial fragments is required the earliest, followed by auto-phosphorylation of TBK1. Next, early essential autophagy proteins FIP200 and ATG13 act at different steps, whereas ULK1 and ULK2 are dispensable. Receptors act temporally and mechanistically upstream of ATG13 but downstream of FIP200. The VPS34 complex functions at the omegasome step. ATG13 and optineurin target mitochondria in a discontinuous oscillatory way, suggesting multiple initiation events. Targeted ubiquitinated mitochondria are cradled by endoplasmic reticulum (ER) strands even without functional autophagy machinery and mitophagy adaptors. We propose that damaged mitochondria are ubiquitinated and dynamically encased in ER strands, providing platforms for formation of the mitophagosomes.

+ View Abstract

Developmental cell, , 1878-1551, , 2019

PMID:31353311

Open Access

Autophagy, Inflammation, and Metabolism (AIM) Center in its second year.
Deretic V, Prossnitz E, Burge M, Campen MJ, Cannon J, Liu KJ, Liu M, Hall P, Sklar LA, Allers L, Mariscal L, Garcia SA, Weaver J, Baehrecke EH, Behrends C, Cecconi F, Codogno P, Chen GC, Elazar Z, Eskelinen EL, Fourie B, Gozuacik D, Hong W, Jo EK, Johansen T, Juhász G, Kimchi A, Ktistakis N, Kroemer G, Mizushima N, Münz C, Reggiori F, Rubinsztein D, Ryan K, Schroder K, Shen HM, Simonsen A, Tooze SA, Vaccaro M, Yoshimori T, Yu L, Zhang H, Klionsky DJ

The NIH-funded center for autophagy research named Autophagy, Inflammation, and Metabolism (AIM) Center of Biomedical Research Excellence, located at the University of New Mexico Health Science Center is now completing its second year as a working center with a mission to promote autophagy research locally, nationally, and internationally. The center has thus far supported a cadre of 6 junior faculty (mentored PIs; mPIs) at a near-R01 level of funding. Two mPIs have graduated by obtaining their independent R01 funding and 3 of the remaining 4 have won significant funding from NIH in the form of R21 and R56 awards. The first year and a half of setting up the center has been punctuated by completion of renovations and acquisition and upgrades for equipment supporting autophagy, inflammation and metabolism studies. The scientific cores usage, and the growth of new studies is promoted through pilot grants and several types of enablement initiatives. The intent to cultivate AIM as a scholarly hub for autophagy and related studies is manifested in its Vibrant Campus Initiative, and the Tuesday AIM Seminar series, as well as by hosting a major scientific event, the 2019 AIM symposium, with nearly one third of the faculty from the International Council of Affiliate Members being present and leading sessions, giving talks, and conducting workshop activities. These and other events are often videostreamed for a worldwide scientific audience, and information about events at AIM and elsewhere are disseminated on Twitter and can be followed on the AIM web site. AIM intends to invigorate research on overlapping areas between autophagy, inflammation and metabolism with a number of new initiatives to promote metabolomic research. With the turnover of mPIs as they obtain their independent funding, new junior faculty are recruited and appointed as mPIs. All these activities are in keeping with AIM's intention to enable the next generation of autophagy researchers and help anchor, disseminate, and convey the depth and excitement of the autophagy field.

+ View Abstract

Autophagy, 15, 1554-8635, , 2019

PMID:31234750

Who plays the ferryman: ATG2 channels lipids into the forming autophagosome.
Ktistakis NT

Expansion of the autophagosomal membrane requires a mechanism to supply lipids while excluding most membrane proteins. In this issue, Valverde et al. (2019. https://doi.org/10.1083/jcb.201811139) identify ATG2, a member of the autophagy-related protein family, as a lipid transfer protein and provide important novel insights on how autophagosomes grow.

+ View Abstract

The Journal of cell biology, , 1540-8140, , 2019

PMID:31076453

ER platforms mediating autophagosome generation.
Ktistakis NT

The origin of the autophagosomal membrane started to be debated by scientists working in the field within one year of the modern definition of autophagy in 1963. There is now converging evidence from older and newer studies that the endoplasmic reticulum is involved in formation of autophagosomes. Thus, it is possible to trace from early morphological work - done without the benefit of molecular descriptions - to recent studies - dissecting how specific proteins nucleate autophagosome biogenesis - a long series of experimental findings that are beginning to answer the 55-year old question with some confidence. The view that has emerged is that specialised regions of the endoplasmic reticulum, in dynamic cross talk with most intracellular organelles via membrane contact sites, provide a platform for autophagosome biogenesis.

+ View Abstract

Biochimica et biophysica acta. Molecular and cell biology of lipids, , 1879-2618, , 2019

PMID:30890442

Phosphorylation of Syntaxin 17 by TBK1 Controls Autophagy Initiation.
Kumar S, Gu Y, Abudu YP, Bruun JA, Jain A, Farzam F, Mudd M, Anonsen JH, Rusten TE, Kasof G, Ktistakis N, Lidke KA, Johansen T, Deretic V

Syntaxin 17 (Stx17) has been implicated in autophagosome-lysosome fusion. Here, we report that Stx17 functions in assembly of protein complexes during autophagy initiation. Stx17 is phosphorylated by TBK1 whereby phospho-Stx17 controls the formation of the ATG13FIP200 mammalian pre-autophagosomal structure (mPAS) in response to induction of autophagy. TBK1 phosphorylates Stx17 at S202. During autophagy induction, Stx17 transfers from the Golgi, where its steady-state pools localize, to the ATG13FIP200 mPAS. Stx17 was in complexes with ATG13 and FIP200, whereas its non-phosphorylatable mutant Stx17 was not. Stx17 or TBK1 knockouts blocked ATG13 and FIP200 puncta formation. Stx17 or TBK1 knockouts reduced the formation of ATG13 protein complexes with FIP200 and ULK1. Endogenous Stx17 colocalized with LC3B following induction of autophagy. Stx17 knockout diminished LC3 response and reduced sequestration of the prototypical bulk autophagy cargo lactate dehydrogenase. We conclude that Stx17 is a TBK1 substrate and that together they orchestrate assembly of mPAS.

+ View Abstract

Developmental cell, , 1878-1551, , 2019

PMID:30827897

Alpha-synuclein fibrils recruit TBK1 and OPTN to lysosomal damage sites and induce autophagy in microglial cells.
Bussi C, Peralta Ramos JM, Arroyo DS, Gallea JI, Ronchi P, Kolovou A, Wang JM, Florey O, Celej MS, Schwab Y, Ktistakis NT, Iribarren P

Autophagic dysfunction and protein aggregation have been linked to several neurodegenerative disorders, but the exact mechanisms and causal connections are not clear and most work was done in neurons and not in microglial cells. Here we report that exogenous fibrillar but not monomeric alpha-synuclein (AS) induces autophagy in microglial cells. We extensively studied the dynamics of this response by both live-cell imaging and correlative light-electron microscopy (CLEM) and found that it correlates with lysosomal damage and is characterised by the recruitment of the selective autophagy-associated proteins TANK-binding kinase 1 (TBK1) and Optineurin (OPTN) to ubiquitinated lysosomes. In addition, we observed that LC3 recruitment to damaged lysosomes was dependent on TBK1 activity. In these fibrillar AS-treated cells, autophagy inhibition impairs mitochondrial function and leads to microglial cell death. Our results suggest that microglial autophagy is induced in response to lysosomal damage caused by persistent accumulation of AS fibrils. Importantly, triggering of the autophagic response appears to be an attempt at lysosomal quality control and not for engulfment of fibrillar AS.

+ View Abstract

Journal of cell science, , 1477-9137, , 2018

PMID:30404831

Open Access

Autophagy, Inflammation, and Metabolism (AIM) Center of Biomedical Research Excellence: supporting the next generation of autophagy researchers and fostering international collaborations.
Deretic V, Prossnitz E, Burge M, Campen MJ, Cannon J, Liu KJ, Sklar LA, Allers L, Garcia SA, Baehrecke EH, Behrends C, Cecconi F, Codogno P, Chen GC, Elazar Z, Eskelinen EL, Fourie B, Gozuacik D, Hong W, Hotamisligi G, Jäättelä M, Jo EK, Johansen T, Juhász G, Kimchi A, Ktistakis N, Kroemer G, MIzushima N, Münz C, Reggiori F, Rubinsztein D, Ryan K, Schroder K, Simonsen A, Tooze S, Vaccaro M, Yoshimori T, Yu L, Zhang H, Klionsky DJ

Recently, NIH has funded a center for autophagy research named the Autophagy, Inflammation, and Metabolism (AIM) Center of Biomedical Research Excellence, located at the University of New Mexico Health Science Center (UNM HSC), with aspirations to promote autophagy research locally, nationally, and internationally. The center has 3 major missions: (i) to support junior faculty in their endeavors to develop investigations in this area and obtain independent funding; (ii) to develop and provide technological platforms to advance autophagy research with emphasis on cellular approaches for high quality reproducible research; and (iii) to foster international collaborations through the formation of an International Council of Affiliate Members and through hosting national and international workshops and symposia. Scientifically, the AIM center is focused on autophagy and its intersections with other processes, with emphasis on both fundamental discoveries and applied translational research.

+ View Abstract

Autophagy, , 1554-8635, , 2018

PMID:29938597

In praise of M. Anselmier who first used the term "autophagie" in 1859.
Ktistakis NT

Autophagy, , 1554-8635, , 2017

PMID:28837378

Molecular definitions of autophagy and related processes.
Galluzzi L, Baehrecke EH, Ballabio A, Boya P, Bravo-San Pedro JM, Cecconi F, Choi AM, Chu CT, Codogno P, Colombo MI, Cuervo AM, Debnath J, Deretic V, Dikic I, Eskelinen EL, Fimia GM, Fulda S, Gewirtz DA, Green DR, Hansen M, Harper JW, Jäättelä M, Johansen T, Juhasz G, Kimmelman AC, Kraft C, Ktistakis NT, Kumar S, Levine B, Lopez-Otin C, Madeo F, Martens S, Martinez J, Melendez A, Mizushima N, Münz C, Murphy LO, Penninger JM, Piacentini M, Reggiori F, Rubinsztein DC, Ryan KM, Santambrogio L, Scorrano L, Simon AK, Simon HU, Simonsen A, Tavernarakis N, Tooze SA, Yoshimori T, Yuan J, Yue Z, Zhong Q, Kroemer G

Over the past two decades, the molecular machinery that underlies autophagic responses has been characterized with ever increasing precision in multiple model organisms. Moreover, it has become clear that autophagy and autophagy-related processes have profound implications for human pathophysiology. However, considerable confusion persists about the use of appropriate terms to indicate specific types of autophagy and some components of the autophagy machinery, which may have detrimental effects on the expansion of the field. Driven by the overt recognition of such a potential obstacle, a panel of leading experts in the field attempts here to define several autophagy-related terms based on specific biochemical features. The ultimate objective of this collaborative exchange is to formulate recommendations that facilitate the dissemination of knowledge within and outside the field of autophagy research.

+ View Abstract

The EMBO journal, , 1460-2075, , 2017

PMID:28596378

Phospholipase D activity couples plasma membrane endocytosis with retromer dependent recycling.
Thakur R, Panda A, Coessens E, Raj N, Yadav S, Balakrishnan S, Zhang Q, Georgiev P, Basak B, Pasricha R, Wakelam MJ, Ktistakis NT, Padinjat R

During illumination, the light sensitive plasma membrane (rhabdomere) of Drosophila photoreceptors undergoes turnover with consequent changes in size and composition. However the mechanism by which illumination is coupled to rhabdomere turnover remains unclear. We find that photoreceptors contain a light-dependent phospholipase D (PLD) activity. During illumination, loss of PLD resulted in an enhanced reduction in rhabdomere size, accumulation of Rab7 positive, rhodopsin1-containing vesicles (RLVs) in the cell body and reduced rhodopsin protein. These phenotypes were associated with reduced levels of phosphatidic acid, the product of PLD activity and were rescued by reconstitution with catalytically active PLD. In wild type photoreceptors, during illumination, enhanced PLD activity was sufficient to clear RLVs from the cell body by a process dependent on Arf1-GTP levels and retromer complex function. Thus, during illumination, PLD activity couples endocytosis of RLVs with their recycling to the plasma membrane thus maintaining plasma membrane size and composition.

