Comparing and contrasting the roles of AMPK and SIRT1 in metabolic tissues

P7C3 ameliorates barium chloride-induced skeletal muscle injury activating transcriptomic and epigenetic modulation of myogenic regulatory factors

Skeletal muscle injury affects the quality of life in many pathologies, including volumetric muscle loss, contusion injury, and aging. We hypothesized that the nicotinamide phosphoribosyltransferase (Nampt) activator P7C3 improves muscle repair following injury. In the present study, we tested the effect of P7C3 (1-anilino-3-(3,6-dibromocarbazol-9-yl) propan-2-ol) on chemically induced muscle injury. Muscle injury was induced by injecting 50 µL 1.2% barium chloride (BaCl2) into the tibialis anterior (TA) muscle in C57Bl/6J wild-type male mice. Mice were then treated with either 10 mg/kg body weight of P7C3 or Vehicle intraperitoneally for 7 days and assessed for histological, biochemical, and molecular changes. In the present study, we show that the acute BaCl2-induced TA muscle injury was robust and the P7C3-treated mice displayed a significant increase in the total number of myonuclei and blood vessels, and decreased serum CK activity compared with vehicle-treated mice. The specificity of P7C3 was evaluated using Nampt+/- mice, which did not display any significant difference in muscle repair capacity among treated groups. RNA-sequencing analysis of the injured TA muscles displayed 368 and 212 genes to be exclusively expressed in P7C3 and Veh-treated mice, respectively. There was an increase in the expression of genes involved in cellular processes, inflammatory response, angiogenesis, and muscle development in P7C3 versus Veh-treated mice. Conversely, there is a decrease in muscle structure and function, myeloid cell differentiation, glutathione, and oxidation-reduction, drug metabolism, and circadian rhythm signaling pathways. Chromatin immunoprecipitation-quantitative polymerase chain reaction (qPCR) and reverse transcription-qPCR analyses identified increased Pax7, Myf5, MyoD, and Myogenin expression in P7C3-treated mice. Increased histone lysine (H3K) methylation and acetylation were observed in P7C3-treated mice, with significant upregulation in inflammatory markers. Moreover, P7C3 treatment significantly increased the myotube fusion index in the BaCl2-injured human skeletal muscle in vitro. P7C3 also inhibited the lipopolysaccharide-induced inflammatory response and mitochondrial membrane potential of RAW 264.7 macrophage cells. Overall, we demonstrate that P7C3 activates muscle stem cells and enhances muscle injury repair with increased angiogenesis.

AMPK activation reduces cancer cell aggressiveness via inhibition of monoamine oxidase A (MAO-A) expression/activity

AIM

AMPK can be considered as an important target molecule for cancer for its unique ability to directly recognize cellular energy status. The main aim of this study is to explore the role of different AMPK activators in managing cancer cell aggressiveness and to understand the mechanistic details behind the process.

MAIN METHODS

First, we explored the AMPK expression pattern and its significance in different subtypes of lung cancer by accessing the TCGA data sets for LUNG, LUAD and LUSC patients and then established the correlation between AMPK expression pattern and overall survival of lung cancer patients using Kaplan-Meire plot. We further carried out several cell-based assays by employing different wet lab techniques including RT-PCR, Western Blot, proliferation, migration and invasion assays to fulfil the aim of the study.

KEY FINDINGS

SIGNIFICANCE: This study identifies the importance of AMPK activators as a repurposing agent for combating lung and colon cancer cell aggressiveness. It also suggests SRT-1720 as a potent repurposing agent for cancer treatment especially in NSCLC patients where a point mutation is present in LKB1.

Exploring the Potential of Ribes nigrum L., Aronia melanocarpa (Michx.) Elliott, and Sambucus nigra L. Fruit Polyphenol-Rich Composition and Metformin Synergy in Type 2 Diabetes Management

Type 2 diabetes, characterized by insulin resistance and impaired glucose homeostasis, is commonly managed through lifestyle interventions and medications such as metformin. Although metformin is generally well-tolerated, it may cause gastrointestinal adverse effects and, in rare cases, precipitate lactic acidosis, necessitating cautious use in individuals with renal dysfunction. Additionally, concerns regarding its impact on hepatic function have led to its discontinuation in cirrhotic patients. This study explores the potential synergistic benefits of a polyphenol-rich blend containing black currant, chokeberry, and black elderberry extracts alongside metformin in managing type 2 diabetes. In vitro results highlighted distinct effects of AMPK pathway modulation, showcasing reductions in cholesterol and triglyceride levels alongside a notable enhancement in glucose uptake. The blend, when combined with metformin, significantly reduced insulin levels and fasting glucose concentrations in an in vivo model. Furthermore, hepatic analyses unveiled a modulation in cellular pathways, suggesting a potential influence on lipid metabolism, attenuation of inflammatory pathways, a decrease in cellular stress response, and antioxidant defense mechanisms, collectively implying a potential reduction in liver fat accumulation. The findings suggest a potential complementary role of polyphenols in enhancing the efficacy of metformin, possibly allowing for reduced metformin dosage and mitigating its side effects. Further clinical studies are warranted to validate these findings and establish the safety and efficacy of this nutraceutical approach in managing type 2 diabetes.

Glucosyltriazole amphiphile treatment attenuates breast cancer by modulating the AMPK signaling

Breast cancer is the second most frequent cancer among women. Out of various subtypes, triple-negative breast cancers (TNBCs) account for 15% of breast cancers and exhibit more aggressive characteristics as well as a worse prognosis due to their proclivity for metastatic progression and limited therapeutic strategies. It has been demonstrated that AMP-activated protein kinase (AMPK) has context-specific protumorigenic implications in breast cancer cells. A set of glucosyltriazole amphiphiles, consisting of acetylated (9a-h) and unmodified sugar hydroxyl groups (10a-h), were synthesized and subjected to in vitro biological evaluation. Among them, 9h exhibited significant anticancer activity against MDA-MB-231, MCF-7, and 4T1 cell lines with IC50 values of 12.5, 15, and 12.55 μM, respectively. Further, compound 9h was evaluated for apoptosis and cell cycle analysis in in vitro models (using breast cancer cells) and antitumour activity in an in vivo model (orthotopic mouse model using 4T1 cells). Annexin-V assay results revealed that treatment with 9h caused 34% and 28% cell death at a concentration of 15 or 7.5 μM, respectively, while cell cycle analysis demonstrated that 9h arrested the cells at the G2/M or G1 phase in MCF-7, MDA-MB-231 and 4T1 cells, respectively. Further, in vivo, investigation showed that compound 9h exhibited equipotent as doxorubicin at 7.5 mg/kg, and superior efficacy than doxorubicin at 15 mg/kg. The mechanistic approach revealed that 9h showed potent anticancer activity in an in vivo orthotopic model (4T1 cells) partly by suppressing the AMPK activation. Therefore, modulating the AMPK activation could be a probable approach for targeting breast cancer and mitigating cancer progression.

Combined Aerobic Exercise with Intermittent Fasting Is Effective for Reducing mTOR and Bcl-2 Levels in Obese Females

The integration of combined aerobic exercise and intermittent fasting (IF) has emerged as a strategy for the prevention and management of obesity, including its associated health issues such as age-related metabolic diseases. This study aimed to examine the potential of combined aerobic exercise and IF as a preventative strategy against cellular senescence by targeting mTOR and Bcl-2 levels in obese females. A total of 30 obese women, aged 23.56 ± 1.83 years, body fat percentage (FAT) 45.21 ± 3.73% (very high category), BMI 30.09 ± 3.74 kg/m2 were recruited and participated in three different types of interventions: intermittent fasting (IF), exercise (EXG), and a combination of intermittent fasting and exercise (IFEXG). The intervention program was carried out 5x/week for 2 weeks. We examined mTOR and Bcl-2 levels using ELISA kits. Statistical analysis used the one-way ANOVA test and continued with Tukey's HSD post hoc test, with a significance level of 5%. The study results showed that a combination of aerobic exercise and IF significantly decreased mTOR levels (-1.26 ± 0.79 ng/mL) compared to the control group (-0.08 ± 1.33 ng/mL; p ≤ 0.05). However, combined aerobic exercise and IF did not affect Bcl-2 levels significantly (-0.07 ± 0.09 ng/mL) compared to the control group (0.01 ± 0.17 ng/mL, p ≥ 0.05). The IF-only group, exercise-only group, and combined group all showed a significant decrease in body weight and fat mass compared to the control group (p ≤ 0.05). However, the combined aerobic exercise and IF program had a significant effect in reducing the total percentage of body fat and fat mass compared to the IF-only group (p ≤ 0.05). Therefore, it was concluded that the combined intermittent fasting and exercise group (IFEXG) undertook the most effective intervention of the three in terms of preventing cellular senescence, as demonstrated by decreases in the mTOR level, body weight, and fat mass. However, the IFEXG did not present reduced Bcl-2 levels.

