Increased dosage of a sir-2 gene extends lifespan in Caenorhabditis elegans

Regulation of Nrf2 by Mitochondrial Reactive Oxygen Species in Physiology and Pathology

Reactive oxygen species (ROS) are byproducts of aerobic respiration and signaling molecules that control various cellular functions. Nrf2 governs the gene expression of endogenous antioxidant synthesis and ROS-eliminating enzymes in response to various electrophilic compounds that inactivate the negative regulator Keap1. Accumulating evidence has shown that mitochondrial ROS (mtROS) activate Nrf2, often mediated by certain protein kinases, and induce the expression of antioxidant genes and genes involved in mitochondrial quality/quantity control. Mild physiological stress, such as caloric restriction and exercise, elicits beneficial effects through a process known as “mitohormesis”. Exercise induces NOX4 expression in the heart, which activates Nrf2 and increases endurance capacity. Mice transiently depleted of SOD2 or overexpressing skeletal muscle-specific UCP1 exhibit Nrf2-mediated antioxidant gene expression and PGC1α-mediated mitochondrial biogenesis. ATF4 activation may induce a transcriptional program that enhances NADPH synthesis in the mitochondria and might cooperate with the Nrf2 antioxidant system. In response to severe oxidative stress, Nrf2 induces Klf9 expression, which represses mtROS-eliminating enzymes to enhance cell death. Nrf2 is inactivated in certain pathological conditions, such as diabetes, but Keap1 down-regulation or mtROS elimination rescues Nrf2 expression and improves the pathology. These reports aid us in understanding the roles of Nrf2 in pathophysiological alterations involving mtROS.

SIRT1 inhibits chemoresistance and cancer stemness of gastric cancer by initiating an AMPK/FOXO3 positive feedback loop

Chemotherapy is the standard care for patients with gastric cancer (GC); however, resistance to existing drugs has limited its success. The persistence of cancer stem cells (CSCs) is considered to be responsible for treatment failure. In this study, we demonstrated that SIRT1 expression was significantly downregulated in GC tissues, and that a low SIRT1 expression level indicated a poor prognosis in GC patients. We observed a suppressive role of SIRT1 in chemoresistance of GC both in vitro and in vivo. In addition, we found that SIRT1 eliminated CSC properties of GC cells. Mechanistically, SIRT1 exerted inhibitory activities on chemoresistance and CSC properties through FOXO3 and AMPK. Furthermore, a synergistic effect was revealed between FOXO3 and AMPK. AMPK promoted nuclear translocation of FOXO3 and enhanced its transcriptional activities. In addition, FOXO3 increased the expression level and activation of AMPKα by directly binding to its promoter and activating the transcription of AMPKα. Similar to SIRT1, low expression levels of p-AMPKα and FOXO3a are also related to the poor prognosis of GC patients. Moreover, we revealed a correlation between the expression levels of SIRT1, p-AMPKα, and FOXO3a. These findings indicated the importance of the SIRT1-AMPK/FOXO3 pathway in reversing chemoresistance and CSC properties of GC. Thus, exploring efficient strategies to activate the SIRT1-AMPK/FOXO3 pathway may lead to improving the survival of GC patients.

SIRT1 inhibits chemoresistance and cancer stemness of gastric cancer by initiating an AMPK/FOXO3 positive feedback loop

Chemotherapy is the standard care for patients with gastric cancer (GC); however, resistance to existing drugs has limited its success. The persistence of cancer stem cells (CSCs) is considered to be responsible for treatment failure. In this study, we demonstrated that SIRT1 expression was significantly downregulated in GC tissues, and that a low SIRT1 expression level indicated a poor prognosis in GC patients. We observed a suppressive role of SIRT1 in chemoresistance of GC both in vitro and in vivo. In addition, we found that SIRT1 eliminated CSC properties of GC cells. Mechanistically, SIRT1 exerted inhibitory activities on chemoresistance and CSC properties through FOXO3 and AMPK. Furthermore, a synergistic effect was revealed between FOXO3 and AMPK. AMPK promoted nuclear translocation of FOXO3 and enhanced its transcriptional activities. In addition, FOXO3 increased the expression level and activation of AMPKα by directly binding to its promoter and activating the transcription of AMPKα. Similar to SIRT1, low expression levels of p-AMPKα and FOXO3a are also related to the poor prognosis of GC patients. Moreover, we revealed a correlation between the expression levels of SIRT1, p-AMPKα, and FOXO3a. These findings indicated the importance of the SIRT1-AMPK/FOXO3 pathway in reversing chemoresistance and CSC properties of GC. Thus, exploring efficient strategies to activate the SIRT1-AMPK/FOXO3 pathway may lead to improving the survival of GC patients.

Neuroprotective Effect of Resveratrol via Activation of Sirt1 Signaling in a Rat Model of Combined Diabetes and Alzheimer's Disease

Background

Alzheimer’s disease (AD) and diabetes mellitus (DM) often coexist in patients because having one of these conditions increases risk for the other. These two diseases share several pathophysiological mechanisms, such as specific inflammatory signaling pathways, oxidative stress, and cell apoptosis. It is still unclear exactly which mechanisms associated with DM are responsible for increased AD risk. Studies have found that even transient elevation of brain Aβ levels can allow T2DM to slightly disrupt the neural milieu in a way that encourages pathologies associated with the onset of memory deficits and AD. A recent study argues that a potential common pathogenetic mechanism underlying both DM and AD is evidenced by the cooccurrence of amyloid brain legions and deposits containing both tau and Aβ in pancreatic β cells. Given these links, an investigation detailing disease mechanisms as well as treatment options for patients with cooccurring DM and AD is urgently needed. The biological effects of resveratrol relevant to DM and AD treatment include its abilities to modulate oxidative stress and reduce inflammation. A rat model of DM and concomitant AD was created for this study using intraperitoneal injection of streptozotocin and hippocampal injection of Aβ1–40 to characterize resveratrol’s potential protective action.

Results

Resveratrol significantly increased the Sirt1 expression, inhibited the memory impairment, the increased acetylcholinesterase, malondialdehyde, interleukin-1β and interleukin 6 levels, and the decreased levels of choline acetyltransferase (ChAT), superoxide dismutase (SOD), and glutathione in this rat model of diabetes and concomitant AD. The Sirt 1 inhibitor EX527 partially reversed the effects of resveratrol.

Conclusion

This study suggests that resveratrol may have a neuroprotective action through activation of Sirt1 signaling in diabetes and AD with concurrent onset.

The yin and yang faces of the mitochondrial deacetylase sirtuin 3 in age-related disorders

Aging, the most important risk factor for many of the chronic diseases affecting Western society, is associated with a decline in mitochondrial function and dynamics. Sirtuin 3 (SIRT3) is a mitochondrial deacetylase that has emerged as a key regulator of fundamental processes which are frequently dysregulated in aging and related disorders. This review highlights recent advances and controversies regarding the yin and yang functions of SIRT3 in metabolic, cardiovascular and neurodegenerative diseases, as well as the use of SIRT3 modulators as a therapeutic strategy against those disorders. Although most studies point to a protective role upon SIRT3 activation, there are conflicting findings that need a better elucidation. The discovery of novel SIRT3 modulators with higher selectivity together with the assessment of the relative importance of different SIRT3 enzymatic activities and the relevance of crosstalk between distinct sirtuin isoforms will be pivotal to validate SIRT3 as a useful drug target for the prevention and treatment of age-related diseases.

