Loss of Jedi-1 impairs microglia phagocytosis, resulting in reduced postnatal neurogenesis in the ventricular-subventricular zone.

项目摘要 JEDI-1是一种吞噬受体，通过卫星介导吞噬细胞清除凋亡的感觉神经元 发育中的小鼠周围神经系统中的神经胶质细胞。细胞凋亡碎片的清除也对 中枢神经系统(CNS)的发育和维持，尤其是在出生后 神经发生。神经发生依赖于神经干细胞/祖细胞(NSPC)增殖的耦合， 新生神经细胞凋亡，并清除凋亡碎片。关键的是，吞噬功能的丧失阻碍了 神经发生。免疫荧光标记技术在雄性和雌性野生型(WT)脑切片中的应用 和绝地-1基因敲除小鼠(JKO)在出生后的第一周，我们发现绝地-1在WT中表达 小胶质细胞存在于出生后神经源性壁龛，即室-室下区(V-SVZ)，但在 淘汰赛。因此，我们询问了小胶质细胞中JEDI-1的表达是否有助于这种偶联和 从而调节神经发生。为了测试绝地-1的缺失是否会阻碍小胶质细胞的吞噬能力，我们 采用了体外吞噬试验，发现JKO小胶质细胞显示出显著的减少 相对于WT小胶质细胞的吞噬。这一发现被概括为在脑内积累的凋亡细胞 TUNEL法检测JKO V-SVZ的表达。以确定绝地一号的损失和随后的中断 小胶质细胞吞噬能力影响神经前体增殖，我们在出生后进行了EDU脉冲 体内实验第7天。我们的研究结果表明，JKO小鼠在V-SVZ中的增殖性神经前体细胞较少 相对于WT小鼠。此外，JKO小鼠在以下情况下减少了MASH1+新生神经元的数量 与WT小鼠相比。总而言之，这些数据支持这样一种假设，即出生后神经发生是 部分由绝地-1依赖的小胶质细胞吞噬V-SVZ中的凋亡细胞维持。

Project Summary Jedi-1 is an engulfment receptor that mediates phagocytic clearance of apoptotic sensory neurons by satellite glia in the developing murine peripheral nervous system. The clearance of apoptotic debris is also critical for the development and maintenance of the central nervous system (CNS), in particular for postnatal neurogenesis. Neurogenesis relies on the coupling of neural stem/progenitor cell (NSPC) proliferation, newborn neuron apoptosis, and clearance of the apoptotic debris. Critically, loss of phagocytosis hinders neurogenesis. Using immunofluorescent labeling in brain sections from male and female wildtype (WT) and Jedi-1 knockout mice (JKO) in the first week of postnatal life, we show that Jedi-1 is expressed in WT microglia residing in the postnatal neurogenic niche, the ventricular-subventricular zone (V-SVZ), but absent in the knockout. Therefore, we asked whether Jedi-1 expression in microglia contributes to this coupling and thereby regulates neurogenesis. To test whether loss of Jedi-1 hinders microglial phagocytic ability, we employed an in vitro engulfment assay and found that JKO microglia display a significant reduction in engulfment relative to WT microglia. This finding was recapitulated by an accumulation of apoptotic cells in the JKO V-SVZ, as shown by TUNEL assay. To determine whether loss of Jedi-1 and subsequent disruption of microglial phagocytic ability impacts neural precursor proliferation, we performed an EdU pulse at postnatal day 7 in vivo. Our findings demonstrate that JKO mice have fewer proliferating neural progenitors in the V-SVZ relative to WT mice. Furthermore, JKO mice have reduced numbers of MASH1+ newborn neurons when compared to those of WT mice. Together, these data support the hypothesis that postnatal neurogenesis is maintained in part by Jedi-1-dependent microglial phagocytosis of apoptotic cells in the V-SVZ.