| symbol | name | observation | species | | 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 | | NNT1 | Nicotinamide N-methylTransferase 1 | Deletion of NNT1 decreases mean and maximum lifespan by 9 and 19%. 0.5% glucose DR extends the mean and maximum lifespan of NNT1 deletion mutants by 35 and 40%. Overexpression of NNT1 by 5-fold extends mean and maximum replicative lifespan by 18 and 23%, which is approximately of the same magnitude as the lifespan extension obtained from DR. DR in NNT1 overexpression mutant fails to significantly affect the lifespan and only results in extended mean lifespan by 12% and reduced maximum lifespan by 11%. NNT1 overexpression increases rDNA silincing, whereas deletion decreases rDNA silencing. Overexpression of human nicotinamide N-methyltransferase also increases rDNA silencing [12736687]. | Budding yeast | | 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 | | AVT1 | Amino acid Vacuolar Transport 1 | Overexpressing or deleting AVT1 is sufficient to extend or shorten replicative lifespan, respectively [23172144].
Overexpression of AVT1 prevents mitochondrial dysfunction, prevents alterations in mitochondrial structure and ΔΨ of aged cells even through the vacuolar acidity is reduced in these cells. AVT1 overexpression extends the mean, median and maximum replicative lifespan by 28, 28, and 22%, respectively [23172144].
Deletion of AVT1 accelerates the development of age-induced mitochondrial dysfunction without effecting the kinetics of vacuolar acidity decline and prevents the suppression of mitochondrial dysfunction by VMA1 and VPH2 overexpression without affecting vacuolar acidity. AVT1 deletion decreases mean, median and maximum replicative lifespan by 21, 22, and 12%, respectively [23172144]. | Budding yeast | |
