SIRT1 Activates MAO-A in the Brain to Mediate Anxiety and Exploratory Drive

SIRT1 is a NAD +-dependent deacetylase that governs a number of genetic programs to cope with changes in the nutritional status of cells and organisms. Behavioral responses to food abundance are important for the survival of higher animals. Here we used mice with increased or decreased brain SIRT1 to show that this sirtuin regulates anxiety and exploratory drive by activating transcription of the gene encoding the monoamine oxidase A ( MAO-A) to reduce serotonin levels in the brain. Indeed, treating animals with MAO-A inhibitors or selective serotonin reuptake inhibitors (SSRIs) normalized anxiety differences between wild-type and mutant animals. SIRT1 deacetylates the brain-specific helix-loop-helix transcription factor NHLH2 on lysine 49 to increase its activation of the MAO-A promoter. Both common and rare variations in the SIRT1 gene were shown to be associated with risk of anxiety in human population samples. Together these data indicate that SIRT1 mediates levels of anxiety, and this regulation may be adaptive in a changing environment of food availability. [Display omitted] ► SIRT1 activity in the brain alters murine exploratory drive and anxiety ► SIRT1 activates MAO-A and decreases serotonin via deacetylation of NHLH2 ► Common variants of SIRT1 are associated with mood disorder prevalence in humans The deacetylase SIRT1 modulates brain serotonin levels to impact anxiety behavior in mice, and in humans, genetic variants in the SIRT1 gene are associated with the prevalence of mood disorders.