RESUMO
Brown adipose tissue (BAT) is best known for thermogenesis. Rodent studies demonstrated that enhanced BAT thermogenesis is tightly associated with increased energy expenditure, reduced body weight, and improved glucose homeostasis. However, human BAT is protective against type 2 diabetes, independent of body weight. The mechanism underlying this dissociation remains unclear. Here, we report that impaired mitochondrial catabolism of branched-chain amino acids (BCAAs) in BAT, by deleting mitochondrial BCAA carriers (MBCs), caused systemic insulin resistance without affecting energy expenditure and body weight. Brown adipocytes catabolized BCAA in the mitochondria as nitrogen donors for the biosynthesis of non-essential amino acids and glutathione. Impaired mitochondrial BCAA-nitrogen flux in BAT resulted in increased oxidative stress, decreased hepatic insulin signaling, and decreased circulating BCAA-derived metabolites. A high-fat diet attenuated BCAA-nitrogen flux and metabolite synthesis in BAT, whereas cold-activated BAT enhanced the synthesis. This work uncovers a metabolite-mediated pathway through which BAT controls metabolic health beyond thermogenesis.
Assuntos
Tecido Adiposo Marrom , Aminoácidos de Cadeia Ramificada , Resistência à Insulina , Mitocôndrias , Nitrogênio , Termogênese , Tecido Adiposo Marrom/metabolismo , Animais , Aminoácidos de Cadeia Ramificada/metabolismo , Camundongos , Nitrogênio/metabolismo , Mitocôndrias/metabolismo , Masculino , Humanos , Metabolismo Energético , Camundongos Endogâmicos C57BL , Estresse Oxidativo , Insulina/metabolismo , Dieta Hiperlipídica , Adipócitos Marrons/metabolismo , Transdução de SinaisRESUMO
Determining protein levels in each tissue and how they compare with RNA levels is important for understanding human biology and disease as well as regulatory processes that control protein levels. We quantified the relative protein levels from over 12,000 genes across 32 normal human tissues. Tissue-specific or tissue-enriched proteins were identified and compared to transcriptome data. Many ubiquitous transcripts are found to encode tissue-specific proteins. Discordance of RNA and protein enrichment revealed potential sites of synthesis and action of secreted proteins. The tissue-specific distribution of proteins also provides an in-depth view of complex biological events that require the interplay of multiple tissues. Most importantly, our study demonstrated that protein tissue-enrichment information can explain phenotypes of genetic diseases, which cannot be obtained by transcript information alone. Overall, our results demonstrate how understanding protein levels can provide insights into regulation, secretome, metabolism, and human diseases.
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Proteoma/genética , Proteômica/métodos , Transcriptoma/genética , Expressão Gênica/genética , Perfilação da Expressão Gênica/métodos , Humanos , Proteoma/fisiologia , RNA/genética , RNA Mensageiro/metabolismo , Transcriptoma/fisiologiaRESUMO
Protein synthesis is metabolically costly and must be tightly coordinated with changing cellular needs and nutrient availability. The cap-binding protein eIF4E makes the earliest contact between mRNAs and the translation machinery, offering a key regulatory nexus. We acutely depleted this essential protein and found surprisingly modest effects on cell growth and recovery of protein synthesis. Paradoxically, impaired protein biosynthesis upregulated genes involved in the catabolism of aromatic amino acids simultaneously with the induction of the amino acid biosynthetic regulon driven by the integrated stress response factor GCN4. We further identified the translational control of Pho85 cyclin 5 (PCL5), a negative regulator of Gcn4, that provides a consistent protein-to-mRNA ratio under varied translation environments. This regulation depended in part on a uniquely long poly(A) tract in the PCL5 5' UTR and poly(A) binding protein. Collectively, these results highlight how eIF4E connects protein synthesis to metabolic gene regulation, uncovering mechanisms controlling translation during environmental challenges.
