Molecular Cloning IRF2and Tissue Distribution Of The Three MRNA Splicing Variants In Turbot, Scophthalmus Maximus

Turbot, Scophthalmus maximus originating in Europe, since it was introduced toour country, it has become an important mariculture fish species in north of China. Inrecent years, the damage from various viral epidemics in turbot has brought directlyeconomic losses. Therefore, it has important theoretical and practical significance ofthe in-depth study of turbot interferon system. Up to date, the SmIRF2has not beencloned in turbot.In this study, three full-length IRF2cDNAs and genomic sequence are clonedand identified in turbot, Scophthalmus maximus. In this paper, We found that theturbot IRF2gene have three mRNA splicing variants，and they have the same5’UTR.Length of the three mRNA splicing variants are1807bp,1678bp and1506bp,respectively. And microsatellite sequences are found in the third mRNA splicingvariant. The gene of turbot IRF2is11891bp long, containing10exons and9introns.Because of SmIRF2have three mRNA splicing variants, it can encode the two classesof proteins. Multiple alignment of amino acid sequences with other vertebrates IRF2show that SmIRF2have a high homology with other vertebrates. Similar to other fish,SmIRF2possesses a putative DNA-binding domain, an activation domain (AD) andrepression domain(RD). Phylogenetic analysis show that SmIRF2is a member of theIRF1subfamily.Reverse transcription polymerase chain reaction(RT-PCR) was used to analyzetissue distribution of SmIRF2mRNAs in healthy turbot. RT-PCR analysis revealedthat three mRNA splicing variants of SmIRF2are expressed constitutively in limitedtissue types. The expression of the first mRNA splicing variant is weak in thesetissues. The expression of the second mRNA splicing variant is higher in the kidney,spleen, skin, muscle (immunohistochemistry and non-immunogenic tissues). The expression of the third mRNA splicing variant is higher in the digestive system, suchas, stomach and intestinal, weakly in splenic immune organ expression. Theexpression of three mRNA splicing variants of SmIRF2have lower levels in brain.Through the tissue distribution studies, we learned that the the linkage expressionpattern of IRF2and Mx gene. Our findings will help us have a better understanding ofthe IFN system in turbot.