Sumoylation coordinates the repression of inflammatory and anti-viral gene-expression programs during innate sensing

Sumolyation regulates wide-ranging biological processes, but its influence on innate immunity is unclear. Amigorena and colleagues show that sumoylation negatively regulates interferon-β expression and anti-viral immunity. Innate sensing of pathogens initiates inflammatory cytokine responses that need to be tightly controlled. We found here that after engagement of Toll-like receptors (TLRs) in myeloid cells, deficient sumoylation caused increased secretion of transcription factor NF-κB–dependent inflammatory cytokines and a massive type I interferon signature. In mice, diminished sumoylation conferred susceptibility to endotoxin shock and resistance to viral infection. Overproduction of several NF-κB-dependent inflammatory cytokines required expression of the type I interferon receptor, which identified type I interferon as a central sumoylation-controlled hub for inflammation. Mechanistically, the small ubiquitin-like modifier SUMO operated from a distal enhancer of the gene encoding interferon-β ( Ifnb1 ) to silence both basal and stimulus-induced activity of the Ifnb1 promoter. Therefore, sumoylation restrained inflammation by silencing Ifnb1 expression and by strictly suppressing an unanticipated priming by type I interferons of the TLR-induced production of inflammatory cytokines.