The controversial links among calorie restriction, SIRT1, and resveratrol

Malnutrition Risk in Older Adults: Evaluating the Diagnostic Relevance of Serum Biomarkers: SIRT-1, CCK-8, Melatonin, and Total Antioxidant Capacity (TAC)

Background/Objectives: Addressing the risk of malnutrition at an early stage is crucial to preventing its development, which can have a detrimental impact on physical and mental health status. This study investigates the potential role of biochemical biomarkers such as sirtuin 1 (SIRT-1), melatonin, cholecystokinin-8 (CCK-8), and total antioxidant capacity (TAC) in identifying the risk of malnutrition. Methods: This cross-sectional study assessed malnutrition risk in 153 community-dwelling older adults using the Mini Nutritional Assessment (MNA). Serum levels of SIRT-1, melatonin, and CCK-8 were analyzed with enzyme-linked immunosorbent assay (ELISA), and total antioxidant capacity (TAC) was measured using the ferric reducing ability of plasma (FRAP) method. Results: Serum levels of TAC and CCK-8 were significantly positively correlated with grip strength and visceral adipose tissue, with TAC levels also showing associations with appendicular skeletal muscle mass index (ASMI), total body water, total energy expenditure, fat-free mass index, and fat mass index (p < 0.001). CCK-8 emerged as a strong predictor of malnutrition risk (AUC = 0.58 in females, AUC = 0.64 in males), whereas SIRT-1 (AUC = 0.57 for both sexes), melatonin (AUC = 0.46 for females, AUC = 0.51 for males), and TAC (AUC = 0.42 for females, AUC = 0.54 for males) exhibited weaker predictive abilities. A multivariate model incorporating CCK-8 demonstrated excellent predictive accuracy (AUC = 0.84, 95% CI: 0.77-0.90) and indicated a potential association between elevated CCK-8 levels and a higher risk of malnutrition. Conclusions: In conclusion, this study highlights the effectiveness of a multi-parameter model incorporating CCK-8 as a reliable approach for assessing malnutrition risk in older adults, offering a comprehensive evaluation of the condition. However, further research is needed to confirm its applicability and accuracy in diverse elderly populations and clinical settings.

C-Terminal Binding Protein 2 Emerges as a Critical Player Linking Metabolic Imbalance to the Pathogenesis of Obesity

Metabolism is one of the vital functions of cells and living organisms, and the systems to sense and respond to the metabolic alterations play pivotal roles in a plethora of biological processes, including cell proliferative activities, immune cell functions, aging processes, and neuronal functions. Recently, we have reported that a transcriptional cofactor, C-terminal binding protein 2 (CtBP2), serves as a critical metabolite sensor in this context. CtBP2 has a structural pocket called Rossmann fold to accommodate metabolites, and it has been reported to be activated upon binding to NADH/NAD＋. Owing to its preferential binding affinity for NADH compared with NAD＋, increased glycolysis activates CtBP2 by regenerating NADH from NAD＋. Furthermore, we recently reported that fatty acyl-CoAs, metabolites accumulated under the condition of lipid overload, as represented by obesity, can inactivate CtBP2. These observations suggest that CtBP2 monitors not only redox state but also energy substrate preference in the maintenance of metabolic homeostasis. In line with these metabolite-sensing capabilities, CtBP2 is activated in healthy subjects to protect against metabolic disturbances, whereas inactivation of CtBP2 in obesity contributes to the pathogeneses of obesity.This metabolic system orchestrated by CtBP2 can provide a novel framework for understanding how cells maintain their homeostasis through coordination of metabolism, and CtBP2 incapacitation can be a critical point of the obesogenic cascade.

In Vitro Antioxidant and Fibroblast Migration Activities of Fractions Eluded from Dichloromethane Leaf Extract of Marantodes pumilum

(1) The complexity of diabetes and diabetic wound healing remains a therapeutic challenge because proper and systematic wound care and management are essential to prevent chronic microbial infection and mechanical damage to the skin. Marantodes pumilum, locally known as 'Kacip Fatimah', is an herb that has been previously reported to possess anti-inflammatory, analgesic, antinociceptive and antipyretic properties. The current study aims to assess the antioxidant and fibroblast cell migration activities of the fractions eluded from the dichloromethane extract of M. pumilum leaves. (2) The total antioxidant capacity of M. pumilum was assessed using the total proanthocyanidins and phosphomolybdenum assays, while DPPH, nitric oxide, hydrogen peroxide and superoxide free radical scavenging assays were tested to determine the antioxidant potential of M. pumilum. An in vitro scratch wound assay was performed to measure the fibroblast cell migration rate using normal and insulin-resistant human dermal fibroblast cells. (3) All M. pumilum fractions exhibited good antioxidant and fibroblast cell migration activity, among which fractions A and E displayed the greatest effect. (4) M. pumilum's fibroblast migration activity could be attributed to its strong antioxidant properties along with its previously reported properties.

Potential Synergistic Supplementation of NAD+ Promoting Compounds as a Strategy for Increasing Healthspan

Disrupted biological function, manifesting through the hallmarks of aging, poses one of the largest threats to healthspan and risk of disease development, such as metabolic disorders, cardiovascular ailments, and neurodegeneration. In recent years, numerous geroprotectors, senolytics, and other nutraceuticals have emerged as potential disruptors of aging and may be viable interventions in the immediate state of human longevity science. In this review, we focus on the decrease in nicotinamide adenine dinucleotide (NAD+) with age and the supplementation of NAD+ precursors, such as nicotinamide mononucleotide (NMN) or nicotinamide riboside (NR), in combination with other geroprotective compounds, to restore NAD+ levels present in youth. Furthermore, these geroprotectors may enhance the efficacy of NMN supplementation while concurrently providing their own numerous health benefits. By analyzing the prevention of NAD+ degradation through the inhibition of CD38 or supporting protective downstream agents of SIRT1, we provide a potential framework of the CD38/NAD+/SIRT1 axis through which geroprotectors may enhance the efficacy of NAD+ precursor supplementation and reduce the risk of age-related diseases, thereby potentiating healthspan in humans.

Systematic Insight of Resveratrol Activated SIRT1 Interactome through Proximity Labeling Strategy

SIRT1 functions by regulating the modification of proteins or interacting with other proteins to form complexes. It has been widely studied and found to play significant roles in various biological processes and diseases. However, systematic studies on activated-SIRT1 interactions remain limited. Here, we present a comprehensive SIRT1 interactome under resveratrol stimulation through proximity labeling methods. Our results demonstrated that RanGap1 interacted with SIRT1 in HEK 293T cells and MCF-7 cells. SIRT1 regulated the protein level of RanGap1 and had no obvious effect on RanGap1 transcription. Moreover, the overexpression of Rangap1 increased the ROS level in MCF-7 cells, which sensitized cells to resveratrol and reduced the cell viability. These findings provide evidence that RanGap1 interacts with SIRT1 and influences intracellular ROS, critical signals for mitochondrial functions, cell proliferation and transcription. Additionally, we identified that the SIRT1-RanGap1 interaction affects downstream signals induced by ROS. Overall, our study provides an essential resource for future studies on the interactions of resveratrol-activated SIRT1. There are conflicts about the relationship between resveratrol and ROS in previous reports. However, our data identified the impact of the resveratrol-SIRT1-RanGap1 axis on intracellular ROS.

Unexpected beta-amyloid production by middle doses of resveratrol through stabilization of APP protein and AMPK-mediated inhibition of trypsin-like proteasome activity in a cell model of Alzheimer's disease

Resveratrol is a drug candidate used for Alzheimer's disease (AD) and shows beneficial effects in various toxicity and production models, although recent clinical trial data did not show satisfactory results. Here we demonstrated the potential side effects of resveratrol in AD. We demonstrated resveratrol concentration- and time-dependent Aβ production using Aβ secreted cellular model and analyzed resveratrol-related molecular signaling. In Swedish mutant of APP (APPsw) stably expressing cells, treatment with a middle dose of resveratrol for 24 h unexpectedly increased Aβ production, but higher concentrations or shorter treatment durations did not. Resveratrol-mediated Aβ production was caused by an increase in APP protein levels associated with proteasome-dependent regulation of APP stability. Inhibition of AMPK, cAMP production, and epac1 attenuated Aβ production and APP increase by resveratrol, which blocked the inhibition of trypsin-like proteasomal activity. In addition, high-dose resveratrol decreased Aβ secretion and β-secretase activity at any treatment duration. Our data suggest that an appropriate dose of resveratrol can paradoxically increase Aβ production via stabilization of APP protein in an AMPK-proteasome signaling-dependent manner, which provides mechanistic insights into prior unsatisfactory clinical outcomes and the future clinical use of resveratrol.

