Invited Speaker 11th International Symposium on Autophagy 2025

Role of Golgi Membrane Atg8 lipidation and Ubiquitination in STING Signaling (129771)

Richard Youle 1
  1. NIH, Bethesda, MARYLAND, United States

Innate immune dsDNA sensor cGAS and downstream cGAMP receptor STING mediate interferon and NFkB signaling. STING activation induces LC3 lipidation of Golgi membranes as well as K63- and linear/M1-chain ubiquitination of Golgi vesicles. HOIP mediated linear ubiquitin chain ubiquitination activates the NFkB arm of innate immune signaling. Atg8 lipidation is not required for Golgi localized linear chain ubiquitination but it does mediate intracellular redistribution of STING into tight perinuclear foci. Ubiquitin binding proteins, TNIP1 and autophagy receptors p62, NBR1, NDP52, TAX1BP1, and OPTN associate with STING-induced Golgi localized ubiquitin chains and LC3B-labeled vesicles. p62 and NBR1 act redundantly in spatial clustering of the LC3B-labeled vesicles in the perinuclear region. While TBK1 kinase activity is not required for the recruitment of TNIP1 and the autophagy receptors, it does play a role in sequestration of the LC3B-labeled vesicles. The ubiquitin binding domains, rather than the LC3B-interacting regions, of TNIP1 and OPTN are specifically important for their recruitment to Ubiquitin/LC3B-associated perinuclear vesicles. Functionally, we find that TNIP1 and OPTN play a role in STING-mediated innate immune signaling, with TNIP1 acting as a significant negative regulator of both NF-κB- and interferon-mediated gene expression. Together, these results highlight autophagy-independent mechanisms of autophagy receptors and TNIP1 with unanticipated roles in regulating STING-mediated innate immunity.