Aging in Ocular Blood Vessels: Molecular Insights and the Role of Oxidative Stress

Acknowledged as a significant pathogenetic driver for numerous diseases, aging has become a focal point in addressing the profound changes associated with increasing human life expectancy, posing a critical concern for global public health. Emerging evidence suggests that factors influencing vascular aging extend their impact to choroidal and retinal blood vessels. The objective of this work is to provide a comprehensive overview of the impact of vascular aging on ocular blood vessels and related diseases. Additionally, this study aims to illuminate molecular insights contributing to vascular cell aging, with a particular emphasis on the choroid and retina. Moreover, innovative molecular targets operating within the domain of ocular vascular aging are presented and discussed.

Trehalose-induced SIRT1/AMPK activation regulates SREBP-1c/PPAR-α to alleviate lipid accumulation in aged liver

Aging is associated with a disturbance in the regulation of the metabolic function of the liver, which increases the risk of liver and systemic diseases. Trehalose, a natural disaccharide, has been identified to reduce dyslipidemia, hepatic steatosis, and glucose intolerance. However, the roles of trehalose on lipid metabolism in aged liver are unclear which was investigated in this study. Thirty-two male Wistar rats were randomly allocated into four groups (n = 8). Two groups of aged (24 months) and young (4 months) rats were administered 2% trehalose solution orally for 30 days. Control groups of aged and young rats did not receive any treatment. At the end of the treatment period, blood samples and liver tissues were collected. Then the expression of SIRT1, AMPK, SREBP-1c, and PPAR-α and the level of AMPK phosphorylation (p-AMPK) were quantified by real-time polymerase chain reaction and western blotting. Moreover, biochemical parameters and the histopathology of livers were evaluated. Trehalose supplementation increased the level of SIRT1, p-AMPK, and PPAR-α, whereas the level of SREBP-1c was diminished in the liver of old animals. In addition, treatment with trehalose improved histopathological features of senescent livers. Taken together, our results show that old rats developed lipogenesis in the liver which was alleviated with trehalose. Therefore, trehalose may be an effective intervention to reduce the progression of aging-induced liver diseases.

Milk fat globule size: Unraveling the intricate relationship between metabolism, homeostasis, and stress signaling

Fat is an important component of milk which delivers energy, nutrients, and bioactive molecules from the lactating mother to the suckling neonate. Milk fat consists of a complex mixture of different types of lipids; hundreds of fatty acids, triglycerides, phospholipids, sphingolipids, cholesterol and cholesteryl ester, and glycoconjugates, secreted by the mammary gland epithelial cells (MEC) in the form of a lipid-protein assembly termed the milk fat globule (MFG). The mammary gland in general, and specifically that of modern dairy cows, faces metabolic stress once lactation commences, which changes the lipogenic capacity of MECs directly by reducing available energy and reducing factors required for both lipid synthesis and secretion or indirectly by activating a proinflammatory response. Both processes have the capacity to change the morphometric features (e.g., number and size) of the secreted MFG and its precursor-the intracellular lipid droplet (LD). The MFG size is tightly associated with its lipidome and proteome and also affects the bioavailability of milk fat and protein. Thus, MFG size has the potential to regulate the bioactivity of milk and dairy products. MFG size also plays a central role in the functional properties of milk and dairy products such as texture and stability. To understand how stress affects the structure-function of the MFG, we cover: (i) The mechanism of production and secretion of the MFG and the implications of MFG size, (ii) How the response mechanisms to stress can change the morphometric features of MFGs, and (iii) The possible consequences of such modifications.

Therapeutic potential of melatonin and its derivatives in aging and neurodegenerative diseases

Aging is associated with increasing impairments in brain homeostasis and represents the main risk factor across most neurodegenerative disorders. Melatonin, a neuroendocrine hormone that regulates mammalian chronobiology and endocrine functions is well known for its antioxidant potential, exhibiting both cytoprotective and chronobiotic abilities. Age-related decline of melatonin disrupting mitochondrial homeostasis and cytosolic DNA-mediated inflammatory reactions in neurons is a major contributory factor in the emergence of neurological abnormalities. There is scattered literature on the possible use of melatonin against neurodegenerative mechanisms in the aging process and its associated diseases. We have searched PUBMED with many combinations of key words for available literature spanning two decades. Based on the vast number of experimental papers, we hereby review recent advancements concerning the potential impact of melatonin on cellular redox balance and mitochondrial dynamics in the context of neurodegeneration. Next, we discuss a broader explanation of the involvement of disrupted redox homeostasis in the pathophysiology of age-related diseases and its connection to circadian mechanisms. Our effort may result in the discovery of novel therapeutic approaches. Finally, we summarize the current knowledge on molecular and circadian regulatory mechanisms of melatonin to overcome neurodegenerative diseases (NDDs) such as Alzheimer's, Parkinson's, Huntington's disease, and amyotrophic lateral sclerosis, however, these findings need to be confirmed by larger, well-designed clinical trials. This review is also expected to uncover the associated molecular alterations in the aging brain and explain how melatonin-mediated circadian restoration of neuronal homeodynamics may increase healthy lifespan in age-related NDDs.

Thioredoxin-1 Promotes Mitochondrial Biogenesis Through Regulating AMPK/Sirt1/PGC1α Pathway in Alzheimer's Disease

Alzheimer's disease (AD) is the most common neurodegenerative disease. Increasing studies suggest that mitochondrial dysfunction is closely related to the pathogenesis of AD. Thioredoxin-1 (Trx-1), one of the major redox proteins in mammalian cells, plays neuroprotection in AD. However, whether Trx-1 could regulate the mitochondrial biogenesis in AD is largely unknown. In the present study, we found that Aβ_25-35 treatment not only markedly induced excessive production of reactive oxygen species and apoptosis, but also significantly decreased the number of mitochondria with biological activity and the adenosine triphosphate content in mitochondria, suggesting mitochondrial biogenesis was impaired in AD cells. These changes were reversed by Lentivirus-mediated stable overexpression of Trx-1 or exogenous administration of recombinant human Trx-1. What's more, adeno-associated virus-mediated specific overexpression of Trx-1 in the hippocampus of β-amyloid precursor protein/presenilin 1 (APP/PS1) mice ameliorated the learning and memory and attenuated hippocampal Aβ deposition. Importantly, overexpression of Trx-1 in APP/PS1 mice restored the decrease in mitochondrial biogenesis-associated proteins, including adenosine monophosphate -activated protein kinase (AMPK), silent information regulator factor 2-related enzyme 1 (Sirt1) and peroxisome proliferator-activated receptor gamma coactivator 1-alpha (PGC1α). In addition, Lentivirus-mediated overexpression of Trx-1 in rat adrenal pheochromocytoma (PC12) cells also restored the decrease of AMPK, Sirt1, and PGC1α by Aβ_25-35 treatment. Pharmacological inhibition of AMPK activity significantly abolished the effect of Trx-1 on mitochondrial biogenesis. Taken together, our data provide evidence that Trx-1 promoted mitochondrial biogenesis via restoring AMPK/Sirt1/PGC1α pathway in AD.

Mitochondrial Open Reading Frame of the 12S rRNA Type-c: Potential Therapeutic Candidate in Retinal Diseases

Mitochondrial open reading frame of the 12S rRNA type-c (MOTS-c) is the most unearthed peptide encoded by mitochondrial DNA (mtDNA). It is an important regulator of the nuclear genome during times of stress because it promotes an adaptive stress response to maintain cellular homeostasis. Identifying MOTS-c specific binding partners may aid in deciphering the complex web of mitochondrial and nuclear-encoded signals. Mitochondrial damage and dysfunction have been linked to aging and the accelerated cell death associated with many types of retinal degenerations. Furthermore, research on MOTS-c ability to revive oxidatively stressed RPE cells has revealed a significant protective role for the molecule. Evidence suggests that senescent cells play a role in the development of age-related retinal disorders. This review examines the links between MOTS-c, mitochondria, and age-related diseases of the retina. Moreover, the untapped potential of MOTS-c as a treatment for glaucoma, diabetic retinopathy, and age-related macular degeneration is reviewed.

Depletion of stearoyl-CoA desaturase (scd) leads to fatty liver disease and defective mating behavior in zebrafish

Stearyl coenzyme A desaturase (SCD), also known as delta-9 desaturase, catalyzes the rate-limiting step in the formation of monounsaturated fatty acids. In mammals, depletion or inhibition of SCD activity generally leads to a decrease in triglycerides and cholesteryl esters. However, the endogenous role of scd in teleost fish remains unknown. Here, we generated a zebrafish scd mutant (scd^-/-) to elucidate the role of scd in lipid metabolism and sexual development. Gas chromatography-mass spectrometry (GC-MS) showed that the scd^-/- mutants had increased levels of saturated fatty acids C16:0 and C18:0, and decreased levels of monounsaturated fatty acids C16:1 and C18:1. The mutant fish displayed a short stature and an enlarged abdomen during development. Unlike Scd^-/- mammals, the scd^-/- zebrafish showed significantly increased fat accumulation in the whole body, especially in the liver, leading to hepatic mitochondrial dysfunction and severe cell apoptosis. Mechanistically, srebf1, a gene encoding a transcriptional activator related to adipogenesis, acc1 and acaca, genes involved in fatty acid synthesis, and dgat2, a key gene involved in triglyceride synthesis, were significantly upregulated in mutant livers to activate fatty acid biosynthesis and adipogenesis. The scd^-/- males exhibited defective natural mating behavior due to defective genital papillae but possessed functional mature sperm. All defects in the scd^-/- mutants could be rescued by ubiquitous transgenic overexpression of scd. In conclusion, our study demonstrates that scd is indispensable for maintaining lipid homeostasis and development of secondary sexual characteristics in zebrafish.