Assuntos
Aminoácidos , Fator de Iniciação 4E em Eucariotos , Regulação Fúngica da Expressão Gênica , Biossíntese de Proteínas , Proteínas de Saccharomyces cerevisiae , Saccharomyces cerevisiae , Fator de Iniciação 4E em Eucariotos/metabolismo , Fator de Iniciação 4E em Eucariotos/genética , Proteínas de Saccharomyces cerevisiae/genética , Proteínas de Saccharomyces cerevisiae/metabolismo , Aminoácidos/metabolismo , Saccharomyces cerevisiae/genética , Saccharomyces cerevisiae/metabolismo , RNA Mensageiro/metabolismo , RNA Mensageiro/genética , Regiões 5' não Traduzidas , Fatores de Transcrição de Zíper de Leucina Básica/metabolismo , Fatores de Transcrição de Zíper de Leucina Básica/genética , Ciclinas/genética , Ciclinas/metabolismo , Proteínas de Ligação a Poli(A)/metabolismo , Proteínas de Ligação a Poli(A)/genéticaRESUMO
Activated macrophages adapt their metabolic pathways to drive the pro-inflammatory phenotype, but little is known about the biochemical underpinnings of this process. Here, we find that lipopolysaccharide (LPS) activates the pentose phosphate pathway, the serine synthesis pathway, and one-carbon metabolism, the synergism of which drives epigenetic reprogramming for interleukin-1ß (IL-1ß) expression. Glucose-derived ribose and one-carbon units fed by both glucose and serine metabolism are synergistically integrated into the methionine cycle through de novo ATP synthesis and fuel the generation of S-adenosylmethionine (SAM) during LPS-induced inflammation. Impairment of these metabolic pathways that feed SAM generation lead to anti-inflammatory outcomes, implicating SAM as an essential metabolite for inflammatory macrophages. Mechanistically, SAM generation maintains a relatively high SAM:S-adenosylhomocysteine ratio to support histone H3 lysine 36 trimethylation for IL-1ß production. We therefore identify a synergistic effect of glucose and amino acid metabolism on orchestrating SAM availability that is intimately linked to the chromatin state for inflammation.
Assuntos
Histonas/metabolismo , Macrófagos Peritoneais/metabolismo , S-Adenosilmetionina/metabolismo , Trifosfato de Adenosina/metabolismo , Adulto , Animais , Feminino , Humanos , Inflamação/induzido quimicamente , Inflamação/metabolismo , Inflamação/patologia , Interleucina-1beta/metabolismo , Lipopolissacarídeos/toxicidade , Macrófagos Peritoneais/patologia , Masculino , Metilação/efeitos dos fármacos , CamundongosRESUMO
Tissue homeostasis requires lineage fidelity of stem cells. Dysregulation of cell fate specification and differentiation leads to various diseases, yet the cellular and molecular mechanisms governing these processes remain elusive. We demonstrate that YAP/TAZ activation reprograms airway secretory cells, which subsequently lose their cellular identity and acquire squamous alveolar type 1 (AT1) fate in the lung. This cell fate conversion is mediated via distinctive transitional cell states of damage-associated transient progenitors (DATPs), recently shown to emerge during injury repair in mouse and human lungs. We further describe a YAP/TAZ signaling cascade to be integral for the fate conversion of secretory cells into AT1 fate, by modulating mTORC1/ATF4-mediated amino acid metabolism in vivo. Importantly, we observed aberrant activation of the YAP/TAZ-mTORC1-ATF4 axis in the altered airway epithelium of bronchiolitis obliterans syndrome, including substantial emergence of DATPs and AT1 cells with severe pulmonary fibrosis. Genetic and pharmacologic inhibition of mTORC1 activity suppresses lineage alteration and subepithelial fibrosis driven by YAP/TAZ activation, proposing a potential therapeutic target for human fibrotic lung diseases.
Assuntos
Proteínas Adaptadoras de Transdução de Sinal , Proteínas de Sinalização YAP , Proteínas Adaptadoras de Transdução de Sinal/genética , Proteínas Adaptadoras de Transdução de Sinal/metabolismo , Aminoácidos Essenciais , Animais , Diferenciação Celular , Alvo Mecanístico do Complexo 1 de Rapamicina/genética , Alvo Mecanístico do Complexo 1 de Rapamicina/metabolismo , CamundongosRESUMO
Arginase 1 (Arg1) and indoleamine 2,3-dioxygenase 1 (IDO1) are immunoregulatory enzymes catalyzing the degradation of l-arginine and l-tryptophan, respectively, resulting in local amino acid deprivation. In addition, unlike Arg1, IDO1 is also endowed with non-enzymatic signaling activity in dendritic cells (DCs). Despite considerable knowledge of their individual biology, no integrated functions of Arg1 and IDO1 have been reported yet. We found that IDO1 phosphorylation and consequent activation of IDO1 signaling in DCs was strictly dependent on prior expression of Arg1 and Arg1-dependent production of polyamines. Polyamines, either produced by DCs or released by bystander Arg1+ myeloid-derived suppressor cells, conditioned DCs toward an IDO1-dependent, immunosuppressive phenotype via activation of the Src kinase, which has IDO1-phosphorylating activity. Thus our data indicate that Arg1 and IDO1 are linked by an entwined pathway in immunometabolism and that their joint modulation could represent an important target for effective immunotherapy in several disease settings.