Calorie restriction promotes remyelination in a Cuprizone-Induced demyelination mouse model of multiple sclerosis

Over the past few decades several attempts have been made to introduce a potential and promising therapy for Multiple sclerosis (MS). Calorie restriction (CR) is a dietary manipulation to reduce calorie intake which has been shown to improve neuroprotection and attenuate neurodegenerative disorders. Here, we evaluated the effect of 33% CR regimen for 4 weeks on the remyelination capacity of Cuprizone (CPZ) induced demyelination in a mouse model of MS. Results showed that CR induced a significant increase in motor coordination and balance performance in CPZ mice. Also, luxol fast blue (LFB) staining showed that CR regimen significantly improved the remyelination in the corpus callosum of CPZ + CR mice compared to the CPZ group. In addition, CR regimen significantly increased the transcript expression levels of BDNF, Sox2, and Sirt1 in the corpus callosum of CPZ mice, while decreasing the p53 levels. Moreover, CR regimen significantly decreased the apoptosis rate. Furthermore, astrogliosis (GFAP + astrocytes) and microgliosis (Iba-1 + microglia) were significantly decreased by CR regimen while oligodendrogenesis (Olig2+) and Sirt1 + cell expression were significantly increased in the corpus callosum of CPZ + CR mice compared to the CPZ group. In conclusion, CR regimen can promote remyelination potential in a CPZ-demyelinating mouse model of MS by increasing oligodendrocyte generation while decreasing their apoptosis.

Effect of Antioxidants on the Fibroblast Replicative Lifespan In Vitro

Replicative senescence is an unalterable growth arrest of primary cells in the culture system. It has been reported that aging in vivo is related to the limited replicative capacity that normal somatic cells show in vitro. If oxidative damage contributes to the lifespan limitation, antioxidants are expected to extend the replicative lifespan of fibroblasts. This article critically reviews the results of experiments devoted to this problem performed within the last decades under conditions of in vitro culture. The results of studied are heterogeneous, some papers showing no effects of antioxidants; most finding limited enhancement of reproductive capacity of fibroblasts, some reporting a significant extension of replicative lifespan (RLS). Both natural and synthetic antioxidants were found to extend the RLS of fibroblasts, either by a direct antioxidant effect or, indirectly, by activation of signaling pathways and activation of proteasomes or hormetic effects. Most significant prolongation of RLS was reported so far for nicotinamide, N-hydroxylamines, carnosine and Methylene Blue. These results may be of importance for the design of skin-protecting cosmetics.

Increased mitochondrial content and function by resveratrol and select flavonoids protects against benzo[a]pyrene-induced bioenergetic dysfunction and ROS generation in a cell model of neoplastic transformation

Dietary polyphenols act in cancer prevention and may inhibit carcinogenesis. A possible mitochondrial mechanism for carcinogen-induced neoplastic transformation and chemoprevention by polyphenols, however, is largely unexplored. Using the Bhas 42 cell model of carcinogen-induced neoplastic transformation, we investigated benzo[a]pyrene (B[a]P) along with different polyphenols for their effects on mitochondrial content and function, and on mitochondrial and intracellular ROS generation. Bhas 42 cells were either co-treated with 5 μM polyphenol starting 2 h before exposure to 4 μM B[a]P for 24 or 72 h, or pre-treated with polyphenol for 24 h and removed prior to B[a]P exposure. Exposure to B[a]P decreased mitochondrial content (by 46% after 24 h and 30% after 72 h), decreased mitochondrial membrane potential and cellular ATP, and increased generation of mitochondrial superoxide and intracellular ROS. Polyphenol co-treatments protected against the decreased mitochondrial content, with resveratrol being the most effective (increasing the mitochondrial content after 72 h by 75%). Measurements after 24 h of mRNA for mitochondria-related proteins and of SIRT1 enzyme activity suggested an involvement of increased mitochondrial biogenesis in the polyphenol effects. The polyphenol co-treatments also ameliorated B[a]P-induced deficits in mitochondrial function (most strongly resveratrol), and increases in generation of mitochondrial superoxide and intracellular ROS. Notably, 24 h pre-treatments with polyphenols strongly suppressed subsequent B[a]P-induced increases, after 24 and 72 h, in mitochondrial superoxide and intracellular ROS generation, with resveratrol being the most effective. In conclusion, the results support a mechanism for B[a]P carcinogenesis involving impaired mitochondrial function and increased mitochondria-derived ROS, that can be ameliorated by dietary polyphenols. The evidence supports an increase in mitochondrial biogenesis behind the strong chemoprevention by resveratrol, and a mitochondrial antioxidant effect in chemoprevention by quercetin.

Effects of Maternal Resveratrol on Maternal High-Fat Diet/Obesity with or without Postnatal High-Fat Diet

To examine the effects of maternal resveratrol in rats borne to dams with gestational high-fat diet (HFD)/obesity with or without postnatal high-fat diet. We first tested the effects of maternal resveratrol intake on placenta and male fetus brain in rats borne to dams with gestational HFD/obesity. Then, we assessed the possible priming effect of a subsequent insult, male offspring were weaned onto either a rat chow or a HFD. Spatial learning and memory were assessed by Morris water maze test. Blood pressure and peripheral insulin resistance were examined. Maternal HFD/obesity decreased adiponectin, phosphorylation alpha serine/threonine-protein kinase (pAKT), sirtuin 1 (SIRT1), and brain-derived neurotrophic factor (BDNF) in rat placenta, male fetal brain, and adult male offspring dorsal hippocampus. Maternal resveratrol treatment restored adiponectin, pAKT, and BDNF in fetal brain. It also reduced body weight, peripheral insulin resistance, increased blood pressure, and alleviated cognitive impairment in adult male offspring with combined maternal HFD and postnatal HFD. Maternal resveratrol treatment restored hippocampal pAKT and BDNF in rats with combined maternal HFD and postnatal HFD in adult male offspring dorsal hippocampus. Maternal resveratrol intake protects the fetal brain in the context of maternal HFD/obesity. It effectively reduced the synergistic effects of maternal HFD/obesity and postnatal HFD on metabolic disturbances and cognitive impairment in adult male offspring. Our data suggest that maternal resveratrol intake may serve as an effective therapeutic strategy in the context of maternal HFD/obesity.

Cordyceps cicadae Prevents Renal Tubular Epithelial Cell Apoptosis by Regulating the SIRT1/p53 Pathway in Hypertensive Renal Injury

Hypertensive renal injury is a primary etiology of end-stage renal disease, and satisfactory therapeutic strategies are urgently required. Cordyceps cicadae, a traditional Chinese herb, has potential renoprotective benefits and is widely used in the treatment of many kidney diseases. To investigate the mechanisms underlying the renoprotective effect of C. cicadae on hypertensive renal injury, we studied the effect of C. cicadae on tubular epithelial cells (TECs) in a spontaneously hypertensive rat (SHR) model and angiotensin II- (AngII-) cultured primary TECs. Our study showed that C. cicadae treatment could decrease 24-hour urine albumin, albumin-to-creatinine ratio (ACR), β2-MG level, and kidney injury molecule-1 (kim-1) level in SHR urine, alleviate interstitial fibrosis, and reduce α-smooth muscle actin (α-SMA) expression in SHR kidney. In primary TECs, medicated serum containing C. cicadae (CSM) might significantly reduce the AngII-induced production of kim-1 and neutrophil gelatinase-associated lipocalin (NGAL). Furthermore, C. cicadae treatment could decrease TEC apoptosis in SHRs as assessed by the terminal transferase-mediated biotin dUTP nick-end labeling (TUNEL) assay. CSM could inhibit caspase-3 activity and enhance cellular viability as measured by methyl thiazolyl tetrazolium in AngII-cultured TECs, suggesting that CSM might reduce the apoptosis level in TECs induced by AngII. We found that the SIRT1 expression level was markedly lowered, while the protein level of acetylated-p53 was elevated in the TECs of patients with hypertensive renal injury and SHRs. C. cicadae presented the effect of regulating the SIRT1/p53 pathway. Further SIRT1 inhibition with EX527 reversed the effect of C. cicadae on AngII-induced apoptosis. Taken together, our results indicate that C. cicadae offers a protective effect on TECs under hypertensive conditions, which may be related to its antiapoptotic effect through regulation of the SIRT1/p53 pathway.

