MECHANISM OF NON-GENOMIC ACTION OF VITAMIN D

描述（改编自研究者摘要）：不再有 维生素D代谢物1 α，25- 二羟维生素D3（1 α，25-（OH）2D 3，骨化三醇或CT）及其 代谢和合成类似物表现出非基因组作用。迅速 新出现的证据表明，非基因组作用起着重要的作用， 在控制导致许多疾病的机制方面的作用 来自钙稳态的紊乱（例如，骨质疏松症），细胞 生长（乳腺癌，银屑病），细胞分化和免疫 （可能是艾滋病）。最近出现的非钙离子，合成 类似物已经迎来了治疗用途的现实可能性， 这些合成剂用于治疗上述疾病。 1alpha，25- （OH）2D 3是刺激急性，短暂的增加， 细胞内游离钙浓度（[Ca 2 +]I）和伴随的 肌醇多磷酸的生产。 这些是第一个可测量的 在细胞暴露于这些物质的一分钟内发生的表现， 剂.这些作用与细胞膜（细胞表面）的作用非常相似 受体激动剂介导的机制。然而，精确的机制 维生素D类似物诱导[Ca 2 +]I急性变化的机制是 未知申请人最近的数据表明， 受体（VDR）结合质膜（PM）和内质网 网织膜（ER）。此外，ER组分中的钙网蛋白（CRT）是 VDR的特异性接受蛋白。因为这两层膜 构成了[Ca 2 +]I控制的主要位点， VDR与细胞膜的相互作用及其在[Ca 2 +]I中的作用 控制必须明确。细胞生物学的最新进展（转染 技术），合成具有不同生物活性的维生素D类似物， 与钙通量测量相关的性能和技术 在活细胞中，以及在孤立的膜囊泡中， 可以从逻辑上研究手头的问题。 因此 本研究的具体目的是：1）分析相互作用 的VDR与ER，以阐明VDR/CT的作用 的相互作用对钙释放的ER和确定的功能 CRT对细胞内钙库的调节作用; 2）研究CRT对细胞内钙库的调节作用。 VDR与PM的相互作用，以阐明 在CT刺激的急性Ca 2+内流中的这种相互作用，并确定 VDR的PM特异性接受蛋白。

DESCRIPTION (Adapted from investigator's abstract): There no longer appears to be any question that the vitamin D metabolite, 1alpha,25- dihydroxyvitamin D3 (1alpha,25-(OH)2D3, calcitriol or CT), and its metabolic and synthetic analogs manifest nongenomic actions. Rapidly emerging evidence indicates that the nongenomic action plays important roles in controlling the mechanisms that underlie many diseases arising from disturbances in calcium homeostasis (e.g., osteoporosis), cell growth (breast carcinoma, psoriasis), cell differentiation and immune responses (possibly AIDS). The recent advent of noncalcemic, synthetic analogs has ushered in the realistic possibility of therapeutic use of these synthetic agents for the treatment of the above-mentioned diseases. The most prominent evidence for the nongenomic action of 1alpha,25- (OH)2D3 is stimulation of an acute, transient increase in the intracellular free calcium concentration ([Ca2+]I) and concomitant production of inositol polyphosphates. These are the first measurable manifestations that occur within one minute of cellular exposure to the agents. These actions closely resemble those of membrane (cell surface) receptor-agonist mediated mechanisms. However, the precise mechanisms by which vitamin D analogs induce the acute change in [Ca2+]I are unknown. The applicants' recent data demonstrate that the vitamin D receptor (VDR) binds to both plasma membrane (PM) and endoplasmic reticulum (ER). Furthermore, calreticulin (CRT) in the ER fraction is a specific acceptance protein for VDR. Since these two membranes constitute the major sites of [Ca2+]I control, the interaction between VDR and the membranes, and the role of the interaction in [Ca2+]I control must be clarified. Recent advances in cell biology (transfection technology), synthesis of vitamin D analogs with different biological properties and technologies related to the measurement of calcium fluxes in living cells, as well as in isolated membrane vesicles, make it now possible to logically investigate the problems at hand. Therefore, the Specific Aims of the proposed studies are to: 1) analyze the interaction of the VDR with the ER in order to elucidate the role of VDR/CT interaction on Ca2+ release from the ER and to determine the function of CRT in regulating intracellular Ca2+ stores; and 2) study the interaction of the VDR with the PM in order to elucidate the role of this interaction in acute Ca2+ influx stimulated by CT, and to identify a PM-specific acceptance protein for VDR.