Actions of Estrogen on Uterine Artery Endothelium

点击翻译按钮获取中文摘要

Project Summary Our work funded by this RO1 during this last funding cycle has established that endogenous hydrogen sulfide (H2S) produced by selective upregulated H2S synthesizing enzyme cystathionine β-synthase (CBS) is a new uterine artery (UA) dilator system contributing to estrogen-induced and pregnancy-associated rises in uterine blood flow. This novel pathway has reshaped the view how uterine hemodynamics is regulated during normal pregnancy. More recently, we reported that H2S stimulates human UA relaxation via activating smooth muscle (SM) large conductance Ca2+-activated voltage-gated potassium (BKCa) channels; yet, how H2S mediates estrogen-induced UA dilation in normal and complicated pregnancies remains largely unknown. Formation of -SSH groups on reactive cysteine(s) in proteins, referred to as sulfhydration or persulfidation, has emerged as the main signaling route for H2S to exert its biological function. Sulfhydration converts free thiols (-SH) to persulfide (-SSH) resulting in increased reactivity of modified cysteines due to increased nucleophilicity of SSH compared with SH. In this competitive renewal RO1 application, we present new data showing that estrogen and pregnancy can significantly stimulate protein sulfhydration in human UA; and more interestingly, the elevated levels of total sulfhydrated proteins and sulfhydrated β1 and γ1 subunits of BKCa channels in human UA in normal pregnancy is significantly reduced in preeclampsia. Thus, we propose to test a novel hypothesis herein that augmented CBS/H2S sulfhydrates the increased β1 and γ1 BKCa (via estrogen receptor-dependent transcription) resulting in activation of SM BKCa to mediate estrogen-induced UA dilation in normal pregnancy and this mechanism is impaired in preeclampsia. This conjecture will be tested by two specific aims targeting on determining the estrogen-responsive BKCa channels and how sulfhydration results in activation of these BKCa channels pertaining to UA dilation in pregnancy and preeclampsia, with comprehensive biochemical, cellular, molecular, pharmacological, and physiological and electrophysiology approaches using in vitro primary cell culture models of UA smooth muscle cells, ex vivo studies of human main UA samples associated with different estrogens status from hysterectomy and myometrial UA samples from normal and preeclamptic pregnancies, and in vivo rat models to study the role of exogenous and endogenous estrogens in vivo. The proposed studies will establish a novel mechanism for BKCa channel activation via sulfhydrating its regulatory β1 and γ1 subunits to broadly impact on ion channel biology. These studies will comprehend specific mechanisms for activation of the estrogen-responsive SM BKCa channels pertaining to estrogen-induced UA dilation in pregnancy and preeclampsia. Data obtained will advance our understanding of estrogens and uterine blood flow biology, informing new pathways to assist the development of alternative strategies for combating preeclampsia. New data obtained will also shed lights on the understanding of the cardiovascular protective effects of estrogens. 1