Zheng Yun-Min, Mei Qi-Bing, Wang Qing-Song, Abdullaev Iskandar, Lai F Anthony, Xin Hong-Bo, Kotlikoff Michael I, Wang Yong-Xiao
Center for Cardiovascular Sciences (MC-8), Albany Medical College, 47 New Scotland Avenue, Albany, NY 12208, USA.
Cell Calcium. 2004 Apr;35(4):345-55. doi: 10.1016/j.ceca.2003.09.006.
The cellular and molecular processes underlying the regulation of ryanodine receptor (RyR) Ca(2+) release in smooth muscle cells (SMCs) are incompletely understood. Here we show that FKBP12.6 proteins are expressed in pulmonary artery (PA) smooth muscle and associated with type-2 RyRs (RyR2), but not RyR1, RyR3, or IP(3) receptors (IP(3)Rs) in PA sarcoplasmic reticulum. Application of FK506, which binds to FKBPs and dissociates these proteins from RyRs, induced an increase in Ca(2+) and Ca(2+)-activated Cl(-) and K(+) currents in freshly isolated PASMCs, whereas cyclosporin, an agent known to inhibit calcineurin but not to interact with FKBPs, failed to induce an increase in Ca(2+). FK506-induced Ca(2+) increase was completely blocked by the RyR antagonist ruthenium red and ryanodine, but not the IP(3)R antagonist heparin. Hypoxic Ca(2+) response and hypoxic vasoconstriction were significantly enhanced in FKBP12.6 knockout mouse PASMCs. FK506 or rapamycin pretreatment also enhanced hypoxic increase Ca(2+), but did not alter caffeine-induced Ca(2+) release (SR Ca(2+) content) in PASMCs. Norepinephrine-induced Ca(2+) release and force generation were also markedly enhanced in PASMCs from FKBP12.6 null mice. These findings suggest that FKBP12.6 plays an important role in hypoxia- and neurotransmitter-induced Ca(2+) and contractile responses by regulating the activity of RyRs in PASMCs.
平滑肌细胞（SMC）中兰尼碱受体（RyR）钙（Ca2+）释放调节的细胞和分子机制尚未完全明确。在此，我们发现FKBP12.6蛋白在肺动脉（PA）平滑肌中表达，并与PA肌浆网中的2型RyRs（RyR2）相关，但与RyR1、RyR3或肌醇三磷酸受体（IP3Rs）无关。应用与FKBP结合并使这些蛋白与RyRs解离的FK506，可诱导新鲜分离的肺动脉平滑肌细胞（PASMCs）中[Ca2+]i、Ca2+激活的Cl-和K+电流增加，而环孢菌素，一种已知可抑制钙调神经磷酸酶但不与FKBP相互作用的药物，未能诱导[Ca2+]i增加。FK506诱导的[Ca2+]i增加被RyR拮抗剂钌红和兰尼碱完全阻断，但未被IP3R拮抗剂肝素阻断。FKBP12.6基因敲除小鼠的PASMCs中，低氧Ca2+反应和低氧血管收缩显著增强。FK506或雷帕霉素预处理也增强了低氧诱导的[Ca2+]i增加，但未改变PASMCs中咖啡因诱导的Ca2+释放（肌浆网Ca2+含量）。去甲肾上腺素诱导的Ca2+释放和力产生在FKBP12.6基因缺失小鼠的PASMCs中也显著增强。这些发现表明，FKBP12.6通过调节PASMCs中RyRs的活性，在低氧和神经递质诱导的Ca2+及收缩反应中起重要作用。
