Better Living through Chemistry: Caloric Restriction (CR) and CR Mimetics Alter Genome Function to Promote Increased Health and Lifespan

How calorie restriction slows aging: an epigenetic perspective

Genomic instability and epigenetic alterations are some of the prominent factors affecting aging. Age-related heterochromatin loss and decreased whole-genome DNA methylation are associated with abnormal gene expression, leading to diseases and genomic instability. Modulation of these epigenetic changes is crucial for preserving genomic integrity and controlling cellular identity is important for slowing the aging process. Numerous studies have shown that caloric restriction is the gold standard for promoting longevity and healthy aging in various species ranging from rodents to primates. It can be inferred that delaying of aging through the main effector such as calorie restriction is involved in cellular identity and epigenetic modification. Thus, an understanding of aging through calorie restriction may seek a more in-depth understanding. In this review, we discuss how caloric restriction promotes longevity and healthy aging through genomic stability and epigenetic alterations. We have also highlighted how the effectors of caloric restriction are involved in modulating the chromatin-based barriers.

An integrative pan-cancer analysis of the molecular characteristics of dietary restriction in tumour microenvironment

BACKGROUND

Dietary restriction (DR), a general term for dieting, has been demonstrated as an effective intervention in reducing the occurrence of cancers. Molecular activities associated with DR are crucial in mediating its anti-cancer effects, yet a comprehensive exploration of the landscape of these activities at the pan-cancer level is still lacking.

METHODS

We proposed a computational approach for quantifying DR-related molecular activities and delineating the landscape of these activities across 33 cancer types and 30 normal tissues within 27,320 samples. We thoroughly examined the associations between DR-related molecular activities and various factors, including the tumour microenvironment, immunological phenotypes, genomic features, and clinical prognosis. Meanwhile, we identified two DR genes that show potential as prognostic predictors in hepatocellular carcinoma and verified them by immunohistochemical assays in 90 patients.

FINDINGS

We found that DR-related molecular activities showed a close association with tumour immunity and hold potential for predicting immunotherapy responses in various cancers. Importantly, a higher level of DR-related molecular activities is associated with improved overall survival and cancer-specific survival. FZD1 and G6PD are two DR genes that serve as biomarkers for predicting the prognosis of patients with hepatocellular carcinoma.

INTERPRETATION

This study presents a robust link between DR-related molecular activities and tumour immunity across multiple cancer types. Our research could open the path for further investigation of DR-related molecular processes in cancer treatment.

FUNDING

National Natural Science Foundation of China (Grant No. 82000628) and the Guangdong-Hong Kong-Macao University Joint Laboratory of Interventional Medicine Foundation of Guangdong Province (Grant No. 2023LSYS001).

The significance of caloric restriction mimetics as anti-aging drugs

Aging is an intricate process characterized by the gradual deterioration of the physiological integrity of a living organism. This unfortunate phenomenon inevitably leads to a decline in functionality and a heightened susceptibility to the ultimate fate of mortality. Therefore, it is of utmost importance to implement interventions that possess the capability to reverse or preempt age-related pathology. Caloric restriction mimetics (CRMs) refer to a class of molecules that have been observed to elicit advantageous outcomes on both health and longevity in various model organisms and human subjects. Notably, these compounds offer a promising alternative to the arduous task of adhering to a caloric restriction diet and mitigate the progression of the aging process and extend the duration of life in laboratory animals and human population. A plethora of molecular signals have been linked to the practice of caloric restriction, encompassing Insulin-like Growth Factor 1 (IGF1), Mammalian Target of Rapamycin (mTOR), the Adenosine Monophosphate-Activated Protein Kinase (AMPK) pathway, and Sirtuins, with particular emphasis on SIRT1. Therefore, this review will center its focus on several compounds that act as CRMs, highlighting their molecular targets, chemical structures, and mechanisms of action. Moreover, this review serves to underscore the significant relationship between post COVID-19 syndrome, antiaging, and importance of utilizing CRMs. This particular endeavor will serve as a comprehensive guide for medicinal chemists and other esteemed researchers, enabling them to meticulously conceive and cultivate novel molecular entities with the potential to function as efficacious antiaging pharmaceutical agents.

Molecular mechanism of caloric restriction mimetics-mediated neuroprotection of age-related neurodegenerative diseases: an emerging therapeutic approach

Aging-induced neurodegenerative diseases (NDs) are significantly increasing health problem worldwide. It has been well documented that oxidative stress is one of the potential causes of aging and age-related NDs. There are no drugs for the treatment of NDs, therefore there is an immediate necessity for the development of strategies/treatments either to prevent or cure age-related NDs. Caloric restriction (CR) and intermittent fasting have been considered as effective strategies in increasing the healthspan and lifespan, but it is difficult to adhere to these routines strictly, which has led to the development of calorie restriction mimetics (CRMs). CRMs are natural compounds that provide similar molecular and biochemical effects of CR, and activate autophagy process. CRMs have been reported to regulate redox signaling by enhancing the antioxidant defense systems through activation of the Nrf2 pathway, and inhibiting ROS generation through attenuation of mitochondrial dysfunction. Moreover, CRMs also regulate redox-sensitive signaling pathways such as the PI3K/Akt and MAPK pathways to promote neuronal cell survival. Here, we discuss the neuroprotective effects of various CRMs at molecular and cellular levels during aging of the brain. The CRMs are envisaged to become a cornerstone of the pharmaceutical arsenal against aging and age-related pathologies.

Effect of Diet and Oxidative Stress in the Pathogenesis of Lymphoproliferative Disorders

Lymphomas are a heterogeneous group of pathologies that result from clonal proliferation of lymphocytes. They are classified into Hodgkin lymphoma and non-Hodgkin lymphoma; the latter develops as a result of B, T, or NK cells undergoing malignant transformation. It is believed that diet can modulate cellular redox state and that oxidative stress is implicated in lymphomagenesis by acting on several biological mechanisms; in fact, oxidative stress can generate a state of chronic inflammation through the activation of various transcription factors, thereby increasing the production of proinflammatory cytokines and causing overstimulation of B lymphocytes in the production of antibodies and possible alterations in cellular DNA. The purpose of our work is to investigate the results of in vitro and in vivo studies on the possible interaction between lymphomas, oxidative stress, and diet. A variety of dietary regimens and substances introduced with the diet that may have antioxidant and antiproliferative effects were assessed. The possibility of using nutraceuticals as novel anticancer agents is discussed; although the use of natural substances in lymphoma therapy is an interesting field of study, further studies are needed to define the efficacy of different nutraceuticals before introducing them into clinical practice.

