Calorie restriction: is AMPK a key sensor and effector?

Nutrition in Cancer Therapy in the Elderly-An Epigenetic Connection?

The continuous increase in life expectancy results in a steady increase of cancer risk, which consequently increases the population of older adults with cancer. Older adults have their age-related nutritional needs and often suffer from comorbidities that may affect cancer therapy. They frequently are malnourished and present advanced-stage cancer. Therefore, this group of patients requires a special multidisciplinary approach to optimize their therapy and increase quality of life impaired by aging, cancer, and the side effects of therapy. Evaluation strategies, taking advantage of comprehensive geriatric assessment tools, including the comprehensive geriatric assessment (CGA), can help individualize treatment. As epigenetics, an emerging element of the regulation of gene expression, is involved in both aging and cancer and the epigenetic profile can be modulated by the diet, it seems to be a candidate to assist with planning a nutritional intervention in elderly populations with cancer. In this review, we present problems associated with the diet and nutrition in the elderly undergoing active cancer therapy and provide some information on epigenetic aspects of aging and cancer transformation. Nutritional interventions modulating the epigenetic profile, including caloric restriction and basal diet with modifications (elimination diet, supplementary diet) are discussed as the ways to improve the efficacy of cancer therapy and maintain the quality of life of older adults with cancer.

Interaction of Adipocyte Metabolic and Immune Functions Through TBK1

Adipocytes and adipose tissue play critical roles in the regulation of metabolic homeostasis. In obesity and obesity-associated metabolic diseases, immune cells infiltrate into adipose tissues. Interaction between adipocytes and immune cells re-shapes both metabolic and immune properties of adipose tissue and dramatically changes metabolic set points. Both the expression and activity of the non-canonical IKK family member TBK1 are induced in adipose tissues during diet-induced obesity. TBK1 plays important roles in the regulation of both metabolism and inflammation in adipose tissue and thus affects glucose and energy metabolism. Here we review the regulation and functions of TBK1 and the molecular mechanisms by which TBK1 regulates both metabolism and inflammation in adipose tissue. Finally, we discuss the potential of a TBK1/IKKε inhibitor as a new therapy for metabolic diseases.

Transcriptional Control of Circadian Rhythms and Metabolism: A Matter of Time and Space

All biological processes, living organisms, and ecosystems have evolved with the Sun that confers a 24-hour periodicity to life on Earth. Circadian rhythms arose from evolutionary needs to maximize daily organismal fitness by enabling organisms to mount anticipatory and adaptive responses to recurrent light-dark cycles and associated environmental changes. The clock is a conserved feature in nearly all forms of life, ranging from prokaryotes to virtually every cell of multicellular eukaryotes. The mammalian clock comprises transcription factors interlocked in negative feedback loops, which generate circadian expression of genes that coordinate rhythmic physiology. In this review, we highlight previous and recent studies that have advanced our understanding of the transcriptional architecture of the mammalian clock, with a specific focus on epigenetic mechanisms, transcriptomics, and 3-dimensional chromatin architecture. In addition, we discuss reciprocal ways in which the clock and metabolism regulate each other to generate metabolic rhythms. We also highlight implications of circadian biology in human health, ranging from genetic and environment disruptions of the clock to novel therapeutic opportunities for circadian medicine. Finally, we explore remaining fundamental questions and future challenges to advancing the field forward.

How Does Our Brain Process Sugars and Non-Nutritive Sweeteners Differently: A Systematic Review on Functional Magnetic Resonance Imaging Studies

This systematic review aimed to reveal the differential brain processing of sugars and sweeteners in humans. Functional magnetic resonance imaging studies published up to 2019 were retrieved from two databases and were included into the review if they evaluated the effects of both sugars and sweeteners on the subjects’ brain responses, during tasting and right after ingestion. Twenty studies fulfilled the inclusion criteria. The number of participants per study ranged from 5 to 42, with a total number of study participants at 396. Seven studies recruited both males and females, 7 were all-female and 6 were all-male. There was no consistent pattern showing that sugar or sweeteners elicited larger brain responses. Commonly involved brain regions were insula/operculum, cingulate and striatum, brainstem, hypothalamus and the ventral tegmental area. Future studies, therefore, should recruit a larger sample size, adopt a standardized fasting duration (preferably 12 h overnight, which is the most common practice and brain responses are larger in the state of hunger), and reported results with familywise-error rate (FWE)-corrected statistics. Every study should report the differential brain activation between sugar and non-nutritive sweetener conditions regardless of the complexity of their experiment design. These measures would enable a meta-analysis, pooling data across studies in a meaningful manner.

Metabolomics of human fasting: new insights about old questions

Since ancient days, human fasting has been performed for religious or political reasons. More recently, fasting has been employed as an effective therapy for weight reduction by obese people, and numerous studies have investigated the physiology of fasting by obese subjects. Well-established fasting markers (butyrates, BCAAs and carnitines) were considered essential energy substitutes after glycogen storage depletion. However, a recently developed metabolomic approach has unravelled previously unappreciated aspects of fasting. Surprisingly, one-third (44) of 120 metabolites investigated increase during 58 h of fasting, including antioxidative metabolites (carnosine, ophthalmic acid, ergothioneine and urates) and metabolites of entire pathways, such as the pentose phosphate pathway. Signalling metabolites (3-hydroxybutyrate and 2-oxoglutarate) and purines/pyrimidines may also serve as transcriptional modulators. Thus, prolonged fasting activates both global catabolism and anabolism, reprogramming metabolic homeostasis.

Metabolic Communication and Healthy Aging: Where Should We Focus Our Energy?

Aging is associated with a loss of metabolic homeostasis and plasticity, which is causally linked to multiple age-onset pathologies. The majority of the interventions-genetic, dietary, and pharmacological-that have been found to slow aging and protect against age-related disease in various organisms do so by targeting central metabolic pathways. However, targeting metabolic pathways chronically and ubiquitously makes it difficult to define the downstream effects responsible for lifespan extension and often results in negative effects on growth and health, limiting therapeutic potential. Insight into how metabolic signals are relayed between tissues, cells, and organelles opens up new avenues to target metabolic regulators locally rather than globally for healthy aging. In this review, we discuss the pro-longevity effects of targeting metabolic pathways in specific tissues and how these interventions communicate with distal cells to modulate aging. These studies may be crucial in designing interventions that promote longevity without negative health consequences.

Testosterone suppression does not exacerbate disuse atrophy and impairs muscle recovery that is not rescued by high protein

Androgen deprivation therapy (ADT) decreases muscle mass, force, and physical activity levels, but it is unclear whether disuse atrophy and testosterone suppression are additive. Additionally, conflicting reports exist on load-mediated hypertrophy during ADT and if protein supplementation offsets these deficits. This study sought to determine the role of testosterone suppression and a high-protein diet on 1) immobilization-induced atrophy and 2) muscle regrowth during reloading. Eight-week-old male Fischer 344 rats underwent sham surgery (Sham), castration surgery (ORX), or ORX and a high-casein diet supplemented with branched-chain amino acids (BCAA) (ORX+CAS/AA) followed by 10 days of unilateral immobilization (IMM) and 0, 6, or 14 days of reloading. With IMM, body mass gains were ~8% greater than ORX and ORX+CAS/AA that increased to 15% during reloading (both P < 0.01). IMM reduced muscle mass by 11-34% (all P < 0.01) and extensor digitorum longus and soleus (SOL) force by 21% and 49% (both P < 0.01), respectively, with no group differences. During reloading, castration reduced gastrocnemius mass (~12%) at 6 days and SOL mass (~20%) and SOL force recovery (~46%) at 14 days relative to Sham (all P < 0.05). Specific force reduced castration deficits, indicating that muscle atrophy was a key contributor. IMM decreased SOL cross-sectional area by 30.3% (P < 0.001), with a trend for reduced regrowth in ORX and ORX+CAS/AA following reloading (P = 0.083). Castration did not exacerbate disuse atrophy but may impair recovery of muscle function, with no benefit from a CAS/AA diet during reloading. Examining functional outcomes in addition to muscle mass during dietary interventions provides novel insights into muscle regrowth during ADT.NEW & NOTEWORTHY Low testosterone levels during skeletal muscle disuse did not worsen declines in muscle mass and function, although hypogonadism may attenuate recovery during subsequent reloading. Diets high in casein did not improve outcomes during immobilization or reloading. Practical strategies are needed that do not compromise caloric intake yet provide effective protein doses to augment these adverse effects.

