Life Sciences Research for Lifelong Health

Gavin Kelsey

Research Summary

It is thought that epigenetic information can be programmed by environmental factors, such as diet and early life experiences, and such changes can be perpetuated long after these exposures and potentially to future generations.  Such epigenetic programming may contribute to our risk of developing disease in later life.  Imprinted genes (whose expression is determined by the parent that contributed them) are a model for how epigenetic events in gametes of one generation dictate gene activity in the next.

Our mapping of methylation of DNA in the egg, sperm and embryo suggests that this epigenetic influence may extend well beyond the small number of known imprinted genes.  Using genome-wide approaches, we are tracking the fate of DNA methylation patterns inherited from the egg and sperm, the stability of these marks throughout the lifetime and ageing, and how they affect activity of associated genes.  In particular, we are investigating whether DNA methylation in particular populations of neurons in the hypothalamus, the part of the brain that senses nutritional status to control metabolism and appetite, is altered by exposure to altered diets and may modify response to nutritional status.

The discovery that gene transcription is essential for DNA methylation and imprint establishment may help to explain how the methylation modifications in the genome of the egg may be modified by adverse environments or how imprinting is disrupted in some imprinted gene disorders.

Latest Publication:
Hira is essential for normal transcriptional regulation and efficient de novo DNA methylation during mouse oogenesis.
Nashun B, Hill PWS, Smallwood SA, Dharmalingam G, Amouroux R, Clark SJ, Sharma V, Ndjetehe E, Pelczar P, Festenstein R‎, Kelsey G, Hajkova P.
Mol Cell. 2015 AOP 5th Nov. 2015, doi:10.1016/j.molcel.2015.10.010.

Latest Publications

Genome-wide base-resolution mapping of DNA methylation in single cells using single-cell bisulfite sequencing (scBS-seq).
Clark SJ, Smallwood SA, Lee HJ, Krueger F, Reik W, Kelsey G

DNA methylation (DNAme) is an important epigenetic mark in diverse species. Our current understanding of DNAme is based on measurements from bulk cell samples, which obscures intercellular differences and prevents analyses of rare cell types. Thus, the ability to measure DNAme in single cells has the potential to make important contributions to the understanding of several key biological processes, such as embryonic development, disease progression and aging. We have recently reported a method for generating genome-wide DNAme maps from single cells, using single-cell bisulfite sequencing (scBS-seq), allowing the quantitative measurement of DNAme at up to 50% of CpG dinucleotides throughout the mouse genome. Here we present a detailed protocol for scBS-seq that includes our most recent developments to optimize recovery of CpGs, mapping efficiency and success rate; reduce hands-on time; and increase sample throughput with the option of using an automated liquid handler. We provide step-by-step instructions for each stage of the method, comprising cell lysis and bisulfite (BS) conversion, preamplification and adaptor tagging, library amplification, sequencing and, lastly, alignment and methylation calling. An individual with relevant molecular biology expertise can complete library preparation within 3 d. Subsequent computational steps require 1-3 d for someone with bioinformatics expertise.

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Nature protocols, 12, 1750-2799, 534-547, 2017

PMID: 28182018

DNA methylation and gene expression changes derived from assisted reproductive technologies can be decreased by reproductive fluids.
Canovas S, Ivanova E, Romar R, García-Martínez S, Soriano-Úbeda C, García-Vázquez FA, Saadeh H, Andrews S, Kelsey G, Coy P

The number of children born since the origin of Assisted Reproductive Technologies (ART) exceeds 5 million. The majority seem healthy, but a higher frequency of defects has been reported among ART-conceived infants, suggesting an epigenetic cost. We report the first whole-genome DNA methylation datasets from single pig blastocysts showing differences between in vivo and in vitro produced embryos. Blastocysts were produced in vitro either without (C-IVF) or in the presence of natural reproductive fluids (Natur-IVF). Natur-IVF embryos were of higher quality than C-IVF in terms of cell number and hatching ability to. RNA-Seq and DNA methylation analyses showed that Natur-IVF embryos have expression and methylation patterns closer to in vivo blastocysts. Genes involved in reprogramming, imprinting and development were affected by culture, with fewer aberrations in Natur-IVF embryos. Methylation analysis detected methylated changes in C-IVF, but not in Natur-IVF, at genes whose methylation could be critical, such as IGF2R and NNAT.

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eLife, 6, 2050-084X, , 2017

PMID: 28134613

Establishment and functions of DNA methylation in the germline.
Stewart KR, Veselovska L, Kelsey G

Epigenetic modifications established during gametogenesis regulate transcription and other nuclear processes in gametes, but also have influences in the zygote, embryo and postnatal life. This is best understood for DNA methylation which, established at discrete regions of the oocyte and sperm genomes, governs genomic imprinting. In this review, we describe how imprinting has informed our understanding of de novo DNA methylation mechanisms, highlight how recent genome-wide profiling studies have provided unprecedented insights into establishment of the sperm and oocyte methylomes and consider the fate and function of gametic methylation and other epigenetic modifications after fertilization.

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Epigenomics, , 1750-192X, , 2016

PMID: 27659720

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Latest Publications

Establishment and functions of DNA methylation in the germline.

Stewart KR, Veselovska L, Kelsey G

Epigenomics
1750-192X: (2016)

PMID: 27659720

Single-cell epigenomics: powerful new methods for understanding gene regulation and cell identity.

Clark SJ, Lee HJ, Smallwood SA

Genome biology
17 1474-760X:72 (2016)

PMID: 27091476

Pervasive polymorphic imprinted methylation in the human placenta.

Hanna CW, Peñaherrera MS, Saadeh H

Genome research
1549-5469: (2016)

PMID: 26769960

Parallel single-cell sequencing links transcriptional and epigenetic heterogeneity.

Angermueller C, Clark SJ, Lee HJ

Nature methods
1548-7105: (2016)

PMID: 26752769

Dynamic changes in histone modifications precede de novo DNA methylation in oocytes.

Stewart KR, Veselovska L, Kim J

Genes & development
1549-5477: (2015)

PMID: 26584620

Keeping methylation at bay.

Kelsey G

Nature genetics
47 1546-1718:427-8 (2015)

PMID: 25916897

Epigenetics: Cellular memory erased in human embryos.

Reik W,Kelsey G

Nature
511 1476-4687:540-1 (2014)

PMID: 25079550