title: Genomic and functional uniqueness of the TNF receptor-associated factor gene family in amphioxus, the basal chordate.
abstract: The TNF-associated factor (TRAF) family, the crucial adaptor group in innate immune signaling, increased to 24 in amphioxus, the oldest lineage of the Chordata. To address how these expanded molecules evolved to adapt to the changing TRAF mediated signaling pathways, here we conducted genomic and functional comparisons of four distinct amphioxus TRAF groups with their human counterparts. We showed that lineage-specific duplication and rearrangement were responsible for the expansion of amphioxus TRAF1/2 and 3 lineages, whereas TRAF4 and 6 maintained a relatively stable genome and protein structure. Amphioxus TRAF1/2 and 3 molecules displayed various expression patterns in response to microbial infection, and some of them can attenuate the NF-kappaB activation mediated by human TRAF2 and 6. Amphioxus TRAF4 presented two unique functions: activation of the NF-kappaB pathway and involvement in somite formation. Although amphioxus TRAF6 was conserved in activating NF-kappaB pathway for antibacterial defense, the mechanism was not the same as that observed in humans. In summary, our findings reveal the evolutionary uniqueness of the TRAF family in this basal chordate, and suggest that genomic duplication and functional divergence of the TRAF family are important for the current form of the TRAF-mediated signaling pathways in humans.
authors.affiliation: State Key Laboratory of Biocontrol, National Engineering Research Center of South China Sea Marine Biotechnology, Department of Biochemistry, College of Life Sciences, Sun Yat-sen (Zhongshan) University, Guangzhou, People's Republic of China.
authors.forename: Shaochun
authors.initials: S
authors.lastname: Yuan
authors.forename: Tong
authors.initials: T
authors.lastname: Liu
authors.forename: Shengfeng
authors.initials: S
authors.lastname: Huang
authors.forename: Tao
authors.initials: T
authors.lastname: Wu
authors.forename: Ling
authors.initials: L
authors.lastname: Huang
authors.forename: Huiling
authors.initials: H
authors.lastname: Liu
authors.forename: Xin
authors.initials: X
authors.lastname: Tao
authors.forename: Manyi
authors.initials: M
authors.lastname: Yang
authors.forename: Kui
authors.initials: K
authors.lastname: Wu
authors.forename: Yanhong
authors.initials: Y
authors.lastname: Yu
authors.forename: Meiling
authors.initials: M
authors.lastname: Dong
authors.forename: Anlong
authors.initials: A
authors.lastname: Xu
mesh_terms: D000818:Animals; D002460:Cell Line; D043344:Chordata / Q000235:genetics* / Q000502:physiology*; D004331:Drosophila melanogaster / Q000737:chemistry / Q000235:genetics / Q000276:immunology; D006367:HeLa Cells; D006801:Humans; D008969:Molecular Sequence Data; D005810:Multigene Family / Q000235:genetics / Q000276:immunology*; D016328:NF-kappa B / Q000378:metabolism; D040901:Proteomics / Q000379:methods; D015398:Signal Transduction / Q000235:genetics / Q000276:immunology; D047992:TNF Receptor-Associated Factor 2 / Q000737:chemistry / Q000235:genetics / Q000502:physiology; D048008:TNF Receptor-Associated Factor 3 / Q000737:chemistry / Q000235:genetics / Q000502:physiology; D053449:TNF Receptor-Associated Factor 4 / Q000737:chemistry / Q000235:genetics / Q000502:physiology; D048029:TNF Receptor-Associated Factor 6 / Q000737:chemistry / Q000235:genetics / Q000502:physiology; D047988:Tumor Necrosis Factor Receptor-Associated Peptides and Proteins / Q000235:genetics* / Q000502:physiology*
chemical_list: D016328:NF-kappa B; D047992:TNF Receptor-Associated Factor 2; D048008:TNF Receptor-Associated Factor 3; D053449:TNF Receptor-Associated Factor 4; D048029:TNF Receptor-Associated Factor 6; D047988:Tumor Necrosis Factor Receptor-Associated Peptides and Proteins