Regulation of Cardiac Collagen Content by SLIT3

项目总结 心脏纤维化是一种常见的不良心肌重塑事件，可加重慢性心力衰竭 室压超负荷和其他心脏病变，如射血分数保留的心力衰竭。 由于对心肌纤维化发病机制的认识不完全，目前尚无特效的抗纤维化治疗方法。 存在，受影响的患者通常通过心脏移植进行治疗，这一疗法有许多局限性。 在这个临床问题的推动下，我们的研究最近发现了对心脏调节的新见解 胶原蛋白含量和纤维化，在这一应用中，我们建议扩展这项工作，以进一步获得 对细胞和分子机制的理解。在我们最近的研究中，我们发现全球范围内的缺陷 SLIT3，一种与ROBO受体结合的分泌型糖蛋白，导致心脏明显减少 胶原蛋白含量，改善成年小鼠的舒张期功能，减少心脏纤维化，提高存活率 横动脉缩窄(TAC)引起左心室(LV)压力超负荷后。我们还发现， SLIT3在体外刺激心脏成纤维细胞功能、细胞内信号转导和胶原蛋白的产生。总而言之， 这些结果支持SLIT3与正常心脏组织中胶原沉积之间的发育联系 动态平衡和病理性应激。然而，由于这些研究依赖于SLIT3全局基因敲除小鼠，其中 SLIT3基因敲除可能会影响发育程序，SLIT3的出生后功能越具体- 以及细胞和分子信号的细节-在成年状态下仍未确定。新的初稿 使用SLIT3配对的小鼠和可诱导的Cre启动子的数据，我们发现SLIT3，由两个心脏 周细胞或成纤维细胞，在体外和体内调节出生后状态下的胶原表达，很可能是通过 通过Robo1发送信号。基于这些结果，我们的主要假设是心脏周细胞和 成纤维细胞介导的SLIT3通过Robo1调节成纤维细胞的激活和功能 动态平衡和压力过载。因此，我们提出以下目标：(1)确定SLIT3的作用 在体内调节成人心脏成纤维细胞的功能。(2)确定SLIT3/Robo1如何调控的细节 体内和体外成人心脏成纤维细胞的激活和功能。(3)确定心肌周细胞的作用 成纤维细胞介导的SLIT3对心脏成纤维细胞Robo1依赖反应的影响 体内过载。这项研究将揭示心脏成纤维细胞调控的新细胞和分子概念 并将进一步促进我们对心肌纤维化发病机制的认识。这项研究的结果 可提供靶向SLIT3-Robo1以减轻压力超负荷诱导的心肌纤维化的理论基础， 从而使心力衰竭和其他形式的心脏病患者受益。

PROJECT SUMMARY Cardiac fibrosis is a common adverse myocardial remodeling event that worsens heart failure caused by chronic ventricular pressure overload and other cardiac pathologies such as heart failure with preserved ejection fraction. Due to our incomplete understanding of the pathogenesis of cardiac fibrosis, no specific antifibrotic therapy exists, and affected patients are usually treated by heart transplantation, a therapy that has many limitations. Motivated by this clinical problem, our research has recently uncovered new insights into the regulation of cardiac collagen content and fibrosis, and, in this application, we propose to extend this work to gain further understanding into cellular and molecular mechanisms. In our recent work, we discovered that global deficiency of SLIT3, a secreted glycoprotein which binds to the ROBO receptors, leads to a marked decrease in cardiac collagen content, improved diastolic function in adult mice, and decreased cardiac fibrosis and improved survival after left ventricle (LV) pressure overload induced by transverse aortic constriction (TAC). We also found that SLIT3 stimulates cardiac fibroblast function, intracellular signaling, and collagen production in vitro. Collectively, these results support a developmental link between SLIT3 and collagen deposition during both normal cardiac homeostasis and pathologic stress. However, as these studies relied on SLIT3 global knockout mice where SLIT3 knockout potentially affected developmental programs, the more specific, postnatal functions of SLIT3 - as well as the details of the cellular and molecular signaling - remain undefined in the adult state. New preliminary data using SLIT3 floxed mice and inducible Cre promoters, we find that SLIT3, generated by either cardiac pericytes or fibroblasts, regulates collagen expression in vitro and in vivo in the postnatal state, most likely, by signaling through ROBO1. Based on these results, our overarching hypothesis is that cardiac pericyte and fibroblast-mediated SLIT3 regulate fibroblast activation and function via ROBO1 during conditions of homeostasis and pressure overload. As such, we propose the following aims: (1) Characterize the role of SLIT3 in regulating adult cardiac fibroblast function in vivo. (2) Determine the details of how SLIT3/ROBO1 regulates adult cardiac fibroblast activation and function in vivo and in vitro. (3) Characterize the role of cardiac pericyte and fibroblast-mediated SLIT3 on the ROBO1-dependent response of cardiac fibroblasts during LV pressure overload in vivo. This research will reveal new cellular and molecular concepts of cardiac fibroblast regulation and will further advance our understanding of the pathogenesis of cardiac fibrosis. The results of this research may provide the rationale for targeting SLIT3-ROBO1 to mitigate pressure overload-induced cardiac fibrosis, thereby benefiting patients with heart failure and other forms of cardiac disease.