Nutritional regimens with periodically recurring phases of dietary restriction extend lifespan in Drosophila

Recurrent Phases of Strict Protein Limitation Inhibit Tumor Growth and Restore Lifespan in A Drosophila Intestinal Cancer Model

Diets that restrict caloric or protein intake offer a variety of benefits, including decreasing the incidence of cancer. However, whether such diets pose a substantial therapeutic benefit as auxiliary cancer treatments remains unclear. We determined the effects of severe protein depletion on tumorigenesis in a Drosophila melanogaster intestinal tumor model, using a human RAF gain-of-function allele. Severe and continuous protein restriction significantly reduced tumor growth but resulted in premature death. Therefore, we developed a diet in which short periods of severe protein restriction alternated cyclically with periods of complete feeding. This nutritional regime reduced tumor mass, restored gut functionality, and rescued the lifespan of oncogene-expressing flies to the levels observed in healthy flies on a continuous, fully nutritious diet. Furthermore, this diet reduced the chemotherapy-induced stem cell activity associated with tumor recurrence. Transcriptome analysis revealed long-lasting changes in the expression of key genes involved in multiple major developmental signaling pathways. Overall, the data suggest that recurrent severe protein depletion effectively mimics the health benefits of continuous protein restriction, without undesired nutritional shortcomings. This provides seminal insights into the mechanisms of the memory effect required to maintain the positive effects of protein restriction throughout the phases of a full diet. Finally, the repetitive form of strict protein restriction is an ideal strategy for adjuvant cancer therapy that is useful in many tumor contexts.

An aqueous extract of the brown alga Eisenia bicyclis extends lifespan in a sex-specific manner by interfering with the Tor-FoxO axis

Food has a decisive influence on our health, to the extent where even lifespan can be directly affected by it. In the present work, we have examined the effects of an aqueous extract of the marine brown alga Eisenia bicyclis in terms of its potential to extend lifespan. For this purpose, we used the fruit fly Drosophila melanogaster as a model. The experiments showed that small amounts of Eisenia extract can extend lifespan by up to 40%. This effect is not only related to the median but also to the maximum lifespan. Interestingly, this life-extending effect is sex-specific, i.e. it occurs exclusively in females. Even under stressful nutritional conditions such as a high sugar diet, this effect is detectable. Mechanistic studies showed that this life-prolonging effect depends on a functional Tor and a functional FoxO signaling pathway. It can be concluded that components of the Eisenia extract prolong lifespan by interacting with the Tor-FoxO axis. This study may serve to stimulate further investigations, which on the one hand show such a life-prolonging effect also in other organisms and on the other hand identify the substances responsible for this effect. Finally, it may also encourage the increased use of arame as a health-promoting food supplement.

Nutrition, longevity and disease: From molecular mechanisms to interventions

Diet as a whole, encompassing food composition, calorie intake, and the length and frequency of fasting periods, affects the time span in which health and functional capacity are maintained. Here, we analyze aging and nutrition studies in simple organisms, rodents, monkeys, and humans to link longevity to conserved growth and metabolic pathways and outline their role in aging and age-related disease. We focus on feasible nutritional strategies shown to delay aging and/or prevent diseases through epidemiological, model organism, clinical, and centenarian studies and underline the need to avoid malnourishment and frailty. These findings are integrated to define a longevity diet based on a multi-pillar approach adjusted for age and health status to optimize lifespan and healthspan in humans.

Principles of brain aging: Status and challenges of modeling human molecular changes in mice

Due to the extension of human life expectancy, the prevalence of cognitive impairment is rising in the older portion of society. Developing new strategies to delay or attenuate cognitive decline is vital. For this purpose, it is imperative to understand the cellular and molecular events at the basis of brain aging. While several organs are directly accessible to molecular analysis through biopsies, the brain constitutes a notable exception. Most of the molecular studies are performed on postmortem tissues, where cell death and tissue damage have already occurred. Hence, the study of the molecular aspects of cognitive decline largely relies on animal models and in particular on small mammals such as mice. What have we learned from these models? Do these animals recapitulate the changes observed in humans? What should we expect from future mouse studies? In this review we answer these questions by summarizing the state of the research that has addressed cognitive decline in mice from several perspectives, including genetic manipulation and omics strategies. We conclude that, while extremely valuable, mouse models have limitations that can be addressed by the optimal design of future studies and by ensuring that results are cross-validated in the human context.

