34 research outputs found
Quantification Annotation in ISO 24617-12, Second Draft
International audienceThis paper describes the continuation of a project that aims at establishing an interoperable annotation scheme for quantification phenomena as part of the ISO suite of standards for semantic annotation, known as the Semantic Annotation Framework. After a break, caused by the Covid-19 pandemic, the project was relaunched in early 2022 with a second working draft, which deals with certain issues in the annotation of quantification in a more satisfactory way than the original first working draft
Preâbreakup extension in the northern North Sea defined by complex strain partitioning and heterogeneous extension rates
The early stages of continental rifting are accommodated by the growth of upperâcrustal normal fault systems that are distributed relatively evenly across the rift width. Numerous fault systems define fault arrays , the kinematics of which are poorly understood due to a lack of regional studies drawing on highâquality subsurface data. Here we investigate the longâterm (~150 Myr) growth of a riftârelated fault array in the East Shetland Basin, northern North Sea, using a regionally extensive subsurface dataset comprising 2D and 3D seismic reflection surveys and 107 boreholes. We show that riftârelated strain during the preâTriassicâtoâMiddle Triassic was originally distributed across several subâbasins. The MiddleâtoâLate Triassic saw a decrease in extension rate (~14 m/Myr) as strain localized in the western part of the basin. Early Jurassic strain initially migrated eastwards, before becoming more diffuse during the main, MiddleâtoâLate Jurassic rift phase. The highest extension rates (~89 m/Myr) corresponded with the main rift event in the East Shetland Basin, before focusing of strain within the rift axis and ultimate abandonment of the East Shetland Basin in the Early Cretaceous. We also demonstrate marked spatial variations in timing and magnitude of slip alongâstrike of major fault systems during this protracted rift event. Our results imply that strain migration patterns and extension rates during the initial, preâbreakup phase of continental rifting may be more complex than previously thought; this reflects temporal and spatial changes in both thermal and mechanical properties of the lithosphere, in addition to varying extension rates
Modifications mĂ©taboliques et fonctionnelles des cellules ÎČ pancrĂ©atiques au cours du diabĂšte de type 2
Insulin is a hormone contributing to blood glucose homeostasis by promoting its absorption by targeted cells from insulin-sensitive tissues, in particular the liver, muscle, and adipose tissue. During type 2 diabetes (T2D), the capacity of insulin-sensitive tissues to respond to insulin decreases leading to the progressive development of chronic hyperglycemia. This creates a vicious cycle contributing to insulin-secreting ÎČ cells release more insulin to compensate for the lack of glycemic regulation until their exhaustion. Chronic hyperglycemia brings an excess of energetic substrate in form of circulating glucose, inducing a glucotoxicity but also into lipids, inducing a lipotoxicity. Altogether it results in ATP turnover defect which is crucial for ÎČ cell insulin synthesis and secretion. Intracellular metabolism homeostasis modifications are key markers of ÎČ cell metabolism reshaping occurring during T2D but the exchanges of metabolites between cells and their environment remain unknown. To characterize these exchanges, we have cultured for 48 h human pancreatic islets and INS-1E murine ÎČ cell line with different glucose and palmitate concentrations to mimic T2D-associated glucolipotoxicity. A metabolomic study through high-resolution proton nuclear magnetic resonance (1H-NMR) completed with biochemical analysis allowed us to reveal key energetic metabolism modifications. These modifications were associated with alterations of mitochondrial dehydrogenase expression and regulation perturbing the citric acid cycle (TCA). Human islets and INS-1E cells show a similar metabolomic signature led by glucolipotoxicity. However, citrate is directly secreted