Biology subjects

Mithieux, G.

Publications and source records attributed to Mithieux, G..

8 recordsLinked to original sources

bioRxiv2026

Contributions of the gut microbiota and intestinal gluconeogenesis to metabolic adaptations in a mouse model of anorexia nervosa.

Anorexia nervosa is a metabolic-psychiatric disorder characterized by severe food restriction, often accompanied by hyperactivity, associated with high mortality and the lack of specific pharmacological treatment. Despite a marked energy deficit, patients paradoxically maintain euglycemia, suggesting adaptations in energy homeostasis. This study aims to characterize the interactions between food restriction, the gut microbiota and peripheral organs in a mouse model mimicking anorexia nervosa. Our results show that food-restricted mice exhibit improved glucose tolerance and increased expression of the gluconeogenic genes G6pc and Pck1 in the intestine, suggesting an adaptation in endogenous glucose production. Gut microbiota analysis reveals a marked shift in composition in food-restricted mice, with an increase in the Lachnospiraceae and Marinifilaceae families and a decrease in Lactobacillaceae. These changes are associated with metabolic parameters such as glycemia, body weight, and GLP-1 levels. Transfer of microbiota from food-restricted mice into control mice improves glucose tolerance and increases the gluconeogenic gene expression. Furthermore, the improvement in glucose tolerance is abolished in mice lacking intestinal gluconeogenesis, suggesting that intestinal gluconeogenesis is required for the effects of the FR microbiota on glucose homeostasis. Overall, these findings highlight a complex metabolic adaptation in a mouse model of anorexia nervosa, involving interactions between the gut microbiota, intestinal gluconeogenesis and maintenance of energy homeostasis.

physiology↗

bioRxiv2025

A bioenergetic basis for multiorgan dysfunction in sepsis

Sepsis is a life-threatening multiorgan dysfunction that develops from a maladaptive host response to infection1. With an estimated 49 million cases per year and [~]11 million related deaths2, sepsis is a global WHO health priority3. Failure to overcome sepsis morbidity and lethality4,5 calls for alternative therapeutic approaches6-8. Here we report that adipocyte lipolysis is vital to prevent the pathogenesis of sepsis in mice. This protective response is evolutionary conserved, producing a plasma lipidomic profile9,10 that reflects on the severity of clinical sepsis. Mechanistically, adipocyte lipolysis fuels energy metabolism to sustain adaptive thermoregulation to infection, via insulin production and insulin receptor (INSR) signaling in adipocytes. This metabolic-based defense strategy does not impact on bacterial burden, establishing disease tolerance to infection11-14. In conclusion, adipocyte lipolysis induces insulin to rewire energy metabolism and support organ function in response to infection.

pathology↗

bioRxiv2025

Reducing the CAV1-dependent trafficking of G6PC1 in the liver protects against the development of type 2 diabetes

Targeting hepatic gluconeogenesis is an efficient strategy to counteract the development of type 2 diabetes. Hepatic glucose production into the bloodstream is controlled by the GLUT2 transporter and a vesicular pathway dependent on Caveolin-1 (CAV1) involving G6PC1 location at the plasma membrane. We hypothesized that decreasing hepatic gluconeogenesis by targeting CAV1 specifically in the liver (L.Cav1-/- mice) improves energy and glucose metabolism in diabetic mice. Here we show that the absence of hepatic CAV1 increases insulin sensitivity, glucose tolerance and decreases fasting hyperglycemia and hyperinsulinemia in mice feeding a high fat high sucrose diet (HFHS diet). The decrease in insulin sensitivity takes place also in L.Cav1-/- mice feeding a standard diet (STD diet). Moreover, we demonstrated an improvement of glycemic control when hepatic Cav1 is deleted in previously prediabetic mice. In parallel, the absence of CAV1 in the liver reduces body weight gain and lipid intestinal absorption. Together these findings highlight that the vesicular pathway of glucose production represents a promising therapeutic target in the prevention of type 2 diabetes.

physiology↗

bioRxiv2023

Imprinted cell memory in glycogen storage disorder 1a

Glycogen storage disorder type 1a (GSD1a) is caused by loss-of-function mutations in the catalytic subunit of glucose-6-phosphatase enzyme (G6PC1) in the liver, kidney and intestine exclusively. Here we show the surprising results that while not expressing G6PC1, primary skin fibroblasts isolated from GSD1a patients skin biopsies preserve a distinctive disease phenotype irrespective of the different culture conditions under which they grow. This discovery was initially made by phenotypic image-based high content analysis (HCA). Deeper analysis into this disease phenotype, revealed impaired lysosomal and mitochondrial functions in GSD1a cells, which were driven by a transcriptional dysregulation of the NAD+/NADH-Sirt-1-TFEB regulatory axis. This dysregulation impacts the normal balance between mitochondrial biogenesis and mitophagy in the patients cells. The distinctive GSD1a fibroblasts phenotype involves elevated H3 histone acetylation, global DNA hypomethylation, differences in the chromatin accessibility and different RNA-seq and metabolomic profiles, all of which suggesting that in some way a distinctive disease cell phenotype is programmed in these cells in vivo and that this phenotype is maintained in vitro. Supporting this notion, reversing H3 acetylation in these cells erased the original cellular phenotype in GSD1a cells. Remarkably, GHF201, an established glycogen reducing molecule, which ameliorated GSD1a pathology in a liver-targeted inducible L.G6pc- knockout mouse model, also reversed impaired cellular functions in GSD1a patients fibroblasts. Altogether, this experimental evidence strongly suggests that GSD1a fibroblasts express a strong and reversible disease phenotype without expressing the causal G6PC1 gene.

