[Is Biological Aging a Treatable Disease? A Consideration Based on Proposed Mechanisms of Aging].

In view of the current claim by many researchers that biological aging is a treatable disease, the possibility is discussed whether the claim is realistic, based on several proposed mechanisms of aging. The definition of biological aging is stated referring to physiological aging and pathological aging, since biological aging must be defined for the discussion of whether it can be cured. Aging in animal model is compared with that in humans in terms of common age-associated phenotypes. Major proposed mechanisms of aging are next examined including Genome Instability Theory of aging, Free Radical or Oxidative Stress Theory of Aging, Mitochondrial Theory of Aging, Error Catastrophe Theory of Aging/Translational Error Theory of Aging, Altered Protein Theory of Aging/Proteostasis Theory of Aging, and Epigenetic Theory of Aging. Finally, we discuss whether treatment of aging as a disease is realistic in comparison with possible lifespan extension by retardation of biological aging.

DNA methylation clock DNAmFitAge shows regular exercise is associated with slower aging and systemic adaptation.

DNAmPhenoAge, DNAmGrimAge, and the newly developed DNAmFitAge are DNA methylation (DNAm)-based biomarkers that reflect the individual aging process. Here, we examine the relationship between physical fitness and DNAm-based biomarkers in adults aged 33-88 with a wide range of physical fitness (including athletes with long-term training history). Higher levels of VO2max (ρ = 0.2, p = 6.4E - 4, r = 0.19, p = 1.2E - 3), Jumpmax (p = 0.11, p = 5.5E - 2, r = 0.13, p = 2.8E - 2), Gripmax (ρ = 0.17, p = 3.5E - 3, r = 0.16, p = 5.6E - 3), and HDL levels (ρ = 0.18, p = 1.95E - 3, r = 0.19, p = 1.1E - 3) are associated with better verbal short-term memory. In addition, verbal short-term memory is associated with decelerated aging assessed with the new DNAm biomarker FitAgeAcceleration (ρ: - 0.18, p = 0.0017). DNAmFitAge can distinguish high-fitness individuals from low/medium-fitness individuals better than existing DNAm biomarkers and estimates a younger biological age in the high-fit males and females (1.5 and 2.0 years younger, respectively). Our research shows that regular physical exercise contributes to observable physiological and methylation differences which are beneficial to the aging process. DNAmFitAge has now emerged as a new biological marker of quality of life.

[Roles of Basic Subjects in Pharmacist Education].

As a teacher of biochemistry in a school of pharmacy, a basic subject in pharmacist education, I try to include applied topics such as the biochemical mechanisms of diseases and side effects of medicines in relation to basic knowledge of biochemistry for advanced subjects that students will learn in later years. In aging societies, many people visiting community pharmacies are elderly who tend to have health concerns other than diseases diagnosed by physicians. If asked, community pharmacists should be able to give advice on potential problems patients might have, in addition to giving explanations of medicines prescribed. Basic subjects covered in university pharmacy courses should be the most useful in such community settings.

Exercise effects on physiological function during aging.

The decrease in cognitive/motor functions and physical abilities severely affects the aging population in carrying out daily activities. These disabilities become a burden on individuals, families and society in general. It is known that aging conditions are ameliorated with regular exercise, which attenuates the age-associated decline in maximal oxygen uptake (VO2max), production of reactive oxygen species (ROS), decreases in oxidative damage to molecules, and functional impairment in various organs. While benefits of physical exercise are well-documented, the molecular mechanisms responsible for functional improvement and increases in health span are not well understood. Recent findings imply that exercise training attenuates the age-related deterioration in the cellular housekeeping system, which includes the proteasome, Lon protease, autophagy, mitophagy, and DNA repair systems, which beneficially impacts multiple organ functions. Accumulating evidence suggests that exercise lessens the deleterious effects of aging. However, it seems unlikely that systemic effects are mediated through a specific biomarker. Rather, complex multifactorial mechanisms are involved to maintain homeostatic functions that tend to decline with age.