Assuntos
Arginase/imunologia , Células Dendríticas/imunologia , Tolerância Imunológica/fisiologia , Indolamina-Pirrol 2,3,-Dioxigenase/imunologia , Transdução de Sinais/imunologia , Animais , Arginase/metabolismo , Arginina/imunologia , Arginina/metabolismo , Western Blotting , Células Dendríticas/metabolismo , Feminino , Perfilação da Expressão Gênica , Indolamina-Pirrol 2,3,-Dioxigenase/metabolismo , Camundongos , Camundongos Endogâmicos C57BL , Reação em Cadeia da Polimerase em Tempo Real , Transcriptoma , Triptofano/imunologia , Triptofano/metabolismoRESUMO
Organisms across the tree of life colonize novel environments by partnering with bacterial symbionts. These symbioses are characterized by intimate integration of host/endosymbiont biology at multiple levels, including metabolically. Metabolic integration is particularly important for sap-feeding insects and their symbionts, which supplement nutritionally unbalanced host diets. Many studies reveal parallel evolution of host/endosymbiont metabolic complementarity in amino acid biosynthesis, raising questions about how amino acid metabolism is regulated, how regulatory mechanisms evolve, and the extent to which similar mechanisms evolve in different systems. In the aphid/Buchnera symbiosis, the transporter ApGLNT1 (Acyrthosiphon pisum glutamine transporter 1) supplies glutamine, an amino donor in transamination reactions, to bacteriocytes (where Buchnera reside) and is competitively inhibited by Buchnera-supplied arginine-consistent with a role regulating amino acid metabolism given host demand for Buchnera-produced amino acids. We examined how ApGLNT1 evolved a regulatory role by functionally characterizing orthologs in insects with and without endosymbionts. ApGLNT1 orthologs are functionally similar, and orthology searches coupled with homology modeling revealed that GLNT1 is ancient and structurally conserved across insects. Our results indicate that the ApGLNT1 symbiotic regulatory role is derived from its ancestral role and, in aphids, is likely facilitated by loss of arginine biosynthesis through the urea cycle. Given consistent loss of host arginine biosynthesis and retention of endosymbiont arginine supply, we hypothesize that GLNT1 is a general mechanism regulating amino acid metabolism in sap-feeding insects. This work fills a gap, highlighting the broad importance of co-option of ancestral proteins to novel contexts in the evolution of host/symbiont systems.
Assuntos
Afídeos , Buchnera , Animais , Glutamina/metabolismo , Afídeos/microbiologia , Buchnera/genética , Buchnera/metabolismo , Aminoácidos/metabolismo , Proteínas de Membrana Transportadoras/metabolismo , Arginina/metabolismo , Simbiose/fisiologiaRESUMO
Epithelial-to-mesenchymal transition (EMT) that endows cancer cells with increased invasive and migratory capacity enables cancer dissemination and metastasis. This process is tightly associated with metabolic reprogramming acquired for rewiring cell status and signaling pathways for survival in dietary insufficiency conditions. However, it remains largely unclear how transcription factor (TF)-mediated transcriptional programs are modulated during the EMT process. Here, we reveal that depletion of a key epithelial TF, ELF3 (E74-like factor-3), triggers a transforming growth factor ß (TGF-ß) signaling activation-like mesenchymal transcriptomic profile and metastatic features linked to the aminoacyl-tRNA biogenesis pathway. Moreover, the transcriptome alterations elicited by ELF3 depletion perfectly resemble an ATF4-dependent weak response to amino acid starvation. Intriguingly, we observe an exclusive enrichment of ELF3 and ATF4 in epithelial and TGF-ß-induced or ELF3-depletion-elicited mesenchymal enhancers, respectively, with rare co-binding on altered enhancers. We also find that the upregulation of aminoacyl-tRNA synthetases and some mesenchymal genes upon amino acid deprivation is diminished in ATF4-depleted cells. In sum, the loss of ELF3 binding on epithelial enhancers and the gain of ATF4 binding on the enhancers of mesenchymal factors and amino acid deprivation responsive genes facilitate the loss of epithelial cell features and the gain of TGF-ß-signaling-associated mesenchymal signatures, which further promote lung cancer cell metastasis.
