Life Sciences Research for Lifelong Health


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Title / Authors / Details Open Access Download

Genome-Wide Measurement and Computational Analysis of Transcription Factor Binding and Chromatin Accessibility in Lymphocytes.
Sadiyah MF, Roychoudhuri R

Cells of the adaptive immune system, including CD4 and CD8 T cells, as well as B cells, possess the ability to undergo dynamic changes in population size, differentiation state, and function to counteract diverse and temporally stochastic threats from the external environment. To achieve this, lymphocytes must be able to rapidly control their gene-expression programs in a cell-type-specific manner and in response to extrinsic signals. Such capacity is provided by transcription factors (TFs), which bind to the available repertoire of regulatory DNA elements in distinct lymphocyte subsets to program cell-type-specific gene expression. Here we provide a set of protocols that utilize massively parallel sequencing-based approaches to map genome-wide TF-binding sites and accessible chromatin, with consideration of the unique aspects and technical issues facing their application to lymphocytes. We show how to computationally validate and analyze aligned data to map differentially enriched/accessible sites, identify enriched DNA sequence motifs, and detect the position of nucleosomes adjacent to accessible DNA elements. These techniques, when applied to immune cells, can enhance our understanding of how gene-expression programs are controlled within lymphocytes to coordinate immune function in homeostasis and disease. © 2019 by John Wiley & Sons, Inc.

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Current protocols in immunology, 126, 1934-368X, e84, 2019

PMID: 31483104

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.

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EMBO reports, , 1469-3178, e47734, 2019

PMID: 31448519

Distinct Molecular Trajectories Converge to Induce Naive Pluripotency.
Stuart HT, Stirparo GG, Lohoff T, Bates LE, Kinoshita M, Lim CY, Sousa EJ, Maskalenka K, Radzisheuskaya A, Malcolm AA, Alves MRP, Lloyd RL, Nestorowa S, Humphreys P, Mansfield W, Reik W, Bertone P, Nichols J, Göttgens B, Silva JCR

Understanding how cell identity transitions occur and whether there are multiple paths between the same beginning and end states are questions of wide interest. Here we show that acquisition of naive pluripotency can follow transcriptionally and mechanistically distinct routes. Starting from post-implantation epiblast stem cells (EpiSCs), one route advances through a mesodermal state prior to naive pluripotency induction, whereas another transiently resembles the early inner cell mass and correspondingly gains greater developmental potency. These routes utilize distinct signaling networks and transcription factors but subsequently converge on the same naive endpoint, showing surprising flexibility in mechanisms underlying identity transitions and suggesting that naive pluripotency is a multidimensional attractor state. These route differences are reconciled by precise expression of Oct4 as a unifying, essential, and sufficient feature. We propose that fine-tuned regulation of this "transition factor" underpins multidimensional access to naive pluripotency, offering a conceptual framework for understanding cell identity transitions.

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Cell stem cell, , 1875-9777, , 2019

PMID: 31422912

Screening for genes that accelerate the epigenetic aging clock in humans reveals a role for the H3K36 methyltransferase NSD1.
Martin-Herranz DE, Aref-Eshghi E, Bonder MJ, Stubbs TM, Choufani S, Weksberg R, Stegle O, Sadikovic B, Reik W, Thornton JM

Epigenetic clocks are mathematical models that predict the biological age of an individual using DNA methylation data and have emerged in the last few years as the most accurate biomarkers of the aging process. However, little is known about the molecular mechanisms that control the rate of such clocks. Here, we have examined the human epigenetic clock in patients with a variety of developmental disorders, harboring mutations in proteins of the epigenetic machinery.

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Genome biology, 20, 1474-760X, 146, 2019

PMID: 31409373

ZFP57 regulation of transposable elements and gene expression within and beyond imprinted domains.
Shi H, Strogantsev R, Takahashi N, Kazachenka A, Lorincz MC, Hemberger M, Ferguson-Smith AC

KRAB zinc finger proteins (KZFPs) represent one of the largest families of DNA-binding proteins in vertebrate genomes and appear to have evolved to silence transposable elements (TEs) including endogenous retroviruses through sequence-specific targeting of repressive chromatin states. ZFP57 is required to maintain the post-fertilization DNA methylation memory of parental origin at genomic imprints. Here we conduct RNA-seq and ChIP-seq analyses in normal and ZFP57 mutant mouse ES cells to understand the relative importance of ZFP57 at imprints, unique and repetitive regions of the genome.

