The Institute of Biomedical Sciences and School of Life Sciences, East China Normal University, Shanghai 200241.
Nucleic Acids Res. 2009 Nov;37(21):7059-71. doi: 10.1093/nar/gkp773.
SMYD1 is a heart and muscle specific SET-MYND domain containing protein, which functions as a histone methyltransferase and regulates downstream gene transcription. We demonstrated that the expression of SMYD1 is restricted in the heart and skeletal muscle tissues in human. To reveal the regulatory mechanisms of SMYD1 expression during myogenesis and cardiogenesis, we cloned and characterized the human SMYD1 promoter, which contains highly conserved serum response factor (SRF) and myogenin binding sites. Overexpression of SRF and myogenin significantly increased the endogenous expression level of Smyd1 in C2C12 cells, respectively. Deletion of Srf in the heart of mouse embryos dramatically decreased the expression level of Smyd1 mRNA and the expression of Smyd1 can be rescued by exogenous SRF introduction in SRF null ES cells during differentiation. Furthermore, we demonstrated that SRF binds to the CArG site and myogenin binds to the E-box element on Smyd1 promoter region using EMSA and ChIP assays. Moreover, forced expression of SMYD1 accelerates myoblast differentiation and myotube formation in C2C12 cells. Taken together, these studies demonstrated that SMYD1 is a key regulator of myogenic differentiation and acts as a downstream target of muscle regulatory factors, SRF and myogenin.
SMYD1 是一种心脏和肌肉特异性的 SET-MYND 结构域蛋白，具有组蛋白甲基转移酶的功能，可调节下游基因转录。我们发现 SMYD1 主要在人体的心脏和骨骼肌组织中表达。为了揭示 SMYD1 在心肌生成和心生成过程中的表达调控机制，我们克隆并鉴定了人 SMYD1 启动子，该启动子含有高度保守的血清反应因子（SRF）和肌生成素结合位点。SRF 和肌生成素的过表达分别显著增加了 C2C12 细胞中内源性 Smyd1 的表达水平。在小鼠胚胎心脏中敲除 Srf 可显著降低 Smyd1 mRNA 的表达水平，并且在 SRF 缺失的 ES 细胞分化过程中外源 SRF 的引入可挽救 Smyd1 的表达。此外，我们通过 EMSA 和 ChIP 实验证明，SRF 结合到 Smyd1 启动子区域的 CArG 位点，而肌生成素结合到 E-box 元件上。此外，SMYD1 的强制表达可加速 C2C12 细胞中的成肌细胞分化和肌管形成。综上所述，这些研究表明 SMYD1 是肌生成分化的关键调节因子，并且是肌肉调节因子 SRF 和肌生成素的下游靶标。
