Project description:Adequate protein intake is crucial for animals. Despite the recent progress in understanding protein hunger and satiety in the fruit fly Drosophila melanogaster, how fruit flies assess prospective dietary protein sources and ensure protein consumption remains elusive. We show here that three specific amino acids, L-glutamate (L-Glu), L-alanine (L-Ala), and L-aspartate (L-Asp), but not the D-enantiomers, rapidly promote food consumption in fruit flies when present in food. The effect of dietary amino acids to promote food consumption is independent of mating experience and internal nutritional status. Calcium imaging experiments show that six brain neurons expressing diuretic hormone 44 (DH44) can be rapidly and directly activated by these three amino acids during feeding. Genetic analysis shows that DH44+ neurons are both necessary and sufficient for dietary amino acids to promote food consumption. By conducting single cell RNAseq analysis, we also identify a amino acid transporter, CG13248, which is highly expressed in DH44+ neurons and is required for dietary amino acids to promote food consumption. Therefore, these data suggest that dietary amino acids may enter DH44+ neurons via CG13248 and modulate their activity and hence food consumption. Taken together, these data identify an internal amino acid sensor in the fly brain that evaluate food sources post-ingestively and facilitates adequate protein intake. These results shed critical light on the regulation of protein homeostasis at organismal levels by the nervous system.
Project description:Time-restricted feeding improves metabolic health independently of dietary macronutrient composition or energy restriction. To understand the mechanisms underpinning the effects of time-restricted feeding, we investigated the metabolic and transcriptomic profile of skeletal muscle and serum samples from 11 overweight/obese men. In muscle, 4-10% of transcripts and 14% of metabolites were periodic, with the amplitude of the metabolites lower after time-restricted feeding. Core clock genes were unaltered by either intervention, while time-restricted feeding induced rhythmicity of genes related to lipid and amino acid transport. In serum, 49-65% of the metabolites had diurnal rhythms across both conditions, with the majority being lipids. Time-restricted feeding shifted the skeletal muscle metabolite profile from predominantly lipids to amino acids. Our results show time-restricted feeding differentially affects the amplitudes and rhythmicity of serum and skeletal muscle metabolites, and regulates the rhythmicity of genes controlling lipid and amino acid transport, without perturbing the core clock.
Project description:Postoperative insulin resistance refers to the phenomenon that the body’s glucose uptake stimulated by insulin is reduced due to stress effects such as trauma or the inhibitory effect of insulin on liver glucose output is weakened after surgery.
There is a clear link between postoperative insulin resistance and poor perioperative prognosis. Therefore, exploring interventions to reduce postoperative stress insulin resistance, stabilize postoperative blood glucose, and reduce postoperative complications are clinical problems that need to be solved urgently. In recent years, research on branched-chain amino acids and metabolic diseases has become a hot spot. Studies have found that in the rat model, preoperatively given a high branched-chain amino acid diet can inhibit postoperative insulin resistance and stabilize blood glucose levels. This research plan is to try to add branched-chain amino acids before surgery to observe the occurrence of postoperative insulin resistance in patients.
Project description:Elevated branched chain amino acids (BCAAs) are associated with obesity and insulin resistance. How long-term dietary BCAAs impact late-life health and lifespan is unknown. Here, we show that when dietary BCAAs are varied against a fixed, isocaloric macronutrient background, long-term exposure to high BCAA diets led to hyperphagia, obesity and reduced lifespan. These effects were not due to elevated BCAA per se or hepatic mTOR activation, but rather the shift in balance between dietary BCAAs and other AAs, notably tryptophan and threonine. Increasing the ratio of BCAAs to these AAs resulted in hyperphagia and was linked to central serotonin depletion. Preventing hyperphagia by calorie restriction or pair-feeding averted the health costs of a high BCAA diet. Our data highlight a role for amino acid quality in energy balance and show that health costs of chronic high BCAA intakes were not due to intrinsic toxicity; rather, to hyperphagia driven by AA imbalance.
