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

摘要 少突胶质细胞的损失会导致脱髓鞘，最终导致轴突变性和衰弱 多发性硬化症等疾病的临床结果。虽然髓鞘再生可以预防神经退行性变，但 目前尚无批准的促进髓鞘再生的疗法。因此，迫切需要找出影响因素 控制髓鞘再生。成人脑室下区的神经干细胞是神经干细胞的来源之一。 髓鞘再生少突胶质细胞。这些细胞是异质群体，对不同的反应表现出不同的反应 健康大脑与脱髓鞘大脑中的信号通路。我们研究了这样一个由 Gli1 标记的池，它 仅在脱髓鞘反应中产生髓鞘再生少突胶质细胞。我们之前的工作表明 少突胶质细胞的募集和分化导致功能恢复显着增加 该神经干细胞库中 Gli1 缺失；然而，参与这种修复的分子机制并不 已知。通过转录组分析比较有和没有 Gli1 的神经干细胞中的基因表达 表达，我们确定 TGFβ1 途径是神经干介导的髓鞘再生的主要调节因子 细胞。然而，TGFβ1 信号传导的影响取决于环境，并且因细胞类型、时间和作用而异。 剂量表明不同细胞中存在该途径的特定调节剂。使用组合 通过对小鼠的生物信息分析和髓鞘再生研究，我们发现了一种新型的 TGFβ1 通路介质， Gpnmb 与其受体 CD44 一起在神经干细胞中高度表达，以响应脱髓鞘作用。 第一个目标是定义 Gpnmb 在神经干细胞中的细胞自主功能及其在神经干细胞中的作用。 神经干细胞的髓鞘再生。在第二个目标中，我们将确定旁分泌 Gpnmb 信号传导的影响 通过CD44受体介导神经干细胞的髓鞘再生。在第三个目标中，我们将阐明 TGFβ1配体调节Gpnmb的机制以及TGFβ1途径的相互调节 GPnmb。对于髓鞘再生研究，我们将使用毒素诱导的脱髓鞘模型。定义 TGFβ1-Gpnmb 信号通路的分子机制，我们将利用体外神经干细胞培养物 来自成年小鼠的大脑。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.