The Golgi apparatus acts as a platform for TBK1 activation after viral RNA sensing

Abstract

BackgroundAfter viral infection and the stimulation of some pattern-recognition receptors, TANK-binding kinase I (TBK1) is activated by K63-linked polyubiquitination followed by trans-autophosphorylation. While the activated TBK1 induces type I interferon production by phosphorylating the transcription factor IRF3, the precise molecular mechanisms underlying TBK1 activation remain unclear.ResultsWe report here the localization of the ubiquitinated and phosphorylated active form of TBK1 to the Golgi apparatus after the stimulation of RIG-I-like receptors (RLRs) or Toll-like receptor-3 (TLR3), due to TBK1 K63-linked ubiquitination on lysine residues 30 and 401. The ubiquitin-binding protein optineurin (OPTN) recruits ubiquitinated TBK1 to the Golgi apparatus, leading to the formation of complexes in which TBK1 is activated by trans-autophosphorylation. Indeed, OPTN deficiency in various cell lines and primary cells impairs TBK1 targeting to the Golgi apparatus and its activation following RLR or TLR3 stimulation. Interestingly, the Bluetongue virus NS3 protein binds OPTN at the Golgi apparatus, neutralizing its activity and thereby decreasing TBK1 activation and downstream signaling.ConclusionsOur results highlight an unexpected role of the Golgi apparatus in innate immunity as a key subcellular gateway for TBK1 activation after RNA virus infection.Electronic supplementary materialThe online version of this article (doi:10.1186/s12915-016-0292-z) contains supplementary material, which is available to authorized users.

PARPi triggers STING-dependent immune response and enhances therapeutic efficacy of immune checkpoint blockade independent of BRCAness

“…The multiplexed immunofluorescence IHC kit was purchased from PerkinElmer. and phospho-TBK1, immunofluorescent staining was performed essentially as described previously (8). After treatment, cells were first fixed in ice-cold methanol for 10 min at -20°C, then blocked with 10% goat serum for 30 min at room Otherwise, unpaired t-tests were used to generate two-tailed P values.…”

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

“…As an important mediator of autophagy and innate immune signalling, it is tempting to speculate that OPTN might participate in an analogous process in response to exogenous dsRNA or RNA viruses. Other proteins including the NLRP3 inflammasome or OPTN binding partners TRAF3 and TBK1 have also been found to localise to similar Golgi-proximal perinuclear microsomes upon stimulation [38,51,52], suggesting that this Golgi-proximal platform might be a common mechanism to regulate signalling, cytokine secretion and autophagy induction in response to diverse PAMPs.…”

“…Given the well-established role of TBK1 and OPTN in the antiviral response [38], we next assessed the role of TBK1 in foci formation. TBK1 activity measured through the increase in phosphorylation (p-TBK1) was evident 30 mins post-TLR3 stimulation and returned to baseline levels after 8 hours ( Fig.…”

PLA1A Participates in the Antiviral Innate Immune Response by Facilitating the Recruitment of TANK-Binding Kinase 1 to Mitochondria

“…However, the interactions of MAVS with TBK1 and TBK1 with IRF3 were reduced and the amount of TBK1 that associated with mitochondria was decreased in PLA1A silenced cells; therefore, it is possible that PLA1A modulates TBK1 activation through controlling the recruitment and the local concentration of TBK1. P-TBK1 was reported to localize on the mitochondria and Golgi apparatus in response to RNA virus infections [29,30], while p-TBK1 shows a cell type-specific subcellular localization upon DNA virus infection, either on mitochondria or co-localized with STING or on other structures [27,30]. In our research, PLA1A knockdown reduced the distribution of p-TBK1 on mitochondria in SeV-infected cells as well as uninfected cells, suggesting that mitochondrial localized p-TBK1 participates in type I IFN production.…”