title: Involvement of fish signal transducer and activator of transcription 3 (STAT3) in SGIV replication and virus induced paraptosis.
abstract: Signal transducer and activator of transcription 3 (STAT3) is an important transcription factor which plays crucial roles in immune regulation, inflammation, cell proliferation, transformation, and other physiological processes of the organism. In this study, a novel STAT3 gene from orange spotted grouper (Ec-STAT3) was cloned and characterized. Bioinformatic analysis revealed that full-length of Ec-STAT3 was 3105-bp long and contained a 280-bp 5'UTR, a 470-bp 3'UTR, and a 2355-bp open reading frame (ORF) that encoded a 784-amino acid peptide. The deduced protein of Ec-STAT3 showed 98% identity to that of turbot (Scophthalmus maximus). Amino acid alignment showed that Ec-STAT3 contained four conserved domains, including a protein interaction domain, a coiled coil domain, a DNA binding domain, and an SH2 domain. Quantitative real-time PCR analysis showed that the highest expression level was detected in the liver, followed by skin and spleen. After injection with Singapore grouper iridovirus (SGIV), the transcript of Ec-STAT3 in spleen was increased significantly. To further explore the function of Ec-STAT3, we investigated the roles of Ec-STAT3 in SGIV infection in vitro. Immune fluorescence analysis indicated that SGIV infection altered the distribution of phosphorylated Ec-STAT3 in nucleus, and a small part of phosphorylated Ec-STAT3 was associated with virus assembly sites, suggesting that Ec-STAT3 might be important for SGIV infection. Using STAT3 specific inhibitor, S3I-201, we found that inhibition of Ec-STAT3 activation decreased the SGIV replication significantly. Moreover, inhibition of Ec-STAT3 activation obviously altered SGIV infection induced cell cycle arrest and the expression of pro-survival genes, including Bcl-2, Bcl-xL and Bax inhibitor. Together, our results firstly demonstrated the critical roles of fish STAT3 in DNA virus replication and virus induced paraptosis, but also provided new insights into the mechanism of iridovirus pathogenesis.
authors.affiliation: Key Laboratory of Tropical Marine Bio-resources and Ecology, South China Sea Institute of Oceanology, Chinese Academy of Sciences, 164 West Xingang Road, Guangzhou 510301, PR China; University of Chinese Academy of Sciences, Beijing, PR China.
authors.forename: Xiaohong
authors.initials: X
authors.lastname: Huang
authors.affiliation: Key Laboratory of Tropical Marine Bio-resources and Ecology, South China Sea Institute of Oceanology, Chinese Academy of Sciences, 164 West Xingang Road, Guangzhou 510301, PR China; University of Chinese Academy of Sciences, Beijing, PR China.
authors.forename: Youhua
authors.initials: Y
authors.lastname: Huang
authors.affiliation: Key Laboratory of Tropical Marine Bio-resources and Ecology, South China Sea Institute of Oceanology, Chinese Academy of Sciences, 164 West Xingang Road, Guangzhou 510301, PR China; University of Chinese Academy of Sciences, Beijing, PR China.
authors.forename: Ying
authors.initials: Y
authors.lastname: Yang
authors.affiliation: Key Laboratory of Tropical Marine Bio-resources and Ecology, South China Sea Institute of Oceanology, Chinese Academy of Sciences, 164 West Xingang Road, Guangzhou 510301, PR China; University of Chinese Academy of Sciences, Beijing, PR China.
authors.forename: Shina
authors.initials: S
authors.lastname: Wei
authors.affiliation: Key Laboratory of Tropical Marine Bio-resources and Ecology, South China Sea Institute of Oceanology, Chinese Academy of Sciences, 164 West Xingang Road, Guangzhou 510301, PR China; University of Chinese Academy of Sciences, Beijing, PR China. Electronic address: qinqw@scsio.ac.cn.
authors.forename: Qiwei
authors.initials: Q
authors.lastname: Qin
mesh_terms: D000595:Amino Acid Sequence; D000636:Aminosalicylic Acids; D000818:Animals; D001483:Base Sequence; D001557:Benzenesulfonates; D016923:Cell Death / Q000502:physiology*; D003001:Cloning, Molecular; D016000:Cluster Analysis; D019295:Computational Biology; D017931:DNA Primers / Q000235:genetics; D004266:DNA Virus Infections / Q000378:metabolism / Q000662:veterinary*; D005393:Fish Diseases / Q000378:metabolism / Q000821:virology*; D005453:Fluorescence; D040461:Gene Components; D007497:Iridoviridae / Q000502:physiology*; D008969:Molecular Sequence Data; D010473:Perciformes; D010766:Phosphorylation; D010802:Phylogeny; D017434:Protein Structure, Tertiary; D060888:Real-Time Polymerase Chain Reaction; D050796:STAT3 Transcription Factor / Q000378:metabolism*; D016415:Sequence Alignment; D017422:Sequence Analysis, DNA / Q000662:veterinary; D017385:Sequence Homology; D013154:Spleen / Q000378:metabolism; D014779:Virus Replication / Q000502:physiology*
chemical_list: D000636:Aminosalicylic Acids; D001557:Benzenesulfonates; D017931:DNA Primers; C520337:NSC 74859; D050796:STAT3 Transcription Factor
keywords: Grouper; Paraptosis; SGIV; STAT3; Viral replication