Exogenous nicotinamide supplementation and moderate physical exercise can attenuate the aging process in skeletal muscle of rats.

Nicotinamide (NAM) could enhance the availability of NAD+ and be beneficial to cell function. However, NAM can inhibit the activities of SIRT1 and PARP. The effect of NAM supplementation on the aging process is not well known. In the present study exogenous NAM (1-0.5% in drinking water) was supplemented for 5 weeks and in the last 4 weeks moderate treadmill running was given to 5 mo and 28 mo old rats. The content of SIRT1 was not effected by NAM treatment alone. However, the activity of SIRT1, judged from the acetylated p53/p53 ratio, increased in both NAM treated age groups, suggesting beneficial effects of exogenous NAM. This was confirmed by the finding of increased PGC-1α and pCREB/CREB ratio in the gastrocnemius muscle of old but not young NAM treated animals. Our data suggest NAM administration can attenuate the aging process in skeletal muscle of rats, but NAM administration together with exercise training might be too great challenge to cope with in the old animals, since it leads to decreased levels of SIRT1.

Voluntary Exercise Can Ameliorate Insulin Resistance by Reducing iNOS-Mediated S-Nitrosylation of Akt in the Liver in Obese Rats.

Voluntary exercise can ameliorate insulin resistance. The underlying mechanism, however, remains to be elucidated. We previously demonstrated that inducible nitric oxide synthase (iNOS) in the liver plays an important role in hepatic insulin resistance in the setting of obesity. In this study, we tried to verify our hypothesis that voluntary exercise improves insulin resistance by reducing the expression of iNOS and subsequent S-nitrosylation of key molecules of glucose metabolism in the liver. Twenty-one Otsuka Long-Evans Tokushima Fatty (OLETF) rats, a model of type 2 diabetes mellitus, and 18 non-diabetic control Long-Evans Tokushima Otsuka (LETO) rats were randomly assigned to a sedentary group or exercise group subjected to voluntary wheel running for 20 weeks. The voluntary exercise significantly reduced the fasting blood glucose and HOMA-IR in the OLETF rats. In addition, the exercise decreased the amount of iNOS mRNA in the liver in the OLETF rats. Moreover, exercise reduced the levels of S-nitrosylated Akt in the liver, which were increased in the OLETF rats, to those observed in the LETO rats. These findings support our hypothesis that voluntary exercise improves insulin resistance, at least partly, by suppressing the iNOS expression and subsequent S-nitrosylation of Akt, a key molecule of the signal transduction pathways in glucose metabolism in the liver.

Exercise training increases anabolic and attenuates catabolic and apoptotic processes in aged skeletal muscle of male rats.

Aging results in significant loss of mass and function of the skeletal muscle, which negatively impacts the quality of life. In this study we investigated whether aerobic exercise training has the potential to alter anabolic and catabolic pathways in the skeletal muscle. Five and twenty eight month old rats were used in the study. Aging resulted in decreased levels of follistatin/mTOR/Akt/Erk activation and increased myostatin/Murf1/2, proteasome subunits, and protein ubiquitination levels. In addition, TNF-α, reactive oxygen species (ROS), p53, and Bax levels were increased while Bcl-2 levels were decreased in the skeletal muscle of aged rats. Six weeks of exercise training at 60% of VO2max reversed the age-associated activation of catabolic and apoptotic pathways and increased anabolic signaling. The results suggest that the age-associated loss of muscle mass and cachexia could be due to the orchestrated down-regulation of anabolic and up-regulation of catabolic and pro-apoptotic processes. These metabolic changes can be attenuated by exercise training.

Alterations in the mutagenicity and mutation spectrum induced by benzo[a]pyrene instilled in the lungs of gpt delta mice of various ages.

