Elucidating the molecular mechanisms that control Muller glia activation in the retina

概述：神经胶质细胞具有非凡的能力，既可以作为中枢神经系统中的分化支持细胞，也可以作为常驻干细胞，在产生新的神经元之前经历去分化和增殖。神经胶质细胞动员成为干细胞样细胞是冷血脊椎动物（外温动物）（如鱼和青蛙）对眼睛生长、损伤或疾病的自然反应。相比之下，神经胶质动员在包括哺乳动物在内的温血脊椎动物（恒温动物）中更为有限。我们研究了小鼠视网膜中的胶质细胞活化，其中Muller胶质细胞（MG）是干细胞的潜在来源。然而，通过MG自愈修复机制的组织再生在吸热动物中不容易发生。相反，MG的青睐的反应是反应性神经胶质增生，神经保护反应，可以伴随细胞毒性effects.To破译哺乳动物MG如何作出选择，要么保持分化的支持细胞，重新进入细胞周期的干细胞，或经历反应性神经胶质增生，我们专注于锌指转录因子Zac1。我们发现MG在Zac1无效突变小鼠中发生损伤非依赖性胶质细胞增生。Zac1是一个母系印记基因，是共调节基因的印记基因网络（IGN）的一部分。因此，我们假设Zac1维持MG处于静止、分化状态，通过IGN起作用以防止反应性神经胶质增生和可能的干细胞修复。为了验证这个假设，我们将：目标1。评估Zac1在维持分化的MG表型中的正常作用。我们评估Zac1功能，在未受伤的眼睛维持分化MG的命运，通过表征Zac1突变MG的命运，并通过评估其响应非损伤诱导cue.Aim 2。研究Zac1在MG损伤反应中的作用。为了确定Zac1是否参与损伤依赖性MG反应，我们评估了Zac1表达对各种应激的反应，并询问Zac1过表达是否对MG具有保护作用。目标3。确定Zac1是否通过IGN起作用以维持成熟MG表型。为了测试Zac1是否通过IGN维持MG处于分化状态，我们研究了IGN基因在Zac1突变MG和损伤模型中的表达，并进行IGN功能测试与功能研究的损失和增益。影响：该项目将提高我们对MG生物学的基础知识，并应用于干细胞生物学和组织再生的一般领域。HQP将接触到创新的，最先进的技术，使他们能够在今天的知识经济中具有竞争力。

Overview: Glial cells have an extraordinary ability to function either as differentiated support cells in the central nervous system, or as resident stem cells, undergoing de-differentiation and proliferation before giving rise to new neurons. Mobilization of glial cells to become stem cell-like is a natural response to eye growth, injury or disease in cold-blooded vertebrates (ectotherms), such as fish and frogs. In contrast, glial mobilization is much more limited in warm-blooded vertebrates (endotherms), including mammals. We study glial cell activation in the murine retina, where Muller glia (MG) are a potential source of stem cells. However, tissue regeneration via a MG self-healing repair mechanism does not occur readily in endotherms. Instead, the favored response of MG to injury in endotherms is reactive gliosis, a neuroprotective response that can have accompanying cytotoxic effects.To decipher how mammalian MG make the choice to either remain as differentiated support cells, re-enter the cell cycle as stem cells, or undergo reactive gliosis, we focus on the zinc finger transcription factor Zac1. We found that MG undergo injury-independent gliosis in Zac1 null mutant mice. Zac1 is a maternally imprinted gene and part of an imprinted gene network (IGN) of co-regulated genes. We thus hypothesize that Zac1 maintains MG in a quiescent, differentiated state, acting via the IGN to prevent reactive gliosis and possibly stem cell-repair. To test this hypothesis we will:Aim 1. Assess the normal role of Zac1 in maintaining a differentiated MG phenotype. We assess Zac1 function in maintaining a differentiated MG fate in the uninjured eye by characterizing the fate of Zac1 mutant MG and by assessing their responsiveness to non-injury inductive cues.Aim 2. Examine the role of Zac1 in the MG injury response. To determine whether Zac1 participates in injury-dependent MG responses, we assess Zac1 expression in response to various stressors, and ask whether Zac1 overexpression is protective in MG. Aim 3. Determine whether Zac1 acts through the IGN to maintain a mature MG phenotype. To test whether Zac1 acts through the IGN to maintain MG in a differentiated state, we study the expression of IGN genes in Zac1 mutant MG and injury models, and perform IGN functional tests with loss- and gain-of-function studies.Impact: This project will enhance our fundamental knowledge of MG biology, with applications to the general field of stem cell biology and tissue regeneration. HQP will be exposed to innovative, state-of-the-art techniques that will allow them to be competitive in today's knowledge-based economy.