Signaling Network of Forkhead Family of Transcription Factors (FOXO) in Dietary Restriction

Dietary restriction (DR), which is defined as a reduction of particular or total nutrient intake without causing malnutrition, has been proved to be a robust way to extend both lifespan and health-span in various species from yeast to mammal. However, the molecular mechanisms by which DR confers benefits on longevity were not yet fully elucidated. The forkhead box O transcription factors (FOXOs), identified as downstream regulators of the insulin/IGF-1 signaling pathway, control the expression of many genes regulating crucial biological processes such as metabolic homeostasis, redox balance, stress response and cell viability and proliferation. The activity of FOXOs is also mediated by AMP-activated protein kinase (AMPK), sirtuins and the mammalian target of rapamycin (mTOR). Therefore, the FOXO-related pathways form a complex network critical for coordinating a response to environmental fluctuations in order to maintain cellular homeostasis and to support physiological aging. In this review, we will focus on the role of FOXOs in different DR interventions. As different DR regimens or calorie (energy) restriction mimetics (CRMs) can elicit both distinct and overlapped DR-related signaling pathways, the benefits of DR may be maximized by combining diverse forms of interventions. In addition, a better understanding of the precise role of FOXOs in different mechanistic aspects of DR response would provide clear cellular and molecular insights on DR-induced increase of lifespan and health-span.

Factors that affect the translation of dietary restriction into a longer life

Nutritional interventions, such as dietary or calorie restriction, are known to have a variety of health-promoting effects. The most impressive are the direct effects on life expectancy, which have been reproduced in many animal models. A variety of dietary restriction protocols have been described, which differ either in their macronutrient composition or in the time window for consumption. Mechanistically, the effects of dietary restriction are mediated mainly through signaling pathways that have central roles in the maintenance of cellular energy balance. Among these, target of rapamycin and insulin signaling appear to be the most important. Such nutritional interventions can have their effects in two different ways: either by direct interaction with the metabolism of the host organism, or by modulating the composition and performance of its endogenous microbiome. Various dietary restriction regimens have been identified that significantly alter the microbiome and thus profoundly modulate host metabolism. This review aims to discuss the mechanisms by which dietary restriction can affect life expectancy, and in particular the role of the microbiome.

Overexpression of CBS and CSE genes affects lifespan, stress resistance and locomotor activity in Drosophila melanogaster

Recent experimental studies highlighted the role of hydrogen sulfide (H₂S) in aging and longevity. The cystathionine ß-synthase (CBS) and cystathionine γ-lyase (CSE) are the key enzymes responsible for H₂S production. Here we investigated the geroprotective effects of CSE and CBS overexpression in Drosophila. Overexpression of CSE did not affect a lifespan and decrease (mitochondrial form of CSE) or increase (cytoplasmic form of CSE) age dynamics of locomotor activity, while overexpression of CBS increase median (by 12.5%) and maximum (by 6.9%) lifespan and locomotor activity. Increasing of both CSE and CBS expression levels resulted in thermotolerance, but the resistance to combination of arid and food-free conditions decreased. The resistance to oxidative stress (paraquat) was not affected in flies with overexpression of CBS and cytoplasmic CSE, but decreased in flies overexpressing mitochondrial form of CSE. Thus, transgene overexpression of the CSE and CBS in Drosophila induce similar effects on stress-resistance and locomotor activity, however lifespan extending effect was revealed for CBS overexpression only.

SIRT6 transcriptionally regulates global protein synthesis through transcription factor Sp1 independent of its deacetylase activity

Global protein synthesis is emerging as an important player in the context of aging and age-related diseases. However, the intricate molecular networks that regulate protein synthesis are poorly understood. Here, we report that SIRT6, a nuclear-localized histone deacetylase represses global protein synthesis by transcriptionally regulating mTOR signalling via the transcription factor Sp1, independent of its deacetylase activity. Our results suggest that SIRT6 deficiency increases protein synthesis in mice. Further, multiple lines of in vitro evidence suggest that SIRT6 negatively regulates protein synthesis in a cell-autonomous fashion and independent of its catalytic activity. Mechanistically, SIRT6 binds to the zinc finger DNA binding domain of Sp1 and represses its activity. SIRT6 deficiency increased the occupancy of Sp1 at key mTOR signalling gene promoters resulting in enhanced expression of these genes and activation of the mTOR signalling pathway. Interestingly, inhibition of either mTOR or Sp1 abrogated the increased protein synthesis observed under SIRT6 deficient conditions. Moreover, pharmacological inhibition of mTOR restored cardiac function in muscle-specific SIRT6 knockout mice, which spontaneously develop cardiac hypertrophy. Overall, these findings have unravelled a new layer of regulation of global protein synthesis by SIRT6, which can be potentially targeted to combat aging-associated diseases like cardiac hypertrophy.

SIRT6 Promotes Hepatic Beta-Oxidation via Activation of PPARα

The pro-longevity enzyme SIRT6 regulates various metabolic pathways. Gene expression analyses in SIRT6 heterozygotic mice identify significant decreases in PPARα signaling, known to regulate multiple metabolic pathways. SIRT6 binds PPARα and its response element within promoter regions and activates gene transcription. Sirt6+/- results in significantly reduced PPARα-induced β-oxidation and its metabolites and reduced alanine and lactate levels, while inducing pyruvate oxidation. Reciprocally, starved SIRT6 transgenic mice show increased pyruvate, acetylcarnitine, and glycerol levels and significantly induce β-oxidation genes in a PPARα-dependent manner. Furthermore, SIRT6 mediates PPARα inhibition of SREBP-dependent cholesterol and triglyceride synthesis. Mechanistically, SIRT6 binds PPARα coactivator NCOA2 and decreases liver NCOA2 K780 acetylation, which stimulates its activation of PPARα in a SIRT6-dependent manner. These coordinated SIRT6 activities lead to regulation of whole-body respiratory exchange ratio and liver fat content, revealing the interactions whereby SIRT6 synchronizes various metabolic pathways, and suggest a mechanism by which SIRT6 maintains healthy liver.

Current nutritional and pharmacological anti-aging interventions

Aging is the main risk factor for chronic diseases and disablement in human societies with a great impact in social and health care expenditures. So far, aging and, eventually, death are unavoidable. Nevertheless, research efforts on aging-associated diseases with the aim not only to extend life span but also to increment health span in an attempt to delay, stop and even reverse the aging process have not stopped growing. Caloric restriction extends both health and life span in several short-lived experimental models and has brought to light the role of different molecular effectors involved in nutrient sensing pathways and longevity. This opens the possibility of modulating these molecular effectors also in humans to increase longevity and health span. The difficulty to implement caloric restricted diets in humans has led to the development of new bearable diets such as time-restricted feeding, intermittent fasting or diets with limited amounts of some nutrients and to the search of pharmacological agents, targeted to the effectors that mediate the extension of life and health span in response to these anti-aging diets. Pharmacological approaches that eliminate senescent cells or prevent primary causes of aging such as telomere attrition also emerge as potential anti-aging strategies. In the present article, we review these possible nutritional and pharmacological interventions designed to mitigate and/or delay the aging process and to increase health and life span.

