The two TRIM25 isoforms were differentially induced in Larimichthys crocea post poly (I:C) stimulation.

In this study, we identified and characterized a tripartite motif containing 25 (TRIM25) gene homologue, LcTRIM25, from large yellow croaker (Larimichthys crocea). Two isoforms of LcTRIM25, which were generated via alternative splicing, were identified via a molecular analysis of cDNA clones. The long isoform of LcTRIM25 (termed as LcTRIM25-L) contained the full open reading frame of the gene, encoded a protein of 698 amino acid residues, and possessed 11 exons. The short isoform of LcTRIM25 (termed as LcTRIM25-S) contained 9 exons and encoded a protein of 665 amino acid residues. The two LcTRIM25 isoforms contained a conserved Really Interesting New Gene (RING) domain, a B-box2 domain, a Coiled-coil domain (CCD), and variable C-terminal PRY/SPRY domains. Phylogenetic analysis showed that the two LcTRIM25 isoforms of the large yellow croaker was clustered together with their counterparts from other teleost fish. The Real-time PCR analysis showed that the LcTRIM25-L and LcTRIM25-S isoforms were both ubiquitously expressed in nine examined tissues in the large yellow croaker, with predominant expressions in the liver. The expression levels of the two isoforms of LcTRIM25 were rapidly and significantly upregulated in vivo after poly (I:C) stimulation in peripheral blood, head kidney, spleen and liver. Moreover, LcTRIM25-L and LcTRIM25-S showed differential expression post poly(I:C) stimulation. LcTRIM25 may have a dual role in innate immunity via alternative gene splicing. These results indicated that LcTRIM25 is likely to be involved in antiviral immune responses.