# Lysine-11 ubiquitination drives type-I/III interferon induction by cGAS–STING and Toll-like receptors 3 and 4

## TL;DR

The study reveals how immune receptors activate interferon production through a new ubiquitination mechanism involving ANKIB1 and Optineurin.

## Contribution

Identifies ANKIB1-mediated lysine-11 ubiquitination as a novel mechanism for TBK1 activation in immune signaling.

## Key findings

- ANKIB1 attaches K11-linked ubiquitin chains to TLR3 and cGAS–STING signalosomes.
- Optineurin recruitment via K11 ubiquitination activates TBK1 and IRF3.
- ANKIB1 deficiency reduces IFN induction and protection against HSV-1 in mice.

## Abstract

Pattern recognition receptor (PRR)-induced interferon (IFN) is critical for effective immunity. The PRRs Toll-like receptor (TLR) 3, TLR4 and cyclic GMP–AMP synthase (cGAS), together with the stimulator of IFN genes (STING), signal through TANK-binding kinase 1 (TBK1), which activates the type-I/III IFN-inducing transcription factor interferon-response factor 3 (IRF3). The mechanism by which these PRRs activate TBK1 remains unresolved. Here we show that lysine-11 (K11)-linked ubiquitination drives TBK1 activation by these PRRs. The E3 ligase ANKIB1 attaches K11-linked ubiquitin chains to components of the TLR3- and cGAS–STING-induced signalosomes. This facilitates Optineurin recruitment to these complexes, in turn enabling recruitment and activation of TBK1 and IRF3, defining an uncharacterized signalling axis. In mice, ANKIB1 deficiency dampens IFN induction via TLR3 and cGAS–STING, reducing interferonopathy and compromising protection against HSV-1, respectively. Together, our results demonstrate an unanticipated and critical role for ANKIB1-generated K11-linked ubiquitination in the immune response activated by cGAS–STING, TLR3 and TLR4.

Betrancourt, Cinko et al. identify ANKIB1-mediated K11 ubiquitination and OPTN recruitment as a shared mechanism for driving immune signalling by cGAS, TLR3 and TLR4, with functional relevance in interferonopathy and herpes simplex virus-1 protection.