Role and regulation of MEF2C in retinal angiogenesis

描述（由申请人提供）：视网膜新生血管（NV）是美国和发达国家失明的主要原因。血管内皮生长因子（VEGF）在刺激视网膜新生血管中起着重要作用。虽然对视网膜血管生成的上游信号机制了解甚多，但对转录因子在这一过程中的调节和作用知之甚少。我们的实验室对阐明介导VEGF对视网膜NV影响的重要转录因子非常感兴趣。肌细胞增强因子2C （Myocyte enhancer factor 2C, MEF2C）是血管发育所需的MADS-box （MCM1, Agamous，缺陷，血清反应因子盒）转录因子。MEF2C的靶向缺失会导致小鼠严重的血管异常和胚胎死亡。我们实验室的初步数据表明MEF2C在VEGF功能和视网膜血管生成中起重要作用：(1)VEGF以蛋白激酶C （PKC）依赖的方式强烈增加MEF2C在人视网膜内皮细胞（HRECs）中的表达；(2) VEGF激活HRECs中MEF2C功能；(3)在vegf诱导的趋化实验中，MEF2C的抑制显著阻止了视网膜内皮细胞的迁移。我们的总体假设是MEF2C在基因表达水平和功能活性水平上诱导视网膜血管生成，MEF2C在介导视网膜血管生成中发挥重要作用。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征的视网膜NV小鼠模型（氧诱导视网膜病变模型）。我们将依次研究MEF2C基因表达的调控、MEF2C活性的调控以及MEF2C在视网膜血管生成中的功能作用。为此，我们提出以下三个具体目标：验证MEF2C基因表达在视网膜NV中受血管生成生长因子调控的假设。具体目标2。验证VEGF通过促进MEF2C核易位、DNA结合和转录激活来调节MEF2C活性的假设。具体目标3。验证MEF2C在视网膜NV中起重要功能作用的假设。靶向转录因子作为一种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的调控和作用，同样可以为治疗视网膜NV和其他眼部血管生成疾病提供新的治疗策略。

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.