MECHANISMS OF HORMONE RELEASE BY ENDOCRINE CELLS

内分泌细胞释放激素的机制

• 批准号: 2448425
• 负责人: GIULIA BALDINI
• 金额: $ 18.06万
• 依托单位: COLUMBIA UNIVERSITY HEALTH SCIENCES
• 依托单位国家: 美国
• 财政年份: 1998
• 资助国家: 美国
• 起止时间: 1998-04-01 至 2001-12-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/2448425
• 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

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.

该建议的长期目标是研究细胞生物学 内分泌细胞的激素分泌。 分泌的att-20细胞 肾上腺皮质激素激素（ACTH）是一个很好的特征 调节分泌的细胞模型。 Rab蛋白是一类 小型GTP-ass似乎是囊泡交通的关键调节器。 一个 Rabs家族，Rab3同工型，与受监管 胞吐途径。 每个Rab3同工型可能在不同的 ACTH分泌途径的阶段。 了解分布 ATT-20细胞中不同RAB3蛋白的不同将有助于 鉴定生物发生和成熟的不同步骤 密集的核心颗粒。 att-20细胞同时表达rab3a和rab3d 位于不同的细胞室中。 第一个目的 建议是确定rab3d和rab3a在ACTH中的定位 细胞分馏和电子显微镜技术的途径。 在 表达突变的Rab3d N135i的ATT-20细胞，含ACTH的颗粒 能够位于质膜附近并受到调节 胞吞作用。 在表达突变的细胞中形成的致密核颗粒 Rab3d可能在成熟的早期阶段被阻止 其发布所需的基本组件。 第二个目标 该建议是确定这些组件。 Rab蛋白班车在 在GTP结合，活化构象和GDP结合之间 形式。 rab3d n135i大概被锁定在一个刚性构象中，可以 隔离A蛋白（Rab3D结合蛋白），该蛋白充当 Rab3d的下游效应子。 另一个可能性是突变的rab3d 耗尽了调节Rab3结合的Rab3蛋白活性的因子 到膜。 该提案的第三个目的是确定和 特征这些因素。内分泌疾病，例如糖尿病 I型和库欣疾病分别是由于缺乏菊粉 并增加了ACTH激素浓度到血液中。 长期 该建议的一项目标是帮助了解细胞如何分泌 激素以受管制的方式设定新颖的治疗方法 对于内分泌疾病的患者。