Abstract
TRAF family member-associated NF-κB activator (TANK)-binding kinase1 (TBK1) is a serine-threonine kinase at the crossroads of multiple interferon (IFN)-inducing signaling pathways in innate immunity. The importance of TBK1 in antiviral immunity is well established in mammal models, but in chicken, the molecular characterization and potential function of TBK1 remain unclear. In the present study, the open-reading frame (ORF) of chicken TBK1 (chTBK1) was cloned and characterized. The sequencing results revealed that the chTBK1 ORF consists of 2190 base pairs (bp) encoding a deduced protein of 729 amino acid residues. Multiple sequence alignment analysis demonstrated chTBK1 similarity to other birds and mammals, which indicates that it is evolutionarily conserved. Quantitative real-time PCR (qRT-PCR) results showed that chTBK1 was ubiquitously expressed in chicken tissues and expression was especially high in immune tissues. In addition, the expression of chTBK1 was significantly up-regulated by infection with avian leukosis virus subgroup J (ALV-J) both in vivo and in chicken embryo fibroblasts (CEFs) challenged with ALV-J or stimulated with poly I:C in vitro. Consistent with the activation of chTBK1, the interferon regulatory factor 3 (IRF3) and IFNβ gene in CEFs were also up-regulated after challenge with ALV-J or polyI:C. In contrast, the expression of IRF3 and IFNβ in CEFs was significantly reduced by siRNA targeting the chTBK1 gene compared with a negative control (NC) during ALV-J infection or polyI:C transfection. In conclusion, our results demonstrated that chTBK1 may be an important immunoregulator for IRF3 and IFNβ induction in response to viral stimulation in chicken.
Highlights
TBK1, termed NF-κB activating kinase or TRAF2-associated kinase, was identified as an important adaptor molecule linking upstream receptor signals to downstream gene activation in apoptotic, inflammatory and immune responses [1,2]
Conserved domains were identified in the N-terminus of the chicken TBK1 (chTBK1) protein, including the protein kinase domain and the ubiquitin-like domain, which is identical with murine and human TBK1 [5,6]
The ATP-binding site (LGQGATANV) and Ser172 residue, which are located in the protein kinase domain, were completely conserved in all of the TBK1 kinases and is consistent with those found in other species [20]
Summary
TBK1, termed NF-κB activating kinase or TRAF2-associated kinase, was identified as an important adaptor molecule linking upstream receptor signals to downstream gene activation in apoptotic, inflammatory and immune responses [1,2]. Molecular characterization and function of chicken TBK1 gene which belongs to the inhibitor of κB kinase (IKK) family [3]. As a non-canonical IKK family member, TBK1 possesses 61% sequence identity with IKKε (another non-canonical IKK member) and shares 27% primary sequence identity with IKKα/β (the canonical IKK members) [4]. Due to the sequence similarity, TBK1 is structurally identical to the other IKKs proteins, which present a trimodular architecture with an N-terminal kinase domain, an ubiquitin-like domain (absent in IKKα) and an α-helical scaffold/dimerization domain [5]. The kinase domain of TBK1, which contains the catalytic activity, is highly conserved [6]. The scaffold/dimerization domain, which extensively interacts with the kinase domain and the ubiquitin-like domain, contributes to the dimerization and substrate recognition of TBK1 [5]
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