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Epigenetics & chromatin, 12, 1756-8935, 49, 2019

PMID: 31399135

Open Access

Dosage compensation plans: protein aggregation provides additional insurance against aneuploidy.
Samant RS, Masto VB, Frydman J

Gene dosage alterations caused by aneuploidy are a common feature of most cancers yet pose severe proteotoxic challenges. Therefore, cells have evolved various dosage compensation mechanisms to limit the damage caused by the ensuing protein level imbalances. For instance, for heteromeric protein complexes, excess nonstoichiometric subunits are rapidly recognized and degraded. In this issue of , Brennan et al. (pp. 1031-1047) reveal that sequestration of nonstoichiometric subunits into aggregates is an alternative mechanism for dosage compensation in aneuploid budding yeast and human cell lines. Using a combination of proteomic and genetic techniques, they found that excess proteins undergo either degradation or aggregation but not both. Which route is preferred depends on the half-life of the protein in question. Given the multitude of diseases linked to either aneuploidy or protein aggregation, this study could serve as a springboard for future studies with broad-spanning implications.

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Genes & development, 33, 1549-5477, 1027-1030, 2019

PMID: 31371460

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.

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Developmental cell, , 1878-1551, , 2019

PMID: 31353311

Neuronal XBP-1 Activates Intestinal Lysosomes to Improve Proteostasis in C. elegans.
Imanikia S, Özbey NP, Krueger C, Casanueva MO, Taylor RC

The unfolded protein response of the endoplasmic reticulum (UPR) is a crucial mediator of secretory pathway homeostasis. Expression of the spliced and active form of the UPR transcription factor XBP-1, XBP-1s, in the nervous system triggers activation of the UPR in the intestine of Caenorhabditis elegans (C. elegans) through release of a secreted signal, leading to increased longevity. We find that expression of XBP-1s in the neurons or intestine of the worm strikingly improves proteostasis in multiple tissues, through increased clearance of toxic proteins. To identify the mechanisms behind this enhanced proteostasis, we conducted intestine-specific RNA-seq analysis to identify genes upregulated in the intestine when XBP-1s is expressed in neurons. This revealed that neuronal XBP-1s increases the expression of genes involved in lysosome function. Lysosomes in the intestine of animals expressing neuronal XBP-1s are more acidic, and lysosomal protease activity is higher. Moreover, intestinal lysosome function is necessary for enhanced lifespan and proteostasis. These findings suggest that activation of the UPR in the intestine through neuronal signaling can increase the activity of lysosomes, leading to extended longevity and improved proteostasis across tissues.

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Current biology : CB, 29, 1879-0445, 2322-2338.e7, 2019

PMID: 31303493

Open Access

The murine IgH locus contains a distinct DNA sequence motif for the chromatin regulatory factor CTCF.
Ciccone DN, Namiki Y, Chen C, Morshead KB, Wood AL, Johnston CM, Morris JW, Wang Y, Sadreyev R, Corcoran AE, Matthews AGW, Oettinger MA

Antigen receptor assembly in lymphocytes involves stringently regulated coordination of specific DNA rearrangement events across several large chromosomal domains. Previous studies indicate that transcription factors such as paired box 5 (PAX5), Yin Yang 1 (YY1), and CCCTC-binding factor (CTCF) play a role in regulating the accessibility of the antigen receptor loci to the V(D)J recombinase, which is required for these rearrangements. To gain clues about the role of CTCF binding at the murine immunoglobulin heavy chain (IgH) locus, we utilized a computational approach that identified 144 putative CTCF-binding sites within this locus. We found that these CTCF sites share a consensus motif distinct from other CTCF sites in the mouse genome. Additionally, we could divide these CTCF sites into three categories: intergenic sites remote from any coding element, upstream sites present within 8 kb of the VH-leader exon, and recombination signal sequence (RSS)-associated sites characteristically located at a fixed distance (~18 bp) downstream of the RSS. We noted that the intergenic and upstream sites are located in the distal portion of the VH locus, whereas the RSS-associated sites are located in the DH-proximal region. Computational analysis indicated that the prevalence of CTCF-binding sites at the IgH locus is evolutionarily conserved. In all species analyzed, these sites exhibit a striking strand-orientation bias, with > 98% of the murine sites being present in one orientation with respect to VH gene transcription. Electrophoretic mobility shift and enhancer-blocking assays and ChIP-chip analysis confirmed CTCF binding to these sites both in vitro and in vivo.

