GLOMERULAR LAMININS--STRUCTURE AND FUNCTION

细胞-基质相互作用对细胞的生长至关重要。 粘附、增殖、分化和基质调节 合成.这些相互作用的特异性取决于 细胞外基质（ECM）蛋白的子集表达在一个 特定的区室和ECM蛋白受体的子集 由单个细胞表达。IV型胶原蛋白家族成员， 肾小球内存在层粘连蛋白（LM）， 独特，在其他肾脏和非肾脏疾病中分布有限 ECM。在肾小球硬化相关的肾脏疾病中， 硬化病变含有ECM蛋白， 新的表达。糖尿病的初步研究 肾病和系膜细胞（MC）的培养，我们已经表明， 系膜含有LM和胰岛素的独特同种型， 血管紧张素II调节它们的合成和积累。 基于 根据这些数据，我们假设正常MC分泌两类LM 异源三聚体，一类含有B2和巢蛋白， ECM组件。第二类包含独特的MC LM， 巢蛋白，集中在细胞表面，具有独特的 在肾小球内起作用。胰岛素和血管紧张素II 调节单个LM链的合成速率。在疾病 这些激素的水平升高， 在一段时间内，它们的影响导致LM的逐渐增加， 同种型通常以低丰度存在。这些变化导致 系膜结构和功能的改变， ECM合成的反馈调节，并最终有助于 肾功能丧失。 这些假设将通过以下具体目标进行审查： 1.两个新的LM链独特的MC将被克隆，测序， 测定MC LM的异源三聚体组成。 2.胰岛素和血管紧张素II介导的合成酶变化的机制 将确定单个LM链。B1单体的反馈调节 并且将定义其通过胰岛素和血管紧张素II的控制。 3.独特的MC LM的功能将通过其诱导 表型变化和基因激活。与肾小球的关系 将检查神经支配、瓦神经营养因子和伤口愈合/瘢痕形成 4.胰岛素和血管紧张素II介导的LM改变的相关性 同种型表达与糖尿病肾小球硬化的发展， 将使用这些疾病的体内模型来检查衰老。 这些研究将有助于提供有关结构和功能的基本信息， 独特的肾小球LM，并建立胰岛素和血管紧张素II的作用 肾小球疾病中LM合成和积累的调节。

Cell-matrix interactions are critically important to cellular adhesion, proliferation, differentiation and regulation of matrix synthesis. Specificity of these interactions is determined by the subset of extracellular matrix (ECM) proteins expressed in a particular compartment and the subset of ECM protein receptors expressed by individual cells. Family members of collagen IV and laminin (LM) that are present within glomeruli are relatively unique and have limited distribution in other renal and non-renal ECMs. In renal diseases associated with glomerulosclerosis, the sclerotic lesions contain ECM proteins normally present as well as newly expressed ones. In preliminary studies of diabetic nephropathy and mesangial cells (MC) in culture, we have shown-that the mesangium contains unique isoforms of LM and that insulin and angiotensin II regulate their synthesis and accumulation. Based on these data, we hypothesize that normal MC secrete two classes of LM heterotrimers, a class that contains B2 and entactin and influences ECM assembly. A second class contains unique MC LMs that lack entactin, are concentrated on the cell surface and have unique functions within the glomerulus. Insulin and angiotensin II regulate the rate of synthesis of individual LM chains. In disease states where levels of these hormones are elevated for significant periods of time, their effects lead to progressive increases in LM isoforms normally present in low abundance. These changes lead to alterations in the structure and function of the mesangium, alter feedback regulation of ECM synthesis and ultimately contribute to loss of renal function. These hypotheses will be examined by the following specific aims: 1. Two new LM chains unique to the MC will be cloned, sequenced, and the heterotrimeric composition of MC LMs determined. 2. The mechanisms of insulin and angiotensin II-mediated changes in synthes of individual LM chains will be determined. Feedback regulation by B1 monom and its control by insulin and angiotensin II will be defined. 3. The function of unique MC LMs will be assessed by their ability to induc phenotypic changes and gene activation. The relationship to glomerular innervation, tile neurotrophins, and wound healing/scarring will be examine 4. The relevance of insulin and angiotensin II-mediated alterations in LM isoform expression to the development of glomerulosclerosis in diabetes and aging will be examined using in vivo models of these diseases. These studies will contribute basic information on structure and function o unique glomerular LMs and establish the role of insulin and angiotensin II regulation of LM synthesis and accumulation in glomerular disease.