out of the cell in a human islets model while this metabolite may be used for lipid synthesis supporting a higher triglyceride secretion in the INS-1E model. These results are consistent with previous works done by our team showing modifications of mitochondria-endoplasmic reticulum contact sites associated with a decrease of mitochondrial respiration during chronic exposure to high glucose concentration. Thus, we propose a model where, as in T2D, ÎČ pancreatic cells exposition to high glucose and lipid concentrations lead to mitochondrial stress. This stress leads to a glycolysis-TCA cycle-insulin secretion axes modification where islets and ÎČ cells oversecrete pyruvate, citrate, or triglycerides, limiting ATP renewing required for insulin secretion.Lâinsuline est une hormone contribuant Ă lâhomĂ©ostasie du glucose dans le sang en favorisant son absorption par ces cellules cibles des tissus insulino-sensibles tels que le foie, le muscle et le tissu adipeux. Lors dâun diabĂšte de type 2 (DT2) les tissus insulino-sensibles voient diminuer leur capacitĂ© Ă rĂ©pondre Ă lâinsuline mettant progressivement en place une hyperglycĂ©mie chronique. Pour rĂ©pondre Ă la demande accrue en insuline dĂ©coulant de lâinsensibilitĂ© des tissus cibles, les cellules ÎČ pancrĂ©atiques insulino-sĂ©crĂ©trices libĂšrent davantage dâinsuline jusquâĂ sâĂ©puiser. LâexcĂšs de substrats Ă©nergĂ©tiques circulants sous forme de glucose, induisant une glucotoxicitĂ©, et de lipides, induisant une lipotoxicitĂ©, mĂšne Ă un dĂ©faut de renouvellement dâATP, qui est substrat crucial pour la synthĂšse et la sĂ©crĂ©tion rĂ©gulĂ©e dâinsuline par les cellules ÎČ pancrĂ©atiques. Les modifications de lâhomĂ©ostasie mĂ©tabolique intracellulaire sont des marqueurs du remodelage du mĂ©tabolisme des cellules ÎČ au cours du DT2 mais les Ă©changes entre ces cellules et leur environnement restent inconnus. En vue dâĂ©tudier la nature mĂ©tabolique de ces Ă©changes, nous avons soumis des Ăźlots pancrĂ©atiques humains et un modĂšle de cellules ÎČ murines INS-1E Ă diffĂ©rentes concentrations de glucose et de palmitate pendant 48h afin de mimer les consĂ©quences de la gluco-lipotoxicitĂ© associĂ©e au DT2. Une Ă©tude de mĂ©tabolomique par rĂ©sonance magnĂ©tique nuclĂ©aire du proton en complĂ©ment dâanalyses biochimiques nous ont permis de rĂ©vĂ©ler des modifications majeures du mĂ©tabolisme Ă©nergĂ©tique. Ces modifications sont associĂ©es Ă des altĂ©rations dâexpressions et de rĂ©gulations de dĂ©shydrogĂ©nases mitochondriales perturbant le cycle du citrate. La signature mĂ©tabolomique en condition de glucolipotoxicitĂ© est proche entre les Ăźlots humains et les INS-1E. Cependant, alors que le citrate est directement sĂ©crĂ©tĂ© hors de la cellule dans le modĂšle des Ăźlots humains, il apparait utilisĂ© au profit de la synthĂšse de lipides supportant une sĂ©crĂ©tion de triglycĂ©rides dans le modĂšle INS-1E. Ces rĂ©sultats sont en cohĂ©rence avec les travaux prĂ©cĂ©demment rĂ©alisĂ©s par notre Ă©quipe montrant que des modifications des contacts entre la mitochondrie et le rĂ©ticulum endoplasmique sont associĂ©es Ă une diminution de la respiration mitochondriale lors de conditions mimant la glucotoxicitĂ©. Ainsi nous proposons un modĂšle oĂč, comme lors du DT2, les cellules ÎČ pancrĂ©atiques sont soumises Ă de fortes quantitĂ©s de glucose et de lipides induisant un stress mitochondrial. Ce stress conduit Ă lâaltĂ©ration de lâaxe glycolyse-cycle du citrate-sĂ©crĂ©tion dâinsuline associĂ©e Ă une secrĂ©tions importante de pyruvate, de citrate ou de triglycĂ©rides, ne permettant plus le renouvellement dâATP nĂ©cessaire Ă la sĂ©crĂ©tion dâinsuline
ÎČ pancreatic cell metabolic and functional modifications during type 2 diabetes