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The Journal of biological chemistry, , 1083-351X, , 2019

PMID: 31285261

RNA proximity sequencing reveals the spatial organization of the transcriptome in the nucleus.
Morf J, Wingett SW, Farabella I, Cairns J, Furlan-Magaril M, Jiménez-García LF, Liu X, Craig FF, Walker S, Segonds-Pichon A, Andrews S, Marti-Renom MA, Fraser P

The global, three-dimensional organization of RNA molecules in the nucleus is difficult to determine using existing methods. Here we introduce Proximity RNA-seq, which identifies colocalization preferences for pairs or groups of nascent and fully transcribed RNAs in the nucleus. Proximity RNA-seq is based on massive-throughput RNA barcoding of subnuclear particles in water-in-oil emulsion droplets, followed by cDNA sequencing. Our results show RNAs of varying tissue-specificity of expression, speed of RNA polymerase elongation and extent of alternative splicing positioned at varying distances from nucleoli. The simultaneous detection of multiple RNAs in proximity to each other distinguishes RNA-dense from sparse compartments. Application of Proximity RNA-seq will facilitate study of the spatial organization of transcripts in the nucleus, including non-coding RNAs, and its functional relevance.

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Nature biotechnology, 37, 1546-1696, 793-802, 2019

PMID: 31267103

Human pancreatic islet three-dimensional chromatin architecture provides insights into the genetics of type 2 diabetes.
Miguel-Escalada I, Bonàs-Guarch S, Cebola I, Ponsa-Cobas J, Mendieta-Esteban J, Atla G, Javierre BM, Rolando DMY, Farabella I, Morgan CC, García-Hurtado J, Beucher A, Morán I, Pasquali L, Ramos-Rodríguez M, Appel EVR, Linneberg A, Gjesing AP, Witte DR, Pedersen O, Grarup N, Ravassard P, Torrents D, Mercader JM, Piemonti L, Berney T, de Koning EJP, Kerr-Conte J, Pattou F, Fedko IO, Groop L, Prokopenko I, Hansen T, Marti-Renom MA, Fraser P, Ferrer J

Genetic studies promise to provide insight into the molecular mechanisms underlying type 2 diabetes (T2D). Variants associated with T2D are often located in tissue-specific enhancer clusters or super-enhancers. So far, such domains have been defined through clustering of enhancers in linear genome maps rather than in three-dimensional (3D) space. Furthermore, their target genes are often unknown. We have created promoter capture Hi-C maps in human pancreatic islets. This linked diabetes-associated enhancers to their target genes, often located hundreds of kilobases away. It also revealed >1,300 groups of islet enhancers, super-enhancers and active promoters that form 3D hubs, some of which show coordinated glucose-dependent activity. We demonstrate that genetic variation in hubs impacts insulin secretion heritability, and show that hub annotations can be used for polygenic scores that predict T2D risk driven by islet regulatory variants. Human islet 3D chromatin architecture, therefore, provides a framework for interpretation of T2D genome-wide association study (GWAS) signals.

