Shiraishi Akira, Uruno Takehito, Sanematsu Fumiyuki, Ushijima Miho, Sakata Daiji, Hara Toshiro, Fukui Yoshinori
From the Division of Immunogenetics, Department of Immunobiology and Neuroscience, Medical Institute of Bioregulation.
Department of Pediatrics, Graduate School of Medical Sciences, and.
J Biol Chem. 2017 Feb 10;292(6):2191-2202. doi: 10.1074/jbc.M116.736306. Epub 2016 Dec 27.
DOCK8 is an atypical guanine nucleotide exchange factor for Cdc42, and its mutations cause combined immunodeficiency in humans. Accumulating evidence indicates that DOCK8 regulates the migration and activation of various subsets of leukocytes, but its regulatory mechanism is poorly understood. We here report that DOCK8-deficient macrophages exhibit a migration defect in a 2D setting. Although DOCK8 deficiency in macrophages did not affect the global Cdc42 activation induced by chemokine stimulation, rescue experiments revealed that the guanine nucleotide exchange factor activity of DOCK8 was required for macrophage migration. We found that DOCK8 associated with LRAP35a, an adaptor molecule that binds to the Cdc42 effector myotonic dystrophy kinase-related Cdc42-binding kinase, and facilitated its activity to phosphorylate myosin II regulatory light chain. When this interaction was disrupted in WT macrophages, they showed a migration defect, as seen in DOCK8-deficient macrophages. These results suggest that, during macrophage migration, DOCK8 links Cdc42 activation to actomyosin dynamics through the association with LRAP35a.
DOCK8是一种针对Cdc42的非典型鸟嘌呤核苷酸交换因子，其突变会导致人类出现联合免疫缺陷。越来越多的证据表明，DOCK8调节各种白细胞亚群的迁移和激活，但其调节机制尚不清楚。我们在此报告，DOCK8缺陷型巨噬细胞在二维环境中表现出迁移缺陷。尽管巨噬细胞中DOCK8的缺失并不影响趋化因子刺激诱导的整体Cdc42激活，但拯救实验表明，DOCK8的鸟嘌呤核苷酸交换因子活性是巨噬细胞迁移所必需的。我们发现DOCK8与LRAP35a相关联，LRAP35a是一种衔接分子，可与Cdc42效应器强直性肌营养不良激酶相关的Cdc42结合激酶结合，并促进其磷酸化肌球蛋白II调节轻链的活性。当这种相互作用在野生型巨噬细胞中被破坏时，它们表现出迁移缺陷，这与DOCK8缺陷型巨噬细胞中的情况相同。这些结果表明，在巨噬细胞迁移过程中，DOCK8通过与LRAP35a的关联将Cdc42激活与肌动球蛋白动力学联系起来。
