Novel Modulators of TGFß1 signaling in regulation of remyelination by neural stem cells

摘要 少突胶质细胞的丢失会引起脱髓鞘，最终导致轴突退化和衰弱。 多发性硬化症等疾病的临床结果。虽然重新髓鞘化能防止神经退化，但 目前还没有被批准的促进髓鞘再生的疗法。因此，迫切需要确定各种因素。 控制重新髓鞘形成的物质。成人室下区的神经干细胞是 少突胶质细胞重新髓鞘形成。这些细胞是一个不同的群体，对 健康与脱髓鞘大脑中的信号通路。我们已经研究了一个这样的池，标记为Gli1，它 仅在脱髓鞘时产生重新髓鞘的少突胶质细胞。我们之前的工作表明， 募集和分化为少突胶质细胞导致功能恢复显著增加 Gli1在这个神经干细胞池中丢失；然而，参与这种修复的分子机制并不是 为人所知。通过转录分析比较有无Gli1基因在神经干细胞中的表达 表达，我们发现转化生长因子β1通路是神经干细胞介导的髓鞘再生的主要调节因子。 细胞。然而，转化生长因子β-1信号转导的影响是上下文相关的，并且随细胞类型、时间和 剂量表明在不同的细胞中存在该途径的特定调节物。使用以下组合 在小鼠的生物信息学分析和髓鞘再分化研究中，我们发现了转化生长因子β1途径的一个新的介体， 神经干细胞脱髓鞘反应中高表达的GPNMB及其受体CD44。 在第一个目标中，我们将定义GPNMB在神经干细胞中的细胞自主功能及其在 神经干细胞的重新髓鞘形成。在第二个目标中，我们将确定旁分泌GPNMB信号的影响 通过CD44受体对神经干细胞介导的再髓鞘形成的影响。在第三个目标中，我们将阐明 转化生长因子β-1配体调节GPNMB及相互调节转化生长因子β-1途径的机制 GPNMB。对于髓鞘再分化的研究，我们将使用毒素诱导的脱髓鞘模型。要定义 转化生长因子β1-GPNMB信号通路的分子机制，我们将利用体外神经干细胞培养 取自成年小鼠的大脑。总之，这些研究将有助于确定促进髓鞘再生的治疗靶点。

ABSTRACT Loss of oligodendrocytes gives rise to demyelination, ultimately resulting in axonal degeneration and debilitating clinical outcomes in diseases like Multiple Sclerosis. While remyelination can prevent neurodegeneration, there are currently no approved therapies for promoting remyelination. Thus, there is an urgent need to identify factors that control remyelination. Neural stem cells in the adult subventricular zone are one of the sources of remyelinating oligodendrocytes. These cells are a heterogeneous population that show diverse responses to signaling pathways in the healthy vs demyelinated brain. We have studied one such pool marked by Gli1, which generates remyelinating oligodendrocytes only in response to demyelination. Our previous work showed that the recruitment and differentiation into oligodendrocytes leading to functional recovery is increased substantially by loss of Gli1 in this pool of neural stem cells; however the molecular mechanisms involved in this repair is not known. Through a transcriptomic analysis comparing gene expression in neural stem cells with and without Gli1 expression, we identified the TGFβ1 pathway as a major regulator of remyelination mediated by neural stem cells. However, the effects of TGFβ1 signaling are context dependent and differ with the cell-type, timing and dosage suggesting the presence of specific modulators of the pathway in different cells. Using a combination of bioinformatic analysis and remyelination studies in mice, we discovered a novel mediator of the TGFβ1 pathway, Gpnmb which is highly expressed along with its receptor CD44 in neural stem cells in response to demyelination. In the first aim, we will define the cell-autonomous function of Gpnmb in neural stem cells and its role in remyelination by neural stem cells. In the second aim, we will determine the impact of paracrine Gpnmb signaling through CD44 receptor on remyelination mediated by neural stem cells. In the third aim, we will elucidate the mechanisms of regulation of Gpnmb by TGFβ1 ligand and reciprocal modulation of the TGFβ1 pathway by Gpnmb. For the remyelination studies, we will use the toxin induced models of demyelination. To define the molecular mechanisms of the TGFβ1-Gpnmb signaling pathway, we will utilize in vitro neural stem cell cultures from adult mouse brain. Together, these studies will help identify therapeutic targets for promoting remyelination.