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Nature genetics, 51, 1546-1718, 1137-1148, 2019

PMID: 31253982

Common and distinct transcriptional signatures of mammalian embryonic lethality.
Collins JE, White RJ, Staudt N, Sealy IM, Packham I, Wali N, Tudor C, Mazzeo C, Green A, Siragher E, Ryder E, White JK, Papatheodoru I, Tang A, Füllgrabe A, Billis K, Geyer SH, Weninger WJ, Galli A, Hemberger M, Stemple DL, Robertson E, Smith JC, Mohun T, Adams DJ, Busch-Nentwich EM

The Deciphering the Mechanisms of Developmental Disorders programme has analysed the morphological and molecular phenotypes of embryonic and perinatal lethal mouse mutant lines in order to investigate the causes of embryonic lethality. Here we show that individual whole-embryo RNA-seq of 73 mouse mutant lines (>1000 transcriptomes) identifies transcriptional events underlying embryonic lethality and associates previously uncharacterised genes with specific pathways and tissues. For example, our data suggest that Hmgxb3 is involved in DNA-damage repair and cell-cycle regulation. Further, we separate embryonic delay signatures from mutant line-specific transcriptional changes by developing a baseline mRNA expression catalogue of wild-type mice during early embryogenesis (4-36 somites). Analysis of transcription outside coding sequence identifies deregulation of repetitive elements in Morc2a mutants and a gene involved in gene-specific splicing. Collectively, this work provides a large scale resource to further our understanding of early embryonic developmental disorders.

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Nature communications, 10, 2041-1723, 2792, 2019

PMID: 31243271

Open Access

Identification of a novel orally bioavailable ERK5 inhibitor with selectivity over p38α and BRD4.
Myers SM, Miller DC, Molyneux L, Arasta M, Bawn RH, Blackburn TJ, Cook SJ, Edwards N, Endicott JA, Golding BT, Griffin RJ, Hammonds T, Hardcastle IR, Harnor SJ, Heptinstall AB, Lochhead PA, Martin MP, Martin NC, Newell DR, Owen PJ, Pang LC, Reuillon T, Rigoreau LJM, Thomas HD, Tucker JA, Wang LZ, Wong AC, Noble MEM, Wedge SR, Cano C

Extracellular regulated kinase 5 (ERK5) signalling has been implicated in driving a number of cellular phenotypes including endothelial cell angiogenesis and tumour cell motility. Novel ERK5 inhibitors were identified using high throughput screening, with a series of pyrrole-2-carboxamides substituted at the 4-position with an aroyl group being found to exhibit IC values in the micromolar range, but having no selectivity against p38α MAP kinase. Truncation of the N-substituent marginally enhanced potency (∼3-fold) against ERK5, but importantly attenuated inhibition of p38α. Systematic variation of the substituents on the aroyl group led to the selective inhibitor 4-(2-bromo-6-fluorobenzoyl)-N-(pyridin-3-yl)-1H-pyrrole-2-carboxamide (IC 0.82 μM for ERK5; IC > 120 μM for p38α). The crystal structure (PDB 5O7I) of this compound in complex with ERK5 has been solved. This compound was orally bioavailable and inhibited bFGF-driven Matrigel plug angiogenesis and tumour xenograft growth. The selective ERK5 inhibitor described herein provides a lead for further development into a tool compound for more extensive studies seeking to examine the role of ERK5 signalling in cancer and other diseases.

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European journal of medicinal chemistry, 178, 1768-3254, 530-543, 2019

PMID: 31212132

Vismodegib resistant mutations are not selected in multifocal relapses of locally advanced basal cell carcinoma after vismodegib discontinuation.
Ighilahriz M, Benfodda M, Sharpe H, Soufir N, Mourah S, Dumaz N, Battistella M, Savina A, Bouquet F, Nikolaev S, Basset-Seguin N

Hedgehog pathway inhibitors (HPI) inactivating SMO , have become first line treatment for patients with locally advanced BCC (laBCC). HPI safety and efficacy have been shown in clinical trials . Nevertheless, common adverse events lead to treatment discontinuation. This article is protected by copyright. All rights reserved.