The Role of AMPK Activation for Cardioprotection in Doxorubicin-Induced Cardiotoxicity

Doxorubicin is a commonly used chemotherapeutic agent for the treatment of a range of cancers, but despite its success in improving cancer survival rates, doxorubicin is cardiotoxic and can lead to congestive heart failure. Therapeutic options for this patient group are limited to standard heart failure medications with the only drug specific for doxorubicin cardiotoxicity to reach FDA approval being dexrazoxane, an iron-chelating agent targeting oxidative stress. However, dexrazoxane has failed to live up to its expectations from preclinical studies while also bringing up concerns about its safety. Despite decades of research, the molecular mechanisms of doxorubicin cardiotoxicity are still poorly understood and oxidative stress is no longer considered to be the sole evil. Mitochondrial impairment, increased apoptosis, dysregulated autophagy and increased fibrosis have also been shown to be crucial players in doxorubicin cardiotoxicity. These cellular processes are all linked by one highly conserved intracellular kinase: adenosine monophosphate-activated protein kinase (AMPK). AMPK regulates mitochondrial biogenesis via PGC1α signalling, increases oxidative mitochondrial metabolism, decreases apoptosis through inhibition of mTOR signalling, increases autophagy through ULK1 and decreases fibrosis through inhibition of TGFβ signalling. AMPK therefore sits at the control point of many mechanisms shown to be involved in doxorubicin cardiotoxicity and cardiac AMPK signalling itself has been shown to be impaired by doxorubicin. In this review, we introduce different agents known to activate AMPK (metformin, statins, resveratrol, thiazolidinediones, AICAR, specific AMPK activators) as well as exercise and dietary restriction, and we discuss the existing evidence for their potential role in cardioprotection from doxorubicin cardiotoxicity.

Effects of a ketogenic diet in overweight women with polycystic ovary syndrome

Background

Polycystic ovary syndrome (PCOS) is the most common endocrine disorder in women during reproductive age. It is characterised clinically by oligo-ovulation or anovulation, hyper-androgenism, and the presence of polycystic ovaries. It is associated with an increased prevalence of metabolic syndrome, cardiovascular disease and type 2 diabetes. The onset of PCOS has been associated to several hereditary and environmental factors, but insulin resistance plays a key pathogenetic role. We sought to investigate the effects of a ketogenic diet (KD) on women of childbearing age with a diagnosis of PCOS.

Methods

Fourteen overweight women with diagnosis of PCOS underwent to a ketogenic Mediterranean diet with phyoextracts (KEMEPHY) for 12 week. Changes in body weight, body mass index (BMI), fat body mass (FBM), lean body mass (LBM), visceral adipose tissue (VAT), insulin, glucose, HOMA-IR, total cholesterol, low density lipoprotein (LDL), high density lipoprotein (HDL), triglycerides (TGs), total and free testosterone, luteinizing hormone (LH), follicle stimulating hormone (FSH); dehydroepiandrosterone sulfate (DHEAs), estradiol, progesterone, sex hormone binding globulin (SHBG) and Ferriman Gallwey score were evaluated.

Results

After 12 weeks, anthropometric and body composition measurements revealed a significant reduction of body weight (− 9.43 kg), BMI (− 3.35), FBM (8.29 kg) and VAT. There was a significant, slightly decrease of LBM. A significant decrease in glucose and insulin blood levels were observed, together with a significant improvement of HOMA-IR. A significant decrease of triglycerides, total cholesterol and LDL were observed along with a rise in HDL levels. The LH/FSH ratio, LH total and free testosterone, and DHEAS blood levels were also significantly reduced. Estradiol, progesterone and SHBG increased. The Ferriman Gallwey Score was slightly, although not significantly, reduced.

Conclusions

Our results suggest that a KD may be considered as a valuable non pharmacological treatment for PCOS. Longer treatment periods should be tested to verify the effect of a KD on the dermatological aspects of PCOS.

Trial registration Clinicaltrial.gov, NCT04163120, registrered 10 November 2019, retrospectively registered, https://clinicaltrials.gov.

Redox-mediated regulation of aging and healthspan by an evolutionarily conserved transcription factor HLH-2/Tcf3/E2A

Physiological aging is a complex process, influenced by a plethora of genetic and environmental factors. While being far from fully understood, a number of common aging hallmarks have been elucidated in recent years. Among these, transcriptomic alterations are hypothesized to represent a crucial early manifestation of aging. Accordingly, several transcription factors (TFs) have previously been identified as important modulators of lifespan in evolutionarily distant model organisms. Based on a set of TFs conserved between nematodes, zebrafish, mice, and humans, we here perform a RNA interference (RNAi) screen in C. elegans to discover evolutionarily conserved TFs impacting aging. We identify a basic helix-loop-helix TF, named HLH-2 in nematodes (Tcf3/E2A in mammals), to exert a pronounced lifespan-extending effect in C. elegans upon impairment. We further show that its impairment impacts cellular energy metabolism, increases parameters of healthy aging, and extends nematodal lifespan in a ROS-dependent manner. We then identify arginine kinases, orthologues of mammalian creatine kinases, as a target of HLH-2 transcriptional regulation, serving to mediate the healthspan-promoting effects observed upon impairment of hlh-2 expression. Consistently, HLH-2 is shown to epistatically interact with core components of known lifespan-regulating pathways, i.e. AAK-2/AMPK and LET-363/mTOR, as well as the aging-related TFs SKN-1/Nrf2 and HSF-1. Lastly, single-nucelotide polymorphisms (SNPs) in Tcf3/E2A are associated with exceptional longevity in humans. Together, these findings demonstrate that HLH-2 regulates energy metabolism via arginine kinases and thereby affects the aging phenotype dependent on ROS-signaling and established canonical effectors.

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A C. elegans RNAi screen identifies conserved aging-related transcription factors.

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Impairment of transcription factor hlh-2 has the most pronounced effect on lifespan.

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C. elegans HLH-2 affects cellular energy homeostasis and redox signaling.

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HLH-2 modulates arginine kinase to interact with downstream longevity pathways.

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Polymorphisms (SNPs) in the hlh-2 orthologue Tcf3/E2A are linked to human longevity.

Food with calorie restriction reduces the development of atherosclerosis in apoE-deficient mice

Calorie restriction (CR) ameliorates various diseases including cardiovascular disease. However, its protection and underlying mechanisms against atherosclerosis remain un-fully elucidated. In this study, we fed apoE deficient (apoE^-/-) mice in Control group a high-fat diet (HFD, 21% fat plus 0.5% cholesterol) or in CR group a CR diet (CRD, 2% fat plus 0.5% cholesterol, ∼40% calorie restriction and same levels of cholesterol, vitamins, minerals and amino acids as in HFD). After 16 weeks feeding, compared with HFD, CRD substantially reduced atherosclerosis in mice. CRD increased SMC and collagen content but reduced macrophage content, necrotic core and vascular calcification in lesion areas. Mechanistically, CRD attenuated bodyweight gain, improved lipid profiles but had little effect on macrophage lipid metabolism. CRD also inhibited expression of inflammatory molecules in lesions. Taken together, our study demonstrates CRD effectively reduces atherosclerosis in apoE^-/- mice, suggesting it as a potent and reproducible therapy for atherosclerosis management.

Five months of voluntary wheel running downregulates skeletal muscle LINE-1 gene expression in rats

Transposable elements (TEs) are mobile DNA and constitute approximately half of the human genome. LINE-1 (L1) is the only active autonomous TE in the mammalian genome and has been implicated in a number of diseases as well as aging. We have previously reported that skeletal muscle L1 expression is lower following acute and chronic exercise training in humans. Herein, we used a rodent model of voluntary wheel running to determine whether long-term exercise training affects markers of skeletal muscle L1 regulation. Selectively bred high-running female Wistar rats (n = 11 per group) were either given access to a running wheel (EX) or not (SED) at 5 wk of age, and these conditions were maintained until 27 wk of age. Thereafter, mixed gastrocnemius tissue was harvested and analyzed for L1 mRNA expression and DNA content along with other L1 regulation markers. We observed significantly (P < 0.05) lower L1 mRNA expression, higher L1 DNA methylation, and less L1 DNA in accessible chromatin regions in EX versus SED rats. We followed these experiments with 3-h in vitro drug treatments in L6 myotubes to mimic transient exercise-specific signaling events. The AMP-activated protein kinase (AMPK) agonist 5-aminoimidazole-4-carboxamide ribonucleotide (AICAR; 4 mM) significantly decreased L1 mRNA expression in L6 myotubes. However, this effect was not facilitated through increased L1 DNA methylation. Collectively, these data suggest that long-term voluntary wheel running downregulates skeletal muscle L1 mRNA, and this may occur through chromatin modifications. Enhanced AMPK signaling with repetitive exercise bouts may also decrease L1 mRNA expression, although the mechanism of action remains unknown.

