FIG. 5.

VP16-CREB stimulates and KCREB inhibits adipogenesis in 3T3-L1 cells as determined by triacylglycerol storage. 3T3-L1 preadipocyte cell lines inducibly expressing VP16-CREB (clones 2-4 and 9-7) or KCREB (clones 2-1 and 2-10) or control cells (stably transfected with the plasmids, pVgRXR and pIND-LacZ) were grown to confluence as described in Materials and Methods. The cells were treated with the reagents indicated above each column of photographs. Cells treated with differentiation mixture received 10 μg of insulin per ml, 1 μM dexamethasone, and 0.3 mM Bt₂cAMP for 48 h and then were refed every 2 days with conventional medium containing 10 μg of insulin per ml. Muristerone was added to medium at a final concentration of 10 μM for the entire 10-day differentiation period. After 10 days in culture, the cells were stained with Oil Red O to visualize triacylglycerol vesicles and then counterstained with hematoxylin. The photographs show cells on day 10 of each treatment.