Posttranscriptional mechanisms involving microRNA-27a and b contribute to fast-specific and glucocorticoid-mediated myostatin expression in skeletal muscle
Posttranscriptional mechanisms involving microRNA-27a and b contribute to fast-specific and glucocorticoid-mediated myostatin expression in skeletal muscle
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DOI：
10.1152/ajpcell.00142.2010
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发表时间：
2011-01-01
影响因子：
5.5
通讯作者：
Loh, Amanda S.
中科院分区：
文献类型：
--
作者：
Allen, David L.;Loh, Amanda S.
艾伦DL，洛AS。涉及microRNA-27 a和B的转录后机制有助于骨骼肌中快速特异性和糖皮质激素介导的肌生长抑制素表达。美国生理学杂志细胞生理学300：C124-C137，2011年。首次发表于2010年10月27日; doi：10.1152/ajpcell.00142.2010.-抗生长因子肌生长抑制素（MSTs）的表达在快骨骼肌和慢骨骼肌之间不同，并且几乎在每种形式的肌肉萎缩中增加，但是转录机制与转录后机制对其在这些状态中的不同表达的贡献尚未确定。我们在这里表明，成熟的MSP 4 mRNA的水平在快肌与慢肌相比高六倍，在体内注射地塞米松（Dex）后，在快肌中增加两倍，在体外Dex治疗后，在C2 C12肌管中增加两倍，但MSP 4 mRNA前体mRNA的水平，转录的读数，在这些状态下只有最小和不显着的差异。此外，Dex治疗与或不与糖皮质激素受体表达构建体共转染对C2 C12肌管中小鼠MMP 3启动子活性只有适度的影响。因此，我们探索了转录后机制的潜在贡献，特别是microRNA miR-27 a和B对MMP 3表达的作用。miR-27 3 '-非翻译区（UTR）含有一个推定的识别序列，用于识别miR-27 a和B，该序列在多种脊椎动物物种中是保守的。在C2 C12肌管中，MST 3 '-UTR-荧光素酶构建体与miR-27 b表达构建体的共转染显著减弱约一半，而miR-27识别序列的突变显著增加MST 3'-UTR构建体的活性约两倍，并降低荧光素酶报告基因构建体的mRNA降解。体内慢缩肌中miR-27 a和B的表达几乎是快缩肌中的6倍，体外糖皮质激素治疗使miR-27 a的表达显著降低了近一半。最后，miR-27 a和B启动子通过与慢特异性信号分子钙调神经磷酸酶和过氧化物酶体增殖物激活受体-γ共激活因子-1 α共转染来激活。目前的数据代表了第一次证明，涉及miR-27 a和B的转录后机制可能有助于快速特异性和糖皮质激素依赖性肌生长抑制素在肌肉中的表达。
Allen DL, Loh AS. Posttranscriptional mechanisms involving microRNA-27a and b contribute to fast-specific and glucocorticoidmediated myostatin expression in skeletal muscle. Am J Physiol Cell Physiol 300: C124-C137, 2011. First published October 27, 2010; doi: 10.1152/ajpcell.00142.2010.-Expression of the antigrowth factor myostatin (MSTN) differs between fast and slow skeletal muscles and is increased in nearly every form of muscle atrophy, but the contribution of transcriptional vs. posttranscriptional mechanisms to its differing expression in these states has not been defined. We show here that levels of mature MSTN mRNA were sixfold greater in fast vs. slow muscle and were increased twofold in fast muscle in response to dexamethasone (Dex) injection in vivo and in C2C12 myotubes following Dex treatment in vitro, but that levels of MSTN pre-mRNA, a readout of transcription, only minimally and nonsignificantly differed in these states. Moreover, Dex treatment with or without cotransfection with a glucocorticoid receptor expression construct had only modest effects on mouse MSTN promoter activity in C2C12 myotubes. We therefore explored the potential contribution of posttranscriptional mechanisms, and the role of the microRNAs miR-27a and b in particular, on MSTN expression. The MSTN 3'-untranslated region (UTR) contains a putative recognition sequence for miR-27a and b that is conserved across a wide range of vertebrate species. Cotransfection of a MSTN 3'-UTR-luciferase construct with a miR27b expression construct significantly attenuated by approximately half while mutation of the miR-27 recognition sequence significantly increased by approximately twofold the activity of a MSTN 3'-UTR construct and decreased mRNA degradation of a luciferase reporter construct in C2C12 myotubes. Expression of miR-27a and b was almost sixfold greater in slow-twitch than in fast-twitch muscle in vivo, and miR-27a expression was significantly decreased by nearly half by glucocorticoid treatment in vitro. Finally, the miR-27a and b promoters were activated by cotransfection with the slow-specific signaling molecules calcineurin and peroxisome proliferator-activated receptor-gamma coactivator-1 alpha. The present data represent the first demonstration that posttranscriptional mechanisms involving miR-27a and b may contribute to fast-specific and glucocorticoid-dependent myostatin expression in muscle.