Actin cytoskeleton mediates BMP2-Smad signaling via calponin 1 in preosteoblast under simulated microgravity
Actin cytoskeleton mediates BMP2-Smad signaling via calponin 1 in preosteoblast under simulated microgravity
复制标题
模拟微重力下前成骨细胞中肌动蛋白细胞骨架通过钙调蛋白1介导BMP2-Smad信号传导
DOI：
10.1016/j.biochi.2017.04.015
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发表时间：
2017-07-01
期刊：
影响因子：
3.9
通讯作者：
Dai, Zhongquan
中科院分区：
文献类型：
--
作者：
Xu, Hongjie;Wu, Feng;Dai, Zhongquan
微重力影响成骨细胞的活性，诱导肌动蛋白微丝断裂，导致航天飞行过程中骨丢失。重力等机械应力通过细胞骨架的动态变化来调节细胞的功能、反应和分化，但其机制尚不完全清楚。先前，我们证明了在模拟微重力（SMG）下肌动蛋白微纤维介导的成骨细胞Cbfa 1对BMP 2的反应。本研究探讨了SMG作用下肌动蛋白细胞骨架对MC 3 T3-E1细胞BMP 2-Smad信号通路的影响及其机制。结果显示，肌动蛋白微生物活性破坏剂细胞松弛素B（CB）可降低BMP 2诱导的活化、Smad 1/5/8易位和Runx 2表达。SMG还抑制BMP 2-Smad信号传导，其被肌动蛋白细胞骨架稳定剂Jasplakinaldehyde（JAS）拯救。此外，我们发现siRNA介导的肌动蛋白结合蛋白calponin 1（CNN 1）的敲低显著促进BMP 2-Smad信号传导，并且消除CB、SMG对BMP 2-Smad信号传导的抑制和JAS的拯救作用。CNN 1过表达可抑制BMP 2诱导的p-Smad表达。双向Co-IP实验表明CNN 1可以与Smad或p-Smad蛋白相互作用。此外，CB或SMG降低磷酸化CNN 1，并增加其与Smad或p-Smad的相互作用。结合CNN 1的磷酸化抑制其肌动蛋白结合活性，这些结果表明，肌动蛋白细胞骨架解聚通过去磷酸化CNN 1阻断成骨细胞中的Smad来抑制BMP 2信号传导。因此，我们提供了新的重要见解SMG条件下的力学转导机制，这可能有助于SMG诱导的骨形成减少。(C)2017由Elsevier B. V.出版
Microgravity influences the activity of osteoblast, induces actin microfilament disruption and leads to bone loss during spaceflight. Mechanical stress such as gravity, regulates cell function, response and differentiation through dynamic cytoskeleton changes, but the mechanotrarisduction mechanism remains to be fully elucidated. Previous, we demonstrated actin microfflament mediated osteoblast Cbfa1 responsiveness to BMP2 under simulated microgravity (SMG). Here, we explored a potential molecular and its detailed mechanism of actin cytoskeleton functioning on BMP2-Smad signaling in MC3T3-E1 under SMG. Results showed that the actin microfilament-disrupting agent, cytochalasin B (CB), reduced BMP2-induced activation, translocation of Smad1/5/8 and Runx2 expression. SMG also inhibited BMP2-Smad signaling, which was rescued by actin cytoskeleton stabilizing agent, Jasplakinolide (JAS). Furthermore, we found that siRNA mediated knockdown of calponin 1 (CNN1), an actin binding protein, markedly promoted BMP2-Smad signaling and abolished both inhibition of CB, SMG on BMP2-Smad signaling and the rescue action of JAS. Overexpression of CNN1 inhibited the p-Smad induced by BMP2. Bidirectional Co-IP experiments demonstrated CNN1 could interacted with Smad or p-Smad protein. Furthermore, CB or SMG decreased the phosphorylated CNN1 and increased its interaction with Smad or p-Smad. Combined with the phosphorylation of CNN1 inhibites its actin binding activity, these results indicate that actin cytoskeleton depolymerization inhibites BMP2 signaling via blocking of Smad by dephosphorylated CNN1 in osteoblast cells. Thus, we provide new important insights into the mechanism of mechanotransduction under SMG condition, which probably contribute to bone formation decrease induced by SMG. (C) 2017 Published by Elsevier B.V.