Activation of protein kinase A by endothelin-1

描述（由申请人提供）：血管活性肽内皮素-1（ET 1）通过多种信号通路刺激血管平滑肌收缩并促进血管平滑肌肥大。以前，它已被大量报道，ET 1可以提高cAMP在血管平滑肌细胞（VSMC），但这种海拔的功能后果尚未探讨，因为这种影响是温和的。我们发现，尽管ET 1对cAMP的影响很小，但它可以显著激活蛋白激酶A（PKA）-一种被认为与抑制VSMC收缩和增殖有关的效应酶。然而，我们的初步数据表明，在VSMC中，ET 1诱导的PKA激活与β受体激动剂异丙肾上腺素（ISO）诱导的PKA激活在几个关键方面有所不同：（i）ET 1诱导的PKA激活持续时间比ISO诱导的持续时间短得多;（ii）ET 1诱导的PKA激活促进肥大生长，而ISO诱导的PKA激活没有这种作用;和（iii）当被ET 1激活时，PKA磷酸化蛋白质的补体，其中一些与ISO刺激期间被PKA磷酸化的蛋白质不同。这些初步的数据表明，PKA激活的模式（ET 1与ISO）深刻地影响了VSMC中PKA激活的一些功能后果。本研究的主要目的是：a）确定ET 1激活PKA的信号传导机制，以及它们与ISO诱导的PKA信号传导机制的不同之处; B）开始了解PKA如何促进ET 1诱导的VSMC肥大，以及为什么在ISO激活时PKA不这样做。为了实现我们的主要目标，我们提出了三个具体的目标：1）确定瞬时PKA激活ET 1在VSMC中的机制; 2）检查蛋白激酶B/Akt是否被磷酸化和激活ET 1在PKA依赖的方式;和3）确定差异磷酸化的蛋白质由ET 1或ISO在PKA依赖的方式。这项研究是基本的和实际的重要性，因为它可能会发现PKA激活的新的激动剂特异性后果，并可能导致更好地了解高血压，动脉粥样硬化，再狭窄和血管痉挛的发病机制。

DESCRIPTION (provided by applicant: The vasoactive peptide endothelin-1 (ET1) stimulates contraction and promotes hypertrophy of vascular smooth muscle, through diverse signaling pathways. Previously, it has been variably reported that ET1 can elevate cAMP in vascular smooth muscle cells (VSMC), but the functional consequences of this elevation have not be explored because the effects were modest. We have found that despite its minimal effect on cAMP, ET1 can dramatically activate protein kinase A (PKA) - an effector enzyme thought to be implicated in inhibition of VSMC contraction and proliferation. However, our preliminary data indicates that in VSMC, PKA activation by ET1 differs from that induced by beta-agonist, isoproterenol (ISO), in several key ways: (i) the duration of PKA activation by ET1 is much shorter than that induced by ISO; (ii) ET1-induced PKA activation promotes hypertrophic growth, whereas ISO-induced PKA activation has no such effect; and (iii) when activated by ET1, PKA phosphorylates a complement of proteins, some of which are different from those phosphorylated by PKA during ISO stimulation. These preliminary data indicate that the mode of PKA activation (ET1 vs. ISO) profoundly influences some of the functional consequences of PKA activation in VSMC. The major objective of this proposal is a) to identify the signaling mechanisms of PKA activation by ET1 and how they are different from those induced by ISO, and b) to begin understanding how PKA promotes ET1-induced hypertrophy of VSMC and why it does not do this when activated by ISO. To achieve our major objective, we propose three specific aims: 1) identify the mechanisms of transient PKA activation by ET1 in VSMC; 2) examine whether protein kinase B/Akt is phosphorylated and activated by ET1 in a PKA-dependent manner; and 3) identify the proteins that are differentially phosphorylated by ET1 or ISO in a PKA-dependent manner. This study is of fundamental and practical importance, as it may uncover the new agonist-specific consequences of PKA activation and may lead to a better understanding the pathogenesis of hypertension, atherosclerosis, restenosis and vasospasm.