Hepatic Steatosis Alleviated by a Novel Metformin and Quercetin Combination Activating Autophagy Through the cAMP/AMPK/SIRT1 Pathway

Non-alcoholic fatty liver disease (NAFLD) incidence and prevalence are rapidly increasing globally. The combined effects of metformin and quercetin (Que) have yet to be investigated. However, both have demonstrated the potential to reduce triglyceride (TG) levels and treat NAFLD by promoting autophagy. The objective of the present study was to elucidate the mechanism of action and assess the role of autophagy in the lipid-lowering effects of Que, both individually and in combination with metformin, in a HepG2 cell model of hepatic steatosis. Triglyceride levels and lipogenic gene expression were reduced in HepG2 cells exposed to palmitic acid (PA) when treated with Que-metformin, as evidenced by triglyceride measurements and real-time PCR. The LDH release assay also showed that this combination induced autophagy to protect HepG2 cells from PA-induced cell death. According to the Western blot analysis outcomes, Que-metformin increased LC3-I and LC3-II protein levels while decreasing p62 expression to induce autophagy. In HepG2 cells, the co-administration of Que-metformin elevated cAMP, phosphorylated AMP-activated protein kinase (p-AMPK), and Beclin-1 levels. Additionally, the inhibition of SIRT1 reversed the autophagy induced by Que-metformin. The findings of this study demonstrated for the first time that Que-metformin reduced hepatosteatosis by stimulating autophagy through the cAMP/AMPK/SIRT1 signaling pathway and diminishing inflammatory cytokines.

An Altered Neurovascular System in Aging-Related Eye Diseases

The eye has a complex and metabolically active neurovascular system. Repeated light injuries induce aging and trigger age-dependent eye diseases. Damage to blood vessels is related to the disruption of the blood-retinal barrier (BRB), altered cellular communication, disrupted mitochondrial functions, and exacerbated aggregated protein accumulation. Vascular complications, such as insufficient blood supply and BRB disruption, have been suggested to play a role in glaucoma, age-related macular degeneration (AMD), and Alzheimer's disease (AD), resulting in neuronal cell death. Neuronal loss can induce vision loss. In this review, we discuss the importance of the neurovascular system in the eye, especially in aging-related diseases such as glaucoma, AMD, and AD. Beneficial molecular pathways to prevent or slow down retinal pathologic processes will also be discussed.

Current and future approaches for in vitro hit discovery in diabetes mellitus

Type 2 diabetes mellitus (T2DM) is a serious public health problem. In this review, we discuss current and promising future drugs, targets, in vitro assays and emerging omics technologies in T2DM. Importantly, we open the perspective to image-based high-content screening (HCS), with the focus of combining it with metabolomics or lipidomics. HCS has become a strong technology in phenotypic screens because it allows comprehensive screening for the cell-modulatory activity of small molecules. Metabolomics and lipidomics screen for perturbations at the molecular level. The combination of these data-intensive comprehensive technologies is enabled by the rapid development of artificial intelligence. It promises a deep cellular and molecular phenotyping directly linked to chemical information about the applied drug candidates or complex mixtures.

Reprogramming neurons for regeneration: The fountain of youth

Neurons in the central nervous system (CNS) are terminally differentiated cells that gradually lose their ability to support regeneration during maturation due to changes in transcriptomic and chromatin landscape. Similar transcriptomic changes also occur during development when stem cells differentiate into different types of somatic cells. Importantly, differentiated cells can be reprogrammed back to induced pluripotent stems cells (iPSCs) via global epigenetic remodeling by combined overexpression of pluripotent reprogramming factors, including Oct4, Sox2, Klf4, c-Myc, Nanog, and/or Lin28. Moreover, recent findings showed that many proneural transcription factors were able to convert non-neural somatic cells into neurons bypassing the pluripotent stage via direct reprogramming. Interestingly, many of these factors have recently been identified as key regulators of CNS neural regeneration. Recent studies indicated that these factors could rejuvenate mature CNS neurons back to a younger state through cellular state reprogramming, thus favoring regeneration. Here we will review some recent findings regarding the roles of genetic cellular state reprogramming in regulation of neural regeneration and explore the potential underlying molecular mechanisms. Moreover, by using newly emerging techniques, such as multiomics sequencing with big data analysis and Crispr-based gene editing, we will discuss future research directions focusing on better revealing cellular state reprogramming-induced remodeling of chromatin landscape and potential translational application.

Multi-Omics Integration Analysis Identifies Lipid Disorder of a Non-Alcoholic Fatty Liver Disease (NAFLD) Mouse Model Improved by Zexie–Baizhu Decoction

Non-alcoholic fatty liver disease (NAFLD) is an increasingly epidemic metabolic disease with complex pathogenesis. Multi-target therapy may be an effective strategy for NAFLD treatment, and traditional Chinese medicine (TCM) characterized by multi-ingredients and multi-targets has unique advantages in long-term clinical practice. Zexie–Baizhu (ZXBZ) decoction is a Chinese classical formula to treat body fluid disorders initially. Although many bioactive monomers from Zexie and Baizhu had been discovered to improve lipid disorders, limited research studies were focused on the aqueous decoction of ZXBZ, the original clinical formulation. In the current study, we identified 94% chemical composition of ZXBZ decoction and first discovered its hepaprotective effect in a gubra-amylin NASH (GAN) diet-induced NAFLD mouse model. Based on metabolomics and transcriptomics analyses, we speculated that lipid and glucose metabolisms might be regulated by ZXBZ decoction, which was further confirmed by improved dyslipidemia and hepatic steatosis in ZXBZ groups. Consistently with cross-omics analysis, we discovered ZXBZ decoction could influence two energy sensors, Sirt1 and AMPK, and subsequently affect related proteins involved in lipid biosynthesis, catabolism, and transport. In conclusion, ZXBZ decoction regulated energy sensors, consequently impeded lipogenesis, and promoted fatty acid oxidation (FAO) to alleviate lipid disorders and protect the liver in NAFLD models, which suggested ZXBZ decoction might be a promising treatment for NAFLD.

A Comprehensive Overview of the Complex Role of Oxidative Stress in Aging, The Contributing Environmental Stressors and Emerging Antioxidant Therapeutic Interventions

Introduction

Aging is a normal, inevitable, irreversible, and progressive process which is driven by internal and external factors. Oxidative stress, that is the imbalance between prooxidant and antioxidant molecules favoring the first, plays a key role in the pathophysiology of aging and comprises one of the molecular mechanisms underlying age-related diseases. However, the oxidative stress theory of aging has not been successfully proven in all animal models studying lifespan, meaning that altering oxidative stress/antioxidant defense systems did not always lead to a prolonged lifespan, as expected. On the other hand, animal models of age-related pathological phenotypes showed a well-correlated relationship with the levels of prooxidant molecules. Therefore, it seems that oxidative stress plays a more complicated role than the one once believed and this role might be affected by the environment of each organism. Environmental factors such as UV radiation, air pollution, and an unbalanced diet, have also been implicated in the pathophysiology of aging and seem to initiate this process more rapidly and even at younger ages.

Aim

The purpose of this review is to elucidate the role of oxidative stress in the physiology of aging and the effect of certain environmental factors in initiating and sustaining this process. Understanding the pathophysiology of aging will contribute to the development of strategies to postpone this phenomenon. In addition, recent studies investigating ways to alter the antioxidant defense mechanisms in order to prevent aging will be presented.

Conclusions

Careful exposure to harmful environmental factors and the use of antioxidant supplements could potentially affect the biological processes driving aging and slow down the development of age-related diseases. Maybe a prolonged lifespan could not be achieved by this strategy alone, but a longer healthspan could also be a favorable target.

Sirt6 reprograms myofibers to oxidative type through CREB-dependent Sox6 suppression

Expanding the exercise capacity of skeletal muscle is an emerging strategy to combat obesity-related metabolic diseases and this can be achieved by shifting skeletal muscle fibers toward slow-twitch oxidative type. Here, we report that Sirt6, an anti-aging histone deacetylase, is critical in regulating myofiber configuration toward oxidative type and that Sirt6 activator can be an exercise mimetic. Genetic inactivation of Sirt6 in skeletal muscle reduced while its transgenic overexpression increased mitochondrial oxidative capacity and exercise performance in mice. Mechanistically, we show that Sirt6 downregulated Sox6, a key repressor of slow fiber specific gene, by increasing the transcription of CREB. Sirt6 expression is elevated in chronically exercised humans, and mice treated with an activator of Sirt6 showed an increase in exercise endurance as compared to exercise-trained controls. Thus, the current study identifies Sirt6 as a molecular target for reprogramming myofiber composition toward the oxidative type and for improving muscle performance.