+ View Abstract

eLife, 5, 2050-084X, , 2016

PMID:27848911

Open Access

Assembly of early machinery for autophagy induction: novel insights from high resolution microscopy.
Ktistakis NT, Walker SA, Karanasios E

Oncotarget, , 1949-2553, , 2016

PMID:27829241

Open Access

Dynamics of mTORC1 activation in response to amino acids.
Manifava M, Smith M, Rotondo S, Walker S, Niewczas I, Zoncu R, Clark J, Ktistakis NT

Amino acids are essential activators of mTORC1 via a complex containing RAG GTPases, RAGULATOR and the vacuolar ATPase. Sensing of amino acids causes translocation of mTORC1 to lysosomes, an obligate step for activation. To examine the spatial and temporal dynamics of this translocation, we used live imaging of the mTORC1 component RAPTOR and a cell permeant fluorescent analogue of di-leucine methyl ester. Translocation to lysosomes is a transient event, occurring within 2 min of aa addition and peaking within 5 min. It is temporally coupled with fluorescent leucine appearance in lysosomes and is sustained in comparison to aa stimulation. Sestrin2 and the vacuolar ATPase are negative and positive regulators of mTORC1 activity in our experimental system. Of note, phosphorylation of canonical mTORC1 targets is delayed compared to lysosomal translocation suggesting a dynamic and transient passage of mTORC1 from the lysosomal surface before targetting its substrates elsewhere.

+ View Abstract

eLife, 5, 2050-084X, , 2016

PMID:27725083

Open Access

Characterization of Atg38 and NRBF2, a fifth subunit of the autophagic Vps34/PIK3C3 complex.
Ohashi Y, Soler N, García Ortegón M, Zhang L, Kirsten ML, Perisic O, Masson GR, Burke JE, Jakobi AJ, Apostolakis AA, Johnson CM, Ohashi M, Ktistakis NT, Sachse C, Williams RL

The phosphatidylinositol 3-kinase Vps34 is part of several protein complexes. The structural organization of heterotetrameric complexes is starting to emerge, but little is known about organization of additional accessory subunits that interact with these assemblies. Combining hydrogen-deuterium exchange mass spectrometry (HDX-MS), X-ray crystallography and electron microscopy (EM), we have characterized Atg38 and its human ortholog NRBF2, accessory components of complex I consisting of Vps15-Vps34-Vps30/Atg6-Atg14 (yeast) and PIK3R4/VPS15-PIK3C3/VPS34-BECN1/Beclin 1-ATG14 (human). HDX-MS shows that Atg38 binds the Vps30-Atg14 subcomplex of complex I, using mainly its N-terminal MIT domain and bridges the coiled-coil I regions of Atg14 and Vps30 in the base of complex I. The Atg38 C-terminal domain is important for localization to the phagophore assembly site (PAS) and homodimerization. Our 2.2 Å resolution crystal structure of the Atg38 C-terminal homodimerization domain shows 2 segments of α-helices assembling into a mushroom-like asymmetric homodimer with a 4-helix cap and a parallel coiled-coil stalk. One Atg38 homodimer engages a single complex I. This is in sharp contrast to human NRBF2, which also forms a homodimer, but this homodimer can bridge 2 complex I assemblies.

+ View Abstract

Autophagy, , 1554-8635, , 2016

PMID:27630019

Autophagy initiation by ULK complex assembly on ER tubulovesicular regions marked by ATG9 vesicles.
Karanasios E, Walker SA, Okkenhaug H, Manifava M, Hummel E, Zimmermann H, Ahmed Q, Domart MC, Collinson L, Ktistakis NT

Autophagosome formation requires sequential translocation of autophagy-specific proteins to membranes enriched in PI3P and connected to the ER. Preceding this, the earliest autophagy-specific structure forming de novo is a small punctum of the ULK1 complex. The provenance of this structure and its mode of formation are unknown. We show that the ULK1 structure emerges from regions, where ATG9 vesicles align with the ER and its formation requires ER exit and coatomer function. Super-resolution microscopy reveals that the ULK1 compartment consists of regularly assembled punctate elements that cluster in progressively larger spherical structures and associates uniquely with the early autophagy machinery. Correlative electron microscopy after live imaging shows tubulovesicular membranes present at the locus of this structure. We propose that the nucleation of autophagosomes occurs in regions, where the ULK1 complex coalesces with ER and the ATG9 compartment.

+ View Abstract

Nature communications, 7, 2041-1723, , 2016

PMID:27510922

Open Access

Digesting the Expanding Mechanisms of Autophagy.
Ktistakis NT, Tooze SA

Autophagy is a catabolic 'self-eating' pathway that is emerging as a crucial integration point in cell physiology. With its own set of genes, the autophagy pathway communicates with virtually all signalling networks and organelles. Recent advances have been made in understanding the origin of the autophagosomal membrane, novel regulators, and the mechanisms by which specific intracellular membranes become autophagy substrates. New studies on noncanonical autophagy, mediated by subsets of autophagy proteins, and the role of autophagy proteins in non-autophagy pathways are also emerging in many different biological contexts. Our understanding of canonical autophagy, including membrane origin and autophagy proteins, needs to be considered together with emerging noncanonical pathways.

