Research article

Molecular cloning and expression analysis of the STAT1 gene from olive flounder, Paralichthys olivaceus

Eun-Mi Park¹ , Jung-Ha Kang¹ , Jung Soo Seo² , GunDo Kim³ , Jongkyeong Chung⁴ and Tae-Jin Choi^1,3

¹  Biotechnology Research Institute, National Fisheries Research and Development Institute, 408-1, Sirang-Ri, Gijang-Eup, Gijang-Gun, Busan, 619-902, Republic of Korea

²  Pathology Division, National Fisheries Research and Development Institute, 408-1, Sirang-Ri, Gijang-Eup, Gijang-Gun, Busan, 619-902, Republic of Korea

³  Department of Microbiology, Pukyong National University, 599-1 Daeyeon-Dong, Nam-Gu, Busan, 608-737, Republic of Korea

⁴  Department of Biological Sciences, Korea Advanced Institute of Science and Technology, Taejon, 305-701, Republic of Korea

author email corresponding author email

BMC Immunology 2008, 9:31doi:10.1186/1471-2172-9-31

Published:	26 June 2008

Abstract

Background

Signal transducer and activator of transcription 1 (STAT1) is a critical component of interferon (IFN)-alpha/beta and IFN-gamma signaling. Although seven isoforms of STAT proteins have been reported from mammals, limited information is available for the STAT genes in fish. We isolated complementary DNA with high similarity to mammalian STAT1 from the olive flounder, Paralichthys olivaceus.

Results

A DNA fragment containing the conserved SH2 domain was amplified by RT-PCR using degenerate primers designed based on the highly conserved sequences in the SH2 domains of the zebrafish and mammalian STAT1. The complete cDNA sequence was obtained by 5' and 3' RACE. The flounder STAT1 transcript consisted of 2,909 bp that encoded a polypeptide of 749 amino acids. The overall similarity between flounder STAT1 and other STATs was very high, with the highest amino acid sequence identity to snakehead (89%). Phylogenetic analyses reveal that flounder STAT1 is in the same monophyletic group with snakehead STAT1. Quantitative real time RT-PCR and in situ hybridization revealed that STAT1 was expressed in almost all examined organs and tissues, with high expression in gill, spleen, kidney, and heart. The accumulation of STAT1 mRNA in different developmental stages, as determined by real time RT-PCR, increased with development.

Conclusion

Recent cloning of various cytokine genes and the STAT1 gene of olive flounder here suggest that fish also use the highly specialized JAK-STAT pathway for cytokine signaling. Identification of other STAT genes will elucidate in detail the signal transduction system in this fish.