Rgulation of vascular smooth muscle by CA2+ and CAMP

本研究的重点是钙离子抑制的腺酰环化酶(AC3)在调节血管平滑肌(VSM)增殖和收缩中的作用。CAMP对VSM具有抗增殖作用，它通过激活ERK/MAP激酶通路拮抗丝裂原刺激VSM增殖的作用。此外，cAMP介导了‘-2-肾上腺素能激动剂引起的VSM的松弛，并拮抗了α-1-肾上腺素能激动剂引起的血管收缩。我们推测AC3的钙抑制在这两个过程中起主要作用，它通过释放cAMP-c抑制细胞增殖和血管收缩。AC3被包括‘-肾上腺素能受体在内的Gs偶联受体强烈刺激，并被钙抑制。Ca2抑制是由CaMKII(CaMKII)介导的，CaMKII使AC3在Ser-1076处磷酸化。为了探索AC3在血管紧张素转换酶功能中的作用，我们在小鼠中阻断了AC3基因。本研究的目的是确定钙是否通过刺激AC3在Ser-1076处的磷酸化来抑制VSM中AC3的活性，确定AC3突变小鼠培养的VSM细胞的增殖是否比野生型小鼠增强，以及CaMKII突变小鼠的培养VSM细胞的增殖是否被抑制。此外，我们建议检测AC3突变和CaMKII突变小鼠的心脏动力学参数。这些研究应该为有丝分裂原和肾上腺素能药物对VSM功能的调节提供基本的见解。

This proposal focuses on the role of the Ca2+ inhibited adenylyl cyclase (AC3) in the regulation of vascular smooth muscle (VSM) proliferation and smooth muscle contraction. cAMP is anti-proliferative for VSM and it antagonizes the actions of mitogens that stimulate proliferation through activation of the Erk/MAP kinase pathway. Furthermore, cAMP mediates relaxation of VSM caused by '-2-adrenergic agonists and counteracts vasoconstriction caused by a -1-adrenergic agonists. We hypothesize that Ca2+ inhibition of AC3 plays a major role in both processes by releaving the cAMP c check on proliferation and smooth muscle constriction. AC3 is strongly stimulated by Gs-coupled receptors including '-adrenergic receptors and it is inhibited by Ca2+. Ca2+ inhibition is mediated by CaM kinase II (CaMKII) which phosphorylates AC3 at Ser-1076. To explore the role of AC3 for VSM function we disrupted the AC3 gene in mice. The objectives of this proposal are to determine if Ca2+ inhibits the activity of AC3 in VSM by stimulating the phosphorylation of AC3 at Ser-1076, to determine if proliferation of cultured VSM cells from AC3 mutant mice is enhanced is enhanced compared to wild type mice, and to determine if proliferation of cultured VSM cells is reduced in CaMKII mutant mice. In addition, we propose to examine cardiodynamic parameters in AC3 mutant and CaMKII mutant mice. These studies should provide fundamental insight concerning the regulation of VSM functions by mitogens and adrenergic agents.