DMH neurons regulate aging and lifespan in mice through hypothalamic-adipose inter-tissue communication.

Recent studies have shown that the hypothalamus functions as a control center of aging in mammals that counteracts age-associated physiological decline through inter-tissue communications. We have identified a key neuronal subpopulation in the dorsomedial hypothalamus (DMH), marked by Ppp1r17 expression (DMH neurons), that regulates aging and longevity in mice. DMH neurons regulate physical activity and WAT function, including the secretion of extracellular nicotinamide phosphoribosyltransferase (eNAMPT), through sympathetic nervous stimulation.

Sleep-wake patterns are altered with age, Prdm13 signaling in the DMH, and diet restriction in mice.

Old animals display significant alterations in sleep-wake patterns such as increases in sleep fragmentation and sleep propensity. Here, we demonstrated that PR-domain containing protein 13 (Prdm13)+ neurons in the dorsomedial hypothalamus (DMH) are activated during sleep deprivation (SD) in young mice but not in old mice. Chemogenetic inhibition of Prdm13+ neurons in the DMH in young mice promotes increase in sleep attempts during SD, suggesting its involvement in sleep control.

Quantification of localized NAD changes reveals unique specificity of NAD regulation in the hypothalamus.

Recently, it has become a consensus that systemic decreases in NAD are a critical trigger for age-associated functional decline in multiple tissues and organs. The hypothalamus, which contains several functionally distinct subregions called nuclei, functions as a high-order control center of aging in mammals. However, due to a technical difficulty, how NAD levels change locally in each hypothalamic nucleus during aging remains uninvestigated.

The N-Terminal Domain of SIRT1 Is a Positive Regulator of Endogenous SIRT1-Dependent Deacetylation and Transcriptional Outputs.

The NAD-dependent protein deacetylase SIRT1 regulates energy metabolism, responses to stress, and aging by deacetylating many different proteins, including histones and transcription factors. The mechanisms controlling SIRT1 enzymatic activity are complex and incompletely characterized, yet essential for understanding how to develop therapeutics that target SIRT1. Here, we demonstrate that the N-terminal domain of SIRT1 (NTERM) can trans-activate deacetylation activity by physically interacting with endogenous SIRT1 and promoting its association with the deacetylation substrate NF-κB p65.

Deficiency of Prdm13, a dorsomedial hypothalamus-enriched gene, mimics age-associated changes in sleep quality and adiposity.

The dorsomedial hypothalamus (DMH) controls a number of essential physiological responses. We have demonstrated that the DMH plays an important role in the regulation of mammalian aging and longevity. To further dissect the molecular basis of the DMH function, we conducted microarray-based gene expression profiling with total RNA from laser-microdissected hypothalamic nuclei and tried to find the genes highly and selectively expressed in the DMH.

Sirt1 extends life span and delays aging in mice through the regulation of Nk2 homeobox 1 in the DMH and LH.

The mammalian Sir2 ortholog Sirt1 plays an important role in metabolic regulation. However, the role of Sirt1 in the regulation of aging and longevity is still controversial. Here we demonstrate that brain-specific Sirt1-overexpressing (BRASTO) transgenic mice show significant life span extension in both males and females, and aged BRASTO mice exhibit phenotypes consistent with a delay in aging.

A nutrient-sensitive interaction between Sirt1 and HNF-1α regulates Crp expression.

Silent information regulator 2 (Sir2) orthologs are an evolutionarily conserved family of NAD-dependent protein deacetylases that regulate aging and longevity in model organisms. The mammalian Sir2 ortholog Sirt1 regulates metabolic and stress responses through the deacetylation of many transcriptional regulatory factors. To elucidate the mechanism by which Sirt1 controls gene expression in response to nutrient availability, we devised a bioinformatic screen combining gene expression analysis with phylogenetic footprinting to identify transcription factors as new candidate partners of Sirt1.

SIRT1 promotes the central adaptive response to diet restriction through activation of the dorsomedial and lateral nuclei of the hypothalamus.

Diet restriction retards aging and extends lifespan by triggering adaptive mechanisms that alter behavioral, physiological, and biochemical responses in mammals. Little is known about the molecular pathways evoking the corresponding central response. One factor that mediates the effects of diet restriction is the mammalian nicotinamide adenine dinucleotide (NAD)-dependent deacetylase SIRT1.

Circadian clock feedback cycle through NAMPT-mediated NAD+ biosynthesis.

The circadian clock is encoded by a transcription-translation feedback loop that synchronizes behavior and metabolism with the light-dark cycle. Here we report that both the rate-limiting enzyme in mammalian nicotinamide adenine dinucleotide (NAD+) biosynthesis, nicotinamide phosphoribosyltransferase (NAMPT), and levels of NAD+ display circadian oscillations that are regulated by the core clock machinery in mice. Inhibition of NAMPT promotes oscillation of the clock gene Per2 by releasing CLOCK:BMAL1 from suppression by SIRT1.