SESN1 attenuates the Ox‑LDL‑induced inflammation, apoptosis and endothelial‑mesenchymal transition of human umbilical vein endothelial cells by regulating AMPK/SIRT1/LOX1 signaling

Endothelial cells are an important component of the heart and vasculature and form a crucial link between the cardiovascular system and the immune system. Sestrin 1 (SESN1) has an important role in atherosclerosis by inhibiting NOD-like receptor family pyrin domain containing 3 inflammasome activation. However, whether SESN1 is involved in human umbilical vein endothelial cell (HUVEC) injury caused by atherosclerosis has remained to be elucidated. The present study aimed to investigate the functions of SESN1 in the inflammatory response, apoptosis and endothelial-mesenchymal transition (EndMT) of HUVECs following stimulation with oxidized low-density lipoprotein (Ox-LDL). SESN1 expression at the mRNA and protein levels was detected using reverse transcription-quantitative PCR (RT-qPCR) and western blot analysis. Following SESN1 overexpression in Ox-LDL-stimulated HUVECs, cell viability was determined using a Cell Counting Kit-8 assay. Terminal deoxynucleotidyl transferase-mediated nick-end labeling staining was employed to detect cell apoptosis and western blot analysis was used to determine the levels of apoptosis-related proteins. RT-qPCR, ELISA and western blot were utilized to determine the levels of inflammatory factors. Immunofluorescence staining, RT-qPCR and western blot analysis were employed to assess the EndMT of Ox-LDL-stimulated HUVECs. The results revealed that SESN1 exhibited a low expression in HUVECs following Ox-LDL stimulation. SESN1 overexpression suppressed inflammation, apoptosis and EndMT in Ox-LDL-induced HUVECs. In addition, SESN1 stimulated adenosine monophosphate-activated protein kinase catalytic subunit α1/sirtuin 1 signaling to suppress Ox-LDL receptor-1 expression. An AMPK and SIRT1 inhibitor reversed the effects of SESN1 overexpression on the inflammatory response, apoptosis and EndMT of HUVECs exposed to Ox-LDL. Taken together, the present study demonstrated that SENS1 exerts a suppressive effect on Ox-LDL-induced inflammation, apoptosis and EndMT of HUVECs, suggesting that SENS1 may be used as a novel biomarker for endothelial injury-related disorders.

Effects of the Water Extract of Fermented Rice Bran on Liver Damage and Intestinal Injury in Aged Rats with High-Fat Diet Feeding

The purpose of this study was to investigate the protective effects of the water extract of fermented rice bran (FRB) on liver damage and intestinal injury in old rats fed a high-fat (HF) diet. Rice bran (RB) was fermented with Aspergillus kawachii, and FRB was produced based on a previous study. Male Sprague Dawley rats at 36 weeks of age were allowed free access to a standard rodent diet and water for 8 weeks of acclimation then randomly divided into four groups (six rats/group), including a normal control (NC) group (normal diet), HF group (HF diet; 60% of total calories from fat), HF + 1% FRB group (HF diet + 1% FRB w/w), and HF + 5% FRB group (HF diet + 5% FRB w/w). It was found that the antioxidant ability of FRB was significantly increased when compared to RB. After 8 weeks of feeding, the HF group exhibited liver damage including an increased non-alcoholic fatty liver disease score (hepatic steatosis and inflammation) and higher interleukin (IL)-1β levels, while these were attenuated in the FRB-treated groups. Elevated plasma leptin levels were also found in the HF group, but the level was down-regulated by FRB treatment. An altered gut microbiotic composition was observed in the HF group, while beneficial bacteria including of the Lactobacillaceae and Lachnospiraceae had increased after FRB supplementation. In conclusion, it was found that FRB had higher anti-oxidative ability and showed the potential for preventing liver damage induced by a HF diet, which might be achieved through regulating imbalanced adipokines and maintaining a healthier microbiotic composition.

Chronic exposure to nonylphenol induces oxidative stress and liver damage in male zebrafish (Danio rerio): Mechanistic insight into cellular energy sensors, lipid accumulation and immune modulation

Nonylphenol (NP), an environmentally persistent and toxic endocrine-disrupting chemical with estrogenic properties, has severe implications on humans and wildlife. Accumulating evidence demonstrates the toxic response of NP on the developmental process, nervous system, and reproductive parameters. Although NP exposure has been implicated in chronic liver injury, the underlying events associated with hepatic pathophysiology remain less investigated. Using male zebrafish (Danio rerio) as the model, the present study investigates the impact of environmentally relevant concentrations of NP (50 and 100 μg/L, 21 days) on hepatic redox homeostasis vis-à-vis cellular energy sensors, inflammatory response, and cell death involving a mechanistic insight into estrogen receptor (ER) modulation. Our results demonstrate that congruent with significant alteration in transcript abundance of antioxidant enzymes (SOD1, SOD2, Catalase, GPx1a, GSTα1), chronic exposure to NP promotes ROS synthesis, more specifically superoxide anions and H₂O₂ levels, and lipid peroxidation potentially through elevated NOX4 expression. Importantly, NP perturbation of markers associated with fatty acid biosynthesis (srebf1/fasn) and cellular energy-sensing network (sirt1/ampkα/pgc1α) indicates dysregulated energy homeostasis, metabolic disruption, and macrovesicular steatosis, albeit with differential sensitivity at the dose level tested. Besides, elevated p38-MAPK phosphorylation (activation) together with loss of ER homeostasis at both mRNA (esr1, esr2a, esr2b) and protein (ERα, ERβ) levels suggest that NP modulation of ER abundance may have a significant influence on hepatic events. Elevated expression of inflammatory markers (TLR4, p-NF-κB, TNF-α, IL-6, IL-1β, and NOS2) and pro-apoptotic and necrotic regulators, e.g., Bax, caspase- 8, -9 and cleaved PARP1 (50 kDa), indicate chronic inflammation and hepatotoxicity in NP-exposed males. Collectively, elevated oxidative stress, metabolic dysregulation and immune modulation may lead to chronic liver injury in organisms exposed to metabolic disrupting chemicals.

Ipragliflozin, an SGLT2 Inhibitor, Ameliorates High-Fat Diet-Induced Metabolic Changes by Upregulating Energy Expenditure through Activation of the AMPK/ SIRT1 Pathway

BACKGROUND

Sodium-glucose co-transporter 2 (SGLT2) inhibitors are a new class of antidiabetic drugs that exhibit multiple extraglycemic effects. However, there are conflicting results regarding the effects of SGLT2 inhibition on energy expenditure and thermogenesis. Therefore, we investigated the effect of ipragliflozin (a selective SGLT2 inhibitor) on energy metabolism.

METHODS

Six-week-old male 129S6/Sv mice with a high propensity for adipose tissue browning were randomly assigned to three groups: normal chow control, 60% high-fat diet (HFD)-fed control, and 60% HFD-fed ipragliflozin-treated groups. The administration of diet and medication was continued for 16 weeks.

RESULTS

The HFD-fed mice became obese and developed hepatic steatosis and adipose tissue hypertrophy, but their random glucose levels were within the normal ranges; these features are similar to the metabolic features of a prediabetic condition. Ipragliflozin treatment markedly attenuated HFD-induced hepatic steatosis and reduced the size of hypertrophied adipocytes to that of smaller adipocytes. In the ipragliflozin treatment group, uncoupling protein 1 (Ucp1) and other thermogenesis-related genes were significantly upregulated in the visceral and subcutaneous adipose tissue, and fatty acid oxidation was increased in the brown adipose tissue. These effects were associated with a significant reduction in the insulin-to-glucagon ratio and the activation of the AMP-activated protein kinase (AMPK)/sirtuin 1 (SIRT1) pathway in the liver and adipose tissue.

CONCLUSION

SGLT2 inhibition by ipragliflozin showed beneficial metabolic effects in 129S6/Sv mice with HFD-induced obesity that mimics prediabetic conditions. Our data suggest that SGLT2 inhibitors, through their upregulation of energy expenditure, may have therapeutic potential in prediabetic obesity.

