Transforming growth factor β1 gene play a novel role in innate immune response in Pelteobagrus fulvidraco

Transforming growth factor-beta 1 (TGF-β1) as a member of TGF-β superfamily plays crucial roles in regulation of immune responses. Yellow catfish, <i>Pelteobagrus fulvidraco</i>, is one of the most important freshwater aquaculture species in China, but little is known about its genes related to immune response. The present study cloned cDNA encoding TGF-β1 from <i>P. fulvidraco</i>. The results showed the full-length cDNA of TGF-β1 is 2,816 bp and encodes 461 amino acids. The homology of <i>P. fulvidraco</i> TGF-β1 depicted 83% and 81% similarity to the TGF-β1 in <i>Stegastes partitus</i> and <i>Pundamilia nyererei </i>respectively. The phylogenetic tree construction revealed that <i>P. fulvidraco</i> is closely related to <i>Astyanax mexicanus</i>. Analysis of mRNA expression of TGF-β1 in different tissues (gonads, brain, liver, kidney, spleen, intestine, blood, gills, muscle and heart) revealed that TGF-β1 is predominantly expressed in liver and brain, followed by gill and spleen. TGF-β1 gene in gill and spleen up-regulated for 48h after <i>Edwardsiella ictaluri</i> and <i>Flavobacterium columnare</i> injection, then the expression showed a significant decrease (p<0.05). These results indicated that TGF-β1 contributes to the inherent immune reaction of <i>P. fulvidraco.</i>