Podocytes respond to mechanical stress in vitro
Podocytes respond to mechanical stress in vitro
复制标题
DOI：
10.1681/asn.v123413
复制
发表时间：
2001-03-01
影响因子：
13.6
通讯作者：
Endlich, K
中科院分区：
文献类型：
--
作者：
Endlich, N;Kress, KR;Endlich, K
肾小球毛细血管压力被认为影响肾小球细胞的结构和功能。然而，目前尚不清楚足细胞是否对机械力具有固有的敏感性。在本研究中，分化的小鼠足细胞培养的柔性硅胶膜。双轴循环应力（0.5 Hz和5%的线性应变）施加到膜上长达3天。机械应力使足细胞胞体变小，突起变细变长。足细胞在不均匀的力场中没有排列。而微管网络和中间丝波形蛋白没有表现出重大变化，机械应力诱导的肌动蛋白细胞骨架的可逆重组：横向应力纤维（SF）消失和径向SF连接到肌动蛋白丰富的中心（ARC）形成。上皮细胞和成纤维细胞系没有表现出类似的应力诱导的F-肌动蛋白重组。共聚焦显微镜和电子显微镜显示了一个椭圆形和致密的丝状结构的ARC。肌球蛋白II，α-辅肌动蛋白，和足细胞特异性蛋白synaptopodin存在于径向SF，但相反的F-肌动蛋白，他们没有丰富的ARC。ARC和径向SF的形成在响应机械应力被抑制的Ca 2+流入与Ni 2+（1 mM），Rho激酶抑制与Y-27632（10 μ M）的非特异性阻断，但不通过抑制拉伸激活的阳离子通道与Gd 3+（50 μ M）。总之，机械应力诱导足细胞中肌动蛋白细胞骨架的独特重组，具有放射状SF和ARC，其在蛋白质组成上不同。F-actin在机械应力下的重组依赖于Ca ~（2+）内流和Rho激酶。本研究提供了第一个直接证据，足细胞是机械敏感的。
Glomerular capillary pressure is thought to affect the structure and function of glomerular cells. However, it is unknown whether podocytes are intrinsically sensitive to mechanical forces. In the present study, differentiated mouse podocytes were cultured on flexible silicone membranes. Bi-axial cyclic stress (0.5 Hz and 5% linear strain) was applied to the membranes for up to 3 d. Mechanical stress reduced the size of podocyte cell bodies, and processes became thin and elongated. Podocytes did not align in the inhomogeneous force field. Whereas the network of microtubules and that of the intermediate filament vimentin exhibited no major changes, mechanical stress induced a reversible reorganization of the actin cytoskeleton: transversal stress fibers (SF) disappeared and radial SF that were connected to an actin-rich center (ARC) formed. Epithelial and fibroblast cell lines did not exhibit a comparable stress-induced reorganization of the F-actin. Confocal and electron microscopy revealed an ellipsoidal and dense filamentous structure of the ARC. Myosin II, alpha -actinin, and the podocyte-specific protein synaptopodin were present in radial SF, but, opposite to F-actin, they were not enriched in the ARC. The formation of the ARC and of radial SF in response to mechanical stress was inhibited by nonspecific blockade of Ca2+ influx with Ni2+ (1 mM), by Rho kinase inhibition with Y-27632 (10 muM), but not by inhibition of stretch-activated cation channels with Gd3+ (50 muM). In summary, mechanical stress induces a unique reorganization of the actin cytoskeleton in podocytes, featuring radial SF and an ARC, which differ in protein composition. The F-actin reorganization in response to mechanical stress depends on Ca2+ influx and Rho kinase. The present study provides the first direct evidence that podocytes are mechanosensitive.