Role of MMPs in TGFbeta-induced Cataract Formation

上皮-间充质转化(EMT)在肾间质纤维化中起重要作用。 多个器官和组织，包括人工晶状体，在那里它对前囊下的两个部分起作用 白内障(ASC)和后囊混浊(PCO)，也称为继发性白内障。 促进晶状体上皮细胞(LECs)的增殖，以及LECs向肌成纤维细胞的EMT，涉及 细胞-细胞黏附分子E-钙粘附素的缺失和平滑肌肌动蛋白的诱导 (？)SMA的表达是ASC和PCO的早期事件。转化生长因子β(TGF)是 一种多效性的形态原，已被证明能诱导晶状体上皮细胞的EMT，并随后形成 ASC以及PCO。使用先前建立的大鼠晶状体培养模型，在该模型中，外源性转化生长因子？ 诱导ASC我们已经证明，用基质金属蛋白酶(MMPs)的抑制剂治疗， 具体地说，基质金属蛋白酶-2和基质金属蛋白酶-9抑制转化生长因子诱导的白内障改变，包括EMT。 上一次赠款期间的研究进一步表明，这两个MMP很可能是协同工作的 和/或在这些白内障的发展中多余的。例如，使用ASC的模型 我们已经证明，在向眼睛输送AdTGF的过程中，MMP-9 KO小鼠会患上白内障。 尽管与野生型小鼠相比，它们要延迟一些。因此，可能需要同时抑制两种MMP 预防EMT和继发性白内障的发生。这些MMP的潜在机制 中度EMT和白内障的形成是在上一次筹资期间发现的，涉及 E-钙粘附素的干扰。初步数据表明，E-钙粘素的破坏和脱落会导致 在与EMT相关的下游信号事件中，包括连环蛋白的核转位和 肌钙蛋白相关转录因子(MRTF-A)。然而，对这些信令的要求 ASC和PCO中的中间体以及MMP是如何参与的尚不清楚。在目前的提案中，我们 用多种体外和体内ASC模型研究这些转化生长因子介导的信号通路 和PCO。此外，我们还概述了将直接确定唯一和/或 基质金属蛋白酶-2和基质金属蛋白酶-9在ASC形成中的协同作用最终，我们的目标是定义转化生长因子？- ASC和PCO中控制EMT和纤维化的介导性通路，以设计治疗 减轻这些疾病。

Epithelial-mesenchymal transition (EMT) has been shown to play an important role in the fibroses of multiple organs and tissues, including the ocular lens, where it contributes to both anterior subcapsular cataracts (ASC) and posterior capsular opacification (PCO), also known as secondary cataract. Increased proliferation of lens epithelial cells (LECs), and EMT of LECs into myofibroblasts, involving a loss of the cell-cell adhesion molecule E-cadherin and an induction in ¿-smooth muscle actin (¿SMA) expression are early events in both ASC and PCO. Transforming growth factor beta (TGF¿) is a pleotropic morphogen that has been shown to induce the EMT of LECs and subsequent formation of ASC, as well as, PCO. Using a previously developed rat lens culture model in which exogenous TGF¿ induces ASC we have shown that treatment with inhibitors to the matrix metalloproteinases (MMP), specifically MMP-2 and MMP-9, suppresses TGF¿-induced cataractous changes, including EMT. Studies from the previous grant period further show that these two MMPs likely work cooperatively and/or redundantly in the development of these cataracts. For example, using a model of ASC involving the delivery of AdTGF¿ to the eye we have shown that MMP-9 KO mice develop cataracts, albeit they are delayed compared to wild-type mice. Thus, inhibiting both MMPs may be required to prevent EMT and subsequent cataractogenesis. The potential mechanism by which these MMPs mediate EMT and cataract formation was identified during the previous funding period and involves disruption of E-cadherin. Preliminary data suggests that disruption and shedding of E-cadherin results in downstream signaling events linked to EMT including nuclear translocation of ¿-catenin and the myocardin-related transcription factor (MRTF-A). However, the requirement for these signaling intermediates in ASC and PCO and how MMPs are involved is not known. In the current proposal we investigate these TGF¿-mediated signaling pathways using multiple ex vivo and in vivo models of ASC and PCO. In addition, we outline experiments that will directly determine the unique and/or cooperative roles of MMP-2 and MMP-9 in ASC formation. Ultimately, our goal is to define the TGF¿- mediated pathways controlling EMT and fibrosis in ASC and PCO in order to design therapeutics for mitigating these diseases.