Role and regulation of MEF2C in retinal angiogenesis

描述(申请人提供)：视网膜新生血管(NV)在美国和发达国家是导致失明的主要原因。血管内皮生长因子(VEGF)在刺激视网膜新生血管中起重要作用。虽然对视网膜血管生成的上游信号机制了解很多，但对转录因子在这一过程中的调控和作用知之甚少。我们的实验室对阐明重要的转录因子非常感兴趣，这些转录因子介导了血管内皮生长因子对视网膜新生血管的影响。心肌细胞增强因子2C(MEF2C)是一种MADS-box(MCM1，AGamous，Deficiens，血清反应因子-box)转录因子，是血管发育所必需的。靶向缺失MEF2C会导致严重的血管异常和小鼠胚胎死亡。我们实验室的初步数据表明，MEF2C在血管内皮生长因子的功能和视网膜血管生成中起重要作用：(1)在蛋白激酶C(PKC)依赖的方式下，血管内皮细胞(HRECs)中的MEF2C的表达显著增加；(2)在VEGF诱导的趋化实验中，抑制MEF2C显著阻止视网膜内皮细胞的迁移。我们的总体假设是，MEF2C在基因表达和功能活性水平上都诱导了视网膜血管生成，并且MEF2C在介导视网膜血管生成中发挥了重要作用。为了验证我们的假设，我们将使用纯化的人视网膜内皮细胞和具有良好特性的视网膜NV(氧气诱导的视网膜病变模型)的小鼠模型。我们将依次检测MEF2C基因表达的调节、MEF2C活性的调节以及MEF2C在视网膜血管生成中的功能作用。因此，我们提出了以下三个特定目标：特定目标1.验证MEF2C基因在视网膜新生血管形成过程中受血管生成生长因子调控的假设。具体目的2.验证血管内皮生长因子通过促进MEF2C核转位、DNA结合和转录激活来调节MEF2C活性的假设。具体目的3.验证MEF2C在视网膜NV中起重要作用的假说。靶向转录因子作为治疗癌症和心力衰竭等疾病的方法正受到越来越多的关注。进一步了解MEF2C的调节和作用同样可能导致治疗视网膜新生血管和其他眼部血管生成疾病的新治疗策略。

DESCRIPTION (provided by applicant): Retinal neovascularization (NV) is a major cause of blindness in the United States and developed countries. Vascular endothelial growth factor (VEGF) plays a major role in stimulating retinal neovascularization. Although much is known about the upstream signaling mechanisms in retinal angiogenesis, relatively less is known about the regulation and role of transcription factors in this process. Our laboratory is very interested in elucidating important transcription factors that mediate VEGF's effect on retinal NV. Myocyte enhancer factor 2C (MEF2C) is a MADS-box (MCM1, Agamous, Deficiens, serum response factor-box) transcription factor which is required for vascular development. Targeted deletion of MEF2C results in severe vascular abnormalities and embryonic lethality in mice. Preliminary data in our lab suggests an important role for MEF2C in VEGF function and retinal angiogenesis: (1) VEGF strongly increases MEF2C expression in human retinal endothelial cells (HRECs) in a protein kinase C (PKC)-dependent manner; (2) VEGF activates MEF2C function in HRECs; and (3) inhibition of MEF2C significantly blocks retinal endothelial cell migration in a VEGF-induced chemotaxis assay. Our overall hypothesis is that MEF2C is induced in retinal angiogenesis both at the level of gene expression and functional activity, and that MEF2C plays an important role in mediating retinal angiogenesis. In order to test our hypothesis, we will use purified human retinal endothelial cells and a well-characterized mouse model of retinal NV (the oxygen-induced retinopathy model). We will sequentially examine the regulation of MEF2C gene expression, regulation of MEF2C's activity, and the functional effect of MEF2C in retinal angiogenesis. Accordingly, we propose the following three specific aims: Specific Aim 1. Test the hypothesis that MEF2C gene expression is regulated during retinal NV by angiogenic growth factors. Specific Aim 2. Test the hypothesis that VEGF regulates MEF2C activity by promoting MEF2C nuclear translocation, DNA binding, and transcriptional activation. Specific Aim 3. Test the hypothesis that MEF2C plays an important functional role in retinal NV. The targeting of transcription factors is receiving increasing attention as a therapeutic approach for disease processes including cancer and heart failure. Further understanding of the regulation and role of MEF2C could similarly lead to new therapeutic strategies for treating retinal NV and other ocular angiogenic disorders.