Rgulation of vascular smooth muscle by CA2+ and CAMP

本文主要研究Ca2+抑制腺苷酸环化酶（AC3）在调节血管平滑肌（VSM）增殖和平滑肌收缩中的作用。cAMP对VSM具有抗增殖作用，它可以拮抗通过激活Erk/MAP激酶途径刺激增殖的有丝分裂原的作用。此外，cAMP介导‘-2-肾上腺素能激动剂引起的VSM松弛，并抵消’- 1-肾上腺素能激动剂引起的血管收缩。我们假设Ca2+抑制AC3通过释放cAMP c对增殖和平滑肌收缩的检查在这两个过程中起主要作用。AC3受包括'-肾上腺素能受体在内的gs偶联受体的强烈刺激，并受Ca2+的抑制。Ca2+抑制是由CaM激酶II （CaMKII）介导的，CaMKII使AC3在Ser-1076位点磷酸化。为了探索AC3在VSM功能中的作用，我们破坏了小鼠的AC3基因。本研究的目的是确定Ca2+是否通过刺激AC3 Ser-1076位点的磷酸化来抑制VSM中AC3的活性，确定与野生型小鼠相比，AC3突变小鼠培养的VSM细胞的增殖是否增强，以及确定CaMKII突变小鼠培养的VSM细胞的增殖是否降低。此外，我们建议检测AC3突变体和CaMKII突变体小鼠的心脏动力学参数。这些研究为有丝分裂原和肾上腺素能药物对VSM功能的调控提供了基础的认识。

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.