NAD+ cellular redox and SIRT1 regulate the diurnal rhythms of tyrosine hydroxylase and conditioned cocaine reward

The diurnal regulation of dopamine is important for normal physiology and diseases such as addiction. Here we find a novel role for the CLOCK protein to antagonize CREB-mediated transcriptional activity at the tyrosine hydroxylase (TH) promoter, which is mediated by the interaction with the metabolic sensing protein, Sirtuin 1 (SIRT1). Additionally, we demonstrate that the transcriptional activity of TH is modulated by the cellular redox state, and daily rhythms of redox balance in the ventral tegmental area (VTA), along with TH transcription, are highly disrupted following chronic cocaine administration. Furthermore, CLOCK and SIRT1 are important for regulating cocaine reward and dopaminergic (DAergic) activity, with interesting differences depending on whether DAergic activity is in a heightened state and if there is a functional CLOCK protein. Taken together, we find that rhythms in cellular metabolism and circadian proteins work together to regulate dopamine synthesis and the reward value for drugs of abuse.

Resveratrol Inhibits MMP3 and MMP9 Expression and Secretion by Suppressing TLR4/NF-κB/STAT3 Activation in Ox-LDL-Treated HUVECs

Aim

Resveratrol is a natural plant polyphenol. The present study investigated the effects of resveratrol on the Toll-like receptor 4- (TLR4-) mediated expression and secretion of matrix metalloproteinases (MMPs) in oxidized low-density lipoprotein- (ox-LDL-) treated human umbilical vein endothelial cells (HUVECs).

Methods

Protein expression was analyzed by immunoblotting. The secretion of MMPs was measured by an enzyme-linked immunosorbent assay. The animal experiments were performed with and without resveratrol treatment in high-fat chow-fed mice.

Results

Resveratrol inhibited the expression of TLR4, MMP3, and MMP9 in ox-LDL- and lipopolysaccharide- (LPS-) treated HUVECs. Resveratrol reduced the secretion of MMP3 and MMP9 that was induced by ox-LDL and LPS. The TLR4 inhibitor CLI-095 similarly suppressed the expression and secretion of MMP3 and MMP9 in ox-LDL- and LPS-treated HUVECs. Resveratrol attenuated the phosphorylation of the transcription factors nuclear factor-κB (NF-κB) and signal transducer and activator of transcription 3 (STAT3) that was induced by ox-LDL and LPS. Resveratrol recovered Sirt1 expression. In the animal experiments, resveratrol decreased TLR4 expression in the aorta, MMP9 levels in plasma, and vascular structural changes in high-fat chow-fed mice, with no significant effect on plasma MMP3 levels.

Conclusion

Resveratrol inhibited the TLR4-mediated expression and secretion of MMP3 and MMP9 in ox-LDL-treated HUVECs. The mechanism of action of resveratrol may be associated with the suppression of NF-κB and STAT3 phosphorylation and restoration of Sirt1 expression. Resveratrol exerts protective effects against vascular structural changes in high-fat chow-fed mice.

Effect of Autophagy Regulated by Sirt1/FoxO1 Pathway on the Release of Factors Promoting Thrombosis from Vascular Endothelial Cells

Factors promoting thrombosis such as von Willebrand factor (vWF) and P-selectin are essential for the development of atherosclerosis (AS) and arterial thrombosis. The processing, maturation and release of vWF are regulated by autophagy of vascular endothelial cells. The Sirt1/FoxO1 pathway is an important pathway to regulate autophagy of endothelial cells, therefore the Sirt1/FoxO1 pathway may be an important target for the prevention of thrombosis. We investigated the role of ox-LDL in the release of vWF and P-selectin and the expression of Sirt1 and FoxO1 by Western Blot, Flow Cytometry, ELISA, and tandem fluorescent mRFP-GFP-LC3. We found that vWF and P-selectin secretion increased and Sirt1/FoxO1 pathway was depressed in human umbilical vein endothelial cells (HUVEC) when treated with ox-LDL. Moreover, the expression of autophagy-related protein LC3-II/I and p62 increased. Then, we explored the relationship between autophagy regulated by the Sirt1/FoxO1 pathway and the secretion of vWF and P-selectin. We found that Sirt1/FoxO1, activated by the Sirt1 activators resveratrol (RSV) and SRT1720, decreased the secretion of vWF and P-selectin, which can be abolished by the autophagy inhibitor 3-MA. The expression of Rab7 increased when Sirt1/FoxO1 pathway was activated, and the accumulation of p62 was decreased. Autophagy flux was inhibited by ox-LDL and Sirt1/FoxO1 pathway might enhance autophagy flux through the promotion of the Rab7 expression. Taken together, our data suggest that by enhancing autophagy flux and decreasing the release of vWF and P-selectin, the Sirt1/FoxO1 pathway may be a promising target to prevent AS and arterial thrombosis.

Cross-Talk between Sirtuin 1 and the Proinflammatory Mediator High-Mobility Group Box-1 in the Regulation of Blood-Retinal Barrier Breakdown in Diabetic Retinopathy

Purpose: High-mobility group box-1 (HMGB1) mediates inflammation and breakdown of blood-retinal barrier (BRB) in diabetic retina. Sirtuin-1 (SIRT1) has protective effects against inflammation and oxidative stress. The aim of this study was to investigate the interaction between HMGB1 and SIRT1 in regulating BRB breakdown in diabetic retina. Methods: BRB breakdown was assessed in vivo with fluorescein isothiocyanate-conjugated dextran. Vitreous samples from 47 proliferative diabetic retinopathy (PDR) and 19 nondiabetic patients, and epiretinal membranes from 13 patients with PDR were studied by enzyme-linked immunosorbent assay and immunohistochemistry. Retinas from 4-week diabetic rats and from normal rats intravitreally injected with HMGB1 were studied by spectrophotometric assay, Western blot analysis, and RT-PCR. We also studied the effect of the HMGB1 inhibitor glycyrrhizin and the SIRT1 activator resveratrol on diabetes-induced biochemical changes in the retina. Results: HMGB1 levels in vitreous samples from PDR patients were significantly higher than in nondiabetic controls, whereas SIRT1 levels were significantly lower in vitreous samples from patients with inactive PDR than those in patients with active PDR and nondiabetic controls. In epiretinal membranes, SIRT1 was expressed in vascular endothelial cells and stromal cells. Diabetes and intravitreal injection of HMGB1 in normal rats downregulated SIRT1expression, whereas glycyrrhizin and resveratrol normalized diabetes-induced downregulation of SIRT1. Resveratrol significantly attenuated diabetes-induced downregulation of occludin and upregulation of HMGB1 and receptor for advanced glycation end products in the retina and breakdown of BRB. Conclusions: Our findings suggest that a functional link between SIRT1 and HMGB1 is involved in regulating of BRB breakdown in diabetic retina.

MHY2233 Attenuates Replicative Cellular Senescence in Human Endothelial Progenitor Cells via SIRT1 Signaling

Cardiovascular diseases (CVDs) are a major cause of death worldwide. Due to the prevalence of many side effects and incomplete recovery from pharmacotherapies, stem cell therapy is being targeted for the treatment of CVDs. Among the different types of stem cells, endothelial progenitor cells (EPCs) have great potential. However, cellular replicative senescence decreases the proliferation, migration, and overall function of EPCs. Sirtuin 1 (SIRT1) has been mainly studied in the mammalian aging process. MHY2233 is a potent synthetic SIRT1 activator and a novel antiaging compound. We found that MHY2233 increased the expression of SIRT1, and its deacetylase activity thereby decreased expression of the cellular senescence biomarkers, p53, p16, and p21. In addition, MHY2233 decreased senescence-associated beta-galactosidase- (SA-β-gal-) positive cells and senescence-associated secretory phenotypes (SASPs), such as the secretion of interleukin- (IL-) 6, IL-8, IL-1α, and IL-1β. MHY2233 treatment protected senescent EPCs from oxidative stress by decreasing cellular reactive oxygen species (ROS) levels, thus enhancing cell survival and function. The angiogenesis, proliferation, and migration of senescent EPCs were enhanced by MHY2233 treatment. Thus, MHY2233 reduces replicative and oxidative stress-induced senescence in EPCs. Therefore, this novel antiaging compound MHY2233 might be considered a potent therapeutic agent for the treatment of age-associated CVDs.

