ABSTRACT
Traumatic brain injury (TBI) is the largest non-genetic, non-aging related risk factor for Alzheimer's disease (AD). We report here that TBI induces tau acetylation (ac-tau) at sites acetylated also in human AD brain. This is mediated by S-nitrosylated-GAPDH, which simultaneously inactivates Sirtuin1 deacetylase and activates p300/CBP acetyltransferase, increasing neuronal ac-tau. Subsequent tau mislocalization causes neurodegeneration and neurobehavioral impairment, and ac-tau accumulates in the blood. Blocking GAPDH S-nitrosylation, inhibiting p300/CBP, or stimulating Sirtuin1 all protect mice from neurodegeneration, neurobehavioral impairment, and blood and brain accumulation of ac-tau after TBI. Ac-tau is thus a therapeutic target and potential blood biomarker of TBI that may represent pathologic convergence between TBI and AD. Increased ac-tau in human AD brain is further augmented in AD patients with history of TBI, and patients receiving the p300/CBP inhibitors salsalate or diflunisal exhibit decreased incidence of AD and clinically diagnosed TBI.
Subject(s)
Alzheimer Disease/etiology , Alzheimer Disease/prevention & control , Brain Injuries, Traumatic/complications , Neuroprotection , tau Proteins/metabolism , Acetylation , Alzheimer Disease/metabolism , Animals , Anti-Inflammatory Agents, Non-Steroidal/therapeutic use , Biomarkers/blood , Biomarkers/metabolism , Brain Injuries, Traumatic/metabolism , Cell Line , Diflunisal/therapeutic use , Female , Glyceraldehyde-3-Phosphate Dehydrogenase (Phosphorylating) , Humans , Male , Mice , Mice, Inbred C57BL , Neurons/metabolism , Salicylates/therapeutic use , Sirtuin 1/metabolism , p300-CBP Transcription Factors/antagonists & inhibitors , p300-CBP Transcription Factors/metabolism , tau Proteins/bloodABSTRACT
Innate antiviral immunity deteriorates with aging but how this occurs is not entirely clear. Here we identified SIRT1-mediated DNA-binding domain (DBD) deacetylation as a critical step for IRF3/7 activation that is inhibited during aging. Viral-stimulated IRF3 underwent liquid-liquid phase separation (LLPS) with interferon (IFN)-stimulated response element DNA and compartmentalized IRF7 in the nucleus, thereby stimulating type I IFN (IFN-I) expression. SIRT1 deficiency resulted in IRF3/IRF7 hyperacetylation in the DBD, which inhibited LLPS and innate immunity, resulting in increased viral load and mortality in mice. By developing a genetic code expansion orthogonal system, we demonstrated the presence of an acetyl moiety at specific IRF3/IRF7 DBD site/s abolish IRF3/IRF7 LLPS and IFN-I induction. SIRT1 agonists rescued SIRT1 activity in aged mice, restored IFN signaling and thus antagonized viral replication. These findings not only identify a mechanism by which SIRT1 regulates IFN production by affecting IRF3/IRF7 LLPS, but also provide information on the drivers of innate immunosenescence.
Subject(s)
Antiviral Agents , Sirtuin 1 , Animals , Immunity, Innate , Interferon Regulatory Factor-3/metabolism , Interferon Regulatory Factor-7/genetics , Interferon Regulatory Factor-7/metabolism , Mice , Signal Transduction , Sirtuin 1/genetics , Sirtuin 1/metabolism , Virus ReplicationABSTRACT
Continuous supply of immune cells throughout life relies on the delicate balance in the hematopoietic stem cell (HSC) pool between long-term maintenance and meeting the demands of both normal blood production and unexpected stress conditions. Here we identified distinct subsets of human long-term (LT)-HSCs that responded differently to regeneration-mediated stress: an immune checkpoint ligand CD112lo subset that exhibited a transient engraftment restraint (termed latency) before contributing to hematopoietic reconstitution and a primed CD112hi subset that responded rapidly. This functional heterogeneity and CD112 expression are regulated by INKA1 through direct interaction with PAK4 and SIRT1, inducing epigenetic changes and defining an alternative state of LT-HSC quiescence that serves to preserve self-renewal and regenerative capacity upon regeneration-mediated stress. Collectively, our data uncovered the molecular intricacies underlying HSC heterogeneity and self-renewal regulation and point to latency as an orchestrated physiological response that balances blood cell demands with preserving a stem cell reservoir.
