OSTEOPONTIN IN HEART & ITS ROLE IN MYOCARDIAL REMODELING

细胞外基质(ECM)在重塑中起重要作用 心肌损伤后的心脏过程。我的长期目标是 研究其生化生理功能及其调节。 骨桥蛋白(OPN)，一种细胞外基质蛋白。我们的初步数据显示，OPN 在心肌梗死后的小鼠心脏中显著诱导 (Mi)。我们还发现诱导型一氧化氮合酶(INOS) 基因在心肌梗塞后的小鼠心脏中表达，因此可能是 通过贡献活性氧物种而造成氧化应激的来源 (ROS)。我们先前已经证明，OPN抑制诱导 INOS基因在体外培养的心肌细胞中的表达 提供了OPN可以降低细胞氧化剂水平的证据。这些 综合观察，我们得出了这样的假设，即 OPN可减轻一氧化氮(NO)和ROS介导的细胞损伤 心肌重构过程中的一种保护功能 在MI之后。 为了验证这一假设，我们将使用最近开发的小鼠模型 冠脉结扎所致慢性心肌衰竭与OPN基因敲除 老鼠。我们将研究形态、生理和分子参数 心肌重塑和心力衰竭的关系，并在野生型中进行比较 和OPN基因敲除小鼠心肌梗死。在第一组实验中， 我们将检查粗大的左心室(LV)腔形态， 结构(细胞凋亡、纤维化和肥大)和左心功能。至 探讨OPN改变心肌重塑的机制 心肌梗死后，我们将测量NO的产生(通过测量iNOS 基因表达和诱导型一氧化氮合酶活性)和超氧化物歧化酶(光量子素法) 野生型和OPN基因敲除小鼠的心肌梗死。使用体外细胞 培养，我们将研究MAPK通路在OPN介导的过程中的作用。 抑制细胞因子诱导的iNOS表达。在第三盘 使用原位杂交和免疫组织化学 分析，我们将确定参与表达的细胞类型 心肌梗死后心肌中的OPN。利用细胞黏附，放射- 碘标记和免疫沉淀分析，我们将确定 两种主要细胞(微血管内皮细胞)上的OPN受体 细胞和肌细胞)。细胞类型的鉴定(S) 参与OPN的表达将指导未来的体外研究 确定OPN在心肌中表达的调控机制。 这些研究将促进我们对这一过程的理解 心肌梗死后发生的重塑可能导致新的治疗方法 治疗心力衰竭的方法。

Extracellular matrix (ECM) contributes significantly to remodeling processes of heart following myocardial damage. My long term goal is to study the biochemical and physiological functions and regulation of osteopontin (OPN), an ECM protein. Our preliminary data show that OPN is markedly induced in the mouse heart following myocardial infraction (MI). We have also found that the inducible nitric oxide synthase (iNOS) gene is expressed in the mouse heart following MI, and may therefore be a source of oxidative stress by contributing reactive oxygen species (ROS). We previously demonstrated that OPN inhibits the induction of iNOS gene expression in cardiac myocytes in vitro, and others have provided evidence that OPN can reduce cellular oxidant levels. These observations, taken together, have led us to the hypothesis that, by attenuating nitric oxide (NO)-and ROS-mediated cell damage, OPN serves a protective function during the myocardial remodeling that occurs following MI. To test this hypothesis we will use a recently developed mouse model of chronic myocardial failure caused by coronary ligation, and OPN-knockout mice. We will study morphologic, physiologic and molecular parameters of myocardial remodeling and heart failure and compare them in wild type and OPN-knockout mice subjected to MI. In the first set of experiments, we will examine gross left ventricular (LV) chamber morphology, structure (apoptosis, fibrosis and hypertrophy) and LV function. To address the mechanism by which OPN modifies myocardial remodeling following MI, we will measure the production of NO (by measuring iNOS gene expression and iNOS activity) and superoxide (by lucigenin assay) in wild-type and OPN-knockout mice subjected to MI. Using in vitro cell culture, we will study the involvement of MAPK-pathway in OPN-mediated suppression of iNOS expression induced by cytokines. In the third set of experiments, using in situ hybridization and immunohistochemical analysis, we will identify the cell types involved in the expression of OPN in the myocardium following MI. Using cell adhesion, radio- iodination and immunoprecipitation assays, we will identify the receptors for OPN on two major cell types (microvascular endothelial cells and myocytes) of the heart. The identification of cell type(s) involved in the expression of OPN will guide future in vitro studies to determine the mechanism that regulates OPN expression in the myocardium. These studies will advance our understanding of the process of remodeling which occurs after MI and could lead to new therapeutic approaches to heart failure.