Lâinsuline est une hormone contribuant Ă lâhomĂ©ostasie du glucose dans le sang en favorisant son absorption par ces cellules cibles des tissus insulino-sensibles tels que le foie, le muscle et le tissu adipeux. Lors dâun diabĂšte de type 2 (DT2) les tissus insulino-sensibles voient diminuer leur capacitĂ© Ă rĂ©pondre Ă lâinsuline mettant progressivement en place une hyperglycĂ©mie chronique. Pour rĂ©pondre Ă la demande accrue en insuline dĂ©coulant de lâinsensibilitĂ© des tissus cibles, les cellules ÎČ pancrĂ©atiques insulino-sĂ©crĂ©trices libĂšrent davantage dâinsuline jusquâĂ sâĂ©puiser. LâexcĂšs de substrats Ă©nergĂ©tiques circulants sous forme de glucose, induisant une glucotoxicitĂ©, et de lipides, induisant une lipotoxicitĂ©, mĂšne Ă un dĂ©faut de renouvellement dâATP, qui est substrat crucial pour la synthĂšse et la sĂ©crĂ©tion rĂ©gulĂ©e dâinsuline par les cellules ÎČ pancrĂ©atiques. Les modifications de lâhomĂ©ostasie mĂ©tabolique intracellulaire sont des marqueurs du remodelage du mĂ©tabolisme des cellules ÎČ au cours du DT2 mais les Ă©changes entre ces cellules et leur environnement restent inconnus. En vue dâĂ©tudier la nature mĂ©tabolique de ces Ă©changes, nous avons soumis des Ăźlots pancrĂ©atiques humains et un modĂšle de cellules ÎČ murines INS-1E Ă diffĂ©rentes concentrations de glucose et de palmitate pendant 48h afin de mimer les consĂ©quences de la gluco-lipotoxicitĂ© associĂ©e au DT2. Une Ă©tude de mĂ©tabolomique par rĂ©sonance magnĂ©tique nuclĂ©aire du proton en complĂ©ment dâanalyses biochimiques nous ont permis de rĂ©vĂ©ler des modifications majeures du mĂ©tabolisme Ă©nergĂ©tique. Ces modifications sont associĂ©es Ă des altĂ©rations dâexpressions et de rĂ©gulations de dĂ©shydrogĂ©nases mitochondriales perturbant le cycle du citrate. La signature mĂ©tabolomique en condition de glucolipotoxicitĂ© est proche entre les Ăźlots humains et les INS-1E. Cependant, alors que le citrate est directement sĂ©crĂ©tĂ© hors de la cellule dans le modĂšle des Ăźlots humains, il apparait utilisĂ© au profit de la synthĂšse de lipides supportant une sĂ©crĂ©tion de triglycĂ©rides dans le modĂšle INS-1E. Ces rĂ©sultats sont en cohĂ©rence avec les travaux prĂ©cĂ©demment rĂ©alisĂ©s par notre Ă©quipe montrant que des modifications des contacts entre la mitochondrie et le rĂ©ticulum endoplasmique sont associĂ©es Ă une diminution de la respiration mitochondriale lors de conditions mimant la glucotoxicitĂ©. Ainsi nous proposons un modĂšle oĂč, comme lors du DT2, les cellules ÎČ pancrĂ©atiques sont soumises Ă de fortes quantitĂ©s de glucose et de lipides induisant un stress mitochondrial. Ce stress conduit Ă lâaltĂ©ration de lâaxe glycolyse-cycle du citrate-sĂ©crĂ©tion dâinsuline associĂ©e Ă une secrĂ©tions importante de pyruvate, de citrate ou de triglycĂ©rides, ne permettant plus le renouvellement dâATP nĂ©cessaire Ă la sĂ©crĂ©tion dâinsuline.Insulin is a hormone contributing to blood glucose homeostasis by promoting its absorption by targeted cells from insulin-sensitive tissues, in particular the liver, muscle, and adipose tissue. During type 2 diabetes (T2D), the capacity of insulin-sensitive tissues to respond to insulin decreases leading to the progressive development of chronic hyperglycemia. This creates a vicious cycle contributing to insulin-secreting ÎČ cells release more insulin to compensate for the lack of glycemic regulation until their exhaustion. Chronic hyperglycemia brings an excess of energetic substrate in form of circulating glucose, inducing a glucotoxicity but also into lipids, inducing a lipotoxicity. Altogether it results in ATP turnover defect which is crucial for ÎČ cell insulin synthesis and secretion. Intracellular metabolism homeostasis modifications are key markers of ÎČ cell metabolism reshaping occurring during T2D but the exchanges of metabolites between cells and their environment remain unknown. To characterize these exchanges, we have cultured for 48 h human pancreatic islets and INS-1E murine ÎČ cell line with different glucose and palmitate concentrations to mimic T2D-associated glucolipotoxicity. A metabolomic study through high-resolution proton nuclear magnetic resonance (1H-NMR) completed with biochemical analysis allowed us to reveal key energetic metabolism modifications. These modifications were associated with alterations of mitochondrial dehydrogenase expression and regulation perturbing the citric acid cycle (TCA). Human islets and INS-1E cells show a similar metabolomic signature led by glucolipotoxicity. However, citrate is directly secreted out of the cell in a human islets model while this metabolite