Assuntos
Fator 4 Ativador da Transcrição , Aminoácidos , Proteínas de Ligação a DNA , Transição Epitelial-Mesenquimal , Regulação Neoplásica da Expressão Gênica , Fatores de Transcrição , Fator de Crescimento Transformador beta , Transição Epitelial-Mesenquimal/genética , Fator 4 Ativador da Transcrição/metabolismo , Fator 4 Ativador da Transcrição/genética , Humanos , Fatores de Transcrição/metabolismo , Fatores de Transcrição/genética , Aminoácidos/metabolismo , Fator de Crescimento Transformador beta/metabolismo , Proteínas de Ligação a DNA/metabolismo , Proteínas de Ligação a DNA/genética , Linhagem Celular Tumoral , Transdução de Sinais , Proteínas Proto-Oncogênicas c-ets/metabolismo , Proteínas Proto-Oncogênicas c-ets/genética , Transcriptoma , AnimaisRESUMO
Sugarcane molasses is one of the main raw materials for bioethanol production, and Saccharomyces cerevisiae is the major biofuel-producing organism. In this study, a batch fermentation model has been used to examine ethanol titers of deletion mutants for all yeast nonessential genes in this yeast genome. A total of 42 genes are identified to be involved in ethanol production during fermentation of sugarcane molasses. Deletion mutants of seventeen genes show increased ethanol titers, while deletion mutants for twenty-five genes exhibit reduced ethanol titers. Two MAP kinases Hog1 and Kss1 controlling the high osmolarity and glycerol (HOG) signaling and the filamentous growth, respectively, are negatively involved in the regulation of ethanol production. In addition, twelve genes involved in amino acid metabolism are crucial for ethanol production during fermentation. Our findings provide novel targets and strategies for genetically engineering industrial yeast strains to improve ethanol titer during fermentation of sugarcane molasses.
Assuntos
Saccharomycetales , Saccharum , Fermentação , Etanol/metabolismo , Saccharomyces cerevisiae/genética , Saccharomyces cerevisiae/metabolismo , Saccharum/genética , Saccharum/metabolismo , Saccharomycetales/metabolismo , Sistema de Sinalização das MAP Quinases , Melaço , AminoácidosRESUMO
BACKGROUND: A substantial proportion of sensitized individuals tolerate suspected foods without developing allergic symptoms; this phenomenon is known as sensitized tolerance. The immunogenic and metabolic features underlying the sensitized-tolerant phenotype remain largely unknown. OBJECTIVE: We aimed to uncover the metabolic signatures associated with clinical milk allergy (MA) and sensitized tolerance using metabolomics. METHODS: We characterized the serum metabolic and immunologic profiles of children with clinical IgE-mediated MA (n = 30) or milk-sensitized tolerance (n = 20) and healthy controls (n = 21). A comparative analysis was performed to identify dysregulated pathways associated with the clinical manifestations of food allergy. We also analyzed specific biomarkers indicative of different sensitization phenotypes in children with MA. The candidate metabolites were validated in an independent quantification cohort (n = 41). RESULTS: Metabolomic profiling confirmed the presence of a distinct metabolic signature that discriminated children with MA from those with milk-sensitized tolerance. Amino acid metabolites generated via arginine, proline, and glutathione metabolism were uniquely altered in children with sensitized tolerance. Arginine depletion and metabolism through the polyamine pathway to fuel glutamate synthesis were closely associated with suppression of clinical symptoms in the presence of allergen-specific IgE. In children with MA, the polysensitized state was characterized by disturbances in tryptophan metabolism. CONCLUSIONS: By combining untargeted metabolomics with targeted validation in an independent quantification cohort, we identified candidate metabolites as phenotypic and diagnostic biomarkers of food allergy. Our results provide insights into the pathologic mechanisms underlying childhood allergy and suggest potential therapeutic targets.
