Growth and Function of Cultured Gastrointestinal Muscle

描述（申请人摘要）：本提案的目的是 表征介导生长促进作用的信号通路 IGF-I和IGF-binding protein-5（IGFBP-5）的表达，以及生长抑制作用 TGF-β 1和IGFBP-1在人肠平滑肌细胞上的表达。的 实验方法利用正常人肠肌细胞， 在培养中的生长，其再现了肌肉组织在培养中的快速生长。 正在发育或发炎的肠道。先前的研究表明， 生长中的细胞产生的IGF-I和IGFBP-5在生长过程中是高的。 增殖期和下降的办法融合，而 TGF-β 1和IGFBP-3的水平在细胞达到汇合后最高。 本提案具体目标的基本假设是， 生长因子和结合蛋白激活刺激和抑制 调节以下的信号传导途径：（i）IGF-I受体的表达;（ii） 生长因子和结合蛋白的产生，以及它们 促进或抑制生长;和（iii）细胞周期从G 1到S阶段。具体目标是：（1）确定 IGF-I、TGF-β 1、IGFBP-5和IGFBP-3的IGF-I受体表达 （2）表征介导刺激性细胞凋亡的信号通路。 IGF-I和IGFBP-5的作用，以及TGF-β 1和IGFBP-3对 细胞生长以及生长因子和结合蛋白的产生;和（3） 识别调控细胞周期从G1期到S期进程的信号 相位每个具体目标都有大量的初步数据支持。IGF-I 和IGFBP-5通过调节其产生的相互途径连接， 生长促进作用和抑制IGF-I受体表达的能力。的 途径包括IGF-I激活p42/44 MAP激酶和PI 3-激酶 受体酪氨酸激酶，IGFBP-5受体激活p38 MAP激酶 丝氨酸激酶TGF-β 1和IGFBP-3激活TGF-β 1受体丝氨酸激酶 导致Smad 2磷酸化和IGF-I受体的抑制 磷酸化IGF-I刺激细胞周期蛋白D1表达、cdk 4活性和pRb 磷酸化，TGF-β 1刺激cdk抑制剂p15 INK 4 B。的 研究提供了一种细胞机制的分析， 肌肉生长的开始和停止。

DESCRIPTION (Applicant's Abstract): The objective of this proposal is to characterize the signaling pathways that mediate the growth-promoting effects of IGF-I and IGF-binding protein-5 (IGFBP-5), and the growth-inhibiting effects of TGF-beta1 and IGFBP-on human intestinal smooth muscle cells. The experimental approach utilizes normal human intestinal muscle cell during growth in culture, which recapitulates the rapid growth of muscle tissue in the developing or inflamed intestine. Previous studies have shown that the levels of IGF-I and IGFBP-5 produced by growing cells are high during the proliferative phase and decline with the approach of confluence, whereas the levels of TGF-beta1 an IGFBP-3 are highest after the cells attain confluence. The hypotheses that underlie the Specific Aims of the current proposal are that the growth factors and binding proteins activate stimulatory and inhibitory signaling pathways that regulate: (i) the expression of IGF-I receptors; (ii) the production of growth factors and binding proteins, and their ability to promote or inhibit growth; and (iii) the progress of the cell cycle from the G 1 to the S phase. The Specific Aims are to: (1) characterize the regulation of IGF-I receptor expression by IGF-I, TGF-beta1 IGFBP-5, and IGFBP-3 during culture; (2) characterize the signaling pathways that mediate the stimulatory effects of IGF-I and IGFBP-5, and inhibitory effects ofTGF-B1 and IGFBP-3 on cell growth and the production of growth factors and binding proteins; and (3) identify the signals that regulate cell cycle progression from the G1 to S phase. Each Specific Aim is supported by substantial preliminary data. IGF-I and IGFBP-5 are linked by reciprocal pathways that regulate their production, growth-promoting effects, and ability to inhibit IGF-I receptor expression. The pathways include activation of p42/44 MAP kinase and PI 3-kinase by IGF-I receptor tyrosine kinase, an activation of p38 MAP kinase by IGFBP-5 receptor serine kinase. TGF-beta1 and IGFBP-3 activate TGF-beta1 receptor serine kinase leading to Smad2 phosphorylation and inhibition of IGF-I receptor phosphorylation. IGF-I stimulates cyclin Dl expression, cdk4 activity, and pRb phosphorylation, and TGF-beta1 stimulates the cdk inhibitor, p15INK4B. The studies provide an analysis of the cellular mechanisms that determine initiation and cessation of muscle growth.