Regenerative potential of retinal Muller glial cells

描述(申请人提供)：这项研究计划的目标是确定哺乳动物视网膜通过内源性机制进行修复的潜力。作为对视网膜损伤的反应，几种脊椎动物模型系统的Muller胶质(MG)细胞被证明能长出新的视网膜神经元。然而，在哺乳动物中，直接测试MG细胞在体内再生能力的数据很少。我们的中心假设是，作为对视网膜损伤的反应，成熟的小鼠MG细胞具有重新进入细胞周期并转分化为视网膜神经元的能力。这项提议的总体目标是通过进行遗传、Cre-loxP命运图谱实验和时间推移成像来检验这一假说。目的1.测定小鼠Muller神经胶质细胞在特定环境条件下分化为成熟视网膜神经元的能力。我们将通过化学诱导神经元变性和在体内进行Cre-loxP命运映射实验来检验视网膜Muller胶质(MG)细胞具有再生视网膜神经元的能力的假设。我们还将测试这一假设，即由于胶质瘢痕形成的不允许的视网膜环境，MG细胞的再生潜力受到显着阻碍。在这里，我们将执行相同的命运映射实验，但在Vimentin-/-；GFAP-/-突变小鼠的遗传背景下，已知表现出更支持神经元移植的视网膜环境。目的2.阐明Muller神经胶质细胞对视网膜损伤和随后的转分化事件的反应的细胞机制。我们假设，作为对损伤的反应，MG细胞的一个离散的子集重新进入细胞周期，并向视网膜的外界膜顶端移位，在那里它们经历有丝分裂，然后移位到适当的板层作为分化神经元。为了验证这一假设，我们将对损伤诱导的视网膜外植体进行实时成像，其中MG细胞被荧光标记。神经元变性是一系列人类认知和运动疾病的核心，包括阿尔茨海默氏症和帕金森氏症，以及诸如失明等感觉性疾病。通过表征视网膜内有能力产生新神经元的细胞群体，治疗方法可以被用来利用这些细胞的能力来治愈人类神经疾病。

DESCRIPTION (provided by applicant): The objective of this research proposal is to determine the potential of the mammalian retina for repair via endogenous mechanisms. In response to retinal damage, Muller glial (MG) cells of several vertebrate model systems have been shown to give rise to new retinal neurons. However, in mammals, there is a paucity of data directly testing the regenerative capacity of MG cells in vivo. Our central hypothesis is that, in response to retinal damage, mature mouse MG cells possess the ability to re-enter the cell cycle and trans-differentiate into retinal neurons. The overall goal of this proposal is to test this hypothesis by performing genetic, Cre-loxP fate mapping experiments and time lapse imaging. Aim 1. Determine the capacity of mouse Muller glial cells to give rise to mature retinal neurons within specific environmental contexts. We will test the hypothesis that retinal Muller glial (MG) cells have the ability to regenerate retinal neurons by chemically inducing neuronal degeneration and performing in vivo Cre-loxP fate-mapping experiments. We will also test the hypothesis that MG cell regenerative potential is significantly hindered as a consequence of a non-permissive retinal environment due to glial scarring. Here, we will perform the same fate-mapping experiment, but within the genetic background of Vimentin-/-; Gfap-/- mutant mice known to exhibit a retinal environment substantially more supportive of neuronal transplantation. Aim 2. Elucidate the cellular mechanisms of the Muller glial response to retinal damage and subsequent trans-differentiation events. We hypothesize that, in response to damage, a discrete subset of MG cells re-enter the cell cycle and translocate apically toward the outer limiting membrane of the retina where they undergo mitosis before translocating to the appropriate lamina as differentiating neurons. To test this hypothesis, we will perform live imaging of damage-induced retinal explants in which MG cells are fluorescently labeled. RELEVANCE Neuronal degeneration lies at the heart of a spectrum of debilitating human cognitive and motor diseases including Alzheimer's and Parkinson's disease as well as sensory diseases such as blindness. By characterizing cell populations within the retina, which have the ability to generate new neurons, therapeutic approaches could be employed to harness the ability of these cells to cure human neurological diseases.