Assuntos
Aminoácidos , Biomarcadores , Tolerância Imunológica , Metabolômica , Hipersensibilidade a Leite , Humanos , Hipersensibilidade a Leite/imunologia , Hipersensibilidade a Leite/sangue , Masculino , Feminino , Aminoácidos/metabolismo , Criança , Pré-Escolar , Imunoglobulina E/sangue , Imunoglobulina E/imunologia , Fenótipo , Lactente , Animais , Alérgenos/imunologiaRESUMO
Ferredoxins are a family of iron-sulfur (Fe-S) cluster proteins that serve as essential electron donors in numerous cellular processes that are conserved through evolution. The promiscuous nature of ferredoxins as electron donors enables them to participate in many metabolic processes including steroid, heme, vitamin D, and Fe-S cluster biosynthesis in different organisms. However, the unique natural function(s) of each of the two human ferredoxins (FDX1 and FDX2) are still poorly characterized. We recently reported that FDX1 is both a crucial regulator of copper ionophore-induced cell death and serves as an upstream regulator of cellular protein lipoylation, a mitochondrial lipid-based post-translational modification naturally occurring on four mitochondrial enzymes that are crucial for TCA cycle function. Here we show that FDX1 directly regulates protein lipoylation by binding the lipoyl synthase (LIAS) enzyme promoting its functional binding to the lipoyl carrier protein GCSH and not through indirect regulation of cellular Fe-S cluster biosynthesis. Metabolite profiling revealed that the predominant cellular metabolic outcome of FDX1 loss of function is manifested through the regulation of the four lipoylation-dependent enzymes ultimately resulting in loss of cellular respiration and sensitivity to mild glucose starvation. Transcriptional profiling established that FDX1 loss-of-function results in the induction of both compensatory metabolism-related genes and the integrated stress response, consistent with our findings that FDX1 loss-of-function is conditionally lethal. Together, our findings establish that FDX1 directly engages with LIAS, promoting its role in cellular protein lipoylation, a process essential in maintaining cell viability under low glucose conditions.
Assuntos
Ferredoxinas , Lipoilação , Sulfurtransferases , Humanos , Ferredoxinas/genética , Ferredoxinas/metabolismo , Lipoilação/genética , Ligação Proteica , Respiração Celular/genética , Proliferação de Células/genética , Metaboloma , Sulfurtransferases/metabolismoRESUMO
Amino acids are essential building blocks for proteins, crucial energy sources for cell survival, and key signaling molecules supporting the resistant growth of tumor cells. In tumor cells, amino acid metabolic reprogramming is characterized by the enhanced uptake of amino acids as well as their aberrant synthesis, breakdown, and transport, leading to immune evasion and malignant progression of tumor cells. This article reviews the altered amino acid metabolism in tumor cells and its impact on tumor microenvironment, and also provides an overview of the current clinical applications of amino acid metabolism. Innovative drugs targeting amino acid metabolism hold great promise for precision and personalized cancer therapy.
RESUMO
Current kidney perfusion protocols are not optimized for addressing the ex vivo physiological and metabolic needs of the kidney. Ex vivo normothermic perfusion may be utilized to distinguish high-risk kidneys to determine suitability for transplantation. Here, we assessed the association of tissue metabolic changes with changes in a kidney injury biomarker and functional parameters in eight deceased donor kidneys deemed unsuitable for transplantation during a 12-hour ex vivo normothermic perfusion. The kidneys were grouped into good and poor performers based on blood flow and urine output. The mean age of the deceased kidney donors was 43 years with an average cold ischemia time of 37 hours. Urine output and creatinine clearance progressively increased and peaked at six hours post-perfusion among good performers. Poor performers had 71 ng/ml greater (95% confidence interval 1.5, 140) urinary neutrophil gelatinase-associated lipocalin at six hours compared to good performers corresponding to peak functional differences. Organ performance was distinguished by tissue metabolic differences in branched chain amino acid metabolism and that their tissue levels negatively correlated with urine output among all kidneys at six hours. Tissue lipid profiling showed poor performers were highlighted by the accumulation of membrane structure components including glycerolipids and sphingolipids at early perfusion time points. Thus, we showed that six hours is needed for kidney function recovery during ex vivo normothermic perfusion and that branched chain amino acid metabolism may be a major determinant of organ function and resilience.
RESUMO
Rhizobium leguminosarum aspartate aminotransferase (AatA) mutants show drastically reduced symbiotic nitrogen fixation in legume nodules. Whilst AatA reversibly transaminates the two major amino-donor compounds aspartate and glutamate, the reason for the lack of N2 fixation in the mutant has remained unclear. During our investigations into the role of AatA, we found that it catalyses an additional transamination reaction between aspartate and pyruvate, forming alanine. This secondary reaction runs at around 60â% of the canonical aspartate transaminase reaction rate and connects alanine biosynthesis to glutamate via aspartate. This may explain the lack of any glutamate-pyruvate transaminase activity in R. leguminosarum, which is common in eukaryotic and many prokaryotic genomes. However, the aspartate-to-pyruvate transaminase reaction is not needed for N2 fixation in legume nodules. Consequently, we show that aspartate degradation is required for N2 fixation, rather than biosynthetic transamination to form an amino acid. Hence, the enzyme aspartase, which catalyses the breakdown of aspartate to fumarate and ammonia, suppressed an AatA mutant and restored N2 fixation in pea nodules.
