Keeping egg cells fresh with epigenetics

January 1, 2018, Babraham Institute
DNA inside cells shown in blue, epigenetic methylation in green and another epigenetic marker called acetylation shown in red. Credit: Courtney Hanna, Babraham Institute

Keeping egg cells in stasis during childhood is a key part of female fertility. New research published today in Nature Structural and Molecular Biology sheds some light on the role of epigenetics in placing egg cells into stasis. A team led by Dr Gavin Kelsey in the Babraham Institute and colleagues in Dresden and Munich studied a protein called MLL2 and discovered how it produces a distinctive pattern of epigenetic marks that are needed for egg cell stasis.

A fertilised egg cell is the start of every human life. Yet, are created inside a woman's body before she is born. The are then kept in stasis throughout childhood until they're needed as an adult. If egg cells don't go into stasis they can't become mature eggs and they will never have the chance to form a new life. Putting an egg cell into stasis involves adding many epigenetic marks throughout its DNA.Epigenetic marks attached to DNA act as footnotes, indicating which genes are turned 'on' or 'off'. The scientists wanted to understand where these marks come from in egg cells and how mistakes can cause disease. It is particularly challenging to study in egg cells as there are so few of them. The team had to create new, highly sensitive ways to detect in such small numbers of cells.

Using this approach, they found that, as eggs develop, a mark called H3K4me3 spreads throughout the genome. Scientists have already seen the same mark close to the start of active genes in many cells, but the team discovered that its role in egg cells is different. They showed that the MLL2 protein is responsible for this unusual placement of H3K4me3 in egg cells. Without MLL2, most H3K4me3 marks in egg cells are lost and the cells die before getting the chance to form a new life.

Speaking about the results, first author Dr Courtney Hanna, said: "Our findings show that H3K4me3 is created in two ways. MLL2 can add the H3K4me3 mark without any nearby gene activity while another process, that doesn't use MLL2, places the same mark around . By studying this new mechanism we hope to expand our knowledge of epigenetics in general as well as adding to our understanding of fertility."Lead scientist, Dr Kelsey, said: "We are only beginning to unravel the details of the connection between epigenetics and , a fundamental aspect of biology that may play a part in transmitting information from mother to fetus. Discoveries like this highlight some of the unusual biological processes that take place in these highly important ."

DNA inside cells shown in blue. Epigenetic methylation marks shown in green. Credit: Courtney Hanna, Babraham Institute

Explore further: Breakthrough genomics technique can be used to map epigenetic marks across the genome using fewer cells

More information: Courtney W. Hanna et al, MLL2 conveys transcription-independent H3K4 trimethylation in oocytes, Nature Structural & Molecular Biology (2017). DOI: 10.1038/s41594-017-0013-5

Related Stories

Breakthrough genomics technique can be used to map epigenetic marks across the genome using fewer cells

September 20, 2016
A Ludwig Cancer Research study published online September 14th in Nature reports a novel technique to map specific chemical (or "epigenetic") modifications made to the protein packaging of DNA using a small population of ...

Rules governing expression of developmental genes in mouse embryonic stem cells are more nuanced than anticipated

August 11, 2013
A decade ago, gene expression seemed so straightforward: genes were either switched on or off. Not both. Then in 2006, a blockbuster finding reported that developmentally regulated genes in mouse embryonic stem cells can ...

New technique maps life's effects on our DNA

July 20, 2014
Researchers at the BBSRC-funded Babraham Institute, in collaboration with the Wellcome Trust Sanger Institute Single Cell Genomics Centre, have developed a powerful new single-cell technique to help investigate how the environment ...

Preventing a genetic uprising in early life

November 2, 2017
Molecules called endosiRNAs help us avoid genetic chaos, according to a new study from a team at the Babraham Institute. Much of the human genome contains pieces of DNA called transposons, a form of genetic parasite. When ...

Human embryonic stem cells remain embryonic because of epigenetic factors

October 4, 2007
A human embryonic stem cell is reined in – prevented from giving up its unique characteristics of self-renewal and pluripotency – by the presence of a protein modification that stifles any genes that would prematurely ...

Important mechanism of epigenetic gene regulation identified

October 30, 2017
How can defective gene activity leading to cancerbe avoided? Researchers at the University of Zurich have now identified a mechanism by which cells pass on the regulation of genetic information through epigenetic modifications. ...

Recommended for you

Student develops microfluidics device to help scientists identify early genetic markers of cancer

October 16, 2018
As anyone who has played "Where's Waldo" knows, searching for a single item in a landscape filled with a mélange of characters and objects can be a challenge. Chrissy O'Keefe, a Ph.D. student in the Department of Biomedical ...

Researchers use brain cells in a dish to study genetic origins of schizophrenia

October 16, 2018
A study in Biological Psychiatry has established a new analytical method for investigating the complex genetic origins of mental illnesses using brain cells that are grown in a dish from human embryonic stem cells. Researchers ...

Why heart contractions are weaker in those with hypertrophic cardiomyopathy

October 16, 2018
When a young athlete suddenly dies of a heart attack, chances are high that they suffer from familial hypertrophic cardiomyopathy (HCM). Itis the most common genetic heart disease in the US and affects an estimated 1 in 500 ...

Importance of cell cycle and cellular senescence in the placenta discovered

October 15, 2018
Working with researchers from Stanford University and St. Anna Children's Cancer Research, researchers from Jürgen Pollheimer's laboratory at the Medical University of Vienna's Department of Obstetrics and Gynecology have ...

Team's study reveals hidden lives of medical biomarkers

October 12, 2018
What do medical biomarkers do on evenings and weekends, when they might be considered off the clock?

Researchers find a 'critical need' for whole genome sequencing of young cancer patients

October 12, 2018
St. Jude Children's Research Hospital has re-defined the gold standard for diagnostic testing of childhood cancer patients in the precision-medicine era and has implemented the testing for new cancer patients. The findings ...

0 comments

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.