The JAK and STAT family members of the mandarin fish Siniperca chuatsi: molecular cloning, tissues distribution and immunobiological activity.

The JAK/STAT signal transduction pathway plays a critical role in host defence against viral and bacterial infections. In the present study, we report cDNA cloning and characterization of the JAK family (mJAK1-3 and mTYK2) and STAT family members (mSTAT1, mSTAT3-6) from the mandarin fish Siniperca chuatsi. To our knowledge, JAK2, TYK2 and STAT6 genes were cloned from fish for the first time. The mJAK family proteins consist of 1112-1177 residues with a FERM domain, an SH2 domain, a pseudokinase domain, and a tyrosine kinase domain. The mSTAT family members contain 716-786 residues with similar architecture, including an N-terminal domain, a coiled coil domain, a DNA binding domain, a linker domain, an SH2 domain, and a transcription activation domain. Multiple sequence alignments of mJAKs/mSTATs and phylogenetic analysis showed that mJAK1 was closed to mTYK2, and mJAK2 was closed to mJAK3. Quantitative real-time PCR results revealed that mJAK/mSTAT family members were expressed in most tissues examined except muscle. In mandarin fish fry cells, the expressions of IRF-1, Mx, SOCS1 and SOCS3 genes were significantly induced by poly(I:C) stimulation, indicating that the mJAK/mSTAT signal pathway is activated by poly(I:C). Furthermore, expressions of all four mJAKs and four mSTATs were all up-regulated after poly(I:C) stimulation, but expression of mSTAT5 was inhibited by poly(I:C). These results suggest that mandarin fish has the JAK/STAT signal transduction pathways similar to those in mammals, and these signalling pathways may play an important role in regulation of antiviral responses in fish.