Inhibition of myogenesis by depletion of the glycogen-associated regulatory subunit of protein phosphatase-1 in rat skeletal muscle cells

作     者：Ragolia, L Zuo, Q Begum, N 

作者机构：Winthrop Univ Hosp Diabet Res Lab Mineola NY 11501 USA SUNY Stony Brook Sch Med Stony Brook NY 11794 USA 

出 版 物：《JOURNAL OF BIOLOGICAL CHEMISTRY》 (生物化学杂志)

年 卷 期：2000年第275卷第34期

页      面：26102-26108页

核心收录：

学科分类：0710[理学-生物学] 071010[理学-生物化学与分子生物学] 07[理学] 

主　　题：载体蛋白质类/遗传学 载体蛋白质类/生理学 细胞系 肌酸激酶/代谢 DNA复制 动力学 肌肉发育 肌 骨骼/酶学 肌 骨骼/生长和发育 寡脱氧核糖核苷酸类 反义/代谢 磷酰化 视网膜母细胞瘤蛋白质/代谢 转染 动物 大鼠 

摘      要：In this study, we examined the role of the glycogen-associated regulatory subunit of protein phosphatase-l (PP-1(G)) in L6 rat skeletal muscle cell myogenesis. The level of PP-1(G) was depleted by transfection with an inducible antisense oriented PP-1(G) gene. Western blot analysis of the PP-1(G)-depleted cell line revealed a 90% depletion of PP-1(G) protein and a 45% reduction in cellular PP-1 activity and abolished the ability of L6 myoblasts to differentiate into multinucleated myotubes. PP-1(G)-depleted cells also exhibited a marked reduction in the expression of the differentiation marker myogenin as well as creatine kinase. After 7 days in culture, PP-1(G)-depleted cells sustained myoblast levels of inhibitor of differentiation-a, whereas control L6 cells had a severely lower inhibitor of differentiation-a level and progressed into myotubes. Myoblasts were unable to exit the cell cycle, as measured by the impaired induction of p27 cyclin-dependent kinase inhibitor, a 2-fold increase in DNA synthesis, and elevated levels of phosphorylated retinoblastoma protein (pRb). Replacement of the PP-1(G) gene restored PP-1(G) protein expression, PP-1 enzymatic activity, and the ability to differentiate into myotubes. We conclude that PP-1(G) plays a definite role in L6 myogenesis via its regulation of PP-1 catalytic activity.