To Elucidate The Molecular Mechanisms Involved in Protein Arginine Methyltransferase 6-Mediated Promotion of Megakaryocytic Differentiation in K562 Cells
| Autor: | Lin-Li Liao, 廖琳立 |
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| Rok vydání: | 2014 |
| Druh dokumentu: | 學位論文 ; thesis |
| Popis: | 102 Hematopoiesis is a tightly regulated process responsible for the production of all kinds of mature blood cells. Megakaryocytes (MK) are generated from multipotent hematopoietic stem cells and mature to produce platelets. Megakaryopoiesis requires proper regulation by cytokines which stimulates proliferation and differentiation of MK progenitor cells. Several pathways including MAPK, PI3K and JAK/STAT are known to regulate this process. In mammals, protein arginine methylation is catalyzed by a sequence-related family of protein arginine methyltransferases (PRMTs) which are involved in a variety of important cellular functions. PRMT6 has been implicated in transcriptional regulation, DNA repair, and human immunodeficiency virus pathogenesis. However, the role of PRMT6 in MK differentiation remains elusive. Previous studies of this lab showed that overexpression of PRMT6 promoted MK differentiation induced by phorbol myristate acetate (PMA) in K562 cells. In this study, I investigated the molecular events involved in PRMT6-mediated promotion of MK differentiation. I constructed a methyl-transferase dead mutant PRMT6 KA which could no longer promote PMA-induced MK differentiation, suggesting that PRMT6 methylate specific substrates for its function. Previous studies of this lab showed that RhoGDIα promoted MK differentiation and methylation of Arg 111 and Arg 152 is required for this effect. I found that RhoGDIα is essential for PRMT6 to promote MK differentiation. RhoGDIα R111/152K mutant could not promote MK differentiation mediated by PRMT6 mediated MK differentiation and PRMT6 KA could not promote the stimulatory effect of RhoGDIα. When p38α was inhibited or deficient by shRNA, PRMT6 could not further promote MK differentiation. I also found PRMT6 inhibited p38 activation and reverted the suppression by p38 on MK differentiation. By using various pharmacological inhibitors, I found that inhibition of STAT3 and PI3K suppressed the stimulatory effect of PRMT6. We showed in our previous study that PRMT1 suppressed MK differentiation. Interestingly, when over-expressed together, PRMT6 overrode the effect of PRMT1 and promoted MK differentiation. I found it may be achieved by PRMT6 suppressing p38 activation mediated by PRMT1. |
| Databáze: | Networked Digital Library of Theses & Dissertations |
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