Hemin enhances the differentiation of mouse 3T3 cells to adipocytes

Hemin enhances the adipose differentiation of mouse 3T3-F442A cells in a medium containing high levels of adipogenic factor that is present in fetal calf serum or calf serum. This enhancement is more prominent in the presence of insulin. Hemin also promotes adipose differentiation in a medium containing 10% cat serum, which has very little adipogenic factor; this effect is in contrast to that of insulin, which is relatively ineffective in promoting adipose differentiation in this medium. Adipose differentiation of 3T3-F442A cells is inhibited by the addition of aminotriazole, an inhibitor of heme biosynthesis. The inhibition of adipose differentiation by aminotriazole is prevented by the simultaneous addition of hemin and aminotriazole. These results indicate that treatment with hemin can promote the differentiation of fibroblasts to adipocytes in vitro, and they raise the possibility that endogenous heme may have a physiological role in the differentiation of fibroblasts to adipocytes in vivo.