The conserved histone chaperone LIN-53 is required for normal lifespan and maintenance of muscle integrity in Caenorhabditis elegans

Whether extension of lifespan provides an extended time without health deteriorations is an important issue for human aging. However, to which degree lifespan and aspects of healthspan regulation might be linked is not well understood. Chromatin factors could be involved in linking both aging aspects, as epigenetic mechanisms bridge regulation of different biological processes. The epigenetic factor LIN‐53 (RBBP4/7) associates with different chromatin‐regulating complexes to safeguard cell identities in Caenorhabditis elegans as well as mammals, and has a role in preventing memory loss and premature aging in humans. We show that LIN‐53 interacts with the nucleosome remodeling and deacetylase (NuRD) complex in C. elegans muscles to ensure functional muscles during postembryonic development and in adults. While mutants for other NuRD members show a normal lifespan, animals lacking LIN‐53 die early because LIN‐53 depletion affects also the histone deacetylase complex Sin3, which is required for a normal lifespan. To determine why lin‐53 and sin‐3 mutants die early, we performed transcriptome and metabolomic analysis revealing that levels of the disaccharide trehalose are significantly decreased in both mutants. As trehalose is required for normal lifespan in C. elegans, lin‐53 and sin‐3 mutants could be rescued by either feeding with trehalose or increasing trehalose levels via the insulin/IGF1 signaling pathway. Overall, our findings suggest that LIN‐53 is required for maintaining lifespan and muscle integrity through discrete chromatin regulatory mechanisms. Since both LIN‐53 and its mammalian homologs safeguard cell identities, it is conceivable that its implication in lifespan regulation is also evolutionarily conserved.

Methods for studying human sirtuins with activity-based chemical probes

Sirtuins are unique posttranslational modification enzymes that utilize NAD⁺ as the co-substrate to remove acyl groups from lysine residues. The deacylation events result in profound biological consequences, from transcription silencing to metabolism regulation. This article focuses on a newly developed technology using activity-based chemical probes to report sirtuin functional state in various settings. These chemical probes, thioacyllysine peptides carrying photo-cross-linker as well as bioorthogonal functionality, target the active site of sirtuins to form stalled reaction intermediate. Subsequently, the probe forms covalent adduct with the protein through photocrosslinking. Ultimately, the active sirtuin can be visualized via "click" chemistry-mediated conjugation to a fluorescent tag. Here, we describe the labeling protocols on recombinant protein, whole cell lysate, and in situ labeling.

D-Allose, a Stereoisomer of D-Glucose, Extends the Lifespan of Caenorhabditis elegans via Sirtuin and Insulin Signaling

D-Allose (D-All), C-3 epimer of D-glucose, is a rare sugar known to suppress reactive oxygen species generation and prevent hypertension. We previously reported that D-allulose, a structural isomer of D-All, prolongs the lifespan of the nematode Caenorhabditis elegans. Thus, D-All was predicted to affect longevity. In this study, we provide the first empirical evidence that D-All extends the lifespan of C. elegans. Lifespan assays revealed that a lifespan extension was induced by 28 mM D-All. In particular, a lifespan extension of 23.8 % was achieved (p < 0.0001). We further revealed that the effects of D-All on lifespan were dependent on the insulin gene daf-16 and the longevity gene sir-2.1, indicating a distinct mechanism from those of other hexoses, such as D-allulose, with previously reported antiaging effects.

Antiaging effect of a Jianpi-yangwei formula in Caenorhabditis elegans

Background

Jianpi-yangwei (JPYW), a traditional Chinese medicine (TCM), helps to nourish the stomach and spleen and is primarily used to treat functional declines related to aging. This study aimed to explore the antiaging effects and mechanism of JPYW by employing a Caenorhabditis elegans model.

Methods

Wild-type C. elegans N2 worms were cultured in growth medium with or without JPYW, and lifespan analysis, oxidative and heat stress resistance assays, and other aging-related assays were performed. The effects of JPYW on the levels of superoxide dismutase (SOD) and the expression of specific genes were examined to explore the underlying mechanism of JPYW.

Results

Compared to control worms, JPYW-treated wild-type worms showed increased survival times under both normal and stress conditions (P < 0.05). JPYW-treated worms also exhibited enhanced reproduction, movement and growth and decreased intestinal lipofuscin accumulation compared to controls (P < 0.05). Furthermore, increased activity of SOD, downregulated expression levels of the proaging gene clk-2 and upregulated expression levels of the antiaging genes daf-16, skn-1, and sir-2.1 were observed in the JPYW group compared to the control group.

Conclusion

Our findings suggest that JPYW extends the lifespan of C. elegans and exerts antiaging effects by increasing the activity of an antioxidant enzyme (SOD) and by regulating the expression of aging-related genes. This study not only indicates that this Chinese compound exerts antiaging effects by activating and repressing target genes but also provides a proven methodology for studying the biological mechanisms of TCMs.

A fln-2 mutation affects lethal pathology and lifespan in C. elegans

Differences in genetic background in model organisms can have complex effects on phenotypes of interest. We previously reported a difference in hermaphrodite lifespan between two wild-type lines widely used by C. elegans researchers (N2 hermaphrodite and male stocks). Here, using pathology-based approaches and genome sequencing, we identify the cause of this difference as a nonsense mutation in the filamin gene fln-2 in the male stock, which reduces early mortality caused by pharyngeal infection. We show how fln-2 variation explains previous discrepancies involving effects of sir-2.1 (sirtuin deacetylase) on ageing, and show that in a fln-2(+) background, sir-2.1 over-expression causes an FUDR (DNA synthesis inhibitor)-dependent reduction in pharyngeal infection and increase in lifespan. In addition we show how fln-2 variation confounds effects on lifespan of daf-2 (insulin/IGF-1 signalling), daf-12 (steroid hormone signalling), and eat-2 (putative dietary restriction). These findings underscore the importance of identifying and controlling genetic background variation.

Neuronal Mechanisms that Drive Organismal Aging Through the Lens of Perception

Sensory neurons provide organisms with data about the world in which they live, for the purpose of successfully exploiting their environment. The consequences of sensory perception are not simply limited to decision-making behaviors; evidence suggests that sensory perception directly influences physiology and aging, a phenomenon that has been observed in animals across taxa. Therefore, understanding the neural mechanisms by which sensory input influences aging may uncover novel therapeutic targets for aging-related physiologies. In this review, we examine different perceptive experiences that have been most clearly linked to aging or age-related disease: food perception, social perception, time perception, and threat perception. For each, the sensory cues, receptors, and/or pathways that influence aging as well as the individual or groups of neurons involved, if known, are discussed. We conclude with general thoughts about the potential impact of this line of research on human health and aging.

