Salinity and bisphenol A alter cellular homeostasis and immune defense by heat shock proteins in the intertidal crab Macrophthalmus japonicus

Abstract

Heat shock proteins (HSPs) play crucial roles in cellular metabolic processes, as well as in protective immune responses. In this study, we determined the cellular and immune-related functions of HSPs in the intertidal mud crab Macrophthalmus japonicus under osmotic and bisphenol A (BPA) exposure stress. We performed transcriptional profiling of six HSP genes (HSP70, HSP60, HSP90, HSP83, HSP40, and HSP21) in M. japonicus gills and hepatopancreas. Tissue-specific responses were observed as differentially expressed HSP transcripts in M. japonicus. Under osmotic stress, expression levels of HSP70, HSP90 and HSP40 mRNA increased at high salinity (40 psμ), and decreased at low salinity (10 psμ) in M. japonicus gills. In contrast, HSP60 expression was significantly diminished under high salinity, and increased under low salinity. HSP21 was down-regulated under all salinity changes over 1, 4, and 7 days. In the hepatopancreas, under osmotic stress, most HSP transcripts were up-regulated at an early exposure time point (day 1) with subsequent down-regulation (day 7). On day 4, HSP70, HSP60, HSP90 and HSP40 transcript levels increased in M. japonicus, whereas HSP83 and HSP21 transcript levels decreased in the hepatopancreas following most salinity changes. In addition, BPA exposure generally induced HSP responses in the gills. In particular, HSP70 and HSP83 were significantly up-regulated at all concentrations of BPA on days 1 and 4. However, induced responses of HSP transcripts diminished by day 7, except for HSP83 and HSP40. In the hepatopancreas, HSP70 and HSP90 mRNA expression showed significant up-regulation, whereas transcription of HSP60, HSP83, and HSP21 was down-regulated on days 1 and 4. These results suggested that HSPs are differently involved in the molecular adaptation and defense responses of crabs to BPA and osmotic stress.