may be used for lipid synthesis supporting a higher triglyceride secretion in the INS-1E model. These results are consistent with previous works done by our team showing modifications of mitochondria-endoplasmic reticulum contact sites associated with a decrease of mitochondrial respiration during chronic exposure to high glucose concentration. Thus, we propose a model where, as in T2D, ÎČ pancreatic cells exposition to high glucose and lipid concentrations lead to mitochondrial stress. This stress leads to a glycolysis-TCA cycle-insulin secretion axes modification where islets and ÎČ cells oversecrete pyruvate, citrate, or triglycerides, limiting ATP renewing required for insulin secretion
Modifications mĂ©taboliques et fonctionnelles des cellules ÎČ pancrĂ©atiques au cours du diabĂšte de type 2
Insulin is a hormone contributing to blood glucose homeostasis by promoting its absorption by targeted cells from insulin-sensitive tissues, in particular the liver, muscle, and adipose tissue. During type 2 diabetes (T2D), the capacity of insulin-sensitive tissues to respond to insulin decreases leading to the progressive development of chronic hyperglycemia. This creates a vicious cycle contributing to insulin-secreting ÎČ cells release more insulin to compensate for the lack of glycemic regulation until their exhaustion. Chronic hyperglycemia brings an excess of energetic substrate in form of circulating glucose, inducing a glucotoxicity but also into lipids, inducing a lipotoxicity. Altogether it results in ATP turnover defect which is crucial for ÎČ cell insulin synthesis and secretion. Intracellular metabolism homeostasis modifications are key markers of ÎČ cell metabolism reshaping occurring during T2D but the exchanges of metabolites between cells and their environment remain unknown. To characterize these exchanges, we have cultured for 48 h human pancreatic islets and INS-1E murine ÎČ cell line with different glucose and palmitate concentrations to mimic T2D-associated glucolipotoxicity. A metabolomic study through high-resolution proton nuclear magnetic resonance (1H-NMR) completed with biochemical analysis allowed us to reveal key energetic metabolism modifications. These modifications were associated with alterations of mitochondrial dehydrogenase expression and regulation perturbing the citric acid cycle (TCA). Human islets and INS-1E cells show a similar metabolomic signature led by glucolipotoxicity. However, citrate is directly secreted out of the cell in a human islets model while this metabolite may be used for lipid synthesis supporting a higher triglyceride secretion in the INS-1E model. These results are consistent with previous works done by our team showing modifications of mitochondria-endoplasmic reticulum contact sites associated with a decrease of mitochondrial respiration during chronic exposure to high glucose concentration. Thus, we propose a model where, as in T2D, ÎČ pancreatic cells exposition to high glucose and lipid concentrations lead to mitochondrial stress. This stress leads to a glycolysis-TCA cycle-insulin secretion axes modification where islets and ÎČ cells oversecrete pyruvate, citrate, or triglycerides, limiting ATP renewing required for insulin secretion.Lâinsuline est une hormone contribuant Ă lâhomĂ©ostasie du glucose dans le sang en favorisant son absorption par ces cellules cibles des tissus insulino-sensibles tels que le foie, le muscle et le tissu adipeux. Lors dâun diabĂšte de type 2 (DT2) les tissus insulino-sensibles voient diminuer leur capacitĂ© Ă rĂ©pondre Ă lâinsuline mettant progressivement en place une hyperglycĂ©mie chronique. Pour rĂ©pondre Ă la demande accrue en insuline dĂ©coulant de lâinsensibilitĂ© des tissus cibles, les cellules ÎČ pancrĂ©atiques insulino-sĂ©crĂ©trices libĂšrent davantage dâinsuline jusquâĂ sâĂ©puiser. LâexcĂšs de substrats Ă©nergĂ©tiques circulants sous forme de glucose, induisant une glucotoxicitĂ©, et de lipides, induisant une lipotoxicitĂ©, mĂšne Ă un dĂ©faut de renouvellement dâATP, qui est substrat crucial pour la synthĂšse et la sĂ©crĂ©tion rĂ©gulĂ©e dâinsuline par les cellules ÎČ pancrĂ©atiques. Les modifications de