Project description:The transcription factor Zic3 is required for maintenance of embryonic stem (ES) cell pluripotency (Lim LS et al, Mol Biol Cell. 2007;18:1348-1358). By genome-wide chromatin immunoprecipitation (ChIP-chip) in ES cells, we have identified 379 direct Zic3 targets, many of which are functionally associated with pluripotency, cell cycle, proliferation, oncogenesis and early embryogenesis.
Project description:Sustained expression of the key pluripotency transcriptional regulators and proliferative factors is needed for the maintenance of embryonic stem cells and early progenitors of various lineages. Zic3 is one of those factors which has been shown to be important for embryonic stem cell pluripotency. Through combinatorial analysis of transcription factor binding sites and the corresponding gene-regulation, we show that Zic3 not only activates key pluripotency genes but also acts cooperatively with them in connecting important circuits of regulation in ES cell in proliferation and maintenance of early progenitors.
Project description:The role of mitochondria dynamics and its molecular regulators remains largely unknown during naïve-to-primed pluripotent cell interconversion. Here we report that mitochondrial MTCH2 is a regulator of mitochondrial fusion, essential for the naïve-to-primed interconversion of murine embryonic stem cells (ESCs). During this interconversion, wild-type ESCs elongate their mitochondria and slightly alter their glutamine utilization. In contrast, MTCH2-/- ESCs fail to elongate their mitochondria and to alter their metabolism, maintaining high levels of histone acetylation and expression of naïve pluripotency markers. Importantly, enforced mitochondria elongation by the pro-fusion protein Mitofusin (MFN) 2 or by a dominant negative form of the pro-fission protein dynamin-related protein (DRP) 1 is sufficient to drive the exit from naïve pluripotency of both MTCH2-/- and wild-type ESCs. Taken together, our data indicate that mitochondria elongation, governed by MTCH2, plays a critical role and constitutes an early driving force in the naïve-to-primed pluripotency interconversion of murine ESCs.
Project description:Cellular binary fate decisions require the progeny to silence genes associated with the alternative fate. The major subsets of alpha:beta T cells have been extensively studied as a model system for fate decisions. While the transcription factor RUNX3 is required for the initiation of Cd4 silencing in CD8 T cell progenitors, it is not required to maintain the silencing of Cd4 and other helper T lineage genes. The other runt domain containing protein, RUNX1, silences Cd4 in an earlier T cell progenitor, but this silencing is reversed whereas the gene silencing after RUNX3 expression is not reverse. Therefore, we hypothesized that RUNX3 and not RUNX1 recruits other factors that maintains the silencing of helper T lineage genes in CD8 T cells. To this end, we performed a proteomics screen of RUNX1 and RUNX3 to determine candidate silencing factors.