Autophagy in ovary and polycystic ovary syndrome: role, dispute and future perspective

Polycystic ovary syndrome (PCOS) is a unification of endocrine and metabolic disorders and has become immensely prevalent among women of fertile age. The prime organ affected in PCOS is the ovary and its distressed functioning elicits disturbed reproductive outcomes. In the ovary, macroautophagy/autophagy performs a pivotal role in directing the chain of events starting from oocytes origin until its fertilization. Recent discoveries demonstrate a significant role of autophagy in the pathogenesis of PCOS. Defective autophagy in the follicular cells during different stages of follicles is observed in the PCOS ovary. Exploring different autophagy pathways provides a platform for predicting the possible cause of altered ovarian physiology in PCOS. In this review, we have emphasized autophagy's role in governing follicular development under normal circumstances and in PCOS, including significant abnormalities associated with PCOS such as anovulation, hyperandrogenemia, metabolic disturbances, and related abnormality. So far, few studies have linked autophagy and PCOS and propose its essential role in PCOS progression. However, detailed knowledge in this area is lacking. Here we have summarized the latest knowledge related to autophagy associated with PCOS. This review's main objective is to provide a background of autophagy in the ovary, its possible connection with PCOS and suggested a novel proposal for future studies to aid a better understanding of PCOS pathogenesis.Abbreviations: AE: androgen excess; AF: antral follicle; AKT/PKB: AKT serine/threonine kinase; AMH: anti-Mullerian hormone; AMPK: AMP-activated protein kinase; ATG: autophagy-related; BCL2: BCL2 apoptosis regulator; BECN1: beclin 1; BMP: bone morphogenetic protein; CASP3: caspase 3; CL: corpus luteum; CYP17A1/P450C17: cytochrome P450 family 17 subfamily A member 1; CYP19A1: cytochrome P450 family 19 subfamily A member 1; DHEA: dehydroepiandrosterone; EH: endometrial hyperplasia; FF: follicular fluid; FOXO: forkhead box O; FSH: follicle stimulating hormone; GC: granulosa cell; GDF: growth differentiation factor; HA: hyperandrogenemia; HMGB1: high mobility group box 1; IGF1: insulin like growth factor 1; INS: insulin; IR: insulin resistance; LHCGR/LHR: luteinizing hormone/choriogonadotropin receptor; MAP1LC3B/LC3B: microtubule associated protein 1 light chain 3 beta; MAPK/ERK: mitogen-activated protein kinase; MAPK8/JNK: mitogen-activated protein kinase 8; MTOR: mechanistic target of rapamycin kinase; MTORC: mechanistic target of rapamycin complex; NAFLD: nonalcoholic fatty liver disease; NFKB: nuclear factor kappa B; OLR1/LOX-1: oxidized low density lipoprotein receptor 1; oxLDL: oxidized low-density lipoproteins; PA: palmitic acid; PCOS: polycystic ovary syndrome; PF: primary follicle; PGC: primordial germ cell; PI3K: phosphoinositide 3-kinase; PMF: primordial follicle; ROS: reactive oxygen species; RP: resting pool; SIRT1: sirtuin 1; SQSTM1/p62: sequestosome 1; T2DM: type 2 diabetes mellitus; TC: theca cell; TUG1: taurine up-regulated 1.

Mitochondrial Biogenesis, Mitochondrial Dynamics, and Mitophagy in the Maturation of Cardiomyocytes

Pluripotent stem cells (PSCs) can undergo unlimited self-renewal and can differentiate into all the cell types present in our body, including cardiomyocytes. Therefore, PSCs can be an excellent source of cardiomyocytes for future regenerative medicine and medical research studies. However, cardiomyocytes obtained from PSC differentiation culture are regarded as immature structurally, electrophysiologically, metabolically, and functionally. Mitochondria are organelles responsible for various cellular functions such as energy metabolism, different catabolic and anabolic processes, calcium fluxes, and various signaling pathways. Cells can respond to cellular needs to increase the mitochondrial mass by mitochondrial biogenesis. On the other hand, cells can also degrade mitochondria through mitophagy. Mitochondria are also dynamic organelles that undergo continuous fusion and fission events. In this review, we aim to summarize previous findings on the changes of mitochondrial biogenesis, mitophagy, and mitochondrial dynamics during the maturation of cardiomyocytes. In addition, we intend to summarize whether changes in these processes would affect the maturation of cardiomyocytes. Lastly, we aim to discuss unanswered questions in the field and to provide insights for the possible strategies of enhancing the maturation of PSC-derived cardiomyocytes.

Perfluorooctanesulfonic Acid (PFOS) Thwarts the Beneficial Effects of Calorie Restriction and Metformin

A combination of calorie restriction (CR), dietary modification, and exercise is the recommended therapy to reverse obesity and nonalcoholic fatty liver disease. In the liver, CR shifts hepatic metabolism from lipid storage to lipid utilization pathways, such as AMP-activated protein kinase (AMPK). Perfluorooctanesulfonic acid (PFOS), a fluorosurfactant previously used in stain repellents and anti-stick materials, can increase hepatic lipids in mice following relatively low-dose exposures. To test the hypothesis that PFOS administration interferes with CR, adult male C57BL/6N mice were fed ad libitum or a 25% reduced calorie diet concomitant with either vehicle (water) or 100 μg PFOS/kg/day via oral gavage for 6 weeks. CR alone improved hepatic lipids and glucose tolerance. PFOS did not significantly alter CR-induced weight loss, white adipose tissue mass, or liver weight over 6 weeks. However, PFOS increased hepatic triglyceride accumulation, in both mice fed ad libitum and subjected to CR. This was associated with decreased phosphorylated AMPK expression in liver. Glucagon (100 nM) treatment induced glucose production in hepatocytes, which was further upregulated with PFOS (2.5 μM) co-treatment. Next, to explore whether the observed changes were related to AMPK signaling, HepG2 cells were treated with metformin or AICAR alone or in combination with PFOS (25 μM). PFOS interfered with glucose-lowering effects of metformin, and AICAR treatment partially impaired PFOS-induced increase in glucose production. In 3T3-L1 adipocytes, metformin was less effective with PFOS co-treatment. Overall, PFOS administration disrupted hepatic lipid and glucose homeostasis and interfered with beneficial glucose-lowering effects of CR and metformin.

Targeting Mitochondrial Biogenesis with Polyphenol Compounds

Appropriate mitochondrial physiology is an essential for health and survival. Cells have developed unique mechanisms to adapt to stress circumstances and changes in metabolic demands, by meditating mitochondrial function and number. In this context, sufficient mitochondrial biogenesis is necessary for efficient cell function and haemostasis, which is dependent on the regulation of ATP generation and maintenance of mitochondrial DNA (mtDNA). These procedures play a primary role in the processes of inflammation, aging, cancer, metabolic diseases, and neurodegeneration. Polyphenols have been considered as the main components of plants, fruits, and natural extracts with proven therapeutic effects during the time. These components regulate the intracellular pathways of mitochondrial biogenesis. Therefore, the current review is aimed at representing an updated review which determines the effects of different natural polyphenol compounds from various plant kingdoms on modulating signaling pathways of mitochondrial biogenesis that could be a promising alternative for the treatment of several disorders.

Resveratrol-induced Sirt1 phosphorylation by LKB1 mediates mitochondrial metabolism

The NAD⁺-dependent deacetylase Sirt1 has been implicated in the prevention of many age-related diseases, including cancer, type 2 diabetes, and cardiovascular disease. Resveratrol, a plant polyphenol, exhibits antiaging, antitumor, and vascular protection effects by activating Sirt1. However, the molecular mechanism of Sirt1 activation as induced by resveratrol remains unclear. By knockdown/rescue experiments, fluorometric Sirt1 activity assay, immunoprecipitation, and pull-down assays, we identify here that the tumor suppressor LKB1 (liver kinase B1) as a direct activator of Sirt1 elicited by resveratrol. Resveratrol promotes the binding between LKB1 and Sirt1, which we first reported, and this binding leads to LKB1-mediated phosphorylation of Sirt1 at three different serine residues in the C terminus of Sirt1. Mechanistically, LKB1-mediated phosphorylation increases intramolecular interactions in Sirt1, such as the binding of the C terminus to the deacetylase core domain, thereby eliminating DBC1 (Deleted in Breast Cancer 1, Sirt1 endogenous inhibitor) inhibition and promoting Sirt1–substrate interaction. Functionally, LKB1-dependent Sirt1 activation increases mitochondrial biogenesis and respiration through deacetylation and activation of the transcriptional coactivator PGC-1α. These results identify Sirt1 as a context-dependent target of LKB1 and suggest that a resveratrol-stimulated LKB1-Sirt1 pathway plays a vital role in mitochondrial metabolism, a key physiological process that contributes to numerous age-related diseases.

Function and Mechanism of Trimetazidine in Myocardial Infarction-Induced Myocardial Energy Metabolism Disorder Through the SIRT1-AMPK Pathway

Myocardial energy metabolism (MEM) is an important factor of myocardial injury. Trimetazidine (TMZ) provides protection against myocardial ischemia/reperfusion injury. The current study set out to evaluate the effect and mechanism of TMZ on MEM disorder induced by myocardial infarction (MI). Firstly, a MI mouse model was established by coronary artery ligation, which was then treated with different concentrations of TMZ (5, 10, and 20 mg kg^-1 day^-1). The results suggested that TMZ reduced the heart/weight ratio in a concentration-dependent manner. TMZ also reduced the levels of Bax and cleaved caspase-3 and promoted Bcl-2 expression. In addition, TMZ augmented adenosine triphosphate (ATP) production and superoxide dismutase (SOD) activity induced by MI and decreased the levels of lipid peroxide (LPO), free fatty acids (FFA), and nitric oxide (NO) in a concentration-dependent manner (all P < 0.05). Furthermore, an H₂O₂-induced cell injury model was established and treated with different concentrations of TMZ (1, 5, and 10 μM). The results showed that SIRT1 overexpression promoted ATP production and reactive oxygen species (ROS) activity and reduced the levels of LPO, FFA, and NO in H9C2 cardiomyocytes treated with H₂O₂ and TMZ. Silencing SIRT1 suppressed ATP production and ROS activity and increased the levels of LPO, FFA, and NO (all P < 0.05). TMZ activated the SIRT1-AMPK pathway by increasing SIRT1 expression and AMPK phosphorylation. In conclusion, TMZ inhibited MI-induced myocardial apoptosis and MEM disorder by activating the SIRT1-AMPK pathway.