Assuntos
Aspartato Aminotransferases , Ácido Aspártico , Fixação de Nitrogênio , Pisum sativum , Rhizobium leguminosarum , Nódulos Radiculares de Plantas , Rhizobium leguminosarum/genética , Rhizobium leguminosarum/metabolismo , Rhizobium leguminosarum/enzimologia , Ácido Aspártico/metabolismo , Pisum sativum/microbiologia , Nódulos Radiculares de Plantas/microbiologia , Aspartato Aminotransferases/metabolismo , Aspartato Aminotransferases/genética , Especificidade por Substrato , Proteínas de Bactérias/metabolismo , Proteínas de Bactérias/genética , Simbiose , MutaçãoRESUMO
When cultured together under standard laboratory conditions Pseudomonas aeruginosa has been shown to be an effective inhibitor of Staphylococcus aureus. However, P. aeruginosa and S. aureus are commonly observed in coinfections of individuals with cystic fibrosis (CF) and in chronic wounds. Previous work from our group revealed that S. aureus isolates from CF infections are able to persist in the presence of P. aeruginosa strain PAO1 with a range of tolerances with some isolates being eliminated entirely and others maintaining large populations. In this study, we designed a serial transfer, evolution experiment to identify mutations that allow S. aureus to survive in the presence of P. aeruginosa. Using S. aureus USA300 JE2 as our ancestral strain, populations of S. aureus were repeatedly cocultured with fresh P. aeruginosa PAO1. After eight coculture periods, S. aureus populations that survived better in the presence of PAO1 were observed. We found two independent mutations in the highly conserved S. aureus aspartate transporter, gltT, that were unique to evolved P. aeruginosa-tolerant isolates. Subsequent phenotypic testing demonstrated that gltT mutants have reduced uptake of glutamate and outcompeted wild-type S. aureus when glutamate was absent from chemically defined media. These findings together demonstrate that the presence of P. aeruginosa exerts selective pressure on S. aureus to alter its uptake and metabolism of key amino acids when the two are cultured together.
Assuntos
Sistemas de Transporte de Aminoácidos , Fibrose Cística , Infecções por Pseudomonas , Infecções Estafilocócicas , Staphylococcus aureus , Sistemas de Transporte de Aminoácidos/genética , Biofilmes , Fibrose Cística/complicações , Glutamatos/genética , Glutamatos/metabolismo , Glutamatos/farmacologia , Mutação , Pseudomonas aeruginosa/metabolismo , Staphylococcus aureus/genética , Proteínas de Bactérias/genéticaRESUMO
Malignant tumors are characterized by a hypoxic microenvironment, and metabolic reprogramming is necessary to ensure energy production and oxidative stress resistance. Although the microenvironmental properties of tumors vary under acute and chronic hypoxia, studies on chronic hypoxia-induced metabolic changes are limited. In the present study, we performed a comprehensive metabolic analysis in a chronic hypoxia model using colorectal cancer (CRC) organoids, and identified an amino acid supply system through the γ-glutamyl cycle, a glutathione recycling pathway. We analyzed the metabolic changes caused by hypoxia over time and observed that chronic hypoxia resulted in an increase in 5-oxoproline and a decrease in oxidized glutathione (GSSG) compared to acute hypoxia. These findings suggest that chronic hypoxia induces metabolic changes in the γ-glutamyl cycle. Moreover, inhibition of the γ-glutamyl cycle via γ-glutamyl cyclotransferase (GGCT) and γ-glutamyl transferase 1 (GGT1) knockdown significantly reversed chronic hypoxia-induced upregulation of 5-oxoproline and several amino acids. Notably, GGT1 knockdown downregulated the intracellular levels of γ-glutamyl amino acids. Conclusively, these results indicate that the γ-glutamyl cycle serves as an amino acid supply system in CRC under chronic hypoxia, which provides fresh insight into cancer metabolism under chronic hypoxia.