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.

Impact of Red Wine Consumption on Cardiovascular Health

BACKGROUND

The devastating effects of heavy alcohol drinking have been long time recognized. In the last decades, potential benefits of modest red wine drinking were suggested. In European countries in which red wide intake is not negligible (such as France), the association between cholesterol and cardiovascular (CV) risk was less evident, suggesting the action of some protective molecules in red wine or other foods and drinks.

METHODS

This narrative review is based on the material searched for and obtained via PubMed up to May 2016. The search terms we used were: "red wine, cardiovascular, alcohol" in combination with "polyphenols, heart failure, infarction".

RESULTS

Epidemiological and mechanistic evidence of a J-shaped relationship between red wine intake and CV risk further supported the "French paradox". Specific components of red wine both in vitro and in animal models were discovered. Polyphenols and especially resveratrol largely contribute to CV prevention mainly through antioxidant properties. They exert beneficial effects on endothelial dysfunction and hypertension, dyslipidemia, metabolic diseases, thus reducing the risk of adverse CV events such as myocardial infarction ischemic stroke and heart failure. Of interest, recent studies pointed out the role of ethanol itself as a potential cardioprotective agent, but a clear epidemiological evidence is still missing. The aim of this narrative review is to update current knowledge on the intracellular mechanism underlying the cardioprotective effects of polyphenols and ethanol. Furthermore, we summarized the results of epidemiological studies, emphasizing their methodological criticisms and the need for randomized clinical trials able to clarify the potential role of red wine consumption in reducing CV risk.

CONCLUSION

Caution in avowing underestimation of the global burden of alcohol-related diseases was particularly used.

Resveratrol Can Be Stable in a Medium Containing Fetal Bovine Serum with Pyruvate but Shortens the Lifespan of Human Fibroblastic Hs68 Cells

This study is aimed at developing a method that can inhibit resveratrol (Res) degradation in Dulbecco's modified Eagle medium (DMEM) and at evaluating the effects of Res on the replicative lifespan of Hs68 cells. We hypothesized that Res can extend the lifespan of Hs68 cells if we can inhibit the oxidative degradation of Res in the medium. We found that the addition of ≥5 U/mL SOD to the medium could completely inhibit Res degradation in DMEM. Fetal bovine serum (FBS) contained 29.3 ± 1.1 U/mL of SOD activity. FBS could prevent Res degradation in the medium through SOD activity and Res–FBS interaction, but the regular FBS concentration (i.e., 10% FBS) exhibited an insufficient ability to completely inhibit Res degradation. We found that pyruvate (1 mM) could potentiate SOD to scavenge superoxide at approximately 2.2-fold. Thus, 10% FBS combined with pyruvate (1 mM) could completely inhibit Res degradation. When Res was not degraded, it still shortened the lifespan of Hs68 cells. Overall, the proposed method involving 10% FBS combined with pyruvate (1 mM) could completely prevent Res degradation. However, in contrast to our hypothesis, Res could induce the shortening of the lifespan of Hs68 cells. The stability of Res analogs (i.e., oxy-Res and acetyl-Res) in the medium and their effects on the lifespan of Hs68 cells were also investigated.

[Resveratrol regulate the extracellular matrix expression via Wnt/β-catenin pathway in nucleus pulposus cells]

Objective

To investigate the regulatory effect of resveratrol (RES) on the extracellular matrix (ECM) expression of nucleus pulposus cells (NPC), and its relative molecular mechanism.

Methods

Ten patients receiving discectomy were collected, of which 5 patients were young with spinal burst fracture, classified as control group; the rest 5 patients were senile with lumbar disc herniation, classified as degenerative group. The nucleus pulposus tissue of 2 groups were collected, the in situexpression of β-catenin was detected by immunohistochemistry, and the protein expressions of collagen type Ⅱ and Aggrecan were detected by Western blot. The NPC were isolated and cultured from degenerative nucleus pulposus tissues. RES treated the third-passage NPC with (group B) or without IL-1β (group C), to further determine the protein expressions of collagen type Ⅱ and Aggrecan by Western blot, the unstimulated cells were set up as blank control group (group A). Moreover, NPC treated with small interfering RNA (siRNA) targeted silent SIRT1 or β-catenin were used to determine the protein and gene expressions of β-catenin and SIRT1 by Western blot and real-time fluorescence quantitative PCR. In addition, the third-passage NPC treated with complete medium (group 1), IL-1β (group 2), RES+IL-1β (group 3), and SIRT1-siRNA+RES+IL-1β (group 4) for 24 hours were used to detect the nuclear translocation of β-catenin by cell immunofluorescence staining. Finally, the third-passage NPC treated with complete medium (group Ⅰ), IL-1β (group Ⅱ), IL-1β+β-catenin-siRNA (group Ⅲ), IL-1β+RES (group Ⅳ), and IL-1β+RES+SIRT1-siRNA (group Ⅴ) for 24 hours were used to detect the protein expressions of collagen type Ⅱ and Aggrecan by Western blot.

Results

Immunohistochemical staining and Western blot detection showed that when compared with control group, the cell proportion of expression of β-catenin were significantly increased in degenerative group ( t=4.616, P=0.010); the protein expression of β-catenin was also significantly increased and the protein expressions of collagen type Ⅱ and Aggrecan were significantly decreased ( P<0.05). In cytology experiments, the protein expression of β-catenin in group B was significantly higher than that in groups A and C, and the protein expressions of collagen type Ⅱ and Aggrecan in group B were significantly lower than those in groups A and C ( P<0.05). After transfection of siRNA, the protein expressions of SIRT1 and β-catenin significantly decreased ( P<0.05). The results of cell immunofluorescence staining further confirmed that when compared with group 3, after the SIRT1 was silenced by siRNA in group 4, the attenuated nuclear translocation of β-catenin by RES treatment was aggravated. Western blot results showed that the protein expressions of collagen type Ⅱ and Aggrecan in group Ⅱ were significantly lower than those in group Ⅰ( P<0.05); after transfection of β-catenin-siRNA in group Ⅲ, the degradation of ECM by IL-1β was obviously inhibited, the protein expressions of collagen type Ⅱ and Aggrecan were significantly increased when compared with group Ⅱ ( P<0.05); after transfection of SIRT1-siRNA in group Ⅴ, the protective effect of RES on the degradation of ECM was inhibited, the protein expressions of collagen type Ⅱ and Aggrecan were significantly decreased when compared with group Ⅳ ( P<0.05).

Conclusion

RES regulates the ECM expression of NPC via Wnt/β-catenin signaling pathway, which provide a new idea for intervertebral disc degeneration disease treatment.

The neurotoxicity of iron, copper and cobalt in Parkinson's disease through ROS-mediated mechanisms

Parkinson's disease (PD) is the second most common neurodegenerative disease with gradual loss of dopaminergic neurons. Despite extensive research in the past decades, the etiology of PD remains elusive. Nevertheless, multiple lines of evidence suggest that oxidative stress is one of the common causes in the pathogenesis of PD. It has also been suggested that heavy metal-associated oxidative stress may be implicated in the etiology and pathogenesis of PD. Here we review the roles of redox metals, including iron, copper and cobalt, in PD. Iron is a highly reactive element and deregulation of iron homeostasis is accompanied by concomitant oxidation processes in PD. Copper is a key metal in cell division process, and it has been shown to have an important role in neurodegenerative diseases such as PD. Cobalt induces the generation of reactive oxygen species (ROS) and DNA damage in brain tissues.

