CELLULAR INTERACTIONS OF LEAD, CALCIUM, AND ZINC

铅中毒仍然是可预防的主要健康问题之一。 儿童在这个国家的危害。美国政府最近的估计。 公共卫生部门表示，有三到四个人 数百万儿童面临铅对健康不利影响的风险 (ATSDR，1988)。铅和必需物质之间复杂的相互作用 元素，主要是钙、铁、锌和铜，在 临床和实验文献。机制和 这些相互作用的毒理学意义尚不清楚。 明白了。本申请的目的是阐明 铅对激素信号转导过程的影响。这 竞争续期申请继续调查 Pb2+-Ca2+相互作用的细胞生物学研究进展 阐明Pb2+在细胞周期调控中的分子作用部位 骨钙素基因。这些实验一起测试了 铅毒性是通过一种扰动表达的假说 钙信使系统和锌介导的细胞功能。这个 这项建议的具体目标是： 1.研究铅对神经细胞动员的影响 [Ca~(2+)]i由第二信使肌醇1，4，5-tris- 通透性ROS细胞中的磷酸或花生四烯酸。 实验将使用45Ca和ION 选择性电极，以深入了解 Pb2+对第二信使功能的影响。 2.调查第二信使的能力，Myo- 肌醇、1，4，5-三磷酸和花生四烯酸 从ROS细胞的胞内储备物中动员Pb2+。 将使用210Pb进行实验以获得洞察力 铅离子在信号转导过程中的动态变化 流程。 3.研究Pb2+对钙调蛋白和钙调素的影响 蛋白激酶C介导的功能。广谱 铅对钙调素和蛋白激酶C的影响 通过蛋白质的二维电泳法建立 磷酸化。Pb2+对人血清白蛋白的更特异作用 蛋白激酶C介导的功能将被建立 通过监测鸟氨酸的激素调节 脱羧酶。 4.阐明抑制细胞分裂的作用机制 1，25-二羟基维生素D3诱导大鼠骨钙素的表达 关注锌离子介导的成骨细胞 这一过程的各个方面。将进行实验 以(A)测定锌离子的置换和结合 1，25(OH)2D3受体锌指上的Pb2+，(B) 探讨铅对受体易位的影响 到细胞核，(C)受体与DNA结合，最后 (D)骨钙素的转录和翻译 吉恩。 该项目开发的概念和成果应 直接有助于了解老年人的骨骼代谢 铅，作为铅中毒目标的骨骼，以及 可能调动骨骼铅的生理因素。这个 定义铅的作用的细胞和分子概念 激素信号转导过程也应该广泛地 适用于理解铅对生长的影响， 高血压，以及行为和学习缺陷。

Lead toxicity continues to be one of the major preventable health hazards of children in this country. Recent estimates by the U.S. Department of Public Health indicate that between three and four million children are at risk for adverse health effects from lead (ATSDR, 1988). Complex interactions between lead and essential elements, primarily calcium, iron, zinc and copper are reported in the clinical and experimental literature. The mechanisms and toxicological significance of these interactions is not clearly understood. The objective of this application is to elucidate the effects of lead on hormone-signal transduction processes. This application for competitive renewal continues investigation into the cell biology of Pb2+-Ca2+ interactions, with new initiatives to elucidate the molecular site of action of Pb2+ on regulation of the osteocalcin gene. Together these experiments test the hypothesis that lead toxicity is expressed via a perturbation of the calcium messenger system and zinc-mediated cell functions. The specific aims of this proposal are to: 1. Investigate the effects of lead on the mobilization of [Ca2+]i by the second messengers myo-inositol 1,4,5-tris- phosphate or arachidonic acid in permeabilized ROS cells. Experiments will be conducted using 45Ca and ion selective electrodes to gain insight into the action of Pb2+ on second messenger function. 2. Investigate the ability of the second messengers, myo- inositol, 1,4,5-tris-phosphate and arachidonic acid to mobilize Pb2+ from intracellular stores in ROS cells. Experiments will be conducted using 210Pb to gain insight into the dynamic state of Pb+ during signal-transduction processes. 3. Characterize the effects of Pb2+ on calmodulin and protein kinase C-mediated functions. Broad spectrum effects of lead on calmodulin and protein kinase C will be established by 2-d electrophoretic analysis of protein phosphorylation. The a more specific action of Pb2+ on a protein kinase C-mediated function will be established by monitoring the hormonal regulation of ornithine decarboxylase. 4. Elucidate the mechanism of action by which inhibits the induction of osteocalcin by 1,25-dihydroxyvitamin D3 in osteoblastic bone cells focusing on the Zn2+-mediated aspects of this process. Experiments will be conducted to (a) determine the displacement of Zn2+ and binding of Pb2+ at the zinc-fingers of the 1,25(OH)2D3 receptor, (b) investigate the effects of lead on receptor translocation to the nucleus, (c) receptor binding to DNA, and finally (d) transcription and translation of the osteocalcin gene. The concepts and results developed by this project should contribute directly to understanding the skeletal metabolism of lead, the skeleton as a target of lead toxicity, and the physiological factors which may mobilize skeletal lead. The cellular and molecular concepts defining the actions of lead on hormone signal-transduction processes should also be broadly applicable to understanding the effects of lead on growth, hypertensin, and behavior and learning deficits.