Recent Advances in Anti-Aging Medicine

A rapidly aging population in Korea has led to increased attention in the field of anti-aging medicine. The purpose of anti-aging medicine is to slow, stop, or reverse the aging process and its associated effects, such as disability and frailty. Anti-aging medicine is emerging as a growing industry, but many supplements or protocols are available that do not have scientific evidence to support their claims. In this review, the mechanisms of action and the clinical implications of anti-aging interventions were examined and explained. Calorie restriction mimetics define compounds that imitate the outcome of calorie restriction, including an activator of AMP protein kinase (metformin), inhibitor of growth hormone/insulin-like growth factor-1 axis (pegvisomant), inhibitor of mammalian target of rapamycin (rapamycin), and activator of the sirtuin pathway (resveratrol). Hormonal replacement has also been widely used in the elderly population to improve their quality of life. Manipulating healthy gut microbiota through prebiotic/probiotics or fecal microbiota transplantation has significant potential in anti-aging medicine. Vitamin D is expected to be a primary anti-aging medicine in the near future due to its numerous positive effects in the elderly population.

Cell organelles and yeast longevity: an intertwined regulation

Organelles are dynamic structures of a eukaryotic cell that compartmentalize various essential functions and regulate optimum functioning. On the other hand, ageing is an inevitable phenomenon that leads to irreversible cellular damage and affects optimum functioning of cells. Recent research shows compelling evidence that connects organelle dysfunction to ageing-related diseases/disorders. Studies in several model systems including yeast have led to seminal contributions to the field of ageing in uncovering novel pathways, proteins and their functions, identification of pro- and anti-ageing factors and so on. In this review, we present a comprehensive overview of findings that highlight the role of organelles in ageing and ageing-associated functions/pathways in yeast.

Peroxisomes in Immune Response and Inflammation

The immune response is essential to protect organisms from infection and an altered self. An organism’s overall metabolic status is now recognized as an important and long-overlooked mediator of immunity and has spurred new explorations of immune-related metabolic abnormalities. Peroxisomes are essential metabolic organelles with a central role in the synthesis and turnover of complex lipids and reactive species. Peroxisomes have recently been identified as pivotal regulators of immune functions and inflammation in the development and during infection, defining a new branch of immunometabolism. This review summarizes the current evidence that has helped to identify peroxisomes as central regulators of immunity and highlights the peroxisomal proteins and metabolites that have acquired relevance in human pathologies for their link to the development of inflammation, neuropathies, aging and cancer. This review then describes how peroxisomes govern immune signaling strategies such as phagocytosis and cytokine production and their relevance in fighting bacterial and viral infections. The mechanisms by which peroxisomes either control the activation of the immune response or trigger cellular metabolic changes that activate and resolve immune responses are also described.

Resveratrol cytotoxicity is energy-dependent

Resveratrol is a phytochemical that may promote health. However, it has also been reported to be a toxic compound. The molecular mechanism by which resveratrol acts remains unclear. The inhibition of the oxidative phosphorylation (OXPHOS) pathway appears to be the molecular mechanism of resveratrol. Taking this into account, we propose that the cytotoxic properties of resveratrol depend on the energy (e.g., carbohydrates, lipids, and proteins) availability in the cells. In this regard, in a condition with low energy accessibility, resveratrol could enhance ATP starvation to lethal levels. In contrast, when cells are supplemented with high quantities of energy and resveratrol, the inhibition of OXPHOS might produce a low-energy environment, mimicking the beneficial effects of caloric restriction. This review suggests that investigating a possible complex relationship between caloric intake and the differential effects of resveratrol on OXPHOS may be justified. PRACTICAL APPLICATIONS: A low-calorie diet accompanied by significant levels of resveratrol might modify cellular bioenergetics, which could impact cellular viability and enhance the anti-cancer properties of resveratrol.

Skeletal muscle LINE-1 ORF1 mRNA is higher in older humans but decreases with endurance exercise and is negatively associated with higher physical activity

The long interspersed nuclear element-1 (L1) is a retrotransposon that constitutes 17% of the human genome and is associated with various diseases and aging. Estimates suggest that ~100 L1 copies are capable of copying and pasting into other regions of the genome. Herein, we examined if skeletal muscle L1 markers are affected by aging or an acute bout of cycling exercise in humans. Apparently healthy younger (23 ± 3 y, n = 15) and older participants (58 ± 8 y, n = 15) donated a vastus lateralis biopsy before 1 h of cycling exercise (PRE) at ~70% of heart rate reserve. Second (2 h) and third (8 h) postexercise muscle biopsies were also obtained. L1 DNA and mRNA expression were quantified using three primer sets [5' untranslated region (UTR), L1.3, and ORF1]. 5'UTR and L1.3 DNA methylation as well as ORF1 protein expression were also quantified. PRE 5'UTR, ORF1, or L1.3 DNA were not different between age groups (P > 0.05). ORF1 mRNA was greater in older versus younger participants (P = 0.014), and cycling lowered this marker at 2 h versus PRE (P = 0.027). 5'UTR and L1.3 DNA methylation were higher in younger versus older participants (P < 0.05). Accelerometry data collected during a 2-wk period before the exercise bout indicated higher moderate-to-vigorous physical activity (MVPA) levels per day was associated with lower PRE ORF1 mRNA in all participants (r = -0.398, P = 0.032). In summary, skeletal muscle ORF1 mRNA is higher in older apparently healthy humans, which may be related to lower DNA methylation patterns. ORF1 mRNA is also reduced with endurance exercise and is negatively associated with higher daily MVPA levels.NEW & NOTEWORTHY The long interspersed nuclear element-1 (L1) gene is highly abundant in the genome and encodes for an autonomous retrotransposon, which is capable of copying and pasting itself into other portions of the genome. This is the first study in humans to demonstrate that certain aspects of skeletal muscle L1 activity are altered with aging. Additionally, this is the first study in humans to demonstrate that L1 ORF1 mRNA levels decrease after a bout of endurance exercise, regardless of age.

AMPK activation inhibits the functions of myeloid-derived suppressor cells (MDSC): impact on cancer and aging

AMP-activated protein kinase (AMPK) has a crucial role not only in the regulation of tissue energy metabolism but it can also control immune responses through its cooperation with immune signaling pathways, thus affecting immunometabolism and the functions of immune cells. It is known that AMPK signaling inhibits the activity of the NF-κB system and thus suppresses pro-inflammatory responses. Interestingly, AMPK activation can inhibit several major immune signaling pathways, e.g., the JAK-STAT, NF-κB, C/EBPβ, CHOP, and HIF-1α pathways, which induce the expansion and activation of myeloid-derived suppressor cells (MDSC). MDSCs induce an immunosuppressive microenvironment in tumors and thus allow the escape of tumor cells from immune surveillance. Chronic inflammation has a key role in the expansion and activation of MDSCs in both tumors and inflammatory disorders. The numbers of MDSCs also significantly increase during the aging process concurrently with the immunosenescence associated with chronic low-grade inflammation. Increased fatty acid oxidation and lactate produced by aerobic glycolysis are important immunometabolic enhancers of MDSC functions. However, it seems that AMPK signaling regulates the functions of MDSCs in a context-dependent manner. Currently, the activators of AMPK signaling are promising drug candidates for cancer therapy and possibly for the extension of healthspan and lifespan. We will describe in detail the AMPK-mediated regulation of the signaling pathways controlling the expansion and activation of immunosuppressive MDSCs. We will propose that the beneficial effects mediated by AMPK activation, e.g., in cancers and the aging process, could be induced by the inhibition of MDSC functions.

Guarana supplementation attenuated obesity, insulin resistance, and adipokines dysregulation induced by a standardized human Western diet via brown adipose tissue activation

Obesity is a metabolic disorder associated with adverse health consequences that has increased worldwide at an epidemic rate. This has encouraged many people to utilize nonprescription herbal supplements for weight loss without knowledge of their safety or efficacy. However, mounting evidence has shown that some herbal supplements used for weight loss are associated with adverse effects. Guarana seed powder is a popular nonprescription dietary herb supplement marketed for weight loss, but no study has demonstrated its efficacy or safety when administered alone. Wistar rats were fed four different diets (low-fat diet and Western diet with or without guarana supplementation) for 18 weeks. Metabolic parameters, gut microbiota changes, and toxicity were then characterized. Guarana seed powder supplementation prevented weight gain, insulin resistance, and adipokine dysregulation induced by Western diet compared with the control diet. Guarana induced brown adipose tissue expansion, mitochondrial biogenesis, uncoupling protein-1 overexpression, AMPK activation, and minor changes in gut microbiota. Molecular docking suggested a direct activation of AMPK by four guarana compounds tested here. We propose that brown adipose tissue activation is one of the action mechanisms involved in guarana supplementation-induced weight loss and that direct AMPK activation may underlie this mechanism. In summary, guarana is an attractive potential therapeutic agent to treat obesity.