lâhomĂ©ostasie mĂ©tabolique intracellulaire sont des marqueurs du remodelage du mĂ©tabolisme des cellules ÎČ au cours du DT2 mais les Ă©changes entre ces cellules et leur environnement restent inconnus. En vue dâĂ©tudier la nature mĂ©tabolique de ces Ă©changes, nous avons soumis des Ăźlots pancrĂ©atiques humains et un modĂšle de cellules ÎČ murines INS-1E Ă diffĂ©rentes concentrations de glucose et de palmitate pendant 48h afin de mimer les consĂ©quences de la gluco-lipotoxicitĂ© associĂ©e au DT2. Une Ă©tude de mĂ©tabolomique par rĂ©sonance magnĂ©tique nuclĂ©aire du proton en complĂ©ment dâanalyses biochimiques nous ont permis de rĂ©vĂ©ler des modifications majeures du mĂ©tabolisme Ă©nergĂ©tique. Ces modifications sont associĂ©es Ă des altĂ©rations dâexpressions et de rĂ©gulations de dĂ©shydrogĂ©nases mitochondriales perturbant le cycle du citrate. La signature mĂ©tabolomique en condition de glucolipotoxicitĂ© est proche entre les Ăźlots humains et les INS-1E. Cependant, alors que le citrate est directement sĂ©crĂ©tĂ© hors de la cellule dans le modĂšle des Ăźlots humains, il apparait utilisĂ© au profit de la synthĂšse de lipides supportant une sĂ©crĂ©tion de triglycĂ©rides dans le modĂšle INS-1E. Ces rĂ©sultats sont en cohĂ©rence avec les travaux prĂ©cĂ©demment rĂ©alisĂ©s par notre Ă©quipe montrant que des modifications des contacts entre la mitochondrie et le rĂ©ticulum endoplasmique sont associĂ©es Ă une diminution de la respiration mitochondriale lors de conditions mimant la glucotoxicitĂ©. Ainsi nous proposons un modĂšle oĂč, comme lors du DT2, les cellules ÎČ pancrĂ©atiques sont soumises Ă de fortes quantitĂ©s de glucose et de lipides induisant un stress mitochondrial. Ce stress conduit Ă lâaltĂ©ration de lâaxe glycolyse-cycle du citrate-sĂ©crĂ©tion dâinsuline associĂ©e Ă une secrĂ©tions importante de pyruvate, de citrate ou de triglycĂ©rides, ne permettant plus le renouvellement dâATP nĂ©cessaire Ă la sĂ©crĂ©tion dâinsuline
Modifications mĂ©taboliques et fonctionnelles des cellules ÎČ pancrĂ©atiques au cours du diabĂšte de type 2
Insulin is a hormone contributing to blood glucose homeostasis by promoting its absorption by targeted cells from insulin-sensitive tissues, in particular the liver, muscle, and adipose tissue. During type 2 diabetes (T2D), the capacity of insulin-sensitive tissues to respond to insulin decreases leading to the progressive development of chronic hyperglycemia. This creates a vicious cycle contributing to insulin-secreting ÎČ cells release more insulin to compensate for the lack of glycemic regulation until their exhaustion. Chronic hyperglycemia brings an excess of energetic substrate in form of circulating glucose, inducing a glucotoxicity but also into lipids, inducing a lipotoxicity. Altogether it results in ATP turnover defect which is crucial for ÎČ cell insulin synthesis and secretion. Intracellular metabolism homeostasis modifications are key markers of ÎČ cell metabolism reshaping occurring during T2D but the exchanges of metabolites between cells and their environment remain unknown. To characterize these exchanges, we have cultured for 48 h human pancreatic islets and INS-1E murine ÎČ cell line with different glucose and palmitate concentrations to mimic T2D-associated glucolipotoxicity. A metabolomic study through high-resolution proton nuclear magnetic resonance (1H-NMR) completed with biochemical analysis allowed us to reveal key energetic metabolism modifications. These modifications were associated with alterations of mitochondrial dehydrogenase expression and regulation perturbing the citric acid cycle (TCA). Human islets and INS-1E cells show a similar metabolomic signature led by glucolipotoxicity. However, citrate is directly secreted out of the cell in a human islets model while this metabolite may be used for lipid synthesis supporting a higher triglyceride secretion in the INS-1E model. These results are consistent with previous works done by our team showing modifications of mitochondria-endoplasmic reticulum contact sites associated with a decrease of mitochondrial respiration during chronic exposure to high glucose concentration. Thus, we propose a model