Cloning, identification and function analysis of a Chibby homolog from Litopenaeus vannamei

Chibby, a vital inhibitor molecule of Wnt/β-catenin signaling pathway, participates in development and stem cell differentiation through the regulation of β-catenin. Our previous studies have demonstrated that Litopenaeus vannamei β-catenin (Lv-β-catenin) was involved in WSSV infection and could inhibit virus replication by modulating the host immune system. In the study, a Chibby homolog from L. vannamei (designed as Lv-Chibby) was isolated and its role in WSSV infection was investigated. Sequence analysis suggested that Lv-Chibby was a novel homolog of Chibby family. It could transcript in all examined tissues, including hemocyte, gill, intestine, hepatopancreas, muscle and heart. Real-time quantitative PCR demonstrated that Lv-Chibby could take part in WSSV infection and be down-regulated by WSSV. Further studies confirmed that Lv-Chibby was able to interact with Lv-β-catenin. Moreover, the relationship of Lv-β-catenin, Lv-Chibby and WSSV069 was investigated. It was shown that Lv-Chibby enhanced the interaction between Lv-β-catenin and WSSV069. Interestingly, WSSV069 promoted the interaction between Lv-β-catenin and Lv-Chibby under high concentration, while low concentration of WSSV069 inhibited their interaction. A subsequent immunofluorescence assay revealed that WSSV069 appeared to reduce the nuclear entry of Lv-β-catenin. In sum, these results implied that Wnt/β-catenin signal pathway plays an important role in the defense against virus, and Chibby could be modulated by WSSV to regulate the signal pathway.