MECHANISM OF IGF-I EFFECTS ON CHROMAFFIN CELL FUNCTION

据报道，胰岛素样生长因子-I（IGF-I）作为营养因子， 增强与分化相关的功能的因素 许多细胞的表型。 通常IGF-I似乎调节 对增殖几乎没有或没有影响的细胞。 肾上腺 嗜铬细胞，IGF-I增强促分泌素刺激的儿茶酚胺 分泌和Ca 2+摄取到细胞中。 长期目标是 本课题旨在阐明IGF-I发挥其营养作用的机制， 影响细胞功能。 本补助金中描述的研究将 研究长期暴露于IGF-I增强 促分泌素刺激嗜铬细胞分泌儿茶酚胺。 我们 将检验IGF-I通过激活一种 蛋白激酶C的同工酶。 蛋白质作用的一般性 激酶C在IGF-I作用中的作用将使用IGF-I对 肾上腺皮质细胞类固醇生成作为另一个模型系统。 因为 儿茶酚胺是重要的激素和神经递质， 外周和中枢神经系统，这项工作将增加我们的 不仅了解嗜铬细胞功能的调节， 也是这些过程的调节，如血压和 心血管功能，这是由儿茶酚胺调节。 在 此外，了解IGF-I的营养作用，如 类固醇生成 本研究的具体目的是：1.到 确定蛋白激酶C是否需要IGF-I增强 嗜铬细胞分泌的儿茶酚胺。 细胞中的蛋白质 激酶C活性被抑制剂或下调抑制 将用于确定蛋白激酶C是否参与IGF-I 行动上2.为了确定蛋白激酶C是如何参与 IGF-I对嗜铬细胞分泌的影响。 IGF-I对人乳腺癌细胞的影响 蛋白激酶C的活性，以及佛波酯和蛋白质的作用 将检查激酶C抑制剂对IGF-I受体功能的影响。3. 为了确定IGF-I对蛋白激酶C的作用是否是负责 IGF-I处理的嗜铬细胞中Ca 2+摄取增强，并确定 这种作用是否会导致IGF-I治疗的分泌增加， 细胞Ca 2+摄取和流出实验将在未处理的 IGF-1处理的细胞使蛋白激酶C活性缺乏。4.到 确定蛋白激酶C是否参与IGF-I对 促肾上腺皮质激素刺激肾上腺皮质cAMP的积累和皮质醇的合成 细胞 蛋白激酶C活性降低的肾上腺皮质细胞 通过抑制剂或下调抑制的基因将被用于 确定蛋白激酶C是否参与IGF-I的作用， 细胞

Insulin-like growth factor-I (IGF-I) has been reported to act as a trophic factor which enhances functions associated with the differentiated phenotype of many cells. Often IGF-I appears to modulate the activity of the cells with little, or no, effect on proliferation. In adrenal chromaffin cells, IGF-I enhances secretagogue-stimulated catecholamine secretion and Ca2+ uptake into the cells. The long-term objective of this project is to elucidate the mechanism by which IGF-I exerts its trophic effects on cell function. The studies described in this grant will investigate the mechanism by which chronic exposure to IGF-I enhances secretagogue-stimulated catecholamine secretion from chromaffin cells. We will examine the hypothesis that IGF-I enhances secretion by activating one of the isozymes of protein kinase C. The generality of the role of protein kinase C in IGF-I action will be explored using the effect of IGF-I on steroidogenesis in adrenocortical cells as another model system. Because catecholamines are important as hormones and neurotransmitters in the peripheral and central nervous system, this work will increase our understanding not only of the regulation of chromaffin cell function, but also of the regulation of those processes, such as blood pressure and cardiovascular function, that are regulated by catecholamines. In addition, understanding the trophic effects of IGF-I, such as steroidogenesis. The specific aims of the proposed research are: 1. To determine whether protein kinase C is required for IGF-I enhanced catecholamine secretion from chromaffin cells. Cells in which protein kinase C activity is suppressed either by inhibitors or by down regulation will be used to determine whether protein kinase C is involved in IGF-I action. 2. To determine how protein kinase C is involved in the effect of IGF-I on secretion from chromaffin cells. The effect of IGF-I on the activity of protein kinase C, and the effect of phorbol esters and protein kinase C inhibitors on the function of IGF-I receptors will be examined. 3. To determine whether the effect of IGF-I on protein kinase C is responsible for enhanced Ca2+ uptake in IGF-I treated chromaffin cells and to determine whether such an effect causes the enhanced secretion seen in IGF-I treated cells. Ca2+ uptake and efflux experiments will be performed in untreated and IGF-I treated cells made deficient in protein kinase C activity. 4. To determine whether protein kinase C is involved in the effect of IGF-I on ACTH stimulated cAMP accumulation and cortisol synthesis in adrenocortical cells. Adrenocortical cells in which protein kinase C activity is suppressed either by inhibitors or by down regulation will be used to determine whether protein kinase C is involved in IGF-I action in these cells.