Regulation of Cytochrome c Oxidase by Natural Compounds Resveratrol, (-)-Epicatechin, and Betaine

Numerous naturally occurring molecules have been studied for their beneficial health effects. Many compounds have received considerable attention for their potential medical uses. Among them, several substances have been found to improve mitochondrial function. This review focuses on resveratrol, (–)-epicatechin, and betaine and summarizes the published data pertaining to their effects on cytochrome c oxidase (COX) which is the terminal enzyme of the mitochondrial electron transport chain and is considered to play an important role in the regulation of mitochondrial respiration. In a variety of experimental model systems, these compounds have been shown to improve mitochondrial biogenesis in addition to increased COX amount and/or its enzymatic activity. Given that they are inexpensive, safe in a wide range of concentrations, and effectively improve mitochondrial and COX function, these compounds could be attractive enough for possible therapeutic or health improvement strategies.

Echinacoside improves diabetic liver injury by regulating the AMPK/SIRT1 signaling pathway in db/db mice

AIMS

Echinacoside (ECH) is a natural compound extracted from the stem of the Cistanche deserticola plant, has significant biological properties, including antioxidant, anti-inflammatory, neuroprotective, anti-tumor, hepatoprotective, and immunomodulatory properties. In this study, we aimed to explore the protection effects and mechanisms of ECH on diabetic liver injury in db/db mice.

MAIN METHODS

Overall, 6-week-old db/db mice (n = 20) were randomly allocated to 2 groups: diabetic model group (db/db group, intragastric administration of normal saline, n = 10) and ECH-treated group (db/db + ECH group, n = 10). Additionally, the normal control group comprised 6-week-old db/m mice (db/m group, normal saline intragastric administration, n = 10). ECH was administered once a day for 10 weeks. Weight and fasting blood glucose (FBG) were measured biweekly. HE staining and Oil O staining were used to evaluate liver tissue pathological changes and lipid accumulation respectively. Immunofluorescence staining, Western blot and RT-PCR analysis were used to detect the expression of components of the AMPK/SIRT1 signaling axis.

KEY FINDINGS

The results showed that the administration of echinacoside for 10 weeks could significantly improve liver injury and insulin resistance in db/db mice (p < 0.01). Also, echinacoside treatment helped to reduce blood lipids and blood glucose (p < 0.01). Moreover, ECH actived AMPK/SIRT1 signaling, upregulated peroxisome proliferator-activated receptor gamma co-activator 1 alpha (PGC-1α), proliferator-activated receptor-α (PPARα), carnitine palmitoyl transferase-1A (CPT1A) in db/db mice (p < 0.01).

SIGNIFICANCE

The effect of ECH may be elicited by the activation of the liver AMPK/SIRT1 pathway and its downstream factors to improve adiposity, insulin resistance, and dyslipidemia.

Energy sensors and reproductive hypothalamo-pituitary ovarian axis (HPO) in female mammals: Role of mTOR (mammalian target of rapamycin), AMPK (AMP-activated protein kinase) and SIRT1 (Sirtuin 1)

In female, energy metabolism influences reproductive function by modulating the Hypothalamic Pituitary Ovarian axis including the hypothalamic GnRH neuronal network, the pituitary gonadotropin secretion and the ovarian follicle growth and steroidogenesis. Several hormones and neuropeptides or metabolites are important signals between energy balance and reproduction. These energy sensors mediate their action on reproductive cells through specific kinases or signaling pathways. This review focuses on the role of three main enzymes-specifically, mTOR, AMPK, and SIRT1 at the hypothalamic pituitary and ovarian axis in normal female fertility and then we discuss their possible involvement in some women reproductive disorders known to be associated with metabolic complications, such as polycystic ovary syndrome (PCOS) and premature ovarian failure (POF).

Cell Energy Metabolism and Hyaluronan Synthesis

Hyaluronan (HA) is a linear glycosaminoglycan (GAG) of extracellular matrix (ECM) synthesized by three hyaluronan synthases (HASes) at the plasma membrane using uridine diphosphate (UDP)-glucuronic acid (UDP-GlcUA) and UDP-N-acetylglucosamine (UDP-GlcNAc) as substrates. The production of HA is mainly regulated by hyaluronan synthase 2 (HAS2), that can be controlled at different levels, from epigenetics to transcriptional and post-translational modifications. HA biosynthesis is an energy-consuming process and, along with HA catabolism, is strongly connected to the maintenance of metabolic homeostasis. The cytoplasmic pool of UDP-sugars is critical for HA synthesis. UDP-GlcNAc is an important nutrient sensor and serves as donor substrate for the O-GlcNAcylation of many cytosolic proteins, including HAS2. This post-translational modification stabilizes HAS2 in the membrane and increases HA production. Conversely, HAS2 can be phosphorylated by AMP activated protein kinase (AMPK), a master metabolic regulator activated by low ATP/AMP ratios, which inhibits HA secretion. Similarly, HAS2 expression and the deposition of HA within the pericellular coat are inhibited by sirtuin 1 (SIRT1), another important energetic sensor, confirming the tight connection between nutrients availability and HA metabolism.

The relationship between coronary artery disease and SIRT1 protein

Endothelial cell dysfunction proceeding with increased inflammation and monocyte increase is one of the main causes of vessel injury in CAD. SIRT1 (Sirtuin 1) protein plays an important role in the regulation of cellular physiological mechanisms. SIRT1 has roles in regulating angiogenesis and preventing endothelial dysfunction and reperfusion injury due to ischemia. Suppression of SIRT1 causes monocyte affinity due to endothelial dysfunction. Sirtuins activators are involved in pathologies of many diseases with promising treatments. The objective of this review is to summarize the current progress and future directions of sirtuin protein in the field of CAD.

AMPK‑SIRT1 pathway dysfunction contributes to neuron apoptosis and cognitive impairment induced by sevoflurane

The anesthetic sevoflurane (Sev) is widely used because of its low blood-gas partition coefficient and lack of pungency. However, the application of Sevmay lead to cognitive impairment later in life. Previous results have indicated that exposure to Sev-induced neuronal apoptosis and cognitive dysfunction in a rat model, but much work remains to elucidate the mechanism. In the present study, inhibition in the AMP-activated protein kinase/Sirtuin 1 (AMPK/SIRT1) signaling pathway and a decrease in AMPK/SIRT1 activity was found to occur concomitantly in neuronal apoptosis induced by Sev. AICAR, an activator of AMPK, was able to suppress Sev-induced neuronal apoptosis and SIRT1 activity reduction in vitro. Further animal studies also showed that AICAR treatment blocked the deleterious cognition and AMPK/SIRT1 activity reduction in the cognition impairment rats induced by Sev. Taken together, it was concluded that the AMPK/SIRT1 signaling pathway mediates neuronal apoptosis and cognition impairment induced by Sev. The study provides evidence that AMPK activation ameliorates Sev-induced cognitive deficits.

Effect of Selenium Supplementation on Expression of SIRT1 and PGC-1α Genes in Ulcerative Colitis Patients: a Double Blind Randomized Clinical Trial

Selenium (Se) supplementation may decrease the severity of ulcerative colitis (UC) through the activation of genes responsible for immune modulation. The present research was aimed to assess the effect of Se supplementation on the expression of silent information regulator 1 (SIRT1) and peroxisome proliferator-activated receptor γ coactivator-1α (PGC-1α) in UC patients. In a double-blind randomized parallel clinical trial, 100 patients with mild-to-moderate active UC met inclusion criteria and divided into 2 groups of treatment (50 patients received selenomethionine [200 µg daily]) and placebo (50 patients received placebo [1 capsule daily]) for 10 weeks. The expression rates of SIRT1 and PGC-1α were examined in the peripheral blood mononuclear cell (PBMC) using the real-time polymerase chain reaction. There was no considerable difference in the mean of baseline demographic and clinical characteristics between groups. Also, there were no significant differences in total energy intake, macronutrients, and micronutrients between groups. The SIRT1 gene expression in the Se group was significantly increased compared to the placebo (p < 0.001). An increase in the expression of the PGC-1α gene in the Se group was not statistically significant. It seems that Se supplementation caused a significant decrease in the inflammatory response of the colon by a significant increase in the expression of the SIRT1 gene.

Role of hydrogen sulfide in cardiovascular ageing

Cardiovascular diseases are the main cause of morbidity and mortality in the Western society and ageing is a relevant non-modifiable risk factor. Morphological and functional alterations at endothelial level represent first events of ageing, inevitably followed by vascular dysfunction and consequent atherosclerosis that deeply influences cardiovascular health. Indeed, myocardial hypertrophy and fibrosis typically occur and contribute to compromise overall cardiac output. As regards the intracellular molecular mechanisms involved in the cardiovascular ageing, an intricate network is emerging, revealing a role for many mediators, including SIRT1/AMPK/PCG1α pathway, anti-oxidants factors (i.e. Nrf-2 and FOXOs) and pro-inflammatory cytokines. Thus, the search for pharmacological and non-pharmacological strategies that can promote a "healthy ageing", in order to slow down age-related machinery, are currently an exciting challenge for the biomedical research. Interestingly, hydrogen sulfide (H₂S) has been recently recognized as a new player capable to influence intracellular machinery involved in ageing and then it is view as a potential target for preventing cardiovascular diseases. Therefore, this review is focused on the role of H₂S in cardiovascular ageing, and on the evidence of the relationship between progressive decline in endogenous H₂S levels and the onset of various cardiovascular age-related diseases.

