Glucose upregulates steroyl-CoA (SCD₁) gene transcription in 3T3-L1 adipocytes

Stearoyl-CoA desaturase (SCD) is a key regulatory enzyme in the synthesis of unsaturated fatty acids which is encoded by two genes SCD₁ and SCD₂. Induction of SCD₁ expression by carbohydrates has been demonstrated in the liver, however it is unknown whether similar regulation occurs in adipose cells. To address this question we treated 3T3-L1 adipocytes with various carbohydrates to determine the time course and dose-response of SCD₁ to these nutrients. Differentiated 3T3-L1 cells were incubated overnight in glucose-free, serum-free medium then treated with the carbohydrates. We report no induction of the SCD₁ mRNA upon treatment with 25mM fructose, 2-Deoxy-Glucose or 3-O-Methylglucose for 48 hours. Adipocytes treated with 5mM or 25mM glucose exhibited a 3-fold increase in SCD₁ mRNA content compared to cells treated with no glucose or with 1mM pyruvate. This induction was maximal after 3 hours of glucose treatment. Using run on assay, we demonstrate that this upregulation of SCD₁ mRNA by glucose was due to transcriptional activation of the SCD₁ gene. Future studies will elucidate the mechanism responsible for the transcriptional regulation of SCD₁ by glucose.