| Popis: |
Pattern recognition receptors (PRRs) recognise foreign antigen to direct innate and adaptive immune responses against invading pathogens. Polymorphisms in the PRR NOD2 represent the strongest genetic risk factor for the inflammatory bowel disease Crohn’s, and thus this bacterial sensor is the focus of particular research interest. By recapitulating the hypoxic conditions encountered at sites of inflammation, this study utilised quantitative phosphoproteomics to identify novel downstream signalling hubs of NOD2 and its synergistic partner Toll-like receptor 2 (TLR2). The deubiquitinase ataxin-3 was identified as being phosphorylated on serine 265, and this was mediated by RIPK2 and TBK1. Ataxin-3 was found to associate with the mitochondrial inner membrane protein MIC60, with ataxin- 3 depletion leading to dysregulation of mitochondrial DNA transcript expression and impaired oxidative phosphorylation, demonstrating a novel mitochondrial role. Interrogation of the ataxin-3 regulated ubiquitome in response to NOD2/TLR2 triggering revealed a broader immunometabolic function for ataxin-3, with the metabolism related proteins HIF1a, phospholipase D3 and LAMTOR1 identified as novel DUB targets. Ataxin-3 depleted cells show defects in PRR triggered autophagic flux, mitochondrial ROS generation and bacterial killing, suggesting the importance of this protein in the innate immune response. |