Subject(s)
Cell Self Renewal/immunology , Hematopoietic Stem Cells/physiology , Immune Reconstitution , Multipotent Stem Cells/physiology , Stress, Physiological/immunology , Adult , Animals , Cell Self Renewal/genetics , Cells, Cultured , Epigenesis, Genetic/immunology , Female , Fetal Blood/cytology , Flow Cytometry , Gene Knockdown Techniques , Hematopoiesis , Hematopoietic Stem Cell Transplantation/adverse effects , Humans , Immunomagnetic Separation , Infant, Newborn , Intracellular Signaling Peptides and Proteins/genetics , Intracellular Signaling Peptides and Proteins/metabolism , Male , Mice , Middle Aged , Nectins/metabolism , Primary Cell Culture , RNA-Seq , Single-Cell Analysis , Sirtuin 1/metabolism , Stress, Physiological/genetics , Transplantation, Heterologous , p21-Activated Kinases/genetics , p21-Activated Kinases/metabolismABSTRACT
A decline in capillary density and blood flow with age is a major cause of mortality and morbidity. Understanding why this occurs is key to future gains in human health. NAD precursors reverse aspects of aging, in part, by activating sirtuin deacylases (SIRT1-SIRT7) that mediate the benefits of exercise and dietary restriction (DR). We show that SIRT1 in endothelial cells is a key mediator of pro-angiogenic signals secreted from myocytes. Treatment of mice with the NAD+ booster nicotinamide mononucleotide (NMN) improves blood flow and increases endurance in elderly mice by promoting SIRT1-dependent increases in capillary density, an effect augmented by exercise or increasing the levels of hydrogen sulfide (H2S), a DR mimetic and regulator of endothelial NAD+ levels. These findings have implications for improving blood flow to organs and tissues, increasing human performance, and reestablishing a virtuous cycle of mobility in the elderly.
Subject(s)
Aging , Hydrogen Sulfide/metabolism , NAD/metabolism , Animals , Endothelial Cells/cytology , Endothelial Cells/metabolism , Humans , Mice , Mice, Knockout , Microvessels/metabolism , Mitochondria/metabolism , Muscle, Skeletal/metabolism , Neovascularization, Physiologic , Peroxisome Proliferator-Activated Receptor Gamma Coactivator 1-alpha/metabolism , Physical Conditioning, Animal , RNA Interference , RNA, Small Interfering/metabolism , Receptors, Notch/metabolism , Signal Transduction , Sirtuin 1/antagonists & inhibitors , Sirtuin 1/genetics , Sirtuin 1/metabolism , Vascular Endothelial Growth Factor A/metabolismABSTRACT
H2S is an endogenous gasotransmitter that plays an important role in physiological conditions. In this issue, Das et al. provide evidence that SIRT1-dependent angiogenesis is augmented by H2S-findings reinforced by Longchamp et al., who demonstrate that H2S-dependent angiogenesis is triggered by amino acid deprivation.
Subject(s)
NAD , Sirtuin 1ABSTRACT
The process of aging and circadian rhythms are intimately intertwined, but how peripheral clocks involved in metabolic homeostasis contribute to aging remains unknown. Importantly, caloric restriction (CR) extends lifespan in several organisms and rewires circadian metabolism. Using young versus old mice, fed ad libitum or under CR, we reveal reprogramming of the circadian transcriptome in the liver. These age-dependent changes occur in a highly tissue-specific manner, as demonstrated by comparing circadian gene expression in the liver versus epidermal and skeletal muscle stem cells. Moreover, de novo oscillating genes under CR show an enrichment in SIRT1 targets in the liver. This is accompanied by distinct circadian hepatic signatures in NAD+-related metabolites and cyclic global protein acetylation. Strikingly, this oscillation in acetylation is absent in old mice while CR robustly rescues global protein acetylation. Our findings indicate that the clock operates at the crossroad between protein acetylation, liver metabolism, and aging.
