Project description:Changes in histone post-translational modifications are associated with aging through poorly defined mechanisms. Histone 3 lysine 4 (H3K4) methylation at promoters is deposited by SET1 family methyltransferases acting within conserved multiprotein complexes known as COMPASS. Using co-immunopurification coupled to mass spectrometry-based proteomics, we characterized complex members and binding partners in various genetic contexts, using WDR-5 or CFP-1 proteins as baits.
Project description:Epigenetic mechanisms including histone modifications have emerged as important factors influencing cell fate determination. The functional role of H3K4 methylation, however, remains largely unclear in the maintenance and differentiation of hematopoietic stem/progenitor cells (HSC/HPCs). Here we show that DPY30, a shared core subunit of the SET1/MLL family methyltransferase complexes and a facilitator of their H3K4 methylation activity, is important for ex vivo proliferation and differentiation of human CD34+ HPCs. DPY30 promotes HPC proliferation by directly regulating the expression of genes critical for cell proliferation. Interestingly, while DPY30 knockdown (KD) in HPCs impaired their differentiation into the myelomonocytic lineage, it potently promoted hemoglobin production and affected the kinetics of their differentiation into the erythroid lineage. In an in vivo model, we show that morpholino-mediated dpy30 KD resulted in severe defects in the development of the zebrafish hematopoietic system, which could be partially rescued by co-injection of dpy30 mRNA. Taken together, our results establish a critical role of DPY30 in the proliferation and appropriate differentiation of hematopoietic progenitor cells as well as in animal hematopoiesis. Finally, we also demonstrate a crucial role of DPY30 in the growth of several MLL1-fusion-mediated leukemia cell lines. Total RNAs from control (scr) or knockdown (hD2, hD5) cells before and after culturing under condition promoting myelomonocytic differentiation were subjected to Illumina microarray analyses.
Project description:It remains largely unclear if efficient H3K4 methylation, an epigenetic modification associated with gene activation, regulates fate determination of the postnatal neural stem cells (NSCs). By inactivating the Dpy30 subunit of the major mammalian H3K4 methyltransferase complexes in specific regions of mouse brain, we demonstrate a crucial role of efficient H3K4 methylation in maintaining both the self-renewal and differentiation capacity of postnatal NSCs. Loss Dpy30 disrupts the development of dentate gyrus and subventricular zone, the major regions for postnatal NSC activities. Dpy30 is indispensable for sustaining the self-renewal of NSCs in a cell-intrinsic manner. Dpy30 also enables the differentiation of mouse and human neural progenitor cells to neuronal and glial lineages. Dpy30 directly regulates H3K4 methylation and the induction of several genes critical in neurogenesis. These findings link a prominent epigenetic mechanism of gene expression to the fundamental properties of NSCs, and may have implications in neurodevelopmental disorders.