Regeneration of rod photoreceptors from Muller glial cells in adult mouse retina

 描述（由申请方提供）：Müller胶质细胞（MG）是脊椎动物视网膜中的主要支持细胞。在冷血脊椎动物如斑马鱼中，MG是干细胞的来源，因为它们可以很容易地重新进入细胞周期并补充失去的神经元，建立强大的自我修复机制。然而，在哺乳动物中，MG是天然静止的，缺乏再生能力。光感受器是哺乳动物视网膜中最丰富的细胞，它们介导视觉的第一步。光感受器的死亡是主要视网膜变性疾病（包括年龄相关性黄斑变性（AMD）和视网膜色素变性（RP））中视力受损和失明的主要原因。旨在恢复哺乳动物MG再生能力的广泛研究努力几乎没有成功。目前MG衍生的感光细胞再生的策略依赖于视网膜损伤和用各种因素治疗整个视网膜。视网膜损伤首先会杀死视网膜神经元。整个视网膜的整体治疗可能导致非靶向细胞的不良副作用。我们研究的长期目标是了解MG衍生的光感受器再生的分子和细胞途径，并制定策略来激活哺乳动物MG的视网膜自我修复再生能力。我们提出在体内重编程成年小鼠MG，用于在没有视网膜损伤的情况下再生视杆光感受器，通过以下目的：目的1）研究Wnt信号传导是否是激活MG增殖的损伤诱导的信号传导途径。我们将研究神经毒性损伤是否激活Wnt信号传导，并进一步测试Wnt信号传导的抑制是否抑制损伤诱导的MG增殖。为了靶向MG细胞类型特异性，我们将开发靶向MG细胞类型特异性的基因转移方法。目的2）通过激活Wnt信号通路恢复MG的视网膜祖细胞/干细胞状态，而不引入视网膜损伤。我们将研究β-catenin的基因转移是否在没有视网膜损伤的情况下激活Wnt信号传导和MG增殖。GSk 3 β通过β-catenin的磷酸化导致其降解来调节Wnt信号传导。我们将检查GSK 3 β的缺失是否激活Wnt信号传导和MG增殖而不损伤视网膜。目的3）诱导MG源性视网膜前体细胞/干细胞向视杆细胞分化 光感受器我们将通过转录因子的基因转移来指导MG衍生的视网膜祖细胞/干细胞的分化，这些转录因子对于视网膜发育过程中视杆细胞的命运决定和分化至关重要，并测试MG衍生的新视杆细胞是否具有天然视杆细胞的分子、结构和功能特性。我们提出的研究将显着推进我们的了解MG衍生的视杆细胞再生在成年哺乳动物视网膜的基本机制和功能的影响，并将设置阶段视网膜自我修复在一个主要的视网膜退行性疾病的特点是感光细胞变性。

 DESCRIPTION (provided by applicant): Müller glial cells (MGs) are the primary support cells in the vertebrate retina. In cold-blooded vertebrates such as zebrafish, MGs are a source of stem cells for they can readily re-enter the cell cycle and replenish lost neurons, establishing a powerful self-repair mechanism. In mammals, however, MGs are naturally quiescent and lack regenerative capability. Photoreceptors are the most abundant cells in the mammalian retina and they mediate the first step in vision. The death of photoreceptors is a leading cause of vision impairment and blindness in major retinal degenerative diseases including age-related macular degeneration (AMD) and retinitis pigmentosa (RP). Extensive research efforts aimed at restoring the regenerative capability of MGs in mammals have met with little success. Current strategies for MG-derived photoreceptor regeneration rely on retinal injury and treatment of the whole retina with various factors. Retinal injury kills retinal neurons in the first place. Global treatment of the entire retina may lead to undesirable side effects in untargeted cells. The long-term goal of our research is to understand the molecular and cellular pathways underlying MG-derived photoreceptor regeneration, and to develop strategies to activate the regenerative capability of mammalian MGs for retinal self-repair. We propose to reprogram adult mouse MGs, in vivo, for regeneration of rod photoreceptors without retinal injury, through the following Aims: Aim 1) Investigate whether Wnt signaling is an injury-induced signaling pathway to activate MG proliferation. We will examine whether neurotoxic injury activates Wnt signaling and further test whether inhibition of Wnt signaling suppressed injury-induced MG proliferation. To target MGs cell-type-specifically, we will develop a gene transfer method targeting MGs cell-type-specifically. Aim 2) Restore the retinal progenitor/stem cell status of MGs through activation of Wnt signaling, without introduction of retinal injury. We will investigate whether gene transfer of β-catenin activates Wnt signaling and MG proliferation without retinal injury. GSk3β regulates Wnt signaling by phosphorylation of β-catenin leading to its degradation. We will examine whether deletion of GSK3β activates Wnt signaling and MG proliferation without retinal injury. Aim 3) Guide the differentiation of MG-derived retinal progenitor/stem cells to rod photoreceptors. We will guide the differentiation of MG-derived retinal progenitor/stem cells by gene transfer of transcription factors that are essential for rod photoreceptor cell fate determination and differentiation during retinal development, and test whether MG-derived new rods develop molecular, structural, and functional properties of native rods. Our proposed research will significantly advance our understanding of the basic mechanisms and functional implications of MG-derived rod photoreceptor regeneration in adult mammalian retina, and will set the stage for retinal self-repair in a major group of retinal degenerative diseases typically characterized by photoreceptor degeneration.