SIRT1 and SIRT6: The role in aging-related diseases

Aging is characterized by progressive functional deterioration with increased risk of mortality. It is a complex biological process driven by a multitude of intertwined mechanisms such as increased DNA damage, chronic inflammation, and metabolic dysfunction. Sirtuins (SIRTs) are a family of NAD⁺-dependent enzymes that regulate fundamental biological functions from genomic stability and lifespan to energy metabolism and tumorigenesis. Of the seven mammalian SIRT isotypes (SIRT1-7), SIRT1 and SIRT6 are well-recognized for regulating signaling pathways related to aging. Herein, we review the protective role of SIRT1 and SIRT6 in aging-related diseases at molecular, cellular, tissue, and whole-organism levels. We also discuss the therapeutic potential of SIRT1 and SIRT6 modulators in the treatment of these diseases and challenges thereof.

Neurotrophic effects of intermittent fasting, calorie restriction and exercise: a review and annotated bibliography

In the last decades, important progress has been achieved in the understanding of the neurotrophic effects of intermittent fasting (IF), calorie restriction (CR) and exercise. Improved neuroprotection, synaptic plasticity and adult neurogenesis (NSPAN) are essential examples of these neurotrophic effects. The importance in this respect of the metabolic switch from glucose to ketone bodies as cellular fuel has been highlighted. More recently, calorie restriction mimetics (CRMs; resveratrol and other polyphenols in particular) have been investigated thoroughly in relation to NSPAN. In the narrative review sections of this manuscript, recent findings on these essential functions are synthesized and the most important molecules involved are presented. The most researched signaling pathways (PI3K, Akt, mTOR, AMPK, GSK3β, ULK, MAPK, PGC-1α, NF-κB, sirtuins, Notch, Sonic hedgehog and Wnt) and processes (e.g., anti-inflammation, autophagy, apoptosis) that support or thwart neuroprotection, synaptic plasticity and neurogenesis are then briefly presented. This provides an accessible entry point to the literature. In the annotated bibliography section of this contribution, brief summaries are provided of about 30 literature reviews relating to the neurotrophic effects of interest in relation to IF, CR, CRMs and exercise. Most of the selected reviews address these essential functions from the perspective of healthier aging (sometimes discussing epigenetic factors) and the reduction of the risk for neurodegenerative diseases (Alzheimer's disease, Huntington's disease, Parkinson's disease) and depression or the improvement of cognitive function.

Metabolic Silencing via Methionine-Based Amino Acid Restriction in Head and Neck Cancer

In recent years, various forms of caloric restriction (CR) and amino acid or protein restriction (AAR or PR) have shown not only success in preventing age-associated diseases, such as type II diabetes and cardiovascular diseases, but also potential for cancer therapy. These strategies not only reprogram metabolism to low-energy metabolism (LEM), which is disadvantageous for neoplastic cells, but also significantly inhibit proliferation. Head and neck squamous cell carcinoma (HNSCC) is one of the most common tumour types, with over 600,000 new cases diagnosed annually worldwide. With a 5-year survival rate of approximately 55%, the poor prognosis has not improved despite extensive research and new adjuvant therapies. Therefore, for the first time, we analysed the potential of methionine restriction (MetR) in selected HNSCC cell lines. We investigated the influence of MetR on cell proliferation and vitality, the compensation for MetR by homocysteine, the gene regulation of different amino acid transporters, and the influence of cisplatin on cell proliferation in different HNSCC cell lines.

How can we modulate aging through nutrition and physical exercise? An epigenetic approach

The World Health Organization predicts that by 2050, 2.1 billion people worldwide will be over 60 years old, a drastic increase from only 1 billion in 2019. Considering these numbers, strategies to ensure an extended "healthspan" or healthy longevity are urgently needed. The present study approaches the promotion of healthspan from an epigenetic perspective. Epigenetic phenomena are modifiable in response to an individual's environmental exposures, and therefore link an individual's environment to their gene expression pattern. Epigenetic studies demonstrate that aging is associated with decondensation of the chromatin, leading to an altered heterochromatin structure, which promotes the accumulation of errors. In this review, we describe how aging impacts epigenetics and how nutrition and physical exercise can positively impact the aging process, from an epigenetic point of view. Canonical histones are replaced by histone variants, concomitant with an increase in histone post-translational modifications. A slight increase in DNA methylation at promoters has been observed, which represses transcription of previously active genes, in parallel with global genome hypomethylation. Aging is also associated with deregulation of gene expression - usually provided by non-coding RNAs - leading to both the repression of previously transcribed genes and to the transcription of previously repressed genes. Age-associated epigenetic events are less common in individuals with a healthy lifestyle, including balanced nutrition, caloric restriction and physical exercise. Healthy aging is associated with more tightly condensed chromatin, fewer PTMs and greater regulation by ncRNAs.

Effects of Caloric Restriction on Spatial Object Recognition Memory, Hippocampal Neuron Loss and Neuroinflammation in Aged Rats

Age-related neurobiological changes significantly affect hippocampal structure and function, such that the main cognitive impairments associated with aging are related to the integrity of this brain structure, including the deterioration in spatial object recognition (SOR) memory. Previous studies have shown that intrinsic factors such as neuroinflammation, as well as lifestyle factors such as diet, can affect aging-associated brain functions and cognitive performance. In this regard, caloric restriction (CR) produces beneficial effects on health and life expectancy, although its ability to slow down age-dependent effects on cognitive decline and hippocampus (HPC) functioning remains unclear. Therefore, we set out to evaluate the effects of CR on SOR memory in aged male Wistar rats, as well as those on hippocampal neuron loss, neurogenesis and inflammation. The data show that CR in aged rats attenuates the decline in SOR memory, age-associated hippocampal neuron loss, and age-dependent microglial activation. Furthermore, we found a significant reduction in neurogenesis in the dentate gyrus of the old animals relative to adult rats. These findings support the positive effect of CR on SOR memory, suggesting that it dampens hippocampal neuronal loss and reduces proinflammatory activity.

Understanding the Impact of Obesity on Ageing in the Radiance of DNA Metabolism

Ageing is a multi-factorial phenomenon which is considered as a major risk factor for the development of neurodegeneration, osteoporosis, cardiovascular disease, dementia, cancer, and other chronic diseases. Phenotypically, ageing is related with a combination of molecular, cellular, and physiological levels like genomic and epi-genomic alterations, loss of proteostasis, deregulation of cellular and subcellular function and mitochondrial dysfunction. Though, no single molecular mechanism accounts for the functional decline of different organ systems in older humans but accumulation of DNA damage or mutations is a dominant theory which contributes largely to the development of ageing and age-related diseases. However, mechanistic, and hierarchical order of these features of ageing has not been clarified yet. Scientific community now focus on the effect of obesity on accelerated ageing process. Obesity is a complex chronic disease that affects multiple organs and tissues. It can not only lead to various health conditions such as diabetes, cancer, and cardiovascular disease but also can decrease life expectancy which shows similar phenotype of ageing. Higher loads of DNA damage were also observed in the genome of obese people. Thus, inability of DNA damage repair may contribute to both ageing and obesity apart from cancer predisposition. The present review emphasizes on the involvement of molecular phenomenon of DNA metabolism in development of obesity and how it accelerates ageing in mammals.

