Ion Channels and Membrane Receptors in Pulmonary Arterial Hypertension

项目摘要/摘要 特发性肺动脉高压(IPAH)是一种进行性和致命性疾病。持续性肺 血管收缩和血管重构是IPAH PVR和PAP升高的主要原因 病人。肺动脉平滑肌细胞(PASMC)胞浆钙([Ca]Cyt)的增加是主要的 2+2+ 肺血管收缩和肺血管重塑的触发物是由于其刺激 PASMC的增殖和迁移。PASMC钙离子内流异常增强 膜受体(如CaSR)和钙通道(如TRPC6/C3)的表达有助于 多环芳烃的发展和进展。下调电压门控K+(Kv)通道表达和 PASMC上Kv电流(Ik(V))的减少有助于a)增加PASMC的收缩、增殖和 通过诱导膜去极化开放电压依赖性钙通道并提高 [CA]Cyt和b)通过抑制细胞凋亡体积减少(AVD)和维持抑制PASMC的凋亡 2+ 高[K]细胞抑制半胱氨酸酶。促进PASMC增殖和抑制PASMC凋亡均有作用 + 至肺血管壁增厚。我们的数据显示，选择性增加的miRNA参与了 转录后下调Kv通道刺激PASMC增殖和抑制PASMC IPAH患者的细胞凋亡。钙敏感受体(CaSR)--一种可激活的G蛋白偶联受体 与正常PASMC相比，Ipah-PASMC通过细胞外钙离子上调。激活中的CASR IPAH-PASMC通过二酰甘油(DAG)诱导受体操纵性钙内流(ROCE)，而IP3介导性激活 2+ 肌浆网钙离子的耗尽导致钙离子进入(SOCE)。细胞外Ca~(2+)诱导的CaSR 激活还可以抑制Kv通道，激活其他信号转导通路以诱导细胞增殖。 这项研究计划的总体目标是继续研究：i)分子和细胞 Kv通道和其他K+通道转录后下调的机制 IPAH患者PASMC中增强的miRNAs；II)遗传和分子机制 负责CaSR和受体操控(ROC)和商店操控的转录上调 (SOC)IPAH患者PASMC中的钙通道(如TRPC3/C6、TRPV1、Orai1/2和STIM1/2)；iii) CaSR介导的TRPC/Orai功能激活的细胞和病理生理机制 PASMC中通道(和STIM1/2寡聚和易位)与Kv通道的功能抑制 以及iv)参与致病钙信号转导的潜在靶点。 开发治疗PAH的新疗法或联合疗法。我们的实验室拥有广泛的研究和技术 缺氧性肺动脉高压与低氧性肺高压发病机制研究体会 肺部疾病。来自这些研究的即将到来的结果将为发展 治疗IPAH和其他形式的肺动脉高压的新疗法。

Project Summary/Abstract Idiopathic pulmonary arterial hypertension (IPAH) is a progressive and fatal disease. Sustained pulmonary vasoconstriction and vascular remodeling are the major causes for the elevated PVR and PAP in IPAH patients. An increase in cytosolic Ca ([Ca ]cyt) in pulmonary arterial smooth muscle cells (PASMC) is a major 2+ 2+ trigger for pulmonary vasoconstriction and for pulmonary vascular remodeling due to its stimulatory effect on PASMC proliferation and migration. Abnormally enhanced Ca2+ entry in PASMC because of upregulated expression of membrane receptors (e.g., CaSR) and Ca2+ channels (e.g., TRPC6/C3) contributes to the development and progression of PAH. Downregulation of voltage-gated K+ (Kv) channel expression and decrease in Kv currents (IK(V)) in PASMC contribute to a) increasing PASMC contraction, proliferation and migration by inducing membrane depolarization that opens voltage-dependent Ca2+ channels and raises [Ca ]cyt and b) inhibiting PASMC apoptosis by attenuating apoptotic volume decrease (AVD) and maintaining 2+ high [K ]cyt to inhibit caspases. Enhanced PASMC proliferation and inhibited PASMC apoptosis both contribute + to pulmonary vascular wall thickening. Our data show that selectively increased miRNAs are involved in posttranscriptionally downregulating Kv channels to stimulate PASMC proliferation and inhibit PASMC apoptosis in IPAH patients. Ca2+-sensing receptor (CaSR), a G protein-coupled receptor that can be activated by extracellular Ca2+, is upregulated in IPAH-PASMC compared to normal PASMC. Activation of CaSR in IPAH-PASMC induces receptor-operated Ca entry (ROCE) via diacylglycerol (DAG), while IP3-mediate active 2+ depletion of Ca2+ from the SR results in store-operated Ca2+ entry (SOCE). Extracellular Ca2+-induced CaSR activation also inhibits Kv channels and activate other signal transduction pathways to induce cell proliferation. The overall goal of this research program is to continue to investigate: i) the molecular and cellular mechanisms involved in the posttranscriptional downregulation of Kv channels and other K+ channels by miRNAs that are enhanced in PASMC from IPAH patients; ii) the genetic and molecular mechanisms responsible for the transcriptional upregulation of CaSR and receptor-operated (ROC) and store-operated (SOC) Ca2+ channels (e.g., TRPC3/C6, TRPV1, Orai1/2 and STIM1/2) in PASMC from IPAH patients; iii) the cellular and pathophysiological mechanisms involved in the CaSR-mediated functional activation of TRPC/Orai channels (and STIM1/2 oligomerization and translocation) and functional inhibition of Kv channels in PASMC from IPAH patients; and iv) the potential targets involved in the pathogenic Ca2+ signaling that can be used to develop novel therapy or combination therapy for PAH. Our laboratory has extensive research and technical experience in studying pathogenic mechanisms of IPAH and pulmonary hypertension associated with hypoxic lung disease. The forthcoming results from these studies will provide highly impactful insights into developing novel therapies for IPAH and other forms of pulmonary hypertension.