Ensheathing glia function as phagocytes in the adult Drosophila brain.
Ensheathing glia function as phagocytes in the adult Drosophila brain.
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DOI：
10.1523/jneurosci.5951-08.2009
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发表时间：
2009-04-15
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影响因子：
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通讯作者：
Freeman MR
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文献类型：
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作者：
Doherty J;Logan MA;Taşdemir OE;Freeman MR
哺乳动物脑中含有许多胶质细胞亚型，其形态、基因表达谱和功能作用各不相同;然而，成年果蝇脑中胶质细胞的功能多样性仍然不清楚。在这里，我们定义的神经胶质亚型的多样性，存在于成年果蝇的大脑，显示他们承担惊人的相似性，哺乳动物的大脑胶质细胞，并确定主要的吞噬细胞类型负责吞噬变性轴突急性轴突切断后。我们发现，神经胶质细胞区域包含两个不同的群体：成鞘胶质细胞和星形胶质细胞。成鞘胶质细胞包裹成人大脑中的主要结构，但与突触没有密切联系。有趣的是，我们发现这些胶质细胞独特地表达胶质细胞吞噬机制的关键组分（例如，吞噬受体德雷珀和dCed-6），对轴突损伤作出形态学反应，并且自主地需要德雷珀信号通路的组分以成功地从损伤的大脑中清除退化的轴突。相反，星形胶质细胞不表达德雷珀或dCed-6，对轴突损伤没有形态学反应，并且似乎在从脑中清除变性轴突方面没有作用。然而，星形胶质细胞胶质细胞与神经元中的突触区域密切相关，并表达兴奋性氨基酸转运蛋白，这可能是清除突触间隙中过量神经递质所需的。总之，这些结果表明，成鞘神经胶质细胞和星形胶质细胞是预先编程的细胞类型在成年果蝇脑，与成鞘神经胶质细胞作为吞噬细胞轴突切开后，和星形胶质细胞可能调节突触的形成和信号。
The mammalian brain contains many subtypes of glia that vary in their morphologies, gene expression profiles, and functional roles; however the functional diversity of glia in the adult Drosophila brain remains poorly defined. Here we define the diversity of glial subtypes that exist in the adult Drosophila brain, show they bear striking similarity to mammalian brain glia, and identify the major phagocytic cell type responsible for engulfing degenerating axons after acute axotomy. We find that neuropil regions contain two different populations of glia: ensheathing glia and astrocytes. Ensheathing glia enwrap major structures in the adult brain, but are not closely associated with synapses. Interestingly, we find these glia uniquely express key components of the glial phagocytic machinery (e.g. the engulfment receptor Draper, and dCed-6), respond morphologically to axon injury, and autonomously require components of the Draper signaling pathway for successful clearance of degenerating axons from the injured brain. Astrocytic glia, in contrast, do not express Draper or dCed-6, fail to respond morphologically to axon injury, and appear to play no role in clearance of degenerating axons from the brain. However, astrocytic glia are closely associated with synaptic regions in neuropil, and express excitatory amino acid transporters, which are presumably required for the clearance of excess neurotransmitters at the synaptic cleft. Together these results argue that ensheathing glia and astrocytes are preprogrammed cell types in the adult Drosophila brain, with ensheathing glia acting as phagocytes after axotomy, and astrocytes potentially modulating synapse formation and signaling.