Chiba Terumasa, Otani Yoshinori, Yamaguchi Yoshihide, Ishibashi Tomoko, Hayashi Akiko, Tanaka Kenji F, Yamazaki Maya, Sakimura Kenji, Baba Hiroko
Department of Molecular Neurobiology, Tokyo University of Pharmacy and Life Sciences.
Proc Jpn Acad Ser B Phys Biol Sci. 2016;92(7):237-54. doi: 10.2183/pjab.92.237.
Phospholipase D4 (PLD4) is expressed in activated microglia that transiently appear in white matter during postnatal brain development. Previous knockdown experiments using cultured microglia showed PLD4 involvement in phagocytosis and proliferation. To elucidate the role of PLD4 in vivo, PLD4-deficient mice were generated and the cerebella were examined at postnatal day 5 (P5) and P7, when PLD4 expression is highest in microglia. Wild type microglia showed strong immunoreactivity for microglial marker CD68 at P5, whereas CD68 signals were weak in PLD4-deficient microglia, suggesting that loss of PLD4 affects microglial activation. At P5 and P7, immunostaining for anti-myelin basic protein (MBP) antibody indicated a mild but significant delay in myelination in PLD4-deficient cerebellum. Similar change was also observed in the corpus callosum at P7. However, this difference was not apparent at P10, suggesting that microglial PLD4-deficiency primarily influences the early myelination stage. Thus, microglia may have a transient role in myelination via a PLD4-related mechanism during development.
磷脂酶D4（PLD4）在出生后大脑发育过程中短暂出现在白质中的活化小胶质细胞中表达。先前使用培养的小胶质细胞进行的敲低实验表明PLD4参与吞噬作用和增殖。为了阐明PLD4在体内的作用，我们构建了PLD4基因敲除小鼠，并在出生后第5天（P5）和第7天（P7）检查小脑，此时小胶质细胞中PLD4的表达最高。野生型小胶质细胞在P5时对小胶质细胞标志物CD68显示出强烈的免疫反应性，而在PLD4缺陷的小胶质细胞中CD68信号较弱，这表明PLD4的缺失会影响小胶质细胞的活化。在P5和P7时，抗髓鞘碱性蛋白（MBP）抗体的免疫染色表明PLD4缺陷的小脑中髓鞘形成有轻微但显著的延迟。在P7时胼胝体中也观察到类似的变化。然而，这种差异在P10时并不明显，这表明小胶质细胞PLD4缺陷主要影响早期髓鞘形成阶段。因此，在发育过程中，小胶质细胞可能通过与PLD4相关的机制在髓鞘形成中发挥短暂作用。
