Talin1 Function in Cardiac Myofibroblasts

项目摘要 心力衰竭(HF)影响着越来越多的人口，目前影响着500多万成年人。 仅美国一国。由于慢性左心室压力超负荷，组织力学是永久性的 随着间质纤维化和心肌肥大的发生而改变。尽管心力衰竭很普遍，但在那里 除了左心室辅助之外，没有逆转甚至减少心脏纤维化的治疗策略 设备和心脏移植，由于对常驻心肌细胞的机械生物学反应知之甚少。 压力超负荷致心衰期间，心脏成纤维细胞向激活的肌成纤维细胞转化 (MyoFBs)，转向更收缩和高分泌的表型。MyoFBs表达Talin1(Tln1)，a 一种焦点黏附蛋白，激活整合素并经历力诱导的机械折叠，允许 MyoFB附着在细胞外基质(ECM)上并将力传递给ECM。初步数据 证明MyoFB Tln1可能与心力衰竭发生的不良重塑和缺失有关 在心衰过程中，在MyoFBs中应用这种蛋白可能会改善心功能，减少纤维化。因此，中央 目前提出的假设是MyoFB特异性缺失Tln1会减少间质纤维化，减少 在心力衰竭的情况下，左心室肥厚，并保护心功能。我们首先要确定的是 选择性地从MyoFBs中删除Tln1以减少周围心肌的不良重构 对压力过载的响应(Aim1)。在建立Tln1作为MyoFB机械生物学和 纤维化，我们将调查Tln1介导的细胞外基质沉积MyoFBs有助于改变的假设 心衰时心肌细胞(CM)肥大(AIM2)。为了研究这些目的，一种新的MyoFB特异性Tln1基因敲除 鼠标已生成。横断性主动脉缩窄--压力超负荷的实验模型 将进行诱导心衰，并将使用超声心动图测量血流动力学功能。 在整个研究过程中，老鼠的心脏。间质纤维化和左心室僵硬的特征是 天狼星红染色和原子力显微镜。CM肥大的特征将使用 小麦胚芽凝集素染色。体外模型将被用来分离ECM刚性和ECM的影响。 原纤维厚度。CM和Tln1-/-MyoFB对这些不同机械刺激的反应将使用 牵引力显微镜和微吸管吸引术。总之，这项提案的结果将确立 MyoFB Tln1作为MyoFB介导的心肌纤维化和心肌肥厚的调节因子将突出一个新的 心衰治疗和管理的治疗目标。

Project Summary Heart failure (HF) affects an expanding proportion of the population, and currently affects over 5 million adults in the United States alone. Due to chronic pressure overload of the left ventricle, tissue mechanics are permanently changed as interstitial fibrosis and hypertrophy of the myocardium occurs. Despite the prevalence of HF, there are no therapeutic strategies to reverse – or even reduce – cardiac fibrosis, aside from left ventricular assist devices and heart transplant, due to the poorly understood mechanobiological response of resident cardiac cells. During pressure overload induced HF, resident cardiac fibroblasts transition to activated myofibroblasts (MyoFBs), switching to the more contractile and hyper-secretory phenotype. MyoFBs express Talin1 (Tln1), a focal adhesion protein which activates integrins and undergoes force-induced mechanical unfolding, allowing for MyoFB attachment and transmission of force to and from the extracellular matrix (ECM). Preliminary data demonstrate that MyoFB Tln1 could be responsible for the adverse remodeling that occurs in HF, and deletion of this protein in MyoFBs during HF may improve cardiac function and decrease fibrosis. Thus, the central hypothesis of the current proposal is that MyoFB-specific deletion of Tln1 will reduce interstitial fibrosis, decrease left ventricular hypertrophy, and preserve cardiac function in the context of HF. We will first determine the ability of selective deletion of Tln1 from MyoFBs to reduce adverse remodeling of the surrounding myocardium in response to pressure overload (Aim1). Upon establishing Tln1 as a regulator of MyoFB mechanobiology and fibrosis, we will investigate the hypothesis that Tln1-mediated ECM deposition by MyoFBs contributes to altered cardiomyocyte (CM) hypertrophy during HF (Aim2). To study these aims, a novel MyoFB-specific Tln1 knockout mouse has been generated. Transverse aortic constriction (TAC) - an experimental model of pressure overload induced HF - will be performed, and echocardiography will be used to measure hemodynamic function of the mouse heart throughout the studies. Interstitial fibrosis and stiffness of the left ventricle will be characterized by picrosirius red staining and atomic force microscopy, respectively. CM hypertrophy will be characterized using wheat germ agglutinin staining. In vitro models will be employed to isolate the effects of ECM stiffness and ECM fibril thickness. CM and Tln1-/- MyoFB responses to these different mechanical stimuli will be investigated using traction force microscopy and micropipette aspiration. In summary, the results from this proposal will establish MyoFB Tln1 as a regulator of MyoFB-mediated cardiac fibrosis and CM hypertrophy and will highlight a novel therapeutic target for the treatment and management of HF.