Project description:Genome-wide DNA methylation maps of mouse embryonic fibroblasts and reprogramming cells modulated by cell cycle and Dnmt1 expression
Project description:MBD-affinity purification (MAP) was employed to investigate the DNA methylation status at promoters of mouse embryonic fibroblasts (MEFs), both wild type and Lsh knock-out cells.<br>MAP is conceptually identical to ChIP, using an affinity column rather than an antibody.
Project description:PGCs undergo two distinct stages of demethylation before reaching a hypomethylated ground state at E13.5. Stage 1 occurs between E7.25- E9.5 in which PGCs experience a global loss of cytosine methylation. However, discreet loci escape this global loss of methylation and between E10.5-E13.5, stage 2 of demethylation takes place. In this stage these loci are targeted by Tet1 and Tet2 leading to the loss of the remaining methylation and resulting in the epigenetic ground state. Our data shows that Dnmt1 is responsible for maintaining the methylation of loci that escape stage 1 demethylation, and that it functions in a UHRF1 independent manner. Our data further demonstrates that when these loci lose methylation prior to stage 2 it results in early activation of the meiotic program, which leads to precocious differentiation of the germ line resulting in a decreased pool of PGCs in the embryo and subsequent infertility in adult mice.
Project description:The E3 ligase UHRF1 is an essential epigenetic cofactor for DNMT1 dependent maintenance DNA methylation, which provides a binding platform for DNMT1 by both cooperative binding of histones and hemi-methylated DNA as well as by ubiquitinating histone H3. Here, we conduct a comprehensive screen to identify novel ubiquitination targets of UHRF1 and its paralogue UHRF2 by comparing the ubiquitome of wildtype (wt), UHRF1- and UHRF2-deficient mouse embryonic stem cells. With an antibody-dependent enrichment of ubiquitin remnant motif-containing peptides followed by isobaric-labeling based quantitative mass spectrometry, we find both known and novel E3 ligase substrates of UHRF1 involved in a variety of biological processes such as RNA processing, DNA methylation and DNA damage repair.