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Journal of the European Academy of Dermatology and Venereology : JEADV, , 1468-3083, , 2019

PMID: 31187903

The adjuvant GLA-SE promotes human Tfh cell expansion and emergence of public TCRβ clonotypes.
Hill DL, Pierson W, Bolland DJ, Mkindi C, Carr EJ, Wang J, Houard S, Wingett SW, Audran R, Wallin EF, Jongo SA, Kamaka K, Zand M, Spertini F, Daubenberger C, Corcoran AE, Linterman MA

The generation of protective humoral immunity after vaccination relies on the productive interaction between antigen-specific B cells and T follicular helper (Tfh) cells. Despite the central role of Tfh cells in vaccine responses, there is currently no validated way to enhance their differentiation in humans. From paired human lymph node and blood samples, we identify a population of circulating Tfh cells that are transcriptionally and clonally similar to germinal center Tfh cells. In a clinical trial of vaccine formulations, circulating Tfh cells were expanded in Tanzanian volunteers when an experimental malaria vaccine was adjuvanted in GLA-SE but not when formulated in Alum. The GLA-SE-formulated peptide was associated with an increase in the extrafollicular antibody response, long-lived antibody production, and the emergence of public TCRβ clonotypes in circulating Tfh cells. We demonstrate that altering vaccine adjuvants is a rational approach for enhancing Tfh cells in humans, thereby supporting the long-lived humoral immunity that is required for effective vaccines.

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The Journal of experimental medicine, , 1540-9538, , 2019

PMID: 31175140

Alternative Translation Initiation Generates a Functionally Distinct Isoform of the Stress-Activated Protein Kinase MK2.
Trulley P, Snieckute G, Bekker-Jensen D, Menon MB, Freund R, Kotlyarov A, Olsen JV, Diaz-Muñoz MD, Turner M, Bekker-Jensen S, Gaestel M, Tiedje C

Alternative translation is an important mechanism of post-transcriptional gene regulation leading to the expression of different protein isoforms originating from the same mRNA. Here, we describe an abundant long isoform of the stress/p38-activated protein kinase MK2. This isoform is constitutively translated from an alternative CUG translation initiation start site located in the 5' UTR of its mRNA. The RNA helicase eIF4A1 is needed to ensure translation of the long and the known short isoforms of MK2, of which the molecular properties were determined. Only the short isoform phosphorylated Hsp27 in vivo, supported migration and stress-induced immediate early gene (IEG) expression. Interaction profiling revealed short-isoform-specific binding partners that were associated with migration. In contrast, the long isoform contains at least one additional phosphorylatable serine in its unique N terminus. In sum, our data reveal a longer isoform of MK2 with distinct physiological properties.

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Cell reports, 27, 2211-1247, 2859-2870.e6, 2019

PMID: 31167133

Open Access

Heterochronic faecal transplantation boosts gut germinal centres in aged mice.
Stebegg M, Silva-Cayetano A, Innocentin S, Jenkins TP, Cantacessi C, Gilbert C, Linterman MA

Ageing is a complex multifactorial process associated with a plethora of disorders, which contribute significantly to morbidity worldwide. One of the organs significantly affected by age is the gut. Age-dependent changes of the gut-associated microbiome have been linked to increased frailty and systemic inflammation. This change in microbial composition with age occurs in parallel with a decline in function of the gut immune system; however, it is not clear whether there is a causal link between the two. Here we report that the defective germinal centre reaction in Peyer's patches of aged mice can be rescued by faecal transfers from younger adults into aged mice and by immunisations with cholera toxin, without affecting germinal centre reactions in peripheral lymph nodes. This demonstrates that the poor germinal centre reaction in aged animals is not irreversible, and that it is possible to improve this response in older individuals by providing appropriate stimuli.

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Nature communications, 10, 2041-1723, 2443, 2019

PMID: 31164642

Establishment of porcine and human expanded potential stem cells.
Gao X, Nowak-Imialek M, Chen X, Chen D, Herrmann D, Ruan D, Chen ACH, Eckersley-Maslin MA, Ahmad S, Lee YL, Kobayashi T, Ryan D, Zhong J, Zhu J, Wu J, Lan G, Petkov S, Yang J, Antunes L, Campos LS, Fu B, Wang S, Yong Y, Wang X, Xue SG, Ge L, Liu Z, Huang Y, Nie T, Li P, Wu D, Pei D, Zhang Y, Lu L, Yang F, Kimber SJ, Reik W, Zou X, Shang Z, Lai L, Surani A, Tam PPL, Ahmed A, Yeung WSB, Teichmann SA, Niemann H, Liu P

