Neuroprotection Mechanism for Photoreceptors

 描述(申请人提供)：睫状神经营养因子(CNTF)在多种视网膜变性动物模型中作为一种有效的神经保护剂。近年来，从胶囊细胞装置中分泌的CNTF已经在几个临床试验中进行了评估，FDA已批准这种CNTF疗法为孤儿药物，用于治疗视网膜色素变性(RP)和干性年龄相关性黄斑变性(AMD)。然而，尽管CNTF作为不同致盲疾病的广谱治疗剂具有潜力，但其在视网膜中的作用机制仍然知之甚少。我们以前已经证明，结构性的、高水平的CNTF表达可以防止光感受器死亡，但会改变视网膜基因的表达，并抑制视觉功能。最近，我们在RP小鼠模型中用临床试验中使用的相同的人CNTF治疗，利用遗传扰动来探索CNTF的作用机制。通过进行视网膜细胞类型特异性基因的删除，我们发现CNTF的初始靶点是Müler神经胶质细胞，如果Müler神经胶质细胞中没有功能性的细胞因子受体，下游信号事件和CNTF诱导的光感受器存活就会被取消。虽然杆状感光器不直接对外源性CNTF产生反应，但它们也需要有功能的细胞因子受体才能存活。此外，我们还提供了外源性CNTF刺激和放大Müler神经胶质细胞和光感受器之间的信号环路以促进神经元存活的证据。然而，尽管光感受器的形态和活性有了显著的改善，但低水平的外源性CNTF只会稳定下来，而不会进一步增强视网膜功能。这项拟议的研究将结合先进的分子遗传学和系统生物学方法来研究CNTF诱导视网膜神经保护的机制。我们将通过使用转基因小鼠来确定CNTF激活的特定信号通路在视杆状感光细胞和Müler神经胶质细胞中的功能。我们将通过比较野生型和突变型视网膜来分析CNTF在视杆细胞表观基因组和转录组水平上的变化，以破译影响细胞生存和功能的关键细胞过程。我们还将评估CNTF治疗对病变视网膜细胞代谢的影响，并确定介导这一效应的信号效应因子。这项研究将促进我们对神经保护机制的理解，深入了解CNTF在人类视网膜中的作用，并促进开发更有效的治疗视网膜变性的方法。

 DESCRIPTION (provided by applicant): Ciliary neurotrophic factor (CNTF) acts as a potent neuroprotective agent in a variety of retinal degeneration animal models. In recent years, CNTF secreted from an encapsulated cell device has been evaluated in several clinical trials, and the FDA has granted this CNTF therapy an Orphan Drug Status for the treatment of retinitis pigmentosa (RP) and dry age-related macular degeneration (AMD). Yet despite the potential of CNTF as a broad-spectrum therapeutic agent for different blinding diseases, its mechanisms of action in the retina remain poorly understood. We have shown previously that constitutive, high-level expression of CNTF prevents photoreceptor death but alters retinal gene expression and suppresses visual function. Recently, we have explored the mechanism of CNTF action using genetic perturbations in an RP mouse model treated with the same human CNTF used in clinical trials. By performing retinal cell type specific gene deletions, we have shown that the initial targets of CNTF are Müller glial cells, and without a functional cytokine receptor in Müler glia, downstream signaling events and CNTF-induced photoreceptor survival are abolished. Although the rod photoreceptors do not directly respond to exogenous CNTF, they also require a functional cytokine receptor for survival. Furthermore, we have provided evidence that exogenous CNTF stimulates and amplifies a signaling loop between Müller glia and photoreceptors to promote neuronal viability. However, despite a significant improvement in photoreceptor morphology and viability, low levels of exogenous CNTF only stabilize but do not further enhance retinal function. The proposed research will combine advanced molecular genetics and system biology approaches to investigate the mechanisms underlying CNTF-induced neuroprotection in the retina. We will determine the functions of specific signaling modalities activated by CNTF in rod photoreceptors and Müller glia by using genetically modified mice. We will analyze CNTF-induced changes at the epigenome and transcriptome levels in rod cells by comparing wild type and mutant retinas to decipher critical cellular processes affecting cell survival and function. We will also evaluate the effect of CNTF treatment on cellular metabolism in diseased retinas and define the signaling effector mediating the effect. The proposed research will advance our understanding of neuroprotection mechanisms, provide insight into the effects of CNTF in human retinas, and facilitate the development of more efficacious treatments for retinal degeneration.