Type VI collegen and integrins in cardiac remodeling

描述（由申请人提供）：高血压、心脏肥厚和心力衰竭是引起心脏成纤维细胞（心脏中主要结缔组织细胞）表型和生理显著改变的病理生理过程。心脏成纤维细胞对这些应激源的反应是高分泌、高增殖，并分化为肌成纤维细胞。肾素-血管紧张素系统引起的细胞信号的改变与这种重塑过程有关。然而，我们计划研究这一过程中另一种潜在介质的作用：改变细胞-细胞外基质相互作用。我们将研究整合素受体和基质，特别是VI型胶原，在心脏成纤维细胞功能中的作用。VI型胶原蛋白会引起细胞的生理和表型变化，缺乏这种胶原蛋白会导致像Bethlem这样的肌病。我们将讨论两个具体目标。在特异性目标1中，我们将使用免疫细胞化学技术检查异丙醇诱导的心脏纤维化中体内整合素谱、基质沉积和肌成纤维细胞分化。为了研究VI型胶原蛋白在心脏重塑中的作用，我们将利用转基因小鼠贝氏肌病模型。所有实验将使用野生型、杂合型和突变型col6a1小鼠进行，以确定整合素和VI型胶原在心脏重塑中的作用。在特异性目标2中，我们将评估特异性整合素亚单位和VI型胶原在体外的作用。将从col6a1 +/+、+/-和-/-小鼠心脏中分离成纤维细胞，并进行各种检测。利用免疫细胞化学技术分析基质沉积、粘附、迁移、增殖和肌成纤维细胞的体外分化。为了确定特异性整合素的作用，需要使用功能阻断抗体。这将使我们能够表征整合素底物的相互作用，细胞沉积型胶原蛋白的作用，以及异丙醇诱导的细胞损伤。这些研究将使我们能够确定整合素和VI型胶原在体外心脏成纤维细胞生理和体内心脏重塑中的作用。

DESCRIPTION (provided by applicant): Hypertension, cardiac hypertrophy and heart failure are pathophysiological processes that cause significant alterations in the phenotype and physiology of cardiac fibroblasts, the major connective tissue cell in the heart. Cardiac fibroblasts respond to these stressors by becoming hypersecretory, hyperproliferative, and differentiating into myofibroblasts. Altered cell signaling due to the renin-angiotensin system has been implicated in this remodeling process. However, we plan to examine the role of another potential mediator this process: altered cell-extracellular matrix interactions. We will examine the role of integrin receptors and matrix, specifically type VI collagen, in cardiac fibroblast function. Type VI collagen causes physiological and phenotypic changes in cells, and lack of this collagen causes myopathies such as Bethlem's. We will address two specific aims. In Specific Aim 1, we will examine integrin profiles, matrix deposition, and myofibroblast differentiation in vivo in isoproteranol-induced cardiac fibrosis using immunocytochemical techniques. To address the role of type VI collagen in cardiac remodeling, a transgenic mouse model of Bethlem's myopathy will be utilized. All experiments will be performed using wild type, heterozygous and mutant col6a1 mice, to determine the role of integrins and type VI collagen in cardiac remodeling. In Specific Aim 2, we will evaluate the role of specific integrin subunits and type VI collagen in vitro. Fibroblasts will be isolated from col6a1 +/+, +/-, and -/- mouse hearts, and a variety of assays performed. Matrix deposition, adhesion, migration, proliferation, and myofibroblast differentiation in vitro will be analyzed using immunocytochemical techniques. To determine the role of specific integrins, function blocking antibodies be utilized. This will allow us to characterize integrin-substrate interactions, the role of cell-deposited type collagen, and isoproteranol-induced cellular injury. These studies will allow us to determine the role of integrins and type VI collagen in cardiac fibroblast physiology in vitro, and cardiac remodeling in vivo.