Impact of Intermittent Fasting on Metabolic Syndrome and Periodontal Disease-A Suggested Preventive Strategy to Reduce the Public Health Burden

Metabolic syndrome (MetS) prevalence continues to climb significantly worldwide in today's ad libitum society. MetS has tremendous societal and economic ramifications, making it imperative to develop effective strategies for preventing and controlling it to alleviate this growing burden. Periodontal disease and MetS are associated with several risk factors. Studies in the past have demonstrated that obesity, cardiovascular illness, and type 2 diabetes mellitus have a negative effect on the severity of the periodontal disease. Patients with metabolic syndrome have elevated serum levels of proinflammatory mediators such as tumor necrosis factor-alpha interleukin-6 and C-reactive protein. Similar inflammatory mediators, such as interleukin-6, tumor necrosis factor-alpha, and C-reactive protein, are increased in patients with severe periodontal disease. Remarkably, intermittent fasting is underpinned by scientific evidence, claiming to be the most effective non-pharmacological, potential therapeutic alternative for combating a wide range of metabolic, inflammatory, and lifestyle-related diseases. Nonetheless, an insufficient investigation has been performed to determine whether intermittent fasting has therapeutic benefits on periodontal inflammation and diseases. Here, we show the interrelationship between metabolic syndrome and periodontal disease and contextualize the beneficial impact of intermittent fasting in modulating the chronic metabolic and periodontal inflammatory response. We also anticipate that this review paves the way for further exploration of intermittent fasting as a unique research paradigm representing a cost-effective alternative strategy to conventional disease management in patients with periodontal diseases and metabolic syndrome which may serve as the foundation for an integrative vision relevant to primary, diagnostic, and therapeutic purposes.

Long-term caloric restriction ameliorates T cell immunosenescence in mice

Aging is associated with a decrease in the function of the immune system, a phenomenon known as immunosenescence, which results in reduced resistance to infection. Caloric restriction (CR) is known to prolong lifespan and to regulate immune function. However, whether and how CR affects immunosenescence remains unclear. Here, we evaluated the effect of long- and short-term CR on immunosenescence by subjecting wild-type mice to CR between 6 and 18 months of age or between 17 and 18 months of age, respectively. Compared with a normal diet or short-term CR, long-term CR induced marked or complete attenuation of age-related decreases in the frequency of spleen NK cells and NKT cells; naïve CD4⁺ and CD8⁺ T cells; and cytokine- and granzyme B-secreting T cells. In contrast, both long- and short-term CR significantly suppressed age-related upregulation of the T cell exhaustion markers PD-1, Tim-3, and KLRG1, as well as the transcription factors NR4A1 and TOX, which regulate the expression of genes associated with the T cell exhaustion phenotype. These results suggest that CR might suppress age-associated immunosenescence by regulating the expression of transcription factors and target genes that control T cell exhaustion.

Pharmacological Approaches to Decelerate Aging: A Promising Path

Biological aging or senescence is a course in which cellular function decreases over a period of time and is a consequence of altered signaling mechanisms that are triggered in stressed cells leading to cell damage. Aging is among the principal risk factors for many chronic illnesses such as cancer, cardiovascular disorders, and neurodegenerative diseases. Taking this into account, targeting fundamental aging mechanisms therapeutically may effectively impact numerous chronic illnesses. Selecting ideal therapeutic options in order to hinder the process of aging and decelerate the progression of age-related diseases is valuable. Along therapeutic options, life style modifications may well render the process of aging. The process of aging is affected by alteration in many cellular and signaling pathways amid which mTOR, SIRT1, and AMPK pathways are the most emphasized. Herein, we have discussed the mechanisms of aging focusing mainly on the mentioned pathways as well as the role of inflammation and autophagy in aging. Moreover, drugs and natural products with antiaging properties are discussed in detail.

Short-term moderate caloric restriction in a high-fat diet alleviates obesity via AMPK/SIRT1 signaling in white adipocytes and liver

Background

Obesity is a growing problem for public health worldwide. Calorie restriction (CR) is a safety and effective life intervention to defend against obesity. Short-term moderate CR may be a more favorable strategy against this pathology. However, the mechanisms behind the effects of CR remain to be clarified. Increased energy expenditure in the liver and brown adipose tissue could potentially be manipulated to modulate and improve metabolism in obesity. Moreover, nicotinamide adenine dinucleotide (NAD)-dependent deacetylase sirtuin-1 (SIRT1) and AMP-activated protein kinase (AMPK) are well-characterized metabolic modulators. We aim to explore the anti-obesity effects of short-term moderate CR by improving energy metabolism via the SIRT1/AMPK pathway in white adipocytes and liver in a mouse model of obesity.

Methods

Male C57BL/6 mice were randomized into two groups receiving either a standard or a high-fat diet (HFD) for 8 weeks to induce obesity. The HFD-induced obese mice were further randomized into two groups: HFD group or CR group (received 75% of the food eaten by HFD group). Their energy metabolism, white adipose tissue (WAT) contents, hepatic fat deposition, the expression of AMPK, SIRT1, peroxisome proliferators γ-activated receptor coactivator-1α (PGC-1α), nuclear factor kappa B (NF-κB), endothelial nitric oxide synthase (eNOS) in WAT, and hepatic tissues were determined.

Results

After 4 weeks, body weight, total serum cholesterol, fasting blood glucose, and insulin levels were significantly lower in the CR group. Moreover, CR ameliorated hepatocyte steatosis, attenuated white adipogenesis, and increased energy expenditure and expressions of SIRT1, PGC-1α, and phosphorylated AMPK in subcutaneous WAT and the hepatic tissues. In addition, CR reduced the protein levels of NF-κB and increased the eNOS expression.

Conclusion

Short-term moderate CR decreases obesity, increases the thermogenesis, and inhibits inflammation in a mouse model of obesity, probably via the activation of the AMPK/SIRT1 pathway in WAT and liver.

An integrated chemo-informatics and in vitro experimental approach repurposes acarbose as a post-ischemic neuro-protectant

The increasing prevalence of ischemic stroke combined with limited therapeutic options highlights the compelling need for continued research into the development of future neuro-therapeutics. Death-Associated Protein Kinase 1 (DAPK1) and p53 protein-protein interaction serve as a signaling point for the convergence of apoptosis and necrosis in cerebral ischemia. In this study, we used an integrated chemo-informatics and in vitro experimental drug repurposing strategy to screen potential small-molecule inhibitors of DAPK1-p53 interaction from the United States of America Food and Drug Administration (FDA) approved drug database exhibiting post-ischemic neuroprotective and neuro-regenerative efficacy and mechanisms. The computational docking and molecular dynamics simulation of FDA-approved drugs followed by an in vitro experimental validation identified acarbose, an anti-diabetic medication and caloric restriction mimetic as a potential inhibitor of DAPK1-p53 interaction. The evaluation of post-ischemic neuroprotective and regenerative efficacy and mechanisms of action for acarbose was carried out using a set of experimental methods, including cell viability, proliferation and differentiation assays, fluorescence staining, and gene expression analysis. Post-ischemic administration of acarbose conferred significant neuroprotection against ischemia-reperfusion injury in vitro. The reduced fluorescence emission in cells stained with _pS²⁰ supported the potential of acarbose in inhibiting the DAPK1-p53 interaction. Acarbose prevented mitochondrial and lysosomal dysfunction, and favorably modulated gene expression related to cell survival, inflammation, and regeneration. BrdU staining and neurite outgrowth assay showed a significant increase in cell proliferation and differentiation in acarbose-treated group. This is the first study known to provide mechanistic insight into the post-ischemic neuroprotective and neuro-regenerative potential of acarbose. Our results provide a strong basis for preclinical studies to evaluate the safety and neuroprotective efficacy of acarbose against ischemic stroke.

