Toll-receptor 9 gene in the black tiger shrimp ( Penaeus monodon ) induced the activation of the TLR–NF-κB signaling pathway

摘要

Abstract Toll receptors are important pathogen recognition receptors (PRRs) in shrimps, which play a vital role in defending against virus and bacterial challenge. In this paper, the characterization and functional analysis of a Toll 9 receptor gene from Penaeus monodon was performed in HEK293T cells. Data showed that PmToll 9 can activate the NF-κB promoter activities of TLR pathway, while ISRE and IFN-β promoter cannot be activated obviously in HEK293T cells using dual-luciferase reporter system. The downstream immune factors of IL-8, IκB-α, and TRAF6 were activated by PmToll 9 and IL-8 showed the most significant up-regulation in expression levels, indicating the activities of NF-κB can be mediated by PmToll 9. Six LRRs-deletion mutants were constructed and results showed these mutants had obvious declines in luciferase activities, among which the mutant pCMV-DeLRR4 showed the most significant decline. qPCR data indicated LRRs-deletion mutants efficiently impaired the activities of the downstream immune factors IL-8, IκB-α, and TRAF6. It demonstrates that LRRs-deletion mutants could result in the weaken abilities of PmToll 9 in signaling transduction. Overexpression of Pm Toll9-GFP fusion protein in Hela cells revealed the primary cellular localization of PmToll 9 is in the cytoplasm. Highlights ? Shrimp PmToll 9 presents the evolutionarily conserved structure characteristics. ? PmToll 9 can activate the TLR–NF-κB pathway in HEK293T cells. ? LRR deletion impairs the activity of PmToll 9.