| pha-4 | defective PHArynx development 4 | pha-4 is required for multiple forms of DR. RNAi of pha-4 completely cancels out the lifespan extension of eat-2 mutation. Mutants of pha-4 do not respond to bacterial DR. Therefore, loss of pha-4 completely blocks the response to varying food concentration. Moreover, pha-4 expression is increased in response to DR in wild-type. pha-4 overexpression increases longevity of wild-type only slightly, but significant that of daf-16 mutants. The response to DR involves the PHA-4-dependent expression of sod-1, sod-2 and sod-5. Reduction of pha-4 does not suppress the long lifespan of daf-2 mutants or animals with defective electron transport chain [17476212]. IF significantly extends lifespan of pha-4 [19079239]. sDR extends lifespan of mutants with a temperature sensitive allele of pha-4 or pha-4 RNAi knockdown, but not daf-16 RNAi [19239417]. PHA-4 may play a role in the life-extending effects of dietary restriction. RNAi of pha-4 decreases lifespan of wild-type worms, but not of daf-2 mutants or of animals with defective electron transport chains. | Nematode |
| PNC1 | Pyrazinamidase/NiCotinamidase 1 | Cells with 5 copies of PNC1 have a 70% longer replicative lifespan which is cancelled out by SIR2 deletion. PNC1 is upregulated under glucose DR [12736687]. Pnc1 reduces cellular nicotinamide levels, a product and noncompetitive inhibitor of Sir2 deacetylation reaction. Overexpression of PNC1 suppresses the effect of exogenously added nicotinamide on Sir2-dependent silencing at HM loci, telomeres and rDNA loci [12736687; 14729974]. Pnc1 catalyses the breakdown of nicotinamide to nicotinate and ammonia [12736687]. Deletion of PNC1 shortens replicative lifespan approximately by 10% [12736687] and largely prevents replicative lifespan extension of 0.5% glucose restriction. 0.5% glucose restriction slightly extends median replicative lifespan (by 10 - 15%) but not maximum replicative lifespan in pnc1Delta [14724176]. PNC1 overexpression suppresses the inhibitory effect of exogenously added NAM on silencing, lifespan, and Hst1-mediated transcriptional repression [14729974]. Increased expression of PNC1 is both necessary and sufficient for replicative lifespan extension by DR and low-intensity stress. Under non-stressing conditions (2% glucose, 30 degree Celsius), a strain with additional copies of PNC1 (5XPNC1) has 70% longer replicative lifespan than the wild-type and some cells live for more than 70 divisions. Neither DR nor heat stress further increase the lifespan of the 5XPNC1 strain [12736687]. PNC1 deletion decreases chronological lifespan [17110466]. | Budding yeast |
| sir-2.1 | Yeast SIR related 1 | sir-2.1 deletion slightly reduces lifespan of wild-type [16860373]. sir-2.1 overexpression extends lifespan by about 50% and this lifespan extension depends on DAF-16 activity as it is suppressed by mutation in daf-16 and it does not synergize with daf-2 [11242085]. sir-2.1 suppresses longevity of unc-13 and eat-2, but not daf-2 or unc-64 mutants. sir-2.1 is therefore partially required for lifespan extension from mutation of eat-2 [16860373], but is completely independent for lifespan extension from DR using a reduced feeding protocol [Kaeberlein et al. in press]. sDR increases lifespan of wild-type and sir-2.1 mutants to the same extent [19239417].
Overrexpression of sir-2.1 synergizes with TGF-beta mutation (daf-4 and daf-1) for dauer formation [11242085]. | Nematode |
| SIR2 | Silent Information Regulator 2 | Deletion of SIR2 shortens replicative lifespan by approximately 30%. Integration of a second copy of SIR2 into the wild-type strain leads to an extension of replicative lifespan by around 35% in W303R strain [10521401]. Deletion of SIR2 causes genomic instability at rDNA array [2647300] and shortens replicative lifespan by 50% [11000115]. 0.5% glucose restriction fails to increase the short lifespan of sir2Delta [11000115] probably duo to hyperaccumulations of extrachromosomal rDNA circles (ERCs) [16311627]. 0.1% glucose restriction extends replicative lifespan of sir2 mutants [12213553]. 0.5, 0.1 and 0.05% glucose restriction are able to increase lifespan of sir2;fob1 double mutant to a greater extent than in wild-type [15328540]. 0.05% glucose restriction further extends replicative lifespan of SIR2 overexpression mutant [15328540]. Sir2 blocks extreme chronological lifespan extension as the lack of Sir2 along with DR and/or mutations in the yeast AKT homolog, Sch9, or Ras pathways causes a dramatic chronological lifespan extension (6-fold) [16286010]. Sir2 inhibits formation of ERCs and acts on histones as well metabolic enzymes among others. Overexpression extends replicative lifespan in several strains, but not in PSY316 [15684413].
