Tropomyosin variants describe distinct functional subcellular domains in differentiated vascular smooth muscle cells
Tropomyosin variants describe distinct functional subcellular domains in differentiated vascular smooth muscle cells
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DOI：
10.1152/ajpcell.00450.2010
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发表时间：
2011-06-01
影响因子：
5.5
通讯作者：
Morgan, Kathleen G.
中科院分区：
文献类型：
--
作者：
Gallant, Cynthia;Appel, Sarah;Morgan, Kathleen G.
Gallant C，阿佩尔S，Graceffa P，Leavis P，Lin JJ，Gunning PW，Schevzov G，Chaponnier C，DeGnore J，Lehman W，Morgan KG.原肌球蛋白变体描述了分化的血管平滑肌细胞中不同的功能亚细胞结构域。美国生理学杂志细胞生理学300：C1356-C1365，2011年。首次发表于2011年2月2日; doi：10.1152/ajpcell.00450.2010。原肌球蛋白（Tropomyosin，Tm）是肌动蛋白功能的重要守门蛋白。Tm异构体由四个基因编码，每个基因通过选择性剪接产生几个变体，这些变体被认为在运动、增殖和凋亡中发挥作用。平滑肌研究集中于肌胃平滑肌，其中来自α基因（Tmsm-alpha）和来自β基因（Tmsm-beta）的Tm异二聚体与收缩丝相关。在这项研究中，我们研究了Tm在分化的哺乳动物血管平滑肌（dVSM）。液相色谱-串联质谱（LC MS/MS）分析和蛋白质印迹筛选与变体特异性抗体显示，至少有五种不同的Tm蛋白表达在该组织中：Tm6（Tmsm-alpha）和Tm2从α基因，Tm1（Tmsm-beta）从β基因，Tm5NM 1从γ基因，和Tm4从δ基因。Tm6在dVSM中的丰度最高，其次是Tm1、Tm2、Tm5NM 1和Tm4。共免疫沉淀和共免疫荧光研究表明，Tm1和Tm6 coassociate不同的肌动蛋白亚型，并显示不同的细胞内定位。使用特异性抗体的细胞质γ-肌动蛋白，我们在这里报告的存在下，γ-肌动蛋白皮质细胞骨架dVSM细胞。Tm1与皮质细胞质γ-肌动蛋白共定位，并与γ-肌动蛋白共沉淀。另一方面，Tm6位于收缩束上。这些数据表明，Tm1和Tm6不形成一个经典的异源二聚体dVSM，而是描述不同的功能细胞室。
Gallant C, Appel S, Graceffa P, Leavis P, Lin JJ, Gunning PW, Schevzov G, Chaponnier C, DeGnore J, Lehman W, Morgan KG. Tropomyosin variants describe distinct functional subcellular domains in differentiated vascular smooth muscle cells. Am J Physiol Cell Physiol 300: C1356-C1365, 2011. First published February 2, 2011; doi: 10.1152/ajpcell.00450.2010.-Tropomyosin (Tm) is known to be an important gatekeeper of actin function. Tm isoforms are encoded by four genes, and each gene produces several variants by alternative splicing, which have been proposed to play roles in motility, proliferation, and apoptosis. Smooth muscle studies have focused on gizzard smooth muscle, where a heterodimer of Tm from the alpha-gene (Tmsm-alpha) and from the beta-gene (Tmsm-beta) is associated with contractile filaments. In this study we examined Tm in differentiated mammalian vascular smooth muscle (dVSM). Liquid chromatography-tandem mass spectrometry (LC MS/MS) analysis and Western blot screening with variant-specific antibodies revealed that at least five different Tm proteins are expressed in this tissue: Tm6 (Tmsm-alpha) and Tm2 from the alpha-gene, Tm1 (Tmsm-beta) from the beta-gene, Tm5NM1 from the gamma-gene, and Tm4 from the delta-gene. Tm6 is by far most abundant in dVSM followed by Tm1, Tm2, Tm5NM1, and Tm4. Coimmunoprecipitation and coimmunofluorescence studies demonstrate that Tm1 and Tm6 coassociate with different actin isoforms and display different intracellular localizations. Using an antibody specific for cytoplasmic gamma-actin, we report here the presence of a gamma-actin cortical cytoskeleton in dVSM cells. Tm1 colocalizes with cortical cytoplasmic gamma-actin and coprecipitates with gamma-actin. Tm6, on the other hand, is located on contractile bundles. These data indicate that Tm1 and Tm6 do not form a classical heterodimer in dVSM but rather describe different functional cellular compartments.