REGULATION OF ALS AND ITS ROLE IN THE IGF SYSTEM

长期目标是了解 胰岛素样生长因子系统。 IGF系统是必不可少的 正常的生长和发育。 各种缺陷 已经在癌症中鉴定了IGF系统的组分， 糖尿病和营养不良。 除了经典的相互作用 与受体，IGF-I和IGF-II的IGF系统的配体 与六种称为胰岛素样生长的可溶性载体蛋白相关联 因子结合蛋白（IGFBP 1 -6）。 出生后，功能性IGF 转运单位实际上是一个三元复合物， IGF与IGFBP-3和第三种蛋白质的关联， 酸不稳定亚基（ALS）。 此次申请的重点是ALS 因为目前的证据表明，ALS决定了血清 IGF-I和IGF-II水平及其向靶组织的递送。 增长 激素是控制ALS循环水平的主要因素。 然而，这种调节的机制并没有 被定义。 这一建议涉及增长的性质 ALS激素调节及其在体内的作用 具体目标 和方法是： 1. 为了确定生长激素 调节小鼠肝脏中ALS mRNA的丰度。 这 将通过比较肝脏中ALS mRNA的丰度来完成， 以及在不同生长条件下该基因的转录速率 激素状态 2. 为了定义在5'上游区的顺式元件， ALS基因介导生长激素和基础激活 转录。 这将是通过向肝细胞内注射 由ALS基因的启动子驱动的荧光素酶小基因。 3.研究ALS蛋白在体内的功能。 这将是 通过获得和研究ALS蛋白的小鼠， 无托叶 这些小鼠将通过基因敲除 approach.

The long term objective is to understand the physiology of the insulin-like growth factor system. The IGF system is essential to normal growth and development. Defects in the various components of the IGF system have been identified in cancer, diabetes and undernutrition. In addition to the classical interaction with receptors, IGF-I and IGF-II the ligands of the IGF system associate with six soluble carrier proteins called insulin-like growth factor binding protein (IGFBP1-6). Postnatally, the functional IGF transporting unit is actually a ternary complex formed by association of IGF with IGFBP-3 and a third protein called acid-labile subunit (ALS). The focus of this application is on ALS because current evidence suggests that ALS determines surum levels of IGF-I and -II and their delivery to target tissue. Growth hormone is a major factor controlling the circulating levels of ALS. The mechanisms underlying this regulation, however, have not been defined. This proposal addresses the nature of growth hormone regulation of ALS and its role in vivo. The specific aims and methods are: 1. To determine themechanism by which growth hormone regulates the abundance of ALS mRNA in the liver of mice. This will be done by comparing in liver the abundance of ALS mRNA and the rate of transcription of the gene under different growth hormone status. 2. To define the cis-elements in the 5' upstream region of the ALS gene that mediate the growth hormone and basal activation of transcription. This will be done by transfecting into liver cells luciferase minigenes driven by the promoter of the ALS gene. 3. To study the fuction of the ALS protein in vivo. This will be done by obtaineng and studying mice in which the ALS protein is absent. These mice iwll be created by the gene knockout approach.