Low-protein diet applied as part of combination therapy or stand-alone normalizes lifespan and tumor proliferation in a model of intestinal cancer

Tumors of the intestinal tract are among the most common tumor diseases in humans, but, like many other tumor entities, show an unsatisfactory prognosis with a need for effective therapies. To test whether nutritional interventions and a combination with a targeted therapy can effectively cure these cancers, we used the fruit fly Drosophila as a model. In this system, we induced tumors by EGFR overexpression in intestinal stem cells. Limiting the amount of protein in the diet restored life span to that of control animals. In combination with a specific EGFR inhibitor, all major tumor-associated phenotypes could be rescued. This form of treatment was also successful in a real treatment scenario, which means when they started after the full tumor phenotype was expressed. In conclusion, reduced protein administration can be a very promising form of adjuvant cancer therapy.

The control of metabolic traits by octopamine and tyramine in invertebrates

Octopamine (OA) and tyramine (TA) are closely related biogenic monoamines that act as signalling compounds in invertebrates, where they fulfil the roles played by adrenaline and noradrenaline in vertebrates. Just like adrenaline and noradrenaline, OA and TA are extremely pleiotropic substances that regulate a wide variety of processes, including metabolic pathways. However, the role of OA and TA in metabolism has been largely neglected. The principal aim of this Review is to discuss the roles of OA and TA in the control of metabolic processes in invertebrate species. OA and TA regulate essential aspects of invertebrate energy homeostasis by having substantial effects on both energy uptake and energy expenditure. These two monoamines regulate several different factors, such as metabolic rate, physical activity, feeding rate or food choice that have a considerable influence on effective energy intake and all the principal contributors to energy consumption. Thereby, OA and TA regulate both metabolic rate and physical activity. These effects should not be seen as isolated actions of these neuroactive compounds but as part of a comprehensive regulatory system that allows the organism to switch from one physiological state to another.

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

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

A Drosophila model of cigarette smoke induced COPD identifies Nrf2 signaling as an expedient target for intervention

Chronic obstructive pulmonary disease (COPD) is among the most important causes of death. Signaling systems that are relevant for tissue repair and detoxification of reactive oxygen species or xenobiotics are thought to be impaired in lungs of patients suffering from this disease. Here, we developed a simple cigarette smoke induced Drosophila model of COPD based on chronic cigarette smoke exposure that recapitulates major pathological hallmarks of the disease and thus can be used to investigate new therapeutic strategies. Chronic cigarette smoke exposure led to premature death of the animals and induced a set of phenotypes reminiscent of those seen in COPD patients, including reduced physical activity, reduced body fat, increased metabolic rate and a substantial reduction of the respiratory surface. A detailed transcriptomic analysis revealed that especially the TGF-β, Nrf2 and the JAK/STAT signaling pathways are altered by chronic cigarette smoke exposure. Based on these results, we focused on Nrf2 signaling. A pharmacological intervention study performed with oltipraz, an activator of Nrf2 signaling, increased survival of cigarette smoke exposed animals significantly. Thus, the Drosophila COPD model recapitulates many major hallmarks of COPD and it is highly useful to evaluate the potential of alternative therapeutic strategies.

An overview of two decades of diet restriction studies using Drosophila

Dietary restriction (DR) is a potent forerunner in aging studies capable of influencing lifespan and improving health in various model organisms even in their old age. Despite the importance of protein and carbohydrates in the diet (regulation of fecundity and body maintenance respectively), different ratio based combinations of these components has played a major role in lifespan extension studies. In spite of differences existing in dietary protocols across laboratories, diet manipulations have evolved as a major area of research in Drosophila lifespan studies, prominently shedding light on the multi-faceted process over the last two decades. Here, we review various advances and technicalities involved in understanding the DR-mediated lifespan alongside discussing the pros and cons of various existing approaches/diets used across labs. The current review also focuses on the importance of life-stage specific DR implementation and their influence on the life-history traits including lifespan and fecundity, by taking examples of results from different studies comprising diet dilution, calorie restriction, protein restriction, carbohydrate: protein ratios and the modulations in various minor diet components. We thereby intend to gather the major advances made in these fields alongside reviewing the practical implementations that need to be made to get a better view of the DR-mediated lifespan studies.

Sirtuins as Mediator of the Anti-Ageing Effects of Calorie Restriction in Skeletal and Cardiac Muscle

Fighting diseases and controlling the signs of ageing are the major goals of biomedicine. Sirtuins, enzymes with mainly deacetylating activity, could be pivotal targets of novel preventive and therapeutic strategies to reach such aims. Scientific proofs are accumulating in experimental models, but, to a minor extent, also in humans, that the ancient practice of calorie restriction could prove an effective way to prevent several degenerative diseases and to postpone the detrimental signs of ageing. In the present review, we summarize the evidence about the central role of sirtuins in mediating the beneficial effects of calorie restriction in skeletal and cardiac muscle since these tissues are greatly damaged by diseases and advancing years. Moreover, we entertain the possibility that the identification of sirtuin activators that mimic calorie restriction could provide the benefits without the inconvenience of this dietary style.