HDAC4-mediated Photoreceptor Protection in Retinal Degeneration

项目概要/摘要： 在美国失明的主要原因是视网膜变性，通常涉及死亡 光感受器（视杆细胞和视锥细胞）。视网膜色素变性（RP）是指一组主要的遗传性视网膜色素变性。 退化性疾病通常是由杆状病毒特异性基因突变引起的。这些基因缺陷导致 视杆细胞死亡，随后正常视锥细胞逐渐退化。正是视锥细胞死亡导致了视力的进步 RP的损失。RP在美国影响超过10万人，目前没有治疗或预防 available.我们的长期目标是了解RP中感光细胞变性的机制， 开发拯救光感受器和恢复RP患者视觉功能的疗法。的一大挑战 保存视杆细胞是RP的异质性，因为在视杆细胞特异性基因中已经鉴定出许多突变; 因此，每个突变可能需要独特的治疗。相比之下，保存锥体可以提供更一般的 这意味着为RP保存视力。我们先前的研究表明HDAC 4在促进视杆细胞增殖中具有新的作用， RP小鼠模型中的存活率。我们将通过以下目标扩大我们的研究：目标1）我们将 研究HDAC 4保护视网膜光感受器的分子和细胞机制。 变性小鼠使用cre-loxp系统限制HDAC 4在特定细胞类型中的表达，我们将测试 HDAC 4是否通过细胞自主机制在光感受器中发挥其促存活作用， HDAC 4在其他细胞中的作用我们将进一步测试HDAC 4脱乙酰基酶结构域是否是 其在光感受器保护中的作用。目的2）我们将测试HDAC 4是否在快速和快速两种情况下保存光感受器。 更慢的视网膜变性模型。在rd 1小鼠中使用AAV（腺相关病毒）介导的基因转移（a 快速视网膜变性模型），我们将测试HDAC 4是否直接促进视锥细胞存活。我们将测试 保留了视锥结构和视锥光转导中的关键组分。使用AAV介导的基因 在VPP和rd 10小鼠（较慢的视网膜变性模型）中转移，我们将研究1）是否 光感受器保护需要HDAC 4的发育表达; 2）HDAC 4是否可以用作 更普遍的感光细胞保护的生存因素。目标3）我们将研究主要的生存信号 在视网膜变性过程中失活并在HDAC 4保存的视锥细胞中重新激活的通路。我们将 进一步测试HDAC 4保存的视锥细胞是否恢复视觉功能，使用：1）电生理学以测试完整性 视网膜和视觉皮层的神经回路; 2）行为测试，以确定是否挽救视网膜 功能可以指导复杂的行为。总之，我们提出的研究将阐明分子和 HDAC 4通过细胞机制和途径促进光感受器的存活，主要是 视网膜中遗传疾病的靶点。我们提出的研究HDAC 4在两种细胞中的促生存作用， 视杆细胞和视锥细胞的研究将推动一大类致盲性疾病的治疗模式。

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.