Neuronal responses to chronic demyelination

项目总结 少突胶质细胞是一种高度专业化的神经胶质细胞，它使脊椎动物中枢神经系统的轴突髓鞘，两者 通过跳跃传导促进神经冲动的快速传递，并提供代谢和营养 对轴突的支持。该领域的一种普遍观点认为，这种少突胶质细胞的丧失 支持(如多发性硬化症等脱髓鞘疾病)直接导致轴突丢失和 累积伤残。然而，需要少突胶质细胞支持的直接实验证据 轴突存活在很大程度上是缺乏的。此外，关于神经元是如何 对主要的脱髓鞘侮辱做出回应。为了更好地了解少突胶质细胞支持的丧失 轴突直接导致轴突丢失或神经元改变，我们将利用两种三苯氧胺诱导 Myrf基因的条件性敲除小鼠品系，该基因编码一种转录因子， 髓鞘形成和髓鞘维护。MYRF∆iPLP小鼠系导致少突胶质细胞丢失和严重中枢神经系统 脱髓鞘，但很大程度上是通过招募非重组的OPC重新髓鞘。相比之下， MYRF∆iSox10小鼠表现出几乎完全的中枢神经系统脱髓鞘并重新髓鞘形成失败，代表着 独特的严重慢性脱髓鞘小鼠模型。 根据我们的初步数据，我们假设神经元最初对严重的脱髓鞘具有弹性 侮辱，但面对随后的髓鞘再分化失败、炎症或 新陈代谢挑战。此外，我们还发现DLK/JNK/c-jun轴突应激通路在 慢性脱髓鞘动物，提供了一个潜在的分子信号，将慢性脱髓鞘与 神经退行性变。我们将使用这些小鼠的视网膜神经节细胞(RGC)作为理想的有髓神经元 人群：1)确定重新髓鞘形成失败、神经炎症和代谢的相对作用 诱导神经变性的挑战；2)确定DLK/JNK/c-Jun在神经元中的中介作用 少突胶质细胞失去支持后的变化以及3)使用散装和单细胞RNA-Seq来确定 视网膜节细胞在胶质细胞支持丧失时的转录变化并确定其特异性 视网膜节细胞亚群对脱髓鞘表现出优先易感性。

PROJECT SUMMARY Oligodendrocytes are a highly specialized type of glial cell that myelinates axons of the vertebrate CNS, both promoting rapid transmission of nerve impulses via saltatory conduction and providing metabolic and trophic support for the axons. A widely held consensus view in the field holds that the loss of this oligodendrocyte support (as seen in demyelinating conditions such as multiple sclerosis) directly contributes to axonal loss and cumulative disability. Nevertheless, direct experimental evidence for oligodendrocyte support being required for axonal survival is largely lacking. In addition, there is remarkably little information available on how neurons respond to a primary demyelinating insult. To better understand whether loss of oligodendrocyte support of axons directly leads to axonal loss or neuronal changes, we will capitalize on two tamoxifen-inducible conditional knockout mouse strains for the Myrf gene, which encodes a transcription factor required for myelination and myelin maintenance. The Myrf∆iPLP mouse line leads to oligodendrocyte loss and severe CNS demyelination, but largely remyelinates through recruitment of non-recombined OPCs. In contrast, the Myrf∆iSox10 mouse line shows near complete CNS demyelination with remyelination failure, representing a unique mouse model of severe and chronic demyelination. Based on our preliminary data we hypothesize that neurons are initially resilient to even severe demyelinating insults, but that they become vulnerable to loss in the face of subsequent remyelination failure, inflammation or metabolic challenge. In addition, we have found activation of the DLK/JNK/c-Jun axonal stress pathway in chronically demyelinated animals, providing a potential molecular signal linking chronic demyelination to neurodegeneration. We will use retinal ganglion cells (RGCs) in these mice as the ideal myelinated neuronal population to: 1) determine the relative roles of remyelination failure, neuroinflammation and metabolic challenge in inducing neurodegeneration; 2) establish the role of the DLK/JNK/c-Jun in mediating neuronal changes following loss of oligodendrocyte support and 3) Use bulk and single cell RNA-Seq to determine the transcriptional changes in RGCs in response to loss of glial support and to determine whether specific subgroups of RGCs show preferential vulnerability to demyelination.