Cytoplasmic and Mitochondrial NADPH-Coupled Redox Systems in the Regulation of Aging

The reduced form of nicotinamide adenine dinucleotide phosphate (NADPH) protects against redox stress by providing reducing equivalents to antioxidants such as glutathione and thioredoxin. NADPH levels decline with aging in several tissues, but whether this is a major driving force for the aging process has not been well established. Global or neural overexpression of several cytoplasmic enzymes that synthesize NADPH have been shown to extend lifespan in model organisms such as Drosophila suggesting a positive relationship between cytoplasmic NADPH levels and longevity. Mitochondrial NADPH plays an important role in the protection against redox stress and cell death and mitochondrial NADPH-utilizing thioredoxin reductase 2 levels correlate with species longevity in cells from rodents and primates. Mitochondrial NADPH shuttles allow for some NADPH flux between the cytoplasm and mitochondria. Since a decline of nicotinamide adenine dinucleotide (NAD⁺) is linked with aging and because NADP⁺ is exclusively synthesized from NAD⁺ by cytoplasmic and mitochondrial NAD⁺ kinases, a decline in the cytoplasmic or mitochondrial NADPH pool may also contribute to the aging process. Therefore pro-longevity therapies should aim to maintain the levels of both NAD⁺ and NADPH in aging tissues.

Targeting Autophagy to Overcome Human Diseases

Autophagy is an evolutionarily conserved cellular process, through which damaged organelles and superfluous proteins are degraded, for maintaining the correct cellular balance during stress insult. It involves formation of double-membrane vesicles, named autophagosomes, that capture cytosolic cargo and deliver it to lysosomes, where the breakdown products are recycled back to cytoplasm. On the basis of degraded cell components, some selective types of autophagy can be identified (mitophagy, ribophagy, reticulophagy, lysophagy, pexophagy, lipophagy, and glycophagy). Dysregulation of autophagy can induce various disease manifestations, such as inflammation, aging, metabolic diseases, neurodegenerative disorders and cancer. The understanding of the molecular mechanism that regulates the different phases of the autophagic process and the role in the development of diseases are only in an early stage. There are still questions that must be answered concerning the functions of the autophagy-related proteins. In this review, we describe the principal cellular and molecular autophagic functions, selective types of autophagy and the main in vitro methods to detect the role of autophagy in the cellular physiology. We also summarize the importance of the autophagic behavior in some diseases to provide a novel insight for target therapies.

Lactobacillus Strains Alleviated Aging Symptoms and Aging-Induced Metabolic Disorders in Aged Rats

Aging is an inevitable and ubiquitous progress that affects all living organisms. A total of 18 strains of lactic acid bacteria (LAB) were evaluated on the activation of adenosine monophosphate-activated protein kinase (AMPK), an intracellular energy sensor mediating lifespan extension. The cell-free supernatant (CFS) of Lactobacillus fermentum DR9 (LF-DR9), Lactobacillus paracasei OFS 0291 (LP-0291), and Lactobacillus helveticus OFS 1515 (LH-1515) showed the highest activation of AMPK and was further evaluated. The phosphorylation of AMPK by these three LAB strains was more evident in U2OS and C2C12 cells, compared to the other cell lines and control (P < .05). Using premature senescent Sprague-Dawley rats induced by D-galactose (D-gal), the administration of LAB (10 log CFU/rat/day) for 12 weeks prevented the shortening of telomere length in D-gal-treated rats compared to the untreated control (P < .05). LF-DR9 lowered gene expression of p53, a known senescent biomarker, in gastrocnemius muscle and tibia compared to the control. The selected LAB strains also enhanced lipid, renal, and liver profile of rats, suggesting added potential of the strains in preventing aging-induced metabolic diseases. Strain LP-0291 and LH-1515 showed ability to adhere to mucin, no antibiotic resistance, tolerated and proliferated under gastric and intestinal simulated conditions, and inhibited the growth of pathogens Escherichia coli, Staphylococcus aureus, and Staphylococcus epidermidis, comparable to commercial probiotic LF-DR9 and Lactobacillus sakei Probio 65. This study provided an insight into the potential of LAB for exhibiting antisenescence effects, with potentials as new medicinal foods for targeted antiaging therapies.

Calorie restriction reprograms diurnal rhythms in protein translation to regulate metabolism

Calorie restriction (CR) delays aging and affects the circadian clocks by reprogramming circadian rhythms in gene expression. To expand on the circadian mechanisms in CR, we assayed rhythms in the protein translation by analyzing polysome-associated mRNAs in the liver of mice fed ad libitum (AL) and CR diets. Global comparison of the diets revealed that <1% of transcripts were differentially abundant in the polysomes. In contrast, the large differential, up to 10%, was detected when CR and AL diets were compared at individual times throughout the day. Most transcripts that were rhythmic under AL lost their rhythms, and many new transcripts gained rhythms under CR. Only a small fraction of transcripts, including the circadian clock genes, were rhythmic under both diets. Thus, CR strongly reprograms translation. CR affected translation of enzymes regulating long-chain acetyl-coenzyme A (Acyl-CoA) metabolism. The expression of the Acyl-CoA thioesterase (ACOT) family was induced upon CR, leading to the increased transcriptional activity of peroxisome proliferator-activated receptor α, the transcriptional factor regulated by the ACOT products. We propose that the differential translation induced by CR leads to a temporal partition and reprogramming of metabolic processes and provides a link between CR, lipid metabolism, and the circadian clock.-Makwana, K., Gosai, N., Poe, A., Kondratov, R. V. Calorie restriction reprograms diurnal rhythms in protein translation to regulate metabolism.

Functional Gut Microbiota Remodeling Contributes to the Caloric Restriction-Induced Metabolic Improvements

Caloric restriction (CR) stimulates development of functional beige fat and extends healthy lifespan. Here we show that compositional and functional changes in the gut microbiota contribute to a number of CR-induced metabolic improvements and promote fat browning. Mechanistically, these effects are linked to a lower expression of the key bacterial enzymes necessary for the lipid A biosynthesis, a critical lipopolysaccharide (LPS) building component. The decreased LPS dictates the tone of the innate immune response during CR, leading to increased eosinophil infiltration and anti-inflammatory macrophage polarization in fat of the CR animals. Genetic and pharmacological suppression of the LPS-TLR4 pathway or transplantation with Tlr4^-/- bone-marrow-derived hematopoietic cells increases beige fat development and ameliorates diet-induced fatty liver, while Tlr4^-/- or microbiota-depleted mice are resistant to further CR-stimulated metabolic alterations. These data reveal signals critical for our understanding of the microbiota-fat signaling axis during CR and provide potential new anti-obesity therapeutics.

Role of AMPK and PPARα in the anti-skin cancer effects of ursolic acid

The phytonutrient ursolic acid (UA), present in apples, rosemary, and other plant sources, has anti-cancer properties in a number of systems, including skin cancers. However, few reports have examined upstream mechanisms by which UA may prevent or treat cancer. Recent reports have indicated UA induces death of cancer cell lines via AMP-activated protein kinase (AMPK), an energy-sensing kinase which possesses both pro-metabolic and anti-cancer effects. Other studies have shown UA activates peroxisome proliferator activated receptor α (PPARα) and the glucocorticoid receptor (GR). Here, we found the cytotoxic effect of UA in skin carcinoma cells required AMPK activation. In addition, two inhibitors of PPARα partially reversed the cytotoxic effects of UA, suggesting its effects are at least partially mediated through this receptor. Finally, inhibition of the GR did not reverse the effects of UA nor did this compound bind the GR under the conditions of experiments performed. Overall, studies elucidating the anti-cancer effects of UA may allow for the development of more potent analogues utilizing similar mechanisms. These studies may also reveal the mediators of any possible side effects or resistance mechanisms to UA therapy.

Role of AMPK signalling pathway during compensatory growth in pigs

Background

The molecular basis of compensatory growth in monogastric animals has not yet been fully explored. Herewith, in this study we aim to determine changes in the pig skeletal muscle transcriptome profile during compensatory growth following a feed restriction period. A RNA-Seq experiment was performed with a total of 24 females belonging to a Duroc commercial line. Half of the animals received either a restricted (RE) or ad libitum (AL) diet during the first fattening period (60–125 d of age). After that, all gilts were fed ad libitum for a further ~30 d until the age of ~155 d, when animals were slaughtered and samples of gluteus medius muscle were harvested to perform RNA-Seq analyses and intramuscular fat content determination.

Results

During the period following food restriction, RE animals re-fed ad libitum displayed compensatory growth, showed better feed conversion rate and tended to deposit more subcutaneous fat than AL fed animals. Animals were slaughtered in the phase of accelerated growth, when RE animals had not completely compensated the performance of AL group, showing lower live and carcass weights. At intramuscular level, RE gilts showed a higher content of polyunsaturated fatty acids during the compensatory growth phase. The comparison of RE and AL expression profiles allowed the identification of 86 (ǀlog₂Fold-Changeǀ > 1, p_adj < 0.05) differentially expressed (DE) genes. A functional categorization of these DE genes identified AMPK Signaling as the most significantly enriched canonical pathway. This kinase plays a key role in the maintenance of energy homeostasis as well as in the activation of autophagy. Among the DE genes identified as components of AMPK Signaling pathway, five out of six genes were downregulated in RE pigs.

