Role and regulation of MEF2C in retinal angiogenesis

描述（由申请人提供）：视网膜新生血管（NV）是美国和发达国家致盲的主要原因。血管内皮生长因子（VEGF）在刺激视网膜新生血管形成中起主要作用。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了解相对较少。我们的实验室非常有兴趣阐明重要的转录因子，介导VEGF对视网膜NV的影响。肌细胞增强因子2C（Myocyte enhancer factor 2C，MEF 2C）是一种MADS盒（MCM 1，Agamous，Deficiens，serum response factor-box）转录因子，在血管发育中起重要作用。MEF 2C的靶向缺失导致小鼠严重的血管异常和胚胎致死。我们实验室的初步数据表明MEF 2C在VEGF功能和视网膜血管生成中的重要作用：（1）VEGF以蛋白激酶C（PKC）依赖性方式强烈增加人视网膜内皮细胞（HREC）中的MEF 2C表达;（2）VEGF激活HREC中的MEF 2C功能;（3）在VEGF诱导的趋化性试验中，抑制MEF 2C显著阻断视网膜内皮细胞迁移。我们的总体假设是MEF 2C在视网膜血管生成中在基因表达和功能活性水平上被诱导，并且MEF 2C在介导视网膜血管生成中起重要作用。为了检验我们的假设，我们将使用纯化的人视网膜内皮细胞和视网膜NV的良好表征的小鼠模型（氧诱导的视网膜病变模型）。我们将依次研究MEF 2C基因表达的调节，MEF 2C活性的调节，以及MEF 2C在视网膜血管生成中的功能作用。因此，我们提出以下三个具体目标：具体目标1。检验MEF 2C基因表达在视网膜NV期间受血管生成生长因子调节的假设。具体目标2。检验VEGF通过促进MEF 2C核转位、DNA结合和转录激活调节MEF 2C活性的假设。具体目标3。测试MEF 2C在视网膜NV中起重要功能作用的假设。靶向转录因子作为疾病过程（包括癌症和心力衰竭）的治疗方法正受到越来越多的关注。进一步了解MEF 2C的调节和作用，同样可以为治疗视网膜NV和其他眼部血管生成疾病带来新的治疗策略。

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.