INTRODUCTION: To examine whether the mutagenic potential of lung exposure to air-borne environmental mutagens is age dependent, we administered 1 mg of benzo[a]pyrene intratracheally to 11- and 24-month old (middle-aged and old, respectively) gpt delta transgenic mice that harbor gpt (guanine phosphoribosyltransferase) genes integrated in the genomic DNA as a target for mutation detection, and then analyzed the benzo[a]pyrene-induced and spontaneous in vivo mutations and mutation spectrum in the lungs. RESULTS: The mutant frequencies in the lungs of the 11- and 24-month-old control (vehicle-treated) gpt delta mice were 1.14 ± 0.22 × 10(-5) and 1.00 ± 0.20 × 10(-5), respectively, which are significantly higher than that observed for the control 3-month-old (young) mice (0.59 ± 0.13 × 10(-5)) in our previous studies, indicating that spontaneous mutation in the lung increases with age. The mutant frequencies in 11- and 24-month-old mice treated with benzo [a] pyrene were 1.5- and 2.3-fold, respectively, that of the age-matched control mice, and 4.3-fold that of the 3-month-old mice in our previous studies. Analysis of mutation spectra showed that both G:C to A:T transitions and G:C to T:A transversions were predominant in the lungs of control mice at all ages. In benzo [a] pyrene-treated mice in our previous studies, G:C to T:A transversions were the predominant type of mutation (55 %) at 3 months. Here we found that their frequency was dramatically reduced to 18 % by 24 months, and the G:C to A:T transitions became the predominant type of mutation in 24-month-old mice (41 % [16 % at CpG sites]). CONCLUSIONS: Our findings suggest that susceptibility to benzo[a]pyrene is highest in young mice and is elevated again in old age. The elevation of G:C to A:T transitions was observed following benzo [a] pyrene administration in the lungs of aged mice, and accelerated cytidine deamination is speculated to contribute to this elevation.

Cardiorespiratory fitness, body mass index, and cancer mortality: a cohort study of Japanese men.

BACKGROUND: The aim of this study is to investigate the independent and joint effects of cardiorespiratory fitness (CRF) and body mass index (BMI) on cancer mortality in a low body mass index population. METHODS: We evaluated CRF and BMI in relation to cancer mortality in 8760 Japanese men. The median BMI was 22.6 kg/m2 (IQR: 21.0-24.3). The mean follow-up period was more than 20 years. Hazard ratios and 95% CI were obtained using a Cox proportional hazards model while adjusting for several confounding factors. RESULTS: Using the 2nd tertile of BMI (21.6-23.6 kg/m2) as reference, hazard ratios and 95% CI for the lowest tertile of BMI (18.5-21.5) were 1.26 (0.87-1.81), and 0.92 (0.64-1.34) for the highest tertile (23.7-37.4). Using the lowest tertile of CRF as reference, hazard ratios and 95% CIs for 2nd and highest tertiles of CRF were 0.78 (0.55-1.10) and 0.59 (0.40-0.88). We further calculated hazard ratios according to groups of men cross-tabulated by tertiles of CRF and BMI. Among men in the second tertile of BMI, those belonging to the lowest CRF tertile had a 53% lower risk of cancer mortality compared to those in the lowest CRF tertile (hazard ratio: 0.47, 95% CI: 0.23-0.97). Among those in the highest BMI tertile, the corresponding hazard ratio was 0.54 (0.25-1.17). CONCLUSION: These results suggest that high CRF is associated with lower cancer mortality in a Japanese population of men with low average BMI.

Dietary restriction increases protein acetylation in the livers of aged rats.