Conclusions

Animals re-fed after a restriction period exhibited a less oxidative metabolic profile and catabolic processes in muscle than animals fed ad libitum. The downregulation of autophagy observed in the skeletal muscle of pigs undergoing compensatory growth may constitute a mechanism to increase muscle mass thus ensuring an accelerated growth rate. These results reveal that the downregulation of AMPK Signaling plays an important role in compensatory growth in pigs.

Electronic supplementary material

The online version of this article (10.1186/s12864-018-5071-5) contains supplementary material, which is available to authorized users.

AMP-activated kinase and the endogenous endocannabinoid system might contribute to antinociceptive effects of prolonged moderate caloric restriction in mice

Background

Caloric restriction is associated with broad therapeutic potential in various diseases and an increase in health and life span. In this study, we assessed the impact of caloric restriction on acute and inflammatory nociception in mice, which were either fed ad libitum or subjected to caloric restriction with 80% of the daily average for two weeks.

Results

The behavioral tests revealed that inflammatory nociception in the formalin test and in zymosan-induced mechanical hypersensitivity were significantly decreased when mice underwent caloric restriction. As potential mediators of the diet-induced antinociception, we assessed genes typically induced by inflammatory stimuli, AMP-activated kinase, and the endocannabinoid system which have all already been associated with nociceptive responses. Zymosan-induced inflammatory markers such as COX-2, TNFα, IL-1β, and c-fos in the spinal cord were not altered by caloric restriction. In contrast, AMPKα2 knock-out mice showed significant differences in comparison to C57BL/6 mice and their respective wild type littermates by missing the antinociceptive effects after caloric restriction. Endocannabinoid levels of anandamide and 2-arachidonyl glyceroldetermined in serum by LC-MS/MS were not affected by either caloric restriction alone or in combination with zymosan treatment. However, cannabinoid receptor type 1 expression in the spinal cord, which was not altered by caloric restriction in control mice, was significantly increased after caloric restriction in zymosan-induced paw inflammation. Since increased cannabinoid receptor type 1 signaling might influence AMP-activated kinase activity, we analyzed effects of anandamide on AMP-activated kinase in cell culture and observed a significant activation of AMP-activated kinase. Thus, endocannabionoid-induced AMP-activated kinase activation might be involved in antinociceptive effects after caloric restriction.

Conclusion

Our data suggest that caloric restriction has an impact on inflammatory nociception which might involve AMP-activated kinase activation and an increased activity of the endogenous endocannabinoid system by caloric restriction-induced cannabinoid receptor type 1 upregulation.

The Role of SIRT3 in the Brain Under Physiological and Pathological Conditions

Sirtuin enzymes are a family of highly seven conserved protein deacetylases, namely SIRT1 through SIRT7, whose enzymatic activities require the cofactor nicotinamide adenine dinucleotide (NAD⁺). Sirtuins reside in different compartments within cells, and their activities have been shown to regulate a number of cellular pathways involved in but not limited to stress management, apoptosis and inflammatory responses. Given the importance of mitochondrial functional state in neurodegenerative conditions, the mitochondrial SIRT3 sirtuin, which is the primary deacetylase within mitochondria, has garnered considerable recent attention. It is now clear that SIRT3 plays a major role in regulating a host of mitochondrial molecular cascades that can contribute to both normal and pathophysiological processes. However, most of the currently available knowledge on SIRT3 stems from studies in non-neuronal cells, and the consequences of the interactions between SIRT3 and its targets in the CNS are only beginning to be elucidated. In this review, we will summarize current advances relating to SIRT3, and explore how its known functions could influence brain physiology.

Repeated exposure to heat stress induces mitochondrial adaptation in human skeletal muscle

The heat stress response is associated with several beneficial adaptations that promote cell health and survival. Specifically, in vitro and animal investigations suggest that repeated exposures to a mild heat stress (~40°C) elicit positive mitochondrial adaptations in skeletal muscle comparable to those observed with exercise. To assess whether such adaptations translate to human skeletal muscle, we produced local, deep tissue heating of the vastus lateralis via pulsed shortwave diathermy in 20 men and women ( n = 10 men; n = 10 women). Diathermy increased muscle temperature by 3.9°C within 30 min of application. Immediately following a single 2-h heating session, we observed increased phosphorylation of AMP-activated protein kinase and ERK1/2 but not of p38 MAPK or JNK. Following repeated heat exposures (2 h daily for 6 consecutive days), we observed a significant cellular heat stress response, as heat shock protein 70 and 90 increased 45% and 38%, respectively. In addition, peroxisome proliferator-activated receptor gamma, coactivator-1 alpha and mitochondrial electron transport protein complexes I and V expression were increased after heating. These increases were accompanied by augmentation of maximal coupled and uncoupled respiratory capacity, measured via high-resolution respirometry. Our data provide the first evidence that mitochondrial adaptation can be elicited in human skeletal muscle in response to repeated exposures to mild heat stress. NEW & NOTEWORTHY Heat stress has been shown to elicit mitochondrial adaptations in cell culture and animal research. We used pulsed shortwave diathermy to produce deep tissue heating and explore whether beneficial mitochondrial adaptations would translate to human skeletal muscle in vivo. We report, for the first time, positive mitochondrial adaptations in human skeletal muscle following recurrent heat stress. The results of this study have clinical implications for many conditions characterized by diminished skeletal muscle mitochondrial function.

Stem cell rejuvenation and the role of autophagy in age retardation by caloric restriction: An update

Stem cells being pluripotent in nature can differentiate into a wide array of specific cells and asymmetrically divide to produce new ones but may undergo aging by themselves. Aging has both quantitative and qualitative effects on stem cells, and could eventually restrain them from replenishing into progenitor cells. Reactive oxygen species (ROS) accumulated in the aging cells could not only block the cell cycle but also affect autophagy by damaging the mitochondria. Autophagy could eliminate redundant production of ROS in aging stem cells and helps to maintain the proliferation capacity by restraining the expression of p16^INK4a. Current studies showed that improving autophagy could restore the regenerative ability of aging stem cells. Therefore, it is important for an organism to maintain the appropriate autophagy. Caloric restriction (CR) was shown to retard the stem cell aging by a certain basic level of autophagy, suggesting that CR was an effective way to extend longevity in mammals. However, little is known about the underlying mechanisms. In this review, we tried to explore the molecular mechanisms on how CR induces appropriate autophagy to restore aging stem cell regenerative ability.

Metabolic aspects of neuronal degeneration: From a NAD+ point of view

Cellular metabolism maintains the life of cells, allowing energy production required for building cellular constituents and maintaining homeostasis under constantly changing external environments. Neuronal cells maintain their structure and function for the entire life of organisms and the loss of neurons, with limited neurogenesis in adults, directly causes loss of complexity in the neuronal networks. The nervous system organizes the neurons by placing cell bodies containing nuclei of similar types of neurons in discrete regions. Accordingly, axons must travel great distances to connect different types of neurons and peripheral organs. The enormous surface area of neurons makes them high-energy demanding to keep their membrane potential. Distal axon survival is dependent on axonal transport that is another energy demanding process. All of these factors make metabolic stress a potential risk factor for neuronal death and neuronal degeneration often associated with metabolic diseases. This review discusses recent findings on metabolic dysregulations under neuronal degeneration and pathways protecting neurons in these conditions.

From Religion to Secularism: the Benefits of Fasting

PURPOSE OF REVIEW

Since the early development of human societies, religious beliefs, and practices has been integral to their identity, culture, and social structure, traditions are influenced by the area, era, and culture wherein they developed. Some religions offer advice on behavioral and diet modifications as strategies to fortify the body, purify the spirit, and elevate consciousness. This review is an attempt to compare different practices, describe the health benefits and risks of fasting, and reconcile these age-old recommendations with practical modern life.

RECENT FINDINGS

Research to clarify and quantify the impact of these dietary modifications is challenging due to the variability in recommendations among various religions and in day-to-day practices. Most religions share common goals of well-being, body-mind integration, and spiritual attainment. Historically, the transformational power of fasting periods has been appreciated, but there is still much to discover about the underlying beneficial physiologic mechanisms of fasting in preventing and treating metabolic diseases.

