Enhancement of differentiation of cultured adipogenic cells (TA1) by pertussis toxin.

Differentiation of adipocytes is controlled by a variety of hormones and growth factors. To investigate the possible role of GTP-binding proteins (G proteins) in the process of adipose conversion, we studied the effect of pertussis toxin on differentiation of the fibroblast/adipocyte cell line (TA1). Pertussis toxin potentiated dexamethasone- and indomethacin-induced adipocyte differentiation in a time- and dose-dependent fashion. Addition of dibutyryl cAMP or forskolin inhibited adipose conversion, indicating that an abolishment of inhibitory control of adenylate cyclase is not responsible for the action of pertussis toxin. The B oligomer of the toxin did not mimic the effect of the holotoxin. Pertussis toxin catalyzed ADP-ribosylation of 40,000 molecular mass protein of the membrane fraction was dose-dependently inhibited by the pretreatment of the cells with the toxin. These results indicate the possible involvement of pertussis toxin-sensitive G proteins in adipogenesis.