cAMP modulates stress protein synthesis in human monocytes-macrophages

The synthesis of heat-shock proteins (HSPs) and other stress proteins, including heme oxygenase (HO) and ferritin, is differentially induced by heat and oxidizing agents. In order to determine what role cAMP plays in those inductions in human monocytes-macrophages (m phi), we used cAMP activators or analogues alone or in combination with various stressful conditions. A stimulation in cAMP production did not per se affect stress proteins synthesis in m phi but modulated their induction in a differential way according to the stimulus. cAMP increased the synthesis of HSPs after heat shock. During erythrophagocytosis, whereas cAMP depressed the phagocytic process and the associated generation of superoxide anions, it enhanced the synthesis of HSPs, while inhibiting that of HO and ferritin. These results indicate that cAMP has a direct enhancing effect on the expression of stress proteins controlled by a classic heat-shock promoter, while decreasing their expression when induced by oxidative stress.