AMP-activated protein kinase activation in mediating phenylalanine-induced neurotoxicity in experimental models of phenylketonuria

Phenylketonuria (PKU), one of the most prevalent autosomal recessive disorders of amino acid metabolism, is characterized by abnormal accumulation of phenylalanine, which can lead to intellectual disability. The main pathologic changes in the central nervous system of untreated phenylketonuric patients are reductions in the number of axons, dendrites, and synapses in the brain. Such alterations are thought to be mainly associated with the toxic effects caused by phenylalanine. However, the underlying molecular mechanisms have not been fully elucidated. The present study shows that a high concentration of phenylalanine remarkably inhibited neuronal neurite formation in vitro. Interestingly, AMP-activated protein kinase (AMPK), the energy status sensor, was activated in cultured cerebral cortical neurons upon phenylalanine treatment. Pretreatment with an AMPK inhibitor ameliorated the reduction of neurite formation caused by phenylalanine. In addition, the levels of the phosphorylated AMPK, the active form of AMPK, were significantly higher in the cerebral cortices of PKU mice with elevated phenylalanine levels in this brain region compared to those in wild-type control mice, whereas the density of dendritic spines on basal secondary dendrites of pyramidal neurons in prefrontal cortices of PKU mice was significantly decreased. Collectively, these findings indicate that AMPK activation is a key event in impaired neuronal dendritic development in PKU and consequently, a potential therapeutic target for developing neuroprotective strategies against phenylalanine-evoked brain injury in PKU.

Protein Restriction, Epigenetic Diet, Intermittent Fasting as New Approaches for Preventing Age-associated Diseases

Data from epidemiological and experimental studies have shown that diet and eating patterns have a major role in the pathogenesis of many age-associated diseases. Since 1935, calorie restriction (CR) has been identified as one of the most effective nongenetic dietary interventions that can increase lifespan. It involves reducing calorie intake by about 20%–40% below ad libitum, without malnutrition. Restricting food intake has been observed to increase lifespan and prevent many age-associated diseases in rats, mice, and many other species. Understanding the metabolic, molecular, and cellular mechanisms involved in the anti-aging effects of CR can help us to find dietary interventions that can mimic its effects. Recently, different studies have shown that intermittent fasting, protein restriction, and an epigenetic diet can have similar effects to those of CR. These approaches were selected because it has been indicated that they act through a similar molecular pathway and also, are safe and effective in delaying or preventing diseases. In this review, we focus on the mechanistic pathway involved in CR. Then, we review the mimicking interventions through the mechanistic approach. For this purpose, we reviewed both animal and human articles, mainly available through the PubMed online database. We then selected the most relevant full texts which are summarized in this article.

Semisynthetic biosensors for mapping cellular concentrations of nicotinamide adenine dinucleotides

We introduce a new class of semisynthetic fluorescent biosensors for the quantification of free nicotinamide adenine dinucleotide (NAD⁺) and ratios of reduced to oxidized nicotinamide adenine dinucleotide phosphate (NADPH/NADP⁺) in live cells. Sensing is based on controlling the spatial proximity of two synthetic fluorophores by binding of NAD(P) to the protein component of the sensor. The sensors possess a large dynamic range, can be excited at long wavelengths, are pH-insensitive, have tunable response range and can be localized in different organelles. Ratios of free NADPH/NADP⁺ are found to be higher in mitochondria compared to those found in the nucleus and the cytosol. By recording free NADPH/NADP⁺ ratios in response to changes in environmental conditions, we observe how cells can react to such changes by adapting metabolic fluxes. Finally, we demonstrate how a comparison of the effect of drugs on cellular NAD(P) levels can be used to probe mechanisms of action.

The role of DNA-PK in aging and energy metabolism

DNA-dependent protein kinase (DNA-PK) is a very large holoenzyme comprised of the p470 kDa DNA-PK catalytic subunit (DNA-PK_cs ) and the Ku heterodimer consisting of the p86 (Ku 80) and p70 (Ku 70) subunits. It is best known for its nonhomologous end joining (NHEJ) activity, which repairs double-strand DNA (dsDNA) breaks (DSBs). As expected, the absence of DNA-PK activity results in sensitivity to ionizing radiation, which generates DSBs and defect in lymphocyte development, which requires NHEJ of the V(D)J region in the immunoglobulin and T-cell receptor loci. DNA-PK also has been reported to have functions seemingly unrelated to NHEJ. For example, DNA-PK responds to insulin signaling to facilitate the conversion of carbohydrates to fatty acids in the liver. More recent evidence indicates that DNA-PK activity increases with age in skeletal muscle, promoting mitochondrial loss and weight gain. These discoveries suggest that our understanding of DNA-PK is far from complete. As many excellent reviews have already been written about the role of DNA-PK in NHEJ, here we will review the non-NHEJ role of DNA-PK with a focus on its role in aging and energy metabolism.

Extranuclear Sirtuins and Metabolic Stress

SIGNIFICANCE

Extranuclear sirtuins in cytosol (SIRT2) and mitochondria (SIRT3, SIRT4, and SIRT5) are key regulators of metabolic enzymes and the antioxidative defense mechanisms. They play an important role in the adjustment of metabolic pathways in alterations of the nutritional status. Recent Advances: Recent studies have shown that in addition to lysine deacetylation, sirtuins catalyze several different lysine deacylation reactions, removal of lipid modifications, and adenosine diphosphate-ribosylation. Large-scale studies have revealed hundreds of target proteins regulated by different sirtuin modifications.

CRITICAL ISSUES

Sensing of the metabolic state and regulation of the sirtuin function and expression are critical components of the machinery, optimizing cellular functions in the switch from fed to fasting condition. Overfeeding, obesity, and metabolic diseases cause metabolic stress that dysregulates the sirtuins, which may play a role in the pathogenesis and complications of metabolic diseases such as type 2 diabetes, fatty liver disease, and cardiac diseases. In the current review, we will discuss the significance of the extranuclear sirtuins as metabolic regulators and in protection against the reactive oxygen species, and also how these sirtuins are regulated by metabolic status and their putative role in metabolic diseases.

FUTURE DIRECTIONS

To efficiently utilize sirtuins as drug targets for treatment of the metabolic diseases, better understanding of the sirtuin functions, targets, regulation, and cross talk is needed. Furthermore, more studies in humans are needed to confirm the many observations mainly made in animal and cell models so far. Antioxid. Redox Signal. 28, 662-676.

TBK1 at the Crossroads of Inflammation and Energy Homeostasis in Adipose Tissue

The noncanonical IKK family member TANK-binding kinase 1 (TBK1) is activated by pro-inflammatory cytokines, but its role in controlling metabolism remains unclear. Here, we report that the kinase uniquely controls energy metabolism. Tbk1 expression is increased in adipocytes of HFD-fed mice. Adipocyte-specific TBK1 knockout (ATKO) attenuates HFD-induced obesity by increasing energy expenditure; further studies show that TBK1 directly inhibits AMPK to repress respiration and increase energy storage. Conversely, activation of AMPK under catabolic conditions can increase TBK1 activity through phosphorylation, mediated by AMPK's downstream target ULK1. Surprisingly, ATKO also exaggerates adipose tissue inflammation and insulin resistance. TBK1 suppresses inflammation by phosphorylating and inducing the degradation of the IKK kinase NIK, thus attenuating NF-κB activity. Moreover, TBK1 mediates the negative impact of AMPK activity on NF-κB activation. These data implicate a unique role for TBK1 in mediating bidirectional crosstalk between energy sensing and inflammatory signaling pathways in both over- and undernutrition.

Insulin-like growth factor receptor signaling regulates working memory, mitochondrial metabolism, and amyloid-β uptake in astrocytes

Objective

A decline in mitochondrial function and biogenesis as well as increased reactive oxygen species (ROS) are important determinants of aging. With advancing age, there is a concomitant reduction in circulating levels of insulin-like growth factor-1 (IGF-1) that is closely associated with neuronal aging and neurodegeneration. In this study, we investigated the effect of the decline in IGF-1 signaling with age on astrocyte mitochondrial metabolism and astrocyte function and its association with learning and memory.

Methods

Learning and memory was assessed using the radial arm water maze in young and old mice as well as tamoxifen-inducible astrocyte-specific knockout of IGFR (GFAP-Cre^TAM/igfr^f/f). The impact of IGF-1 signaling on mitochondrial function was evaluated using primary astrocyte cultures from igfr^f/f mice using AAV-Cre mediated knockdown using Oroboros respirometry and Seahorse assays.

Results

Our results indicate that a reduction in IGF-1 receptor (IGFR) expression with age is associated with decline in hippocampal-dependent learning and increased gliosis. Astrocyte-specific knockout of IGFR also induced impairments in working memory. Using primary astrocyte cultures, we show that reducing IGF-1 signaling via a 30–50% reduction IGFR expression, comparable to the physiological changes in IGF-1 that occur with age, significantly impaired ATP synthesis. IGFR deficient astrocytes also displayed altered mitochondrial structure and function and increased mitochondrial ROS production associated with the induction of an antioxidant response. However, IGFR deficient astrocytes were more sensitive to H₂O₂-induced cytotoxicity. Moreover, IGFR deficient astrocytes also showed significantly impaired glucose and Aβ uptake, both critical functions of astrocytes in the brain.

Conclusions

Regulation of astrocytic mitochondrial function and redox status by IGF-1 is essential to maintain astrocytic function and coordinate hippocampal-dependent spatial learning. Age-related astrocytic dysfunction caused by diminished IGF-1 signaling may contribute to the pathogenesis of Alzheimer's disease and other age-associated cognitive pathologies.