where, as in T2D, ÎČ pancreatic cells exposition to high glucose and lipid concentrations lead to mitochondrial stress. This stress leads to a glycolysis-TCA cycle-insulin secretion axes modification where islets and ÎČ cells oversecrete pyruvate, citrate, or triglycerides, limiting ATP renewing required for insulin secretion.Lâinsuline est une hormone contribuant Ă lâhomĂ©ostasie du glucose dans le sang en favorisant son absorption par ces cellules cibles des tissus insulino-sensibles tels que le foie, le muscle et le tissu adipeux. Lors dâun diabĂšte de type 2 (DT2) les tissus insulino-sensibles voient diminuer leur capacitĂ© Ă rĂ©pondre Ă lâinsuline mettant progressivement en place une hyperglycĂ©mie chronique. Pour rĂ©pondre Ă la demande accrue en insuline dĂ©coulant de lâinsensibilitĂ© des tissus cibles, les cellules ÎČ pancrĂ©atiques insulino-sĂ©crĂ©trices libĂšrent davantage dâinsuline jusquâĂ sâĂ©puiser. LâexcĂšs de substrats Ă©nergĂ©tiques circulants sous forme de glucose, induisant une glucotoxicitĂ©, et de lipides, induisant une lipotoxicitĂ©, mĂšne Ă un dĂ©faut de renouvellement dâATP, qui est substrat crucial pour la synthĂšse et la sĂ©crĂ©tion rĂ©gulĂ©e dâinsuline par les cellules ÎČ pancrĂ©atiques. Les modifications de lâhomĂ©ostasie mĂ©tabolique intracellulaire sont des marqueurs du remodelage du mĂ©tabolisme des cellules ÎČ au cours du DT2 mais les Ă©changes entre ces cellules et leur environnement restent inconnus. En vue dâĂ©tudier la nature mĂ©tabolique de ces Ă©changes, nous avons soumis des Ăźlots pancrĂ©atiques humains et un modĂšle de cellules ÎČ murines INS-1E Ă diffĂ©rentes concentrations de glucose et de palmitate pendant 48h afin de mimer les consĂ©quences de la gluco-lipotoxicitĂ© associĂ©e au DT2. Une Ă©tude de mĂ©tabolomique par rĂ©sonance magnĂ©tique nuclĂ©aire du proton en complĂ©ment dâanalyses biochimiques nous ont permis de rĂ©vĂ©ler des modifications majeures du mĂ©tabolisme Ă©nergĂ©tique. Ces modifications sont associĂ©es Ă des altĂ©rations dâexpressions et de rĂ©gulations de dĂ©shydrogĂ©nases mitochondriales perturbant le cycle du citrate. La signature mĂ©tabolomique en condition de glucolipotoxicitĂ© est proche entre les Ăźlots humains et les INS-1E. Cependant, alors que le citrate est directement sĂ©crĂ©tĂ© hors de la cellule dans le modĂšle des Ăźlots humains, il apparait utilisĂ© au profit de la synthĂšse de lipides supportant une sĂ©crĂ©tion de triglycĂ©rides dans le modĂšle INS-1E. Ces rĂ©sultats sont en cohĂ©rence avec les travaux prĂ©cĂ©demment rĂ©alisĂ©s par notre Ă©quipe montrant que des modifications des contacts entre la mitochondrie et le rĂ©ticulum endoplasmique sont associĂ©es Ă une diminution de la respiration mitochondriale lors de conditions mimant la glucotoxicitĂ©. Ainsi nous proposons un modĂšle oĂč, comme lors du DT2, les cellules ÎČ pancrĂ©atiques sont soumises Ă de fortes quantitĂ©s de glucose et de lipides induisant un stress mitochondrial. Ce stress conduit Ă lâaltĂ©ration de lâaxe glycolyse-cycle du citrate-sĂ©crĂ©tion dâinsuline associĂ©e Ă une secrĂ©tions importante de pyruvate, de citrate ou de triglycĂ©rides, ne permettant plus le renouvellement dâATP nĂ©cessaire Ă la sĂ©crĂ©tion dâinsuline
Warburg-associated acidification represses lactic fermentation independently of lactate, contribution from real-time NMR on cell-free systems
International audienceLactate accumulation and acidification in tumours are a cancer hallmark associated with the Warburg effect. Lactic acidosis correlates with cancer malignancy, and the benefit it offers to tumours has been the subject of numerous hypotheses. Strikingly, lactic acidosis enhances cancer cell survival to environmental glucose depletion by repressing high-rate glycolysis and lactic fermentation, and promoting an oxidative metabolism involving reactivated respiration. We used real-time NMR to evaluate how cytosolic lactate accumulation up to 40Â mM and acidification up to pH 6.5 individually impact glucose consumption, lactate production and pyruvate evolution in isolated cytosols. We used a reductive cell-free system (CFS) to specifically study cytosolic metabolism independently of other