The TBK1-OTUB2-IRF3 signalling complex promotes neuroinflammation and neurodegeneration

The cyclic GMP-AMP synthase (cGAS)-stimulator of interferon genes (STING) pathway-mediated chronic inflammation drives neurodegeneration in natural aging and various neurodegenerative diseases, including amyotrophic lateral sclerosis (ALS). Here, we identify Otubain-2 (OTUB2) as a pivotal regulator that orchestrates the STING signalosome to amplify inflammatory responses. The function of OTUB2 in neuroinflammation and neurodegeneration was investigated through genetic deletion and pharmacological inhibition of OTUB2 in hTARDBP transgenic mice​, adeno-associated virus-mediated TDP43 overexpression mice, and aged mice. Biochemical assays were performed to dissect underlying molecular mechanisms. OTUB2 inhibited K63 ubiquitination of TANK-binding kinase 1 (TBK1), thereby suppressing TBK1 kinase activity and promoting cell death mediated by hyperactivated receptor-interacting serine/threonine-protein kinase 1 (RIPK1). Additionally, OTUB2 functioned as a scaffold facilitating assembly of the TBK1-interferon regulatory factor 3 (IRF3) signalling complex, a prerequisite for IRF3 phosphorylation, and enhanced IRF3 dimerization by reducing its K11 ubiquitination. Genetic deletion or pharmacological inhibition of OTUB2 significantly ameliorated neuroinflammation and neurodegeneration in both ALS and aged mouse models. This study establishes OTUB2 as a critical regulator of cGAS-STING signalling and a potential therapeutic target for neuroinflammation and neurodegeneration.