Genetic Pathways of Aging and Their Relevance in the Dog as a Natural Model of Human Aging

Aging research has experienced a burst of scientific efforts in the last decades as the growing ratio of elderly people has begun to pose an increased burden on the healthcare and pension systems of developed countries. Although many breakthroughs have been reported in understanding the cellular mechanisms of aging, the intrinsic and extrinsic factors that contribute to senescence on higher biological levels are still barely understood. The dog, Canis familiaris, has already served as a valuable model of human physiology and disease. The possible role the dog could play in aging research is still an open question, although utilization of dogs may hold great promises as they naturally develop age-related cognitive decline, with behavioral and histological characteristics very similar to those of humans. In this regard, family dogs may possess unmatched potentials as models for investigations on the complex interactions between environmental, behavioral, and genetic factors that determine the course of aging. In this review, we summarize the known genetic pathways in aging and their relevance in dogs, putting emphasis on the yet barely described nature of certain aging pathways in canines. Reasons for highlighting the dog as a future aging and gerontology model are also discussed, ranging from its unique evolutionary path shared with humans, its social skills, and the fact that family dogs live together with their owners, and are being exposed to the same environmental effects.

Gastro-intestinal and oral microbiome signatures associated with healthy aging

The human oral and gut microbiomes influence health via competition for a distinct niche in the body with pathogens, via metabolic capabilities that increase host digestive capacity and generate compounds engaged in signaling pathways and modulation of immune system functions. Old age alters our metabolic and regenerative capacity. Following recruitment of 65 human subjects in the age range of 70 to 82, we discerned healthy aging (HA) and non-healthy aging (NHA) cohorts discordant in the occurrence of one or more major diseases: (1) cancer, (2) acute or chronic cardiovascular diseases, (3) acute or chronic pulmonary diseases, (4) diabetes, and (5) stroke or neurodegenerative disorders. We analyzed these cohorts' oral microbiomes (saliva) and gut microbiomes (stool) to assess diversity and identify microbial biomarkers for HA. In contrast to the gut microbiome where no change was observed, we found that the saliva microbiome had higher α-diversity in the HA compared with the NHA group. We observed the genus Akkermansia to be significantly more abundant in the gut microbiota of the HA group. Akkermansia muciniphila is a colonic mucin-degrading bacterium believed to have beneficial effects on gastrointestinal health, particularly in the context of diabetes and obesity. Erysipelotrichaceae UCG-003 was a taxon increased in abundance in the HA cohort. Streptococcus was the only genus observed to be significantly decreased in abundance in both the gut and oral microbiomes of the HA cohort compared with the NHA cohort. Our data support the notion that these microbes are potential probiotics to decrease the risks of non-healthy aging.

Sirtuin 1 alleviates endoplasmic reticulum stress-mediated apoptosis of intestinal epithelial cells in ulcerative colitis

BACKGROUND

Sirtuin 1 (SIRT1) is a nicotinamide adenine dinucleotide (NAD⁺)-dependent protein deacetylase that is involved in various diseases, including cancers, metabolic diseases, and inflammation-associated diseases. However, the role of SIRT1 in ulcerative colitis (UC) is still confusing.

AIM

To investigate the role of SIRT1 in intestinal epithelial cells (IECs) in UC and further explore the underlying mechanisms.

METHODS

We developed a coculture model using macrophages and Caco-2 cells. After treatment with the SIRT1 activator SRT1720 or inhibitor nicotinamide (NAM), the expression of occludin and zona occludens 1 (ZO-1) was assessed by Western blot analysis. Annexin V-APC/7-AAD assays were performed to evaluate Caco-2 apoptosis. Dextran sodium sulfate (DSS)-induced colitis mice were exposed to SRT1720 or NAM for 7 d. Transferase-mediated dUTP nick-end labeling (TUNEL) assays were conducted to assess apoptosis in colon tissues. The expression levels of glucose-regulated protein 78 (GRP78), CCAAT/enhancer-binding protein homologous protein (CHOP), caspase-12, caspase-9, and caspase-3 in Caco-2 cells and the colon tissues of treated mice were examined by quantitative real-time PCR and Western blot.

RESULTS

SRT1720 treatment increased the protein levels of occludin and ZO-1 and inhibited Caco-2 apoptosis, whereas NAM administration caused the opposite effects. DSS-induced colitis mice treated with SRT1720 had a lower disease activity index (P < 0.01), histological score (P < 0.001), inflammatory cytokine levels (P < 0.01), and apoptotic cell rate (P < 0.01), while exposure to NAM caused the opposite effects. Moreover, SIRT1 activation reduced the expression levels of GRP78, CHOP, cleaved caspase-12, cleaved caspase-9, and cleaved caspase-3 in Caco-2 cells and the colon tissues of treated mice.

CONCLUSION

SIRT1 activation reduces apoptosis of IECs via the suppression of endoplasmic reticulum stress-mediated apoptosis-associated molecules CHOP and caspase-12. SIRT1 activation may be a potential therapeutic strategy for UC.

Resveratrol inhibited LPS induced transcription of immune genes and secretion of eicosanoids in Atlantic salmon (Salmo salar), comparing mono-, co- and a novel triple cell culture model of head kidney leukocytes, liver cells and visceral adipocyte tissue

The aim was to study the effect of resveratrol on the interplay of inflammatory signals using three different cell models; a metabolic organ (liver), an endocrine organ (visceral adipose tissue, VAT) and an immune organ (head kidney leukocytes, HKL) following lipopolysaccharide challenge (LPS). Atlantic salmon HKL, liver cells and VAT were isolated from the same fish (n = 5). Each cell type was cultured either as mono-cultures, as co-cultures between HKL-liver cells, liver cells-VAT and HKL-VAT. Triple -cultures included all three tissues. In all cultures of HKL, LPS induced transcription of IL-1β, cox2, tnfα, IL-12, ccattβ and Ahr were significantly inhibited by resveratrol (100, 200 μM). Likewise, in all cultures of liver cells, the LPS induced expression of IL-1β was inhibited by resveratrol (100 and 200 μM). HKL, both mono-cultures and triple-cultures and VAT cocultured with liver cells, showed LPS induced cox2 transcription that was inhibited by resveratrol (100 and 200 μM). In contrast, VAT cultured as triple cultures, resveratrol 200 μM particularly, in the presence of LPS, seemed to increase the expression of IL-1β and ccattβ. Resveratrol did not significantly affect lox5 expression in any culture. HKL and VAT are the main producers of PGE2 in response to inflammatory stimuli. VAT showed high endogenous production of eicosanoids, particularly LTB4 and LTB5. Resveratrol inhibited bot LPS induced and endogenous eicosanoid production. Possible targets of resveratrol, Sirt1 and pAMPK were affected differently in the different cells and tissue studied.

Early-onset aging and mitochondrial defects associated with loss of histone acetyltransferase 1 (Hat1)

Histone acetyltransferase 1 (Hat1) is responsible for the acetylation of newly synthesized histone H4 on lysines 5 and 12 during the process of chromatin assembly. To understand the broader biological role of Hat1, we have generated a conditional mouse knockout model of this enzyme. We previously reported that Hat1 is required for viability and important for mammalian development and genome stability. In this study, we show that haploinsufficiency of Hat1 results in a significant decrease in lifespan. Defects observed in Hat1^+/− mice are consistent with an early‐onset aging phenotype. These include lordokyphosis (hunchback), muscle atrophy, minor growth retardation, reduced subcutaneous fat, cancer, and paralysis. In addition, the expression of Hat1 is linked to the normal aging process as Hat1 mRNA and protein becomes undetectable in many tissues in old mice. At the cellular level, fibroblasts from Hat1 haploinsufficient embryos undergo early senescence and accumulate high levels of p21. Hat1^+/− mouse embryonic fibroblasts (MEFs) display modest increases in endogenous DNA damage but have significantly higher levels of reactive oxygen species (ROS). Consistently, further studies show that Hat1^−/− MEFs exhibit mitochondrial defects suggesting a critical role for Hat1 in mitochondrial function. Taken together, these data show that loss of Hat1 induces multiple hallmarks of early‐onset aging.

