Molecular Mechanisms for Mechanotransduction in Vascular Smooth Muscle and Endothelial cell

机械应变与表型变化有关，包括血管平滑肌细胞基因表达的改变；然而，机械转导导致核基因表达的分子基础在很大程度上还不清楚。通过使用FLEXERCEL1R应变单位，我们发现血管平滑肌细胞的循环拉伸通过自分泌机制显著激活Jun氨基末端激酶(JNK)/应激激活蛋白激酶(SAPK)。拉伸可引起培养液中ATP浓度随时间和强度的增加。拉伸诱导的JNK/SAPK的激活可通过添加清除介质中ATP的己糖激酶或apyrase来减弱。P_2受体拮抗剂和A1亚型选择性P_1受体拮抗剂均部分抑制拉伸诱导的JNK/SAK的激活。拉伸细胞的条件培养液具有刺激JNK/SAK的活性，而APYRase或P_1和P_2受体拮抗剂的加入可减弱拉伸细胞条件培养液中JNK的刺激活性。外源性ATP或腺苷的加入可诱导JNK/SAPK的剂量依赖性激活。这些结果表明，牵张通过ATP及其水解物腺苷对嘌呤受体的自分泌刺激来激活血管平滑肌细胞中的JNK/SAPK。

Mechanical strain has been implicated in phenotypic changes, including alteration of gene expression in vascular smooth muscle cells ; however, the molecular basis for mechanotransduction leading to nuclear gene expression is largely unknown. By using a FLEXERCELL^R strain unit, we found that cyclic stretching of vascular smooth muscle cells dramatically activates Jun N-terminal kinase(JNK)/stress-activated protein kinase(SAPK)through an autocrine mechanism. Stretch causes time-and strength-dependent rise of the ATP concentration in media. The stretch-induced activation of JNK/SAPK is attenuated by the addition of hexokinase or apyrase that scavenge ATP in media. Both the P_2 receptor antagonist and the A_1 subtype-selective P_1 receptor antagonist partially inhibit stretch-induced activation of JNK/SAPK.The conditioned medium from stretched cells contains an activity to stimulate JNK/SAPK.The JNK-stimulating activity in the conditioned medium from stretched cells is attenuated by the addition of apyrase or P_1 and P_2 receptor antagonists. The addition of exogenous ATP or adenosine induces dose-dependent activation of JNK/SAPK.These results indicate that stretch activates JNK/SAPK in vascular smooth muscle cells through mechanisms involving autocrine stimulation of purinoceptors by ATP and its hydrolyzed product adenosine.