VITAMIN D-REGULATED EXOCYTOSIS IN OSTEOBLASTS

成骨细胞中维生素 D 调节的胞吐作用

• 批准号: 7031642
• 负责人: LAURA P ZANELLO
• 金额: $ 20.64万
• 依托单位: UNIVERSITY OF CALIFORNIA RIVERSIDE
• 依托单位国家: 美国
• 财政年份: 2005
• 资助国家: 美国
• 起止时间: 2005-04-01 至 2008-03-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7031642
• 关键词: 1,25 dihydroxycholecalciferol; biological signal transduction; chloride channels; confocal scanning microscopy; exocytosis; gene induction /repression; genetically modified animals; hormone regulation /control mechanism; immunocytochemistry; laboratory mouse; osteoblasts; osteogenesis; protein localization; vitamin D receptors; voltage /patch clamp; voltage gated channel

DESCRIPTION (provided by applicant): The steroid 1alpha,25(OH)2 vitamin D3 (1,25D) is a systemic hormone with bone anabolic effects. 1,25D promotes the synthesis of bone matrix and its mineralization by acting on osteoblasts. This occurs via interaction with the vitamin D receptor (VDR) and modulation of gene transcription. In addition, 1,25D acts rapidly (sec-min) at the plasma membrane level, where it activates cytoplasmic signaling pathways and ion channel functions. I recently demonstrated that 1,25D-potentiation of chloride currents is coupled to a stimulation of secretion of matrix proteins in osteoblasts expressing a functional VDR. However, the precise molecular mechanisms of these 1,25D effects remain only partially understood. The long-term goal of this proposal is to elucidate 1,25D non-genomic mechanisms of bone formation in osteoblasts. My working hypothesis, which I propose as a new investigator, is that signal transduction triggered by 1,25D acting at a membrane-associated VDR leads to a non-genomic rapid exocytotic response, which is coupled to chloride channel activation in osteoblasts. This explains in part the anabolic effects of the hormone in bone. The first specific aim of this proposal investigates two parallel signal transduction pathways recruited by a membrane-associated VDR in osteoblasts: a) Galpha q/cAMP/PKA/CI- channel phosphorylation/exocytosis, and b) Galpha q/PLC/IP3/calcium/exocytosis. The second specific aim studies the osteoblastic CIC-3 gene, its protein product, and coupling to exocytosis. This will be studied in osteoblasts obtained from VDR WT and KO mice, the latter expressing a rachitic phenotype. Although the primary focus of this proposal is on basic research, the objective is to identify molecular targets in the treatment of bone pathologies characterized by decreased bone mass and mineralization. This typifies skeletal diseases such as osteoporosis and osteomalacia, respectively. Osteoporosis in particular affects a large sector of the aging American population and constitutes a significant economic burden.

描述（由申请人提供）：类固醇1 α，25(OH)2维生素D3 （1,25 d）是一种具有骨合成代谢作用的全身性激素。1,25 d通过作用于成骨细胞促进骨基质的合成及其矿化。这是通过与维生素D受体（VDR）的相互作用和基因转录的调节而发生的。此外，1,25 d在质膜水平上作用迅速（秒-分钟），激活细胞质信号通路和离子通道功能。我最近证明，氯离子电流的1,25 d增强与表达功能性VDR的成骨细胞中基质蛋白分泌的刺激相结合。然而，这些125d效应的精确分子机制仍然只是部分被理解。本研究的长期目标是阐明成骨细胞成骨的1,25d非基因组机制。作为一名新的研究者，我提出了我的工作假设，即由1,25 d作用于膜相关VDR触发的信号转导导致非基因组快速胞外反应，这与成骨细胞中的氯离子通道激活相耦合。这在一定程度上解释了这种激素在骨骼中的合成代谢作用。本研究的第一个具体目的是研究成骨细胞中膜相关VDR募集的两个平行信号转导途径：a) Galpha q/cAMP/PKA/CI-通道磷酸化/胞吐，b) Galpha q/PLC/IP3/钙/胞吐。第二个具体目的是研究成骨细胞CIC-3基因、其蛋白产物及其与胞吐作用的偶联。这将在从VDR WT和KO小鼠中获得的成骨细胞中进行研究，后者表达佝偻病表型。虽然本提案的主要重点是基础研究，但目的是确定以骨量减少和矿化为特征的骨病理治疗的分子靶点。这分别代表了骨质疏松症和骨软化症等骨骼疾病。骨质疏松症尤其影响到美国老龄人口的很大一部分，并构成了一个重大的经济负担。