Effects of Lycium barbarum Polysaccharides on Health and Aging of C. elegans Depend on daf-12/daf-16

As the global population ages, searching for drugs and functional foods which can slow down the aging process has attracted a number of researchers. In this paper, the Lycium barbarum polysaccharides (LBP) extracted from Lycium barbarum was characterized and the effects of LBP on the aging and health of C. elegans were studied. Results showed that LBP can prolong the lifespan, improve the abilities to withstand environmental stress, enhance reproductive potentials, and maintain muscle integrity of C. elegans. By using genetically mutated C. elegans strains, RNAi gene silencing, and measuring the mRNA expression level, it was demonstrated that the lifespan of C. elegans was extended by LBP mainly through sir-2.1, daf-12, and daf-16. The present study might provide a basis for further study of LBP as a food or drug to interfere with aging and reduce the incidence of age-related diseases.

Maximizing Longevity and Healthspan: Multiple Approaches All Converging on Autophagy

Our understanding of the molecular basis of aging has greatly increased over the past few decades. In this review, we provide an overview of the key signaling pathways associated with aging, and whose modulation has been shown to extend lifespan in a range of model organisms. We also describe how these pathways converge onto autophagy, a catabolic process that functions to recycle dysfunctional cellular material and maintains energy homeostasis. Finally, we consider various approaches of therapeutically modulating these longevity pathways, highlighting exercise as a potent geroprotector.

The Microbiome and Aging

Aging is a natural process of organismal decay that underpins the development of myriad diseases and disorders. Extensive efforts have been made to understand the biology of aging and its regulation, but most studies focus solely on the host organism. Considering the pivotal role of the microbiota in host health and metabolism, we propose viewing the host and its microbiota as a single biological entity whose aging phenotype is influenced by the complex interplay between host and bacterial genetics. In this review we present how the microbiota changes as the host ages, but also how the intricate relationship between host and indigenous bacteria impacts organismal aging and life span. In addition, we highlight other microbiota-dependent mechanisms that potentially regulate aging, and present experimental animal models for addressing these questions. Importantly, we propose microbiome dysbiosis as an additional hallmark and biomarker of aging.

Identification and Application of Gene Expression Signatures Associated with Lifespan Extension

Several pharmacological, dietary, and genetic interventions that increase mammalian lifespan are known, but general principles of lifespan extension remain unclear. Here, we performed RNA sequencing (RNA-seq) analyses of mice subjected to 8 longevity interventions. We discovered a feminizing effect associated with growth hormone regulation and diminution of sex-related differences. Expanding this analysis to 17 interventions with public data, we observed that many interventions induced similar gene expression changes. We identified hepatic gene signatures associated with lifespan extension across interventions, including upregulation of oxidative phosphorylation and drug metabolism, and showed that perturbed pathways may be shared across tissues. We further applied the discovered longevity signatures to identify new lifespan-extending candidates, such as chronic hypoxia, KU-0063794, and ascorbyl-palmitate. Finally, we developed GENtervention, an app that visualizes associations between gene expression changes and longevity. Overall, this study describes general and specific transcriptomic programs of lifespan extension in mice and provides tools to discover new interventions.

The sirtuin family in cancer

Sirtuins are a family of protein deacylases and ADP-ribosyl-transferases, homologs to the yeast SIR2 protein. Seven sirtuin paralogs have been described in mammals, with different subcellular locations, targets, enzymatic activities, and regulatory mechanisms. All sirtuins share NAD+ as substrate, placing them as central metabolic hubs with strong relevance in lifespan, metabolism, and cancer development. Much effort has been devoted to studying the roles of sirtuins in cancer, providing a wealth of data on sirtuins roles in mouse models and humans. Also, extensive data are available on the effects of pharmacological modulation of sirtuins in cancer development. Here, we present a comprehensive and organized resume of all the existing evidence linking every sirtuin with cancer development. From our analysis, we conclude that sirtuin modulation after tumor initiation results in unpredictable outcomes in most tumor types. On the contrary, all genetic and pharmacological models indicate that sirtuins activation prior to tumor initiation can constitute a powerful preventive strategy.

SIRT6, a Mammalian Deacylase with Multitasking Abilities

Mammalian sirtuins have emerged in recent years as critical modulators of multiple biological processes, regulating cellular metabolism, DNA repair, gene expression, and mitochondrial biology. As such, they evolved to play key roles in organismal homeostasis, and defects in these proteins have been linked to a plethora of diseases, including cancer, neurodegeneration, and aging. In this review, we describe the multiple roles of SIRT6, a chromatin deacylase with unique and important functions in maintaining cellular homeostasis. We attempt to provide a framework for such different functions, for the ability of SIRT6 to interconnect chromatin dynamics with metabolism and DNA repair, and the open questions the field will face in the future, particularly in the context of putative therapeutic opportunities.

Metabolic regulation of lifespan from a C. elegans perspective

Decline of cellular functions especially cognitive is a major deficit that arises with age in humans. Harnessing the strengths of small and genetic tractable model systems has revealed key conserved regulatory biochemical and signaling pathways that control aging. Here, we review some of the key signaling and biochemical pathways that coordinate aging processes with special emphasis on Caenorhabditis elegans as a model system and discuss how nutrients and metabolites can regulate lifespan by coordinating signaling and epigenetic programs. We focus on central nutrient-sensing pathways such as mTOR and insulin/insulin-like growth factor signaling and key transcription factors including the conserved basic helix-loop-helix transcription factor HLH-30/TFEB.

Deacetylation of metabolic enzymes by Sirt2 modulates pyruvate homeostasis to extend insect lifespan

Diapause in insects is akin to dauer in Caenorhabditis elegans and hibernation in vertebrates. Diapause causes a profound extension of lifespan by low metabolic activity. However, the detailed regulatory mechanisms for low metabolic activity remain unknown. Here, we showed that low pyruvate levels are present in the brains of diapause-destined pupae of the cotton bollworm Helicoverpa armigera, and three enzymes pyruvate kinase (PK), phosphoenolpyruvate carboxykinase (PEPCK), and phosphoglycerate mutase (PGAM) are closely correlated with pyruvate homeostasis. Notably, Sirt2 can deacetylate the three enzymes to increase their activity in vitro. Thus, low Sirt2 expression in the brains of diapause individuals decreases PK and PEPCK protein levels as well as PGAM activity, resulting in low pyruvate levels and low tricarboxylic acid cycle activity and eventually inducing diapause initiation by low metabolic activity. These findings suggest that pyruvate is a checkpoint for development or lifespan extension, and Sirt2 is a negative regulator to extend lifespan in insects.