Project description:The majority of breast tumours express oestrogen receptor (ER) and receive endocrine therapy (ET) as standard care. Despite its efficacy, ~40% of women relapse with endocrine therapy-resistant (ETR) disease. A global transcription analysis and subsequent integrative approaches of ETR cells showed a deregulated node between miR-23b-3p and the amino acids transporter SLC6A14. Mechanistic analysis supports a model in which such deregulation impairs amino acids metabolism in the ETR cells with subsequent activation of autophagy and enhanced aspartate and glutamate import mediated by the SLC1A2 transporter. The clinical significance of these findings was validated by multiple orthogonal approaches in a large cohort of ET-treated patients, in patient-derived xenografts and in in vivo experiments. Targeting such reprogramming impairs the aggressive features of ETR cells and offers predictive biomarkers and potential targetable pathways to be exploited to combat or delay ETR in ER positive breast cancers.
Project description:The majority of breast tumours express oestrogen receptor (ER) and receive endocrine therapy (ET) as standard care. Despite its efficacy, ~40% of women relapse with endocrine therapy-resistant (ETR) disease. A global transcription analysis and subsequent integrative approaches of ETR cells showed a deregulated node between miR-23b-3p and the amino acids transporter SLC6A14. Mechanistic analysis supports a model in which such deregulation impairs amino acids metabolism in the ETR cells with subsequent activation of autophagy and enhanced aspartate and glutamate import mediated by the SLC1A2 transporter. The clinical significance of these findings was validated by multiple orthogonal approaches in a large cohort of ET-treated patients, in patient-derived xenografts and in in vivo experiments. Targeting such reprogramming impairs the aggressive features of ETR cells and offers predictive biomarkers and potential targetable pathways to be exploited to combat or delay ETR in ER positive breast cancers.
Project description:GNPS SILAC experiments of fives species with different mixtures of labelled amino acids. Data acquired on Q-Exactive with lockmass mz 622 / 922. In positive ion mode.
Project description:Streptomyces chartreusis feeding experiments with all proteinogenic amino acids in minimal medium. Analysis of the calcimycin and analogs production in the culture supernatant by LC-MS/MS.
RAW Files were used to generate Figures 1 and 2.
Project description:Dietary amino acids restriction extends lifespan in diverse species ranging from flies to mammals. The evolutionarily conserved serine/threonine kinase General Control Nonderepressible 2 (GCN2) is a key sensor of amino acid deficiency and has been implicated in lifespan regulation upon dietary restriction. However, the role of individual essential amino acids (EAA) in modulating organismal lifespan and the underlying molecular mechanisms through which EAA mediate these effects are only partially understood. We generated a novel Drosophila GCN2 null mutant and systematically analyzed its response to individual amino acid deficiency.
Project description:Variation in translation-elongation kinetics along a transcript’s coding sequence plays an important role in the maintenance of cellular protein homeostasis by regulating co-translational protein folding, localization, and maturation. Translation-elongation speed is influenced by molecular factors within mRNA and protein sequences. For example, when proline is present in the ribosome’s P- or A-site translation slows down, but the effect of other pairs of amino acids, in the context of all 400 possible pairs, has not been characterized. Here, we study Saccharomyces cerevisiae using a combination of mutational experiments, bioinformatics, and evolutionary analyses, and show that many different pairs of amino acids and their associated tRNA molecules predictably and causally encode translation rate information when these pairs are present in the A- and P-sites of the ribosome independent of other factors known to influence translation speed, including mRNA structure, wobble base pairing, tripeptide motifs, positively charged upstream nascent chain residues, and cognate tRNA concentration. The fast-translating pairs of amino acids that we identify are enriched seven-fold relative to the slow-translating pairs across Saccharomyces cerevisiae’s proteome, while the slow-translating pairs are enriched downstream of domain boundaries. Thus, the chemical identity of amino acid pairs contributes to variability in translation rates, elongation kinetics are causally encoded in the primary structure of proteins, and signatures of evolutionary selection indicate their potential role in co-translational processes.