Chronological lifespan of sir2 deletion mutant is significantly extended compared with wild-type in water (extreme DR) but not in saturated cultures containing 2% glucose (ad libitum).
SIR2 mutants are defective for telomere [1913809] and HM silencing [6098447; 3297920]. have increased rDNA recombination [2647300] and a loss of rDNA silencing [9009207; 9009206].
| Budding yeast |
| Sir2 | — | Overexpression of Sir2 (alias dSir2) extends lifespan by up to 57% and specifically median lifespan by 40-60%, whereas a decrease in Sir2 activity by mutation blocks the life-extending effect of caloric reduction or rpd3 mutations [15520384]. rpd3 mutants fed normal food and wild-type fed a low-calorie diet increase dSir2 expression two-fold [12459580]. Sir2 mutation does not reduce lifespan under AL. Ubiquitous Sir2 overexpression causes a 4-fold increase in Sir2 mRNA expression and an up to 57% increase in average lifespan (29% for females and 18% for males). A 10 - 20% increase in Sir2 mRNA levels causes no lifespan extension. High levels of Sir2 protein is found in nuclei of neurons and in nuclei and cytoplasm of fat body cells. Neuronal Sir2 overexpression extends average lifespan by 52% in females and 20% in males. Motor-neuronal specific expression fails to cause lifespan extension. Flies with no or with several decreased Sir2 gene function have no lifespan extension under DR. DR fails to cause further increase in lifespan or even reduces lifespan toward normal of Sir2 overexpression mutants. Mild Sir2 overexpression in the fat-body extends lifespan and reduces relative body fat content in both males and females [22661237].
Sir2 in the adult fat body regulates longevity in a diet-depending manner. A diet-dependent lifespan phenotype of Sir2 perturbations (both knockdown and overexpression) in the fat-body, but not in muscles, negates the effects of background genetic mutants. Sir2 knockdown abrogates fat-body dFoxo-dependent lifespan extension [23246004].
Decreased expression of Sir2 and Sir2-like genes in all cells causes lethality during development. Suppression of the Sir2 in neurons decreases the median lifespan by 10-30%, while ubiquitinous silinecing of the Sir2-like genes shortens lifespan. The effects are server at 28°C that at 25°C [17159295]. | Fruit fly |
| skn-1 | SKiNhead 1 | RNA interference of or mutations in skn-1 prevent the life-extension effects of dietary restriction [17538612]. skn-1 transgenes that overexpress a constitutive nuclear form of SKN-1 in the intestine extend the mean lifespan by 5-21%, independently of DAF-16 [18358814]. skn-1 mutation does not alter lifespan under AL, but cancels out the lifespan extension effect of lDR or food variation at all. Response to lDR in skn-1 mutant is restored by ectopic expression of skn-1 in ASI neurons and gut. Ectopic expression of skn-1b in ASI neurons rescued lDR longevity defects of skn-1. Ablation of ASI neurons completely suppresses the response to DR in wild-type or daf-16 mutants and cause a small increase in basal longevity of wild-type but not daf-16 mutants. lDR significantly increases SKN-1 expression in ASI neurons. lDR worms exhibit elevated respiration, which is absent in skn-1 mutants. skn-1 is necessary for increased respiration and the increase in respiration is necessary for lDR longevity effect, because two different inhibitors of mitochondrial electron transport chain complex III, myxothiazol and antimycin, suppress lDR longevity without shortening lifespan under AL. In contrast, the long life of a daf-2 mutant is not affected by antimycin. Some isoforms of SKN-1 are expressed from an operon downstream of bec-1. Beclin-1 mediates autophagy induced by nutrient deprivation. Therefore, skn-1 might be regulated by nutritional stress [17538612]. IF significantly extends lifespan of skn-1 mutants [19079239]. sDR extends lifespan of a skn-1 loss-of-function mutant (which displays a premature stop codon in all three isoforms) and wild-type to a similar extent [19239417].
skn-1(zu67) mutation decreases mean, median, and maximum lifespan by 11-23, 13-28 and 12-23%, respectively, and totally cancels out lifespan extension by ragc-1 RNAi [22560223].
