Realtime imaging analysis of tyrosine phosphorylation in response to hemodynamic forces

&lt；目的&gt；包括血管和心脏在内的心血管系统总是受到血液动力学压力，如血压和血液流动。我们研究了血管组织的机械转导机制，特别是酪氨酸激酶、蛋白激酶C和Rho/Rho激酶系统的相互作用。我们的研究结果总结如下：结果和讨论(1)机械传感器分子的药理学特性我们研究了两条将机械力转化为细胞内信号的途径。1)Gd离子敏感型牵张激活的阳离子通道(SA)：犬大脑动脉对牵张反应的肌源性收缩是通过以下过程启动的：通过激活SA通道使细胞膜去极化，随后通过L型钙通道引起胞内钙的增加，导致钙激活的CI通道开放，CI的外流进一步使膜去极化。2)RGD肽敏感整合素：Stretch…更多地诱导20kd肌球蛋白轻链的多重磷酸化，肌原张力低。酪氨酸激酶、蛋白激酶C和Rho/Rho激酶系统的相互作用对产生这种多重磷酸化特别重要。此外，我们还发现RGD-肽敏感和-不敏感的通路参与牵张引起的血管收缩前列腺素类物质的产生，包括未转化的前列腺素H_2。(2)机械传导的时间药理学：血管腔内压升高引起大鼠脑动脉的时相和紧张性肌源性收缩。Rho/Rho激酶参与时相和紧张性反应，而蛋白激酶C在肌源性收缩的紧张期起作用。这两种酶似乎在生肌机制中都起到了钙增敏的作用。(3)机械转导的生理学方面1)肺动脉高压：低压低氧所致的小鼠肺动脉高压。在肺动脉高压时，可能存在肺动脉过度伸展的情况。因此，小鼠肺细胞外信号调节蛋白激酶(ERK1/2)被特异性激活，ERK1/2是机械信号转导的指标。2)蛛网膜下腔出血后脑血管痉挛(CVS)：CVS被认为是由一种氧应激物--红细胞衍生的氧合血红蛋白引起的。我们注意到CVS与机械应激的收缩和其他反应之间的相关性，这与酪氨酸激酶、蛋白激酶C和Rho/Rho激酶系统的功能作用有关。因此，心血管系统机械转导的研究无疑有助于阐明心血管疾病血管痉挛发作和病理性重构的机制，并具有潜在的治疗意义。较少

<Purpose> Cardiovascular systems including blood vessels and heart are always subjected to hemodynamic stresses such as blood pressure and blood flow. We studied the mechanism of mechanotransduction of vascular tissues with special regard to the interactive role of tyrosine kinase, protein kinase C, and Rho/Rho kinase systems. We summarize herewith our results as following:<Results and Discussion> (1) Pharmacological characteristics of mechanosensor moleculesWe investigated two pathways transforming mechanical force to intracellular signaling. 1) Gadolinium ion-sensitive stretch-activated cation channel (SA): Myogenic contraction of canine cerebral artery in response to stretch was initiated by the following process; membrane was depolarized by activation of SA channel, and subsequent increase in cytosolic Ca occurred through L-type Ca channel, which led to opening of Ca-activated CI channel, and efflux of CI further depolarized the membrane. 2) RGD-peptide sensitive integrin: Stretch … More induced multiple phosphorylation of 20kd myosin light chain with low myogenic tone. The interactive role of tyrosine kinase, protein kinase C, and Rho/Rho kinase systems are in particular of importance to produce this multiple phosphorylation. Furthermore, we found that RGD-peptide sensitive and -insensitive pathways were involved in stretch-induced production of vasoconstrictor prostanoids, including untransformed prostaglandinH2, in rabbit pulmonary artery with endothelium.(2) Chronophamacology of mechanotransductionIncrease in intraluminal pressure produced phasic and tonic myogenic contraction of rat cerebral artery. Rho/Rho kinase was involved in both phasic and tonic responses, whereas protein kinase C played a role in the tonic phase of myogenic contraction. Both kinases seem to act as a Ca sensitizer in the myogenic mechanism.(3) Pasthophysiological aspects of mechanotransduction1) Pulmonary hypertension: Hypobaric hypoxia induced pulmonary hypertension in mice. It is possible that pulmonary arteries are stretched excessively in pulmonary hypertension. Consequently, extracellular signal-regulated protein kinase (ERK1/2), an index of mechanotransduction, of murine lung was specifically activated. 2) Cerebral vasospasm after subarachnoid hemorrhage (CVS): CVS is considered to be elicited by erythrocyte-derived oxyhemoglobin, an oxygen stresser. We notice the relevance between CVS and the contractile and other responses to mechano-stress in terms of functional roles of tyrosine kinase, protein kinase C, and Rho/Rho kinase systems. Thus, the study of the mechanotransduction in cardiovascular system surely aids in clarifying the mechanisms underlying vasospastic episodes and the initiation of pathologic remodeling in cardiovascular diseases, and potentially has therapeutic consequences. Less