REGULATION OF EGF RECEPTORS BY CALCIOTROPIC HORMONES

描述(改编自申请者摘要)：这是一个新的 申请一等奖，建议研究EGF的监管 甲状旁腺素、骨化三醇、骨化三醇对UMR大鼠成骨样细胞受体表达的影响 维甲酸。初步数据显示甲状旁腺素和骨化三醇增加 UMR细胞中的EGF结合和反应，这种效应似乎是 由于EGF受体数量的增加而不是结合的变化 亲和力。Northern印迹和核糖核酸酶保护实验的进一步分析 证明两种药物都能诱导稳态EGF受体的增加 信使核糖核酸水平提高3到5倍。使用EGF受体启动子的初步数据 与荧光素酶报告基因相连的结构表明，这些 影响很可能是转录性质的。单独的维甲酸也是如此 增加EGF结合，但减弱甲状旁腺素和骨化三醇对EGF的影响 有约束力的。假设甲状旁腺素、骨化三醇和维甲酸 增加EGF受体的转录速率，即维甲酸 干扰甲状旁腺素刺激的cAMP的产生，而维甲酸 调节维生素D对5‘侧翼VDRE的影响 EGF受体基因的区域。目前的提案将在更多方面进行探索 促钙激素对表皮生长因子影响的分子基础 受体表达。具体目标是：1)确定机制 甲状旁腺激素、骨化三醇和 维甲酸；2)鉴定EGF受体启动子中 负责甲状旁腺素、骨化三醇和维甲酸对 3)确定骨化三醇与骨化三醇相互作用的机制。 4)研究维甲酸的相互作用机制。 维甲酸和甲状旁腺素。

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.