Induction of apoptosis in sea bream fibroblasts by Vibrio harveyi haemolysin and evidence for an anti-apoptotic role of heat shock protein 70

• Published in: Journal of fish diseases 2012-04, Vol.35 (4), p.287-302
• Main Authors: Deane, E E, Jia, A, Qu, Z, Chen, J-X, Zhang, X-H, Woo, N Y S
• Format: Article
• Language: English
• Subjects: Animals; apoptosis; Apoptosis - drug effects; Apoptosis - physiology; Bacterial Proteins - physiology; Bacterial Proteins - toxicity; Cell Line; cell lines; fibroblasts; Fibroblasts - drug effects; Fibroblasts - physiology; Fish Proteins - antagonists & inhibitors; Fish Proteins - physiology; Hemolysin Proteins - physiology; Hemolysin Proteins - toxicity; HSP70; HSP70 Heat-Shock Proteins - antagonists & inhibitors; HSP70 Heat-Shock Proteins - physiology; Marine; Mylio macrocephalus; Quercetin - pharmacology; Recombinant Proteins - toxicity; Sea Bream - physiology; Sparus sarba; Vibrio - metabolism; Vibrio - pathogenicity; Vibrio harveyi; Vibrio harveyi haemolysin
• ISSN: 0140-7775; 1365-2761
• DOI: 10.1111/j.1365-2761.2012.01346.x

In this study, we exposed black sea bream, Mylio macrocephalus (Basilewsky), fibroblast (BSF) and silver sea bream, Sparus sarba Forsskål, fibroblast (SSF) cell lines to a recombinant Vibrio harveyi haemolysin (VHH) and investigated mechanisms involved in apoptosis. A decrease in mitochondrial membrane potential, followed by an increase in caspase 3 activity, occurred within 2–8 h of VHH exposure, in both cell lines; however, VHH did not alter cellular levels of reactive oxygen species. As heat shock protein 70 (HSP70) is known to prevent the onset of apoptosis in certain mammalian cells, we aimed to test whether such a protective effect is operative in VHH‐exposed fibroblasts. The amounts of HSP70 were elevated in SSF and BSF via an acute heat shock or an acute heat shock followed by a 6 h recovery. It was found that the VHH‐mediated reduction in mitochondrial membrane potential was suppressed in cells that had a 6 h post‐heat shock recovery, and the protective effect of heat shock‐induced HSP70 was attenuated following treatment of cells with the HSP70 inhibitor, quercetin. This study demonstrates how haemolysin causes cell death via induction of apoptosis and provides evidence as to the role of HSP70 as an anti‐apoptotic factor.