Dynamic association of nitric oxide downstream signaling molecules with endothelial caveolin-1 in rat aorta
Dynamic association of nitric oxide downstream signaling molecules with endothelial caveolin-1 in rat aorta
复制标题
DOI：
10.1124/jpet.105.083634
复制
发表时间：
2005-07-01
影响因子：
3.5
通讯作者：
Webb, RC
中科院分区：
文献类型：
--
作者：
Linder, AE;McCluskey, LP;Webb, RC
传统上，内皮型一氧化氮合酶(ENOS)形成的一氧化氮合酶(NO)自由地从其生成部位扩散到平滑肌细胞，在那里它激活可溶性鸟苷酸环化酶(SGC)，产生cGMP。随后，cGMP同时激活cGMP和cAMP依赖的蛋白激酶[分别是cGMP依赖的蛋白激酶(PKG)和cAMP依赖的蛋白激酶(PKA)]，从而导致平滑肌松弛。在内皮细胞中，eNOS定位于小窝，即富含胆固醇的质膜上的小凹陷。膜胆固醇耗竭通过改变空泡结构而损害乙酰胆碱(ACh)诱导的松弛。鉴于NO在疏水环境中比在水中更易溶的性质，并假设信号转导级联中各组分的共存似乎是eNOS激活信号效率的关键决定因素，我们假设sGC、PKA和PKG的激活可能发生在质膜小窝。在内皮完整的大鼠主动脉环上，ACh、sGC激动剂3-(5‘-羟甲基-2’-呋喃)-1-苄基吲唑(YC-1)和8-bromocGMP引起的松弛在甲基-β-环糊精的存在下被削弱。SGC、PKG和PKA与小窝蛋白-1共定位于主动脉内皮细胞，这种共定位可被甲基-β-环糊精消除。甲基-β-环糊精能有效地分解内皮细胞中的小凹。综上所述，我们的结果提供了内皮小窝中sGC、PKG和PKA参与NO信号级联反应的证据，为内皮细胞介导血管平滑肌松弛提供了新的见解。
Classically, nitric oxide ( NO) formed by endothelial NO synthase ( eNOS) freely diffuses from its generation site to smooth muscle cells where it activates soluble guanylyl cyclase ( sGC), producing cGMP. Subsequently, cGMP activates both cGMP- and cAMP- dependent protein kinases [ cGMP- dependent protein kinase ( PKG) and cAMP- dependent protein kinase ( PKA), respectively], leading to smooth muscle relaxation. In endothelial cells, eNOS has been localized to caveolae, small invaginations of the plasma membrane rich in cholesterol. Membrane cholesterol depletion impairs acetylcholine ( ACh)- induced relaxation due to alteration in caveolar structure. Given the nature of NO to be more soluble in a hydrophobic environment than in water, and assuming that colocalization of components in a signal transduction cascade seems to be a critical determinant of signaling efficiency by eNOS activation, we hypothesize that sGC, PKA, and PKG activation may occur at the plasma membrane caveolae. In endothelium- intact rat aortic rings, the relaxation induced by ACh, by the sGC activator 3-( 5'- hydroxymethyl-2' furyl)- 1- benzyl indazole ( YC- 1), and by 8- bromocGMP was impaired in the presence of methyl- beta- cyclodextrin, a drug that disassembles caveolae by sequestering cholesterol from the membrane. sGC, PKG, and PKA were colocalized with caveolin- 1 in aortic endothelium, and this colocalization was abolished by methyl- beta- cyclodextrin. Methyl- beta- cyclodextrin efficiently disassembled caveolae in endothelium. In summary, our results provide evidence of compartmentalization of sGC, PKG, and PKA in endothelial caveolae contributing to NO signaling cascade, giving new insights by which the endothelium mediates vascular smooth muscle relaxation.