Project description:The beneficial effects of dietary restriction (DR) are associated with a rearrangement of gene expression that modulate metabolic and cytoprotective pathways. However, the effect of DR on the cerebellar transcriptome remained to be fully defined. Therefore we analyzed the effect of 30% DR on the transcriptome of cerebellar cortex of young-adult male mice using RNAseq.
Project description:Dietary restriction is a nutritional intervention that consistently increases life span in animals. To identify alternative, more acceptable nutritional regimes that nevertheless extend life span, we used the fruit fly Drosophila melanogaster as a model. We tested if weekly recurring nutritional regimes composed of phases of ad libitum feeding and dietary restriction can increase life span. Short periods of dietary restriction (up to 2 days) followed by longer ad libitum phases increased life span only marginally, whereas regimes comprising longer contiguous periods (3 days and more) became clearly positive, reaching similar life span extensions as those seen if dietary restriction was applied persistently. Female flies were substantially more responsive to these interventions than males. The finding that a minimal period of 3-4 days of dietary restriction is required to induce robust life span extensions was mirrored by the observation that substantial physiological and transcriptional changes occurred in a similar temporal pattern. Moreover, these dietary restriction induced changes were also detectable after switching to ad libitum feeding. Among the physiological changes induced by these phases of dietary restriction, a reduced metabolic rate and a substantial and long-lasting reduction in insulin signaling were most compelling. Age associated molecular signatures comprising mechanisms that reduce insulin signaling showed up after longer periods of dietary restriction in the fly’s fat body, thus showing how molecular alterations transduce into life span related physiological changes.
Project description:BackgroundDietary restriction (DR) is a well-established universal anti-aging intervention, and is neuroprotective in multiple models of nervous system disease, including models with cerebellar pathology. The beneficial effects of DR are associated with a rearrangement of gene expression that modulate metabolic and cytoprotective pathways. However, the effect of DR on the cerebellar transcriptome remained to be fully defined.ResultsHere we analyzed the effect of a classical 30% DR protocol on the transcriptome of cerebellar cortex of young-adult male mice using RNAseq. We found that about 5% of expressed genes were differentially expressed in DR cerebellum, the far majority of whom showing subtle expression changes. A large proportion of down-regulated genes are implicated in signaling pathways, in particular pathways associated with neuronal signaling. DR up regulated pathways in large part were associated with cytoprotection and DNA repair. Analysis of the expression of cell-specific gene sets, indicated a strong enrichment of DR down genes in Purkinje cells, while genes specifically associated with granule cells did not show such a preferential down-regulation.ConclusionOur data show that DR may have a clear effect on the cerebellar transcriptome inducing a mild shift from physiology towards maintenance and repair, and having cell-type specific effects.
Project description:The small intestine is responsible for nutrient absorption and it is one of the most important interfaces between the environment and our body. During aging, changes in the structure of the epithelium lead to food malabsorption and reduced barrier function thus increasing disease risk in aging. The molecular drivers of these alterations remain poorly understood. Here, we compared the proteomes of small intestinal crypts from mice across different anatomical regions and age groups. We found that aging alters epithelial immune responses, metabolic networks and stem cell proliferation, and it is accompanied by a region-dependent skewing in the cellular composition of the intestinal epithelium. Of note, a short period of dietary restriction followed by re-feeding partially restores the epithelium to a youthful state by promoting the differentiation of intestinal stem cells (ISCs) towards the secretory lineage. Using in vitro and in vivo studies, we identify Hmgcs2 (3-hydroxy-3-methylglutaryl-CoA synthetase 2) – the rate limiting enzyme in the synthesis of ketone bodies – as a modulator of ISCs differentiation, which responds to dietary changes. This study provides an atlas of age-dependent proteome changes in defined regions of the intestinal epithelium and characterizes how young and old mice adapt to drastic changes of diet, such as dietary restriction and re-feeding.
Project description:Dietary restriction (DR) is the most effective and reproducible intervention to extend lifespan in divergent species1. In mammals, two regimens of DR, intermittent fasting (IF) and caloric restriction (CR), have proven to extend lifespan and reduce the incidence of age-related disorders2. An important characteristic of IF is that it can increase lifespan, even when there is little or no overall decrease in calorie intake2. The molecular mechanisms underlying IF-induced longevity, however, remain largely unknown. Here we establish an IF regimen that effectively extends the lifespan of Caenorhabditis elegans, and show that a nutrient-related signalling molecule, the low molecular weight GTPase Cel-Rheb, has a dual role in lifespan regulation; Cel-Rheb is required for the IF-induced longevity, whereas inhibition of Cel-Rheb mimics the CR effects. We also show that Cel-Rheb exerts its effects in part via the insulin/IGF-like signalling effector DAF-16 in IF, and that Cel-Rheb is required for fasting-induced nuclear translocation of DAF-16. We find that HSP-12.6, a DAF-16 target, functions to mediate the IF-induced longevity. Furthermore, our analyses demonstrate that most of fasting-induced upregulated genes require Cel-Rheb function for their induction, and that Cel-Rheb/Cel-TOR signalling is required for the fasting-induced downregulation of an insulin-like peptide, INS-7. These findings identify the essential role of signalling via Cel-Rheb in IF-induced longevity and gene expression changes, and suggest a molecular link between the IF-induced longevity and the insulin/IGF-like signalling pathway.