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Altered mitochondrial structure and function with IGFR deficiency in astrocytes is proposed.

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Increased reactive oxygen species production and susceptibility to peroxide induced cytotoxicity.

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Decreased Aβ uptake and impairment in spatial working memory.

Ketone body 3-hydroxybutyrate mimics calorie restriction via the Nrf2 activator, fumarate, in the retina

Calorie restriction (CR) being the most robust dietary intervention provides various health benefits. D-3-hydroxybutyrate (3HB), a major physiological ketone, has been proposed as an important endogenous molecule for CR. To investigate the role of 3HB in CR, we investigated potential shared mechanisms underlying increased retinal 3HB induced by CR and exogenously applied 3HB without CR to protect against ischemic retinal degeneration. The repeated elevation of retinal 3HB, with or without CR, suppressed retinal degeneration. Metabolomic analysis showed that the antioxidant pentose phosphate pathway and its limiting enzyme, glucose-6-phosphate dehydrogenase (G6PD), were concomitantly preserved. Importantly, the upregulation of nuclear factor erythroid 2 p45-related factor 2 (Nrf2), a regulator of G6PD, and elevation of the tricarboxylic acid cycle's Nrf2 activator, fumarate, were also shared. Together, our findings suggest that CR provides retinal antioxidative defense by 3HB through the antioxidant Nrf2 pathway via modification of a tricarboxylic acid cycle intermediate during 3HB metabolism.

Viewpoint: A Contributory Role of Shell Ginger (Alpinia zerumbet (Pers.) B.L. Burtt & R.M. Sm) for Human Longevity in Okinawa, Japan?

The longevity of the population in the Okinawa Islands of Japan has been ascribed to genetic factors and the traditional Okinawa cuisine, which is low in calories and high in plant content. This diet includes shell ginger (Alpinia zerumbet (Pers.) B.L. Burtt &amp; R.M. Sm) of the ginger family (Zingiberaceae). Due to its local popularity, Alpinia zerumbet has become the subject of a good deal of study at the University of the Ryukyus in Okinawa. Personal local experience and review of the literature now suggest that culinary shell ginger may contribute to longevity among the population in Okinawa. This is supported by its abundant phytochemical content, with antioxidant and anti-obesity properties. The major bioactive phytochemicals are dihydro-5,6-dehydrokawain (DDK; 80-410 mg g^-1 fresh weight), 5,6-dehydrokawain (DK; ≤100 mg g^-1), and essential oils, phenols, phenolic acids, and fatty acids (≤150 mg g^-1 each). Further, Alpinia zerumbet extends the lifespan in animals by 22.6%. In conclusion, culinary shell ginger may significantly contribute to human longevity in Okinawa.

A systematic review of p53 regulation of oxidative stress in skeletal muscle

Background: p53 is a tumor suppressor protein involved in regulating a wide array of signaling pathways. The role of p53 in the cell is determined by the type of imposed oxidative stress, its intensity and duration. The last decade of research has unravelled a dual nature in the function of p53 in mediating the oxidative stress burden. However, this is dependent on the specific properties of the applied stress and thus requires further analysis.

Methods: A systematic review was performed following an electronic search of Pubmed, Google Scholar, and ScienceDirect databases. Articles published in the English language between January 1, 1990 and March 1, 2017 were identified and isolated based on the analysis of p53 in skeletal muscle in both animal and cell culture models.

Results: Literature was categorized according to the modality of imposed oxidative stress including exercise, diet modification, exogenous oxidizing agents, tissue manipulation, irradiation, and hypoxia. With low to moderate levels of oxidative stress, p53 is involved in activating pathways that increase time for cell repair, such as cell cycle arrest and autophagy, to enhance cell survival. However, with greater levels of stress intensity and duration, such as with irradiation, hypoxia, and oxidizing agents, the role of p53 switches to facilitate increased cellular stress levels by initiating DNA fragmentation to induce apoptosis, thereby preventing aberrant cell proliferation.

Conclusion: Current evidence confirms that p53 acts as a threshold regulator of cellular homeostasis. Therefore, within each modality, the intensity and duration are parameters of the oxidative stressor that must be analyzed to determine the role p53 plays in regulating signaling pathways to maintain cellular health and function in skeletal muscle.

Abbreviations: Acadl: acyl-CoA dehydrogenase, long chain; Acadm: acyl-CoA dehydrogenase, C-4 to C-12 straight chain; AIF: apoptosis-inducing factor; Akt: protein kinase B (PKB); AMPK: AMP-activated protein kinase; ATF-4: activating transcription factor 4; ATM: ATM serine/threonine kinase; Bax: BCL2 associated X, apoptosis regulator; Bcl-2: B cell Leukemia/Lymphoma 2 apoptosis regulator; Bhlhe40: basic helix-loop-helix family member e40; BH3: Borane; Bim: bcl-2 interacting mediator of cell death; Bok: Bcl-2 related ovarian killer; COX-IV: cytochrome c oxidase IV; cGMP: Cyclic guanosine monophosphate; c-myc: proto-oncogene protein; Cpt1b: carnitine palmitoyltransferase 1B; Dr5: death receptor 5; eNOS: endothelial nitric oxide synthase; ERK: extracellular regulated MAP kinase; Fas: Fas Cell surface death receptor; FDXR: Ferredoxin Reductase; FOXO3a: forkhead box O3; Gadd45a: growth arrest and DNA damage-inducible 45 alpha; GLS2: glutaminase 2; GLUT 1 and 4: glucose transporter 1(endothelial) and 4 (skeletal muscle); GSH: Glutathione; Hes1: hes family bHLH transcription factor 1; Hey1: hes related family bHLH transcription factor with YRPW motif 1; HIFI-α: hypoxia-inducible factor 1, α-subunit; HK2: Hexokinase 2; HSP70: Heat Shock Protein 70; H₂O₂: Hydrogen Peroxide; Id2: inhibitor of DNA-binding 2; IGF-1-BP3: Insulin-like growth factor binding protein 3; IL-1β: Interleukin 1 beta; iNOS: inducible nitric oxide synthase; IRS-1: Insulin receptor substrate 1; JNK: c-Jun N-terminal kinases; LY-83583: 6-anilino-5,8-quinolinedione; inhibitor of soluble guanylate cyclase and of cGMP production; Mdm 2/ 4: Mouse double minute 2 homolog (mouse) Mdm4 (humans); mtDNA: mitochondrial DNA; MURF1: Muscle RING-finger protein-1; MyoD: Myogenic differentiation 1; MyoG: myogenin; Nanog: Nanog homeobox; NF-kB: Nuclear factor-κB; NO: nitric oxide; NoxA: phorbol-12-myristate-13-acetate-induced protein 1 (Pmaip1); NRF-1: nuclear respiratory factor 1; Nrf2: Nuclear factor erythroid 2-related factor 2; P21: Cdkn1a cyclin-dependent kinase inhibitor 1A (P21); P38 MAPK: mitogen-activated protein kinases; p53R2: p53 inducible ribonucleotide reductase gene; P66Shc: src homology 2 domain-containing transforming protein C1; PERP: p53 apoptosis effector related to PMP-22; PGC-1α: Peroxisome proliferator-activated receptor gamma coactivator 1-alpha; PGM: phosphoglucomutase; PI3K: Phosphatidylinositol-4,5-bisphosphate 3-kinase; PKCβ: protein kinase c beta; PTEN: phosphatase and tensin homolog; PTIO: 2-phenyl-4, 4, 5, 5,-tetramethylimidazoline-1-oxyl 3-oxide (PTIO) has been used as a nitric oxide (NO) scavenger; Puma: The p53 upregulated modulator of apoptosis; PW1: paternally expressed 3 (Peg3); RNS: Reactive nitrogen species; SIRT1: sirtuin 1; SCO2: cytochrome c oxidase assembly protein; SOD2: superoxide dismutase 2; Tfam: transcription factor A mitochondrial; TIGAR: Trp53 induced glycolysis repulatory phosphatase; TNF-a: tumor necrosis factor a; TRAF2: TNF receptor associated factor 2; TRAIL: type II transmembrane protein.

Deciphering adipose tissue heterogeneity

Obesity is an excess accumulation of adipose tissue mass, and, together with its sequelae, in particular type II diabetes and metabolic syndrome, obesity presents a major health crisis. Although obesity is simply caused by increased adipose mass, the heterogeneity of adipose tissue in humans means that the response to increased energy balance is highly complex. Individual subjects with similar phenotypes may respond very differently to the same treatments; therefore, obesity may benefit from a personalized precision medicine approach. The variability in the development of obesity is indeed driven by differences in sex, genetics, and environment, but also by the various types of adipose tissue as well as the different cell types that compose it. By describing the distinct cell populations that reside in different fat depots, we can interpret the complex effect of these various players in the maintenance of whole-body energy homeostasis. To further understand adipose tissue, adipogenic differentiation and the transcriptional program of lipid accumulation must be investigated. As the cell- and depot-specific functions are described, they can be placed in the context of energy excess to understand how the heterogeneity of adipose tissue shapes individual metabolic status and condition.