SUPPLEMENTARY INFORMATION

The online version contains supplementary material available at 10.1007/s13205-022-03130-5.

Low Energy Status under Methionine Restriction Is Essentially Independent of Proliferation or Cell Contact Inhibition

Nonlimited proliferation is one of the most striking features of neoplastic cells. The basis of cell division is the sufficient presence of mass (amino acids) and energy (ATP and NADH). A sophisticated intracellular network permanently measures the mass and energy levels. Thus, in vivo restrictions in the form of amino acid, protein, or caloric restrictions strongly affect absolute lifespan and age-associated diseases such as cancer. The induction of permanent low energy metabolism (LEM) is essential in this process. The murine cell line L929 responds to methionine restriction (MetR) for a short time period with LEM at the metabolic level defined by a characteristic fingerprint consisting of the molecules acetoacetate, creatine, spermidine, GSSG, UDP-glucose, pantothenate, and ATP. Here, we used mass spectrometry (LC/MS) to investigate the influence of proliferation and contact inhibition on the energy status of cells. Interestingly, the energy status was essentially independent of proliferation or contact inhibition. LC/MS analyses showed that in full medium, the cells maintain active and energetic metabolism for optional proliferation. In contrast, MetR induced LEM independently of proliferation or contact inhibition. These results are important for cell behaviour under MetR and for the optional application of restrictions in cancer therapy.

Machine learning-based predictions of dietary restriction associations across ageing-related genes

BACKGROUND

Dietary restriction (DR) is the most studied pro-longevity intervention; however, a complete understanding of its underlying mechanisms remains elusive, and new research directions may emerge from the identification of novel DR-related genes and DR-related genetic features.

RESULTS

This work used a Machine Learning (ML) approach to classify ageing-related genes as DR-related or NotDR-related using 9 different types of predictive features: PathDIP pathways, two types of features based on KEGG pathways, two types of Protein-Protein Interactions (PPI) features, Gene Ontology (GO) terms, Genotype Tissue Expression (GTEx) expression features, GeneFriends co-expression features and protein sequence descriptors. Our findings suggested that features biased towards curated knowledge (i.e. GO terms and biological pathways), had the greatest predictive power, while unbiased features (mainly gene expression and co-expression data) have the least predictive power. Moreover, a combination of all the feature types diminished the predictive power compared to predictions based on curated knowledge. Feature importance analysis on the two most predictive classifiers mostly corroborated existing knowledge and supported recent findings linking DR to the Nuclear Factor Erythroid 2-Related Factor 2 (NRF2) signalling pathway and G protein-coupled receptors (GPCR). We then used the two strongest combinations of feature type and ML algorithm to predict DR-relatedness among ageing-related genes currently lacking DR-related annotations in the data, resulting in a set of promising candidate DR-related genes (GOT2, GOT1, TSC1, CTH, GCLM, IRS2 and SESN2) whose predicted DR-relatedness remain to be validated in future wet-lab experiments.

CONCLUSIONS

This work demonstrated the strong potential of ML-based techniques to identify DR-associated features as our findings are consistent with literature and recent discoveries. Although the inference of new DR-related mechanistic findings based solely on GO terms and biological pathways was limited due to their knowledge-driven nature, the predictive power of these two features types remained useful as it allowed inferring new promising candidate DR-related genes.

Calorie Restriction for Cancer Prevention and Therapy: Mechanisms, Expectations, and Efficacy

Cancer is one of the most frequently diagnosed diseases, and despite the continuous efforts in searching for new and more effective treatments, its morbidity and mortality remain a significant health problem worldwide. Calorie restriction, a dietary manipulation that consists in a reduction of the calorie intake, is gaining attention as a potential adjuvant intervention for preventing and/or fighting cancer. Several forms of energy reduction intake, which includes caloric restriction tout-court, dietary restrictions, and intermittent fasting, are being explored for their ability to prevent or slow down cancer progression. Additionally, another anti-cancer approach being under investigation relies on the use of nutraceuticals known as “Caloric Restriction Mimetics” that can provide caloric restriction-mediated benefits without subjecting the patients to a strict diet. Preclinical in vitro and in vivo studies consistently show that diet modifiers reducing the calorie have impact on tumor microenvironment and cancer metabolism, resulting in reduced growth and progression of cancer. Preliminary clinical studies show that patients subjected to a reduced nutrient/energy intake experience improved outcomes from chemo- and radiotherapy while better tolerating the side effects. Here, we review the state of the art on the therapeutic potential of calorie restriction and of caloric restriction mimetics in preventing or retarding tumor development by modulating a subset of cellular processes. The most recent clinical progresses with caloric restriction mimetics in the clinical practice are also discussed.

Cysteine Restriction in Murine L929 Fibroblasts as an Alternative Strategy to Methionine Restriction in Cancer Therapy

Methionine restriction (MetR) is an efficient method of amino acid restriction (AR) in cells and organisms that induces low energy metabolism (LEM) similar to caloric restriction (CR). The implementation of MetR as a therapy for cancer or other diseases is not simple since the elimination of a single amino acid in the diet is difficult. However, the in vivo turnover rate of cysteine is usually higher than the rate of intake through food. For this reason, every cell can enzymatically synthesize cysteine from methionine, which enables the use of specific enzymatic inhibitors. In this work, we analysed the potential of cysteine restriction (CysR) in the murine cell line L929. This study determined metabolic fingerprints using mass spectrometry (LC/MS). The profiles were compared with profiles created in an earlier work under MetR. The study was supplemented by proliferation studies using D-amino acid analogues and inhibitors of intracellular cysteine synthesis. CysR showed a proliferation inhibition potential comparable to that of MetR. However, the metabolic footprints differed significantly and showed that CysR does not induce classic LEM at the metabolic level. Nevertheless, CysR offers great potential as an alternative for decisive interventions in general and tumour metabolism at the metabolic level.

