Smooth muscle caveolae differentially regulate specific agonist induced bladder contractions
Smooth muscle caveolae differentially regulate specific agonist induced bladder contractions
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DOI：
10.1002/nau.20361
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发表时间：
2007-01-01
影响因子：
2
通讯作者：
Sullivan, M. P.
中科院分区：
文献类型：
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作者：
Cristofaro, V.;Peters, C. A.;Sullivan, M. P.
目的：小窝是富含胆固醇的质膜微区，其作为信号蛋白的螯合位点，因此可以促进、组织和整合对细胞外刺激的反应。虽然以前的研究表明，在特定的生理或病理条件下，膀胱小窝的变化，很少有人关注油这些细胞器的功能意义。因此，本研究的目的是研究小窝在受体介导的信号转导的调节中的作用，并确定小窝蛋白在膀胱组织中的存在和定位。研究方法：在大鼠膀胱组织中测量对生理性激动剂的收缩反应，在用甲基-β-环糊精耗尽膜胆固醇实现小窝破坏之前和之后。由于胆固醇补充，小窝恢复后，重复激动剂刺激。采用RT-PCR、免疫组化和Western blotting方法检测Caveolin mRNA和蛋白的表达和定位。结果如下：以下小窝破坏，收缩反应，血管紧张素II和血清素减弱，而反应缓激肽和苯肾上腺素增强。胆固醇补充恢复了对基线的反应。Carbachol和KCl诱导的收缩不受小窝破坏的影响。超微结构分析证实，损失后的胆固醇消耗与环糊精和cavcolae恢复后的胆固醇替代caveolae。检测膀胱组织中窖蛋白-1、-2和-3的基因和蛋白表达。在整个膀胱的平滑肌细胞中观察到所有三种小窝蛋白的免疫反应性。结论：胆固醇消耗对特定激动剂诱导的收缩事件和膀胱平滑肌中所有三种小窝蛋白表达的功能影响支持cavcolae在膀胱平滑肌中调节选择性G蛋白偶联受体信号传导途径中的中心作用。因此，小窝通过刺激依赖性增强或抑制膀胱收缩来差异调节膀胱平滑肌。Neurorol。Urodynam。26：71-80，2007. (c)2006 Wiley-Liss，Inc.
Aims: Caveolae are cholesterol-rich plasmalemmal microdomains that serve as sites for sequestration of signaling proteins and thus may facilitate, organize, and integrate responses to extraccllular stimuli. While previous studies in the bladder have demonstrated alterations in caveolae with particular physiologic or pathologic conditions, little attention has been focused oil the functional significance of these organelles. Therefore, the purpose of this study Was to investigate the role of caveolae in the modulation of receptor-mediated signal transduction and determine the presence and localization of caveolin proteins in bladder tissue. Methods: Contractile responses to physiologic agonists were measured in rat bladder tissue before and after disruption of caveolae achieved by depleting membrane cholesterol with methyl-beta-cyclodextrin. Stimulation with agonists was repeated after caveolae were restored as a result of cholesterol replenishment. RT-PCR, immmunohistochemistry, and Western blotting were used to determine the expression and localization of caveolin mRNA and proteins. Results: Following caveolae disruption, contractile responses to angiotensin II and serotonin were attenuated, whereas responses to bradykinin and phenylephrine were augmented. Cholesterol replenishment restored responses towards baseline. Carbachol and KCl induced contractions were not affected by caveolae disruption. Ultrastructure analysis confirmed loss of caveolae following cholesterol depletion with cyclodextrin and cavcolae restoration following cholesterol replacement. Gene and protein expression of caveolin-1, -2, and -3 was detected in bladder tissue. Immunoreactivity for all three caveolins was observed in smooth muscle cells throughout the bladder. Conclusions: The functional effects of cholesterol depletion on specific agonist-induced contractile events and the expression of all three caveolins in bladder smooth Muscle Support a central role for cavcolae in regulation of selective G-protein-coupled receptor signaling pathways in bladder smooth muscle. Thus, caveolae serve to differentially regulate bladder smooth muscle by a stimulus-dependent potentiation or inhibition of bladder contraction. Neurourol. Urodynam. 26:71-80, 2007. (c) 2006 Wiley-Liss, Inc.