Assuntos
Aminoácidos , Neoplasias Colorretais , Organoides , gama-Glutamiltransferase , Neoplasias Colorretais/metabolismo , Neoplasias Colorretais/patologia , Humanos , Organoides/metabolismo , Organoides/patologia , gama-Glutamiltransferase/metabolismo , Aminoácidos/metabolismo , Hipóxia Celular , Microambiente Tumoral , Glutationa/metabolismo , Hipóxia/metabolismo , Hipóxia Tumoral , gama-Glutamilciclotransferase/metabolismo , gama-Glutamilciclotransferase/genéticaRESUMO
BACKGROUND: A better understanding of lung cancer etiology and the development of screening biomarkers have important implications for lung cancer prevention. METHODS: We included 623 matched case-control pairs from the Cancer Prevention Study (CPS) cohorts. Pre-diagnosis blood samples were collected between 1998 and 2001 in the CPS-II Nutrition cohort and 2006 and 2013 in the CPS-3 cohort and were sent for metabolomics profiling simultaneously. Cancer-free controls at the time of case diagnosis were 1:1 matched to cases on date of birth, blood draw date, sex, and race/ethnicity. Odds ratios (ORs) and 95% confidence intervals (CIs) were estimated using conditional logistic regression, controlling for confounders. The Benjamini-Hochberg method was used to correct for multiple comparisons. RESULTS: Sphingomyelin (d18:0/22:0) (OR: 1.32; 95% CI: 1.15, 1.53, FDR = 0.15) and taurodeoxycholic acid 3-sulfate (OR: 1.33; 95% CI: 1.14, 1.55, FDR = 0.15) were positively associated with lung cancer risk. Participants diagnosed within 3 years of blood draw had a 55% and 48% higher risk of lung cancer per standard deviation increase in natural log-transformed sphingomyelin (d18:0/22:0) and taurodeoxycholic acid 3-sulfate level, while 26% and 28% higher risk for those diagnosed beyond 3 years, compared to matched controls. Lipid and amino acid metabolism accounted for 47% to 80% of lung cancer-associated metabolites at P < 0.05 across all participants and subgroups. Notably, ever-smokers exhibited a higher proportion of lung cancer-associated metabolites (P < 0.05) in xenobiotic- and lipid-associated pathways, whereas never-smokers showed a more pronounced involvement of amino acid- and lipid-associated metabolic pathways. CONCLUSIONS: This is the largest prospective study examining untargeted metabolic profiles regarding lung cancer risk. Sphingomyelin (d18:0/22:0), a sphingolipid, and taurodeoxycholic acid 3-sulfate, a bile salt, may be risk factors and potential screening biomarkers for lung cancer. Lipid and amino acid metabolism may contribute significantly to lung cancer etiology which varied by smoking status.
Assuntos
Neoplasias Pulmonares , Metabolômica , Humanos , Neoplasias Pulmonares/sangue , Neoplasias Pulmonares/prevenção & controle , Neoplasias Pulmonares/epidemiologia , Neoplasias Pulmonares/diagnóstico , Masculino , Feminino , Metabolômica/métodos , Estudos de Casos e Controles , Pessoa de Meia-Idade , Idoso , Esfingomielinas/sangueRESUMO
PURPOSE OF THE STUDY: Breast density is an established risk factor for breast cancer. However, little is known about metabolic influences on breast density phenotypes. We conducted untargeted serum metabolomics analyses to identify metabolic signatures associated with breast density phenotypes among young women. METHODS: In a cross-sectional study of 173 young women aged 25-29 who participated in the Dietary Intervention Study in Children 2006 Follow-up Study, 449 metabolites were measured in fasting serum samples using ultra-high-performance liquid chromatography-tandem mass spectrometry. Multivariable-adjusted mixed-effects linear regression identified metabolites associated with magnetic resonance imaging measured breast density phenotypes: percent dense breast volume (%DBV), absolute dense breast volume (ADBV), and absolute non-dense breast volume (ANDBV). Metabolite results were corrected for multiple comparisons using a false discovery rate adjusted p-value (q). RESULTS: The amino acids valine and leucine were significantly inversely associated with %DBV. For each 1 SD increase in valine and leucine, %DBV decreased by 20.9% (q = 0.02) and 18.4% (q = 0.04), respectively. ANDBV was significantly positively associated with 16 lipid and one amino acid metabolites, whereas no metabolites were associated with ADBV. Metabolite set enrichment analysis also revealed associations of distinct metabolic signatures with %DBV, ADBV, and ANDBV; branched chain amino acids had the strongest inverse association with %DBV (p = 0.002); whereas, diacylglycerols and phospholipids were positively associated with ANDBV (p ≤ 0.002), no significant associations were observed for ADBV. CONCLUSION: Our results suggest an inverse association of branched chain amino acids with %DBV. Larger studies in diverse populations are needed.