Subject(s)
Aging/metabolism , Circadian Rhythm , Liver/metabolism , Metabolic Networks and Pathways , Acetyl Coenzyme A/metabolism , Acetylation , Aging/pathology , Animals , Caloric Restriction , Histones/metabolism , Liver/pathology , Mice , NAD/metabolism , Proteins/metabolism , Sirtuin 1/metabolism , Stem Cells/metabolism , TranscriptomeABSTRACT
Longevity-promoting caloric restriction is thought to trigger downregulation of mammalian target of rapamycin complex 1 (mTORC1) signaling and upregulation of SIRT1 activity with associated health benefits. Here, we show that mTORC1 signaling in intestinal stem cells (ISCs) is instead upregulated during calorie restriction (CR). SIRT1 deacetylates S6K1, thereby enhancing its phosphorylation by mTORC1, which leads to an increase in protein synthesis and an increase in ISC number. Paneth cells in the ISC niche secrete cyclic ADP ribose that triggers SIRT1 activity and mTORC1 signaling in neighboring ISCs. Notably, the mTOR inhibitor rapamycin, previously reported to mimic effects of CR, abolishes this expansion of ISCs. We suggest that Paneth cell signaling overrides any direct nutrient sensing in ISCs to sculpt the observed response to CR. Moreover, drugs that modulate pathways important in CR may exert opposing effects on different cell types.
Subject(s)
Adult Stem Cells/metabolism , Caloric Restriction , Multiprotein Complexes/metabolism , Signal Transduction , Sirtuin 1/metabolism , TOR Serine-Threonine Kinases/metabolism , Animals , Cell Proliferation , Cyclic ADP-Ribose/metabolism , Diet , Intestinal Mucosa/metabolism , Intestines/cytology , Mechanistic Target of Rapamycin Complex 1 , Mice , Mice, Inbred C57BL , NAD/metabolism , Organoids/metabolism , Phosphorylation , Ribosomal Protein S6 Kinases, 90-kDa/metabolism , Sirtuin 2/metabolismABSTRACT
Genomic instability arising from defective responses to DNA damage1 or mitotic chromosomal imbalances2 can lead to the sequestration of DNA in aberrant extranuclear structures called micronuclei (MN). Although MN are a hallmark of ageing and diseases associated with genomic instability, the catalogue of genetic players that regulate the generation of MN remains to be determined. Here we analyse 997 mouse mutant lines, revealing 145 genes whose loss significantly increases (n = 71) or decreases (n = 74) MN formation, including many genes whose orthologues are linked to human disease. We found that mice null for Dscc1, which showed the most significant increase in MN, also displayed a range of phenotypes characteristic of patients with cohesinopathy disorders. After validating the DSCC1-associated MN instability phenotype in human cells, we used genome-wide CRISPR-Cas9 screening to define synthetic lethal and synthetic rescue interactors. We found that the loss of SIRT1 can rescue phenotypes associated with DSCC1 loss in a manner paralleling restoration of protein acetylation of SMC3. Our study reveals factors involved in maintaining genomic stability and shows how this information can be used to identify mechanisms that are relevant to human disease biology1.
Subject(s)
Genomic Instability , Micronuclei, Chromosome-Defective , Animals , Humans , Mice , Chromosomes/genetics , DNA Damage , Genomic Instability/genetics , Phenotype , Sirtuin 1 , Synthetic Lethal MutationsABSTRACT
Circadian rhythms are intimately linked to cellular metabolism. Specifically, the NAD(+)-dependent deacetylase SIRT1, the founding member of the sirtuin family, contributes to clock function. Whereas SIRT1 exhibits diversity in deacetylation targets and subcellular localization, SIRT6 is the only constitutively chromatin-associated sirtuin and is prominently present at transcriptionally active genomic loci. Comparison of the hepatic circadian transcriptomes reveals that SIRT6 and SIRT1 separately control transcriptional specificity and therefore define distinctly partitioned classes of circadian genes. SIRT6 interacts with CLOCK:BMAL1 and, differently from SIRT1, governs their chromatin recruitment to circadian gene promoters. Moreover, SIRT6 controls circadian chromatin recruitment of SREBP-1, resulting in the cyclic regulation of genes implicated in fatty acid and cholesterol metabolism. This mechanism parallels a phenotypic disruption in fatty acid metabolism in SIRT6 null mice as revealed by circadian metabolome analyses. Thus, genomic partitioning by two independent sirtuins contributes to differential control of circadian metabolism.
