Transcriptional Control of Region-Specific Astrocyte Functions in Spinal Cord Circuits

项目摘要 星形胶质细胞对于中枢神经回路的产生、维持和功能是必不可少的。 神经系统（CNS）。我们实验室最近的研究表明，星形胶质细胞表现出广泛的 CNS几个区域的分子和功能多样性。为了理解这个功能是如何 多样性的编码，我们确定了几个转录因子（TF）表现出区域特异性表达。 尽管有这些发现，TF如何促进星形胶质细胞生理学和回路功能在很大程度上仍然存在。 未定义。在表现出区域特异性表达的TF中，我们发现同源框TF Nkx6.1是 仅在成熟脊髓的腹侧星形胶质细胞中表达。Nkx6.1的时间条件性缺失 从成熟星形胶质细胞（Nkx6.1-cKO）中提取的DNA导致腹侧星形胶质细胞的形态复杂性较低 这表明它调节这些星形胶质细胞群体的关键特性。此外，电机 来自Nkx6.1-cKO脊髓的神经元显示胆碱乙酰转移酶表达减少 伴随着VGlut 1突触数量的减少。最后，ChIP-seq分析显示Nkx6.1结合， 并可能调节涉及细胞形态，神经元-星形胶质细胞通讯， 和突触维持。总之，这些结果表明Nkx6.1维持了成熟的星形胶质细胞功能， 对维持脊髓中的突触回路至关重要。因此，我们建议的重点是： 1)确定Nkx6.1如何维持腹侧脊髓星形胶质细胞的形态和生理; 2） 描述Nkx6.1依赖性星形胶质细胞功能如何促进脊髓运动神经元的活动， 运动行为，以及3）确定腹侧脊髓中Nkx6.1控制的独特转录机制 脊髓星形胶质细胞

PROJECT SUMMARY Astrocytes are essential for the generation, maintenance, and function of neuronal circuits in the central nervous system (CNS). Recent studies from our laboratory revealed that astrocytes exhibit extensive molecular and functional diversity across several regions of the CNS. To understand how this functional diversity is encoded, we identified several transcription factors (TFs) that exhibit region-specific expression. Despite these findings, how TFs contribute to astrocyte physiology and circuit function remain largely undefined. Among the TFs exhibiting region-specific expression, we found that the homeobox TF Nkx6.1 is expressed exclusively in ventral astrocytes of the mature spinal cord. Temporal-conditional deletion of Nkx6.1 from mature astrocytes (Nkx6.1-cKO) resulted in a lower morphological complexity of astrocytes in the ventral spinal cord suggesting that it regulates key properties of these astrocyte populations. Additionally, motor neurons from Nkx6.1-cKO spinal cords demonstrate reduced expression of choline acetyltransferase accompanied by reduced number of VGlut1 synapses. Finally, ChIP-seq analysis shows that Nkx6.1 binds, and possibly regualtes the expression of genes involved in cell morphology, neuron-astrocyte communication, and synaptic maintenance. Together, these results suggest that Nkx6.1 maintains mature astrocyte functions that are essential for the maintenance of synaptic circuits in the spinal cord. Thus, the focus of our proposal is: 1) to determine how Nkx6.1 maintains morphology and physiology of ventral spinal cord astrocytes; 2) to delineate how Nkx6.1-dependent astrocyte functions contribute to the activity of spinal cord motor neurons and motor behaviors, and 3) to define the unique transcriptional mechanism controlled by Nkx6.1 in ventral spinal cord astrocytes.