BACKGROUND: Dietary restriction (DR) is a well-established biological method for lifespan extension in various organisms by delaying the progression of age-related disorders. With regard to its molecular mechanisms, a family of NAD-dependent protein deacetylases, such as sirtuins, is considered to mediate DR-induced lifespan extension in some lower organisms. Furthermore, the effects of DR on sirtuins (e.g. SIRT1, SIRT2, SIRT3, and SIRT5) have also been reported in mammals. However, the relationship between sirtuins and DR-associated longevity in mammals is still not clear. In addition, ageing and DR-associated changes in cellular protein acetylation have not been fully elucidated, especially in DR-aged animals. OBJECTIVE: We aimed to elucidate the effect of ageing and DR on cellular protein acetylation in young and aged rats. METHODS: Fischer 344 rats were subjected to DR for 7.5 or 25.5 months from 1.5 months of age. Protein acetylation status in tissues was analyzed by Western blotting, subcellular fractionation, and immuno-pull-down assay. We also analyzed the quantitative changes in some related deacetylases and an acetyltransferase. RESULTS: Acetylation of multiple proteins in the liver of young and aged rats decreased slightly with ageing and increased markedly under DR. The results of subcellular fractionation revealed that the DR-induced increase in protein acetylation was more prominent in extranuclear proteins than in nuclear proteins, indicating that acetylation is global, but protein-specific. This was further confirmed in the results of immune-pull-down assays for mitochondrial acetylated proteins. Cellular protein acetylation is regulated by multiple factors, including various deacetylases and acetyltransferases. With regard to the possible mechanisms of DR-induced increases in protein acetylation, we observed that DR increased SIRT3 expression in the liver of young and aged rats. Expression of the mitochondrial protein acetyltransferase GCN5L1 significantly increased with ageing but did not respond to DR. CONCLUSIONS: The increased acetylation of extranuclear proteins may be involved in DR-induced anti-ageing effects including longevity. However, the mechanisms underlying the changes in protein acetylation might not result from quantitative changes in mitochondrial sirtuins and the mitochondrial protein acetyltransferase.

Effects of regular exercise on neutrophil functions, oxidative stress parameters and antibody responses against 4-hydroxy-2-nonenal adducts in middle aged humans.

Regular exercise has recognized health benefits, partly because it reportedly lowers the levels of the oxidation products of proteins and DNA at rest, in contrast with the effect of acute exercise. However, when we compared oxidative response markers in active middle-aged subjects with those in sedentary ones, the level of urinary 8-OHdG was higher in active subjects. Because neutrophils are the first line of defense against a variety of infectious diseases, we then compared the cell density, functions and apoptosis of neutrophils in active subjects with those in sedentary ones. The cell density of neutrophils and phagocytosis of opsonized zymosan by neutrophils were higher in active subjects, being similar with the reported effects of acute exercise. To determine any beneficial effects of oxidative stress in active subjects, we then compared the levels of antibodies against 4-hydroxy-2-nonenal adducts in active subjects with those in sedentary ones, because 4-hydroxy-2-nonenal is one of the most common bioactive aldehyde products of oxidative stress, and because the IgM class of antibodies against oxidized low-density lipoprotein is associated with atheroprotective properties. The level of the IgM but not the IgG class of antibodies against 4-hydroxy-2-nonenal adducts was higher in active subjects. Overall, this study revealed that our active middle-aged subjects showed both oxidative responses and a higher IgM response to reactive carbonyl derivatives, possibly providing a basis for a health benefit by exercise in our active subjects.

Redox-regulating sirtuins in aging, caloric restriction, and exercise.

The consequence of decreased nicotinamide adenine dinucleotide (NAD(+)) levels as a result of oxidative challenge is altered activity of sirtuins, which, in turn, brings about a wide range of modifications in mammalian cellular metabolism. Sirtuins, especially SIRT1, deacetylate important transcription factors such as p53, forkhead homeobox type O proteins, nuclear factor κB, or peroxisome proliferator-activated receptor γ coactivator 1α (which controls the transcription of pro- and antioxidant enzymes, by which the cellular redox state is affected). The role of SIRT1 in DNA repair is enigmatic, because it activates Ku70 to cope with double-strand breaks, but deacetylation of apurinic/apyrimidinic endonuclease 1 and probably of 8-oxoguanine-DNA glycosylase 1 decreases the activity of these DNA repair enzymes. The protein-stabilizing effects of the NAD+-dependent lysine deacetylases are readily related to housekeeping and redox regulation. The role of sirtuins in caloric restriction (CR)-related longevity in yeast is currently under debate. However, in mammals, it seems certain that sirtuins are involved in many cellular processes that mediate longevity and disease prevention via the effects of CR through the vascular, neuronal, and muscular systems. Regular physical exercise-mediated health promotion also involves sirtuin-regulated pathways including the antioxidant-, macromolecular damage repair-, energy-, mitochondrial function-, and neuronal plasticity-associated pathways. This review critically evaluates these findings and points out the age-associated role of sirtuins.