Subject(s)
Liver/metabolism , Sirtuins/metabolism , ARNTL Transcription Factors/metabolism , Animals , CLOCK Proteins/metabolism , Chromatin , Circadian Rhythm , Gene Expression Profiling , Mice , Mice, Knockout , Sirtuin 1/genetics , Sirtuin 1/metabolism , Sirtuins/genetics , Transcription, GeneticABSTRACT
Mitochondrial dysfunction is a common feature in neurodegeneration and aging. We identify mitochondrial dysfunction in xeroderma pigmentosum group A (XPA), a nucleotide excision DNA repair disorder with severe neurodegeneration, in silico and in vivo. XPA-deficient cells show defective mitophagy with excessive cleavage of PINK1 and increased mitochondrial membrane potential. The mitochondrial abnormalities appear to be caused by decreased activation of the NAD(+)-SIRT1-PGC-1α axis triggered by hyperactivation of the DNA damage sensor PARP-1. This phenotype is rescued by PARP-1 inhibition or by supplementation with NAD(+) precursors that also rescue the lifespan defect in xpa-1 nematodes. Importantly, this pathogenesis appears common to ataxia-telangiectasia and Cockayne syndrome, two other DNA repair disorders with neurodegeneration, but absent in XPC, a DNA repair disorder without neurodegeneration. Our findings reveal a nuclear-mitochondrial crosstalk that is critical for the maintenance of mitochondrial health.
Subject(s)
Mitophagy , Poly(ADP-ribose) Polymerases/metabolism , Sirtuin 1/metabolism , Xeroderma Pigmentosum Group A Protein/metabolism , Xeroderma Pigmentosum/physiopathology , Aging , Animals , Apoptosis , Autophagy , Caenorhabditis elegans , Cell Line , Humans , Ion Channels/metabolism , Mice , Mitochondrial Proteins/metabolism , Protein Kinases/metabolism , Rats , Uncoupling Protein 2 , Xeroderma Pigmentosum/metabolismABSTRACT
Age-related decline in mammalian circadian rhythm has been recognized for decades, but the underlying molecular mechanisms have remained elusive. In this issue of Cell, Chang and Guarente use brain-specific SIRT1 knockout mice and transgenic mice overexpressing SIRT1 to develop an enticing model for how SIRT1 helps maintain the robustness of the aging circadian clock.
Subject(s)
Aging , Circadian Clocks , Sirtuin 1/metabolism , Suprachiasmatic Nucleus/metabolism , Animals , MaleABSTRACT
SIRT1 is a NAD(+)-dependent protein deacetylase that governs many physiological pathways, including circadian rhythm in peripheral tissues. Here, we show that SIRT1 in the brain governs central circadian control by activating the transcription of the two major circadian regulators, BMAL1 and CLOCK. This activation comprises an amplifying circadian loop involving SIRT1, PGC-1α, and Nampt. In aged wild-type mice, SIRT1 levels in the suprachiasmatic nucleus are decreased, as are those of BMAL1 and PER2, giving rise to a longer intrinsic period, a more disrupted activity pattern, and an inability to adapt to changes in the light entrainment schedule. Young mice lacking brain SIRT1 phenocopy these aging-dependent circadian changes, whereas mice that overexpress SIRT1 in the brain are protected from the effects of aging. Our findings indicate that SIRT1 activates the central pacemaker to maintain robust circadian control in young animals, and a decay in this activity may play an important role in aging.
Subject(s)
Aging , Circadian Clocks , Sirtuin 1/metabolism , Suprachiasmatic Nucleus/metabolism , ARNTL Transcription Factors/genetics , Animals , Brain/metabolism , Male , Mice , Mice, Inbred C57BL , Mice, Transgenic , Neurons/metabolism , Peroxisome Proliferator-Activated Receptor Gamma Coactivator 1-alpha , Promoter Regions, Genetic , Sirtuin 1/genetics , Trans-Activators/metabolism , Transcription FactorsABSTRACT
NAD(+) is an important cofactor regulating metabolic homeostasis and a rate-limiting substrate for sirtuin deacylases. We show that NAD(+) levels are reduced in aged mice and Caenorhabditis elegans and that decreasing NAD(+) levels results in a further reduction in worm lifespan. Conversely, genetic or pharmacological restoration of NAD(+) prevents age-associated metabolic decline and promotes longevity in worms. These effects are dependent upon the protein deacetylase sir-2.1 and involve the induction of mitonuclear protein imbalance as well as activation of stress signaling via the mitochondrial unfolded protein response (UPR(mt)) and the nuclear translocation and activation of FOXO transcription factor DAF-16. Our data suggest that augmenting mitochondrial stress signaling through the modulation of NAD(+) levels may be a target to improve mitochondrial function and prevent or treat age-associated decline.
