DESENSITIZATION OF CALCIOTROPIC HORMONE RECEPTORS

促钙激素受体脱敏

• 批准号: 2145923
• 负责人: MARVIN C GERSHENGORN
• 金额: $ 20.02万
• 依托单位: WEILL MEDICAL COLL OF CORNELL UNIV
• 依托单位国家: 美国
• 财政年份: 1993
• 资助国家: 美国
• 起止时间: 1993-05-01 至 1997-04-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/2145923
• 关键词: G protein; adenylate cyclase; calcitonin; confocal scanning microscopy; gene mutation; high performance liquid chromatography; hormone receptor; hormone regulation /control mechanism; human genetic material tag; immunoprecipitation; nucleic acid chemical synthesis; phospholipase C; protein structure function; receptor coupling; receptor expression; receptor sensitivity; tissue /cell culture; transfection

The long-term objectives of this research program are to elucidate the mechanisms through which calcitonin (CT) regulates its own responses in tissues such as bone and kidney. Evidence has been presented that stimulation of adenylyl cyclase (AC) by CT desensitizes during agonist action. Although there are other mechanisms by which desensitization can occur, a major site of modification causing desensitization is the receptor itself. With other guanine nucleotide-binding regulatory (G) protein-coupled receptors (GPCRs), desensitization has been found to be caused by receptor-G protein uncoupling, receptor internalization and receptor down-regulation. We will test the following hypothesis regarding the mechanisms involved in desensitization of responses to CT. Amino acid residues in the putative carboxyl termini and third intracellular loops of the CT receptor mediate receptor-G protein uncoupling, receptor internalization and receptor down-regulation, which occurs in part by stimulating receptor degradation. To test this hypothesis, we will pursue the following Specific Aims: 1) To design and construct a synthetic gene for the CT receptor. This goal when accomplished will have a major practical impact on research in this field because it will greatly facilitate the study of this receptor by molecular genetic techniques. 2) To establish cell systems with transfected CT receptor cDNAs that show stimulation and desensitization of both AC and phosphoinoitide-specific phospholipase C (PPlase), receptor internalization and receptor down-regulation. 3) To determine the structural features of the CT receptor that interact with a G protein(s) to activate AC and PPlase. 4) To determine the structural features of the CT receptor that mediate receptor-G protein uncoupling, and receptor internalization and down-regulation. Molecular genetics will be used to construct the synthetic genes and to mutate the receptor DNAs. Desensitization (or tachyphylaxis), which limits the magnitude and duration of responses, limits the efficacy of drugs that act through these receptors. Therefore, one important reason to understand the mechanism of desensitization is to be able to design non-peptide drugs, which would not require parenteral nor intranasal administration, that may circumvent desensitization. These drugs could enhance the efficacy of receptor agonists by inhibiting desensitization or be agonists themselves of the CT-R. These agents could be used to treat osteoporosis.

该研究计划的长期目标是阐明 降钙素（CT）调节其自身反应的机制 骨骼和肾脏等组织。 有证据表明 在激动剂期间，CT脱敏刺激腺苷酸环化酶（AC） 行动。 尽管还有其他机制可以使脱敏 发生，导致脱敏的主要修饰部位是 受体本身。 与其他鸟嘌呤核苷酸结合调节（G） 蛋白质偶联受体（GPCR），已发现脱敏为 由受体-G蛋白解偶联，受体内在化和 受体下调。 我们将检验以下假设 关于对CT响应脱敏的机制。 推定的羧基末端中的氨基酸残基和第三 CT受体介导受体-G蛋白的细胞内环 解偶联，受体内在化和受体下调，这 部分通过刺激受体降解而发生。 测试这个 假设，我们将追求以下具体目的：1）设计和 为CT受体构造合成基因。 这个目标何时 成就将对该领域的研究产生重大实际影响 因为它将大大促进该受体的研究 分子遗传技术。 2）建立用 转染的CT受体cDNA显示刺激和脱敏 AC和磷酸和磷酸特异性磷脂酶C（PPLASE）， 受体内在化和受体下调。 3）确定 与G相互作用的CT受体的结构特征 蛋白质激活AC和PPLASE。 4）确定结构 CT受体的特征，介导受体-G蛋白解偶联， 以及受体内在化和下调。 分子遗传学 将用于构建合成基因并突变受体 DNA。 脱敏（或速度），这限制了大小和 响应的持续时间限制了通过起作用的药物的功效 这些受体。 因此，了解 脱敏的机制是能够设计非肽药物， 这不需要肠胃外和鼻内管理 可能避免脱敏。 这些药物可以增强功效 通过抑制脱敏或成为激动剂，受体激动剂 自己的CT-R。 这些代理可以用来治疗 骨质疏松症。