Molecular cloning, characterization and expression patterns of HSP70 and HSP60 in the pufferfish (Takifugu rubripes)

Abstract

Takifugu rubripes is a commercially important fish in the Chinese aquaculture industry due to its excellent meat quality. In eukaryotic cells, heat shock proteins (HSPs) play a crucial role in maintaining intracellular protein homeostasis. They play significant roles in response to adverse environmental stresses in aquatic animals. In this study, we used bioinformatics to comprehensively compare two different full-length cDNA sequences at the molecular level in the HSP family of T. rubripes. We performed various physicochemical studies such as race cloning and RT-qPCR, and found that TrHSP60 (575 amino acids) has a larger polypeptide, followed by TrHSP70–13 (441 amino acids). Homology and phylogenetic studies showed that these sequences have the greatest homology to Takifugu bimaculatus. The mRNA of the two genes were constitutively expressed in all tested tissues of untreated T. rubripes, including brain, muscle, kidney, liver, spleen, gill, and intestine, with highest expression levels in the intestine. Three experimental groups were established in this study, the H1 group (20 °C), H2 group (24 °C) and H3 group (28 °C), in order to analyze the expressed levels of TrHSP70 in T. rubripes. To understand the role of HSPs in temperature stress in T. rubripes, we analyzed the expression levels of HSPs in T. rubripes at different temperatures. The results showed that the mRNA expression of the HSP gene were influenced by temperature stress. Gene expression of TrHSP70 and TrHSP60 were mainly up-regulated at 12 h and 48 h in the H1 group, respectively. Meanwhile, gene expression of TrHSP70 was highest at 48 h in the H3 group and TrHSP60 reached was lowest at 24 h in the H3 group. The results showed that the two genes were constitutively expressed genes, which play an important role in maintaining normal physiological function and stress responses. The results show that TrHSP70 and TrHSP60 are constitutively expressed genes, which plays important role in maintaining normal physiological function and coping with stress.