We recently derived mouse expanded potential stem cells (EPSCs) from individual blastomeres by inhibiting the critical molecular pathways that predispose their differentiation. EPSCs had enriched molecular signatures of blastomeres and possessed developmental potency for all embryonic and extra-embryonic cell lineages. Here, we report the derivation of porcine EPSCs, which express key pluripotency genes, are genetically stable, permit genome editing, differentiate to derivatives of the three germ layers in chimeras and produce primordial germ cell-like cells in vitro. Under similar conditions, human embryonic stem cells and induced pluripotent stem cells can be converted, or somatic cells directly reprogrammed, to EPSCs that display the molecular and functional attributes reminiscent of porcine EPSCs. Importantly, trophoblast stem-cell-like cells can be generated from both human and porcine EPSCs. Our pathway-inhibition paradigm thus opens an avenue for generating mammalian pluripotent stem cells, and EPSCs present a unique cellular platform for translational research in biotechnology and regenerative medicine.

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Nature cell biology, 21, 1476-4679, 687-699, 2019

PMID: 31160711

Safe targeting of T cell acute lymphoblastic leukemia by pathology-specific NOTCH inhibition.
Habets RA, de Bock CE, Serneels L, Lodewijckx I, Verbeke D, Nittner D, Narlawar R, Demeyer S, Dooley J, Liston A, Taghon T, Cools J, de Strooper B

Given the high frequency of activating mutations in T cell acute lymphoblastic leukemia (T-ALL), inhibition of the γ-secretase complex remains an attractive target to prevent ligand-independent release of the cytoplasmic tail and oncogenic NOTCH1 signaling. However, four different γ-secretase complexes exist, and available inhibitors block all complexes equally. As a result, these cause severe "on-target" gastrointestinal tract, skin, and thymus toxicity, limiting their therapeutic application. Here, we demonstrate that genetic deletion or pharmacologic inhibition of the presenilin-1 (PSEN1) subclass of γ-secretase complexes is highly effective in decreasing leukemia while avoiding dose-limiting toxicities. Clinically, T-ALL samples were found to selectively express only PSEN1-containing γ-secretase complexes. The conditional knockout of in developing T cells attenuated the development of a mutant NOTCH1-driven leukemia in mice in vivo but did not abrogate normal T cell development. Treatment of T-ALL cell lines with the selective PSEN1 inhibitor MRK-560 effectively decreased mutant NOTCH1 processing and led to cell cycle arrest. These observations were extended to T-ALL patient-derived xenografts in vivo, demonstrating that MRK-560 treatment decreases leukemia burden and increased overall survival without any associated gut toxicity. Therefore, PSEN1-selective compounds provide a potential therapeutic strategy for safe and effective targeting of T-ALL and possibly also for other diseases in which NOTCH signaling plays a role.

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Science translational medicine, 11, 1946-6242, , 2019

PMID: 31142678

MicroRNA-155 is essential for the optimal proliferation and survival of plasmablast B cells.
Arbore G, Henley T, Biggins L, Andrews S, Vigorito E, Turner M, Leyland R

A fast antibody response can be critical to contain rapidly dividing pathogens. This can be achieved by the expansion of antigen-specific B cells in response to T-cell help followed by differentiation into plasmablasts. MicroRNA-155 (miR-155) is required for optimal T-cell-dependent extrafollicular responses via regulation of PU.1, although the cellular processes underlying this defect are largely unknown. Here, we show that miR-155 regulates the early expansion of B-blasts and later on the survival and proliferation of plasmablasts in a B-cell-intrinsic manner, by tracking antigen-specific B cells in vivo since the onset of antigen stimulation. In agreement, comparative analysis of the transcriptome of miR-155-sufficient and miR-155-deficient plasmablasts at the peak of the response showed that the main processes regulated by miR-155 were DNA metabolic process, DNA replication, and cell cycle. Thus, miR-155 controls the extent of the extrafollicular response by regulating the survival and proliferation of B-blasts, plasmablasts and, consequently, antibody production.

