Silencing of p21-activated kinase attenuates vimentin phosphorylation on Ser-56 and reorientation of the vimentin network during stimulation of smooth muscle cells by 5-hydroxytryptamine.
Silencing of p21-activated kinase attenuates vimentin phosphorylation on Ser-56 and reorientation of the vimentin network during stimulation of smooth muscle cells by 5-hydroxytryptamine.
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DOI：
10.1042/bj20050065
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发表时间：
2005-06
期刊：
影响因子：
--
通讯作者：
D. Tang;Ying Bai;S. Gunst
中科院分区：
文献类型：
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作者：
D. Tang;Ying Bai;S. Gunst
波形蛋白中间丝在内皮细胞和成纤维细胞中对血小板源性生长因子和表皮生长因子刺激的反应进行空间重组。在本研究中，波形蛋白网络在未受刺激的平滑肌细胞中表现出弯曲的丝状结构。波形蛋白丝在5-羟色胺（5-HT;血清素）刺激后变直并沿着细胞长轴排列。用5-HT刺激平滑肌细胞也诱导Ser-56上的波形蛋白磷酸化。用小干扰RNA处理细胞选择性下调PAK 1（p21激活激酶1）的表达，而不影响平滑肌α-肌动蛋白的含量。PAK 1的沉默抑制了波形蛋白网络响应5-HT刺激的位点特异性磷酸化和空间重排。无论是破坏应力纤维的细胞松弛素D，也不抑制蛋白酪氨酸磷酸化的影响空间重组的波形蛋白中间丝在5-HT刺激。此外，5-HT刺激平滑肌细胞增加了可溶性波形蛋白与不溶性波形蛋白的比例。PAK 1沉默减弱了5-HT刺激后可溶性与不溶性波形蛋白比率的增加。这些结果表明，PAK介导的位点特异性磷酸化的波形蛋白可能发挥作用，在调节波形蛋白中间丝重组过程中与5-HT刺激平滑肌细胞。
Vimentin intermediate filaments undergo spatial reorganization in endothelial cells and fibroblasts in response to stimulation with platelet-derived growth factor and epidermal growth factor. In the present study, the vimentin network exhibited a curved filamentous structure in unstimulated smooth muscle cells. Vimentin filaments became straight and were arranged along the long axis of cells upon stimulation with 5-hydroxytryptamine (5-HT; serotonin). Stimulation of smooth muscle cells with 5-HT also induced phosphorylation of vimentin on Ser-56. Treatment of cells with small interfering RNA selectively down-regulated the expression of PAK1 (p21-activated kinase 1) without affecting the content of smooth muscle alpha-actin. The silencing of PAK1 inhibited the site-specific phosphorylation and spatial rearrangement of the vimentin network in response to stimulation with 5-HT. Neither the disruption of stress fibres by cytochalasin D nor the inhibition of protein tyrosine phosphorylation affects the spatial reorganization of vimentin intermediate filaments in response to stimulation with 5-HT. In addition, stimulation of smooth muscle cells with 5-HT increased the ratio of soluble to insoluble vimentin. PAK1 silencing attenuated increases in the ratio of soluble to insoluble vimentin upon stimulation with 5-HT. These results suggest that the PAK-mediated site-specific phosphorylation of vimentin may play a role in regulating the reorganization of vimentin intermediate filaments during stimulation of smooth muscle cells with 5-HT.