| Litopenaeus vannamei,one of the most widely cultivated shrimp species in the world,can bring huge economic benefits every year.However,the diseases,caused by white spot syndrome virus(WSSV)have resulted in high mortality and huge economic losses,seriously affecting the health of the farming industry.Study on the immune defense and pathogenic mechanisms will deepen understanding of WSSV behaviors and provide new ideas for disease control.As a transcriptional coactivator of Hippo signaling pathway,Yorkie(Yki)plays an important role in regulating physiological processes,such as organ size,tissue differentiation and immunity.In this study,LvYki,the homologous gene of Yki in L.vannamei,was characterized,and its functional mechanism during host-virus interaction was investigated.Bioinformatics analysis revealed that LvYki has conserved TEAD binding,WW and C-C domain.LvYki is evolutionarily independent of other species,and clustered with shrimp and crab.Transcription of LvYki was detected in all six tissues,including intestine,gills,hepatopancreas,heart,muscle and hemocytes.It was the highest in muscle,followed by intestines and gills,and the lowest in hemocyte.Immunofluorescence analysis revealed LvYki was mainly located in the cytoplasm.Upon WSSV stimulation,the transcription of LvYki was significantly up-regulated in hepatopancreas,while the transcription and expression of LvYki were significantly down-regulated in gill.The results showed that LvYki was closely related to WSSV infection and had tissue specificity.In order to clarify the role of LvYki,RNAi mediated by ds RNA was performed.It was found that knock-down of LvYki significantly suppressed WSSV genes transcription and viral genome replication,which reduced the mortality post WSSV infection in shrimp.Besides,knock-down of LvYki could increase hemocyte apoptosis.And overexpression of LvYki in insect cells could significantly enhance the activity of insect cells.In addition,we also found cross-talk was existed between LvYki and Wnt signaling pathway.LvYki interacted with Lvβ-catenin,which will further expand the immune regulatory network of LvYki.In summary,this study revealed that a close association between LvYki and WSSV infection,which might play a negative regulatory role in antiviral immunity.The host could effectively resist WSSV invasion by actively reducing the level of LvYki,promoting apoptosis,and inhibiting the proliferation of virus infection.The results will enrich the knowledge of the molecular mechanism of host-virus interaction,and provide a theoretical basis for WSSV control. |