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Life science alliance, 2, 2575-1077, , 2019

PMID: 31097471

Open Access

Long-range enhancer-promoter contacts in gene expression control.
Schoenfelder S, Fraser P

Spatiotemporal gene expression programmes are orchestrated by transcriptional enhancers, which are key regulatory DNA elements that engage in physical contacts with their target-gene promoters, often bridging considerable genomic distances. Recent progress in genomics, genome editing and microscopy methodologies have enabled the genome-wide mapping of enhancer-promoter contacts and their functional dissection. In this Review, we discuss novel concepts on how enhancer-promoter interactions are established and maintained, how the 3D architecture of mammalian genomes both facilitates and constrains enhancer-promoter contacts, and the role they play in gene expression control during normal development and disease.

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Nature reviews. Genetics, , 1471-0064, , 2019

PMID: 31086298

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. identify ATG2, a member of the autophagy-related protein family, as a lipid transfer protein and provide important novel insights on how autophagosomes grow.

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

PMID: 31076453

Immunodeficiency, autoimmune thrombocytopenia and enterocolitis caused by autosomal recessive deficiency of PIK3CD-encoded phosphoinositide 3-kinase δ.
Swan DJ, Aschenbrenner D, Lamb CA, Chakraborty K, Clark J, Pandey S, Engelhardt KR, Chen R, Cavounidis A, Ding Y, Krasnogor N, Carey CD, Acres M, Needham S, Cant AJ, Arkwright PD, Chandra A, Okkenhaug K, Uhlig HH, Hambleton S

Haematologica, , 1592-8721, , 2019

PMID: 31073077

Open Access

MEK1/2 inhibitor withdrawal reverses acquired resistance driven by BRAF amplification whereas KRAS amplification promotes EMT-chemoresistance.
Sale MJ, Balmanno K, Saxena J, Ozono E, Wojdyla K, McIntyre RE, Gilley R, Woroniuk A, Howarth KD, Hughes G, Dry JR, Arends MJ, Caro P, Oxley D, Ashton S, Adams DJ, Saez-Rodriguez J, Smith PD, Cook SJ

Acquired resistance to MEK1/2 inhibitors (MEKi) arises through amplification of BRAF or KRAS to reinstate ERK1/2 signalling. Here we show that BRAF amplification and MEKi resistance are reversible following drug withdrawal. Cells with BRAF amplification are addicted to MEKi to maintain a precise level of ERK1/2 signalling that is optimal for cell proliferation and survival, and tumour growth in vivo. Robust ERK1/2 activation following MEKi withdrawal drives a p57-dependent G1 cell cycle arrest and senescence or expression of NOXA and cell death, selecting against those cells with amplified BRAF. p57 expression is required for loss of BRAF amplification and reversal of MEKi resistance. Thus, BRAF amplification confers a selective disadvantage during drug withdrawal, validating intermittent dosing to forestall resistance. In contrast, resistance driven by KRAS amplification is not reversible; rather ERK1/2 hyperactivation drives ZEB1-dependent epithelial-to-mesenchymal transition and chemoresistance, arguing strongly against the use of drug holidays in cases of KRAS amplification.

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Nature communications, 10, 2041-1723, 2030, 2019

PMID: 31048689

FcγRIIb differentially regulates pre-immune and germinal center B cell tolerance in mouse and human.
Espéli M, Bashford-Rogers R, Sowerby JM, Alouche N, Wong L, Denton AE, Linterman MA, Smith KGC

Several tolerance checkpoints exist throughout B cell development to control autoreactive B cells and prevent the generation of pathogenic autoantibodies. FcγRIIb is an Fc receptor that inhibits B cell activation and, if defective, is associated with autoimmune disease, yet its impact on specific B cell tolerance checkpoints is unknown. Here we show that reduced expression of FcγRIIb enhances the deletion and anergy of autoreactive immature B cells, but in contrast promotes autoreactive B cell expansion in the germinal center and serum autoantibody production, even in response to exogenous, non-self antigens. Our data thus show that FcγRIIb has opposing effects on pre-immune and post-immune tolerance checkpoints, and suggest that B cell tolerance requires the control of bystander germinal center B cells with low or no affinity for the immunizing antigen.

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Nature communications, 10, 2041-1723, 1970, 2019

PMID: 31036800