Kelsey Group

Kelsey Group
Kelsey Group
Gavin Kelsey
Head of Programme
Kelsey Group

Research Summary

As well as genetic information, the egg and sperm also contribute epigenetic annotations that may influence gene activity after fertilisation. These annotations may be direct modifications of the DNA bases or of the proteins around which the DNA is wrapped into chromatin. Our goal is to understand whether, through epigenetics, factors such as a mother’s age or diet have consequences on the health of a child.
 
We examine how epigenetic states are set up in oocytes – or egg cells – and influence gene expression in the embryo. For example, repressive chromatin marks in oocytes lead to long-term silencing of genes inherited from the mother, particularly in cells that will form the placenta. We are also interested in how variations in DNA methylation come about in oocytes and whether we can use this variation as a marker for oocyte quality and embryo potential. To investigate these questions, we develop methods to profile epigenetic information in very small numbers of cells or even in single cells.

Latest Publications

Giaccari C, Cecere F, Argenziano L, Pagano A, Galvao A, Acampora D, Rossi G, Hay Mele B, Acurzio B, Coonrod S, Cubellis MV, Cerrato F, Andrews S, Cecconi S, Kelsey G, Riccio A Epigenetics

Maternal inactivation of genes encoding components of the subcortical maternal complex (SCMC) and its associated member, PADI6, generally results in early embryo lethality. In humans, SCMC gene variants were found in the healthy mothers of children affected by multilocus imprinting disturbances (MLID). However, how the SCMC controls the DNA methylation required to regulate imprinting remains poorly defined. We generated a mouse line carrying a missense variant that was identified in a family with Beckwith-Wiedemann syndrome and MLID. If homozygous in female mice, this variant resulted in interruption of embryo development at the two-cell stage. Single-cell multiomic analyses demonstrated defective maturation of mutant oocytes and incomplete DNA demethylation, down-regulation of zygotic genome activation (ZGA) genes, up-regulation of maternal decay genes, and developmental delay in two-cell embryos developing from mutant oocytes but little effect on genomic imprinting. Western blotting and immunofluorescence analyses showed reduced levels of UHRF1 in oocytes and abnormal localization of DNMT1 and UHRF1 in both oocytes and zygotes. Treatment with 5-azacytidine reverted DNA hypermethylation but did not rescue the developmental arrest of mutant embryos. Taken together, this study demonstrates that PADI6 controls both nuclear and cytoplasmic oocyte processes that are necessary for preimplantation epigenetic reprogramming and ZGA.

+view abstract Genes & development, PMID: 38453481 07 Mar 2024

Hernandez Mora JR, Buhigas C, Clark S, Del Gallego Bonilla R, Daskeviciute D, Monteagudo-Sánchez A, Poo-Llanillo ME, Medrano JV, Simón C, Meseguer M, Kelsey G, Monk D Epigenetics

During pre-implantation stages of mammalian development, maternally stored material promotes both the erasure of the sperm and oocyte epigenetic profiles and is responsible for concomitant genome activation. Here, we have utilized single-cell methylome and transcriptome sequencing (scM&T-seq) to quantify both mRNA expression and DNA methylation in oocytes and a developmental series of human embryos at single-cell resolution. We fully characterize embryonic genome activation and maternal transcript degradation and map key epigenetic reprogramming events in developmentally high-quality embryos. By comparing these signatures with early embryos that have undergone spontaneous cleavage-stage arrest, as determined by time-lapse imaging, we identify embryos that fail to appropriately activate their genomes or undergo epigenetic reprogramming. Our results indicate that a failure to successfully accomplish these essential milestones impedes the developmental potential of pre-implantation embryos and is likely to have important implications, similar to aneuploidy, for the success of assisted reproductive cycles.

+view abstract Cell reports, PMID: 36763500 09 Feb 2023

Demond H, Hanna CW, Castillo-Fernandez J, Santos F, Papachristou EK, Segonds-Pichon A, Kishore K, Andrews S, D'Santos CS, Kelsey G Epigenetics, Bioinformatics

EHMT1 (also known as GLP) is a multifunctional protein, best known for its role as an H3K9me1 and H3K9me2 methyltransferase through its reportedly obligatory dimerization with EHMT2 (also known as G9A). Here, we investigated the role of EHMT1 in the oocyte in comparison to EHMT2 using oocyte-specific conditional knockout mouse models ( cKO, cKO, cDKO), with ablation from the early phase of oocyte growth. Loss of EHMT1 in cKO and cDKO oocytes recapitulated meiotic defects observed in the cKO; however, there was a significant impairment in oocyte maturation and developmental competence in cKO and cDKO oocytes beyond that observed in the cKO. Consequently, loss of EHMT1 in oogenesis results, upon fertilization, in mid-gestation embryonic lethality. To identify H3K9 methylation and other meaningful biological changes in each mutant to explore the molecular functions of EHMT1 and EHMT2, we performed immunofluorescence imaging, multi-omics sequencing, and mass spectrometry (MS)-based proteome analyses in cKO oocytes. Although H3K9me1 was depleted only upon loss of EHMT1, H3K9me2 was decreased, and H3K9me2-enriched domains were eliminated equally upon loss of EHMT1 or EHMT2. Furthermore, there were more significant changes in the transcriptome, DNA methylome, and proteome in cDKO than cKO oocytes, with transcriptional derepression leading to increased protein abundance and local changes in genic DNA methylation in cDKO oocytes. Together, our findings suggest that EHMT1 contributes to local transcriptional repression in the oocyte, partially independent of EHMT2, and is critical for oogenesis and oocyte developmental competence.

+view abstract Genome research, PMID: 36690445 23 Jan 2023

Group Members

Gavin Kelsey

Head of Programme

Christian Belton

Postdoc Research Scientist

Amy Briffa

Postdoc Research Scientist

Antonio Galvao

Visiting Scientist

Irene Hernando Herraez

Visiting Scientist

Teruhito Ishihara

Postdoc Research Scientist

Elena Ivanova

Postdoc Research Scientist

Carmen Jones

PhD Student

Soumen Khan

Postdoc Research Scientist

Gavin Li

Research Assistant

Tomasz Malcom

Visiting Student

Leah McHugh

PhD Student

Alexandra Pokhilko

Postdoc Research Scientist

Connor Roberts

Research Assistant

Jasmin Stowers

Visiting Scientist

Karolina Wasilewska

Visiting Student