Growth and Function of Cultured Gastrointestinal Muscle

描述（由申请人提供）：这项工作的总体假设是α ν β 3整联蛋白及其配体、纤连蛋白和玻连蛋白调节正常组织中IGF-I刺激的生长，并且它们与IGF-I和IGFBP 5在炎症中的增加的产生在启动平滑肌增生中是至关重要的。人肠平滑肌的生长部分通过内源性生长肽的相互作用来调节。我们在上一个资助期间的研究已经确定了两种生长因子，IGF-I和IGFBP-5，它们共同作用于调节人类肠道平滑肌生长。内源性IGF-I通过IGF-I受体刺激增殖并抑制凋亡。IGFBP-5促进IGF-I对IGF-I受体的激活。IGFBP-5还通过激活其自身的IGFBP- 5受体来刺激肠平滑肌的生长。IGF-I和IGFBP-5之间刺激生长和彼此分泌的独特相互作用加强了它们对生长的单独作用，并可能导致肠道炎症引起的肌肉增生。初步结果表明，IGF-I受体激活，肌肉生长和IGFBP-5分泌刺激IGF-I调节的aV <$3整合素，并可以增强aV <$3整合素配体，纤连蛋白。我们发现，纤维连接蛋白和玻连蛋白在发炎的肠肌中上调。因此，本提案的目的是确定α V 3整合素及其配体、纤连蛋白和玻连蛋白调节IGF-I受体活性的机制，以及这些α V 3配体以及IGF-I和IGF结合蛋白-5（IGFBP-5）在炎症期间启动肌肉增生中表达增加的意义。 第一个具体目标是表征肠平滑肌细胞中aV 3整合素信号通路对IGF-I刺激的IGF-I受体磷酸化的调节。第二个目的是检查IGF-I刺激的肌细胞增殖的调节，IGFBP-5的上调;以及内源性α V 3整合素配体对细胞凋亡的抑制。第三个具体目标是确定上调的α ν 3整合素配体在炎症肠平滑肌中启动改变的IGF-I刺激的生长中的作用。每个具体目标都得到大量初步研究的支持。他们的完成应该推进我们对正常肌肉中平滑肌生长的调节和在炎症环境中启动平滑肌增生的关键机制的理解。

DESCRIPTION (provided by applicant): The overall hypotheses underlying this work are that aV¿3 integrin and its ligands, fibronectin and vitronectin, regulate IGF-I stimulated growth in normal tissue, and that their increased production together with IGF-I and IGFBP5 in inflammation are crucial in initiating smooth muscle hyperplasia. Growth of human intestinal smooth muscle is regulated in part through the interplay of endogenous growth peptides. Our studies during the previous funding period have identified two growth factors, IGF-I and IGFBP-5, which act in concert to regulate human intestinal smooth muscle growth. Endogenous IGF-I stimulates proliferation and inhibits apoptosis via the IGF-I receptor. IGFBP-5 facilitates activation of the IGF-I receptor by IGF-I. IGFBP-5 also stimulates growth of intestinal smooth muscle by activating its own IGFBP- 5 receptor. A unique interaction between IGF-I and IGFBP-5 to stimulate growth and each others' secretion reinforces their individual effects on growth and may contribute to the muscle hyperplasia resulting from intestinal inflammation. Preliminary results showed that IGF-I receptor activation, muscle growth and IGFBP-5 secretion stimulated by IGF-I were regulated by the aV¿3 integrin and could be augmented by the aV¿3 integrin ligand, fibronectin. We showed that fibronectin and vitronectin are upregulated in inflamed intestinal muscle. The objective of this proposal therefore is to determine the mechanisms by which the aV¿3 integrin and its ligands, fibronectin and vitronectin, regulate IGF-I receptor activity and the significance of increased expression of these aV¿3 ligands as well as IGF-I and IGF binding protein-5 (IGFBP-5) in initiating muscle hyperplasia during inflammation. The first specific aim is to characterize the regulation of IGF-I-stimulated IGF-I receptor phosphorylation by aV¿3 integrin signaling pathways in intestinal smooth muscle cells. The second aim is to examine the regulation of IGF-I-stimulated muscle cell proliferation, upregulation of IGFBP-5; and inhibition of apoptosis by endogenous aV¿3 integrin ligands. The third specific aim is to identify the role of upregulated aV¿3 integrin ligands in initiating altered IGF-I-stimulated growth in inflamed intestinal smooth muscle. Each specific aim is supported by substantial preliminary studies. Their completion should advance our understanding of the regulation of smooth muscle growth in normal muscle and mechanisms crucial to initiating smooth muscle hyperplasia in the setting of inflammation.