+ View Abstract

Trends in cell biology, , 1879-3088, , 2016

PMID:27050762

Guidelines for the use and interpretation of assays for monitoring autophagy (3rd edition).
Klionsky DJ, Abdelmohsen K, Abe A, Abedin MJ, Abeliovich H, Acevedo Arozena A, Adachi H, Adams CM, Adams PD, Adeli K, Adhihetty PJ, Adler SG, Agam G, Agarwal R, Aghi MK, Agnello M, Agostinis P, Aguilar PV, Aguirre-Ghiso J, Airoldi EM, Ait-Si-Ali S, Akematsu T, Akporiaye ET, Al-Rubeai M, Albaiceta GM, Albanese C, Albani D, Albert ML, Aldudo J, Algül H, Alirezaei M, Alloza I, Almasan A, Almonte-Beceril M, Alnemri ES, Alonso C, Altan-Bonnet N, Altieri DC, Alvarez S, Alvarez-Erviti L, Alves S, Amadoro G, Amano A, Amantini C, Ambrosio S, Amelio I, Amer AO, Amessou M, Amon A, An Z, Anania FA, Andersen SU, Andley UP, Andreadi CK, Andrieu-Abadie N, Anel A, Ann DK, Anoopkumar-Dukie S, Antonioli M, Aoki H, Apostolova N, Aquila S, Aquilano K, Araki K, Arama E, Aranda A, Araya J, Arcaro A, Arias E, Arimoto H, Ariosa AR, Armstrong JL, Arnould T, Arsov I, Asanuma K, Askanas V, Asselin E, Atarashi R, Atherton SS, Atkin JD, Attardi LD, Auberger P, Auburger G, Aurelian L, Autelli R, Avagliano L, Avantaggiati ML, Avrahami L, Awale S, Azad N, Bachetti T, Backer JM, Bae DH, Bae JS, Bae ON, Bae SH, Baehrecke EH, Baek SH, Baghdiguian S, Bagniewska-Zadworna A, Bai H, Bai J, Bai XY, Bailly Y, Balaji KN, Balduini W, Ballabio A, Balzan R, Banerjee R, Bánhegyi G, Bao H, Barbeau B, Barrachina MD, Barreiro E, Bartel B, Bartolomé A, Bassham DC, Bassi MT, Bast RC, Basu A, Batista MT, Batoko H, Battino M, Bauckman K, Baumgarner BL, Bayer KU, Beale R, Beaulieu JF, Beck GR, Becker C, Beckham JD, Bédard PA, Bednarski PJ, Begley TJ, Behl C, Behrends C, Behrens GM, Behrns KE, Bejarano E, Belaid A, Belleudi F, Bénard G, Berchem G, Bergamaschi D, Bergami M, Berkhout B, Berliocchi L, Bernard A, Bernard M, Bernassola F, Bertolotti A, Bess AS, Besteiro S, Bettuzzi S, Bhalla S, Bhattacharyya S, Bhutia SK, Biagosch C, Bianchi MW, Biard-Piechaczyk M, Billes V, Bincoletto C, Bingol B, Bird SW, Bitoun M, Bjedov I, Blackstone C, Blanc L, Blanco GA, Blomhoff HK, Boada-Romero E, Böckler S, Boes M, Boesze-Battaglia K, Boise LH, Bolino A, Boman A, Bonaldo P, Bordi M, Bosch J, Botana LM, Botti J, Bou G, Bouché M, Bouchecareilh M, Boucher MJ, Boulton ME, Bouret SG, Boya P, Boyer-Guittaut M, Bozhkov PV, Brady N, Braga VM, Brancolini C, Braus GH, Bravo-San Pedro JM, Brennan LA, Bresnick EH, Brest P, Bridges D, Bringer MA, Brini M, Brito GC, Brodin B, Brookes PS, Brown EJ, Brown K, Broxmeyer HE, Bruhat A, Brum PC, Brumell JH, Brunetti-Pierri N, Bryson-Richardson RJ, Buch S, Buchan AM, Budak H, Bulavin DV, Bultman SJ, Bultynck G, Bumbasirevic V, Burelle Y, Burke RE, Burmeister M, Bütikofer P, Caberlotto L, Cadwell K, Cahova M, Cai D, Cai J, Cai Q, Calatayud S, Camougrand N, Campanella M, Campbell GR, Campbell M, Campello S, Candau R, Caniggia I, Cantoni L, Cao L, Caplan AB, Caraglia M, Cardinali C, Cardoso SM, Carew JS, Carleton LA, Carlin CR, Carloni S, Carlsson SR, Carmona-Gutierrez D, Carneiro LA, Carnevali O, Carra S, Carrier A, Carroll B, Casas C, Casas J, Cassinelli G, Castets P, Castro-Obregon S, Cavallini G, Ceccherini I, Cecconi F, Cederbaum AI, Ceña V, Cenci S, Cerella C, Cervia D, Cetrullo S, Chaachouay H, Chae HJ, Chagin AS, Chai CY, Chakrabarti G, Chamilos G, Chan EY, Chan MT, Chandra D, Chandra P, Chang CP, Chang RC, Chang TY, Chatham JC, Chatterjee S, Chauhan S, Che Y, Cheetham ME, Cheluvappa R, Chen CJ, Chen G, Chen GC, Chen G, Chen H, Chen JW, Chen JK, Chen M, Chen M, Chen P, Chen Q, Chen Q, Chen SD, Chen S, Chen SS, Chen W, Chen WJ, Chen WQ, Chen W, Chen X, Chen YH, Chen YG, Chen Y, Chen Y, Chen Y, Chen YJ, Chen YQ, Chen Y, Chen Z, Chen Z, Cheng A, Cheng CH, Cheng H, Cheong H, Cherry S, Chesney J, Cheung CH, Chevet E, Chi HC, Chi SG, Chiacchiera F, Chiang HL, Chiarelli R, Chiariello M, Chieppa M, Chin LS, Chiong M, Chiu GN, Cho DH, Cho SG, Cho WC, Cho YY, Cho YS, Choi AM, Choi EJ, Choi EK, Choi J, Choi ME, Choi SI, Chou TF, Chouaib S, Choubey D, Choubey V, Chow KC, Chowdhury K, Chu CT, Chuang TH, Chun T, Chung H, Chung T, Chung YL, Chwae YJ, Cianfanelli V, Ciarcia R, Ciechomska IA, Ciriolo MR, Cirone M, Claerhout S, Clague MJ, Clària J, Clarke PG, Clarke R, Clementi E, Cleyrat C, Cnop M, Coccia EM, Cocco T, Codogno P, Coers J, Cohen EE, Colecchia D, Coletto L, Coll NS, Colucci-Guyon E, Comincini S, Condello M, Cook KL, Coombs GH, Cooper CD, Cooper JM, Coppens I, Corasaniti MT, Corazzari M, Corbalan R, Corcelle-Termeau E, Cordero MD, Corral-Ramos C, Corti O, Cossarizza A, Costelli P, Costes S, Cotman SL, Coto-Montes A, Cottet S, Couve E, Covey LR, Cowart LA, Cox JS, Coxon FP, Coyne CB, Cragg MS, Craven RJ, Crepaldi T, Crespo JL, Criollo A, Crippa V, Cruz MT, Cuervo AM, Cuezva JM, Cui T, Cutillas PR, Czaja MJ, Czyzyk-Krzeska MF, Dagda RK, Dahmen U, Dai C, Dai W, Dai Y, Dalby KN, Dalla Valle L, Dalmasso G, D'Amelio M, Damme M, Darfeuille-Michaud A, Dargemont C, Darley-Usmar VM, Dasarathy S, Dasgupta B, Dash S, Dass CR, Davey HM, Davids LM, Dávila D, Davis RJ, Dawson TM, Dawson VL, Daza P, de Belleroche J, de Figueiredo P, de Figueiredo RC, de la Fuente J, De Martino L, De Matteis A, De Meyer GR, De Milito A, De Santi M, de Souza W, De Tata V, De Zio D, Debnath J, Dechant R, Decuypere JP, Deegan S, Dehay B, Del Bello B, Del Re DP, Delage-Mourroux R, Delbridge LM, Deldicque L, Delorme-Axford E, Deng Y, Dengjel J, Denizot M, Dent P, Der CJ, Deretic V, Derrien B, Deutsch E, Devarenne TP, Devenish RJ, Di Bartolomeo S, Di Daniele N, Di Domenico F, Di Nardo A, Di Paola S, Di Pietro A, Di Renzo L, DiAntonio A, Díaz-Araya G, Díaz-Laviada I, Diaz-Meco MT, Diaz-Nido J, Dickey CA, Dickson RC, Diederich M, Digard P, Dikic I, Dinesh-Kumar SP, Ding C, Ding WX, Ding Z, Dini L, Distler JH, Diwan A, Djavaheri-Mergny M, Dmytruk K, Dobson RC, Doetsch V, Dokladny K, Dokudovskaya S, Donadelli M, Dong XC, Dong X, Dong Z, Donohue TM, Doran KS, D'Orazi G, Dorn GW, Dosenko V, Dridi S, Drucker L, Du J, Du LL, Du L, du Toit A, Dua P, Duan L, Duann P, Dubey VK, Duchen MR, Duchosal MA, Duez H, Dugail I, Dumit VI, Duncan MC, Dunlop EA, Dunn WA, Dupont N, Dupuis L, Durán RV, Durcan TM, Duvezin-Caubet S, Duvvuri U, Eapen V, Ebrahimi-Fakhari D, Echard A, Eckhart L, Edelstein CL, Edinger AL, Eichinger L, Eisenberg T, Eisenberg-Lerner A, Eissa NT, El-Deiry WS, El-Khoury V, Elazar Z, Eldar-Finkelman H, Elliott CJ, Emanuele E, Emmenegger U, Engedal N, Engelbrecht AM, Engelender S, Enserink JM, Erdmann R, Erenpreisa J, Eri R, Eriksen JL, Erman A, Escalante R, Eskelinen EL, Espert L, Esteban-Martínez L, Evans TJ, Fabri M, Fabrias G, Fabrizi C, Facchiano A, Færgeman NJ, Faggioni A, Fairlie WD, Fan C, Fan D, Fan J, Fang S, Fanto M, Fanzani A, Farkas T, Faure M, Favier FB, Fearnhead H, Federici M, Fei E, Felizardo TC, Feng H, Feng Y, Feng Y, Ferguson TA, Fernández ÁF, Fernandez-Barrena MG, Fernandez-Checa JC, Fernández-López A, Fernandez-Zapico ME, Feron O, Ferraro E, Ferreira-Halder CV, Fesus L, Feuer R, Fiesel FC, Filippi-Chiela EC, Filomeni G, Fimia GM, Fingert JH, Finkbeiner S, Finkel T, Fiorito F, Fisher PB, Flajolet M, Flamigni F, Florey O, Florio S, Floto RA, Folini M, Follo C, Fon EA, Fornai F, Fortunato F, Fraldi A, Franco R, Francois A, François A, Frankel LB, Fraser ID, Frey N, Freyssenet DG, Frezza C, Friedman SL, Frigo DE, Fu D, Fuentes JM, Fueyo J, Fujitani Y, Fujiwara Y, Fujiya M, Fukuda M, Fulda S, Fusco C, Gabryel B, Gaestel M, Gailly P, Gajewska M, Galadari S, Galili G, Galindo I, Galindo MF, Galliciotti G, Galluzzi L, Galluzzi L, Galy V, Gammoh N, Gandy S, Ganesan AK, Ganesan S, Ganley IG, Gannagé M, Gao FB, Gao F, Gao JX, García Nannig L, García Véscovi E, Garcia-Macía M, Garcia-Ruiz C, Garg AD, Garg PK, Gargini R, Gassen NC, Gatica D, Gatti E, Gavard J, Gavathiotis E, Ge L, Ge P, Ge S, Gean PW, Gelmetti V, Genazzani AA, Geng J, Genschik P, Gerner L, Gestwicki JE, Gewirtz DA, Ghavami S, Ghigo E, Ghosh D, Giammarioli AM, Giampieri F, Giampietri C, Giatromanolaki A, Gibbings DJ, Gibellini L, Gibson SB, Ginet V, Giordano A, Giorgini F, Giovannetti E, Girardin SE, Gispert S, Giuliano S, Gladson CL, Glavic A, Gleave M, Godefroy N, Gogal RM, Gokulan K, Goldman GH, Goletti D, Goligorsky MS, Gomes AV, Gomes LC, Gomez H, Gomez-Manzano C, Gómez-Sánchez R, Gonçalves DA, Goncu E, Gong Q, Gongora C, Gonzalez CB, Gonzalez-Alegre P, Gonzalez-Cabo P, González-Polo RA, Goping IS, Gorbea C, Gorbunov NV, Goring DR, Gorman AM, Gorski SM, Goruppi S, Goto-Yamada S, Gotor C, Gottlieb RA, Gozes I, Gozuacik D, Graba Y, Graef M, Granato GE, Grant GD, Grant S, Gravina GL, Green DR, Greenhough A, Greenwood MT, Grimaldi B, Gros F, Grose C, Groulx JF, Gruber F, Grumati P, Grune T, Guan JL, Guan KL, Guerra B, Guillen C, Gulshan K, Gunst J, Guo C, Guo L, Guo M, Guo W, Guo XG, Gust AA, Gustafsson ÅB, Gutierrez E, Gutierrez MG, Gwak HS, Haas A, Haber JE, Hadano S, Hagedorn M, Hahn DR, Halayko AJ, Hamacher-Brady A, Hamada K, Hamai A, Hamann A, Hamasaki M, Hamer I, Hamid Q, Hammond EM, Han F, Han W, Handa JT, Hanover JA, Hansen M, Harada M, Harhaji-Trajkovic L, Harper JW, Harrath AH, Harris AL, Harris J, Hasler U, Hasselblatt P, Hasui K, Hawley RG, Hawley TS, He C, He CY, He F, He G, He RR, He XH, He YW, He YY, Heath JK, Hébert MJ, Heinzen RA, Helgason GV, Hensel M, Henske EP, Her C, Herman PK, Hernández A, Hernandez C, Hernández-Tiedra S, Hetz C, Hiesinger PR, Higaki K, Hilfiker S, Hill BG, Hill JA, Hill WD, Hino K, Hofius D, Hofman P, Höglinger GU, Höhfeld J, Holz MK, Hong Y, Hood DA, Hoozemans JJ, Hoppe T, Hsu C, Hsu CY, Hsu LC, Hu D, Hu G, Hu HM, Hu H, Hu MC, Hu YC, Hu ZW, Hua F, Hua Y, Huang C, Huang HL, Huang KH, Huang KY, Huang S, Huang S, Huang WP, Huang YR, Huang Y, Huang Y, Huber TB, Huebbe P, Huh WK, Hulmi JJ, Hur GM, Hurley JH, Husak Z, Hussain SN, Hussain S, Hwang JJ, Hwang S, Hwang TI, Ichihara A, Imai Y, Imbriano C, Inomata M, Into T, Iovane V, Iovanna JL, Iozzo RV, Ip NY, Irazoqui JE, Iribarren P, Isaka Y, Isakovic AJ, Ischiropoulos H, Isenberg JS, Ishaq M, Ishida H, Ishii I, Ishmael JE, Isidoro C, Isobe KI, Isono E, Issazadeh-Navikas S, Itahana K, Itakura E, Ivanov AI, Iyer AK, Izquierdo JM, Izumi Y, Izzo V, Jäättelä M, Jaber N, Jackson DJ, Jackson WT, Jacob TG, Jacques TS, Jagannath C, Jain A, Jana NR, Jang BK, Jani A, Janji B, Jannig PR, Jansson PJ, Jean S, Jendrach M, Jeon JH, Jessen N, Jeung EB, Jia K, Jia L, Jiang H, Jiang H, Jiang L, Jiang T, Jiang X, Jiang X, Jiang X, Jiang Y, Jiang Y, Jiménez A, Jin C, Jin H, Jin L, Jin M, Jin S, Jinwal UK, Jo EK, Johansen T, Johnson DE, Johnson GV, Johnson JD, Jonasch E, Jones C, Joosten LA, Jordan J, Joseph AM, Joseph B, Joubert AM, Ju D, Ju J, Juan HF, Juenemann K, Juhász G, Jung HS, Jung JU, Jung YK, Jungbluth H, Justice MJ, Jutten B, Kaakoush NO, Kaarniranta K, Kaasik A, Kabuta T, Kaeffer B, Kågedal K, Kahana A, Kajimura S, Kakhlon O, Kalia M, Kalvakolanu DV, Kamada Y, Kambas K, Kaminskyy VO, Kampinga HH, Kandouz M, Kang C, Kang R, Kang TC, Kanki T, Kanneganti TD, Kanno H, Kanthasamy AG, Kantorow M, Kaparakis-Liaskos M, Kapuy O, Karantza V, Karim MR, Karmakar P, Kaser A, Kaushik S, Kawula T, Kaynar AM, Ke PY, Ke ZJ, Kehrl JH, Keller KE, Kemper JK, Kenworthy AK, Kepp O, Kern A, Kesari S, Kessel D, Ketteler R, Kettelhut ID, Khambu B, Khan MM, Khandelwal VK, Khare S, Kiang JG, Kiger AA, Kihara A, Kim AL, Kim CH, Kim DR, Kim DH, Kim EK, Kim HY, Kim HR, Kim JS, Kim JH, Kim JC, Kim JH, Kim KW, Kim MD, Kim MM, Kim PK, Kim SW, Kim SY, Kim YS, Kim Y, Kimchi A, Kimmelman AC, Kimura T, King JS, Kirkegaard K, Kirkin V, Kirshenbaum LA, Kishi S, Kitajima Y, Kitamoto K, Kitaoka Y, Kitazato K, Kley RA, Klimecki WT, Klinkenberg M, Klucken J, Knævelsrud H, Knecht E, Knuppertz L, Ko JL, Kobayashi S, Koch JC, Koechlin-Ramonatxo C, Koenig U, Koh YH, Köhler K, Kohlwein SD, Koike M, Komatsu M, Kominami E, Kong D, Kong HJ, Konstantakou EG, Kopp BT, Korcsmaros T, Korhonen L, Korolchuk VI, Koshkina NV, Kou Y, Koukourakis MI, Koumenis C, Kovács AL, Kovács T, Kovacs WJ, Koya D, Kraft C, Krainc D, Kramer H, Kravic-Stevovic T, Krek W, Kretz-Remy C, Krick R, Krishnamurthy M, Kriston-Vizi J, Kroemer G, Kruer MC, Kruger R, Ktistakis NT, Kuchitsu K, Kuhn C, Kumar AP, Kumar A, Kumar A, Kumar D, Kumar D, Kumar R, Kumar S, Kundu M, Kung HJ, Kuno A, Kuo SH, Kuret J, Kurz T, Kwok T, Kwon TK, Kwon YT, Kyrmizi I, La Spada AR, Lafont F, Lahm T, Lakkaraju A, Lam T, Lamark T, Lancel S, Landowski TH, Lane DJ, Lane JD, Lanzi C, Lapaquette P, Lapierre LR, Laporte J, Laukkarinen J, Laurie GW, Lavandero S, Lavie L, LaVoie MJ, Law BY, Law HK, Law KB, Layfield R, Lazo PA, Le Cam L, Le Roch KG, Le Stunff H, Leardkamolkarn V, Lecuit M, Lee BH, Lee CH, Lee EF, Lee GM, Lee HJ, Lee H, Lee JK, Lee J, Lee JH, Lee JH, Lee M, Lee MS, Lee PJ, Lee SW, Lee SJ, Lee SJ, Lee SY, Lee SH, Lee SS, Lee SJ, Lee S, Lee YR, Lee YJ, Lee YH, Leeuwenburgh C, Lefort S, Legouis R, Lei J, Lei QY, Leib DA, Leibowitz G, Lekli I, Lemaire SD, Lemasters JJ, Lemberg MK, Lemoine A, Leng S, Lenz G, Lenzi P, Lerman LO, Lettieri Barbato D, Leu JI, Leung HY, Levine B, Lewis PA, Lezoualc'h F, Li C, Li F, Li FJ, Li J, Li K, Li L, Li M, Li M, Li Q, Li R, Li S, Li W, Li W, Li X, Li Y, Lian J, Liang C, Liang Q, Liao Y, Liberal J, Liberski PP, Lie P, Lieberman AP, Lim HJ, Lim KL, Lim K, Lima RT, Lin CS, Lin CF, Lin F, Lin F, Lin FC, Lin K, Lin KH, Lin PH, Lin T, Lin WW, Lin YS, Lin Y, Linden R, Lindholm D, Lindqvist