Effects of natural mineral-rich water consumption on the expression of sirtuin 1 and angiogenic factors in the erectile tissue of rats with fructose-induced metabolic syndrome

Consuming a high-fructose diet induces metabolic syndrome (MS)-like features, including endothelial dysfunction. Erectile dysfunction is an early manifestation of endothelial dysfunction and systemic vascular disease. Because mineral deficiency intensifies the deleterious effects of fructose consumption and mineral ingestion is protective against MS, we aimed to characterize the effects of 8 weeks of natural mineral-rich water consumption on the structural organization and expression of vascular growth factors and receptors on the corpus cavernosum (CC) in 10% fructose-fed Sprague-Dawley rats (FRUCT). Differences were not observed in the organization of the CC either on the expression of vascular endothelial growth factor (VEGF) or the components of the angiopoietins/Tie2 system. However, opposing expression patterns were observed for VEGF receptors (an increase and a decrease for VEGFR1 and VEGFR2, respectively) in FRUCT animals, with these patterns being strengthened by mineral-rich water ingestion. Mineral-rich water ingestion (FRUCTMIN) increased the proportion of smooth muscle cells compared with FRUCT rats and induced an upregulatory tendency of sirtuin 1 expression compared with the control and FRUCT groups. Western blot results were consistent with the dual immunofluorescence evaluation. Plasma oxidized low-density lipoprotein and plasma testosterone levels were similar among the experimental groups, although a tendency for an increase in the former was observed in the FRUCTMIN group. The mineral-rich water-treated rats presented changes similar to those observed in rats treated with MS-protective polyphenol-rich beverages or subjected to energy restriction, which led us to hypothesize that the effects of mineral-rich water consumption may be more vast than those directly observed in this study.

Properties of Resveratrol: In Vitro and In Vivo Studies about Metabolism, Bioavailability, and Biological Effects in Animal Models and Humans

Plants containing resveratrol have been used effectively in traditional medicine for over 2000 years. It can be found in some plants, fruits, and derivatives, such as red wine. Therefore, it can be administered by either consuming these natural products or intaking nutraceutical pills. Resveratrol exhibits a wide range of beneficial properties, and this may be due to its molecular structure, which endow resveratrol with the ability to bind to many biomolecules. Among these properties its activity as an anticancer agent, a platelet antiaggregation agent, and an antioxidant, as well as its antiaging, antifrailty, anti-inflammatory, antiallergenic, and so forth activities, is worth highlighting. These beneficial biological properties have been extensively studied in humans and animal models, both in vitro and in vivo. The issue of bioavailability of resveratrol is of paramount importance and is determined by its rapid elimination and the fact that its absorption is highly effective, but the first hepatic step leaves little free resveratrol. Clarifying aspects like stability and pharmacokinetics of resveratrol metabolites would be fundamental to understand and apply the therapeutic properties of resveratrol.

Resveratrol relieves ischemia-induced oxidative stress in the hippocampus by activating SIRT1

Resveratrol, a naturally occurring phytoalexin, acts as an activator of sirtuin 1 (SIRT1) and has been shown to have a neuroprotective role in various models. Healthy adult male Sprague-Dawley rats were subjected to cerebral ischemia in order to study the protective effect of resveratrol on the brain following ischemia, and to investigate the effects of SIRT1 activation on the hippocampus. Untreated and resveratrol-treated rats were anesthetized prior to undergoing surgery to induce middle cerebral artery occlusion followed by reperfusion. SIRT1 expression was evaluated by immunohistochemistry, western blotting and reverse transcription-quantitative polymerase chain reaction, and SIRT1 activity was also evaluated. In addition, terminal deoxynucleotidyl transferase dUTP nick end-labeling (TUNEL) and Nissl staining assays were conducted and the levels of reactive oxygen species were determined. It was observed that resveratrol significantly decreased the number of TUNEL-positive cells and increased the expression of SIRT1 mRNA in a dose-dependent manner. This was accompanied by increases in SIRT1 protein expression levels and SIRT1 activity. The results demonstrate the neuroprotective and antioxidant effects of resveratrol against ischemia-induced apoptosis in the rat hippocampus.

Sirtuin 1: A Target for Kidney Diseases

Sirtuin 1 (SIRT1) is an evolutionarily conserved NAD(+)-dependent histone deacetylase that is necessary for caloric restriction-related lifespan extension. SIRT1, as an intracellular energy sensor, detects the concentration of intracellular NAD(+) and uses this information to adapt cellular energy output to cellular energy requirements. Previous studies on SIRT1 have confirmed its beneficial effects on cellular immunity to oxidative stress, reduction of fibrosis, suppression of inflammation, inhibition of apoptosis, regulation of metabolism, induction of autophagy and regulation of blood pressure. All of the above biological processes are involved in the pathogenesis of kidney diseases. Therefore, the activation of SIRT1 may become a therapeutic target to improve the clinical outcome of kidney diseases. In this review, we give an overview of SIRT1 and its molecular targets as well as SIRT1-modulated biological processes, with a particular focus on the role of SIRT1 in kidney diseases.

Modulation of tumorigenesis by dietary intervention is not mediated by SIRT1 catalytic activity

The protein deacetylase SIRT1 is involved in the regulation of a large number of cellular processes that are thought to be required for cancer initiation and progression. Both SIRT1 activity and tumorigenesis can be influenced by dietary fat and polyphenolics. We set out to determine whether dietary modulations of tumorigenesis are mediated by SIRT1 catalytic functions. We introduced a mammary gland tumor-inducing transgene, MMTV-PyMT, into stocks of mice bearing a H355Y point mutation in the Sirt1 gene that abolishes SIRT1 catalytic activity. Tumor latency was reduced in animals fed a high fat diet but this effect was not dependent on SIRT1 activity. Resveratrol had little effect on tumor formation except in animals heterozygous for the mutant Sirt1 gene. We conclude that the effects of these dietary interventions on tumorigenesis are not mediated by modulation of SIRT1 catalytic activity.

High-mobility group box 1 is a novel deacetylation target of Sirtuin1

High mobility group box 1 (HMGB1) undergoes acetylation, nuclear-to-cytoplasmic translocation and release from stressed kidneys, unleashing a signaling cascade of events leading to systemic inflammation. Here we tested whether the deacetylase activity of Sirtuin1 (SIRT1) participates in regulating nuclear retention of HMGB1 to ultimately modulate damage signaling initiated by HMGB1 secretion during stress. When immunoprecipitated acetylated HMGB1 was incubated with SIRT1, HMGB1 acetylation decreased by 57%. Proteomic analysis showed that SIRT1 deacetylates HMGB1 at four lysine residues (55, 88, 90 and 177) within the pro-inflammatory and nuclear localization signal domains of HMGB1. Genetic ablation or pharmacological inhibition of SIRT1 in endothelial cells increased HMGB1 acetylation and translocation. In vivo, deletion of SIRT1 reduced nuclear HMGB1 while increasing its acetylation and release into circulation during basal and ischemic conditions causing increased renal damage. Conversely, resveratrol pretreatment led to decreased HMGB1 acetylation, its nuclear retention, decreased systemic release and reduced tubular damage. Thus, a vicious cycle is set into motion in which the inflammation-induced repression of SIRT1 disables deacetylation of HMGB1, facilitates its nuclear-to-cytoplasmic translocation and systemic release, thereby maintaining inflammation.

Resveratrol metabolism in a non-human primate, the grey mouse lemur (Microcebus murinus), using ultra-high-performance liquid chromatography-quadrupole time of flight

The grey mouse lemur (Microcebus murinus) is a non-human primate used to study the ageing process. Resveratrol is a polyphenol that may increase lifespan by delaying age-associated pathologies. However, no information about resveratrol absorption and metabolism is available for this primate. Resveratrol and its metabolites were qualitatively and quantitatively analyzed in male mouse-lemur plasma (after 200 mg.kg⁻¹ of oral resveratrol) by ultra-high performance liquid chromatography (UHPLC), coupled to a quadrupole-time-of-flight (Q-TOF) mass spectrometer used in full-scan mode. Data analyses showed, in MS^E mode, an ion common to resveratrol and all its metabolites: m/z 227.072, and an ion common to dihydro-resveratrol metabolites: m/z 229.08. A semi-targeted study enabled us to identify six hydrophilic resveratrol metabolites (one diglucurono-conjugated, two monoglucurono-conjugated, one monosulfo-conjugated and two both sulfo- and glucurono-conjugated derivatives) and three hydrophilic metabolites of dihydro-resveratrol (one monoglucurono-conjugated, one monosulfo-conjugated, and one both sulfo- and glucurono-conjugated derivatives). The presence of such metabolites has been already detected in the mouse, rat, pig, and humans. Free resveratrol was measurable for several hours in mouse-lemur plasma, and its two main metabolites were trans-resveratrol-3-O-glucuronide and trans-resveratrol-3-sulfate. Free dihydro-resveratrol was not measurable whatever the time of plasma collection, while its hydrophilic metabolites were present at 24 h after intake. These data will help us interpret the effect of resveratrol in mouse lemurs and provide further information on the inter-species characteristics of resveratrol metabolism.

