Alteration of protein synthesis and induction of specific protein phosphorylation by hyperthermia

Confluent cultures of the mouse cell line clone 1D were subjected to 1-hr hyperthermic treatments. Temperatures were increased from the control level of 37 degrees to values ranging from 38 to 45 degrees. Protein synthesis patterns were determined in fluorograms of sodium dodecyl sulfate-polyacrylamide gels labeled with [3H]leucine. Although incorporation into most proteins was either repressed or decreased by the treatment, several proteins showed an increased label of were apparently induced de novo. Among the induced proteins was a prominent band, probably a doublet, with an estimated molecular weight of 70,000 to 69,000. Crude cell lysates made from 37 degrees, 41 degrees, and 45 degrees-treated cells were tested for kinase activity at 30 degrees by a 10-min incubation with adenosine [gamma-32P]triphosphate. Several specific proteins exhibited increased phosphorylation, while phosphorylation of other proteins decreased. The most significant increase in phosphorylation was shown by a protein with molecular weight of about 37,000. We suggest that heat treatment induces or activates one or more specific phosphokinase(s) with the ability to phosphorylate proteins with approximate molecular weights of 37,000, 36,000, 23,000, and 16,000.