Cell biological insights into human STING variants

Stimulator of interferon genes (STING) is an endoplasmic reticulum (ER)-localized transmembrane protein. STING induces the type I interferon and inflammatory responses against a variety of double-stranded DNA (dsDNA) viruses, which is critical to limiting their infection and replication. In certain settings where self-DNAs (genomic or mitochondrial DNA) emerge in the cytosol or the intracellular membrane traffic is impaired, STING becomes activated and triggers inflammation, which may contribute to the pathogenesis of various autoinflammatory and neurodegenerative diseases including COPA syndrome and Parkinson's disease. The human STING gene holds genetic heterogeneity with R232, HAQ (R71H-G230A-R293Q), and H232 being the most common variants, and population stratification. A very recent study has shown that HAQ, not R232 or H232, mediates completely clinical protection in the pathogenesis of COPA syndrome. These results reveal, for the first time, the distinct activities of the major variants in the context of pathogenesis of autoinflammatory diseases. Besides these major variants, there exist minor pathogenic STING variants that cause an autoinflammatory disease called STING-associated vasculopathy with onset in infancy (SAVI). This review summarizes recent insights into human STING variants and their inflammatory activities.Key words: innate immunity, STING variants, COPA syndrome, membrane traffic, the Golgi.