Molecular cloning of heat shock protein 10 (Hsp10) and 60 (Hsp60) cDNAs and their expression analysis under thermal stress in the sea cucumber Apostichopus japonicus

Hsp10 and Hsp60 are important heat shock proteins (HSPs), which might be indispensable in the heat shock response and many other physiological processes. We obtained full-length cDNAs of genes hsp10 and hsp60 and classified their mRNA expression levels under thermal stress in the sea cucumber Apostichopus japonicus. Full-length hsp10 cDNA was 1528 bp containing a 5′ untranslated region (UTR) of 83 bp, a 3′ UTR of 1133 bp and an open reading frame (ORF) of 312 bp encoding 103 amino acid residues. Full-length hsp60 cDNA was 2560 bp containing a 118-bp 5′ UTR, a 678-bp 3′ UTR and a 1764-bp ORF encoding 586 amino acid residues. The deduced amino acid sequences of Hsp10 and Hsp60 shared the highest identity with sequences of the sea urchin Strongylocentrotus purpuratus, and phylogenetic trees showed that the evolution of Hsp10 and Hsp60 was almost in accord with the evolution of species. Further analysis by real-time PCR showed that the expression of hsp10 and hsp60 mRNA was highly up-regulated at 26 °C compared with other three groups (20, 22, 24 °C), and their expression in the intestine was in a time-dependent manner at 26 °C. The results suggested that hsp10 and hsp60 were involved in the heat-shock response in the sea cucumber A. japonicus.