ESTROGEN REGULATION OF SMOOTH MUSCLE BKCA CHANNELS

雌激素对平滑肌 BKCA 通道的调节

基本信息

批准号：
6719855
负责人：
Kathleen Dunlap
金额：
$ 25.07万
依托单位：
TUFTS MEDICAL CENTER
依托单位国家：
美国
项目类别：
财政年份：
2003
资助国家：
美国
起止时间：
2003-02-01 至 2005-01-31
项目状态：
已结题

项目摘要

Estrogen protects the cardiovascular system from injury by complex mechanisms that have both short- and long-term components. Longer- term estrogen actions occurs following hours of estrogen exposure and is mediated by estrogen receptors acting in the nucleus as transcription factors for growth-related genes. The rapid effects of estrogen, by contrast, occurs in a seconds-to-minutes time frame and do not require gene transcription. Project 5 of the SCOR application addresses the molecular mechanisms underlying one of the most important of these rapid effects-vasodilation. The signaling pathways underlying this non- genomic action of estrogen are incompletely understood but new data support they involve the action of nitric oxide synthase in vascular cells, elevation of nitric oxide, stimulation of vascular smooth muscle cell soluble guanylyl cyclase, and substrate phosphorylation by cGMP- dependent protein kinase (PKG). Although the key substrate(s) for PKG is unknown, new data support one likely possibility is the smooth muscle large conductance Ca2+-activated K+ (BKCa) channel. Blockade of BKCa channels in vascular rings significantly reduces estrogen-induced vasodilation, demonstrating the central role that BKCa channels in vascular rings significantly reduces estrogen-induced vasodilation, demonstrating the central role that BKCa channels play in the acute physiological response to estrogen. Experiments in Aim 1 will use BKCa channels in vascular rings significantly reduces estrogen-induced vasodilation, demonstrating the central role that BKCa channels play in the acute physiological response to estrogen. Experiments in Aim 1 will use BKCa channel activity recorded from single smooth muscle cells dissociated from mouse aorta as an assay for characterizing upstream elements in the estrogen signaling pathway that targets BKCa channels. Experiments will assess the relative contributions of endothelial and smooth muscle cells, the types of estrogen receptor involved, and the requirement for nitric oxide synthase activation. Experiments in Aim 2 will focus on the molecular mechanism by which BKCa channel activity is regulated by estrogen. We will identify the molecular variants of BKCa channel activity is regulated by estrogen. We will identify the molecular variants. variants of BKCa channels that are expressed in smooth muscles cells from mouse aorta and study the recombinant channels expressed heterologously in order to test the hypothesis that estrogen brings about BKCa channel activation through a direct PKG-dependent phosphorylation of the channel protein. Such information is essential to further understand the protective effects of estrogen on vascular tissue and may form the basis for development of new therapies for cardiovascular disease.

雌激素通过具有短期和长期成分的复杂机制保护心血管系统免受损伤。长期雌激素作用发生在雌激素暴露数小时后，并由雌激素受体介导，雌激素受体在细胞核中作为生长相关基因的转录因子。相比之下，雌激素的快速作用发生在几秒到几分钟的时间内，并且不需要基因转录。 SCOR 应用程序的项目 5 解决了这些快速效应中最重要的效应之一——血管舒张——背后的分子机制。雌激素这种非基因组作用背后的信号传导途径尚不完全清楚，但新数据支持它们涉及血管细胞中一氧化氮合酶的作用、一氧化氮的升高、血管平滑肌细胞可溶性鸟苷酸环化酶的刺激以及cGMP的底物磷酸化- 依赖性蛋白激酶（PKG）。尽管 PKG 的关键底物尚不清楚，但新数据支持一种可能的可能性是平滑肌大电导 Ca2+ 激活的 K+ (BKCa) 通道。阻断血管环中的 BKCa 通道显着减少雌激素诱导的血管舒张，证明血管环中的 BKCa 通道显着减少雌激素诱导的血管舒张的核心作用，证明 BKCa 通道在雌激素的急性生理反应中发挥的核心作用。目标 1 中的实验将使用血管环中的 BKCa 通道显着减少雌激素诱导的血管舒张，证明 BKCa 通道在雌激素的急性生理反应中发挥核心作用。目标 1 中的实验将使用从小鼠主动脉分离的单个平滑肌细胞记录的 BKCa 通道活性作为分析方法，以表征针对 BKCa 通道的雌激素信号传导通路中的上游元件。实验将评估内皮细胞和平滑肌细胞的相对贡献、所涉及的雌激素受体的类型以及一氧化氮合酶激活的要求。目标 2 中的实验将重点研究雌激素调节 BKCa 通道活性的分子机制。我们将确定 BKCa 通道活性的分子变异受雌激素调节。我们将识别分子变异。小鼠主动脉平滑肌细胞中表达的 BKCa 通道变体，并研究异源表达的重组通道，以检验雌激素通过通道蛋白的直接 PKG 依赖性磷酸化带来 BKCa 通道激活的假设。这些信息对于进一步了解雌激素对血管组织的保护作用至关重要，并可能构成开发心血管疾病新疗法的基础。