Assuntos
Densidade da Mama , Neoplasias da Mama , Criança , Feminino , Humanos , Leucina , Estudos Transversais , Seguimentos , Mamografia , Aminoácidos de Cadeia Ramificada , ValinaRESUMO
OBJECTIVES: Inherited amino-acid metabolism disorders (IAAMDs) require lifelong protein-restricted diet. We aimed to investigate: 1/ whether IAAMDs was associated with growth, pubertal, bone mineral apparent density (BMAD) or body composition impairments; 2/ associations linking height, amino-acid mixture (AAM), plasma amino-acids and IGF1 concentrations. DESIGN: Retrospective longitudinal study of 213 patients with neonatal-onset urea cycle disorders (UCD,n = 77), organic aciduria (OA,n = 89), maple syrup urine disease (MSUD,n = 34), or tyrosinaemia type 1 (n = 13). METHODS: We collected growth parameters, pubertal status, BMAD, body composition, protein-intake, and IGF1 throughout growth. RESULTS: Overall final height (n = 69) was below target height (TH): -0.9(1.4) vs. -0.1(0.9) SD, p < 0.001. Final height was ≤ TH-2SD in 12 (21%) patients. Height ≤ - 2SD was more frequent during puberty than during early-infancy and pre-puberty: 23.5% vs. 6.9%, p = 0.002; and vs. 10.7%, p < 0.001. Pubertal delay was frequent (26.7%). Height (SD) was positively associated with isoleucine concentration: ß, 0.008; 95%CI, 0.003 to 0.012; p = 0.001. In the pubertal subgroup, height (SD) was lower in patients with vs. without AAM supplementation: -1.22 (1.40) vs. -0.63 (1.46) (p = 0.02). In OA, height and median (IQR) isoleucine and valine concentrations(µmol/L) during puberty were lower in patients with vs. without AAM supplementation: -1.75 (1.30) vs. -0.33 (1.55) SD, p < 0.001; and 40 (23) vs. 60 (25) (p = 0.02) and 138 (92) vs. 191 (63) (p = 0.01), respectively. No correlation was found with IGF1. Lean-mass index was lower than fat-mass index: -2.03 (1.15) vs. -0.44 (0.89), p < 0.001. CONCLUSIONS: In IAAMDs, growth retardation worsened during puberty which was delayed in all disease subgroups. Height seems linked to the disease, AAM composition and lower isoleucine concentration, independently of the GH-IGF1 pathway. We recommend close monitoring of diet during puberty.
Assuntos
Erros Inatos do Metabolismo dos Aminoácidos , Doença da Urina de Xarope de Bordo , Recém-Nascido , Humanos , Estudos Longitudinais , Estudos Retrospectivos , Isoleucina , Transtornos do Crescimento , Erros Inatos do Metabolismo dos Aminoácidos/genética , Aminoácidos , EstaturaRESUMO
The first and committed step in proline synthesis from glutamate is catalyzed by δ1 -pyrroline-5-carboxylate synthetase (P5CS). Two P5CS genes have been found in most angiosperms, one constitutively expressed to satisfy proline demand for protein synthesis, the other stress-induced. Despite the number of papers to investigate regulation at the transcriptional level, to date, the properties of the enzymes have been subjected to limited study. The isolation of Arabidopsis thaliana P5CS isoenzymes was achieved through heterologous expression and affinity purification. The two proteins were characterized with respect to kinetic and biochemical properties. AtP5CS2 showed KM values in the micro- to millimolar range, and its activity was inhibited by NADP+ , ADP and proline, and by glutamine and arginine at high levels. Mg2+ ions were required for activity, which was further stimulated by K+ and other cations. AtP5CS1 displayed positive cooperativity with glutamate and was almost insensitive to inhibition by proline. In the presence of physiological, nonsaturating concentrations of glutamate, proline was slightly stimulatory, and glutamine strongly increased the catalytic rate. Data suggest that the activity of AtP5CS isoenzymes is differentially regulated by a complex array of factors including the concentrations of proline, glutamate, glutamine, monovalent cations and pyridine dinucleotides.