Realtime imaging analysis of tyrosine phosphorylation in response to hemodynamic forces

<目的>包括血管和心脏在内的心血管系统经常受到血压和血流等血流动力学压力的影响。我们研究了血管组织机械转导的机制，特别关注酪氨酸激酶、蛋白激酶C和Rho/Rho激酶系统的相互作用。<结果与讨论>(1)机械传感器分子的药理特性我们研究了将机械力转化为细胞内信号的两条途径。1)钆离子敏感拉伸激活阳离子通道（SA）：犬脑动脉肌源性收缩响应拉伸的过程如下；细胞膜通过SA通道激活去极化，随后胞质内Ca通过l型Ca通道增加，导致Ca激活的CI通道打开，CI的外排进一步使细胞膜去极化。2) rgd -肽敏感整合素：Stretch…More诱导20kd肌球蛋白轻链多次磷酸化，低肌张力。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，我们发现rgd -肽敏感和-不敏感通路参与拉伸诱导血管收缩剂前列腺素的产生，包括未转化的前列腺素h2。(2)机械转导的时效学：腔内压升高引起大鼠脑动脉相性和强直性肌原性收缩。Rho/Rho激酶参与了肌原性收缩的强直期和相位反应，而蛋白激酶C参与了肌原性收缩的强直期。这两种激酶似乎在肌生成机制中起钙增敏剂的作用。(3)机械转导的病理生理方面1)肺动脉高压：低压缺氧诱导小鼠肺动脉高压。肺动脉高压可能是肺动脉过度伸展所致。因此，细胞外信号调节蛋白激酶（ERK1/2）是小鼠肺机械转导的指标，被特异性激活。2)蛛网膜下腔出血后脑血管痉挛（CVS）： CVS被认为是由红细胞衍生的氧应激因子血红蛋白引起的。根据酪氨酸激酶、蛋白激酶C和Rho/Rho激酶系统的功能作用，我们注意到CVS与机械应力收缩和其他反应之间的相关性。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中血管痉挛发作和病理性重构的机制，并可能具有治疗意义。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