BIOCHEMISTRY AND GENETICS OF VITAMIN D RECEPTOR ACTIONS

描述(摘自申请者摘要)：维生素D受体 (VDR)以异二聚体的形式与维生素D反应元件(VDRE)结合 与维甲酸X受体(RXR)的复合体，并介导 1，25-二羟基维生素D3[1，25(OH)2D3]对基因表达的影响。它是 公认的是额外的核蛋白，称为受体或 核辅助因子，是高亲和力结合所必需的 VDRE。首席调查员使用酵母双杂交系统进行克隆 编码VDR相互作用蛋白的cDNA，其中两个在没有 1，25(OH)2D3和9在1，25(OH)2D3存在的情况下。她假设 从酵母双杂交系统中获得维生素D相互作用蛋白 是1，25(OH)2D3介导的基因调控的转录因子。在……里面 支持这一假说，她发现其中之一，人类类固醇 受体共激活因子-1(SRC-1)，已知的其他基因的转录因子 类固醇激素以配体依赖的方式与VDR相互作用，如 表现为(-半乳糖苷酶的产生。VDR和SRC-1 Take的相互作用 放置在生理浓度的1，25(OH)2D3。缺失-突变 对VDR的分析确定了配体依赖的激活结构域 受体(AF-2)是与SRC-1相互作用所必需的，并且 SRC-1的缺失-突变分析表明，27个氨基酸是 与VDR交互所需。此外，反义研究表明 SRC-1是刺激碱性磷酸酶产生所必需的 人骨肉瘤细胞对1，25(OH)2D3的反应校长 研究人员建议将这些研究扩展到调查是否和 SRC-1和其他推定因子在多大程度上参与了1，25(OH)2D3 介导的基因调控。预测的结果将提供重要的 1，25(OH)2D3介导效应的分子生物学新信息 关于细胞功能。

DESCRIPTION (Adapted from the Applicant's Abstract): The vitamin D receptor (VDR) binds to the vitamin D response element (VDRE) as a heterodimeric complex with the retinoid X receptor (RXR) and mediates the effects of 1,25-dihydroxyvitamin D3 [1,25(OH)2D3] on gene expression. It is well-established that additional nuclear proteins, termed receptor or nuclear auxiliary factors, are required for high affinity binding to the VDREs. The principal investigator used a yeast two-hybrid system to clone cDNAs which code for VDR-interacting proteins, two of them in the absence of 1,25(OH)2D3 and nine in the presence of 1,25(OH)2D3. She hypothesizes that the vitamin D interacting proteins obtained from the yeast two-hybrid system are transcription factors for 1,25(OH)2D3 mediated gene regulation. In support of this hypothesis, she found that one of them, human steroid receptor coactivator-1 (SRC-1), a known transcription factor for other steroid hormones, interacts with the VDR in a ligand-dependent manner as shown by (-galactosidase production. Interaction of VDR and SRC-1 takes place at physiologic concentrations of 1,25(OH)2D3. Deletion-mutation analysis of the VDR established that the ligand-dependent activation domain (AF-2) of the receptor is required for interaction with SRC-1 and deletion-mutation analysis of SRC-1 demonstrated that 27 amino acids are required for interaction with the VDR. Further, antisense studies indicate that SRC-1 is required for stimulation of alkaline phosphatase production by human osteosarcoma cells in response to 1,25(OH)2D3. The principal investigator proposes to extend these studies to investigate whether and to what extent SRC-1 and other putative factors are involved in 1,25(OH)2D3 mediated gene regulation. The results are predicted to provide important new information about the molecular biology of 1,25(OH)2D3-mediated effects on cellular function.