LM, Lingor P, Linkermann A, Liotta LA, Lipinski MM, Lira VA, Lisanti MP, Liton PB, Liu B, Liu C, Liu CF, Liu F, Liu HJ, Liu J, Liu JJ, Liu JL, Liu K, Liu L, Liu L, Liu Q, Liu RY, Liu S, Liu S, Liu W, Liu XD, Liu X, Liu XH, Liu X, Liu X, Liu X, Liu Y, Liu Y, Liu Z, Liu Z, Liuzzi JP, Lizard G, Ljujic M, Lodhi IJ, Logue SE, Lokeshwar BL, Long YC, Lonial S, Loos B, López-Otín C, López-Vicario C, Lorente M, Lorenzi PL, Lõrincz P, Los M, Lotze MT, Lovat PE, Lu B, Lu B, Lu J, Lu Q, Lu SM, Lu S, Lu Y, Luciano F, Luckhart S, Lucocq JM, Ludovico P, Lugea A, Lukacs NW, Lum JJ, Lund AH, Luo H, Luo J, Luo S, Luparello C, Lyons T, Ma J, Ma Y, Ma Y, Ma Z, Machado J, Machado-Santelli GM, Macian F, MacIntosh GC, MacKeigan JP, Macleod KF, MacMicking JD, MacMillan-Crow LA, Madeo F, Madesh M, Madrigal-Matute J, Maeda A, Maeda T, Maegawa G, Maellaro E, Maes H, Magariños M, Maiese K, Maiti TK, Maiuri L, Maiuri MC, Maki CG, Malli R, Malorni W, Maloyan A, Mami-Chouaib F, Man N, Mancias JD, Mandelkow EM, Mandell MA, Manfredi AA, Manié SN, Manzoni C, Mao K, Mao Z, Mao ZW, Marambaud P, Marconi AM, Marelja Z, Marfe G, Margeta M, Margittai E, Mari M, Mariani FV, Marin C, Marinelli S, Mariño G, Markovic I, Marquez R, Martelli AM, Martens S, Martin KR, Martin SJ, Martin S, Martin-Acebes MA, Martín-Sanz P, Martinand-Mari C, Martinet W, Martinez J, Martinez-Lopez N, Martinez-Outschoorn U, Martínez-Velázquez M, Martinez-Vicente M, Martins WK, Mashima H, Mastrianni JA, Matarese G, Matarrese P, Mateo R, Matoba S, Matsumoto N, Matsushita T, Matsuura A, Matsuzawa T, Mattson MP, Matus S, Maugeri N, Mauvezin C, Mayer A, Maysinger D, Mazzolini GD, McBrayer MK, McCall K, McCormick C, McInerney GM, McIver SC, McKenna S, McMahon JJ, McNeish IA, Mechta-Grigoriou F, Medema JP, Medina DL, Megyeri K, Mehrpour M, Mehta JL, Mei Y, Meier UC, Meijer AJ, Meléndez A, Melino G, Melino S, de Melo EJ, Mena MA, Meneghini MD, Menendez JA, Menezes R, Meng L, Meng LH, Meng S, Menghini R, Menko AS, Menna-Barreto RF, Menon MB, Meraz-Ríos MA, Merla G, Merlini L, Merlot AM, Meryk A, Meschini S, Meyer JN, Mi MT, Miao CY, Micale L, Michaeli S, Michiels C, Migliaccio AR, Mihailidou AS, Mijaljica D, Mikoshiba K, Milan E, Miller-Fleming L, Mills GB, Mills IG, Minakaki G, Minassian BA, Ming XF, Minibayeva F, Minina EA, Mintern JD, Minucci S, Miranda-Vizuete A, Mitchell CH, Miyamoto S, Miyazawa K, Mizushima N, Mnich K, Mograbi B, Mohseni S, Moita LF, Molinari M, Molinari M, Møller AB, Mollereau B, Mollinedo F, Mongillo M, Monick MM, Montagnaro S, Montell C, Moore DJ, Moore MN, Mora-Rodriguez R, Moreira PI, Morel E, Morelli MB, Moreno S, Morgan MJ, Moris A, Moriyasu Y, Morrison JL, Morrison LA, Morselli E, Moscat J, Moseley PL, Mostowy S, Motori E, Mottet D, Mottram JC, Moussa CE, Mpakou VE, Mukhtar H, Mulcahy Levy JM, Muller S, Muñoz-Moreno R, Muñoz-Pinedo C, Münz C, Murphy ME, Murray JT, Murthy A, Mysorekar IU, Nabi IR, Nabissi M, Nader GA, Nagahara Y, Nagai Y, Nagata K, Nagelkerke A, Nagy P, Naidu SR, Nair S, Nakano H, Nakatogawa H, Nanjundan M, Napolitano G, Naqvi NI, Nardacci R, Narendra DP, Narita M, Nascimbeni AC, Natarajan R, Navegantes LC, Nawrocki ST, Nazarko TY, Nazarko VY, Neill T, Neri LM, Netea MG, Netea-Maier RT, Neves BM, Ney PA, Nezis IP, Nguyen HT, Nguyen HP, Nicot AS, Nilsen H, Nilsson P, Nishimura M, Nishino I, Niso-Santano M, Niu H, Nixon RA, Njar VC, Noda T, Noegel AA, Nolte EM, Norberg E, Norga KK, Noureini SK, Notomi S, Notterpek L, Nowikovsky K, Nukina N, Nürnberger T, O'Donnell VB, O'Donovan T, O'Dwyer PJ, Oehme I, Oeste CL, Ogawa M, Ogretmen B, Ogura Y, Oh YJ, Ohmuraya M, Ohshima T, Ojha R, Okamoto K, Okazaki T, Oliver FJ, Ollinger K, Olsson S, Orban DP, Ordonez P, Orhon I, Orosz L, O'Rourke EJ, Orozco H, Ortega AL, Ortona E, Osellame LD, Oshima J, Oshima S, Osiewacz HD, Otomo T, Otsu K, Ou JJ, Outeiro TF, Ouyang DY, Ouyang H, Overholtzer M, Ozbun MA, Ozdinler PH, Ozpolat B, Pacelli C, Paganetti P, Page G, Pages G, Pagnini U, Pajak B, Pak SC, Pakos-Zebrucka K, Pakpour N, Palková Z, Palladino F, Pallauf K, Pallet N, Palmieri M, Paludan SR, Palumbo C, Palumbo S, Pampliega O, Pan H, Pan W, Panaretakis T, Pandey A, Pantazopoulou A, Papackova Z, Papademetrio DL, Papassideri I, Papini A, Parajuli N, Pardo J, Parekh VV, Parenti G, Park JI, Park J, Park OK, Parker R, Parlato R, Parys JB, Parzych KR, Pasquet JM, Pasquier B, Pasumarthi KB, Patschan D, Patterson C, Pattingre S, Pattison S, Pause A, Pavenstädt H, Pavone F, Pedrozo Z, Peña FJ, Peñalva MA, Pende M, Peng J, Penna F, Penninger JM, Pensalfini A, Pepe S, Pereira GJ, Pereira PC, Pérez-de la Cruz V, Pérez-Pérez ME, Pérez-Rodríguez D, Pérez-Sala D, Perier C, Perl A, Perlmutter DH, Perrotta I, Pervaiz S, Pesonen M, Pessin JE, Peters GJ, Petersen M, Petrache I, Petrof BJ, Petrovski G, Phang JM, Piacentini M, Pierdominici M, Pierre P, Pierrefite-Carle V, Pietrocola F, Pimentel-Muiños FX, Pinar M, Pineda B, Pinkas-Kramarski R, Pinti M, Pinton P, Piperdi B, Piret JM, Platanias LC, Platta HW, Plowey ED, Pöggeler S, Poirot M, Polčic P, Poletti A, Poon AH, Popelka H, Popova B, Poprawa I, Poulose SM, Poulton J, Powers SK, Powers T, Pozuelo-Rubio M, Prak K, Prange R, Prescott M, Priault M, Prince S, Proia RL, Proikas-Cezanne T, Prokisch H, Promponas VJ, Przyklenk K, Puertollano R, Pugazhenthi S, Puglielli L, Pujol A, Puyal J, Pyeon D, Qi X, Qian WB, Qin ZH, Qiu Y, Qu Z, Quadrilatero J, Quinn F, Raben N, Rabinowich H, Radogna F, Ragusa MJ, Rahmani M, Raina K, Ramanadham S, Ramesh R, Rami A, Randall-Demllo S, Randow F, Rao H, Rao VA, Rasmussen BB, Rasse TM, Ratovitski EA, Rautou PE, Ray SK, Razani B, Reed BH, Reggiori F, Rehm M, Reichert AS, Rein T, Reiner DJ, Reits E, Ren J, Ren X, Renna M, Reusch JE, Revuelta JL, Reyes L, Rezaie AR, Richards RI, Richardson DR, Richetta C, Riehle MA, Rihn BH, Rikihisa Y, Riley BE, Rimbach G, Rippo MR, Ritis K, Rizzi F, Rizzo E, Roach PJ, Robbins J, Roberge M, Roca G, Roccheri MC, Rocha S, Rodrigues CM, Rodríguez CI, de Cordoba SR, Rodriguez-Muela N, Roelofs J, Rogov VV, Rohn TT, Rohrer B, Romanelli D, Romani L, Romano PS, Roncero MI, Rosa JL, Rosello A, Rosen KV, Rosenstiel P, Rost-Roszkowska M, Roth KA, Roué G, Rouis M, Rouschop KM, Ruan DT, Ruano D, Rubinsztein DC, Rucker EB, Rudich A, Rudolf E, Rudolf R, Ruegg MA, Ruiz-Roldan C, Ruparelia AA, Rusmini P, Russ DW, Russo GL, Russo G, Russo R, Rusten TE, Ryabovol V, Ryan KM, Ryter SW, Sabatini DM, Sacher M, Sachse C, Sack MN, Sadoshima J, Saftig P, Sagi-Eisenberg R, Sahni S, Saikumar P, Saito T, Saitoh T, Sakakura K, Sakoh-Nakatogawa M, Sakuraba Y, Salazar-Roa M, Salomoni P, Saluja AK, Salvaterra PM, Salvioli R, Samali A, Sanchez AM, Sánchez-Alcázar JA, Sanchez-Prieto R, Sandri M, Sanjuan MA, Santaguida S, Santambrogio L, Santoni G, Dos Santos CN, Saran S, Sardiello M, Sargent G, Sarkar P, Sarkar S, Sarrias MR, Sarwal MM, Sasakawa C, Sasaki M, Sass M, Sato K, Sato M, Satriano J, Savaraj N, Saveljeva S, Schaefer L, Schaible UE, Scharl M, Schatzl HM, Schekman R, Scheper W, Schiavi A, Schipper HM, Schmeisser H, Schmidt J, Schmitz I, Schneider BE, Schneider EM, Schneider JL, Schon EA, Schönenberger MJ, Schönthal AH, Schorderet DF, Schröder B, Schuck S, Schulze RJ, Schwarten M, Schwarz TL, Sciarretta S, Scotto K, Scovassi AI, Screaton RA, Screen M, Seca H, Sedej S, Segatori L, Segev N, Seglen PO, Seguí-Simarro JM, Segura-Aguilar J, Seki E, Sell C, Selliez I, Semenkovich CF, Semenza GL, Sen U, Serra AL, Serrano-Puebla A, Sesaki H, Setoguchi T, Settembre C, Shacka JJ, Shajahan-Haq AN, Shapiro IM, Sharma S, She H, Shen CJ, Shen CC, Shen HM, Shen S, Shen W, Sheng R, Sheng X, Sheng ZH, Shepherd TG, Shi J, Shi Q, Shi Q, Shi Y, Shibutani S, Shibuya K, Shidoji Y, Shieh JJ, Shih CM, Shimada Y, Shimizu S, Shin DW, Shinohara ML, Shintani M, Shintani T, Shioi T, Shirabe K, Shiri-Sverdlov R, Shirihai O, Shore GC, Shu CW, Shukla D, Sibirny AA, Sica V, Sigurdson CJ, Sigurdsson EM, Sijwali PS, Sikorska B, Silveira WA, Silvente-Poirot S, Silverman GA, Simak J, Simmet T, Simon AK, Simon HU, Simone C, Simons M, Simonsen A, Singh R, Singh SV, Singh SK, Sinha D, Sinha S, Sinicrope FA, Sirko A, Sirohi K, Sishi BJ, Sittler A, Siu PM, Sivridis E, Skwarska A, Slack R, Slaninová I, Slavov N, Smaili SS, Smalley KS, Smith DR, Soenen SJ, Soleimanpour SA, Solhaug A, Somasundaram K, Son JH, Sonawane A, Song C, Song F, Song HK, Song JX, Song W, Soo KY, Sood AK, Soong TW, Soontornniyomkij V, Sorice M, Sotgia F, Soto-Pantoja DR, Sotthibundhu A, Sousa MJ, Spaink HP, Span PN, Spang A, Sparks JD, Speck PG, Spector SA, Spies CD, Springer W, Clair DS, Stacchiotti A, Staels B, Stang MT, Starczynowski DT, Starokadomskyy P, Steegborn C, Steele JW, Stefanis L, Steffan J, Stellrecht CM, Stenmark H, Stepkowski TM, Stern ST, Stevens C, Stockwell BR, Stoka V, Storchova Z, Stork B, Stratoulias V, Stravopodis DJ, Strnad P, Strohecker AM, Ström AL, Stromhaug P, Stulik J, Su YX, Su Z, Subauste CS, Subramaniam S, Sue CM, Suh SW, Sui X, Sukseree S, Sulzer D, Sun FL, Sun J, Sun J, Sun SY, Sun Y, Sun Y, Sun Y, Sundaramoorthy V, Sung J, Suzuki H, Suzuki K, Suzuki N, Suzuki T, Suzuki YJ, Swanson MS, Swanton C, Swärd K, Swarup G, Sweeney ST, Sylvester PW, Szatmari Z, Szegezdi E, Szlosarek PW, Taegtmeyer H, Tafani M, Taillebourg E, Tait SW, Takacs-Vellai K, Takahashi Y, Takáts S, Takemura G, Takigawa N, Talbot NJ, Tamagno E, Tamburini J, Tan CP, Tan L, Tan ML, Tan M, Tan YJ, Tanaka K, Tanaka M, Tang D, Tang D, Tang G, Tanida I, Tanji K, Tannous BA, Tapia JA, Tasset-Cuevas I, Tatar M, Tavassoly I, Tavernarakis N, Taylor A, Taylor GS, Taylor GA, Taylor JP, Taylor MJ, Tchetina EV, Tee AR, Teixeira-Clerc F, Telang S, Tencomnao T, Teng BB, Teng RJ, Terro F, Tettamanti G, Theiss AL, Theron AE, Thomas KJ, Thomé MP, Thomes PG, Thorburn A, Thorner J, Thum T, Thumm M, Thurston TL, Tian L, Till A, Ting JP, Titorenko VI, Toker L, Toldo S, Tooze SA, Topisirovic I, Torgersen ML, Torosantucci L, Torriglia A, Torrisi MR, Tournier C, Towns R, Trajkovic V, Travassos LH, Triola G, Tripathi DN, Trisciuoglio D, Troncoso R, Trougakos IP, Truttmann AC, Tsai KJ, Tschan MP, Tseng YH, Tsukuba T, Tsung A, Tsvetkov AS, Tu S, Tuan HY, Tucci M, Tumbarello DA, Turk B, Turk V, Turner RF, Tveita AA, Tyagi SC, Ubukata M, Uchiyama Y, Udelnow A, Ueno T, Umekawa M, Umemiya-Shirafuji R, Underwood BR, Ungermann C, Ureshino RP, Ushioda R, Uversky VN, Uzcátegui NL, Vaccari T, Vaccaro MI, Váchová L, Vakifahmetoglu-Norberg H, Valdor R, Valente EM, Vallette F, Valverde AM, Van den Berghe G, Van Den Bosch L, van den Brink GR, van der Goot FG, van der Klei IJ, van der Laan LJ, van Doorn WG, van Egmond M, van Golen KL, Van Kaer L, van Lookeren Campagne M, Vandenabeele P, Vandenberghe W, Vanhorebeek I, Varela-Nieto I, Vasconcelos MH, Vasko R, Vavvas DG, Vega-Naredo I, Velasco G, Velentzas AD, Velentzas PD, Vellai T, Vellenga E, Vendelbo MH, Venkatachalam K, Ventura N, Ventura S, Veras PS, Verdier M, Vertessy BG, Viale A, Vidal M, Vieira H, Vierstra RD, Vigneswaran N, Vij N, Vila M, Villar M, Villar VH, Villarroya J, Vindis C, Viola G, Viscomi MT, Vitale G, Vogl DT, Voitsekhovskaja OV, von Haefen C, von Schwarzenberg K, Voth DE, Vouret-Craviari V, Vuori K, Vyas JM, Waeber C, Walker CL, Walker MJ, Walter J, Wan L, Wan X, Wang B, Wang C, Wang CY, Wang C, Wang C, Wang C, Wang D, Wang F, Wang F, Wang G, Wang HJ, Wang H, Wang HG, Wang H, Wang HD, Wang J, Wang J, Wang M, Wang MQ, Wang PY, Wang P, Wang RC, Wang S, Wang TF, Wang X, Wang XJ, Wang XW, Wang X, Wang X, Wang Y, Wang Y, Wang Y, Wang YJ, Wang Y, Wang Y, Wang YT, Wang Y, Wang ZN, Wappner P, Ward C, Ward DM, Warnes G, Watada H, Watanabe Y, Watase K, Weaver TE, Weekes CD, Wei J, Weide T, Weihl CC, Weindl G, Weis SN, Wen L, Wen X, Wen Y, Westermann B, Weyand CM, White AR, White E, Whitton JL, Whitworth AJ, Wiels J, Wild F, Wildenberg ME, Wileman T, Wilkinson DS, Wilkinson S, Willbold D, Williams C, Williams K, Williamson PR, Winklhofer KF, Witkin SS, Wohlgemuth SE, Wollert T, Wolvetang EJ, Wong E, Wong GW, Wong RW, Wong VK, Woodcock EA, Wright KL, Wu C, Wu D, Wu GS, Wu J, Wu J, Wu M, Wu M, Wu S, Wu WK, Wu Y, Wu Z, Xavier CP, Xavier RJ, Xia GX, Xia T, Xia W, Xia Y, Xiao H, Xiao J, Xiao S, Xiao W, Xie CM, Xie Z, Xie Z, Xilouri M, Xiong Y, Xu C, Xu C, Xu F, Xu H, Xu H, Xu J, Xu J, Xu J, Xu L, Xu X, Xu Y, Xu Y, Xu ZX, Xu Z, Xue Y, Yamada T, Yamamoto A, Yamanaka K, Yamashina S, Yamashiro S, Yan B, Yan B, Yan X, Yan Z, Yanagi Y, Yang DS, Yang JM, Yang L, Yang M, Yang PM, Yang P, Yang Q, Yang W, Yang WY, Yang X, Yang Y, Yang Y, Yang Z, Yang Z, Yao MC, Yao PJ, Yao X, Yao Z, Yao Z, Yasui LS, Ye M, Yedvobnick B, Yeganeh B, Yeh ES, Yeyati PL, Yi F, Yi L, Yin XM, Yip CK, Yoo YM, Yoo YH, Yoon SY, Yoshida KI, Yoshimori T, Young KH, Yu H, Yu JJ, Yu JT, Yu J, Yu L, Yu WH, Yu XF, Yu Z, Yuan J, Yuan ZM, Yue BY, Yue J, Yue Z, Zacks DN, Zacksenhaus E, Zaffaroni N, Zaglia T, Zakeri Z, Zecchini V, Zeng J, Zeng M, Zeng Q, Zervos AS, Zhang DD, Zhang F, Zhang G, Zhang GC, Zhang H, Zhang H, Zhang H, Zhang H, Zhang J, Zhang J, Zhang J, Zhang J, Zhang JP, Zhang L, Zhang L, Zhang L, Zhang L, Zhang MY, Zhang X, Zhang XD, Zhang Y, Zhang Y, Zhang Y, Zhang Y, Zhang Y, Zhao M, Zhao WL, Zhao X, Zhao YG, Zhao Y, Zhao Y, Zhao YX, Zhao Z, Zhao ZJ, Zheng D, Zheng XL, Zheng X, Zhivotovsky B, Zhong Q, Zhou GZ, Zhou G, Zhou H, Zhou SF, Zhou XJ, Zhu H, Zhu H, Zhu WG, Zhu W, Zhu XF, Zhu Y, Zhuang SM, Zhuang X, Ziparo E, Zois CE, Zoladek T, Zong WX, Zorzano A, Zughaier SM

