MECHANISMS OF HORMONE RELEASE BY ENDOCRINE CELLS

内分泌细胞释放激素的机制

基本信息

批准号：
6342505
负责人：
GIULIA BALDINI
金额：
$ 20.78万
依托单位：
COLUMBIA UNIVERSITY HEALTH SCIENCES
依托单位国家：
美国
项目类别：
财政年份：
1998
资助国家：
美国
起止时间：
1998-04-01 至 2003-03-31
项目状态：
已结题

来源：
https://reporter.nih.gov/project-details/6342505
关键词：
adrenocorticotropic hormone binding proteins cell fusion density density gradient ultracentrifugation exocytosis granule hormone biosynthesis hormone regulation /control mechanism immunoelectron microscopy membrane proteins peptide hormone biosynthesis protein binding protein isoforms secretion tissue /cell culture transfection yeast two hybrid system

项目摘要

The long term objective of this proposal is to study the cell biology of hormone secretion by endocrine cells. AtT-20 cells, which secrete adrenocorticotropic hormone (ACTH) are a very well characterized cellular model for regulated secretion. Rab proteins are a class of small GTP-ases that seem to be key regulators of vesicular traffic. A family of Rabs, the Rab3 isoforms, associate with the regulated exocytotic pathway. Each Rab3 isoform may be associated at different stages of the ACTH secretory pathway. Understanding the distribution of different Rab3 proteins in AtT-20 cells will help in the identification of different steps in the biogenesis and maturation of dense core granules. AtT-20 cells express both Rab3A and Rab3D which are localized in different cellular compartments. The first aim of this proposal is to determine the localization of Rab3D and Rab3A in the ACTH pathway by cell fractionation and electron microscopy techniques. In AtT-20 cells expressing mutated Rab3D N135I, ACTH-containing granules are able to position near the plasma membrane and to undergo regulated exocytosis. Dense core granules formed in cells expressing mutated Rab3D may be blocked at an early stage of maturation and lack fundamental components necessary for their release. The second aim of this proposal is to identify these components. Rab proteins shuttle in between a GTP-bound, activated conformation and a GDP-bound, inactive form. Rab3D N135I is presumably locked in one rigid conformation and may sequester a protein (Rab3D-binding protein) which functions as a downstream effector of Rab3D. Another possibility is that mutated Rab3D depletes factors which modulate Rab3 protein activity of Rab3 binding to membranes. The third aim of this proposal is to identify and characterize these factors. Endocrine diseases such as Diabetes Mellitus type I and Cushing Disease are due, respectively, to a lack of inulin and increased concentrations of ACTH hormone into the blood. The long- term goal of this proposal is to help understanding how cells secrete hormones in a regulated fashion and to set novel therapeutic approaches for patients with endocrine diseases.

该提案的长期目标是研究细胞生物学内分泌细胞分泌激素。 AtT-20 细胞，分泌促肾上腺皮质激素（ACTH）是一种非常明确的特征调节分泌的细胞模型。 Rab 蛋白是一类小 GTP 酶似乎是囊泡交通的关键调节因子。一个 Rabs 家族，即 Rab3 亚型，与受监管的胞吐途径。每个 Rab3 同种型可能与不同的位点相关联 ACTH 分泌途径的各个阶段。了解分布 AtT-20 细胞中的不同 Rab3 蛋白将有助于鉴定生物发生和成熟的不同步骤致密的核心颗粒。 AtT-20 细胞同时表达 Rab3A 和 Rab3D，位于不同的细胞区室中。本次活动的第一个目的建议确定 Rab3D 和 Rab3A 在 ACTH 中的定位通过细胞分级分离和电子显微镜技术的途径。在 AtT-20 细胞表达突变的 Rab3D N135I、含 ACTH 的颗粒能够定位在质膜附近并接受调节胞吐作用。表达突变的细胞中形成致密核心颗粒 Rab3D 可能在成熟的早期阶段被阻断并且缺乏其释放所必需的基本组件。第二个目标是该提案旨在确定这些组成部分。 Rab 蛋白穿梭于 GTP 结合的激活构象和 GDP 结合的非活性构象之间形式。 Rab3D N135I 可能被锁定在一种刚性构象中，并且可能隔离一种蛋白质（Rab3D 结合蛋白），其功能为 Rab3D 的下游效应器。另一种可能性是 Rab3D 突变消耗调节 Rab3 蛋白结合活性的因子到膜。该提案的第三个目标是确定并描述这些因素的特征。内分泌疾病，如糖尿病 I 型和库欣病分别是由于缺乏菊粉血液中 ACTH 激素的浓度增加。长- 该提案的长期目标是帮助理解细胞如何分泌以受监管的方式调节激素并制定新的治疗方法对于内分泌疾病患者。