Department of Pharmacology, Chonnam National University Medical School, Jeollanamdo, Republic of Korea.
Basic Research Laboratory for Cardiac Remodeling, Chonnam National University Medical School, Jeollanamdo, Republic of Korea.
Exp Mol Med. 2018 Jan 12;50(1):e427. doi: 10.1038/emm.2017.236.
Sumoylation, the conjugation of a small ubiquitin-like modifier (SUMO) protein to a target, has diverse cellular effects. However, the functional roles of the SUMO modification during myogenesis have not been fully elucidated. Here, we report that basal sumoylation of histone deacetylase 1 (HDAC1) enhances the deacetylation of MyoD in undifferentiated myoblasts, whereas further sumoylation of HDAC1 contributes to switching its binding partners from MyoD to Rb to induce myocyte differentiation. Differentiation in C2C12 skeletal myoblasts induced new immunoblot bands above HDAC1 that were gradually enhanced during differentiation. Using SUMO inhibitors and sumoylation assays, we showed that the upper band was caused by sumoylation of HDAC1 during differentiation. Basal deacetylase activity was not altered in the SUMO modification-resistant mutant HDAC1 K444/476R (HDAC1 2R). Either differentiation or transfection of SUMO1 increased HDAC1 activity that was attenuated in HDAC1 2R. Furthermore, HDAC1 2R failed to deacetylate MyoD. Binding of HDAC1 to MyoD was attenuated by K444/476R. Binding of HDAC1 to MyoD was gradually reduced after 2 days of differentiation. Transfection of SUMO1 induced dissociation of HDAC1 from MyoD but potentiated its binding to Rb. SUMO1 transfection further attenuated HDAC1-induced inhibition of muscle creatine kinase luciferase activity that was reversed in HDAC1 2R. HDAC1 2R failed to inhibit myogenesis and muscle gene expression. In conclusion, HDAC1 sumoylation plays a dual role in MyoD signaling: enhancement of HDAC1 deacetylation of MyoD in the basally sumoylated state of undifferentiated myoblasts and dissociation of HDAC1 from MyoD during myogenesis.
SUMO 化，即小泛素样修饰蛋白（SUMO）与靶蛋白的连接，具有多种细胞效应。然而，SUMO 修饰在成肌过程中的功能作用尚未完全阐明。在这里，我们报告组蛋白去乙酰化酶 1（HDAC1）的基础 SUMO 化增强了未分化的成肌细胞中 MyoD 的去乙酰化作用，而 HDAC1 的进一步 SUMO 化有助于将其结合伙伴从 MyoD 切换到 Rb，从而诱导肌细胞分化。C2C12 骨骼肌成肌细胞的分化诱导出 HDAC1 上方的新免疫印迹带，这些带在分化过程中逐渐增强。使用 SUMO 抑制剂和 SUMO 化测定，我们表明，在分化过程中，HDAC1 的 SUMO 化导致了上带的产生。在 SUMO 修饰抗性突变体 HDAC1 K444/476R（HDAC1 2R）中，基础去乙酰化酶活性没有改变。分化或 SUMO1 的转染均增加了 HDAC1 活性，而在 HDAC1 2R 中则减弱了。此外，HDAC1 2R 无法使 MyoD 去乙酰化。HDAC1 与 MyoD 的结合因 K444/476R 而减弱。在分化的第 2 天，HDAC1 与 MyoD 的结合逐渐减少。SUMO1 的转染诱导 HDAC1 与 MyoD 的解离，但增强了其与 Rb 的结合。SUMO1 的转染进一步减弱了 HDAC1 诱导的肌肉肌酸激酶荧光素酶活性的抑制作用，而在 HDAC1 2R 中则相反。HDAC1 2R 无法抑制成肌作用和肌肉基因表达。总之，HDAC1 的 SUMO 化在 MyoD 信号传导中起双重作用：在未分化的成肌细胞中基础 SUMO 化状态下增强 HDAC1 对 MyoD 的去乙酰化作用，以及在成肌过程中 HDAC1 从 MyoD 上解离。
