Seasonal variations of p38 MAPK phosphorylation and heat shock protein expression in red blood cells of Sparus aurata.: Involvement of p38 MAPK in the induction of hsp70

摘要

For ectothermic marine animals including fish, environmental temperature has a pervasive impact and influences functions at all levels of biological organization, from the organismal to the molecular. Understanding of how “environmental signals” such as surface and water temperature are translated into signals at the scale of the organism or cell is essential for assessing the impact of climate changes on marine animals. The aim of this project was to investigate the seasonal stress response in the red blood cells of the Mediterranean fish Sparus aurata during one year acclimation period in the field (at sea surface and at depth of 10–12 m). Molecular responses were addressed through the expression of hsp70 and hsp90 and the phosphorylation of stress-activated protein kinases (p38 MAPK). The expression of hsp70 and hsp90 was induced when the fish were acclimatized to the lowest seasonal temperatures. Increased phosphorylation of p38MAPK at the same temperatures indicated the parallel activation of MAPK signaling cascades. The expression and the activation of these particular proteins can be used as indicators of a general cold stress response mechanism known as “winter syndrome”. In order to investigate the potential involvement of p38 MAPK in the induction of the hsps in these cells, red blood cells were incubated in the presence of a p38 MAPK inhibitor at different temperatures. Inhibition of p38 MAPK resulted in the downregulation of hsp70 implicating this kinase in hsp70 induction.