Rhizoma Coptidis and Berberine as a Natural Drug to Combat Aging and Aging-Related Diseases via Anti-Oxidation and AMPK Activation

Aging is the greatest risk factor for human diseases, as it results in cellular growth arrest, impaired tissue function and metabolism, ultimately impacting life span. Two different mechanisms are thought to be primary causes of aging. One is cumulative DNA damage induced by a perpetuating cycle of oxidative stress; the other is nutrient-sensing adenosine monophosphate-activated protein kinase (AMPK) and rapamycin (mTOR)/ ribosomal protein S6 (rpS6) pathways. As the main bioactive component of natural Chinese medicine rhizoma coptidis (RC), berberine has recently been reported to expand life span in Drosophila melanogaster, and attenuate premature cellular senescence. Most components of RC including berberine, coptisine, palmatine, and jatrorrhizine have been found to have beneficial effects on hyperlipidemia, hyperglycemia and hypertension aging-related diseases. The mechanism of these effects involves multiple cellular kinase and signaling pathways, including anti-oxidation, activation of AMPK signaling and its downstream targets, including mTOR/rpS6, Sirtuin1/ forkhead box transcription factor O3 (FOXO3), nuclear factor erythroid-2 related factor-2 (Nrf2), nicotinamide adenine dinucleotide (NAD⁺) and nuclear factor-κB (NF-κB) pathways. Most of these mechanisms converge on AMPK regulation on mitochondrial oxidative stress. Therefore, such evidence supports the possibility that rhizoma coptidis, in particular berberine, is a promising anti-aging natural product, and has pharmaceutical potential in combating aging-related diseases via anti-oxidation and AMPK cellular kinase activation.

Mitochondrial determinants of cancer health disparities

Mitochondria, which are multi-functional, have been implicated in cancer initiation, progression, and metastasis due to metabolic alterations in transformed cells. Mitochondria are involved in the generation of energy, cell growth and differentiation, cellular signaling, cell cycle control, and cell death. To date, the mitochondrial basis of cancer disparities is unknown. The goal of this review is to provide an understanding and a framework of mitochondrial determinants that may contribute to cancer disparities in racially different populations. Due to maternal inheritance and ethnic-based diversity, the mitochondrial genome (mtDNA) contributes to inherited racial disparities. In people of African ancestry, several germline, population-specific haplotype variants in mtDNA as well as depletion of mtDNA have been linked to cancer predisposition and cancer disparities. Indeed, depletion of mtDNA and mutations in mtDNA or nuclear genome (nDNA)-encoded mitochondrial proteins lead to mitochondrial dysfunction and promote resistance to apoptosis, the epithelial-to-mesenchymal transition, and metastatic disease, all of which can contribute to cancer disparity and tumor aggressiveness related to racial disparities. Ethnic differences at the level of expression or genetic variations in nDNA encoding the mitochondrial proteome, including mitochondria-localized mtDNA replication and repair proteins, miRNA, transcription factors, kinases and phosphatases, and tumor suppressors and oncogenes may underlie susceptibility to high-risk and aggressive cancers found in African population and other ethnicities. The mitochondrial retrograde signaling that alters the expression profile of nuclear genes in response to dysfunctional mitochondria is a mechanism for tumorigenesis. In ethnic populations, differences in mitochondrial function may alter the cross talk between mitochondria and the nucleus at epigenetic and genetic levels, which can also contribute to cancer health disparities. Targeting mitochondrial determinants and mitochondrial retrograde signaling could provide a promising strategy for the development of selective anticancer therapy for dealing with cancer disparities. Further, agents that restore mitochondrial function to optimal levels should permit sensitivity to anticancer agents for the treatment of aggressive tumors that occur in racially diverse populations and hence help in reducing racial disparities.

Does eating less make you live longer and better? An update on calorie restriction

The complexity of aging is hard to be captured. However, apart from its tissue-specific features, a structural and functional progressive decline of the whole organism that leads to death, often preceded by a phase of chronic morbidity, characterizes the common process of aging. Therefore, the research goal of scientists in the field moved from the search for strategies able to extend longevity to those ensuring healthy aging associated with a longer lifespan referred to as “healthspan”. The aging process is plastic and can be tuned by multiple mechanisms including dietary and genetic interventions. To date, the most robust approach, efficient in warding off the cellular markers of aging, is calorie restriction (CR). Here, after a preliminary presentation of the major debate originated by CR, we concisely overviewed the recent results of CR treatment on humans. We also provided an update on the molecular mechanisms involved by CR and the effects on some of the age-associated cellular markers. We finally reviewed a number of tested CR mimetics and concluded with an evaluation of future applications of such dietary approach.

Overweight and Obesity Are Predictors of Progression in Early Autosomal Dominant Polycystic Kidney Disease

The association of overweight/obesity with disease progression in patients with autosomal dominant polycystic kidney disease (ADPKD) remains untested. We hypothesized that overweight/obesity associates with faster progression in early-stage ADPKD. Overall, 441 nondiabetic participants with ADPKD and an eGFR>60 ml/min per 1.73 m² who participated in the Halt Progression of Polycystic Kidney Disease Study A were categorized on the basis of body mass index (BMI; calculated using nonkidney and nonliver weight) as normal weight (18.5-24.9 kg/m²; reference; n=192), overweight (25.0-29.9 kg/m²; n=168), or obese (≥30 kg/m²; n=81). We evaluated the longitudinal (5-year) association of overweight/obesity with change in total kidney volume (TKV) by magnetic resonance imaging using linear regression and multinomial logistic regression models. Among participants, mean±SD age was 37±8 years, annual percent change in TKV was 7.4%±5.1%, and BMI was 26.3±4.9 kg/m² The annual percent change in TKV increased with increasing BMI category (normal weight: 6.1%±4.7%, overweight: 7.9%±4.8%, obese: 9.4%±6.2%; P<0.001). In the fully adjusted model, higher BMI associated with greater annual percent change in TKV (β=0.79; 95% confidence interval [95% CI], 0.18 to 1.39, per 5-unit increase in BMI). Overweight and obesity associated with increased odds of annual percent change in TKV ≥7% compared with <5% (overweight: odds ratio, 2.02; 95% CI, 1.15 to 3.56; obese: odds ratio, 3.76; 95% CI, 1.81 to 7.80). Obesity also independently associated with greater eGFR decline (slope) versus normal weight (fully adjusted β =-0.08; 95% CI, -0.15 to -0.02). In conclusion, overweight and, particularly, obesity are strongly and independently associated with rate of progression in early-stage ADPKD.

Downregulation of pathways implicated in liver inflammation and tumorigenesis of glycogen storage disease type Ia mice receiving gene therapy

Glycogen storage disease type Ia (GSD-Ia) is characterized by impaired glucose homeostasis and long-term risks of hepatocellular adenoma (HCA) and carcinoma (HCC). We have shown that the non-tumor-bearing (NT), recombinant adeno-associated virus (rAAV) vector-treated GSD-Ia mice (AAV-NT mice) expressing a wide range (0.9-63%) of normal hepatic glucose-6-phosphatase-α activity maintain glucose homeostasis and display physiologic features mimicking animals living under calorie restriction (CR). We now show that in AAV-NT mice, the signaling pathways of the CR mediators, AMP-activated protein kinase (AMPK) and sirtuin-1 are activated. AMPK/sirtuin-1 inhibit the activity of STAT3 (signal transducer and activator of transcription 3) and NFκB (nuclear factor κB), the pro-inflammatory and cancer-promoting transcription factors. Sirtuin-1 also inhibits cancer metastasis via increasing the expression of E-cadherin, a tumor suppressor, and decreasing the expression of mesenchymal markers. Consistently, in AAV-NT mice, hepatic levels of active STAT3 and NFκB-p65 were reduced as were expression of mesenchymal markers, STAT3 targets, NFκB targets and β-catenin targets, all of which were consistent with the promotion of tumorigenesis. AAV-NT mice also expressed increased levels of E-cadherin and fibroblast growth factor 21 (FGF21), targets of sirtuin-1, and β-klotho, which can acts as a tumor suppressor. Importantly, treating AAV-NT mice with a sirtuin-1 inhibitor markedly reversed many of the observed anti-inflammatory/anti-tumorigenic signaling pathways. In summary, activation of hepatic AMPK/sirtuin-1 and FGF21/β-klotho signaling pathways combined with down-regulation of STAT3/NFκB-mediated inflammatory and tumorigenic signaling pathways can explain the absence of hepatic tumors in AAV-NT mice.