Vasoregulation by IP3 receptor coupling to TRPC channels

描述（由申请人提供）：动脉直径是全身血压和器官血流量的主要调节因子，通过动脉肌细胞收缩性的变化进行调节。动脉肌细胞的收缩状态由几种局部和整体细胞内钙（[Ca 2 +]i）信号决定。肌醇1，4，5-三磷酸（IPS）是一种由磷脂酶C产生的第二信使，其对Ca ~（2+）信号和直径的调节作用还不清楚。传统观点认为，IPS通过刺激肌细胞中肌浆网（SR）的Ca 2+释放来收缩动脉。我们最近发表的研究结果表明，IPS引起的血管收缩是一种新的机制，它不依赖于SRCa ~（2+）的释放，而是通过IPS受体（IP 3R）和经典瞬时受体电位（TRPC）3依赖的阳离子电流（ICat）激活而发生的，但IP 3R激活激活TRPC通道调节动脉直径的机制尚不清楚。初步数据表明，肌细胞IPSR和TRPC 3通道之间的物理耦合调节IPS诱导的血管收缩。数据还表明，动脉肌细胞小窝促进这种IP 3R-TRPC通道血管调节机制。本研究的中心假设是，在脑动脉肌细胞中，小窝促进TRPC 3通道与IPSR偶联，介导血管收缩剂和IPS诱导的膜去极化、电压依赖性Ca 2+通道激活、[Ca 2 +]i升高和收缩。本研究将探讨3个具体目标：目标1将验证IP 3R与TRPC 3通道的物理耦合是IPS诱导的ICat激活所必需的假设，目标2将验证IP 3R与TRPC 3的耦合介导IPS诱导的脑动脉膜去极化、[Ca 2 +]i升高和收缩的假设。目的3将检验动脉肌细胞小窝介导TRPC 3通道与IPSR的物理和功能偶联的假设。研究这些目标的实验将整合在分子，细胞和完整组织水平上进行的技术，包括Ca 2+成像，FRET，电生理学，加压动脉肌电图和基因抑制。相关性（见说明）：调节血压和血流的机制尚未完全了解。动脉收缩力的改变与血管疾病有关，包括中风和高血压。这一提议将增强我们对调节动脉收缩性的新型信号事件的了解，并最终导致对血管疾病中发生的变化的更好了解。 (End摘要）

DESCRIPTION (provided by applicant): Arterial diameter, a principal modulator of systemic blood pressure and organ blood flow is regulated by changes in the contractility of arterial myocytes. The contractile status of arterial myocytes is determined by several local and global intracellular calcium([Ca2+]i) signals. Ca2+ signal and diameter regulation byinositol 1,4,5-trisphophate (IPS), a phospholipase C-generated second messenger is poorly understood. The conventional view has been that IPS constricts arteries by stimulatingsarcoplasmic reticulum(SR) Ca2+ release in myocytes. Our recently published data indicateda novel mechanism of IPS-induced vasoconstriction that occurred independentlyof SRCa2+ release, and via IPS receptor (IP3R)-and canonicaltransient receptor potential (TRPC) 3-dependent cation current (ICat) activation.However, mechanisms by which IP3R activation stimulates TRPC channelsin arterial myocytes to regulate arterial diameter are unclear. Preliminary data suggest that physical couplingbetween myocyte IPSRs and TRPC3 channels regulates IPS-induced vasoconstriction. Data also indicate that arterial myocyte caveolae facilitate this IP3R-TRPCchannel vasoregulatory mechanism. The central hypothesis ofthis proposal is that in cerebral artery myocytes, caveolae facilitate TRPC3 channel couplingwith IPSRs to mediate vasoconstrictor and IPS-induced membrane depolarization, voltage-dependent Ca2+ channel activation, [Ca2+]i elevation, and contraction. This proposal will investigate 3 specific aims: Aim 1 will test the hypothesis that in cerebral artery myocytes, IP3R to TRPC3 channel physical couplingis required for IPS-inducedICat activation.Aim 2 will test the hypothesis that IP3R to TRPC3 couplingmediates IPS-induced membrane depolarization, [Ca2+]i elevation, and constriction in cerebral arteries. Aim 3 will examine the hypothesis that arterial myocyte caveolae mediate physical and functional coupling of TRPC3 channelsto IPSRs. Experiments to study these aims will integrate techniques performed at molecular, cellular,and intact tissue levels, including Ca2+ imaging,FRET, electrophysiology, pressurized artery myography, and gene suppression. RELEVANCE (See instructions): Mechanisms that regulate blood pressure and flow are incompletely understood. Alterations in arterial contractility are associated with vascular diseases, including stroke and hypertension. This proposal will enhance our knowledge of a novel signaling event that modulates arterial contractility, and will ultimately lead to better insights into alterations that occur in vascular disease. (End of Abstract)