Project description:The mRNA cap recruits factors essential for transcript processing and translation initiation. We report that regulated mRNA cap methylation is a feature of embryonic stem cell (ESC) differentiation. Expression of the mRNA cap methyltransferase activating subunit, RAM, is elevated in ESCs resulting in high levels of mRNA cap methylation and expression of Oct4 and Sox2 and other pluripotency-associated factors. During neural differentiation, RAM is suppressed which is required for loss of Oct4 and Sox2 and correct expression of neural markers.
Project description:The mRNA cap recruits factors essential for transcript processing and translation initiation. We report that regulated mRNA cap methylation is a feature of embryonic stem cell (ESC) differentiation. Expression of the mRNA cap methyltransferase activating subunit, RAM, is elevated in ESCs resulting in high levels of mRNA cap methylation and expression of Oct4 and Sox2 and other pluripotency-associated factors. During neural differentiation, RAM is suppressed which is required for loss of Oct4 and Sox2 and correct expression of neural markers. Cells were treated with control or RAM siRNA and cytosolic RNA or polysome RNA (actively translated) was sequenced.
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.
