Induction of a novel set of polypeptides by heat shock or sodium arsenite in cultured cells of rainbow trout, Salmo gairdnerii

Abstract

The heat-shock response was characterized in cultured fibroblasts [gonadal RTG-2 cells] of the rainbow trout, Salmo gairdneri. The response was elicited by 2 different stress situations; cells were either subjected to higher temperatures than normal (27 to 29.degree. C as opposed to 22.degree. C) or were incubated in medium containing sodium arsenite (15-100 .mu.M final concentration). The response of the cells to these conditions is to synthesize a set of new polypeptides, the heat-shock polypeptides (hsps), that are not present or present in extremely low amounts in noninduced cells. Furthermore, during prolonged arsenite induction, the synthesis of normal cellular proteins is repressed. In trout fibroblasts, at least 6 hsps are detectable. These range from 30,000 to 87,000 in MW and are referred to as hsp30, hsp32, hsp42, hsp62, hsp70, and hsp87. The hsp30 and hsp70 components are the most abundant and can be visualized by Coomassie blue staining of gels after prolonged induction. The heat-shock response is a reversible process in trout cells. Results of in vitro translation of mRNA from induced cells indicate that the control of hsp induction may be at the transcriptional level. Hsp70 from trout comigrates with the major hsp from Drosophila melanogaster on sodium dodecyl sulfate-polyacrylamide gels, suggesting that this protein may be highly conserved in evolution.