Integrin Shedding in the Heart: In vivo and in vitro

描述（由申请人提供）：在生长和发育过程中， 心脏，细胞外基质（ECM）的成分保持精确， 3-三维排列，胶原附着在肌细胞的Z带附近。 ECM的这种排列与心脏功能密切相关， 这些连接的改变可导致异常生长和改变 模式化ECM的主要细胞表面受体是 整合素家族。然而，这些整合素连接的机制 ECM随生长的变化是未知的。针对病理生理学 信号心肌细胞经历大小（肥大）或形状的增加 （扩张），ECM：肌细胞连接也必须适应这些变化。 心脏成纤维细胞也显示出响应于生长的适应性变化， 通过改变胶原蛋白沉积、迁移和 增殖最近的数据表明，整合素与 ECM在生长和发育过程中脱落其胞外域;然而， 这一过程的机制和功能尚不清楚。拟议的研究将 解决整合素脱落代表改变 受体-ECM相互作用，允许细胞生长和表型的变化 并且脱落整合素胞外域对心脏和外周血具有调节功能， 成纤维细胞和肌细胞。解决这一假设的具体目标是 目的是：1）确定哪些特定的整联蛋白正在脱落; 2）确定 负责脱落的机制;以及3）确定 为了达到这些特定目的， 以及体内和体外心脏模型中的分子技术 将使用肥大和扩张。初步数据显示， 负责脱落的酶可能是基质的成员 金属蛋白酶（MMP）家族或A去整合素和金属蛋白酶（ADAM） 家人特定的抑制剂将用于确定哪些特定的 MMP或亚当斯参与脱落过程。各种生化 以及细胞行为测定，包括受体数量、胶原蛋白 合成、细胞迁移和胶原凝胶收缩将用于 确定脱落片段对心肌细胞的潜在功能， 成纤维细胞拟议的研究将提供以下方面的全新信息： 整合素、ECM和心脏生长调节的动态相互作用， 发展

DESCRIPTION (provided by applicant): During the growth and development of the heart, the components of the extracellular matrix (ECM) maintain a precise, 3-dimensional arrangement with collagen attaching near the Z band of myocytes. This arrangement of the ECM is intimately associated with cardiac function and alteration of these connections can result in abnormal growth and altered patterning. The principal cell surface receptors for the ECM are the members of the integrin family. However, the mechanism of how these integrin connections with the ECM change with growth is unknown. In response to pathophysiological signals cardiac myocytes undergo an increase in size (hypertrophy) or shape (dilation), the ECM:myocyte connection also must accommodate these changes. Cardiac fibroblasts also show adaptive changes in response to growth and developmental signals by altered collagen deposition, migration, and proliferation. Recent data has demonstrated that the integrin connections with the ECM shed their ectodomains during growth and development; however, the mechanism and function of this process is unknown. The proposed research will address the hypothesis that integrin shedding represents a method of altering receptor-ECM interaction which allows for changes in cell growth and phenotype and that the shed integrin ectodomain has a regulatory function on both cardiac fibroblasts and myocytes. The specific aims that will addresses this hypothesis are to: 1) determine which specific integrins are being shed; 2) determine the mechanism responsible for shedding; and 3) determine the potential function of the shed integrin ectodomain, To address these specific aims, a variety of cell and molecular techniques in both in vivo and in vitro models of cardiac hypertrophy and dilation will be used. Preliminary data indicates that the enzymes responsible for the shedding are likely to be members of the Matrix Metalloprotease (MMP) family or A Disintegrin And Metalloprotease (ADAM) family. Specific inhibitors will be used to determine which of the specific MMPs or ADAMS are involved in the shedding process. A variety of biochemical and cell behavior assays including regulation of receptor number, collagen synthesis, cell migration and collagen gel contraction will be used to determine potential functions of the shed fragment on cardiac myocytes and fibroblasts. The proposed studies will provide fundamentally new information on the dynamic interaction of integrins, ECM and regulation of cardiac growth and development.