Calsyntenin-3 suppresses inflammation via inhibition of TLR N-glycosylation and membrane localization.

Abstract

Excessive innate immune activation drives uncontrolled inflammation and multiple inflammatory diseases. Proper N-glycosylation of membrane-associated Toll-like receptor 4 (TLR4) is essential for its trafficking to the cell membrane and subsequent innate activation, yet the mechanisms regulating this process remain poorly understood. Through a genome-wide CRISPR screening, we identify calsyntenin-3 (CLSTN3) as a potent suppressor of TLR4-triggered inflammation in macrophages. Mechanistically, CLSTN3 binds to the oligosaccharyltransferase (OST) subunit DDOST, inhibiting its interaction with the catalytic subunit STT3A and impairing OST complex assembly, which reduces N-glycosylation and membrane translocation of TLR4. Furthermore, CLSTN3 also suppresses membrane translocation and activation of other TLRs, including TLR3, TLR7 and TLR9. In addition, <i>CLSTN3</i> expression is reduced in multiple inflammatory diseases and correlates negatively with the cytokine expression in sepsis. Our findings reveal CLSTN3 as a potent suppressor of inflammation by controlling membrane-associated TLR translocation via glycosylation inhibition, presenting a target for intervening inflammatory diseases.