Role of MRTF signaling in proliferative vitreoretinopathy

项目总结/摘要 增生性玻璃体视网膜病变（PVR）是影响视网膜的纤维化并发症。在PVR中，视力丧失 视网膜上形成的疤痕组织收缩， 面PVR在约50%的眼后段外伤病例中发现， 孔源性视网膜脱离手术修复目前还没有可靠的PVR治疗方法， 因此，预防是重要的。这个项目的总体目标是解开分子机制 参与PVR开发以确定潜在干预目标。纤维化的触发因素，如 PVR是持续存在的肌成纤维细胞，一种细胞类型专门的ECM沉积和创伤 收缩。最近的研究表明，僵硬的ECM激活细胞内信号传导，对分化至关重要 肌成纤维细胞。反过来，肌成纤维细胞通过异常ECM反馈进一步增强ECM刚度， 沉积和交联。肌成纤维细胞和ECM刚性之间的这种正反馈回路维持了 肌成纤维细胞的存在及其抑制成功地预防了动物模型中的肺和肝纤维化。 然而，潜在的详细机制和涉及的分子是组织和细胞类型 依赖性，这种正反馈回路的作用还有待于在PVR中进行研究。过去的研究表明， PVR患者样本中存在参与ECM硬化的分子。我们的初步数据显示 已知受ECM刚度影响的两种关键分子，瞬时受体电位香草酸4（TRPV 4） 通道和肌心蛋白相关转录因子（MRTF），是肌成纤维细胞所必需的 视网膜色素上皮（RPE）和Müller神经胶质细胞的转分化，这两种常驻细胞类型给予 在PVR中增加成肌纤维细胞。此外，数据还显示另一种受刚度调节的分子， 改变MRTF靶向表达，TAZ与MRTF相互作用。我们建议进行研究， ECM硬度激活的机制导致肌成纤维细胞分化和PVR。在目标1中， 将检测ECM硬化分子对成肌纤维细胞分化和PVR的影响。详细的分子 通过TRPV 4和TAZ调节MRTF的机制，这是肌成纤维细胞分化的关键， 分别在Aim 2和3中测定。该项目有可能揭示关键的分子治疗 用于预防PVR和可能的其他纤维化疾病的靶点。

Project Summary/Abstract Proliferative vitreoretinopathy (PVR) is a fibrotic complication affecting the retina. In PVR, loss of visual acuity, and in severe cases blindness, is caused by contraction of scar tissue that form on the retinal surface. PVR is found in ~50% of posterior segment ocular trauma cases and about 5% of cases after surgical repair of rhegmatogenous retinal detachment. Reliable treatment for PVR is currently unavailable, and therefore, prevention is important. The overall goal of this project is to unravel molecular mechanisms involved in PVR development to identify targets for potential intervention. The trigger for fibrosis such as PVR is sustained presence of myofibroblasts, a cell type specialized ECM deposition and wound contraction. Recent studies show that stiff ECM activates intracellular signaling essential for differentiation of myofibroblasts. Myofibroblasts, in turn, feeds back to further enhances ECM stiffness via aberrant ECM deposition and crosslinking. This positive feedback loop between myofibroblasts and ECM rigidity sustains myofibroblast presence, and its inhibition successfully prevented lung and liver fibrosis in animal models. However, the underlying detailed mechanisms and molecules involved are both tissue and cell type dependent, and the role of this positive feedback loop is yet to be examine in PVR. Past studies show the presence of molecules involved in ECM stiffening in samples from PVR patients. Our preliminary data show two key molecules known to be affected by ECM stiffness, transient receptor potential vanilloid 4 (TRPV4) channel and myocardin-related transcription factor (MRTF), are required for myofibroblast transdifferentiation of retinal pigment epithelial (RPE) and Müller glia cells, two resident cell types that give rise to myofibroblasts in PVR. Further, data also show another molecule regulated by stiffness and known to alter MRTF target expression, TAZ, interacts with MRTF. We propose studies to determine molecular mechanisms activated by ECM stiffness leading to myofibroblast differentiation and PVR. In Aim1, the effect of ECM stiffening molecules on myofibroblast differentiation and PVR will be examine. Detailed molecular mechanism of regulating MRTF, which is key to myofibroblast differentiation, by TRPV4 and TAZ will be determined in Aim2 and 3, respectively. The project has the potential to uncover key molecular therapeutic targets for the prevention of PVR, and possibly other fibrotic diseases.