Molecular characterization and functional analysis of duck IKKα

I kappa B kinase alpha (IKK alpha) is a vital component of the IKK complex, which is involved in innate immune response, inflammation, cell death and proliferation. Although the functional characteristics of IKK alpha have been extensively studied in mammals and fish, the roles of IKK alpha in avian remain largely unknown. In this study, we cloned and characterized the duck IKK alpha (duIKK alpha) gene for the first time. DuIKK alpha encoded a protein of 757 amino acid residues and showed high sequence identities with the goose IKK alpha. The duIKK alpha was expressed in all tested tissues, and a relatively high expression of duIKK alpha mRNA was detected in liver and heart. Overexpression of duIKK alpha dramatically increased NF-kappa B activity and induced the expression of duck cytokines IFN-beta, IL-1 beta, IL-6, IL 8 and RANTES in DEFs. Knockdown of duIKK alpha by small interfering RNA significantly decreased LPS-, poly(I:C)-, poly(dA:dT)-, duck enteritis virus (DEV)-, or duck Tembusu virus (DTMUV)-induced NF-kappa B activation. Moreover, duIKK alpha exhibited antiviral activity against DTMUV infection. These findings provide important insights into the roles of duIKK alpha in avian innate immunity.