1,25-DIHYDROXYVITAMIN D RECEPTOR/FUNCTION IN NEW TARGETS

本项目的总体目标是阐明功能（S） 1，25-二羟基维生素D3（1，25（OH）2D 3），或其缺乏， 新的假定靶组织，通过解决假设， 1，25（OH）2D 3通过以下途径发挥特定和重要的作用： 之前描述的受体。 因此，1，25（OH）2D 3的功能将 通过一系列的生理和 模型系统大鼠心脏和睾丸中的生化标准。 这些研究的第一阶段集中在测试 1，25（OH）2D 3在细胞内钙离子通道中起作用的假说 体内平衡 然而，由于限制这种错误， 研究任何一个领域的可能功能，假设， 1，25（OH）2D 3通过替代机制影响这些系统， 在未来进行测试。 之间是否存在相关性 维生素D状态或1，25（OH）2D 3受体与生理功能 将通过评估维生素D状态对 对正常钙大鼠心肌收缩特性的影响 以及睾丸功能，并检查1，25（OH）2D 3 假定的新靶组织中的受体水平与 维生素D内分泌系统的生理状态。 影响 1，25（OH）2D 3状态和受体对细胞内钙的影响 心脏和Sertoli细胞中的稳态将通过 研究了激素对正常人摄取~（45）Ca的影响， 培养的心肌细胞和Sertoli细胞。 1，25（OH）2D 3的作用 对选定机制/亚细胞器的影响将通过 测定心肌细胞和Sertoli细胞的45 Ca摄取， 不存在和存在药理学探针。 其他研究 将扩展1，25（OH）2D 3状态/受体影响的研究 通过45 CA与蛋白质结合检测钙结合蛋白 transblotted印迹to nitrocellulose硝酸纤维素membranes膜，on proteins蛋白modulated调制by 钙调蛋白125-I-钙调蛋白凝胶覆盖技术， 钙结合蛋白的免疫细胞化学定位， 证明维生素D调节。 这些相互关联的研究 1，25（OH）2D 3功能和受体在推定的新目标将增加 对我们了解维生素D内分泌系统有很大帮助， 将为未来评估1，25（OH）2D 3功能提供基础 在正常和患病的个体中。

The overall goal of this project is to elucidate the function(s) of 1,25-dihydroxyvitamin D3(1,25(OH)2D3), or the lack thereof, in new putative target tissues by addressing the hypothesis that 1,25(OH)2D3, exerts specific and important effects therein via previously described receptors. Thus, 1,25(OH)2D3 function will be rigorously evaluated by a series of physiological and biochemical criteria in the model systems rat heart and testis. The first phases of these studies are focused on testing the hypothesis that 1,25(OH)2D3 plays a role in intracellular calcium homeostasis. However, because of the fallacy in limiting such studies to any one area of possible functions, the hypothesis that 1,25(OH)2D3 affects these systems through alternate mechanisms must be tested in the future. Whether there is a correlation between vitamin D status or 1,25(OH)2D3 receptor and physiological function will be tested by evaluating the effects of vitamin D status in normocalcemic rats on the contractile properties of heart muscles and on testicular function and examining whether 1,25(OH)2D3 receptor levels in putative new target tissues correlate with physiological status of the vitamin D endocrine system. Effects of 1,25(OH)2D3 status and receptors on intracellular calcium homeostasis in heart and Sertoli cells will be evaluated by studying the hormonal effects on uptake of 45Ca into intact cultured heart myocytes and Sertoli cells. Effects of 1,25(OH)2D3 on selected mechanisms/subcellular organelles will be evaluated by determining 45Ca uptake in heart myocytes and Sertoli cells in the absence and presence of pharmacological probes. Additional studies will extend studies of the effects of 1,25(OH)2D3 status/receptors on calcium binding proteins detected by 45CA binding to proteins transblotted to nitrocellulose membranes, on proteins modulated by calmodulin by the 125-I-calmodulin gel overlay technique, and by immunocytochemical localization of calcium binding proteins that demonstrate vitamin D regulation. These interrelated studies of 1,25(OH)2D3 function and receptors in putative new targets will add much to our understanding of the vitamin D endocrine system and will provide a basis for future assessments of 1,25(OH)2D3 function in both normal and diseased individuals.