REGULATION OF EGF RECEPTORS BY CALCIOTROPIC HORMONES

描述（改编自申请人的摘要）：这是一个新的 申请第一个奖项，建议研究EGF的调节 通过PTH、骨化三醇和 视黄酸 初步数据表明，PTH和骨化三醇增加， EGF在UMR细胞中的结合和反应，这种作用似乎是 这是由于EGF受体数量的增加，而不是结合的变化。 亲和力 用北方印迹和RNA酶保护试验进行进一步分析 表明两种药物均诱导稳态EGF受体增加， mRNA水平增加3至5倍。 使用EGF受体启动子的初步数据 与荧光素酶报告基因连接的构建体表明，这些 影响可能是转录性质的。 单独的视黄酸也 增加EGF结合，但钝化PTH和骨化三醇对EGF的作用 约束力 假设PTH、骨化三醇和视黄酸均 增加EGF受体的转录速率， 干扰PTH刺激的cAMP产生， 调节维生素D对5'侧翼中推定的VDRE的影响 EGF受体基因 目前的提案将探讨更多 详细说明钙激素对EGF的影响的分子基础 受体表达 具体目的是：1）确定机理 EGF受体mRNA的增加对PTH，骨化三醇， 视黄酸; 2）鉴定EGF受体启动子中的区域， 负责PTH、骨化三醇和视黄酸对 转录; 3）确定骨化三醇与 4）探讨了维生素A酸与维生素A的相互作用机制。 维甲酸和PTH。

DESCRIPTION (Adapted from the Applicant's Abstract): This is a new application for a FIRST Award which proposes to study the regulation of EGF receptor expression in UMR rat osteoblast-like cells by PTH, calcitriol, and retinoic acid. Preliminary data indicates that PTH and calcitriol increase EGF binding and responses in UMR cells, and that this effect appears to be due to an increase in EGF receptor number rather than a change in binding affinity. Further analyses with Northern blot and RNase protection assays demonstrate that both agents induce an increase in steady state EGF receptor mRNA levels by 3 to 5-fold. Preliminary data using EGF receptor promoter constructs linked to a luciferase reporter gene demonstrate that these effects are likely transcriptional in nature. Retinoic acid alone also increased EGF binding, but blunted the effects of PTH and calcitriol on EGF binding. The hypotheses are that PTH, calcitriol, and retinoic acid all increase transcriptional rates of the EGF receptor, that retinoic acid interferes with PTH-stimulated cAMP production, and that retinoic acid modulates the effects of vitamin D on a putative VDRE in the 5' flanking region of the EGF receptor gene. The current proposal will explore in more detail the molecular basis of the effects of calciotropic hormones on EGF receptor expression. The Specific Aims are: 1) to determine the mechanism for the increase in EGF receptor mRNA in response to PTH, calcitriol, and retinoic acid; 2) to identify the regions in the EGF receptor promoter which are responsible for the actions of PTH, calcitriol, and retinoic acid on transcription; 3) to define the mechanism of interaction of calcitriol with retinoic acid; and 4) to investigate the mechanism of interaction of retinoic acid and PTH.