FUNCTION AND REGULATION OF SOMATOSTATIN RECEPTORS

生长抑素受体的功能和调节

• 批准号: 2443958
• 负责人: AGNES SCHONBRUNN
• 金额: $ 24.46万
• 依托单位: UNIVERSITY OF TEXAS HLTH SCI CTR HOUSTON
• 依托单位国家: 美国
• 财政年份: 1995
• 资助国家: 美国
• 起止时间: 1995-07-01 至 1999-06-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/2443958
• 关键词: G protein; RNase protection assay; cell type; hormone receptor; hormone regulation /control mechanism; immunoprecipitation; laboratory rabbit; messenger RNA; northern blottings; peptide hormone analog; phosphorylation; polymerase chain reaction; protein isoforms; protein structure function; receptor binding; receptor coupling; receptor expression; receptor sensitivity; second messengers; somatostatin; tissue /cell culture; western blottings

Somatostatin (SRIF) is a neuropeptide which acts as a hormone, a neurotransmitter or an autocrine regulator to inhibit secretion and/or proliferation in endocrine, exocrine, neuronal and tumor cells. SRIF has been implicated in numerous physiological processes ranging from growth to memory as well as in several disorders including endocrine cancers and Alzheimer's disease. The biological actions of this peptide are initiated by binding to plasma membrane receptors which are coupled to effector enzymes and ion channels via o proteins. Recently five related SRIF receptor (sstr) genes have been identified by molecular cloning. These sstr subtypes are believed to serve unique biological roles by virtue of their tissue specific expression and particular biochemical properties. However, we do not understand the function of any individual sstr in its normal cellular milieu. Such studies have been difficult because SRIF- responsive tissues and cell lines often express multiple sstr's and, in the absence of subtype specific SRIF analogs, the actions of individual receptors cannot be identified. Moreover, sstr function depends on cellular environment so that the behavior of a receptor expressed in heterologous cells does not necessarily mimic that of endogenous receptors. This proposal has two overall goals: (l) characterize the signal transduction mechanisms activated by sstr subtypes, and (2) elucidate the mechanisms involved in the regulation of sstr's. In the last award period, we developed several receptor antibodies each of which immunoprecipitates the corresponding sstr subtype specifically. Moreover, we developed conditions such that the G-proteins coupled to sstr's in membranes remain receptor associated in the immunoprecipitate. We propose to characterize the G proteins coupled to each sstr subtype in different target cells by immunoprecipitating each receptor and identifying the associated G protein subunits with G protein specific antisera. We will therefore determine how cellular milieu affects the specificity of sstr-G protein coupling. Further, we will use biochemical and electrophysiological techniques to identify the effectors regulated by individual receptor subtypes in different target cells. We also propose to examine the mechanisms involved in sstr desensitization and regulation. Some SRIF responses are rapidly desensitized whereas others are not. Moreover, we have shown that sstr's are subject to chronic regulation by several different hormones. We propose to determine how specific hormonal treatments alter the expression of different sstr subtype mRNAs and proteins. In addition, we will examine the role of receptor phosphorylation in SRIF desensitization. Together these studies will elucidate the cellular mechanisms by which SRIF induces its biological actions and will identify the molecular basis for hormone induced changes in cellular responsiveness to SRIF.

生长抑素(SRIF)是一种神经肽，作为一种激素，一种 神经递质或自分泌调节剂抑制分泌和/或 内分泌、外分泌、神经细胞和肿瘤细胞的增殖。SRIF有 牵涉到许多生理过程，从生长到 与记忆以及包括内分泌癌和 阿尔茨海默氏症。这种多肽的生物学作用是由 通过与连接到效应器的质膜受体结合 通过o蛋白的酶和离子通道。最近五个相关的SRIF 受体(Sstr)基因已通过分子克隆获得。这些 SSTR亚型被认为通过以下方式发挥独特的生物学作用 它们的组织特异性表达和特殊的生化特性。 然而，我们并不了解任何单独的sstr在ITS中的作用。 正常的细胞环境。这样的研究一直很困难，因为SRIF- 有反应的组织和细胞系通常表达多个sstr和，在 没有亚型特定的SRIF类似物，个体的行为 受体无法识别。此外，sstr函数依赖于 细胞环境，因此受体的行为表达在 异源细胞不一定模仿内源性细胞 感受器。这一建议有两个总体目标：(L)描述 SSTR亚型激活的信号转导机制，以及(2) 阐明调控sstr的机制。 在去年的颁奖期间，我们开发了几种受体抗体，每种抗体 免疫共沉淀法特异性地沉淀相应的sstr亚型。此外， 我们开发了这样的条件，使G蛋白与SSTR的偶联 在免疫沉淀物中，膜仍然是与受体相关的。我们建议 不同SSTR亚型偶联的G蛋白的特征 通过免疫沉淀每个受体并识别靶细胞 G蛋白亚基与G蛋白特异性抗血清结合。我们会 因此，确定细胞环境如何影响sstr-G的特异性 蛋白质偶联。此外，我们将使用生化和 用电生理学技术识别受 不同靶细胞中的不同受体亚型。我们还提议 探讨sSTR脱敏和脱敏的机制 监管。有些SRIF反应会迅速脱敏，而另一些则会迅速脱敏 不是的。此外，我们已经证明，sstr容易患上慢性疾病。 受几种不同荷尔蒙的调节。我们建议确定如何 特定激素治疗改变不同sStr的表达 亚型mRNAs和蛋白质。此外，我们还将研究 SRIF脱敏中的受体磷酸化。把这些研究放在一起 将阐明SRIF诱导其发生的细胞机制 并将确定荷尔蒙的分子基础 诱导细胞对SRIF的反应性改变。