Warburg-regulatory mechanisms found in the cell. We assessed the impact of lactate and acidification on the Warburg metabolism of cancer cytosols, and whether this effect extended to different cytosolic phenotypes of lactic fermentation and cancer. We observed that moderate acidification, independently of lactate concentration, drastically reduces the glucose consumption rate and halts lactate production in different lactic fermentation phenotypes. In parallel, for Warburg-type CFS lactate supplementation induces pyruvate accumulation at control pH, and can maintain a higher cytosolic pyruvate pool at low pH. Altogether, we demonstrate that intracellular acidification accounts for the direct repression of lactic fermentation by the Warburg-associated lactic acidosis
Cell-Free Protein Synthesis Enhancement from Real-Time NMR Metabolite Kinetics: Redirecting Energy Fluxes in Hybrid RRL Systems
A counterintuitive
cell-free protein synthesis (CFPS) strategy,
based on reducing the ribosomal fraction in rabbit reticulocyte lysate
(RRL), triggers the development of hybrid systems composed of RRL
ribosome-free supernatant complemented with ribosomes from different
mammalian cell-types. Hybrid RRL systems maintain translational properties
of the original ribosome cell types, and deliver protein expression
levels similar to RRL. Here, we show that persistent ribosome-associated
metabolic activity consuming ATP is a major obstacle for maximal protein
yield. We provide a detailed picture of hybrid CFPS systems energetic
metabolism based on real-time nuclear magnetic resonance (NMR) investigation
of metabolites kinetics. We demonstrate that protein synthesis capacity
has an upper limit at native ribosome concentration and that lower
amounts of the ribosomal fraction optimize energy fluxes toward protein
translation, consequently increasing CFPS yield. These results provide
a rationalized strategy for further mammalian CFPS developments and
reveal the potential of real-time NMR metabolism phenotyping for optimization
of cell-free protein expression systems
Quantification Annotation in ISO 24617-12, Second Draft
International audienceThis paper describes the continuation of a project that aims at establishing an interoperable annotation scheme for quantification phenomena as part of the ISO suite of standards for semantic annotation, known as the Semantic Annotation Framework. After a break, caused by the Covid-19 pandemic, the project was relaunched in early 2022 with a second working draft, which deals with certain issues in the annotation of quantification in a more satisfactory way than the original first working draft
Human Pancreatic Islets React to Glucolipotoxicity by Secreting Pyruvate and Citrate
Progressive decline in pancreatic beta-cell function is central to the pathogenesis of type 2 diabetes (T2D). Here, we explore the relationship between the beta cell and its nutritional environment, asking how an excess of energy substrate leads to altered energy production and subsequent insulin secretion. Alterations in intracellular metabolic homeostasis are key markers of islets with T2D, but changes in cellular metabolite exchanges with their environment remain unknown. We answered this question using nuclear magnetic resonance-based quantitative metabolomics and evaluated the consumption or secretion of 31 extracellular metabolites from healthy and T2D human islets. Islets were also cultured under high levels of glucose and/or palmitate to induce gluco-, lipo-, and glucolipotoxicity. Biochemical analyses revealed drastic alterations in the pyruvate and citrate pathways, which appear to be associated with mitochondrial oxoglutarate dehydrogenase (OGDH) downregulation. We repeated these manipulations on the rat insulinoma-derived beta-pancreatic cell line (INS-1E). Our results highlight an OGDH downregulation with a clear effect on the pyruvate and citrate pathways. However, citrate is directed to lipogenesis in the INS-1E cells instead of being secreted as in human islets. Our results demonstrate the ability of metabolomic approaches performed on culture media to easily discriminate T2D from healthy and functional islets