Haskap Berry Phenolic Subclasses Differentially Impact Cellular Stress Sensing in Primary and Immortalized Dermal Fibroblasts

It is generally accepted that dietary phenolics from fruits are of significant importance to human health. Unfortunately, there is minimal published data on how differences in phenolic structure(s) impact biological pathways at cellular and molecular levels. We observed that haskap berry extracts isolated with ethanol:formic acid:water or phenolic subclass fractions separated using different concentrations of ethanol (40% and 100%) impacted cell growth in a positive manner. All fractions and extracts significantly increased population doubling times. All extracts and fractions reduced intracellular free radicals; however, there were differences in these effects, indicating different abilities to scavenge free radicals. The extracts and fractions also exhibited differing impacts on transcripts encoding the antioxidant enzymes (CAT, SOD1, GPX1, GSS and HMOX1) and the phosphorylation state of nuclear factor-κB (NF-κB). We further observed that extracts and fractions containing different phenolic structures had divergent impacts on the mammalian target of rapamycin (mTOR) and sirtuin 1 (SIRT1). siRNA-mediated knockdown of SIRT1 transcripts demonstrated that this enzyme is key to eliciting haskap phenolic(s) impact on cells. We postulate that phenolic synergism is of significant importance when evaluating their dietary impact.

Impact of calorie restriction and intermittent fasting on periodontal health

The scientific evidence indicates that calorie restriction and intermittent fasting are among the appropriate strategies targeting factual causative factors of various inflammatory and lifestyle-related disorders. Periodontitis is a common oral inflammatory disease leading to bone loss that is associated with various systemic problems. Previous studies suggest that calorie restriction may dampen inflammation and concomitant tissue damage under inflammatory conditions, such as periodontal diseases in nonhuman primates. However, insufficient research has been carried out to assess the effects of a calorie-restricted diet on the initiation and progression of periodontal disease in humans. This review of the literature aims to describe the general concepts of calorie restriction, its clinical implications, and related therapeutic potential in controlling periodontal inflammation. The review shows that fasting regimen groups have shown lesser bone loss because of an increase in osteoprogenitor cells than non-fasting groups. Calorie restriction dampens the inflammatory response and reduces circulating inflammatory mediators like tumor necrosis factor-alpha, interleukin-6, matrix metalloproteinase-8, matrix metalloproteinase-9, and interleukin-1-beta in gingival crevicular fluid. However, the incorporation of this form of dietary intervention continues to be challenging in our current society, in which obesity is a major public concern. Calorie restriction and intermittent fasting can play a key role in the cost-effective resolution of periodontal inflammation as a primary prevention strategy for the management of chronic inflammatory diseases, including periodontal diseases.

Effects of caloric restriction on monoaminergic neurotransmission, peripheral hormones, and olfactory memory in aged rats

Aging is associated with a reduced ability to identify and discriminate scents, and olfactory dysfunction has been linked to preclinical stages of neurodegenerative diseases in humans. Moreover, emerging evidence suggests that smell-driven behaviors are regulated by hormones like insulin or leptin, and by metabolic parameters like glucose, which in turn may influence monoaminergic neurotransmission in brain areas related to cognition. Several studies have suggested that dietary interventions like caloric restriction (CR) can mitigate the age-induced decline in memory by modifying metabolic parameters and brain monoaminergic levels. The present study explored the effects of CR on age-dependent olfactory memory deficits, as well as their relationship with peripheral leptin, insulin and glucose levels, and brain monoamines. To this end, aged rats (24-months-old) fed on a CR diet or with ad libitum access to food, and adult rats (3-4 months), were trained in an odor discrimination task (ODT). The peripheral plasma levels of insulin, leptin, and glucose, and of monoamines and metabolites/precursors in brain areas related to olfactory learning and memory processes, such as the striatum and frontal cortex (FC), were determined. The data obtained indicated that CR attenuated the age-dependent decline in olfactory sensitivity in old animals fed ad libitum, which was correlated with the performance in ODT retention trial, as well as with leptin plasma levels. CR enhanced dopamine levels in the striatum, while it attenuated the age-related decline in serotonin levels in the striatum and FC. Such findings support a positive effect of CR on age-dependent olfactory sensitivity decline and dysfunctions in brain monoamine levels.

Metabolic Fingerprinting of Murine L929 Fibroblasts as a Cell-Based Tumour Suppressor Model System for Methionine Restriction

Since Otto Warburg reported in 1924 that cancer cells address their increased energy requirement through a massive intake of glucose, the cellular energy level has offered a therapeutic anticancer strategy. Methionine restriction (MetR) is one of the most effective approaches for inducing low-energy metabolism (LEM) due to the central position in metabolism of this amino acid. However, no simple in vitro system for the rapid analysis of MetR is currently available, and this study establishes the murine cell line L929 as such a model system. L929 cells react rapidly and efficiently to MetR, and the analysis of more than 150 different metabolites belonging to different classes (amino acids, urea and tricarboxylic acid cycle (TCA) cycles, carbohydrates, etc.) by liquid chromatography/mass spectrometry (LC/MS) defines a metabolic fingerprint and enables the identification of specific metabolites representing normal or MetR conditions. The system facilitates the rapid and efficient testing of potential cancer therapeutic metabolic targets. To date, MS studies of MetR have been performed using organisms and yeast, and the current LC/MS analysis of the intra- and extracellular metabolites in the murine cell line L929 over a period of 5 days thus provides new insights into the effects of MetR at the cellular metabolic level.

Nutritional Preconditioning in Cancer Treatment in Relation to DNA Damage and Aging

Dietary restriction (DR) is the most successful nutritional intervention for extending lifespan and preserving health in numerous species. Reducing food intake triggers a protective response that shifts energy resources from growth to maintenance and resilience mechanisms. This so-called survival response has been shown to particularly increase life- and health span and decrease DNA damage in DNA repair-deficient mice exhibiting accelerated aging. Accumulation of DNA damage is the main cause of aging, but also of cancer. Moreover, radiotherapies and most chemotherapies are based on damaging DNA, consistent with their ability to induce toxicity and accelerate aging. Since fasting and DR decrease DNA damage and its effects, nutritional preconditioning holds promise for improving (cancer) therapy and preventing short- and long-term side effects of anticancer treatments. This review provides an overview of the link between aging and cancer, highlights important preclinical studies applying such nutritional preconditioning, and summarizes the first clinical trials implementing nutritional preconditioning in cancer treatment.

Dietary Restriction and Oxidative Stress: Friends or Enemies?

Significance: It is well established that lifestyle and dietary habits have a tremendous impact on life span, the rate of aging, and the onset/progression of age-related diseases. Specifically, dietary restriction (DR) and other healthy dietary patterns are usually accompanied by physical activity and differ from Western diet that is rich in fat and sugars. Moreover, as the generation of reactive oxidative species is the major causative factor of aging, while DR could modify the level of oxidative stress, it has been proposed that DR increases both survival and longevity. Recent Advances: Despite the documented links between DR, aging, and oxidative stress, many issues remain to be addressed. For instance, the free radical theory of aging is under "re-evaluation," while DR as a golden standard for prolonging life span and ameliorating the effects of aging is also under debate. Critical Issues: This review article pays special attention to highlight the link between DR and oxidative stress in both aging and age-related diseases. We discuss in particular DR's capability to counteract the consequences of oxidative stress and the molecular mechanisms involved in these processes. Future Directions: Although DR is undoubtedly beneficial, several considerations must be taken into account when designing the best dietary intervention. Use of intermittent fasting, daily food reduction, or DR mimetics? Future research should unravel the pros and cons of all these processes. Antioxid. Redox Signal. 34, 421-438.