Project description:The cerebellum harbors a circadian clock that can be shifted by scheduled mealtime and participates in behavioral anticipation of food access. To determine which cerebellar proteins are modified by time-of-day and/or feeding time, we determined day-night variations of proteome in the cerebellum of mice fed either ad libitum or only during daytime (from noon to lights off). Two-dimensional differences in gel electrophoresis (2D-DIGE) combined with two-way analyses of variance reveals that a majority of cerebellar proteins are significantly regulated by feeding conditions (food availability). Levels of few other cerebellar proteins were modulated exclusively by daily (or circadian) cues, independent of meal time, and others due to combined influence of meal time and time-of-day. Changes reflect behavioral anticipation of mealtime and/or feeding-induced shift in the circadian clock of the cerebellum.
Project description:Dietary restriction (DR) is the most powerful natural means to extend lifespan. Here we obtain temporally resolved transcriptomes during calorie restriction and intermittent fasting in Caenorhabditis elegans, and find that early and late responses involve metabolism and cell cycle/DNA damage, respectively.
Project description:Dietary protein dilution (DPD) promotes metabolic remodelling and health but the precise nutritional components driving this response remain elusive. Here we demonstrate that dietary amino acids (AA) are sufficient and necessary to drive the response to DPD. In particular, the restriction of dietary essential AA (EAA) supply, but not non-EAA, drives the systemic metabolic response to total AA deprivation. Furthermore, systemic deprivation of Thr and Trp, independent of total AA supply, are both adequate and necessary to confer the systemic metabolic response to both diet, and genetic AA-transport loss, driven AA restriction. Thr is also potentially limiting in low-protein diet fed humans, and dietary Thr restriction (DTR) retarded the development of obesity-associated metabolic dysfunction in mice. Liver-derived fibroblast growth factor 21 was required for the metabolic remodelling with DTR. Strikingly, hepatocyte-selective establishment of Thr biosynthetic capacity reversed the systemic response to DTR. Taken together, our studies demonstrate that the restriction of EAA are sufficient and necessary to confer the systemic metabolic effects of DPD.
Project description:Cysteine is a semi-essential amino acid provided by dietary intake of mainly meat, eggs and whole grains or via the amino acid methionine. The majority of dietary cystine is absorbed in the small intestine and can be used for protein synthesis or converted to taurine and glutathione. Since there is a trend towards adopting a vegetarian/vegan diet, which is low in cysteine, in this study, we investigate the effect of dietary cystine restriction on intestinal epithelial layer function. Mice (8/group) received a normal diet or a diet low in cystine for 2 weeks. We observed no changes in plasma methionine, cysteine, taurine or glutathione levels after 2 weeks. Stem cell markers as well as the proliferation marker Ki67 were or tended to be increased upon cystine restriction. Gene set enrichment analysis reveals enrichment of Wnt signaling in the small intestine of mice on the low cystine diet. These proliferative effects were not observed in the colon, and are thus specific for the small intestine. In the colon, we observed that dietary cystine restriction results in an increase in the number of goblet cells but no significant changes in the thickness of the mucus barrier or in its protective capacity. There was no difference in the microbiome between the normal and low cystine diet. Overall, we cannot conclude if dietary cystine restriction is beneficial, since increased proliferation and goblet cells can indicate a potential for damage repair, nevertheless hyperproliferation has the potential to induce cancer as well.
Project description:Aims/hypothesis: Dietary restriction (DR) reduces adiposity and improves metabolism in patients with one or more symptoms of the metabolic syndrome. Nonetheless, it remains elusive whether the benefits of DR in humans are mediated by calorie or nutrient restriction. This study was conducted to identify whether isocaloric dietary protein restriction is sufficient to confer the beneficial effects of dietary restriction in patients with metabolic syndrome. Methods: We performed a prospective, randomized controlled dietary intervention under constant nutritional and medical supervision. A total of 21 individuals diagnosed with the metabolic syndrome was randomly assigned for caloric restriction (CR; n = 11, mean age 49 ± 8.5 years, female 63%; diet of 5,941 ± 686 KJ per day) or isocaloric dietary protein restriction (PR; n = 10, mean age 51.6 ± 8.9 years, female 50%; diet of 8,409 ± 2,360 KJ per day) and followed for 27 days. Results: Like CR, PR promoted weight loss (-6.6%, P= 0.0041) due to reduction in adiposity (-9.9%, P= 0.0007), associated with reductions in blood glucose (-52.7%, P= 0.0002), lipid levels (cholesterol, -35.4%, P= 0.0010; triglycerides, -39.5% P= 0.0022) and blood pressure (systolic, -37.7 P< 0.0001; diastolic, -73.2% P< 0.0001). PR resulted in enrichment of metabolic pathways related to the immune system such as B cell proliferation, lymphocyte proliferation and leukocyte proliferation in subcutaneous adipose tissue. Hence, a reduction in calorie intake or changes in the gut microbiome are not necessary to confer the metabolic benefits of DR. Instead, a reduction in protein intake with a mild increase in carbohydrate intake to maintain the isocaloric balance of the diet is sufficient to improve metabolic control. Conclusions/interpretation: Protein restriction is sufficient to confer almost the same clinical outcomes as calorie restriction without the need for a reduction in calorie intake. The isocaloric characteristic of the PR intervention makes this approach a more attractive and less drastic dietary strategy in clinical settings and has greater potential to be used as adjuvant therapy for people with the metabolic syndrome.