Subject(s)
Forkhead Transcription Factors/metabolism , Longevity , Mitochondria/metabolism , NAD/metabolism , Signal Transduction , Unfolded Protein Response , Aging , Animals , Caenorhabditis elegans/physiology , Caenorhabditis elegans Proteins/genetics , Caenorhabditis elegans Proteins/metabolism , Hepatocytes/metabolism , Mice , Poly(ADP-ribose) Polymerase Inhibitors , Reactive Oxygen Species/metabolism , Sirtuin 1/genetics , Sirtuin 1/metabolism , Sirtuins/genetics , Sirtuins/metabolism , Transcription Factors/metabolismABSTRACT
Ever since eukaryotes subsumed the bacterial ancestor of mitochondria, the nuclear and mitochondrial genomes have had to closely coordinate their activities, as each encode different subunits of the oxidative phosphorylation (OXPHOS) system. Mitochondrial dysfunction is a hallmark of aging, but its causes are debated. We show that, during aging, there is a specific loss of mitochondrial, but not nuclear, encoded OXPHOS subunits. We trace the cause to an alternate PGC-1α/ß-independent pathway of nuclear-mitochondrial communication that is induced by a decline in nuclear NAD(+) and the accumulation of HIF-1α under normoxic conditions, with parallels to Warburg reprogramming. Deleting SIRT1 accelerates this process, whereas raising NAD(+) levels in old mice restores mitochondrial function to that of a young mouse in a SIRT1-dependent manner. Thus, a pseudohypoxic state that disrupts PGC-1α/ß-independent nuclear-mitochondrial communication contributes to the decline in mitochondrial function with age, a process that is apparently reversible.
Subject(s)
Aging/pathology , Cell Nucleus/metabolism , Mitochondria/metabolism , NAD/metabolism , Oxidative Phosphorylation , AMP-Activated Protein Kinases/metabolism , Animals , Hypoxia-Inducible Factor 1, alpha Subunit/metabolism , Mice , Muscle, Skeletal/metabolism , Peroxisome Proliferator-Activated Receptor Gamma Coactivator 1-alpha , Reactive Oxygen Species/metabolism , Sirtuin 1/metabolism , Transcription Factors/metabolismABSTRACT
Disrupted sleep-wake and molecular circadian rhythms are a feature of aging associated with metabolic disease and reduced levels of NAD+, yet whether changes in nucleotide metabolism control circadian behavioral and genomic rhythms remains unknown. Here, we reveal that supplementation with the NAD+ precursor nicotinamide riboside (NR) markedly reprograms metabolic and stress-response pathways that decline with aging through inhibition of the clock repressor PER2. NR enhances BMAL1 chromatin binding genome-wide through PER2K680 deacetylation, which in turn primes PER2 phosphorylation within a domain that controls nuclear transport and stability and that is mutated in human advanced sleep phase syndrome. In old mice, dampened BMAL1 chromatin binding, transcriptional oscillations, mitochondrial respiration rhythms, and late evening activity are restored by NAD+ repletion to youthful levels with NR. These results reveal effects of NAD+ on metabolism and the circadian system with aging through the spatiotemporal control of the molecular clock.