Age-associated declines in mitochondrial biogenesis and protein quality control factors are minimized by exercise training.

A decline in mitochondrial biogenesis and mitochondrial protein quality control in skeletal muscle is a common finding in aging, but exercise training has been suggested as a possible cure. In this report, we tested the hypothesis that moderate-intensity exercise training could prevent the age-associated deterioration in mitochondrial biogenesis in the gastrocnemius muscle of Wistar rats. Exercise training, consisting of treadmill running at 60% of the initial Vo(2max), reversed or attenuated significant age-associated (detrimental) declines in mitochondrial mass (succinate dehydrogenase, citrate synthase, cytochrome-c oxidase-4, mtDNA), SIRT1 activity, AMPK, pAMPK, and peroxisome proliferator-activated receptor gamma coactivator 1-α, UCP3, and the Lon protease. Exercise training also decreased the gap between young and old animals in other measured parameters, including nuclear respiratory factor 1, mitochondrial transcription factor A, fission-1, mitofusin-1, and polynucleotide phosphorylase levels. We conclude that exercise training can help minimize detrimental skeletal muscle aging deficits by improving mitochondrial protein quality control and biogenesis.

Dietary restriction increases site-specific histone H3 acetylation in rat liver: possible modulation by sirtuins.

We studied dietary restriction (DR) related changes of site-specific acetylation of histone H3 in rat livers to explore a possible link to histone modifications and sirtuin levels with anti-aging effects of DR. The acetylation at lysine residue 9, 27 and 56 in H3 was 20-30% higher in DR animals compared with ad libitum fed counterparts. SIRT6, one of histone deacetylases, was significantly decreased by DR and thereby may be involved in an increase in the histone acetylation. Our findings suggest that upregulation of chromatin activities through increased histone acetylation is a mechanism of anti-aging effects of DR.

Nitric oxide: is it the cause of muscle soreness?

Skeletal muscle hosts all of the isoforms of nitric oxide synthase (NOS). It is well documented that nitric oxide (NO) regulates force generation and satellite cell activation, and therefore, damage repair of skeletal muscle. NO can also activate nociceptors of C-fibers, thereby causing the sensation of pain. Although delayed-onset of muscle soreness (DOMS) is associated with decreased maximal force generation, pain sensation and sarcomere damage, there is a paucity of research linking NO and DOMS. The present mini-review attempts to elucidate the possible relationship between NO and DOMS, based upon current literature.

Age-associated neurodegeneration and oxidative damage to lipids, proteins and DNA.

Lipids, proteins and DNA in the central nervous system have a high sensitivity to oxidative stress. Reactive oxygen species (ROS)-induced damage increases with aging, especially in the last quarter of the life span. The so called base level of oxidative modification of lipids could be important to cell signaling, and membrane remodeling, but the ROS-mediated post translation modifications of proteins could be important to the homeostasis of protein turnover. Low levels of 8-oxo-7,8-dihydroguanine (8-oxoG) might be necessary for transcription. A high level of accumulation of lipid peroxidation, oxidative protein damage or 8-oxoG, on the other hand, accelerates the progress of aging and neurodegenerative diseases. Therefore, agents that induce the activity of repair enzymes, such as Ca(2(+))-independent phospholipase A(2) (iPLA(2)beta), methionine sulfoxide reductase, and 8-oxoguanine DNA glycosylase, or the activity of enzymes that could prevent the accumulation of oxidized, toxic proteins, such as proteasome, Lon protease, neprilysin or insulin degrading enzyme, may act as potential therapeutic tools to slow the aging process and the progress of neurodegenerative diseases.