molecular biology↗

bioRxiv2021

Intestinal Gluconeogenesis Regulates Brown and White Adipose Tissues Functions in mice

ObjectiveIntestinal gluconeogenesis, via the initiation of a gut-brain nervous circuit, accounts for the metabolic benefits linked to dietary proteins or fermentable fibre in rodents and has been positively correlated with the rapid amelioration of body weight after gastric bypass surgery in obese humans. In particular, the activation of intestinal gluconeogenesis moderates the development of hepatic steatosis accompanying obesity. In this study, we investigated the specific effects of intestinal gluconeogenesis on adipose tissue metabolism, independently of its induction by nutritional manipulation. MethodsWe used two transgenic mouse models of suppression or overexpression of G6PC, the catalytic subunit of glucose-6 phosphatase, the key enzyme of endogenous glucose production, specifically in the intestine. ResultsUnder a hypercaloric diet, mice with a genetic overexpression of intestinal gluconeogenesis showed a lower adiposity and higher thermogenic capacities than wild-type mice, featuring marked browning of white adipose tissue and prevention of the whitening of brown adipose tissue. Suppression of sympathetic nervous signalling in brown adipose tissue impairs the activation of thermogenesis. Conversely, mice with genetic suppression of intestinal gluconeogenesis exhibit an increase in adiposity under standard diet, associated with a decreased expression of markers of thermogenesis in both the brown and white adipose tissues. ConclusionIntestinal gluconeogenesis is sufficient in itself to activate the sympathetic nervous system and prevent the expansion and the metabolic alterations of brown and white adipose tissues metabolism under high calorie diet, thus preventing the development of obesity. These data increase knowledge of the mechanisms of weight reduction in gastric bypass surgery and pave the way of new approaches to prevent or cure obesity.

physiology↗

bioRxiv2021

A HYPOMETABOLIC DEFENSE STRATEGY AGAINST PLASMODIUM INFECTION

Hypoglycemia is a clinical hallmark of severe malaria, the often-lethal presentation of Plasmodium falciparum infection of humans. Here we report that mice reduce blood glucose levels in response to Plasmodium infection via a coordinated response whereby labile heme, an alarmin produced via hemolysis, induces anorexia and represses hepatic glucose production (HGP). While protective against unfettered immune-mediated inflammation, organ damage and anemia, when sustained over time heme-driven repression of HGP can progress towards hypoglycemia, compromising host energy expenditure and thermoregulation. This hypometabolic state arrests the development of asexual stages of Plasmodium spp., which undergo pyknosis and develop mitochondrial dysfunction. In response, Plasmodium activates a transcriptional program reducing its virulence and inducing sexual differentiation towards the production of transmissible gametocytes. We infer that malaria-associated hypoglycemia represents a trade-off of an evolutionarily conserved defense strategy restricting Plasmodium spp. from accessing host-derived glucose and balancing parasite virulence and transmission.

immunology↗

bioRxiv2019

Atrial natriuretic peptide orchestrates a coordinated physiological response to fuel non shivering thermogenesis

Atrial natriuretic peptide (ANP) is a cardiac hormone controlling blood volume and arterial pressure in mammals. It is unclear whether and how ANP controls cold-induced thermogenesis in vivo. Here we show that acute cold exposure induces cardiac ANP secretion in mice and humans. Genetic inactivation of ANP promotes cold intolerance and suppresses about half of cold-induced brown adipose tissue (BAT) activation in mice. While white adipocytes are resistant to ANP-mediated lipolysis at thermoneutral temperature in mice, cold exposure renders white adipocytes fully responsive to ANP to activate lipolysis and a thermogenic program, a physiological response which is dramatically suppressed in ANP null mice. ANP deficiency also blunts liver triglycerides and glycogen metabolism thus impairing fuel availability for BAT thermogenesis. ANP directly increases mitochondrial uncoupling and thermogenic genes expression in human white and brown adipocytes. Together, these results indicate that ANP is a major physiological trigger of BAT thermogenesis upon cold exposure in mammals.

physiology↗

bioRxiv2017

Inhibition of granulocyte ROS production by opioids prevents regeneration

Inhibition of regeneration and induction of healing are classic outcomes of tissue repair in adult mammals. Here, by using gain and loss of function experiments, we demonstrate that both endogenous and exogenous opioids prevent tissue regeneration in adults, by inhibiting the early reactive oxygen species (ROS) production occurring after lesion and required for regeneration. These effects can be overcome and regeneration induced by the use of an opioid antagonist. These results, obtained in both gold-standard adult zebrafish and a newly-developed model of regeneration in adult mammals, demonstrate that this mechanism can be considered as a general paradigm in vertebrates. In addition, we show that opioids act via signaling through peripheral mu-receptors expressed on granulocytes. This work clearly demonstrates the deleterious role of opioids on tissue regeneration through the control of ROS production in vertebrates and thus questions about opioid-based analgesia in perioperative care.

physiology↗