Sirtuins as regulators of the cellular stress response and metabolism in marine ectotherms

The effects of climate change are altering the environmental landscape of marine habitats and exposing organisms to stressful conditions that may exceed their tolerance limits. Marine intertidal organisms are well adapted to fluctuating environments by adjusting energy metabolism and inducing the cellular stress response (CSR). Recent studies have shown that food availability can influence stress tolerance of marine ectotherms where a well-fed organism is more "robust" and more likely to survive a stressor than an animal under a low-food regime. We propose that the link between food availability and stress tolerance in marine ectotherms may be regulated by sirtuins, NAD⁺-dependent deacylases. In model organisms sirtuins act as energy sensors and are active under calorie restricted states where they target and regulate cellular metabolism, minimize oxidative stress, and influence the CSR. However, we know little regarding sirtuins in marine ectotherms. Herein we review the current literature on sirtuins in marine ectotherms including marine teleosts, limpets, and mussels. We show that the role of sirtuins in marine ectotherms is conserved from model organisms in regulating the CSR and energy, but the direct connection to NAD⁺ status under fed and starved conditions requires more attention. Although there is a beginning foundation of research regarding sirtuins in marine organisms, it is limited and would benefit from targeted studies investigating sirtuin activity in various tissues and animals under multiple stressors, NAD⁺/NADH levels under various fed states, and by using known sirtuin inhibitors and activators to elucidate the potential targets of sirtuins in marine animals.

Resveratrol and HIV-protease inhibitors control UCP1 expression through opposite effects on p38 MAPK phosphorylation in human adipocytes

Brown and brown-like adipocytes (BBAs) control thermogenesis and are detected in adult humans. They express UCP1, which transforms energy into heat. They appear as promising cells to fight obesity. Deciphering the molecular mechanisms leading to the browning of human white adipocytes or the whitening of BBAs represents a goal to properly and safely control the pathways involved in these processes. Here, we analyzed how drugs endowed with therapeutic potential affect the differentiation of human adipose progenitor-cells into BBAs and/or their phenotype. We showed that HIV-protease inhibitors (PI) reduced UCP1 expression in BBAs modifying their metabolic profile and the mitochondria functionality. Lopinavir (LPV) was more potent than darunavir (DRV), a last PI generation. PPARγ and PGC-1α were decreased in a PI or cell-specific manner, thus altering UCP1's constitutive expression. In addition, LPV altered p38 MAPK phosphorylation, blunting then the β-adrenergic responses. In contrast, low doses of resveratrol stimulated the activatable expression of UCP1 in a p38 MAPK-dependent manner and counteracted the LPV induced loss of UCP1. This effect was independent of the resveratrol-induced sirtuin-1 expression. Altogether our results uncover how drugs impact crucial components of the networks regulating the expression of the thermogenic signature. They provide important information to control the relevant pathways involved in energy expenditure.

Longevity: Lesson from Model Organisms

Research on longevity and healthy aging promises to increase our lifespan and decrease the burden of degenerative diseases with important social and economic effects. Many aging theories have been proposed, and important aging pathways have been discovered. Model organisms have had a crucial role in this process because of their short lifespan, cheap maintenance, and manipulation possibilities. Yeasts, worms, fruit flies, or mammalian models such as mice, monkeys, and recently, dogs, have helped shed light on aging processes. Genes and molecular mechanisms that were found to be critical in simple eukaryotic cells and species have been confirmed in humans mainly by the functional analysis of mammalian orthologues. Here, we review conserved aging mechanisms discovered in different model systems that are implicated in human longevity as well and that could be the target of anti-aging interventions in human.

The complete genome sequence of Bifidobacterium longum LTBL16, a potential probiotic strain from healthy centenarians with strong antioxidant activity

B. longum LTBL16 is a potential probiotic strain that was isolated from healthy centenarians in Bama, China. In vitro experiments show that B. longum LTBL16 has a strong antioxidant activity and the complete genome of B. longum LTBL16 was sequenced in this work. The genome consists of one 2,430,682 bp circular chromosome that is plasmid free. The circular chromosome has a GC content of 61.23% and contains 2071 coding sequences (CDSs), 4 rRNA manipulators and 55 tRNA coding genes. Genetic analysis showed that at least five protein-coding genes were associated with antioxidant activity, and the abundance of these genes may be related to free radical scavenging rates and oxygen tolerance. In addition, the safety of B. longum LTBL16 was evaluated using a virulence factor database and antibiotic resistance gene database. The results indicate that B. longum LTBL16 has the good potential for the development and utilization as a probiotic.

Molecular docking analysis of imine stilbene analogs and evaluation of their anti-aging activity using yeast and mammalian cell models

The NAD⁺-dependent histone deacetylase SIRT1 was shown to be associated with aging and longevity. A stilbene, resveratrol (RV) was shown to exert anti-aging activity by stimulating the SIRT1 activity. However, the utility of RV is limited by its low bioavailability and structural instability. It is thus envisaged to test imine stilbene (IMS) analogs of RV for their potential anti-aging activity. In the present study, molecular docking analysis of five IMS analogs (3a, 3b, 3c, 3d and 3e) against the SIRT1 protein has been carried out. All the five IMS analogs displayed enhanced binding affinity towards SIRT1; three out of five IMS analogs (3a, 3 b, 3e) showed significantly higher affinity with lower binding energies (-9.58, -9.54, and -9.82 kcal mol^-1) than RV (-8.11 kcal mol^-1). Further, experimental validation of anti-aging activity was performed by measuring the chronological life span in vitro using yeast and cellular replicative senescence (CRS) in mammalian cell line models. All IMS analogs extended the chronological life span in yeast as compared to untreated cells as well as RV treated cells. Enhanced anti-aging activity was also observed in an analogous mammalian cell line model upon treatment with either RV or IMS analogs. The results thus suggest that most of the IMS analogs tested may serve as potent drug lead molecules with anti-aging activity.

Spatio-temporal expression profile of sirtuins during aging of the annual fish Nothobranchius furzeri

The founding member of the sirtuin family, yeast Sir2, was the first evolutionarily conserved gene to be identified as a regulator of longevity. Sirtuins constitute a protein family of metabolic sensors, translating changes in NAD + levels into adaptive responses, thereby acting as crucial regulators of the network that controls energy homeostasis and as such determines healthspan. In mammals the sirtuin family comprises seven proteins, SIRT1-SIRT7, which vary in tissue specificity, subcellular localization, enzymatic activity and targets. Here, we report the identification and a detailed spatio-temporal expression profile of sirtuin genes in the short-lived fish Nothobranchius furzeri, from embryogenesis to late adulthood, mapping its entire life cycle. Database exploration of the recently published N. furzeri genome revealed eight orthologues corresponding to the seven known mammalian sirtuins, including two copies of the sirt5 gene. Phylogenetic analysis showed high cross species similarity of individual sirtuins in both their overall amino acid sequence and catalytic domain, suggesting a high degree of functional conservation. Moreover, we show that N. furzeri sirtuins exhibit ubiquitous and wide tissue distribution with a unique spatial expression pattern for each individual member of this enzyme family. Specifically, we observed a transcriptional down-regulation of several sirtuin genes with age, most significantly sirt1, sirt5a, sirt6 and sirt7 in a wide range of functionally distinct tissues. Overall, this spatio-temporal expression analysis provides the foundation for future research, both into genetic and pharmacological manipulation of this important group of enzymes in Nothobranchius furzeri, an emerging model organism for aging research.