| Nematode |
| SRX1 | SulfiRedoXin 1 | Extra copy of SRX1 counteracts age-related hyperoxidation of Tsa1 and extends replicative lifespan by 15 - 20% in a TSA1-dependent manner. Replicative lifespan extension in sir2;fob1 double mutant by DR is reduced by SRX1 deletion. Wild-type cells require SRX1 to fully extend lifespan. DR fails to further extend replicative lifespan of cells carrying an extra copy of SRX1. Mutation in CDC35 (adenylate cyclase), a genetic mimetic of DR, is dependent on SRX1 to extend replicative lifespan [21884982]. | Budding yeast |
| Thor | — | Null mutation in Thor (alias d4E-BP) causes a significant decrease in longevity (-25% median lifespan in males). Thor is strongly upregulated during starvation. foxo and Thor null mutants are compromised in stress resistant. Stress resistance of foxo null mutants is rescued by Thor overexpression [16055649]. Thor is upregulated on the protein level in a foxo-independent manner upon DR, while it is transcriptional induced in a foxo-dependent fashion by starvation. Thor null mutants cancel out DR-induced lifespan extension, because mutants exhibit a diminished change in lifespan when nutrient conditions were varied. Ubiquitously expression of Thor rescued DR response in females and males. Thor null mutants have a wild-type similar reduction in egg production upon DR. Ubiquitously overexpression of wild-type Thor causes no change under AL, but an activated allele (with more than 3-fold increased binding activity to delF4E) significantly extends lifespan of females (weak allele) and females as well as males (strong allele). Mean lifespan is extended by 11 to 40%. Median lifespan of males and females is enhanced by by 11 and 22%, respectively. Maximum lifespan is extended by 16 and 18% for males and females, respectively. Under DR (0.25% YE) there is no lifespan extension, beyond the effect of DR alone, in all (wild-type, weak and strong) Thor alleles [19804760].
Lifespan of animals with increased Pten and 4E-BP activity in muscle exhibit and extended mean and maximum lifespan by 20% and 15.8% [21111239]. | Fruit fly |
| trx-1 | ThioRedoXin 1 | Thioredoxins regulate many cellular redox processes. trx-1 is mainly associated with neurons and is expressed in ASJ ciliated sensory neurons and to some extent also on the posterior-most internal cells. trx-1 reduces protein disulfides in the presence of a heterologous thioredoxin reductase. trx-1 null mutant display reduced mean and maximum lifespan [16387300]. Mutants with a deletion in the trx-1 gene display a decrease in lifespan and are sensitive to oxidative stress [16324156]. trx-1 overexpression extends lifespan in wild-type but not in eat-2 mutants. trx-1 deletion completely suppresses the lifespan extension caused by eat-2 mutation, but only partially suppresses that by daf-2 or osm-5 mutations. Ectopic expression of trx-1 in ASJ neurons (but not in the intestine) in trx-1 mutants rescues the lifespan-extension conferred by eat-2 mutation. trx-1 overexpression extends lifespan of wild-type but not in eat-2 mutants. trx-1 deletion almost completely suppresses lifespan extension induced by dietary deprivation (DD). DD upregulates trx-1 expression in ASJ neurons. DR activates trx-1 in ASJ neurons which in turn triggers a trx-1-dependent non-cell autonomous mechanism to extend adult lifespan [21334311].
| Nematode |
| ucp2 | uncoupling protein 2 | Overexpression of zebrafish's ucp2 in nematode increases mean, median, and maximum lifespan by 42, 40, and 26%, which is non-additive with sDR [22737090]. | — |
| VMA1 | Vacuolar Membrane Atpase 1 | Overexpression of VMA1 increases vacuolar acidity and suppresses age-induced mitochondrial dysfunction of aged cells (17 or 18 cell divisions) which requires the V-ATPase activity. VMA1 overexpression significantly increases mean, median and maximum lifespan by 39 - 45%, 39 - 48% and 50 - 60%, respectively. DR (0.5% glucose restriction) does not further increase the lifespan of VMA1 overexpression strain [23172144].
| Budding yeast |
| wis1 | — | Constitutive active mutation of wis1 extends chronological lifespan and there is no further beneficial effect of DR [20075862]. | Fission yeast |
| wwp-1 | WW domain Protein (E3 ubiquitin ligase) 1 | RNA interference of wwp-1 decreases median lifespan by 9% in wild-type animals and 24% in daf-2 mutants [18006689]. Loss of wwp-1 function by RNAi or mutation reduces lifespan at 25 degree Celsius, but not 20 degree Celsius. wwp-1 overexpression extends lifespan by up to 20%. Reduced levels of wwp-1 completely suppress the extended longevity of eat-2 mutants. Lifespan of wwp-1 mutants across entire food concentration range by bacterial dilution in liquid culture or on solid plates does not noticeable change. There is no difference in wwp-1 mRNA levels under AL and DR. RNAi reduction of pha-4, but not of daf-16 suppresses increased longevity by wwp-1 overexpression. Mutations in iron sulphur component of complex III, isp-1, increases longevity by reducing mitochondrial function. wwp-1 RNAi does not suppress the extended lifespan of isp-1 mutants and has only minor suppressive effects on lifespan of another mitochondrial mutant, clk-1, and in cyc-1 RNAi treated worms. RNAi depletion of wwp-1 has no effect on long lifespan of daf-2 mutants [19553937]. | Nematode |
