Nicotine-stimulated proteins in mouse cells are distinct from heat-shock proteins

Treatment of mouse tissue-culture cells with nicotine concentrations of 1 mM or less had no significant effects on cell viability, morphology or protein synthesis, but higher concentrations resulted in both altered cell morphology (rounding and vacuolization) and alterations in [3H]leucine-labelled protein profiles on sodium dodecyl sulphate/polyacrylamide gels. The synthesis of a Mr-70 000 protein was increased more than 2-fold relative to that of other major cellular proteins in 3T3 and L929 cells treated with 5 mM-nicotine and in B16 cells treated with 10 mM-nicotine, and this protein appeared to be a soluble cytoplasmic polypeptide. The radiolabelling of several additional polypeptides (Mr 62 000 in 3T3 cells, and Mr 45 000 and 38 000 in B16 cells) was also stimulated by nicotine. The nicotine-enhanced Mr-70 000 protein was distinct, however, from a major cell stress/heat-shock protein whose synthesis was stimulated after incubation of cells at 43.5 degrees C for 20 min.