Coincidental loss of DOCK8 function in NLRP10-deficient and C3H/HeJ mice results in defective dendritic cell migration

Significance Understanding dendritic cell (DC) migration during an immune response is fundamental to defining the rules that govern T cell-mediated immunity. We recently described mice deficient in the pattern recognition receptor NLRP10 (NLR family, pyrin domain containing 10) with a severe DC migration defect. Using whole-exome sequencing, we discovered that this defect was due to mutation of the guanine nucleotide exchange factor Dock8 (dedicator of cytokinesis 8). DOCK8 regulates cytoskeleton dynamics in leukocytes, and loss-of-function mutations cause an immunodeficiency syndrome. Mutations in other Dock genes have been reported in mice lacking innate immune pathways, and we now report two more lines with Dock8 mutations resulting in impaired DC migration. These results clarify the role of NLRP10 in DCs and confirm the essential function of DOCK8 in the immune system. Dendritic cells (DCs) are the primary leukocytes responsible for priming T cells. To find and activate naéüïve T cells, DCs must migrate to lymph nodes, yet the cellular programs responsible for this key step remain unclear. DC migration to lymph nodes and the subsequent T-cell response are disrupted in a mouse we recently described lacking the NOD-like receptor NLRP10 (NLR family, pyrin domain containing 10); however, the mechanism by which this pattern recognition receptor governs DC migration remained unknown. Using a proteomic approach, we discovered that DCs from Nlrp10 knockout mice lack the guanine nucleotide exchange factor DOCK8 (dedicator of cytokinesis 8), which regulates cytoskeleton dynamics in multiple leukocyte populations; in humans, loss-of-function mutations in Dock8 result in severe immunodeficiency. Surprisingly, Nlrp10 knockout mice crossed to other backgrounds had normal DOCK8 expression. This suggested that the original Nlrp10 knockout strain harbored an unexpected mutation in Dock8 , which was confirmed using whole-exome sequencing. Consistent with our original report, NLRP3 inflammasome activation remained unaltered in NLRP10-deficient DCs even after restoring DOCK8 function; however, these DCs recovered the ability to migrate. Isolated loss of DOCK8 via targeted deletion confirmed its absolute requirement for DC migration. Because mutations in Dock genes have been discovered in other mouse lines, we analyzed the diversity of Dock8 across different murine strains and found that C3H/HeJ mice also harbor a Dock8 mutation that partially impairs DC migration. We c