Autophagy, 12, 1554-8635, , 2016

PMID:26799652

The brown adipocyte protein CIDEA promotes lipid droplet fusion via a phosphatidic acid-binding amphipathic helix.
Barneda D, Planas-Iglesias J, Gaspar ML, Mohammadyani D, Prasannan S, Dormann D, Han GS, Jesch SA, Carman GM, Kagan V, Parker MG, Ktistakis NT, Dixon AM, Klein-Seetharaman J, Henry S, Christian M

Maintenance of energy homeostasis depends on the highly regulated storage and release of triacylglycerol primarily in adipose tissue and excessive storage is a feature of common metabolic disorders. CIDEA is a lipid droplet (LD)-protein enriched in brown adipocytes promoting the enlargement of LDs which are dynamic, ubiquitous organelles specialized for storing neutral lipids. We demonstrate an essential role in this process for an amphipathic helix in CIDEA, which facilitates embedding in the LD phospholipid monolayer and binds phosphatidic acid (PA). LD pairs are docked by CIDEA trans-complexes through contributions of the N-terminal domain and a C-terminal dimerization region. These complexes, enriched at the LD-LD contact site, interact with the cone-shaped phospholipid PA and likely increase phospholipid barrier permeability, promoting LD fusion by transference of lipids. This physiological process is essential in adipocyte differentiation as well as serving to facilitate the tight coupling of lipolysis and lipogenesis in activated brown fat.

+ View Abstract

eLife, 4, 2050-084X, , 2015

PMID:26609809

Open Access

Structure and flexibility of the endosomal Vps34 complex reveals the basis of its function on membranes.
Rostislavleva K, Soler N, Ohashi Y, Zhang L, Pardon E, Burke JE, Masson GR, Johnson C, Steyaert J, Ktistakis NT, Williams RL

Phosphatidylinositol 3-kinase Vps34 complexes regulate intracellular membrane trafficking in endocytic sorting, cytokinesis, and autophagy. We present the 4.4 angstrom crystal structure of the 385-kilodalton endosomal complex II (PIK3C3-CII), consisting of Vps34, Vps15 (p150), Vps30/Atg6 (Beclin 1), and Vps38 (UVRAG). The subunits form a Y-shaped complex, centered on the Vps34 C2 domain. Vps34 and Vps15 intertwine in one arm, where the Vps15 kinase domain engages the Vps34 activation loop to regulate its activity. Vps30 and Vps38 form the other arm that brackets the Vps15/Vps34 heterodimer, suggesting a path for complex assembly. We used hydrogen-deuterium exchange mass spectrometry (HDX-MS) to reveal conformational changes accompanying membrane binding and identify a Vps30 loop that is critical for the ability of complex II to phosphorylate giant liposomes on which complex I is inactive.