Subject(s)
Circadian Clocks/physiology , Circadian Rhythm/genetics , Period Circadian Proteins/metabolism , ARNTL Transcription Factors/genetics , Age Factors , Aging/genetics , Animals , CLOCK Proteins/genetics , Circadian Rhythm/physiology , Cytokines/metabolism , Female , HEK293 Cells , Humans , Male , Mice , Mice, Inbred C57BL , NAD/metabolism , Period Circadian Proteins/genetics , Sirtuin 1/metabolism , Sirtuins/metabolismABSTRACT
Lipid droplets (LDs) provide a reservoir for triacylglycerol storage and are a central hub for fatty acid trafficking and signaling in cells. Lipolysis promotes mitochondrial biogenesis and oxidative metabolism via a SIRT1/PGC-1α/PPARα-dependent pathway through an unknown mechanism. Herein, we identify that monounsaturated fatty acids (MUFAs) allosterically activate SIRT1 toward select peptide-substrates such as PGC-1α. MUFAs enhance PGC-1α/PPARα signaling and promote oxidative metabolism in cells and animal models in a SIRT1-dependent manner. Moreover, we characterize the LD protein perilipin 5 (PLIN5), which is known to enhance mitochondrial biogenesis and function, to be a fatty-acid-binding protein that preferentially binds LD-derived monounsaturated fatty acids and traffics them to the nucleus following cAMP/PKA-mediated lipolytic stimulation. Thus, these studies identify the first-known endogenous allosteric modulators of SIRT1 and characterize a LD-nuclear signaling axis that underlies the known metabolic benefits of MUFAs and PLIN5.
Subject(s)
Fatty Acids, Monounsaturated/metabolism , Lipid Droplets/chemistry , Perilipin-5/metabolism , Sirtuin 1/metabolism , Allosteric Regulation , Animals , Biological Transport , Cell Line , Cells, Cultured , Diet , Fatty Acids/metabolism , Lipase/metabolism , Male , Mice, Inbred C57BL , Olive Oil , Perilipin-5/physiology , Peroxisome Proliferator-Activated Receptor Gamma Coactivator 1-alpha/metabolism , Transcription, GeneticABSTRACT
The amplitude of circadian rhythms dampens with age, but Levine et al. (2020) now show that nicotinamide adenine dinucleotide (NAD+) can restore robust circadian gene expression and behavior in aged mice through SIRT1-dependent deacetylation of the core clock protein PER2.
Subject(s)
Circadian Rhythm/genetics , Period Circadian Proteins/metabolism , ARNTL Transcription Factors/genetics , Age Factors , Animals , Circadian Clocks/physiology , Circadian Rhythm/physiology , Cytokines/metabolism , Humans , Mice , NAD/metabolism , Period Circadian Proteins/genetics , Sirtuin 1/metabolism , Sirtuins/metabolismABSTRACT
Resveratrol is a natural product associated with wide-ranging effects in animal and cellular models, including lifespan extension. To identify the genetic target of resveratrol in human cells, we conducted genome-wide CRISPR-Cas9 screens to pinpoint genes that confer sensitivity or resistance to resveratrol. An extensive network of DNA damage response and replicative stress genes exhibited genetic interactions with resveratrol and its analog pterostilbene. These genetic profiles showed similarity to the response to hydroxyurea, an inhibitor of ribonucleotide reductase that causes replicative stress. Resveratrol, pterostilbene, and hydroxyurea caused similar depletion of nucleotide pools, inhibition of replication fork progression, and induction of replicative stress. The ability of resveratrol to inhibit cell proliferation and S phase transit was independent of the histone deacetylase sirtuin 1, which has been implicated in lifespan extension by resveratrol. These results establish that a primary impact of resveratrol on human cell proliferation is the induction of low-level replicative stress.
Subject(s)
Cell Proliferation/drug effects , DNA Replication/drug effects , Resveratrol/pharmacology , CRISPR-Cas Systems , Cell Line , Drug Resistance/genetics , Humans , Hydroxyurea/pharmacology , Jurkat Cells , Nucleotides/metabolism , S Phase Cell Cycle Checkpoints/drug effects , Sirtuin 1/metabolism , Stilbenes/pharmacologyABSTRACT
Aire is a transcriptional regulator that induces the promiscuous expression of thousands of tissue-restricted antigens (TRAs) in medullary thymic epithelial cells (mTECs), a step critical for the induction of immunological self-tolerance. Studies have offered molecular insights into how Aire operates, but more comprehensive understanding of this process still remains elusive. Here we found abundant expression of the protein deacetylase Sirtuin-1 (Sirt1) in mature Aire(+) mTECs, wherein it was required for the expression of Aire-dependent TRA-encoding genes and the subsequent induction of immunological self-tolerance. Our study elucidates a previously unknown molecular mechanism for Aire-mediated transcriptional regulation and identifies a unique function for Sirt1 in preventing organ-specific autoimmunity.