ACUTE HORMONAL REGULATION OF STEROIDOGENESIS

营养激素强烈刺激类固醇的产生，通过作用于 类固醇合成的速率决定步骤，激素的转运 底物，胆固醇，从细胞内储存到内部 线粒体膜。在那里，胆固醇将被代谢成 孕烯醇酮。我们使用不同的方法演示了 线粒体外周型苯二氮卓类受体(PBR)介导 胆固醇从外线粒体到内线粒体的运输 膜和随后的类固醇生物合成。我们进一步 证明了PBR作为胆固醇的专一性通道发挥作用。 我们的假设是急性(秒到分钟)的激素调节 PBR受体复合体，优先位于线粒体上 膜接触部位，负责荷尔蒙的诱导 以及PBR复合体与类固醇激素的相互作用 激素诱导类固醇生成急性调节蛋白(STAR)是 负责维持更长时间的类固醇生产 (小时)。在第一个目标中，我们将建立时间和空间 PBR和STAR蛋白在hCG应答中的关系。在第二个 目的我们将研究PBR复合体的结构 对照组和促黄体生成素处理的间质线粒体接触位点的分离 细胞。寻找造成这种影响的“分子开关” 对PBR上的黄体生成素/人绒毛膜促性腺激素，我们鉴定了两个候选的PBR相关蛋白 (PAPS)。在第三个目标中，我们将调查公共规划委员会在 激素诱导的PBR、胆固醇转运和 类固醇合成。考虑到恒星发挥其作用的发现 在线粒体之外，它有可能直接作用于 PBR或通过PAP间接发送。在第四个目标中，我们将研究 STAR-PBR相互作用及其功能后果 互动。我们的目标是了解事件的顺序 负责诱导和维持类固醇激素的生成 荷尔蒙。我们的间质细胞模型系统是MA-10激素- 反应细胞系，纯化的大鼠间质细胞，R2C细胞系 表达结构性类固醇激素生成，R2C PBR阴性(-)细胞， 由基因打靶产生。

Trophic hormones acutely stimulate steroid production by acting on the rate-determining step of steroidogenesis, the transport of the substrate, cholesterol, from intracellular stores to the inner mitochondrial membrane. There, cholesterol will be metabolized to pregnenolone. Using various approaches we demonstrated that the mitochondrial peripheral-type benzodiazepine receptor (PBR) mediates the transport of cholesterol from the outer to the inner mitochondrial membrane and the subsequent steroid biosynthesis. We further demonstrated that PBR functions as a channel specific for cholesterol. It is our hypothesis that the acute (sec to min) hormonal regulation of the PBR receptor complex, preferentially located on the mitochondrial membrane contact sites, is responsible for the hormonal induction of steroidogenesis and that the interaction of the PBR complex with the hormone-induced steroidogenic acute regulatory protein (StAR) is responsible for sustaining steroid production for longer periods of time (hours). In the first aim we will establish the temporal and spatial relationship of PBR and StAR proteins in response to hCG. In the second aim we will examine the structure of the PBR complex in the mitochondrial contact sites isolated from control and LH-treated Leydig cells. In search for the "molecular switch" responsible for the effects of LH/hCG on PBR we identified two candidate PBR-associated proteins (PAPs). In the third aim, we will investigate the role of the PAPs in the hormone-induced changes in PBR, cholesterol transport, and steroidogenesis. Considering the finding that StAR exerts its effect outside the mitochondrion, it is possible that it may act directly on PBR or indirectly via a PAP. In the fourth aim we will examine the StAR-PBR interaction and the functional consequences of this interaction. Our goal is to understand the sequence of events responsible for the induction and maintenance of steroidogenesis by hormones. Our Leydig cell model systems are the MA-10 hormone- responsive cell line, purified rat Leydig cells, the R2C cell line expressing constitutive steroidogenesis, and R2C PBR negative (-) cells, generated by gene targeting.