The Identification And Function Investigation Of TLRs-TRAF6/ECSIT Ubiquitination-DORSAL-IE1 Signaling Pathways In Shrimp-marsupenaeus Japonicus

BackgroundInnate immunity is a natural defense mechanism against outside infection of pathogenic microorganisms.Toll-like receptor,TLR,is an important pattern recognation receptor.In mammals,the various TLRs distinguished different pathogen associated molecular patterns(PAMPs),resulting in the transduction of unlike signaling pathways and the expression of various immune effect factors.So far,details of Toll signaling pathway in invertebrate is not clear comparing to that in vertebrates although it was first reported in D.melanogaster.Since the early 1990s,many country researchers carry out study on shrimps as it represents marine invertebrates,which aquaculture has developed rapidly and frequently catch diseases.Nowdays,the composition of the immune system and the function of some immune molecules in shrimps had been disclosed although they were reported separately.However,the systematic knowledge on the immune signaling pathway of shrimp remains to be clarified such as which TLR participates in the recognition of virus and how the signals are transducted etc.Scientific problems and significance of researchIn this study,multiple molecular biology methods will be used to identify the TLRs functioning in virus recognition and the important proteins that participate in the signaling transduction downstream of these TLRs.Our work will help to understand the immune signaling pathway functions in the virus related disease and providepotential methods for virus disease control in shrimp farming.ResultsA TLR-TRAF6/Ecsit ubiquitination-Dorsal-ie1 signaling pathway for virus amplification was existed in shrimp.MjTLR3 played an important role in recognition of virus infection;MjTLR3 functioned by promoting the translocation ofMjDorsal into nucleus and binding to the promoter of virus ie1 gene;MjEcsit was ubiquitinated downstream of MjTLR3,combined withMjDorsal and facilitated its translocation into nucleus and promoting the expression of viral gene;MjTRAF6 interacted with MjEcsit and ubiquitinated MjEcsit,functioned downstream of MjTLR3 and facilitated the amplificateion of virus and livability through MjEcsit-MjDorsal-ie1 signaling pathway.MjTLRl inhibited this signaling pathway through trigger the opposite signaling transduction and ultimately enhance the mortality of shrimp.While the MjTLR2 functions remains to be investigate.Innovation points1.The function differences of three shrimpMjTLRs in virus infection disease were revealed.2.The function and molecular mechanism ofMjTRAF6 and MjEcsit were investigated.Ubiquitination and association of functional moleculars MjTRAF6 and MjEcsit promoted WSSV replication downstream Mjsignaling pathways by regulating MjDorsal combinition with ie1 promoter.3.The MjTLR3-MjTRAF 6/MjEcsit ubiquitination-MjDorsal-IEl signaling pathwaywhich functioned in facilitating the virus amplification in shrimp wasdisclosed.