Sirtuins' modulation of autophagy

The sirtuin family of class III histone deacetylases has been extensively implicated in modulating a myriad of cellular processes, including energy metabolism, stress response, cell/tissue survival and malignancy. Recent studies have also identified multifaceted roles for Sirt1 and Sirt2 in the regulation of autophagy. Sirt1 could influence autophagy directly via its deacetylation of key components of the autophagy induction network, such as the products of autophagy genes (Atg) 5, 7, and 8. Nucleus-localized Sirt1 is also known to induce the expression of autophagy pathway components through the activation of FoxO transcription factor family members. The perception of a linear Sirt1-FoxO axis in autophagy induction is complicated by recent findings that acetylated FoxO1 could bind to Atg7 in the cytoplasm and affect autophagy directly. This occurs with prolonged stress signaling, with FoxO1's continuous dissociation from cytoplasmic Sirt2 and its consequential hyperacetylation. FoxO-mediated nuclear transcription may induce/enhance autophagy in ways that are different compared to cytoplasmic FoxO, thereby leading to contrasting (cell survival versus cell death) outcomes. FoxO and Sirt1 are both subjected to regulation by stress signaling (e.g., through the c-Jun N-terminal kinases (JNK)) in the context of autophagy induction, which are also critical in determining between cell survival and death in a context-dependent manner. We discussed here the emerging molecular intricacies of sirtuins' connections with autophagy. A good understanding of these connections would serve to consolidate a framework of mechanisms underlying Sirt1's protective effects in multiple physiological systems.

Essential role of AKT in tumor cells addicted to FGFR

Tumor cells with genetic amplifications or mutations in the fibroblast growth factor receptor (FGFR) family are often addicted to FGFR and heavily dependent on its signaling to survive. Although it is critical to understand which signaling pathway downstream of FGFR plays an essential role to guide the research and development of FGFR inhibitors, it has remained unclear partly because the tool compounds used in the literature also hit many other kinases, making the results difficult to interpret. With the development of a potent FGFR-specific inhibitor, BGJ398, we are now able to dissect various pathways with low drug concentrations to minimize multiple-target effects. Importantly, here, we show that inhibition of FGFR signaling by BGJ398 leads to only transient inhibition of ERK1/2 phosphorylation, whereas the inhibitory effect on AKT phosphorylation is sustainable, indicating that AKT, not ERK as commonly believed, serves as an appropriate pharmacodynamic biomarker for BGJ398. Although AKT inhibition by a pan-PI3K inhibitor alone has almost no effect on cell growth, heterologous expression of myr-AKT, an active form of AKT, rescues BGJ398-mediated suppression of tumor cell proliferation. These results indicate that AKT is an essential component downstream of FGFR. Finally, combination of the FGFR inhibitor BGJ398 with rapamycin significantly inhibits AKT phosphorylation and enhances their antiproliferative effects in FGFR-addicted cells, suggesting an effective combination strategy for clinical development of FGFR inhibitors.

Resveratrol differentially regulates NAMPT and SIRT1 in Hepatocarcinoma cells and primary human hepatocytes

Resveratrol is reported to possess chemotherapeutic properties in several cancers. In this study, we wanted to investigate the molecular mechanisms of resveratrol-induced cell cycle arrest and apoptosis as well as the impact of resveratrol on NAMPT and SIRT1 protein function and asked whether there are differences in hepatocarcinoma cells (HepG2, Hep3B cells) and non-cancerous primary human hepatocytes. We found a lower basal NAMPT mRNA and protein expression in hepatocarcinoma cells compared to primary hepatocytes. In contrast, SIRT1 was significantly higher expressed in hepatocarcinoma cells than in primary hepatocytes. Resveratrol induced cell cycle arrest in the S- and G2/M- phase and apoptosis was mediated by activation of p53 and caspase-3 in HepG2 cells. In contrast to primary hepatocytes, resveratrol treated HepG2 cells showed a reduction of NAMPT enzymatic activity and increased p53 acetylation (K382). Resveratrol induced NAMPT release from HepG2 cells which was associated with increased NAMPT mRNA expression. This effect was absent in primary hepatocytes where resveratrol was shown to function as NAMPT and SIRT1 activator. SIRT1 inhibition by EX527 resembled resveratrol effects on HepG2 cells. Furthermore, a SIRT1 overexpression significantly decreased both p53 hyperacetylation and resveratrol-induced NAMPT release as well as S-phase arrest in HepG2 cells. We could show that NAMPT and SIRT1 are differentially regulated by resveratrol in hepatocarcinoma cells and primary hepatocytes and that resveratrol did not act as a SIRT1 activator in hepatocarcinoma cells.

When is Sirt1 activity bad for dying neurons?

Sirt1, the class III histone deacetylase, is generally associated with increased life span and with a pro-survival effect in neurons stressed by pathological factors. Recent work, however, suggests that Sirt1 silencing could also promote neuronal survival. A possible reason suggested is Sirt1 silencing enhanced expression of both IGF-1 and IGF-1 receptor, signaling from which promotes survival. This work adds to the small but steady stream of findings that are diametrically opposite to the overwhelmingly large amount of evidence supporting a beneficial effect of sustaining or enhancing Sirt1 activity in neuronal injuries and diseases. We attempt to reconcile this discrepancy below by noting evidence that elevated Sirt1 levels and/or activity may not help, and could even adversely exacerbates demise, during events of acute neuronal damage or death. However, sustained Sirt1 activation will be beneficial in situations of chronic and long-term sub-lethal stresses, and the status of IGF-1 signaling may influence Sirt1 action in a context dependent manner.

Resveratrol mainly stimulates the glycolytic ATP synthesis flux and not the mitochondrial one: a saturation transfer NMR study in perfused and isolated rat liver

Our aim was to monitor the effects of resveratrol (RSV) on the respective contribution of glycolysis and oxidative phosphorylation on the unidirectional flux of ATP synthesis in whole isolated rat liver perfused with Krebs-Henseleit Buffer (KHB). The rate of tissular ATP supply was measured directly by monitoring the chemical exchange Pi toward ATP with saturation transfer (ST) (31)P nuclear magnetic resonance, a method applied for the first time for studying the effects of RSV. ST allows the measurement of the total cellular Pi→ATP chemical exchange; after specific inhibition of glycolysis with iodacetate, ST could provide the Pi→ATP flux issued from mitochondria. This latter was compared to mitochondrial ATP turn-over evaluated after chemical ischemia (CI), performed with specific inhibition (KCN) of oxidative phosphorylation, and measured by standard (31)P NMR spectroscopy. In controls (KHB alone), the apparent time constant (ks) of Pi exchange toward ATP as measured by ST was 0.48±0.04s(-1) leading to a total ATP synthesis rate of 37±3.9μmolmin(-1)g(-1). KHB+RSV perfusion increased ks (+52%; p=0.0009 vs. KHB) leading to an enhanced rate of total ATP synthesis (+52%; p=0.01 vs. KHB). When glycolysis was previously inhibited in KHB, both ks and ATP synthesis flux dramatically decreased (-87% and -86%, respectively, p<0.0001 vs. KHB without inhibition), evidencing a collapse of Pi-to-ATP exchange. However, glycolysis inhibition in KHB+RSV reduced to less extent ks (-41%, p=0.0005 vs. KHB+RSV without inhibition) and ATP synthesis flux (-18%). Using the CI method in KHB and KHB+RSV, KCN addition after glycolysis inhibition induced a rapid fall to zero of the ATP content. The mitochondrial ATP turnover R(t0) and its time constant kd mito were similar in KHB (1.18±0.19μmolmin(-1)g(-1) and 0.91±0.13min(-1)) and KHB+RSV (1.36±0.26μmolmin(-1)g(-1) and 0.77±0.18min(-1)). Since mitochondrial ATP turnover was not increased by RSV, the stimulation of Pi-to-ATP exchange by RSV mainly reflected an increase in glycolytic ATP synthesis flux. Moreover, the maintenance by RSV of a high level of Pi-to-ATP exchange after glycolysis inhibition evidenced a protective effect of the polyphenol, in agreement with our previous hypothesis of a stimulation of substrate flux throughout the glycolysis 3-carbon step.

