Muscle cells are routinely subjected to mechanical stretch but the impact of stretch on the organization of membrane domains is unknown. In this study, we characterize the effect of stretch on GPCR-Gαq protein signaling. Activation of this pathway leads to an increase in intracellular calcium. In muscle cells, GPCR-Gαq signals are enhanced when these proteins are localized in caveolae membrane domains whose curved structure can flatten with stretch. When we statically stretch rat aortic smooth muscle A10 cells by 1-5%, cellular calcium appears unperturbed as indicated by a calcium indicator. However, when we activate the bradykinin type 2 receptor (B2R)/Gαq pathway, we observe a loss in calcium that appears to be mediated through perturbations in calcium-activated stretch receptors. In contrast, if we apply oscillating stretch, calcium levels are enhanced. We tested whether the observed changes in B2R-Gαq calcium signals were caused by stretch-induced disruption of caveolae using a combination of silencing RNA technology and growth conditions. We find that stretch changes the ability of monoclonal caveolin antibodies to bind caveolae indicating a change in configuration of the domains. This change is seen by the inability of cells to survive stretch cycles when the level of caveolae is significantly reduced. Our studies show that the effect of calcium signals by mechanical stretch is mediated by the type of stretch and the amount of caveolae.

中文翻译：

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机械拉伸重新定义了膜Gαq-钙信号复合物。

肌肉细胞通常受到机械拉伸，但是拉伸对膜结构域组织的影响尚不清楚。在这项研究中，我们表征了拉伸对GPCR-Gαq蛋白信号传导的影响。该途径的激活导致细胞内钙的增加。在肌肉细胞中，当这些蛋白质位于弯曲结构可以随着拉伸而变平的海绵膜结构域中时，GPCR-Gαq信号就会增强。当我们将大鼠主动脉平滑肌A10细胞静态拉伸1至5％时，钙离子指示剂表明细胞钙似乎不受干扰。但是，当我们激活缓激肽2型受体（B2R）/Gαq途径时，我们观察到钙的丢失似乎是由钙激活的舒张受体的扰动介导的。相反，如果我们采用振荡拉伸，钙水平提高。我们测试了观察到的B2R-Gαq钙信号变化是否是由于沉默RNA技术和生长条件的结合而导致的拉伸诱导的小窝破坏。我们发现，拉伸改变了单克隆小窝蛋白抗体结合小窝蛋白的能力，表明结构域的改变。当小窝水平显着降低时，细胞无法在拉伸周期中存活，就可以看到这种变化。我们的研究表明，机械拉伸对钙信号的影响是由拉伸的类型和小窝的数量介导的。我们发现，拉伸改变了单克隆小窝蛋白抗体结合小窝蛋白的能力，表明结构域的改变。当小窝水平显着降低时，细胞无法在拉伸循环中存活，就可以看出这一变化。我们的研究表明，机械拉伸对钙信号的影响是由拉伸的类型和小窝的数量介导的。我们发现，拉伸改变了单克隆小窝蛋白抗体结合小窝蛋白的能力，表明结构域的改变。当小窝水平显着降低时，细胞无法在拉伸周期中存活，就可以看到这种变化。我们的研究表明，机械拉伸对钙信号的影响是由拉伸的类型和小窝的数量介导的。