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

Abstract

Dendritic cells (DCs) are the primary leukocytes responsible for priming T cells. To find and activate naïve 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 conclude that DOCK8 is an important regulator of DC migration during an immune response and is prone to mutations that disrupt its crucial function.D endritic cells (DCs) are crucial for the initiation of an adaptive immune response. Upon acquiring antigens in the periphery, DCs undergo a maturation process that includes antigen processing, cytokine production, and up-regulation of costimulatory molecules. A mature DC must then migrate from peripheral tissues to draining lymph nodes (LNs) to fulfill its role as an antigen-presenting cell that primes naïve T cells (1). Although the signals that induce this maturation process are now well-established (1), relatively little is understood about DC migration aside from the primary chemotactic cue provided by CCR7 that guides DCs to the LN (2, 3).We recently described a genetically modified NLRP10 (NLR family, pyrin domain containing 10) knockout strain in which this migration step was disrupted while leaving the remainder of the DC maturation program, including CCR7 expression, intact (4).NLRP10 is the only NOD-like receptor (NLR) without a leucine-rich repeat domain, the putative pathogen-associated molecular pattern (PAMP)-binding domain. It has been proposed to both positively and negatively regulate other NLRs, such as NOD1 and NLRP3, respectively (5, 6). Although we found that NLRP3 inflammasome activation was unaltered in the absence of NLRP10, we discovered that Nlrp10 −/− mice could ...

DOCK8 Protein Regulates Macrophage Migration through Cdc42 Protein Activation and LRAP35a Protein Interaction

“…For example, the N-ethyl-N-nitrosoureamediated mutagenesis in mice has shown that DOCK8 plays an important role in B cell immunological synapse and long-lasting humoral immunity and also contributes to the development or survival of memory CD8 ϩ T cells (15)(16)(17). Furthermore, by generating DOCK8-deficient (Dock8 Ϫ/Ϫ ) mice, we and others have revealed that DOCK8 is required for DCs to migrate effectively within 3D, but not 2D, microenvironments (9,18). However, DOCK8 deficiency in DCs did not affect the global Cdc42 activation induced by chemokine stimulation (9).…”

“…Ϫ/Ϫ BM-derived DCs migrate normally on 2D surfaces, they fail to migrate effectively within 3D extracellular matrix scaffolds such as collagen gels (9,18). To examine the role of LRAP35a in DC migration, we also knocked down LRAP35a expression in Dock8 ϩ/Ϫ BM-derived DCs (Fig.…”

An Anti-Inflammatory Role for NLRP10 in Murine Cutaneous Leishmaniasis

“…A contrasting pro-inflammatory role for NLRP10 has also been implicated through a study of Shigella flexneri infection, in which NLRP10 contributed to inflammatory cytokine release, possibly by interacting with NOD1 and its down-stream pathway components (9). Although NLRP10 was implicated in adaptive immune responses through the regulation of dendritic cell migration, recent studies revealed a coincident mutation in DOCK8 in NLRP10-deficient mice, and suggested that DOCK8 was responsible for the observed phenotype (10). Thus, the functions of NLRP10 in innate immunity need further investigation.…”

DOCK8 regulates signal transduction events to control immunity

“…Similarly, DOCK8 regulates Cdc42 activation in dendritic cells, which is required for their accumulation in the lymph node for T-cell priming. [26][27][28] More recently, DOCK8 was also shown to regulate macrophage migration through an interaction with LRAP35, linking Cdc42 to actomyosin dynamics. 29 Thus, in this context, DOCK8 can activate Cdc42, but also function as an adaptor/ scaffold molecule to link Cdc42 to the cytoskeleton.…”