+ View Abstract

Science (New York, N.Y.), 350, 1095-9203, , 2015

PMID:26450213

ERES: sites for autophagosome biogenesis and maturation?
Sanchez-Wandelmer J, Ktistakis NT, Reggiori F

Autophagosomes are the hallmark of autophagy, but despite their central role in this degradative pathway that involves vesicle transport to lysosomes or vacuoles, the mechanism underlying their biogenesis still remains largely unknown. Our current concepts about autophagosome biogenesis are based on models suggesting that a small autonomous cisterna grows into an autophagosome through expansion at its extremities. Recent findings have revealed that endoplasmic reticulum (ER) exit sites (ERES), specialized ER regions where proteins are sorted into the secretory system, are key players in the formation of autophagosomes. Owing to the morphological connection of nascent autophagosomes with the ER, this has raised several questions that challenge our current perception of autophagosome biogenesis, such as are ERES the compartments where autophagosome formation takes place? What is the functional relevance of this connection? Are these compartments providing essential molecules for the generation of autophagosomes and/or are they structural platforms where these vesicles emerge? In this Hypothesis, we discuss recent data that have implicated the ERES in autophagosome biogenesis and we propose two models to describe the possible role of this compartment at different steps in the process of autophagosome biogenesis. This article is part of a Focus on Autophagosome biogenesis. For further reading, please see related articles: 'Membrane dynamics in autophagosome biogenesis' by Sven R. Carlsson and Anne Simonsen (J. Cell Sci. 128, 193-205) and 'WIPI proteins: essential PtdIns3P effectors at the nascent autophagosome' by Tassula Proikas-Cezanne et al. (J. Cell Sci. 128, 207-217).

+ View Abstract

Journal of cell science, 128, 1477-9137, , 2015

PMID:25568152

Open Access

Live-cell imaging for the assessment of the dynamics of autophagosome formation: Focus on early steps.
Karanasios E, Ktistakis NT

Autophagy is a cytosolic degradative pathway, which through a series of complicated membrane rearrangements leads to the formation of a unique double membrane vesicle, the autophagosome. The use of fluorescent proteins has allowed visualizing the autophagosome formation in live cells and in real time, almost 40years after electron microscopy studies observed these structures for the first time. In the last decade, live-cell imaging has been extensively used to study the dynamics of autophagosome formation in cultured mammalian cells. Hereby we will discuss how the live-cell imaging studies have tried to settle the debate about the origin of the autophagosome membrane and how they have described the way different autophagy proteins coordinate in space and time in order to drive autophagosome formation.

+ View Abstract

Methods (San Diego, Calif.), , 1095-9130, , 2014

PMID:25498007

Dynamics of autophagosome formation: a pulse and a sequence of waves.
Ktistakis NT, Karanasios E, Manifava M

Autophagosomes form in eukaryotic cells in response to starvation or to other stress conditions brought about by the unwanted presence in the cytosol of pathogens, damaged organelles or aggregated protein assemblies. The uniqueness of autophagosomes is that they form de novo and that they are the only double-membraned vesicles known in cells, having arisen from flat membrane sheets which have expanded and self-closed. The various steps describing their formation as well as most of the protein and lipid components involved have been identified. Furthermore, the hierarchical relationships among the components are well documented, and the mechanistic rationale for some of these hierarchies has been revealed. In the present review, we try to provide a current view of the process of autophagosome formation in mammalian cells, emphasizing along the way gaps in our knowledge that need additional work.

+ View Abstract

Biochemical Society transactions, 42, 1470-8752, , 2014

PMID:25233420

Imaging autophagy.
Karanasios E, Stapleton E, Manifava M, Ktistakis NT

Autophagy is a membrane-trafficking pathway activated to deliver cytosolic material for degradation to lysosomes through a novel membrane compartment, the autophagosome. Fluorescence microscopy is the most common method used to visualize proteins inside cells, and it is widely used in the autophagy field. To distinguish it from the cellular background, the protein of interest (POI) is either fused with a genetically encoded fluorescent protein or stained with an antibody that is conjugated to an inorganic fluorescent compound. Genetic tagging of the POI allows its visualization in live cells, while immunostaining of the POI requires the fixation of cells and the permeabilization of cell membranes. Here we describe detailed protocols on how to visualize autophagy dynamics using fluorescence microscopy in live and fixed cells. We discuss the critical parameters of each technique, their advantages, and why the robustness is increased when they are used in tandem.

+ View Abstract

Current protocols in cytometry / editorial board, J. Paul Robinson, managing editor ... [et al.], 69, 1934-9300, , 2014

PMID:24984962

The immune system GTPase GIMAP6 interacts with the Atg8 homologue GABARAPL2 and is recruited to autophagosomes.
Pascall JC, Rotondo S, Mukadam AS, Oxley D, Webster J, Walker SA, Piron J, Carter C, Ktistakis NT, Butcher GW

The GIMAPs (GTPases of the immunity-associated proteins) are a family of small GTPases expressed prominently in the immune systems of mammals and other vertebrates. In mammals, studies of mutant or genetically-modified rodents have indicated important roles for the GIMAP GTPases in the development and survival of lymphocytes. No clear picture has yet emerged, however, of the molecular mechanisms by which they perform their function(s). Using biotin tag-affinity purification we identified a major, and highly specific, interaction between the human cytosolic family member GIMAP6 and GABARAPL2, one of the mammalian homologues of the yeast autophagy protein Atg8. Chemical cross-linking studies performed on Jurkat T cells, which express both GIMAP6 and GABARAPL2 endogenously, indicated that the two proteins in these cells readily associate with one another in the cytosol under normal conditions. The GIMAP6-GABARAPL2 interaction was disrupted by deletion of the last 10 amino acids of GIMAP6. The N-terminal region of GIMAP6, however, which includes a putative Atg8-family interacting motif, was not required. Over-expression of GIMAP6 resulted in increased levels of endogenous GABARAPL2 in cells. After culture of cells in starvation medium, GIMAP6 was found to localise in punctate structures with both GABARAPL2 and the autophagosomal marker MAP1LC3B, indicating that GIMAP6 re-locates to autophagosomes on starvation. Consistent with this finding, we have demonstrated that starvation of Jurkat T cells results in the degradation of GIMAP6. Whilst these findings raise the possibility that the GIMAPs play roles in the regulation of autophagy, we have been unable to demonstrate an effect of GIMAP6 over-expression on autophagic flux.

+ View Abstract

PloS one, 8, 1932-6203, , 2013

PMID:24204963

Open Access

Omegasomes: PI3P platforms that manufacture autophagosomes.
Roberts R, Ktistakis NT

Autophagy is a conserved survival pathway, which cells and tissues will activate during times of stress. It is characterized by the formation of double-membrane vesicles called autophagosomes inside the cytoplasm. The molecular mechanisms and the signalling components involved require specific control to ensure correct activation. The present chapter describes the formation of autophagosomes from within omegasomes, newly identified membrane compartments enriched in PI3P (phosphatidylinositol 3-phosphate) that serve as platforms for the formation of at least some autophagosomes. We discuss the signalling events required to nucleate the formation of omegasomes as well as the protein complexes involved.

+ View Abstract

Essays in biochemistry, 55, 1744-1358, , 2013

PMID:24070468

Dynamic association of the ULK1 complex with omegasomes during autophagy induction.
Karanasios E, Stapleton E, Manifava M, Kaizuka T, Mizushima N, Walker SA, Ktistakis NT

Induction of autophagy requires the ULK1 protein kinase complex and the Vps34 lipid kinase complex. PtdIns3P synthesised by Vps34 accumulates in omegasomes, membrane extensions of the ER within which some autophagosomes form. The ULK1 complex is thought to target autophagosomes independently of PtdIns3P, and its functional relationship to omegasomes is unclear. Here we show that the ULK1 complex colocalises with omegasomes in a PtdIns3P-dependent way. Live-cell imaging of Atg13 (a ULK1 complex component), omegasomes and LC3 establishes and annotates for the first time a complete sequence of steps leading to autophagosome formation, as follows. Upon starvation, the ULK1 complex forms puncta associated with the ER and sporadically with mitochondria. If PtdIns3P is available, these puncta become omegasomes. Subsequently, the ULK1 complex exits omegasomes and autophagosomes bud off. If PtdIns3P is unavailable, ULK1 puncta are greatly reduced in number and duration. Atg13 contains a region with affinity for acidic phospholipids, required for translocation to punctate structures and autophagy progression.

+ View Abstract

Journal of cell science, 126, 1477-9137, , 2013

PMID:24013547

Open Access

Differential isolation and identification of PI(3)P and PI(3,5)P2 binding proteins from Arabidopsis thaliana using an agarose-phosphatidylinositol-phosphate affinity chromatography.
D Oxley, N Ktistakis, T Farmaki

A phosphatidylinositol-phosphate affinity chromatographic approach combined with mass spectrometry was used in order to identify novel PI(3)P and PI(3,5)P2 binding proteins from Arabidopsis thaliana suspension cell extracts. Most of the phosphatidylinositol-phosphate interacting candidates identified from this differential screening are characterized by lysine/arginine rich patches. Direct phosphoinositide binding was identified for important membrane trafficking regulators as well as protein quality control proteins such as the ATG18p orthologue involved in autophagosome formation and the lipid Sec14p like transfer protein. A pentatricopeptide repeat (PPR) containing protein was shown to directly bind to PI(3,5)P2 but not to PI(3)P. PIP chromatography performed using extracts obtained from high salt (0.4M and 1M NaCl) pretreated suspensions showed that the association of an S5-1 40S ribosomal protein with both PI(3)P and PI(3,5)P2 was abolished under salt stress whereas salinity stress induced an increase in the phosphoinositide association of the DUF538 domain containing protein SVB, associated with trichome size. Additional interacting candidates were co-purified with the phosphoinositide bound proteins. Binding of the COP9 signalosome, the heat shock proteins, and the identified 26S proteasomal subunits, is suggested as an indirect effect of their interaction with other proteins directly bound to the PI(3)P and the PI(3,5)P2 phosphoinositides.

+ View Abstract

Journal of proteomics, , , , 2013

PMID:24007659
DOI: 10.1016/j.jprot.2013.08.020

Live cell imaging of early autophagy events: omegasomes and beyond.
E Karanasios, E Stapleton, SA Walker, M Manifava, NT Ktistakis

Autophagy is a cellular response triggered by the lack of nutrients, especially the absence of amino acids. Autophagy is defined by the formation of double membrane structures, called autophagosomes, that sequester cytoplasm, long-lived proteins and protein aggregates, defective organelles, and even viruses or bacteria. Autophagosomes eventually fuse with lysosomes leading to bulk degradation of their content, with the produced nutrients being recycled back to the cytoplasm. Therefore, autophagy is crucial for cell homeostasis, and dysregulation of autophagy can lead to disease, most notably neurodegeneration, ageing and cancer. Autophagosome formation is a very elaborate process, for which cells have allocated a specific group of proteins, called the core autophagy machinery. The core autophagy machinery is functionally complemented by additional proteins involved in diverse cellular processes, e.g. in membrane trafficking, in mitochondrial and lysosomal biology. Coordination of these proteins for the formation and degradation of autophagosomes constitutes the highly dynamic and sophisticated response of autophagy. Live cell imaging allows one to follow the molecular contribution of each autophagy-related protein down to the level of a single autophagosome formation event and in real time, therefore this technique offers a high temporal and spatial resolution. Here we use a cell line stably expressing GFP-DFCP1, to establish a spatial and temporal context for our analysis. DFCP1 marks omegasomes, which are precursor structures leading to autophagosomes formation. A protein of interest (POI) can be marked with either a red or cyan fluorescent tag. Different organelles, like the ER, mitochondria and lysosomes, are all involved in different steps of autophagosome formation, and can be marked using a specific tracker dye. Time-lapse microscopy of autophagy in this experimental set up, allows information to be extracted about the fourth dimension, i.e. time. Hence we can follow the contribution of the POI to autophagy in space and time.

+ View Abstract

Journal of visualized experiments : JoVE, , 77, , 2013

PMID:23929131
DOI: 10.3791/50484

Characteristics and requirements of basal autophagy in HEK 293 cells.
Musiwaro P, Smith M, Manifava M, Walker SA, Ktistakis NT

Basal autophagy-here defined as macroautophagic activity during cellular growth in normal medium containing amino acids and serum-appears to be highly active in many cell types and in animal tissues. Here we characterized this pathway in mammalian HEK 293 cells. First, we examined, side by side, three compounds that are widely used to reveal basal autophagy by blocking maturation of autophagosomes: bafilomycin A 1 (BafA1), chloroquine and vinblastine. Only BafA1 appeared to be without complicating side effects. Chloroquine partially inhibited mechanistic target of rapamycin (MTOR) activity, which would induce autophagy induction as well as block autophagosome maturation. Vinblastine caused the distribution of early omegasome components into punctate phagophore assembly sites, and therefore it would also induce autophagy, complicating interpretation. Basal autophagy was significantly sensitive to inhibition by wortmannin, and therefore required formation of phosphatidylinositol 3-phosphate (PtdIns3P), but it was twice as resistant to wortmannin as starvation-induced autophagy. We also determined that basal autophagy was significantly suppressed by MTOR activation brought about by overexpression of RHEB or activated RAGs. Finally we investigated the spatial relationship of nascent autophagosomes to the endoplasmic reticulum (ER) or to mitochondria by live imaging experiments under conditions that reveal basal autophagy (with BafA1 treatment), or upon MTOR inactivation (which would result in autophagy induction). Side-by-side comparison showed that under both basal and induced autophagy, 100% of autophagosomes first appeared in close proximity to ER strands. In parallel measurements, 40% were in close proximity to mitochondria under both conditions. We concluded that in HEK 293 cells, basal autophagy is mechanistically similar to that induced by MTOR inactivation in all aspects examined.

