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, Pelteobagrus fulvidraco, 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 P. fulvidraco. The results showed the full-length cDNA of TGF-β1 is 2,816 bp and encodes 461 amino acids. The homology of P. fulvidraco TGF-β1 depicted 83% and 81% similarity to the TGF-β1 in Stegastes partitus and Pundamilia nyererei respectively. The phylogenetic tree construction revealed that P. fulvidraco is closely related to Astyanax mexicanus. 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 Edwardsiella ictaluri and Flavobacterium columnare injection, then the expression showed a significant decrease (p<0.05). These results indicated that TGF-β1 contributes to the inherent immune reaction of P. fulvidraco.