Schizothorax prenanti Heat Shock Protein 27 Gene: Cloning, Expression, and Comparison with Other Heat Shock Protein Genes after Poly (I:C) Induction

Simple Summary Schizothorax prenanti is a valuable cold-water fish that is commercially farmed in southwest China. Numerous aquaculture farmers have recently adopted high-density farming to achieve greater economic benefits, but this has rendered S. prenanti more susceptible to microbial pathogens and resulted in economic losses. Hence, the immune mechanisms of S. prenanti against pathogens should be investigated. Heat shock proteins (Hsps) comprise a family of molecular chaperones that are involved in immune pathways. Here, we identified and cloned the cDNA encoding SpHsp27 gene and detected its tissue distribution and using polyinosinic-polycytidylic acid [Poly (I:C)] as a viral analog to challenge the fish. We also explored the expression of SpHsp27, SpHsp60, SpHsp70, and SpHsp90 in four immune organs from fish that were injected with Poly (I:C). We found that Poly (I:C) induced SpHsp27 expression in all of these tissues, and significantly up-regulated most SpHsps genes compared with controls that were injected with phosphate-buffered saline. However, temporal expression and tissues were organ-specific. The present findings will help to further clarify the roles of Hsp genes in the mechanisms of antiviral immunity in fish. We identified and cloned cDNA encoding the heat shock protein (Hsp) 27 gene from Schizothorax prenanti (SpHsp27), and compared its expression with that of SpHsp60, SpHsp70, and SpHsp90 in the liver, head kidney, hindgut, and spleen of S. prenanti that were injected with polyinosinic-polycytidylic acid [Poly (I:C)]. The SpHsp27 partial cDNA (sequence length, 653 bp; estimated molecular mass, 5.31 kDa; theoretical isoelectric point, 5.09) contained an open reading frame of 636 bp and a gene encoding 211 amino acids. The SpHsp27 amino acid sequence shared 61.0-92.89% identity with Hsp27 sequences from other vertebrates and SpHsp27 was expressed in seven S. prenanti tissues. Poly (I:C) significantly upregulated most SpHsps genes in the tissues at 12 or 24 h (p < 0.05) compared with control fish that were injected with phosphate-buffered saline. However, the intensity of responses of the four SpHsps was organ-specifically increased. The expression of SpHsp27 was increased 163-fold in the head kidney and 26.6-fold SpHsp27 in the liver at 24 h after Poly (I:C) injection. In contrast, SpHsp60 was increased 0.97-1.46-fold in four tissues and SpHsp90 was increased 1.21- and 1.16-fold in the liver and spleen at 12 h after Poly (I:C) injection. Our findings indicated that Poly (I:C) induced SpHsp27, SpHsp60, SpHsp70, and SpHsp90 expression and these organ-specific SpHsps are potentially involved in S. prenanti antiviral immunity or mediate pathological process.