+ View Abstract

Autophagy, 9, 1554-8635, , 2013

PMID:23800949

PIPing on lysosome tubes.
NT Ktistakis, SA Tooze

The EMBO journal, 32, 3, , 2013

PMID:23314746
DOI: 10.1038/emboj.2012.355

Open Access

The Arabidopsis thaliana immunophilin ROF1 directly interacts with PI(3)P and PI(3,5)P2 and affects germination under osmotic stress.
D Karali, D Oxley, J Runions, N Ktistakis, T Farmaki

A direct interaction of the Arabidopsis thaliana immunophilin ROF1 with phosphatidylinositol-3-phosphate and phosphatidylinositol-3,5-bisphosphate was identified using a phosphatidylinositol-phosphate affinity chromatography of cell suspension extracts, combined with a mass spectrometry (nano LC ESI-MS/MS) analysis. The first FK506 binding domain was shown sufficient to bind to both phosphatidylinositol-phosphate stereoisomers. GFP-tagged ROF1 under the control of a 35S promoter was localised in the cytoplasm and the cell periphery of Nicotiana tabacum leaf explants. Immunofluorescence microscopy of Arabidopsis thaliana root tips verified its cytoplasmic localization and membrane association and showed ROF1 localization in the elongation zone which was expanded to the meristematic zone in plants grown on high salt media. Endogenous ROF1 was shown to accumulate in response to high salt treatment in Arabidopsis thaliana young leaves as well as in seedlings germinated on high salt media (0.15 and 0.2 M NaCl) at both an mRNA and protein level. Plants over-expressing ROF1, (WSROF1OE), exhibited enhanced germination under salinity stress which was significantly reduced in the rof1(-) knock out mutants and abolished in the double mutants of ROF1 and of its interacting homologue ROF2 (WSrof1(-)/2(-)). Our results show that ROF1 plays an important role in the osmotic/salt stress responses of germinating Arabidopsis thaliana seedlings and suggest its involvement in salinity stress responses through a phosphatidylinositol-phosphate related protein quality control pathway.

+ View Abstract

PloS one, 7, 11, , 2012

PMID:23133621
DOI: 10.1371/journal.pone.0048241

Open Access

How phosphoinositide 3-phosphate controls growth downstream of amino acids and autophagy downstream of amino acid withdrawal.
NT Ktistakis, M Manifava, P Schoenfelder, S Rotondo

The simple phosphoinositide PtdIns3P has been shown to control cell growth downstream of amino acid signalling and autophagy downstream of amino acid withdrawal. These opposing effects depend in part on the existence of distinct complexes of Vps34 (vacuolar protein sorting 34), the kinase responsible for the majority of PtdIns3P synthesis in cells: one complex is activated after amino acid withdrawal to induce autophagy and another regulates mTORC1 (mammalian target of rapamycin complex 1) activation when amino acids are present. However, lipid-dependent signalling almost always exhibits a spatial dimension, related to the site of formation of the lipid signal. In the case of PtdIns3P-regulated autophagy induction, recent data suggest that PtdIns3P accumulates in a membrane compartment dynamically connected to the endoplasmic reticulum that constitutes a platform for the formation of some autophagosomes. For PtdIns3P-regulated mTORC1 activity, a spatial context is not yet known: several possibilities can be envisaged based on the known effects of PtdIns3P on the endocytic system and on recent data suggesting that activation of mTORC1 depends on its localization on lysosomes.

+ View Abstract

Biochemical Society transactions, 40, 1, , 2012

PMID:22260663
DOI: 10.1042/BST20110684

Coronavirus nsp6 proteins generate autophagosomes from the endoplasmic reticulum via an omegasome intermediate.
EM Cottam, HJ Maier, M Manifava, LC Vaux, P Chandra-Schoenfelder, W Gerner, P Britton, NT Ktistakis, T Wileman

Autophagy is a cellular response to starvation which generates autophagosomes to carry cellular organelles and long-lived proteins to lysosomes for degradation. Degradation through autophagy can provide an innate defence against virus infection, or conversely autophagosomes can promote infection by facilitating assembly of replicase proteins. We demonstrate that the avian coronavirus, Infectious Bronchitis Virus (IBV) activates autophagy. A screen of individual IBV non-structural proteins (nsps) showed that autophagy was activated by IBV nsp6. This property was shared with nsp6 of mammalian coronaviruses Mouse Hepatitis Virus, and Severe Acute Respiratory Syndrome Virus, and the equivalent nsp5-7 of the arterivirus Porcine Reproductive and Respiratory Syndrome Virus. These multiple-spanning transmembrane proteins located to the endoplasmic reticulum (ER) where they generated Atg5 and LC3II-positive vesicles, and vesicle formation was dependent on Atg5 and class III PI3 kinase. The vesicles recruited double FYVE-domain containing protein (DFCP) indicating localised concentration of phosphatidylinositol 3 phosphate, and therefore shared many features with omegasomes formed from the ER in response to starvation. Omegasomes induced by viral nsp6 matured into autophagosomes that delivered LC3 to lysosomes and therefore recruited and recycled the proteins needed for autophagosome nucleation, expansion, cellular trafficking and delivery of cargo to lysosomes. The coronavirus nsp6 proteins activated omegasome and autophagosome formation independently of starvation, but activation did not involve direct inhibition of mTOR signalling, activation of sirtuin1 or induction of ER stress.

+ View Abstract

Autophagy, 7, 11, , 2011

PMID:21799305
DOI: 10.4161/auto.7.11.16642

Open Access

The autoimmunity-related GIMAP5 GTPase is a lysosome-associated protein.
VW Wong, AE Saunders, A Hutchings, JC Pascall, C Carter, NA Bright, SA Walker, NT Ktistakis, GW Butcher

A mutation in the rat GIMAP5 gene predisposes for autoimmunity, most famously in the BB rat model of autoimmune type 1 diabetes mellitus. This mutation is associated with severe peripheral T lymphopenia, as is mutation of the same gene in mice, but the mechanism by which GIMAP5 normally protects T cells from death is unknown. GIMAP5 is a putative small GTPase, a class of proteins which often fulfil their functions in the vicinity of cellular membranes. The objective of this study was to determine the normal intracellular location of GIMAP5 in lymphoid cells. Combining studies in rat, mouse and human systems, novel monoclonal antibodies (mAbs) were used to examine the localization of GIMAP5 and the closely-related protein, GIMAP1, in lymphoid cells by means of confocal microscopy and sub-cellular fractionation combined with immunoblotting. Additionally, human Jurkat T cells that inducibly express epitope-tagged GIMAP5 were established and used in electron microscopy (EM). Endogenous GIMAP5 was found to be located in a membraneous compartment/s which was also detected by established markers of lysosomes. GIMAP1, by contrast, was found to be located in the Golgi apparatus. EM studies of the inducible Jurkat T cells also found GIMAP5 in lysosomes and, in addition, in multivesicular bodies. This study establishes that the endogenous location of GIMAP5 is in lysosomes and related compartments and provides a clearer context for hypotheses about its mechanism of action.

+ View Abstract

Self/nonself, 1, 3, , 2010

PMID:21487483
DOI: 10.4161/self.1.3.12819

Open Access

Lipid signaling and homeostasis: PA- is better than PA-H, but what about those PIPs?
NT Ktistakis

Although cellular membranes are composed of hundreds of distinct lipid species, the lipid composition is maintained within a narrow range. The regulatory circuit responsible for this homeostasis in yeast depends on a membrane-bound transcriptional repressor that translocates to the nucleus in response to the abundance of its lipid ligand on the membrane. Feedback control in this system is provided because the lipid ligand is also an end product of the activity of the transcription factor. This basic design is also evident in higher eukaryotes such as Drosophila and mammals, but with important differences in the lipid being sensed, the composition of the sensors, and the fine-tuning of the response. New work indicates that regulation of intracellular pH levels in yeast by glucose availability may fine-tune the binding of the repressor to its lipid ligand, providing a mechanism that connects phospholipid metabolism to nutrient sensing. The importance of pH effects in this pathway raises the possibility that additional lipid-signaling pathways may be regulated by the protonation state of the lipid or its effector.

+ View Abstract

Science signaling, 3, 151, , 2010

PMID:21139136
DOI: 10.1126/scisignal.3151pe46

Antibacterial autophagy occurs at PI(3)P-enriched domains of the endoplasmic reticulum and requires Rab1 GTPase.
J Huang, CL Birmingham, S Shahnazari, J Shiu, YT Zheng, AC Smith, KG Campellone, WD Heo, S Gruenheid, T Meyer, MD Welch, NT Ktistakis, PK Kim, DJ Klionsky, JH Brumell

Autophagy mediates the degradation of cytoplasmic components in eukaryotic cells and plays a key role in immunity. The mechanism of autophagosome formation is not clear. Here we examined two potential membrane sources for antibacterial autophagy: the ER and mitochondria. DFCP1, a marker of specialized ER domains known as 'omegasomes,' associated with Salmonella-containing autophagosomes via its PtdIns(3)P and ER-binding domains, while a mitochondrial marker (cytochrome b5-GFP) did not. Rab1 also localized to autophagosomes, and its activity was required for autophagosome formation, clearance of protein aggregates and peroxisomes, and autophagy of Salmonella. Overexpression of Rab1 enhanced antibacterial autophagy. The role of Rab1 in antibacterial autophagy was independent of its role in ER-to-Golgi transport. Our data suggest that antibacterial autophagy occurs at omegasomes and reveal that the Rab1 GTPase plays a crucial role in mammalian autophagy.

+ View Abstract

Autophagy, 7, 1, , 2011

PMID:20980813

Open Access

What is the advantage of a transient precursor in autophagosome biogenesis?
NT Ktistakis, S Andrews, J Long

We have recently proposed that some autophagosomes are formed within omegasomes, membrane sites connected to the endoplasmic reticulum and enriched in phosphatidylinositol 3-phosphate. In order to understand if there is any biological advantage to having such a precursor in autophagosome biogenesis, we generated a simple computer program that simulates omegasome and autophagosome formation under a variety of conditions. We concluded from running this simulation that having a transient precursor permits a bigger dynamic range of the autophagic response and allows a more efficient approach to steady state after autophagy stimulation.

+ View Abstract

Autophagy, 7, 1, , 2011

PMID:20935487
DOI: 10.1083/jcb.200803137

Open Access

Autophagosome formation in mammalian cells.
C Burman, NT Ktistakis

Autophagy is a fundamental intracellular trafficking pathway conserved from yeast to mammals. It is generally thought to play a pro-survival role, and it can be up regulated in response to both external and intracellular factors, including amino acid starvation, growth factor withdrawal, low cellular energy levels, endoplasmic reticulum (ER) stress, hypoxia, oxidative stress, pathogen infection, and organelle damage. During autophagy initiation a portion of the cytosol is surrounded by a flat membrane sheet known as the isolation membrane or phagophore. The isolation membrane then elongates and seals itself to form an autophagosome. The autophagosome fuses with normal endocytic traffic to mature into a late autophagosome, before fusing with lysosomes. The molecular machinery that enables formation of an autophagosome in response to the various autophagy stimuli is almost completely identified in yeast and-thanks to the observed conservation-is also being rapidly elucidated in higher eukaryotes including mammals. What are less clear and currently under intense investigation are the mechanism by which these various autophagy components co-ordinate in order to generate autophagosomes. In this review, we will discuss briefly the fundamental importance of autophagy in various pathophysiological states and we will then review in detail the various players in early autophagy. Our main thesis will be that a conserved group of heteromeric protein complexes and a relatively simple signalling lipid are responsible for the formation of autophagosomes in mammalian cells.

