Transcriptional regulation of heat shock protein 70 genes by class I histone deacetylases in the red flour beetle, Tribolium castaneum.

The regulatory function of histone acetylation in the expression of genes encoding heat shock proteins (Hsps) has been documented in Drosophila melanogaster; however, knowledge of the role of acetylation in modulating Hsps in other insect pests is limited. In this study, two full-length cDNAs encoding inducible Hsp70 (designated TcHsp70) and heat shock cognate 70 (TcHsc70) were isolated and characterized in the red flour beetle, Tribolium castaneum. TcHsp70 and TcHsc70 cDNAs were 2256 and 2132 bp and encoded 1941- and 1893-bp open reading frames, respectively. The deduced TcHsp70 and TcHsc70 proteins contained 646 and 630 amino acids, respectively, and contained sequences typical of the Hsp70 family, including the EEVD motif for cytoplasmic localization. Expression patterns after heat shock indicated that TcHsp70 was strongly heat-inducible, whereas the expression level of TcHsc70 remained unchanged under heat shock. RNA interference-mediated knock-down of three genes encoding class I histone deacetylases differentially influenced both basal and heat shock inducible expression of TcHsp70 and TcHsc70, suggesting the involvement of histone acetylation in epigenetic regulation of Hsp70 transcription in T. castaneum.