OPTN translocates to an ATG9A-positive compartment to regulate innate immune signalling and cytokine secretion

Abstract

Optineurin (OPTN) is a multifunctional protein involved in autophagy, secretion as well as NF-{kappa}B and IRF3 signalling and mutations are associated with several human diseases including primary open-angle glaucoma (POAG), amyotrophic lateral sclerosis (ALS), Pagets disease of bone (PDB) and Crohns disease (CD). Here we show that, in response to viral RNA, OPTN translocates to foci in the perinuclear region, where it negatively regulates NF-{kappa}B and IRF3 signalling pathways and downstream pro-inflammatory cytokine secretion. These OPTN foci consist of a tight cluster of small membrane vesicles, which are positive for marker proteins of the trans-Golgi network/recycling compartment - most notably ATG9A. Disease mutations linked to POAG cause aberrant formation of this compartment in the absence of stimuli, which correlates with the ability of OPTN to inhibit signalling. Using proximity labelling proteomics (BioID), we identify the linear ubiquitin assembly complex (LUBAC), CYLD and TBK1 as part of the OPTN interactome and show that these proteins, along with NEMO, are recruited to this OPTN-positive perinuclear compartment. Together, we propose OPTN might be responsible for dampening the NF-{kappa}B and IRF3 signalling responses through the sequestration of LUBAC and other positive regulators of these pathways in this dsRNA-induced compartment leading to altered pro-inflammatory cytokine secretion.\n\nSummaryDisease associated OPTN mutations impact on the formation of the perinuclear compartment and result in hypo- or hyper-activation of the immune response, which could drive the development of human diseases such as POAG, ALS and also Pagets disease of bone.