Resveratrol as a pan-HDAC inhibitor alters the acetylation status of histone [corrected] proteins in human-derived hepatoblastoma cells

The polyphenolic alcohol resveratrol has demonstrated promising activities for the prevention and treatment of cancer. Different modes of action have been described for resveratrol including the activation of sirtuins, which represent the class III histone deacetylases (HDACs). However, little is known about the activity of resveratrol on the classical HDACs of class I, II and IV, although these classes are involved in cancer development or progression and inhibitors of HDACs (HDACi) are currently under investigation as promising novel anticancer drugs. We could show by in silico docking studies that resveratrol has the chemical structure to inhibit the activity of different human HDAC enzymes. In vitro analyses of overall HDAC inhibition and a detailed HDAC profiling showed that resveratrol inhibited all eleven human HDACs of class I, II and IV in a dose-dependent manner. Transferring this molecular mechanism into cancer therapy strategies, resveratrol treatment was analyzed on solid tumor cell lines. Despite the fact that hepatocellular carcinoma (HCC) is known to be particularly resistant against conventional chemotherapeutics, treatment of HCC with established HDACi already has shown promising results. Testing of resveratrol on hepatoma cell lines HepG2, Hep3B and HuH7 revealed a dose-dependent antiproliferative effect on all cell lines. Interestingly, only for HepG2 cells a specific inhibition of HDACs and in turn a histone hyperacetylation caused by resveratrol was detected. Additional testing of human blood samples demonstrated a HDACi activity by resveratrol ex vivo. Concluding toxicity studies showed that primary human hepatocytes tolerated resveratrol, whereas in vivo chicken embryotoxicity assays demonstrated severe toxicity at high concentrations. Taken together, this novel pan-HDACi activity opens up a new perspective of resveratrol for cancer therapy alone or in combination with other chemotherapeutics. Moreover, resveratrol may serve as a lead structure for chemical optimization of bioavailability, pharmacology or HDAC inhibition.

Exercise- and resveratrol-mediated alterations in adipose tissue metabolism

Owing to its obligatory role in locomotion and the fact that it accounts for the vast majority of whole-body glucose and lipid oxidation, much work has focused on studying the biochemical adaptations that occur in skeletal muscle in response to exercise. However, over the past several years there has been a growing appreciation that adipose tissue is an important player in regulating systemic carbohydrate and lipid homeostasis. Despite this, the examination of how exercise alters adipose tissue function and metabolism is, when compared with skeletal muscle, in its infancy. The purpose of the current review is to highlight some of the recent findings from our laboratory and others that focus on the emerging area of adipose tissue exercise biochemistry. Specifically, the role of exercise on the induction of mitochondrial and glyceroneogenic enzymes will be examined and will be compared with the well-characterized effects of thiazolidinediones, which are insulin-sensitizing drugs. A particular emphasis will be placed on the role of interleukin-6 in mediating the effects of exercise. Finally, we will discuss recent data from our laboratory demonstrating beneficial effects of resveratrol supplementation on adipose tissue metabolism.

Effects of resveratrol on daily rhythms of locomotor activity and body temperature in young and aged grey mouse lemurs

In several species, resveratrol, a polyphenolic compound, activates sirtuin proteins implicated in the regulation of energy balance and biological clock processes. To demonstrate the effect of resveratrol on clock function in an aged primate, young and aged mouse lemurs (Microcebus murinus) were studied over a 4-week dietary supplementation with resveratrol. Spontaneous locomotor activity and daily variations in body temperature were continuously recorded. Reduction in locomotor activity onset and changes in body temperature rhythm in resveratrol-supplemented aged animals suggest an improved synchronisation on the light-dark cycle. Resveratrol could be a good candidate to restore the circadian rhythms in the elderly.

Influences of histone deacetylase inhibitors and resveratrol on DNA repair and chromatin compaction

Accessibility of DNA is a prerequisite for both DNA damage and repair. Therefore, the chromatin structure is expected to have major impact on both processes, with opposite consequences for the stability of the genome. To analyse the influence of chromatin compaction on the generation and repair of various types of DNA modifications, we modulated the global chromatin structure of AS52 Chinese hamster ovary cells and HeLa cells by treatment with either histone deacetylase inhibitors or resveratrol and measured the repair kinetics of (i) pyrimidine dimers induced by ultraviolet B, (ii) oxidised purines generated by photosensitisation and (iii) single-strand breaks induced by H2O2, using an alkaline elution technique. The decrease of chromatin compaction (detected as reduced DNA accessibility to DNase I) after treatment with trichostatin A or butyrate slightly increased the damage generation but had no significant effect on the global repair rates. In contrast, incubation of AS52 cells with resveratrol at concentrations that caused significant chromatin compaction and that had only moderate influence on cell proliferation gave rise to a strong decrease of the repair rates of all three types of DNA modifications. Similar, but less pronounced effects were observed in HeLa cells. The effects of resveratrol on the repair rates were not antagonised by the sirtuin inhibitor EX-527 or by an increase of the intracellular thiol levels.

Acetal derivatives as prodrugs of resveratrol

The pharmacological exploitation of resveratrol is hindered by rapid phase-II conjugative metabolism in enterocytes and hepatocytes. One approach to the solution of this problem relies on prodrugs. We report the synthesis and characterization as well as the assessment of in vivo absorption and metabolism of a set of prodrugs of resveratrol in which the OH groups are engaged in the formal (-OCH2OR) or the more labile acetal (-OCH(CH3)OR) linkages. As carrier group (R) of the prodrug, we have used short ethyleneglycol oligomers (OEG) capped by a terminal methoxy group: -O-(CH2CH2O)n-CH3 (n = 0, 1, 2, 3, 4, 6). These moieties are expected to exhibit, to a degree, the favorable properties of longer polyethyleneglycol (PEG) chains, while their relatively small size makes for a more favorable drug loading capacity. After administration of formal-based prodrugs to rats by oral gavage, significant concentrations of derivatives were measured in blood samples over several hours, in all cases except for n = 0. Absorption was maximal for n = 4. Complete deprotection to give resveratrol and its metabolites was however too slow to be of practical use. Administration of the acetal prodrug carrying tetrameric OEG chains resulted instead in the protracted presence of resveratrol metabolites in blood, consistent with a progressive regeneration of the parent molecule from the prodrug after its absorption. The results suggest that prodrugs of polyphenols based on the acetal bond and short ethyleneglycol oligomers of homogeneous size may be a convenient tool for the systemic delivery of the unconjugated parent compound.

Blueberry consumption prevents loss of collagen in bone matrix and inhibits senescence pathways in osteoblastic cells

Ovariectomy (OVX)-induced bone loss has been linked to increased bone turnover and higher bone matrix collagen degradation as the result of osteoclast activation. However, the role of degraded collagen matrix in the fate of resident bone-forming cells is unclear. In this report, we show that OVX-induced bone loss is associated with profound decreases in collagen 1 and Sirt1. This was accompanied by increases in expression and activity of the senescence marker collagenase and expression of p16/p21 in bone. Feeding a diet supplemented with blueberries (BB) to pre-pubertal rats throughout development or only prior to puberty [postnatal day 21 (PND21) to PND34] prevents OVX-induced effects on expression of these molecules at PND68. In order to provide more evidence and gain a better understanding on the association between bone collagen matrix and resident bone cell fate, in vitro studies on the cellular senescence pathway using primary calvarial cells and three cell lines (ST2 cells, OB6, and MLO-Y4) were conducted. We found that senescence was inhibited by collagen in a dose-response manner. Treatment of cells with serum from OVX rats accelerated osteoblastic cell senescence pathways, but serum from BB-fed OVX rats had no effect. In the presence of low collagen or treatment with OVX rat serum, ST2 cells exhibited higher potential to differentiate into adipocytes. Finally, we demonstrated that bone cell senescence is associated with decreased Sirt1 expression and activated p53, p16, and p21. These results suggest that (1) a significant prevention of OVX-induced bone cell senescence from adult rats can occur after only 14 days consumption of a BB-containing diet immediately prior to puberty, and (2) the molecular mechanisms underlying this effect involves, at least in part, prevention of collagen degradation.

