INAVA-ARNO complexes bridge mucosal barrier function with inflammatory signaling

Abstract

Homeostasis at mucosal surfaces requires cross-talk between the environment and barrier epithelial cells. Disruption of barrier function typifies mucosal disease. Here we elucidate a bifunctional role in coordinating this cross-talk for the inflammatory bowel disease risk-gene INAVA. Both activities require INAVA’s DUF3338 domain (renamed CUPID). CUPID stably binds the cytohesin ARF-GEF ARNO to effect lateral membrane F-actin assembly underlying cell-cell junctions and barrier function. Unexpectedly, when bound to CUPID, ARNO affects F-actin dynamics in the absence of its canonical activity as a guanine nucleotide-exchange factor. Upon exposure to IL-1β, INAVA relocates to form cytosolic puncta, where CUPID amplifies TRAF6-dependent polyubiquitination and inflammatory signaling. In this case, ARNO binding to CUPID negatively-regulates polyubiquitination and the inflammatory response. INAVA and ARNO act similarly in primary human macrophages responding to IL-1β and to NOD2 agonists. Thus, INAVA-CUPID exhibits dual functions, coordinated directly by ARNO, that bridge epithelial barrier function with extracellular signals and inflammation.

Peptidoglycan Metabolite Photoaffinity Reporters Reveal Direct Binding to Intracellular Pattern Recognition Receptors and Arf GTPases

“…Indeed, recent additional studies have shown that expression of C1orf106/INAVA modulates ARNO (GTP-Arf6 GEF) regulation of MDP-induced NOD2 activation. 51 The cellular mechanisms and structural basis by which MDP directly binds NOD2 and GTP-Arf6 is unknown and ongoing in our laboratory, which should provide important insights into innate immune activation and intestinal barrier homeostasis. As bacterial pathogens such as Salmonella enterica serovar Typhimurium 47 and enterohaemorrhagic Escherichia coli 48 inject proteins into host cells that modulate or directly bind Arf GTPases, these bacterial virulence factors may also suppress innate immune detection by interfering with MDP binding to NOD2 and GTP-Arf6, which should also be an interesting area of future investigation in pathogen immune evasion.…”

Six reference-quality genomes reveal evolution of bat adaptations

“…In addition to hearing-related genes, our genome-wide screen also revealed bat-specific selection on several immunity-related genes: the B-cell-specific chemokine CXCL13 45 , the asthma-associated NPSR1 46 and INAVA, a gene that is involved in intestinal barrier integrity and enhancing NF-κB signalling in macrophages 47 . Changes in these genes may have contributed to the unique tolerance of pathogens among bats 3 .…”

Six new reference-quality bat genomes illuminate the molecular basis and evolution of bat adaptations

“…INAVA encodes an immunity-related protein with a dual role in innate immunity. In intestinal epithelial cells, this gene is required for intestinal barrier integrity and the repair of epithelial junctions after injury 65,66 . Consistent with these functions, mutations in human INAVA are associated with inflammatory bowel disease 67 , a disorder characterized by chronic inflammation of the gastrointestinal tract and an increased susceptibility to microbial pathogens.…”

“…Consistent with these functions, mutations in human INAVA are associated with inflammatory bowel disease 67 , a disorder characterized by chronic inflammation of the gastrointestinal tract and an increased susceptibility to microbial pathogens. In macrophages, INAVA amplifies an IL-1β-induced pro-inflammatory response by enhancing NF-kB signalling 66 .…”

“…S10). These genes include IL17D and IL-1β , which are involved in immune system regulation 70 and NF-kB activation ( IL-1β ) 66,71 , and GP2 and LCN2 , which are involved in the response to pathogens 72,73 . Interestingly, selection was also inferred for PURB , a gene that plays a role in cell proliferation and regulates the oncogene MYC 74 , which was previously shown to be under divergent selection in bats 16 and which exhibits a unique anti-ageing transcriptomic profile in long lived Myotis bats 8 .…”