活化激酶C受体1在切应力调控血管平滑肌细胞增殖中的作用

Shear stress modulates the proliferation of vascular smooth muscle cells via receptor for activated C kinase 1

目的探讨活化激酶C受体1(receptor for actived C kinase 1,RACK1)在内皮细胞(endothelial cells,ECs)感受切应力刺激调控血管平滑肌细胞(vascular smooth muscle cells,VSMCs)增殖中的作用及其机制。方法应用平行平板流动腔系统,对联合培养的大鼠ECs和VSMCs施加1.5 Pa正常切应力(normal shear stress,NSS)和0.5 Pa低切应力(low shear stress,Low SS),应用Brd U ELISA方法检测VSMCs增殖水平,对蛋白质组学研究发现的力学响应分子RACK1表达以及Akt磷酸化,应用Western blot技术进行检测。静态条件下,应用RNA干扰技术特异性抑制VSMCs的RACK1表达,检测其对细胞增殖和Akt磷酸化的作用。应用ECs与VSMCs隔开培养和联合培养模型,检测ECs对VSMCs的RACK1表达和Akt磷酸化水平的影响。结果血管差异蛋白质组学的结果发现,与NSS组相比,RACK1在Low SS组血管组织的表达水平明显升高。细胞实验结果显示,Low SS诱导了与ECs联合培养的VSMCs增殖,上调VSMCs的RACK1表达和Akt磷酸化。静态条件下,特异性抑制VSMCs的RACK1表达后,VSMCs的增殖水平和Akt磷酸化水平均显著下降。与ECs联合培养VSMCs,其RACK1表达和Akt磷酸化水平较隔开培养组均上调。结论 VSMCs的RACK1表达受细胞接触与切应力的影响,并可能通过PI3K/Akt信号通路参与Low SS诱导的VSMCs增殖的调控。探讨VSMCs增殖功能变化及其力学生物学机制对于认识动脉粥样硬化等疾病发病机理和疾病防治有重要意义。

Objective To investigate the role of receptor for activated C kinase 1 （ RACKI ） in vascular smooth muscle cells （VSMCs） proliferation modulated by co-cultured endothelial cells （ECs） and shear stress. Methods Using EC/VSMC co-cultured parallel plate flow chamber system, two levels of shear stress i.e. low shear stress （LowSS, 0. 5 Pa） and normal shear stress （ NSS, 1. 5 Pa）, were applied for 12 h. BrdU ELISA was used to detect the proliferation of VSMCs, and Western blot was used to detect the protein expressions of RACK1 and phospho-Akt. Under the static condition, RNA interference was used to suppress the expression of RACK1 in VSMCs, and then the proliferation of VSMCs and expressions of RACK1 and phospho-Akt were detected. By using co-culture model （ECs/VSMCs） and separated culture model （ ECs//VSMCs）, the effect of ECs on ex- pressions of RACK1 and phospho-Akt in VSMCs was further analyzed. Results Comparative proteomic analysis revealed that LowSS increased the expression of RACK1 in rat aorta. In vitro experiments showed that LowSSinduced the proliferation, expressions of RACK1 and phospho-Akt in VSMCs co-cultured with ECs. Target RNA interference of RACK1 significantly decreased the proliferation of VSMCs, and the phosphorylation of Akt. In comparison with ECs//VSMCs （separated culture） group, the expression of RACK1 and phospho-Akt were both up-regulated in the VSMCs co-cultured with ECs （ ECs/VSMCs group）. Conclusions The expression of RACK1 in VSMCs was modulated by shear stress and neighboring ECs, which might induce cellular proliferation via PI3K/Akt pathway. The investigation on VSMC proliferation and the involved biomechanical mechanism will con- tribute to understanding and help preventing the pathogenesis and progress of atherosclerosis.