Rgulation of vascular smooth muscle by CA2+ and CAMP

本研究的重点是钙离子抑制腺苷酸环化酶（AC 3）在调节血管平滑肌（VSM）增殖和收缩中的作用。cAMP对于VSM是抗增殖的，并且它拮抗通过激活Erk/MAP激酶途径刺激增殖的有丝分裂原的作用。此外，cAMP介导由β-2-肾上腺素能激动剂引起的VSM舒张，并抵消由α-1-肾上腺素能激动剂引起的血管收缩。我们推测，Ca 2+抑制AC 3在这两个过程中发挥了重要作用，通过releaving cAMP c检查增殖和平滑肌收缩。AC 3受包括β-肾上腺素能受体在内的GS偶联受体的强烈刺激，并受Ca 2+的抑制。Ca 2+抑制由CaM激酶II（CaMKII）介导，其在Ser-1076处磷酸化AC 3。为了探索AC 3对VSM功能的作用，我们在小鼠中破坏了AC 3基因。本提案的目的是确定Ca 2+是否通过刺激AC 3在Ser-1076处的磷酸化来抑制VSM中AC 3的活性，以确定与野生型小鼠相比，来自AC 3突变小鼠的培养的VSM细胞的增殖是否增强，并确定CaMK II突变小鼠中培养的VSM细胞的增殖是否减少。此外，我们建议在AC 3突变和CaMKII突变小鼠中检查心脏动力学参数。这些研究应提供有关有丝分裂原和肾上腺素能药物调节VSM功能的基本见解。

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.