Institute of Respiratory Diseases, the Second Affiliated Hospital of the Third Military Medical University, Chongqing 400037, PR China.
Int J Biochem Cell Biol. 2011 Mar;43(3):401-8. doi: 10.1016/j.biocel.2010.11.010. Epub 2010 Nov 21.
Previous studies have demonstrated that Rab1 is involved in the export of angiotensin II (Ang II) type 1 receptor (AT1R) to the cell surface in endothelial cells and cardiomyocytes. The aim of this study was to evaluate whether the modification of Rab1-mediated endoplasmic reticulum (ER) to the Golgi body transport alters the cell surface expression and function of endogenous AT1R and AT1R-mediated phenotypic modulation in primary cultures of pulmonary artery smooth muscle cells (PASMCs). Lentiviral expression of wild-type Rab1 (Rab1WT) significantly increased cell surface expression of endogenous AT1R. However, Rab1 siRNA had the opposite effect, and attenuated downregulation of the expression of PASMCs phenotype markers, α smooth muscle actin (α-SMA) and vimentin (VIM) in rat pulmonary artery smooth muscle cells (RPASMCs) during hypoxia. Analysis of the subcellular localization of AT1R revealed that Rab1 regulated AT1R transport from the ER to the Golgi in PASMCs. Consistent with their effects on AT1R export, Rab1 modified the AT1R-mediated cell growth and the phosphorylation of signal transducing activator of transcription 3 (STAT3) during hypoxia. We found that hypoxia promoted Rab1 expression and strongly correlated with the repressed expression of PASMC phenotype markers in RPASMCs. These data strongly indicate that Rab1 modulates PASMCs function by manipulating AT1R traffic from the ER to the Golgi and provide the first evidence implicating ER-to-Golgi transport as a regulatory step for the control of RPASMCs growth.
先前的研究表明，Rab1 参与了血管紧张素 II（Ang II）1 型受体（AT1R）在血管内皮细胞和心肌细胞中从内质网（ER）向细胞表面的输出。本研究旨在评估 Rab1 介导的 ER 到高尔基体运输的修饰是否改变内源性 AT1R 的细胞表面表达和功能，以及在肺动脉平滑肌细胞（PASMCs）原代培养物中 AT1R 介导的表型调节。野生型 Rab1（Rab1WT）的慢病毒表达显著增加了内源性 AT1R 的细胞表面表达。然而，Rab1 siRNA 则产生相反的效果，并减弱了低氧条件下大鼠肺动脉平滑肌细胞（RPASMCs）中 PASMCs 表型标志物α平滑肌肌动蛋白（α-SMA）和波形蛋白（VIM）表达的下调。AT1R 的亚细胞定位分析表明，Rab1 调节了 PASMCs 中 AT1R 从 ER 向高尔基体的运输。与它们对 AT1R 输出的影响一致，Rab1 修饰了 AT1R 介导的低氧细胞生长和信号转导转录激活因子 3（STAT3）的磷酸化。我们发现低氧促进了 Rab1 的表达，并与 RPASMCs 中 PASMC 表型标志物受抑制的表达强烈相关。这些数据强烈表明，Rab1 通过操纵 AT1R 从 ER 到高尔基体的运输来调节 PASMCs 的功能，并提供了 ER 到高尔基体运输作为控制 RPASMCs 生长的调节步骤的第一个证据。