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.

Resveratrol and related stilbenes: their anti-aging and anti-angiogenic properties

Dietary stilbenes comprise a class of natural compounds that display significant biological activities of medicinal interest. Among them, their antioxidant, anti-aging and anti-angiogenesic properties are well established and subjects of numerous research endeavors. This mini-review aspires to account and present the literature reports published on research concerning various natural and synthetic stilbenes, such as trans-resveratrol. Special focus was given to most recent research findings, while the mechanisms underlying their anti-aging and anti-angiogenic effects as well as the respective signaling pathways involved were also presented and discussed.

Acute effects of resveratrol to enhance cocaine-induced dopamine neurotransmission in the striatum

Resveratrol is known as an activator of SIRT1, which leads to the deacetylation of histone and non-histone protein substrates, but also has other pharmacological profiles such as the inhibition of monoamine oxidase (MAO)-A and MAO-B. Resveratrol was previously demonstrated to potentiate the rewarding effects of chronic cocaine via activation of SIRT1. However, the role of resveratrol in cocaine responses in the acute phase remains unexplored. Therefore, we investigated the acute effects of resveratrol on cocaine-stimulated dopamine neurotransmission by analyzing protein phosphorylation in neostriatal slices. Treatment with resveratrol (50μM for 30min) enhanced cocaine-induced increases in the phosphorylation of DARPP-32 at Thr34 and GluA1 at Ser845, postsynaptic substrates for dopamine/D1 receptor/PKA signaling, and a cocaine-induced decrease in the phosphorylation of tyrosine hydroxylase at Ser40, a presynaptic substrate for dopamine/D2 receptor signaling. The inhibition of both MAO-A and MAO-B by clorgyline and pargyline, respectively, enhanced the effects of cocaine on DARPP-32 phosphorylation. The acute effect of resveratrol on cocaine-induced DARPP-32 phosphorylation was occluded with inhibition of MAO-A and MAO-B. In behavioral studies, resveratrol (40mg/kg, s.c.) enhanced the increase in locomotor activity induced by acute cocaine administration (10mg/kg, i.p.). Thus, this study provides pharmacological evidence that acute resveratrol enhances cocaine-induced dopamine neurotransmission and behavioral responses, presumably via mechanisms involving the inhibition of dopamine catabolism by MAO-A and MAO-B. Resveratrol may be useful to treat dysregulated dopamine neurotransmission, but it may enhance the risk of developing drug addiction.

The ways and means that fine tune Sirt1 activity

Sirt1 is the most evolutionarily conserved mammalian sirtuin. It plays a vital role in the regulation of metabolism, stress responses, genome stability, and ultimately aging. Although much attention has focused on the identification of the cellular targets and functional networks controlled by Sirt1, the mechanisms that regulate Sirt1 activity by biological stimuli have only recently begun to emerge. As an enzyme, the activity of Sirt1 can be controlled by the availability of its substrates, post-translational modifications, interactions with other proteins, or changes in its expression levels. In this review, we briefly discuss the ways and means by which the activity of Sirt1 is fine-tuned under different conditions.

Resveratrol protects against age-associated infertility in mice

STUDY QUESTION

Does resveratrol counteract age-associated infertility in a mouse model of reproductive aging?

SUMMARY ANSWER

Long-term-oral administration of resveratrol protects against the reduction of fertility with reproductive aging in mice.

WHAT IS KNOWN ALREADY

Loss of oocytes and follicles and reduced oocyte quality contribute to age-associated ovarian aging and infertility. Accumulation of free radicals with age leads to DNA mutations, protein damage, telomere shortening, apoptosis and accelerated ovarian aging. Increasing evidence shows that resveratrol, enriched in certain foods, for example red grapes and wine, has anti-tumor and anti-aging effects on somatic tissues by influencing various signaling pathways, including anti-oxidation, as well as activating Sirt1 and telomerase. We investigated the potential of resveratrol to stave off ovarian aging in the inbred C57/BL6 mouse model.

STUDY DESIGN, SIZE, DURATION

Young C57/BL6 females (aged 2-3 months) were fed with resveratrol added to drinking water at 30 mg/l (providing ∼7.0 mg/kg/day) for 6 or 12 months, and the fertility and ovarian functions were compared among mice treated with or without resveratrol, and young mice served as reproductive controls. Experiments were repeated three times, with an average of 25 females randomly allocated to each treatment group for each repeat.

PARTICIPANTS/MATERIALS, SETTING, METHODS

Reproductive performance of female mice was determined by litter size, ovarian follicles and oocyte quantity and quality, and compared with age-matched controls. The impact of resveratrol on telomeres and telomerase activity, and expression of genes associated with cell senescence also was evaluated.

MAIN RESULTS AND THE ROLE OF CHANCE

Young mice fed with resveratrol for 12 months retained the capacity to reproduce, while age-matched controls produced no pups. Consistently, mice fed with resveratrol for 12 months exhibited a larger follicle pool than controls (P < 0.05). Furthermore, telomerase activity, telomere length and age-related gene expression in ovaries of mice fed with resveratrol resembled those of young mice, but differed (P < 0.05) from those of age-matched old mice. Resveratrol improved (P < 0.05) the number and quality of oocytes, as evidenced by spindle morphology and chromosome alignment. Also, resveratrol affected embryo development in vitro in a dose-dependent manner.

LIMITATIONS, REASONS FOR CAUTION

The doses of resveratrol and the experimental conditions used by different research groups have varied considerably, and the dosage influences both the effectiveness and toxicity of resveratrol. Fine-tuning the dosage of resveratrol likely will optimize its anti-aging effects on ovarian function.

WIDER IMPLICATIONS OF THE FINDINGS

Our data provide a proof of principle of the fertility-sparing effect of resveratrol in female mice. Although depletion of the ovarian reserve of high-quality oocytes also contributes to increased infertility with reproductive aging in women, the data obtained using a mouse model may not extrapolate directly to human reproduction, and more extensive research is needed if any clinic trials are to be attempted.

STUDY FUNDING/COMPETING INTEREST(S)

This work was supported by MOST of China National Basic Research Program (grant number: 2010CB94500 and 2012CB911200). The authors have no competing interests to declare.

Loss of cardioprotection with ischemic preconditioning in aging hearts: role of sirtuin 1?

The effectiveness of ischemic preconditioning (IPC) to protect the heart against ischemia/reperfusion injury (IRI) declines with age. The deacetylase protein sirtuin 1 (Sirt 1) confers myriad functions including longevity and cardioprotection against IRI. As such, Sirt 1 may be a potential candidate to explain the protective effect of IPC. We aim to explore the role of Sirt 1 in the loss of the cardioprotective effect of IPC with age. Isolated hearts from young (9 weeks) and older (12-18 months) Long-Evans rats were subjected to 30 minutes of global ischemia and 60 minutes of reperfusion. Preconditioning stimuli were applied with either 2 cycles of 5-minute ischemia/reperfusion or with the potent Sirt 1 agonist resveratrol (RSV, 10 µmol/L) for 15 minutes followed by a 10-minute washout before the sustained ischemia. Both IPC and RSV significantly enhanced the functional recovery of young hearts by 168% (P < .001 vs control) and 65% (P < .01 vs control), respectively, and concomitantly reduced the infarct size by 65% and 45%, but the effect was blunted in older hearts. Administration of the selective Sirt 1 inhibitor III to young hearts did not alter the protective effect of IPC. Following ischemia/reperfusion, higher Sirt 1 deacetylase activity was detected in older hearts compared to young hearts (0.48 ± 0.13 arbitrary units [AU] vs 0.17 ± 0.03 AU, P < .01) and IPC did not alter Sirt 1 deacetylase activity. In conclusion, although Sirt 1 deacetylase activity is increased with age during ischemia/reperfusion, our data suggest that the loss of the cardioprotective effect of IPC in older animals is likely to be independent of Sirt 1.