Effects of caloric restriction on immunosurveillance, microbiota and cancer cell phenotype: Possible implications for cancer treatment

Fasting, caloric restriction and foods or compounds mimicking the biological effects of caloric restriction, known as caloric restriction mimetics, have been associated with a lower risk of age-related diseases, including cardiovascular diseases, cancer and cognitive decline, and a longer lifespan. Reduced calorie intake has been shown to stimulate cancer immunosurveillance, reducing the migration of immunosuppressive regulatory T cells towards the tumor bulk. Autophagy stimulation via reduction of lysine acetylation, increased sensitivity to chemo- and immunotherapy, along with a reduction of insulin-like growth factor 1 and reactive oxygen species have been described as some of the major effects triggered by caloric restriction. Fasting and caloric restriction have also been shown to beneficially influence gut microbiota composition, modify host metabolism, reduce total cholesterol and triglyceride levels, lower diastolic blood pressure and elevate morning cortisol level, with beneficial modulatory effects on cardiopulmonary fitness, body fat and weight, fatigue and weakness, and general quality of life. Moreover, caloric restriction may reduce the carcinogenic and metastatic potential of cancer stem cells, which are generally considered responsible of tumor formation and relapse. Here, we reviewed in vitro and in vivo studies describing the effects of fasting, caloric restriction and some caloric restriction mimetics on immunosurveillance, gut microbiota, metabolism, and cancer stem cell growth, highlighting the molecular and cellular mechanisms underlying these effects. Additionally, studies on caloric restriction interventions in cancer patients or cancer risk subjects are discussed. Considering the promising effects associated with caloric restriction and caloric restriction mimetics, we think that controlled-randomized large clinical trials are warranted to evaluate the inclusion of these non-pharmacological approaches in clinical practice.

The Nuclear Lamina: Protein Accumulation and Disease

Cellular health is reliant on proteostasis-the maintenance of protein levels regulated through multiple pathways modulating protein synthesis, degradation and clearance. Loss of proteostasis results in serious disease and is associated with aging. One proteinaceous structure underlying the nuclear envelope-the nuclear lamina-coordinates essential processes including DNA repair, genome organization and epigenetic and transcriptional regulation. Loss of proteostasis within the nuclear lamina results in the accumulation of proteins, disrupting these essential functions, either via direct interactions of protein aggregates within the lamina or by altering systems that maintain lamina structure. Here we discuss the links between proteostasis and disease of the nuclear lamina, as well as how manipulating specific proteostatic pathways involved in protein clearance could improve cellular health and prevent/reverse disease.

The Mechanism of Programmed Aging: The Way to Create a Real Remedy for Senescence

BACKGROUND

Accumulation of various damages is considered the primary cause of aging throughout the history of gerontology. No progress has been made in extending animal lifespan under the guidance of this concept. This concept denies the existence of longevity genes, but it has been experimentally shown that manipulating genes that affect cell division rates can increase the maximum lifespan of animals. These methods of prolonging life are unsuitable for humans because of dangerous side effects, but they undoubtedly indicate the programmed nature of aging.

OBJECTIVE

The objective was to understand the mechanism of programmed aging to determine how to solve the problem of longevity.

METHODS

Fundamental research has already explored key details relating to the mechanism of programmed aging, but they are scattered across different fields of knowledge. The way was to recognize and combine them into a uniform mechanism.

RESULTS

Only a decrease in bioenergetics is under direct genetic control. This causes many different harmful processes that serve as the execution mechanism of the aging program. The aging rate and, therefore, lifespan are determined by the rate of cell proliferation and the magnitude of the decrease in bioenergetics per cell division in critical tissues.

CONCLUSION

The mechanism of programmed aging points the way to achieving an unlimited healthy life; it is necessary to develop a means for managing bioenergetics. It has already been substantially studied by molecular biologists and is now waiting for researchers from gerontology.

A nutritional memory effect counteracts benefits of dietary restriction in old mice

Dietary restriction (DR) during adulthood can greatly extend lifespan and improve metabolic health in diverse species. However, whether DR in mammals is still effective when applied for the first time at old age remains elusive. Here, we report results of a late-life DR switch experiment employing 800 mice, in which 24 months old female mice were switched from ad libitum (AL) to DR or vice versa. Strikingly, the switch from DR-to-AL acutely increases mortality, whereas the switch from AL-to-DR causes only a weak and gradual increase in survival, suggesting a memory of earlier nutrition. RNA-seq profiling in liver, brown (BAT) and white adipose tissue (WAT) demonstrate a largely refractory transcriptional and metabolic response to DR after AL feeding in fat tissue, particularly in WAT, and a proinflammatory signature in aged preadipocytes, which is prevented by chronic DR feeding. Our results provide evidence for a nutritional memory as a limiting factor for DR-induced longevity and metabolic remodeling of WAT in mammals.

Epigenetic role of thymoquinone: impact on cellular mechanism and cancer therapeutics

Thymoquinone is a natural product known for its anticancer activity. Preclinical studies indicated numerous mechanisms of action by which thymoquinone exerts its effects on cancer cells. Recent evidence has indicated that thymoquinone can modulate epigenetic machinery, like modifying histone acetylation and deacetylation, DNA methylation and demethylation, which are among the major epigenetic changes that can contribute to carcinogenesis. Moreover, thymoquinone can alter the genetic expression of various noncoding RNAs, such as miRNA and lncRNA, which are the key parts of cellular epigenetics. This review focuses on cellular epigenetic systems, epigenetic changes responsible for cancer and the counteraction of thymoquinone to target epigenetic challenges, which might be among the mechanisms of the thymoquinone effect in cancer cells.

