Phosphorylation regulation of Lv-β-catenin of Litopenaeus vannamei by an immediate early protein WSV083 to reduce cell adhesion

Abstract

β-catenin that belongs to Armdillo family is a key molecule in the canonical Wnt signaling pathway. It participates in host immunity by activating downstream transcription factors to regulate immune-related genes. In this study, Lv-β-catenin in Pacific white shrimp Litopenaeus vannamei, which is a homologous gene of β-catenin, was investigated to explore the molecular function during white spot syndrome virus (WSSV) infection. Sequence analysis showed that Lv-β-catenin contains abundant phosphorylation sites, which indicated phosphorylation is an important pattern for β-catenin regulation. Immunoprecipitation assay showed that a WSSV immediate early protein WSV083, which was identified as a serine (Ser)/threonine (Thr) kinase, could interact with Lv-β-catenin. Further Western blot and immunofluorescence analysis suggested that WSV083 could promote degradation of Lv-β-catenin through the proteasome pathway. And the degradation of Lv-β-catenin was regulated by phosphorylation initiated at Ser56 site, which was mediated by WSV083. In addition, WSV083 could also affect phosphorylation of other Ser and Thr of Lv-β-catenin, which indicated that WSV083 could regulate Lv-β-catenin by numerous ways. Moreover, it is found that Lv-β-catenin could promote cell adhesion, while this effect could be inhibited by WSV083. In conclusion, WSSV could down regulate Lv-β-catenin and decrease cell adhesion mediated by WSV083 to resist host immunity. The study will improve understanding of the pathogenic molecular mechanism of WSSV and promote disease control.