EZH2介导GATA-4调控miR-29a在骨骼肌发育中的作用机制

骨骼肌的发育过程是复杂而有序的，但其调节机制，目前尚未阐明。我们发现， GATA-4不仅促进成肌细胞C2C12增殖和分化，还抑制miR-29a 的表达。由于GATA-4是转录激活因子，所以推测此过程应该有抑制因子参与。鉴于Polycomb 蛋白复合体能抑制基因表达，并且我们已经证明其关键成员EZH2与GATA-4形成蛋白复合体并结合在miR-29a的启动子区，因此，我们提出了“EZH2介导GATA-4抑制miR-29a表达并在骨骼肌发育中发挥作用” 的假说，并拟进行下列研究：首先，分析在骨骼肌发育中，EZH2与GATA-4在miR-29a启动子区是否结合、是否依赖于H3K27me3、是否归因于异染色质的发生；其次，分析上述过程是否有Polycomb蛋白复合体中PRC1不同组分的参与及对骨骼肌发育的影响。上述研究将进一步阐明骨骼肌发育的分子机理，同时也为防治先天性骨骼肌发育不良提供理论依据。

Skeletal muscle development is a complex process which occurred in an orderly way, but the exact mechanism by which skeletal muscle development is regulated has not been fully elucidated. We found that GATA-4 not only promoted the proliferation and differentiation of C2C12 myoblasts, but also inhibited the expression of miR-29a. Since GATA-4 functions as a transcriptional activator, we speculate that transcription repressors should be involved in this process. Given the Polycomb group proteins are able to mediate gene silencing through the modification of chromatin structure, furthermore, EZH2, a member of the Polycomb protein family, can form protein complexes with GATA-4 and binds to the promoter of miR-29a, we propose the hypothesis that EZH2 play roles in the expression of miR-29a inhibited by GATA-4 during skeletal muscle development. To address the hypothesis, we will first analyze whether EZH2 and GATA-4 bind to the miR-29a promoter, and whether the binding of EZH2 and GATA-4 to the miR-29a promoter is depended on H3K27me3, or can be attributed to heterochromatin during skeletal muscle development. Next, we will analyze which member of Polycomb repressive complex 1 (PRC1) is involved in the above mentioned process, and exerts its effects on skeletal muscle development. These complementary lines of investigation will provide insight to understand the regulatory mechanisms of skeletal muscle development, which could provide more clues for prevention and treatment of congenital dysplasia of skeletal muscle.