Caloric restriction induces H2O2 formation as a trigger of AMPK-eNOS-NO pathway in obese rats: Role for CAMKII

Caloric restriction (CR) improves endothelial function through the upregulation of adenosine monophosphate-activated protein kinase (AMPK) and endothelial nitric oxide synthase (eNOS). Moreover, hydrogen peroxide (H₂O₂) is upregulated in yeast subjected to CR. Our aim was to assess if mild short-term CR increases vascular H₂O₂ formation as a link with AMPK and eNOS activation. Twelve-week old Zucker obese (fa/fa) and control Zucker lean male rats were fed a standard chow either ad libitum (AL, n=10) or with a 20% CR (CR, n=10) for two weeks. CR significantly improved relaxation to ACh in fa/fa rats because of an enhanced endogenous production of H₂O₂ in aortic rings (H₂O₂ levels _fa/faAL=0.5 ± 0.05 nmol/mg vs. H₂O₂ levels _fa/faCR=0.76 ± 0.07 nmol/mg protein; p<0.05). Expression of mitochondrial superoxide dismutase (Mn-SOD) and total SOD activity were increased in aorta from fa/fa animals after CR. In cultured aortic endothelial cells, serum deprivation or 2-deoxy-d-glucose induced a significant increase in: i) superoxide anion and H₂O₂ levels, ii) p-AMPK/AMPK and p-eNOS/eNOS expression and iii) nitric oxide levels. This effect was reduced by catalase and strongly inhibited by Ca²⁺/calmodulin-dependent kinase II (CamkII) silencing. In conclusion, we propose that mild short-term CR might be a trigger of mechanisms aimed at protecting the vascular wall by the increase of H₂O₂, which then activates AMPK and nitric oxide release, thus improving endothelium-dependent relaxation. In addition, we demonstrate that CAMKII plays a key role in mediating CR-induced AMPK activation through H₂O₂ increase.

Interplay Between the Host, the Human Microbiome, and Drug Metabolism

The human microbiome is composed of four major areas including intestinal, skin, vaginal, and oral microbiomes, with each area containing unique species and unique functionalities. The human microbiome may be modulated with prebiotics, probiotics, and postbiotics to potentially aid in the treatment of diseases like irritable bowel syndrome, bacterial vaginosis, atopic dermatitis, gingivitis, obesity, or cancer. There is also potential for many of the inhabitants of the human microbiome to directly modulate host gene expression and modulate host detoxifying enzyme activity like cytochrome P450s (CYPs), dehydrogenases, and carboxylesterases. Therefore, the microbiome may be important to consider during drug discovery, risk assessment, and dosing regimens for various diseases given that the human microbiome has been shown to impact host detoxification processes.

40th International Asilomar Chromatin, Chromosomes, and Epigenetics Conference

The 40th International Asilomar Chromatin, Chromosomes, and Epigenetics Conference was held in the Asilomar Conference Grounds, Pacific Grove, California, USA, on 6-9 December 2018. The organizing committee consisted of established scientists in the fields of chromatin and epigenetics: Sally Pasion and Michael Goldman from the Biology Department, San Francisco State University, California, USA; Philippe Georgel from the Department of Biological Sciences, Marshal University, West Virginia, USA; Juan Ausió from the Department of Biochemistry and Microbiology, University of Victoria, British Columbia, Canada; and Christopher Eskiw from the Department of Biochemistry, University of Saskatchewan, Saskatchewan, Canada. The meeting had two keynote speakers: Jessica Tyler and Jennifer Mitchell, and it covered topics on transcription, replication and repair, epigenetics, cell differentiation and disease, telomeres, and centromeres and it had two sessions devoted to nuclear and genomic organization. It encompassed the enthusiastic presentations of excellent trainees within the breathtaking natural setting of Pacific Grove.

Metformin induces the AP-1 transcription factor network in normal dermal fibroblasts

Metformin is a widely-used treatment for type 2 diabetes and is reported to extend health and lifespan as a caloric restriction (CR) mimetic. Although the benefits of metformin are well documented, the impact of this compound on the function and organization of the genome in normal tissues is unclear. To explore this impact, primary human fibroblasts were treated in culture with metformin resulting in a significant decrease in cell proliferation without evidence of cell death. Furthermore, metformin induced repositioning of chromosomes 10 and 18 within the nuclear volume indicating altered genome organization. Transcriptome analyses from RNA sequencing datasets revealed that alteration in growth profiles and chromosome positioning occurred concomitantly with changes in gene expression profiles. We further identified that different concentrations of metformin induced different transcript profiles; however, significant enrichment in the activator protein 1 (AP-1) transcription factor network was common between the different treatments. Comparative analyses revealed that metformin induced divergent changes in the transcriptome than that of rapamycin, another proposed mimetic of CR. Promoter analysis and chromatin immunoprecipitation assays of genes that changed expression in response to metformin revealed enrichment of the transcriptional regulator forkhead box O3a (FOXO3a) in normal human fibroblasts, but not of the predicted serum response factor (SRF). Therefore, we have demonstrated that metformin has significant impacts on genome organization and function in normal human fibroblasts, different from those of rapamycin, with FOXO3a likely playing a role in this response.

A rapid, high-throughput method for determining chronological lifespan in budding yeast

The budding yeast Saccharomyces cerevisiae is a major model system in the study of aging. Like metazoans, yeast lifespan is extended by caloric restriction and treatment with pharmacological agents which extend lifespan. A major workhorse of aging research in budding yeast is the chronological lifespan assay. Traditionally, chronological lifespan assays consist of taking regular samples of aging yeast cultures, plating out aliquots on agar, and counting the resulting colonies. This method, while highly reliable, is labor-intensive and expensive in terms of materials consumed. Here, we report a novel MTT-based method for assessing chronological lifespan in yeast. We show that this method is equal to the colony counting method in its rigorous and reliable measurement of lifespan extension in yeast as a result of caloric restriction, and is able to distinguish known long-lived and short-lived yeast strains. We have further developed this method into a high-throughput assay that allows rapid screening of potential anti-aging compounds as well as yeast strains with altered lifespan. Application of this method permits the rapid identification of anti-aging activities in yeast and may facilitate identification of materials with therapeutic potential for higher animals and, most importantly, humans.

Drosophila Gut-A Nexus Between Dietary Restriction and Lifespan

Aging is often defined as the accumulation of damage at the molecular and cellular levels which, over time, results in marked physiological impairments throughout the organism. Dietary restriction (DR) has been recognized as one of the strongest lifespan extending therapies observed in a wide array of organisms. Recent studies aimed at elucidating how DR promotes healthy aging have demonstrated a vital role of the digestive tract in mediating the beneficial effects of DR. Here, we review how dietary restriction influences gut metabolic homeostasis and immune function. Our discussion is focused on studies of the Drosophila digestive tract, where we describe in detail the potential mechanisms in which DR enhances maintenance of the intestinal epithelial barrier, up-regulates lipid metabolic processes, and improves the ability of the gut to deal with damage or stress. We also examine evidence of a tissue-tissue crosstalk between gut and neighboring organs including brain and fat body. Taken together, we argue that the Drosophila gut plays a critical role in DR-mediated lifespan extension.

