| Summary: | 碩士 === 國立陽明大學 === 生理學研究所 === 105 === Hematopoiesis is a dynamic and complex cellular event. Recent studies have shown that the landscape of DNA methylation is dynamically changed during hematopoiesis. DNA methylation, catalyzed by DNA methyltransferases (DNMTs), is the covalent addition of methyl group at the 5-carbon of the cytosine ring. There are three active enzymes, including DNMT1, DNMT3A and DNMT3B. The importance of DNMT3A in both hematopoietic stem and leukemic cell biology has been demonstrated. While, how DNMT3A modulates hematopoiesis is largely unclear. Our unpublished data indicated that loss of Dnmt3a in murine hematopoietic systems caused anemia. Thus, we are interested in the role and regulation of DNMT3A in erythropoiesis. The expression of DNMT3A was increased during erythrocytic differentiation of K562 and HEL cells. Knockdown and overexpression approaches demonstrated that DNMT3A modulated erythrocytic differentiation. Recent report demonstrates that the protein kinase phosphorylates DNMT3A to regulate its activity. Here, we found DNMT3A proteins were phosphorylated on serine residues during erythropoiesis. Further studies demonstrated that induction of erythrocytic differentiation promoted the association of cytosolic DNMT3A, ERK1/2 and AKT. Thus, we generated numerous DNMT3A mutations, according to a recent report, to study whether ERK1/2-mediated interaction and phosphorylation of DNMT3A modulated erythropoiesis. Our results demonstrated that binding to ERK1/2 and ERK1/2-mediated phosphorylation of DNMT3A can alter erythrocytic differentiation. In addition, our bioinformatic analysis found a patient-derived DNMT3A mutation, which localizes on potential ERK1/2 and AKT phosphorylation sequence. Further studies demonstrated that this site can affect differentiation. Taken together, we demonstrated the DNMT3A can modulate erythrocytic differentiation through ERK1/2-mediated phosphorylation.
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