Pum2 mediates Sirt1 mRNA decay and exacerbates hypoxia/reoxygenation-induced cardiomyocyte apoptosis

Pum2 is a ribonucleic acid binding protein that controls target mRNA turnover. It has been reported to be potentially associated with cardiac fibrosis. However, little is known about the role of Pum2 in cardiac disease. In this study, we found that Pum2 was upregulated in the rat heart tissue subjected to ischemia/reperfusion procedure and cultured neonatal rat ventricular cardiomyocytes (NRVMs) with hypoxia/reoxygenation (H/R) treatment. Further, knockdown of Pum2 showed a beneficial effect on H/R treated NRVMs through decreasing caspase 3-associated apoptosis, whereas overexpression of Pum2 increased H/R-induced NRVMs apoptosis. Moreover, our results demonstrated that Sirt1 was identified as the target of Pum2-mediated mRNA decay in cardiomyocytes, and two Pum2 binding elements were found in the 3'-untranslated region of Sirt1 mRNA. Additionally, overexpression of Pum2 prompted the acetylation of LKB1 by decreasing Sirt1's mRNA level, which in turn repressed the activity of AMPK pathway in both normoxic and H/R-treated NRVMs. Finally, our data indicated that the pro-apoptotic effect of Pum2 was dependent on Sirt1 and AMPK. Collectively, our results provide the evidence that Pum2-mediated Sirt1 mRNA decay plays a detrimental role in H/R-induced cardiomyocytes injury.

Study on the inhibitive effect of Catalpol on diabetic nephropathy

AIMS

Catalpol (Cat) can ameliorate oxide stress and inflammation caused by diabetic nephropathy (DN), but the molecular mechanisms are unclear. This study was designed to investigate the anti-diabetic effects of Cat and its potential mechanism.

MAIN METHODS

We constructed high-fat diet/streptozotocin (HFD/STZ)-induced DN mice and high glucose (HG)-induced podocyte model. The hypoglycemic effect of Cat was analyzed by general features of DN mice. Kidney function was detected via ELISA assay and Western blotting. Renal histopathology analysis was conducted via hematoxylin and eosin (H&E), Masson and periodic acid-silver metheramine (PASM) staining. Cellular viability was measured by TUNEL assay. In order to further study the potential mechanisms of Cat, various proteins in AMPK/SIRT1/NF-κB pathway were detected in DN mice and podocytes with siRNA-AMPK intervention using Western blotting, respectively.

KEY FINDINGS

We found hyperglycemia, renal structural and function abnormalities, and increased renal inflammation in DN mice. However, Cat effectively attenuated kidney damage caused by inflammation and increased AMPK, p-AMPK and SIRT1 levels. After AMPK-siRNA transfected into HG-induced podocyte model, AMPK, p-AMPK and SIRT1 levels were obviously decreased, while Cat reversed these chandes. The levels of p-NF-κB, ASC, Cleaved IL-1β, NLRP3, Cleaved caspase1 and GSDMD-N significantly decreased by Cat treatment both in DN mice and podocyte model, which indicated that Cat could activate AMPK/SIRT1/NF-κB pathway.

SIGNIFICANCE

Cat could effectively inhibit oxide stress and inflammation accompanied with pyroptosis and its mechanism might be related to AMPK/SIRT1/NF-κB pathway, indicating that Cat possessed potential value in the treatment of DN.

Polyphenols and obesity prevention: critical insights on molecular regulation, bioavailability and dose in preclinical and clinical settings

Obesity represents one of the most important public health challenges of the 21st century and is characterized by a multifactorial etiology in which environmental, behavioral, metabolic, and genetic factors work together. Despite the rapid increase in prevalence of obesity in the last decades, especially in children, it remains a preventable disease. To battle obesity a multisector approach promoting healthier lifestyle in terms of physical activity and nutrition is needed. Specifically, biologically active dietary compounds, as polyphenols, are able to modulate the expression of genes involved in the development and progression of obesity and its comorbidities as demonstrated by multiple studies using different obesity models. However, human studies focusing on the transcriptomic modulation by polyphenols in obese patients are still limited and do not often recapitulate the results obtained in preclinical setting likely due to the underestimation of some variables such as bioavailability, dose and form (native vs. metabolized) of polyphenols used. The aim of this review is to summarize the state-of-art of nutrigenomic in vitro, in vivo and ex vivo studies as well as clinical trials based on dietary polyphenols to fight obesity. We also critical discuss the variables to be considered to fill the gap between preclinical and clinical settings.

The Preventive Effects of Pterostilbene on the Exercise Intolerance and Circadian Misalignment of Mice Subjected to Sleep Restriction

SCOPE

The study investigates the effects of pterostilbene (PTE) on exercise endurance and circadian rhythm in sleep-restricted (SR) mice.

METHODS AND RESULTS

The SR model is established by keeping mice awake during the first 8 h of light period for 5 d and PTE (100 mg kg^-1 d^-1 ) is given once a day. PTE improves endurance in SR mice by significantly prolonging the exhaustive swimming time and ameliorating exercise fatigue biochemical parameters, including creatine kinase and lactate dehydrogenase. It is observed that PTE effectively regained mitochondrial function by improving mitochondrial swelling and maintaining oxidative phosphorylation system-related genes expression, and inhibited the decrease of mitochondrial biogenesis-related genes expression. Furthermore, PTE restores rhythms of AMP-activated protein kinase (AMPK) phosphorylation activity, silent information regulator 1 (SIRT1) deacetylation activity, and SIRT1-mediated peroxisome proliferator-activated receptor coactivator 1α (PGC-1α) deacetylation in SR mice. Finally, the results demonstrate that the AMPK/SIRT1/PGC-1α pathway may be correlated with the relationships between mitochondrial function and circadian rhythms, markedly regulating the expression of skeletal muscle clock genes, circadian locomotor output cycles kaput, and brain and muscle arnt-like 1.

CONCLUSIONS

PTE ameliorates SR-induced exercise intolerance associated with circadian misalignment and mitochondrial dysfunction through AMPK/SIRT1/PGC-1α pathway.

The Role of Reactive Oxygen Species in the Life Cycle of the Mitochondrion

Currently, it is known that, in living systems, free radicals and other reactive oxygen and nitrogen species play a double role, because they can cause oxidative damage and tissue dysfunction and serve as molecular signals activating stress responses that are beneficial to the organism. It is also known that mitochondria, because of their capacity to produce free radicals, play a major role in tissue oxidative damage and dysfunction and provide protection against excessive tissue dysfunction through several mechanisms, including the stimulation of permeability transition pore opening. This process leads to mitoptosis and mitophagy, two sequential processes that are a universal route of elimination of dysfunctional mitochondria and is essential to protect cells from the harm due to mitochondrial disordered metabolism. To date, there is significant evidence not only that the above processes are induced by enhanced reactive oxygen species (ROS) production, but also that such production is involved in the other phases of the mitochondrial life cycle. Accumulating evidence also suggests that these effects are mediated through the regulation of the expression and the activity of proteins that are engaged in processes such as genesis, fission, fusion, and removal of mitochondria. This review provides an account of the developments of the knowledge on the dynamics of the mitochondrial population, examining the mechanisms governing their genesis, life, and death, and elucidating the role played by free radicals in such processes.

Healthy Effects of Plant Polyphenols: Molecular Mechanisms

The increasing extension in life expectancy of human beings in developed countries is accompanied by a progressively greater rate of degenerative diseases associated with lifestyle and aging, most of which are still waiting for effective, not merely symptomatic, therapies. Accordingly, at present, the recommendations aimed at reducing the prevalence of these conditions in the population are limited to a safer lifestyle including physical/mental exercise, a reduced caloric intake, and a proper diet in a convivial environment. The claimed health benefits of the Mediterranean and Asian diets have been confirmed in many clinical trials and epidemiological surveys. These diets are characterized by several features, including low meat consumption, the intake of oils instead of fats as lipid sources, moderate amounts of red wine, and significant amounts of fresh fruit and vegetables. In particular, the latter have attracted popular and scientific attention for their content, though in reduced amounts, of a number of molecules increasingly investigated for their healthy properties. Among the latter, plant polyphenols have raised remarkable interest in the scientific community; in fact, several clinical trials have confirmed that many health benefits of the Mediterranean/Asian diets can be traced back to the presence of significant amounts of these molecules, even though, in some cases, contradictory results have been reported, which highlights the need for further investigation. In light of the results of these trials, recent research has sought to provide information on the biochemical, molecular, epigenetic, and cell biology modifications by plant polyphenols in cell, organismal, animal, and human models of cancer, metabolic, and neurodegenerative pathologies, notably Alzheimer's and Parkinson disease. The findings reported in the last decade are starting to help to decipher the complex relations between plant polyphenols and cell homeostatic systems including metabolic and redox equilibrium, proteostasis, and the inflammatory response, establishing an increasingly solid molecular basis for the healthy effects of these molecules. Taken together, the data currently available, though still incomplete, are providing a rationale for the possible use of natural polyphenols, or their molecular scaffolds, as nutraceuticals to contrast aging and to combat many associated pathologies.