SIRT1: a potential tumour biomarker and therapeutic target

SIRT1, which is highly homologous to yeast silent information regulator 2, has recently garnered tremendous attention because of its various regulatory effects in several pathological conditions. Numerous studies have found that SIRT1 is highly expressed in a broad range of tumours compared with the paracancerous tissue. However, the role of SIRT1 in malignancies has yet to be systematically elucidated, and its use as a promising biomarker or therapeutic target for tumours has not been well-reported. Herein, we focus on the roles of SIRT1 in cancers and summarise the potential use of SIRT1 as a promising tumour biomarker or therapeutic target.

Sirtuin signaling in cellular senescence and aging

Sirtuin is an essential factor that delays cellular senescence and extends the organismal lifespan through the regulation of diverse cellular processes. Suppression of cellular senescence by Sirtuin is mainly mediated through delaying the age-related telomere attrition, sustaining genome integrity and promotion of DNA damage repair. In addition, Sirtuin modulates the organismal lifespan by interacting with several lifespan regulating signaling pathways including insulin/IGF-1 signaling pathway, AMP-activated protein kinase, and forkhead box O. Although still controversial, it is suggested that the prolongevity effect of Sirtuin is dependent with the level of and with the tissue expression of Sirtuin. Since Sirtuin is also believed to mediate the prolongevity effect of calorie restriction, activators of Sirtuin have attracted the attention of researchers to develop therapeutics for age-related diseases. Resveratrol, a phytochemical rich in the skin of red grapes and wine, has been actively investigated to activate Sirtuin activity with consequent beneficial effects on aging. This article reviews the evidences and controversies regarding the roles of Sirtuin on cellular senescence and lifespan extension, and summarizes the activators of Sirtuin including Sirtuin-activating compounds and compounds that increase the cellular level of nicotinamide dinucleotide.

Inhibition of GIP signaling extends lifespan without caloric restriction

AIMS/INTRODUCTION

Caloric restriction (CR) promotes longevity and exerts anti-aging effects by increasing Sirtuin production and activation. Gastric inhibitory polypeptide (GIP), a gastrointestinal peptide hormone, exerts various effects on pancreatic β-cells and extra-pancreatic tissues. GIP promotes glucose-dependent augmentation of insulin secretion and uptake of nutrients into the adipose tissue.

MATERIALS AND METHODS

Gipr^-/- and Gipr^+/+ mice were used for lifespan analysis, behavior experiments and gene expression of adipose tissue and muscles. 3T3-L1 differentiated adipocytes were used for Sirt1 and Nampt expression followed by treatment with GIP and α-lipoic acid.

RESULTS

We observed that GIP receptor-knockout (Gipr^-/-) mice fed normal diet showed an extended lifespan, increased exploratory and decreased anxiety-based behaviors, which are characteristic behavioral changes under CR. Moreover, Gipr^-/- mice showed increased Sirt1 and Nampt expression in the adipose tissue. GIP suppressed α-lipoic acid-induced Sirt1 expression and activity in differentiated adipocytes.

CONCLUSIONS

Although maintenance of CR is difficult, food intake and muscle endurance of Gipr^-/- mice were similar to those of wild-type mice. Inhibition of GIP signaling may be a novel strategy to extend the lifespan of diabetic patients.

Chasing the FOXO3: Insights into Its New Mitochondrial Lair in Colorectal Cancer Landscape

Colorectal cancer (CRC) poses a formidable challenge in terms of molecular heterogeneity, as it involves a variety of cancer-related pathways and molecular changes unique to an individual’s tumor. On the other hand, recent advances in DNA sequencing technologies provide an unprecedented capacity to comprehensively identify the genetic alterations resulting in tumorigenesis, raising the hope that new therapeutic approaches based on molecularly targeted drugs may prevent the occurrence of chemoresistance. Regulation of the transcription factor FOXO3a in response to extracellular cues plays a fundamental role in cellular homeostasis, being part of the molecular machinery that drives cells towards survival or death. Indeed, FOXO3a is controlled by a range of external stimuli, which not only influence its transcriptional activity, but also affect its subcellular localization. These regulation mechanisms are mediated by cancer-related signaling pathways that eventually drive changes in FOXO3a post-translational modifications (e.g., phosphorylation). Recent results showed that FOXO3a is imported into the mitochondria in tumor cells and tissues subjected to metabolic stress and cancer therapeutics, where it induces expression of the mitochondrial genome to support mitochondrial metabolism and cell survival. The current review discusses the potential clinical relevance of multidrug therapies that drive cancer cell fate by regulating critical pathways converging on FOXO3a.

Histone Modifications as an Intersection Between Diet and Longevity

Histone modifications are key epigenetic regulators that control chromatin structure and gene transcription, thereby impacting on various important cellular phenotypes. Over the past decade, a growing number of studies have indicated that changes in various histone modifications have a significant influence on the aging process. Furthermore, it has been revealed that the abundance and localization of histone modifications are responsive to various environmental stimuli, such as diet, which can also affect gene expression and lifespan. This supports the notion that histone modifications can serve as a main cellular platform for signal integration. Hence, in this review we focus on the role of histone modifications during aging, report the data indicating that diet affects histone modification levels and explore the idea that histone modifications may function as an intersection through which diet regulates lifespan. A greater understanding of the epigenetic mechanisms that link environmental signals to longevity may provide new strategies for therapeutic intervention in age-related diseases and for promoting healthy aging.

Caloric Restriction Mimetics against Age-Associated Disease: Targets, Mechanisms, and Therapeutic Potential

The increase in life expectancy has boosted the incidence of age-related pathologies beyond social and economic sustainability. Consequently, there is an urgent need for interventions that revert or at least prevent the pathogenic age-associated deterioration. The permanent or periodic reduction of calorie intake without malnutrition (caloric restriction and fasting) is the only strategy that reliably extends healthspan in mammals including non-human primates. However, the strict and life-long compliance with these regimens is difficult, which has promoted the emergence of caloric restriction mimetics (CRMs). We define CRMs as compounds that ignite the protective pathways of caloric restriction by promoting autophagy, a cytoplasmic recycling mechanism, via a reduction in protein acetylation. Here, we describe the current knowledge on molecular, cellular, and organismal effects of known and putative CRMs in mice and humans. We anticipate that CRMs will become part of the pharmacological armamentarium against aging and age-related cardiovascular, neurodegenerative, and malignant diseases.

NAD+Metabolism in Aging and Cancer

Aging is a major risk factor for many types of cancer, and the molecular mechanisms implicated in aging, progeria syndromes, and cancer pathogenesis display considerable similarities. Maintaining redox homeostasis, efficient signal transduction, and mitochondrial metabolism is essential for genome integrity and for preventing progression to cellular senescence or tumorigenesis. NAD+is a central signaling molecule involved in these and other cellular processes implicated in age-related diseases and cancer. Growing evidence implicates NAD+decline as a major feature of accelerated aging progeria syndromes and normal aging. Administration of NAD+precursors such as nicotinamide riboside (NR) and nicotinamide mononucleotide (NMN) offer promising therapeutic strategies to improve health, progeria comorbidities, and cancer therapies. This review summarizes insights from the study of aging and progeria syndromes and discusses the implications and therapeutic potential of the underlying molecular mechanisms involved in aging and how they may contribute to tumorigenesis.