+ View Abstract

Seminars in immunopathology, 32, 4, , 2010

PMID:20740284
DOI: 10.1007/s00281-010-0222-z

Autophagy requires endoplasmic reticulum targeting of the PI3-kinase complex via Atg14L.
K Matsunaga, E Morita, T Saitoh, S Akira, NT Ktistakis, T Izumi, T Noda, T Yoshimori

Autophagy is a catabolic process that allows cells to digest their cytoplasmic constituents via autophagosome formation and lysosomal degradation. Recently, an autophagy-specific phosphatidylinositol 3-kinase (PI3-kinase) complex, consisting of hVps34, hVps15, Beclin-1, and Atg14L, has been identified in mammalian cells. Atg14L is specific to this autophagy complex and localizes to the endoplasmic reticulum (ER). Knockdown of Atg14L leads to the disappearance of the DFCP1-positive omegasome, which is a membranous structure closely associated with both the autophagosome and the ER. A point mutation in Atg14L resulting in defective ER localization was also defective in the induction of autophagy. The addition of the ER-targeting motif of DFCP1 to this mutant fully complemented the autophagic defect in Atg14L knockout embryonic stem cells. Thus, Atg14L recruits a subset of class III PI3-kinase to the ER, where otherwise phosphatidylinositol 3-phosphate (PI3P) is essentially absent. The Atg14L-dependent appearance of PI3P in the ER makes this organelle the platform for autophagosome formation.

+ View Abstract

The Journal of cell biology, 190, 4, , 2010

PMID:20713597
DOI: 10.1083/jcb.200911141

Open Access

Regulation of autophagy by phosphatidylinositol 3-phosphate.
C Burman, NT Ktistakis

The simple phosphoinositide phosphatidylinositol 3-phosphate (PI(3)P) has been known to have important functions in endocytic and phagocytic traffic, and to be required for the autophagic pathway. In all of these settings, PI(3)P appears to create platforms that serve to recruit specific effectors for membrane trafficking events. In autophagy, PI(3)P may form the platform for autophagosome biogenesis.

+ View Abstract

FEBS letters, 584, 7, , 2010

PMID:20074568
DOI: 10.1016/j.febslet.2010.01.011

Open Access

Modulation of local PtdIns3P levels by the PI phosphatase MTMR3 regulates constitutive autophagy.
N Taguchi-Atarashi, M Hamasaki, K Matsunaga, H Omori, NT Ktistakis, T Yoshimori, T Noda

Autophagy is a catabolic process that delivers cytoplasmic material to the lysosome for degradation. The mechanisms regulating autophagosome formation and size remain unclear. Here, we show that autophagosome formation was triggered by the overexpression of a dominant-negative inactive mutant of Myotubularin-related phosphatase 3 (MTMR3). Mutant MTMR3 partially localized to autophagosomes, and PtdIns3P and two autophagy-related PtdIns3P-binding proteins, GFP-DFCP1 and GFP-WIPI-1alpha (WIPI49/Atg18), accumulated at sites of autophagosome formation. Knock-down of MTMR3 increased autophagosome formation, and overexpression of wild-type MTMR3 led to significantly smaller nascent autophagosomes and a net reduction in autophagic activity. These results indicate that autophagy initiation depends on the balance between PI 3-kinase and PI 3-phosphatase activity. Local levels of PtdIns3P at the site of autophagosome formation determine autophagy initiation and the size of the autophagosome membrane structure.

+ View Abstract

Traffic (Copenhagen, Denmark), 11, 4, , 2010

PMID:20059746
DOI: 10.1111/j.1600-0854.2010.01034.x

Synthesis and biological evaluation of phosphatidylinositol phosphate affinity probes.
SJ Conway, J Gardiner, SJ Grove, MK Johns, ZY Lim, GF Painter, DE Robinson, C Schieber, JW Thuring, LS Wong, MX Yin, AW Burgess, B Catimel, PT Hawkins, NT Ktistakis, LR Stephens, AB Holmes

The synthesis of the complete family of phosphatidylinositol phosphate analogues (PIPs) from five key core intermediates A-E is described. These core compounds were obtained from myo-inositol orthoformate 1 via regioselective DIBAL-H and trimethylaluminium-mediated cleavages and a resolution-protection process using camphor acetals 10. Coupling of cores A-E with phosphoramidites 34 and 38, derived from the requisite protected lipid side chains, afforded the fully-protected PIPs. Removal of the remaining protecting groups was achieved via hydrogenolysis using palladium black or palladium hydroxide on carbon in the presence of sodium bicarbonate to afford the complete family of dipalmitoyl- and amino-PIP analogues 42, 45, 50, 51, 58, 59, 67, 68, 76, 77, 82, 83, 92, 93, 99 and 100. Investigations using affinity probes incorporating these compounds have identified novel proteins involved in the PI3K intracellular signalling network and have allowed a comprehensive proteomic analysis of phosphoinositide interacting proteins.

+ View Abstract

Organic & biomolecular chemistry, 8, 1, , 2010

PMID:20024134
DOI: 10.1039/b913399b

Galpha(q)-mediated plasma membrane translocation of sphingosine kinase-1 and cross-activation of S1P receptors.
M ter Braak, K Danneberg, K Lichte, K Liphardt, NT Ktistakis, SM Pitson, T Hla, KH Jakobs, D Meyer zu Heringdorf

Sphingosine-1-phosphate (S1P), formed by sphingosine kinases (SphKs), regulates cellular proliferation and migration by acting as an agonist at specific receptors or intracellularly. Since S1P's effects are probably dependent on subcellular localization of its formation and degradation, we have studied the influence of G protein-coupled receptors on the localization of SphK1. Activation of Gq-coupled receptors induced a profound, rapid (half-life 3-5 s) and long-lasting (> 2 h) translocation of SphK1 to the plasma membrane. This was mimicked by expression of constitutively active G protein alpha-subunits specifically of the Gq family. Classical Gq signalling pathways, or phosphorylation at Ser225, phospholipase D and Ca2+/calmodulin were not involved in M3 receptor-induced SphK1 translocation in HEK-293 cells. Translocation was associated with S1P receptor internalization, which was dependent on catalytic activity of SphK1 and S1P receptor binding and thus resulted from S1P receptor cross-activation. It is concluded that SphK1 is an important effector of Gq-coupled receptors, linking them via cross-activation of S1P receptors to G(i) and G12/13 signalling pathways.

+ View Abstract

Biochimica et biophysica acta, 1791, 5, , 2009

PMID:19830907

Rhabdomere biogenesis in Drosophila photoreceptors is acutely sensitive to phosphatidic acid levels.
P Raghu, E Coessens, M Manifava, P Georgiev, T Pettitt, E Wood, I Garcia-Murillas, H Okkenhaug, D Trivedi, Q Zhang, A Razzaq, O Zaid, M Wakelam, CJ O'Kane, N Ktistakis

Phosphatidic acid (PA) is postulated to have both structural and signaling functions during membrane dynamics in animal cells. In this study, we show that before a critical time period during rhabdomere biogenesis in Drosophila melanogaster photoreceptors, elevated levels of PA disrupt membrane transport to the apical domain. Lipidomic analysis shows that this effect is associated with an increase in the abundance of a single, relatively minor molecular species of PA. These transport defects are dependent on the activation state of Arf1. Transport defects via PA generated by phospholipase D require the activity of type I phosphatidylinositol (PI) 4 phosphate 5 kinase, are phenocopied by knockdown of PI 4 kinase, and are associated with normal endoplasmic reticulum to Golgi transport. We propose that PA levels are critical for apical membrane transport events required for rhabdomere biogenesis.

+ View Abstract

The Journal of cell biology, 185, 1, , 2009

PMID:19349583
DOI: 10.1083/jcb.200807027

Open Access

Emerging findings from studies of phospholipase D in model organisms (and a short update on phosphatidic acid effectors).
P Raghu, M Manifava, J Coadwell, NT Ktistakis

Phospholipase D (PLD) catalyses the hydrolysis of phosphatidylcholine to generate phosphatidic acid and choline. Historically, much PLD work has been conducted in mammalian settings although genes encoding enzymes of this family have been identified in all eukaryotic organisms. Recently, important insights on PLD function are emerging from work in yeast, but much less is known about PLD in other organisms. In this review we will summarize what is known about phospholipase D in several model organisms, including C. elegans, D. discoideum, D. rerio and D. melanogaster. In the cases where knockouts are available (C. elegans, Dictyostelium and Drosophila) the PLD gene(s) appear not to be essential for viability, but several studies are beginning to identify pathways where this activity has a role. Given that the proteins in model organisms are very similar to their mammalian counterparts, we expect that future studies in model organisms will complement and extend ongoing work in mammalian settings. At the end of this review we will also provide a short update on phosphatidic acid targets, a topic last reviewed in 2006.

+ View Abstract

Biochimica et biophysica acta, 1791, 9, , 2009

PMID:19345277
DOI: 10.1016/j.bbalip.2009.03.013

The sphingosine 1-phosphate receptor 5 and sphingosine kinases 1 and 2 are localised in centrosomes: possible role in regulating cell division.
L Gillies, SC Lee, JS Long, N Ktistakis, NJ Pyne, S Pyne

We show here that the endogenous sphingosine 1-phosphate 5 receptor (S1P(5), a G protein coupled receptor (GPCR) whose natural ligand is sphingosine 1-phosphate (S1P)) and sphingosine kinases 1 and 2 (SK1 and SK2), which catalyse formation of S1P, are co-localised in the centrosome of mammalian cells, where they may participate in regulating mitosis. The centrosome is a site for active GTP-GDP cycling involving the G-protein, G(i) and tubulin, which are required for spindle pole organization and force generation during cell division. Therefore, the presence of S1P(5) (which normally functions as a plasma membrane guanine nucleotide exchange factor, GEF) and sphingosine kinases in the centrosome might suggest that S1P(5) may function as a ligand activated GEF in regulating G-protein-dependent spindle formation and mitosis. The addition of S1P to cells inhibits trafficking of S1P(5) to the centrosome, suggesting a dynamic shuttling endocytic mechanism controlled by ligand occupancy of cell surface receptor. We therefore propose that the centrosomal S1P(5) receptor might function as an intracellular target of S1P linked to regulation of mitosis.

+ View Abstract

Cellular signalling, 21, 5, , 2009

PMID:19211033
DOI: 10.1016/j.cellsig.2009.01.023

PA binding of phosphatidylinositol 4-phosphate 5-kinase.
C Stace, M Manifava, C Delon, J Coadwell, S Cockcroft, NT Ktistakis

Advances in enzyme regulation, 48, , , 2008

PMID:18167315
DOI: 10.1016/j.advenzreg.2007.11.008

Phosphatidic acid- and phosphatidylserine-binding proteins.
CL Stace, NT Ktistakis

Phosphatidic acid and phosphatidylserine are negatively charged abundant phospholipids with well-recognized structural roles in cellular membranes. They are also signaling lipids since their regulated formation (or appearance) can constitute an important signal for downstream responses. The list of potential effectors for these lipids is expanding rapidly and includes proteins involved in virtually all aspects of cellular regulation. Because it is not always clear whether these effectors recognize the specific phospholipids or a general negatively-charged membrane environment, questions about specificity must be addressed on a case by case basis. In this review we present an up to date list of potential phosphatidic acid- and phosphatidylserine-binding proteins.

+ View Abstract

Biochimica et biophysica acta, 1761, 8, , 2006

PMID:16624617
DOI: 10.1016/j.bbalip.2006.03.006

Sphingosine kinase 1 is an intracellular effector of phosphatidic acid.
C Delon, M Manifava, E Wood, D Thompson, S Krugmann, S Pyne, NT Ktistakis

Sphingosine kinase 1 (SK1) phosphorylates sphingosine to generate sphingosine 1-phosphate (S1P). Because both substrate and product of the enzyme are potentially important signaling molecules, the regulation of SK1 is of considerable interest. We report that SK1, which is ordinarily a cytosolic enzyme, translocates in vivo and in vitro to membrane compartments enriched in phosphatidic acid (PA), the lipid product of phospholipase D. This translocation depends on direct interaction of SK1 with PA, because recombinant purified enzyme shows strong affinity for pure PA coupled to Affi-Gel. The SK1-PA interaction maps to the C terminus of SK1 and is independent of catalytic activity or of the diacylglycerol kinase-like domain of the enzyme. Thus SK1 constitutes a novel, physiologically relevant PA effector.

+ View Abstract

The Journal of biological chemistry, 279, 43, , 2004

PMID:15310762
DOI: 10.1074/jbc.M405771200

Open Access