Abstract：There are few reports on the function of transforming growth factor βactivated kinase 1(TAK1) in innate immune response in fish. To explore the role of zebrafish TAK1(Danio rerio TAK1, DrTAK1) in innate immune, a new splicing isoforms of Drtak1 has been cloned and characterized in this study. The open reading frame (ORF) of the Drtak1 has 1 737 nt, which can encode 578 amino acids. DrTAK1 includes a Nterminal serine/threonine protein kinases (S/TKc) and a C-terminal coiledcoil region. The results of immunofluorescence showed that DrTAK1 is a cytoplasmic protein. Overexpression of DrTAK1 in EPC cells downregulates the activity of IFN promoter in luciferase reporter assay in EPC cells. However when cotransferred with zebrafish IRF7, the DrTAK1 can obviously promote the IFNactivation ability of IRF7. The data in this study showed that the DrTAK1 positively regulated IRF7mediated innate immune responses for the first time in zebrafish, and it laid the foundation for subsequent DrTAK1 research.
