HEAT-SHOCK-PROTEIN-72 RESTORES CYCLIC-AMP ACCUMULATION AFTER HEAT-SHOCK IN N18TG2 CELLS

Although there are several reports on the alteration of intracellular signal transduction during heat shock in somatic cells, the long term effects of heat shock on neuronal cells remain unknown. In this report , we investigated cyclic AMP (cAMP) accumulation and the expression of heat shock proteins following heat shock in mouse neuroblastoma N18TG 2 cells. Basal cAMP accumulation, or that stimulated by serotonin (10 mu M), cholera toxin (1 mu g/ml), and forskolin (1 mu M) was suppresse d at 0, 3, and 6 h following heat shock (45 degrees C for 30 min). The cAMP levels were restored at 15 and 24 h after heat shock, correspond ing with the expression of stress-induced heat shock protein 72 (HSP72 ). Quercetin, an inhibitor of HSP expression, decreased the expression of HSP72 and inhibited the recovery of cAMP levels 24 h after heat sh ock. Quercetin also decreased the basal expression of the constitutive heat shock cognate protein 70 (HSC70) and suppressed cAMP accumulatio n in non-heat shocked cells. These results suggest that stress-induced HSP72 restores cAMP accumulation to control levels following heat sho ck and that constitutive HSC70 is related to cAMP levels in non-stress conditions. (C) 1998 Elsevier Science B.V.