HDAC4-mediated Photoreceptor Protection in Retinal Degeneration

项目摘要/摘要： 在美国，导致失明的主要原因是视网膜变性，通常与死亡有关 光感受器(视杆和视锥)。摘要视网膜色素变性是遗传性视网膜病变的主要类型。 通常由杆状特异基因突变引起的退行性疾病。这些基因缺陷导致 杆状细胞死亡，随后正常球果逐渐退化。正是锥体死亡导致了渐进性视力 在RP中的损失。在美国，目前有超过10万人受到RP的影响，没有任何治疗或预防措施 可用。我们的长期目标是了解RP的光感受器变性的机制，并 开发挽救光感受器和恢复RP患者视觉功能的治疗方法。面临的一个重大挑战 挽救杆状病毒是RP的异质性，因为已经在杆状病毒特异基因中发现了许多突变； 因此，每种突变都可能需要一种独特的治疗方法。相比之下，节省圆锥体可能会提供更一般的 为快速成型节省视力的方法。我们先前的研究证明了HDAC4在促进杆状突起中的新作用 在RP小鼠模型中存活。我们将通过以下目标扩大我们的研究范围：目标1)我们将 研究HDAC4保护视网膜光感受器的分子和细胞机制 退化的小鼠。使用cre-loxP系统限制HDAC4在特定细胞类型中的表达，我们将测试 HDAC4是否通过细胞自主机制在光感受器中发挥促进生存的作用 HDAC4在其他细胞类型中有S效应。我们将进一步测试HDAC4去乙酰基酶结构域是否需要 它在光感受器保护中的作用。目的2)我们将测试HDAC4是否在FAST和 较慢的视网膜变性模型。用腺相关病毒(AAV)介导的Rd1小鼠(A)的基因转移 快速视网膜变性模型)，我们将测试HDAC4是否直接促进视锥细胞存活。我们将测试 保存的锥体结构和锥体光传导中的关键成分。利用AAV介导的基因 在VPP和RD10小鼠(较慢的视网膜变性模型)中的转移，我们将调查1)是否 光感受器保护需要HDAC4的发育表达；2)HDAC4是否可以用作 光感受器保护的更普遍的生存因素。目标3)我们将研究主要的生存信号 在视网膜退化期间失活的通路，在HDAC4保存的视锥细胞中重新激活。我们会 进一步测试HDAC4保存的视锥细胞是否恢复了视觉功能：1)电生理学测试完整性 视网膜和视皮层的神经回路；2)行为测试，以确定是否挽救了视网膜 功能可以指导复杂的行为。总而言之，我们提议的研究将阐明分子和 HDAC4促进光感受器存活的细胞机制和途径 视网膜遗传性疾病的靶点。我们提出的HDAC4在这两种情况下促进生存的研究 视杆和视锥细胞将推进一大类致盲疾病的治疗模式。

Project Summary/Abstract: The leading cause of blindness in the United States is retinal degeneration, typically involving the death of photoreceptors (rods and cones). Retinitis pigmentosa (RP) refers to a major group of hereditary retinal degenerative diseases commonly caused by mutations in rod-specific genes. These genetic defects cause rods to die followed by gradual degeneration of normal cones. It is cone death that results in progressive vision loss in RP. RP affects over 100,000 people in the United States with no treatment or prevention currently available. Our long-term goal is to understand the mechanism of photoreceptor degeneration in RP and to develop therapies that save photoreceptors and restore visual function in RP patients. A major challenge to saving rods is the heterogeneous nature of RP, as many mutations have been identified in rod-specific genes; thus, each mutation may require a unique therapy. By contrast, saving cones may provide a more general means to save vision for RP. Our previous study demonstrated a novel role of HDAC4 in promoting rod survival in a mouse model of RP. We will expand our studies through the following Aims: Aim 1) we will investigate the molecular and cellular mechanisms through which HDAC4 protects photoreceptors in retinal degeneration mice. Using a cre-loxp system to restrict HDAC4 expression in specific cell types, we will test whether HDAC4 exerts its pro-survival effect in photoreceptors through a cell-autonomous mechanism versus HDAC4's effect in other cell types. We will further test whether the HDAC4 deacetylase domain is required for its effect in photoreceptor protection. Aim 2) we will test whether HDAC4 saves photoreceptors in both fast and slower retinal degeneration models. Using AAV(adeno-associated virus)-mediated gene transfer in rd1 mice (a fast retinal degeneration model), we will test whether HDAC4 directly promotes cone survival. We will test for preserved cone structure and critical components in cone phototransduction. Using AAV-mediated gene transfer in VPP and rd10 mice (slower retinal degeneration models), we will investigate 1) whether photoreceptor protection requires developmental expression of HDAC4; 2) whether HDAC4 can be used as a more general survival factor for photoreceptor protection. Aim 3) we will investigate major survival signaling pathways that are inactivated during retinal degeneration and reactivated in HDAC4-saved cones. We will further test whether HDAC4-saved cones restore visual function using: 1) electrophysiology to test the integrity of neural circuits in the retina and visual cortex; 2) behavioral tests to determine whether rescued retinal function can guide complex behaviors. In summary, our proposed studies will elucidate the molecular and cellular mechanisms and pathways through which HDAC4 promotes the survival of photoreceptors, the main target of genetic diseases in the retina. Our proposed research on the pro-survival effect of HDAC4 in both rods and cones will advance the therapeutic paradigm for a major group of blinding diseases.