Long-term caloric restriction activates the myocardial SIRT1/AMPK/PGC-1α pathway in C57BL/6J male mice

Background

Caloric restriction (CR) can help in improving heart function. There is as yet no consensus on the mechanism of the effect of CR. Silent mating-type information regulation 1 (SIRT1), adenosine monophosphate-activated protein kinase (AMPK), and mTOR are key players in metabolic stress management. We aimed to explore the effect of CR on the myocardial SIRT1/AMPK/mTOR pathway in mice.

Methods

Thirty-six 6-week-old male C57BL/6J mice were randomly divided into three groups: normal control group (NC group, n = 12), high-energy group (HE group, n = 12) and CR group (n = 12) according to different diets. After 11 months, western blot was used to examine proteins such as p-AMPK, peroxisome proliferator-activated receptor gamma coactivator 1-alpha (PGC-1α), SIRT1, and p-mTOR, whereas real-time PCR was used to examine the expression of AMPK, PGC-1α, and SIRT1 transcripts.

Results

Compared to the HE group, the CR group displayed increased expression of myocardial p-AMPK protein, SIRT1 protein and mRNA, and PGC-1a mRNA. However, no difference was observed in the expression of p-mTOR protein and mTOR mRNA in the myocardium among the three groups.

Conclusions

CR improves the SIRT1/AMPK/PGC-1α pathway in mice myocardium with no effect on the mTOR pathway.

Methylglyoxal-Dependent Glycative Stress and Deregulation of SIRT1 Functional Network in the Ovary of PCOS Mice

Advanced glycation end-products (AGEs) are involved in the pathogenesis and consequences of polycystic ovary syndrome (PCOS), a complex metabolic disorder associated with female infertility. The most powerful AGE precursor is methylglyoxal (MG), a byproduct of glycolysis, that is detoxified by the glyoxalase system. By using a PCOS mouse model induced by administration of dehydroepiandrosterone (DHEA), we investigated whether MG-dependent glycative stress contributes to ovarian PCOS phenotype and explored changes in the Sirtuin 1 (SIRT1) functional network regulating mitochondrial functions and cell survival. In addition to anovulation and reduced oocyte quality, DHEA ovaries revealed altered collagen deposition, increased vascularization, lipid droplets accumulation and altered steroidogenesis. Here we observed increased intraovarian MG-AGE levels in association with enhanced expression of receptor for AGEs (RAGEs) and deregulation of the glyoxalase system, hallmarks of glycative stress. Moreover, DHEA mice exhibited enhanced ovarian expression of SIRT1 along with increased protein levels of SIRT3 and superoxide dismutase 2 (SOD2), and decreased peroxisome proliferator-activated receptor gamma co-activator 1 alpha (PGC1α), mitochondrial transcriptional factor A (mtTFA) and translocase of outer mitochondrial membrane 20 (TOMM20). Finally, the presence of autophagy protein markers and increased AMP-activated protein kinase (AMPK) suggested the involvement of SIRT1/AMPK axis in autophagy activation. Overall, present findings demonstrate that MG-dependent glycative stress is involved in ovarian dysfunctions associated to PCOS and support the hypothesis of a SIRT1-dependent adaptive response.

A systematic review on the mechanisms of vitamin K effects on the complications of diabetes and pre-diabetes

Diabetes mellitus and pre-diabetes are prevalent endocrine disorders associated with substantial morbidity and premature mortality. Vitamin K is known to have several beneficial effects on complications of diabetes and pre-diabetes. However, systematic consolidation of evidence is required to quantify these effects in order to inform clinical practice and research. A systematic search in PubMed, Scopus, Embase, ProQuest, and Google Scholar databases was undertaken from database inception up to October 2018 to evaluate functional roles of different forms of vitamin K on diabetes and pre-diabetes. From 3,734 identified records, nine articles met the inclusion criteria and were evaluated. Vitamin K supplementation was found to be associated with significant reductions in blood glucose (six studies), increased fasting serum insulin (four studies), reduced hemoglobin A1c (three studies), reduced homeostatic model assessment-insulin resistance index (HOMA-IR) (two studies), and increased ß-cell function (two studies) in diabetic animal studies. Following 2-hour oral glucose tolerance test, vitamin K supplementation was observed to be effective in reducing blood glucose and insulin levels in the pre-diabetic population. However, no evidence of effect was observed for fasting blood sugar, insulin, HOMA-IR, and homeostatic model assessment-β-cell function index (two studies). A statistically significant effect was also noted with vitamin K in improving dyslipidemia (three studies) as well as oxidative stress and inflammatory markers (five studies) in diabetic animals. In conclusion, clinical trials and animal studies confirm that vitamin K supplementation may improve both clinical features and complications of diabetes and pre-diabetes. However, quantification of clinical efficacy in the pre-diabetic population and among individuals with comorbidities requires further investigation.

The relevance of AMP-activated protein kinase in insulin-secreting β cells: a potential target for improving β cell function?

AMP-activated protein kinase (AMPK) is present in different kinds of metabolically active cells. AMPK is an important intracellular energy sensor and plays a relevant role in whole-body energy homeostasis. AMPK is activated, among others, in response to glucose deprivation, caloric restriction and increased physical activity. Upon activation, AMPK affects metabolic pathways leading to increased formation of ATP and simultaneously reducing ATP-consuming processes. AMPK is also expressed in pancreatic β cells and is largely regulated by glucose, which is the main physiological stimulator of insulin secretion. Results of in vitro studies clearly show that glucose-induced insulin release is associated with a concomitant inhibition of AMPK in β cells. However, pharmacological activation of AMPK significantly potentiates the insulin-secretory response of β cells to glucose and to some other stimuli. This effect is primarily due to increased intracellular calcium concentrations. AMPK is also involved in the regulation of gene expression and may protect β cells against glucolipotoxic conditions. It was shown that in pancreatic islets of humans with type 2 diabetes, AMPK is downregulated. Moreover, studies with animal models demonstrated impaired link between glucose and AMPK activity in pancreatic islet cells. These data suggest that AMPK may be a target for compounds improving the functionality of β cells. However, more studies are required to better elucidate the relevance of AMPK in the (patho)physiology of the insulin-secreting cells.

Design and in silico modeling of Indoloquinoxaline incorporated keratin nanoparticles for modulation of glucose metabolism in 3T3-L1 adipocytes

The following study was done to assess the glucose utilizing efficiency of Indoloquinoxaline derivative incorporated keratin nanoparticles (NPs) in 3T3-L1 adipocytes. Indoloquinoxaline derivative had wide range of biological activities including antidiabetic activity. In this view, Indoloquinoxaline moiety containing N, N-dimethyl (3-fluoro-6H-indolo [3,2-b] quinoxalin-6-yl) methanamine compound was designed and synthesized, and further it is incorporated into keratin nanoparticles. The formulated NPs, drug entrapment efficiency, releasing capacity, stability, and physicochemical properties were characterized by various spectral analyzer and obtained results of characterizations were confirmed the properties of NPs. The analysis of mechanism underlying the glucose utilization of NPs was examined through molecular docking with identified target, and observed in silico study reports shown strong interaction of NPs in the binding pockets of AMPK and PTP1B. Based on the in silico screening, the formulated NPs was performed for in vitro cellular viability and glucose uptake studies on 3T3-L1 adipocytes. Interestingly, 40 μg of NPs displayed 78.2 ± 2.76% cellular viability, and no cell death was observed at lower concentrations. Further, the concentration dependent glucose utilization was observed at different concentrations of NPs in 3T3-L1 adipocytes. The results of NPs (40 μg) on glucose utilization have revealed eminent result 58.56 ± 4.54% compared to that of Metformin (10 μM) and Insulin (10 μM). The identified results clearly indicated that Indoloquinoxaline derivative incorporated keratin NPs significantly increased glucose utilization efficiency and protect the cells against the insulin resistance.

Metabolic reprogramming in memory CD4 T cell responses of old adults

To determine whether aging affects the ability of T cells to undergo metabolic reprogramming upon activation, we compared CD4 T cell responses after polyclonal in vitro stimulation. Compared to younger adults, CD4 memory T cells from healthy older individuals exhibited a higher upregulation of oxidative phosphorylation with increased production of reactive oxygen species and intracellular and secreted ATP. Increased ATP secretion led to increased purinergic signaling and P2X7-dependent increases in cytoplasmic calcium. The increased mitochondrial activity was not due to a difference in activation-induced mitochondrial biogenesis. Expression of carnitine palmitoyl transferase 1 was higher, conversely that of fatty acid synthase was reduced in older T cells, resulting in increased fatty acid oxidation, while depleting intracellular lipid stores. The aged CD4 memory T cells therefore maintain a more catabolic state in lipid metabolism, while their ability to upregulate glycolysis upon activation is preserved.