Hydrogen sulfide modulates SIRT1 and suppresses oxidative stress in diabetic nephropathy

DN is recognized as not only a leading cause of end stage renal disease (ESRD) but also an independent risk factor for cardiovascular disease (CVD). Novel therapeutic approaches to diabetic nephropathy (DN) are needed, or else, healthcare resources will be overwhelmed by the expected worldwide increase in associated cases of ESRD and CVD. Reactive oxygen species (ROS) and advanced glycation end product (AGE) are implicated in the development of DN. Hydrogen sulfide (H₂S) is known for its antioxidant and antiapoptotic characteristics. Simultaneously diabetics have lower H₂S levels. Thus, it is worth investigating the use of H₂S in treatment of DN. To investigate the potential therapeutic role of H₂S in DN. Sixty male rats were divided into four groups: control, DN, DN+NaHS30 µmol/kg/day and DN+NaHS100 µmol/kg/day. Fasting blood sugar (FBS), kidney function tests, SIRT1 activity, superoxide dismutase activity (SOD), malondialdehyde (MDA) and expression of caspase3 and p53 in renal tissues were assessed. Kidney was examined histopathologically. DN rats had higher FBS, renal dysfunction, decreased SIRT1 and SOD activity levels, increased caspase3 and p53 relative expression and increased MDA in renal tissues. NaHS increased SIRT1 and reversed biochemical, apoptotic, oxidant and pathologic parameters characteristic of DN, with better results using a dose of 100 µmol/kg/day. H₂S has a protective role against DN through decreasing FBS, ROS, apoptosis and upregulating SIRT1, thus preserving renal cells from further damage caused by DM.

MPK-1/ERK is required for the full activity of resveratrol in extended lifespan and reproduction

Resveratrol (RSV) extends the lifespan of various organisms through activation of sirtuin. However, whether RSV-mediated longevity is entirely dependent upon sirtuin is still controversial. Thus, understanding additional mechanisms concerning the genetic requirements for the biological activity of RSV needs to be clarified to utilize the beneficial effects of RSV. In this study using Caenorhabditis elegans as a model system, we found that MPK-1 (an ERK homolog) signaling is necessarily required for RSV-mediated longevity of sir-2.1/sirtuin mutants as well as for wild-type worms. We demonstrated that MPK-1 contributes to RSV-mediated longevity through nuclear accumulation of SKN-1 in a SIR-2.1/DAF-16 pathway-independent manner. The positive effect of RSV in regulating lifespan was completely abolished by RNA interference against mpk-1 in the sir-2.1 and daf-16 mutants, strongly indicating that the MPK-1/SKN-1 pathway is involved in RSV-mediated longevity, independently of SIR-2.1/DAF-16. We additionally found that RSV protected worms from oxidative stress via MPK-1. In addition to organismal aging, RSV prevented the age-associated loss of mitotic germ cells, brood size, and reproductive span through MPK-1 in C. elegans germline. Therefore, our findings not only provide new mechanistic insight into the controversial effects of RSV on organismal longevity, but additionally have important implications in utilizing RSV to improve the outcome of aging-related diseases.

Epigenetic Regulation of Bone Marrow Stem Cell Aging: Revealing Epigenetic Signatures associated with Hematopoietic and Mesenchymal Stem Cell Aging

In this review we explore the importance of epigenetics as a contributing factor for aging adult stem cells. We summarize the latest findings of epigenetic factors deregulated as adult stem cells age and the consequence on stem cell self-renewal and differentiation, with a focus on adult stem cells in the bone marrow. With the latest whole genome bisulphite sequencing and chromatin immunoprecipitations we are able to decipher an emerging pattern common for adult stem cells in the bone marrow niche and how this might correlate to epigenetic enzymes deregulated during aging. We begin by briefly discussing the initial observations in yeast, drosophila and Caenorhabditis elegans (C. elegans) that led to the breakthrough research that identified the role of epigenetic changes associated with lifespan and aging. We then focus on adult stem cells, specifically in the bone marrow, which lends strong support for the deregulation of DNA methyltransferases, histone deacetylases, acetylates, methyltransferases and demethylases in aging stem cells, and how their corresponding epigenetic modifications influence gene expression and the aging phenotype. Given the reversible nature of epigenetic modifications we envisage “epi” targeted therapy as a means to reprogram aged stem cells into their younger counterparts.

3-Methyl-3-buten-1-ol (isoprenol) confers longevity and stress tolerance in Caenorhabditis elegans

The present investigation demonstrates the longevity-promoting effects of 3-methyl-3-buten-1-ol (isoprenol) in the animal model Caenorhabditis elegans that might be served as a lead nutraceutical in geriatric research. Our results showed that 0.5 mM isoprenol extended the mean lifespan of worms by 25% in comparison to control worms. Isoprenol also significantly enhanced survival of the worms under various stress conditions. It was found that the longevity-promoting effects of isoprenol were associated with improved age-associated physiological behaviour and reduced intracellular reactive oxygen species (ROS) accumulation. Finally, studies with gene-specific mutants revealed the involvement of pro-longevity transcription factors (TFs) DAF-16 and SKN-1 with simultaneous over-expression of GST-4 and SOD-3 in isoprenol treated worms. In silico analysis revealed the binding affinity of isoprenol with DAF-16 and SKN-1 TFs. Together, the findings suggest that isoprenol is able to enhance the lifespan of C. elegans and embarks its potential in the developments of formulations for age-related ailments.

Regulatory Effects of NAD+ Metabolic Pathways on Sirtuin Activity

NAD⁺ acts as a crucial regulator of cell physiology and as an integral participant in cellular metabolism. By virtue of a variety of signaling activities this central metabolite can exert profound effects on organism health status. Thus, while it serves as a well-known metabolic cofactor functioning as a redox-active substrate, it can also function as a substrate for signaling enzymes, such as sirtuins, poly (ADP-ribosyl) polymerases, mono (ADP-ribosyl) transferases, and CD38. Sirtuins function as NAD⁺-dependent protein deacetylases (deacylases) and catalyze the reaction of NAD⁺ with acyllysine groups to remove the acyl modification from substrate proteins. This deacetylation provides a regulatory function and integrates cellular NAD⁺ metabolism into a large spectrum of cellular processes and outcomes, such as cell metabolism, cell survival, cell cycle, apoptosis, DNA repair, mitochondrial homeostasis and mitochondrial biogenesis, and even lifespan. Increased attention to how regulated and pharmacologic changes in NAD⁺ concentrations can impact sirtuin activities has motivated openings of new areas of research, including investigations of how NAD⁺ levels are regulated at the subcellular level, and searches for more potent NAD⁺ precursors typified by nicotinamide riboside (NR) and nicotinamide mononucleotide (NMN). This review describes current results and thinking of how NAD⁺ metabolic pathways regulate sirtuin activities and how regulated NAD⁺ levels can impact cell physiology. In addition, NAD⁺ precursors are discussed, with attention to how these might be harnessed to generate novel therapeutic options to treat the diseases of aging.