The myostatin propeptide and the follistatin-related gene are inhibitory binding proteins of myostatin in normal serum
The myostatin propeptide and the follistatin-related gene are inhibitory binding proteins of myostatin in normal serum
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DOI：
10.1074/jbc.m206379200
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发表时间：
2002-10-25
影响因子：
4.8
通讯作者：
Qiu, YC
中科院分区：
文献类型：
--
作者：
Hill, JJ;Davies, MV;Qiu, YC
肌生长抑制素，也称为生长和分化因子8，是负调节骨骼肌质量的转化生长因子13超家族的成员（1）。最近的实验表明，只有在酸激活后，才能通过报告基因测定法在血清中检测到肌肉生长抑制素活性，这表明天然肌肉生长抑制素作为潜在复合物循环（2）。我们使用单克隆肌生长抑制素抗体JA 16从正常小鼠和人血清中分离天然肌生长抑制素复合物。通过质谱法和蛋白质印迹法的分析表明，循环肌肉生长抑制素结合到至少两个主要蛋白质，肌肉生长抑制素前肽和卵泡抑素相关基因（FLRG）。已知肌生长抑制素前肽在体外结合并抑制肌生长抑制素（3）。在这里，我们表明，这种相互作用是相关的在体内，与大多数（>70%）的肌肉生长抑制素在血清中结合到其前肽。用重组V5-His标记的FLRG蛋白的研究证实了成熟肌生长抑制素和FLRG之间的直接相互作用。功能研究表明，FLRG抑制肌生长抑制素活性的报告基因测定。这些实验表明，肌生长抑制素前肽和FLRG是体内肌生长抑制素的主要负调节因子。
Myostatin, also known as growth and differentiation factor 8, is a member of the transforming growth factor 13 superfamily that negatively regulates skeletal muscle mass (1). Recent experiments have shown that myostatin activity is detected in serum by a reporter gene assay only after activation by acid, suggesting that native myostatin circulates as a latent complex (2). We have used a monoclonal myostatin antibody, JA16, to isolate the native myostatin complex from normal mouse and human serum. Analysis by mass spectrometry and Western blot shows that circulating myostatin is bound to at least two major proteins, the myostatin propeptide and the follistatin-related gene (FLRG). The myostatin propeptide is known to bind and inhibit myostatin in vitro (3). Here we show that this interaction is relevant in vivo, with a majority (>70%) of myostatin in serum bound to its propeptide. Studies with recombinant V5-His-tagged FLRG protein confirm a direct interaction between mature myostatin and FLRG. Functional studies show that FLRG inhibits myostatin activity in a reporter gene assay. These experiments suggest that the myostatin propeptide and FLRG are major negative regulators of myostatin in vivo.