Biological significance of protein modifications in aging and calorie restriction.

By virtue of the progress in proteomics, the involvement of posttranslational modifications in aging has been more clearly demonstrated in recent years. We describe here that (1) carbonylation, a hallmark of protein oxidation in general, is paradoxically decreased in histone with aging and increased by calorie restriction (CR), (2) acetylation of lysine 9 and phosphorylation of serine 10 in histone H3 are decreased and increased, respectively, with aging, and (3) the acetylation level of multiple extranuclear proteins decreases significantly with aging, and the change was not only retarded but increased remarkably by CR in rat liver. Based on these findings, we discuss possible implications of the posttranslational protein modifications in biochemical processes underlying aging and CR-induced extension of life span.

Aging and exercise affect the level of protein acetylation and SIRT1 activity in cerebellum of male rats.

Aging is associated with a gradual decline in cognitive and motor functions, the result of complex biochemical processes including pre- and posttranslational modifications of proteins. Sirtuins are NAD(+) dependent protein deacetylases. These enzymes modulate the aging process by lysine deacetylation, which alters the activity and stability of proteins. Exercise can increase mean life-span and improve quality of life. Data from our laboratories revealed that 4 weeks of treadmill running improves performance in the Morris Maze test for young (4 months, old) but not old (30 months, old) male rats, and the exercise could not prevent the age-associated loss in muscle strength assessed by a gripping test. The positive correlation between protein acetylation and the gripping test suggests that the age-dependent decrease in relative activity of SIRT1 in the cerebellum impairs motor function. Similarly to the acetylation level of total proteins, the acetylation of ά -tubulin is also increased with aging, while the effect of exercise training was not found to be significant. Moreover, the protein content of nicotinamide phosphoribosyltransferase, one of the key enzymes of NAD biosynthesis, decreased in the young exercise group. These data suggest that aging results in decreased specific activity of SIRT1 in cerebellum, which could lead to increased acetylation of protein residues, including ά-tubulin, that interfere with motor function.

Complete lack of vitamin C intake generates pulmonary emphysema in senescence marker protein-30 knockout mice.

Vitamin C (VC) is a potent antioxidant and plays an essential role in collagen synthesis. As we previously reported, senescence marker protein-30 (SMP30) knockout (KO) mice cannot synthesize VC due to the genetic disruption of gluconolactonase (i.e., SMP30). Here, we utilized SMP30 KO mice deprived of VC and found that VC depletion caused pulmonary emphysema due to oxidative stress and a decrease of collagen synthesis by the third month of age. We grew SMP30 KO mice and wild-type (WT) mice on VC-free chow and either VC water [VC(+)] or plain water [VC(-)] after weaning at 4 wk of age. Morphometric findings and reactive oxygen species (ROS) in the lungs were evaluated at 3 mo of age. No VC was detected in the lungs of SMP30 KO VC(-) mice, but their ROS increased 50.9% over that of the VC(+) group. Moreover, their collagen content in the lungs markedly decreased, and their collagen I mRNA decreased 82.2% compared with that of the WT VC(-) group. In the SMP30 KO VC(-) mice, emphysema developed [21.6% increase of mean linear intercepts (MLI) and 42.7% increase of destructive index compared with VC(+) groups], and the levels of sirtuin 1 (Sirt1) decreased 16.8%. However, VC intake increased the MLI 16.2% and thiobarbituric acid reactive substances 22.2% in WT mice, suggesting that an excess of VC can generate oxidative stress and may be harmful during this period of lung development. These results suggest that VC plays an important role in lung development through affecting oxidant-antioxidant balance and collagen synthesis.