Epigenetic Drift Is a Determinant of Mammalian Lifespan

The epigenome, which controls cell identity and function, is not maintained with 100% fidelity in somatic animal cells. Errors in the maintenance of the epigenome lead to epigenetic drift, an important hallmark of aging. Numerous studies have described DNA methylation clocks that correlate epigenetic drift with increasing age. The question of how significant a role epigenetic drift plays in creating the phenotypes associated with aging remains open. A recent study describes a new DNA methylation clock that can be slowed by caloric restriction (CR) in a way that correlates with the degree of lifespan and healthspan extension conferred by CR, suggesting that epigenetic drift itself is a determinant of mammalian lifespan. Genetic transplantation using genomic editing of DNA methylation homeostatic genes from long-lived to short-lived species is one way to potentially demonstrate a causative role for DNA methylation. Whether the DNA methylation clock be reset to youthful state, eliminating the effects of epigenetic drift without requiring a pluripotent cell intermediate is a critical question with profound implications for the development of aging therapeutics. Methods that transiently erase the DNA methylation pattern of somatic cells may be developed that reset this aging hallmark with potentially profound effects on lifespan, if DNA methylation-based epigenetic drift really plays a primary role in aging.

Plasticity of lifelong calorie-restricted C57BL/6J mice in adapting to a medium-fat diet intervention at old age

Calorie restriction (CR) is a dietary regimen that supports healthy aging. In this study, we investigated the systemic and liver‐specific responses caused by a diet switch to a medium‐fat (MF) diet in 24‐month‐old lifelong, CR‐exposed mice. This study aimed to increase the knowledge base on dietary alterations of gerontological relevance. Nine‐week‐old C57BL/6J mice were exposed either to a control, CR, or MF diet. At the age of 24 months, a subset of mice of the CR group was transferred to ad libitumMF feeding (CR‐MF). The mice were sacrificed at the age of 28 months, and then, biochemical and molecular analyses were performed. Our results showed that, despite the long‐term exposure to the CR regimen, mice in the CR‐MF group displayed hyperphagia, rapid weight gain, and hepatic steatosis. However, no hepatic fibrosis/injury or alteration in CR‐improved survival was observed in the diet switch group. The liver transcriptomic profile of CR‐MF mice largely shifted to a profile similar to the MF‐fed animals but leaving ~22% of the 1,578 differentially regulated genes between the CR and MF diet groups comparable with the expression of the lifelong CR group. Therefore, although the diet switch was performed at an old age, the CR‐MF‐exposed mice showed plasticity in coping with the challenge of a MF diet without developing severe liver pathologies.

Drug Discovery in Fish, Flies, and Worms

Nonmammalian model organisms such as the nematode Caenorhabditis elegans, the fruit fly Drosophila melanogaster, and the zebrafish Danio rerio provide numerous experimental advantages for drug discovery including genetic and molecular tractability, amenability to high-throughput screening methods and reduced experimental costs and increased experimental throughput compared to traditional mammalian models. An interdisciplinary approach that strategically combines the study of nonmammalian and mammalian animal models with diverse experimental tools has and will continue to provide deep molecular and genetic understanding of human disease and will significantly enhance the discovery and application of new therapies to treat those diseases. This review will provide an overview of C. elegans, Drosophila, and zebrafish biology and husbandry and will discuss how these models are being used for phenotype-based drug screening and for identification of drug targets and mechanisms of action. The review will also describe how these and other nonmammalian model organisms are uniquely suited for the discovery of drug-based regenerative medicine therapies.

Metformin reduces all-cause mortality and diseases of ageing independent of its effect on diabetes control: A systematic review and meta-analysis

This systematic review investigated whether the insulin sensitiser metformin has a geroprotective effect in humans. Pubmed and Embase were searched along with databases of unpublished studies. Eligible research investigated the effect of metformin on all-cause mortality or diseases of ageing relative to non-diabetic populations or diabetics receiving other therapies with adjustment for disease control achieved. Overall, 260 full-texts were reviewed and 53 met the inclusion criteria. Diabetics taking metformin had significantly lower all-cause mortality than non-diabetics (hazard ratio (HR)=0.93, 95%CI 0.88-0.99), as did diabetics taking metformin compared to diabetics receiving non-metformin therapies (HR=0.72, 95%CI 0.65-0.80), insulin (HR=0.68, 95%CI 0.63-0.75) or sulphonylurea (HR=0.80, 95%CI 0.66-0.97). Metformin users also had reduced cancer compared to non-diabetics (rate ratio=0.94, 95%CI 0.92-0.97) and cardiovascular disease (CVD) compared to diabetics receiving non-metformin therapies (HR=0.76, 95%CI 0.66-0.87) or insulin (HR=0.78, 95%CI 0.73-0.83). Differences in baseline characteristics were observed which had the potential to bias findings, although statistical adjustments were made. The apparent reductions in all-cause mortality and diseases of ageing associated with metformin use suggest that metformin could be extending life and healthspans by acting as a geroprotective agent.

Dietary restriction protects from age-associated DNA methylation and induces epigenetic reprogramming of lipid metabolism

Background

Dietary restriction (DR), a reduction in food intake without malnutrition, increases most aspects of health during aging and extends lifespan in diverse species, including rodents. However, the mechanisms by which DR interacts with the aging process to improve health in old age are poorly understood. DNA methylation could play an important role in mediating the effects of DR because it is sensitive to the effects of nutrition and can affect gene expression memory over time.

Results

Here, we profile genome-wide changes in DNA methylation, gene expression and lipidomics in response to DR and aging in female mouse liver. DR is generally strongly protective against age-related changes in DNA methylation. During aging with DR, DNA methylation becomes targeted to gene bodies and is associated with reduced gene expression, particularly of genes involved in lipid metabolism. The lipid profile of the livers of DR mice is correspondingly shifted towards lowered triglyceride content and shorter chain length of triglyceride-associated fatty acids, and these effects become more pronounced with age.

Conclusions

Our results indicate that DR remodels genome-wide patterns of DNA methylation so that age-related changes are profoundly delayed, while changes at loci involved in lipid metabolism affect gene expression and the resulting lipid profile.

Electronic supplementary material

The online version of this article (doi:10.1186/s13059-017-1187-1) contains supplementary material, which is available to authorized users.

Roles of estrogen receptor-alpha in mediating life span: the hypothalamic deregulation hypothesis

In several species caloric restriction (CR) extends life span. In this paper we integrate data from studies on CR and other sources to articulate the hypothalamic deregulation hypothesis by which estrogen receptor-alpha (ER-α) signaling in the hypothalamus and limbic system affects life span under the stress of CR in mammals. ER-α is one of two principal estrogen-binding receptors differentially expressed in the amygdala, hippocampus, and several key hypothalamic nuclei: the arcuate nucleus (ARN), preoptic area (POA), ventromedial nucleus (VMN), antero ventral periventricular nucleus (AVPV), paraventricular nucleus (PVN), supraoptic nucleus (SON), and suprachiasmatic nucleus (SCN). Estradiol signaling via ER-α is essential in basal level functioning of reproductive cycle, sexually receptive behaviors, physiological stress responses, as well as sleep cycle, and other nonsexual behaviors. When an organism is placed under long-term CR, which introduces an external stress to this ER-α signaling, the reduction of ER-α expression is attenuated over time in the hypothalamus. This review paper seeks to characterize the downstream effects of ER-α in the hypothalamus and limbic system that affect normal endocrine functioning.