DNA synthesis and cell division related to adipose differentiation of 3T3 cells

Adipose differentiation of 3T3-F442A cells in surface cultures depends on adipogenic factor present in the culture medium. We found that after stimulation with adipogenic serum, 3T3-F442A cell underwent a burst of DNA synthesis before adipose conversion was manifested by an augmented lipogenic enzyme activity. In differentiating cells, DNA synthesis, judged by a 100-fold higher rate of [3H]thymidine incorporation into TCA-insoluble material, was followed by a 100-fold increase in the activity of glycerophosphate acyltransferase. Cytosine arabinoside, added to the cultures at a concentration of 3 micrograms/ml, exerted 95% inhibition of [3H]thymidine incorporation and also inhibited adipose conversion. The burst of DNA synthesis correlated with a 2.5-fold increase in the amount of DNA and in the number of cells in the culture. The DNA content was the same in differentiated and nondifferentiated cells. We conclude that after the interaction with the adipogenic factor, the cells go through DNA synthesis and cell division essential for adipose conversion.