Metabolic regulation of SIRT1 transcription via a HIC1:CtBP corepressor complex.

The Sir2 histone deacetylases are important for gene regulation, metabolism, and longevity. A unique feature of these enzymes is their utilization of NAD(+) as a cosubstrate, which has led to the suggestion that Sir2 activity reflects the cellular energy state. We show that SIRT1, a mammalian Sir2 homologue, is also controlled at the transcriptional level through a mechanism that is specific for this isoform. Treatment with the glycolytic blocker 2-deoxyglucose (2-DG) decreases association of the redox sensor CtBP with HIC1, an inhibitor of SIRT1 transcription. We propose that the reduction in transcriptional repression mediated by HIC1, due to the decrease of CtBP binding, increases SIRT1 expression. This mechanism allows the specific regulation of SIRT1 in response to nutrient deprivation.