Background Colorectal cancer (CRC) can be classified into four molecular subtypes (CMS) among whi... more Background Colorectal cancer (CRC) can be classified into four molecular subtypes (CMS) among which CMS1 is associated with the best prognosis, while CMS4, the mesenchymal subtype, has the worst outcome. Although mitochondria are considered to be hubs of numerous signaling pathways, the study of mitochondrial metabolism has been neglected for many years. Mitochondrial Complex I (CI) plays a dual role, both in energy and reactive oxygen species (ROS) production. However, the possible contribution of CI to tumorigenesis in cancer remains unclear. The purpose of this study was to investigate the CI under the prism of the CMS classification of CRC in ex vivo models. Methods Biochemical dosages, bioenergetics analysis and western-blot were used to characterize CI expression, function and redox balance in LoVo and MDST8 cell lines, belonging to CMS1 and CMS4 subgroups, respectively. Cell proliferation and migration were assessed by xCELLigence technology. Overproduction or scavenging of m...
Inherited fatty acid oxidation diseases in their mild forms often present as metabolic myopathies... more Inherited fatty acid oxidation diseases in their mild forms often present as metabolic myopathies. Carnitine Palmitoyl Transferase 2 (CPT2) deficiency, one such prototypical disorder is associated with compromised myotube differentiation. Here, we show that CPT2-deficient myotubes exhibit defects in focal adhesions and redox balance, exemplified by increased SOD2 expression. We document unprecedented alterations in the cellular prion protein PrP C , which directly arise from the failure in CPT2 enzymatic activity. We also demonstrate that the loss of PrP C function in normal myotubes recapitulates the defects in focal adhesion, redox balance and differentiation hallmarks monitored in CPT2-deficient cells. These results are further corroborated by studies performed in muscles from Prnp-/mice. Altogether, our results unveil a molecular scenario whereby PrP C dysfunction governed by faulty CPT2 activity may drive aberrant focal adhesion turnover and hinder proper myotube differentiation. Our study adds a novel facet to the involvement of PrP C in diverse physiopathological situations.
The mitochondrial fatty acid b-oxidation (FAO) pathway plays a crucial role in ATP production in ... more The mitochondrial fatty acid b-oxidation (FAO) pathway plays a crucial role in ATP production in many tissues with high-energy demand. This is highlighted by the diverse and possibly severe clinical manifestations of inborn fatty acid b-oxidation deficiencies. More than fifteen genetic FAO enzyme defects have been described to date, forming a large group of rare diseases. Inborn FAO disorders are characterized by a high genetic heterogeneity, with a variety of gene mutations resulting in complete or partial loss-of-function of the corresponding enzyme. The panel of observed phenotypes varies from multiorgan failure in the neonate with fatal outcome, up to milder late onset manifestations associated with significant disabilities. Diagnosis of FAO disorders has markedly improved over the last decades, but few treatments are available. The clinical, biochemical, and molecular analysis of these disorders provided new, and sometimes unexpected, data on the organization and regulation of mitochondrial FAO in humans, in various tissues, and at various stages of development. This will be illustrated by examples of FAO defects affecting enzymes of long-chain fatty acid import into the mitochondria, or Lynen helix enzymes. The involvement of the transcriptional network regulating FAO gene expression, in particular the PGC-1a/PPAR axis, as a target for pharmacological therapy of these genetic disorders, will also be discussed.
Change in energy reserves in different segments of the nephron during brief ischemia. Rat kidneys... more Change in energy reserves in different segments of the nephron during brief ischemia. Rat kidneys were made ischemic for 5 to 120 seconds. Segments of individual nephrons were dissected from freeze dried sections and analyzed for ATP, phosphocreatine, glycogen, glucose, glucose-6-phosphate, lactate and creatine kinase. ATP fell most rapidly in proximal convoluted and straight tubules (PCT, PST) and distal convoluted tubules (DCT), and most slowly in glomerulus and papilla. Phosphocreatine levels ranged fivefold and was highest in DCT, where it approached that of brain. Creatine kinase ranged 100-fold with lowest level in PCT, where the ischemic fall in phosphocreatine was so slow as to suggest a function other than that of an energy reserve. Glycogen varied tenfold from modest levels in distal segments to very low levels in PST, and was not used rapidly in any segment. Glucose consumption and lactate production were most rapid in distal portions. High-energy phosphate consumption for the first 7.5 seconds of ischemia, calculated from these data, indicates roughly-equal energy metabolism in proximal and distal segments, with lower levels in papilla, and especially in glomerulus. The absolute values suggest that the in vivo metabolic rate of the nephron continued almost unabated for 5 or 10 seconds of ischemia. The kidney nephron consists of a series of organs with striking differences in structure, function and enzymatic composition. Less is known about differences in energy metabolism, although it is inferred from their enzyme content [1, 2] that proximal segments have a high oxidative metabolism and distal segments, a relatively-high glycolytic metabolism. This inference is supported by in vitro studies of kidney slices from regions enriched in proximal or distal tubules [3]. It has also recently been demonstrated by Bagnasco et al [4] that in vitro lactate production of the distal tubule and collecting ducts far exceeds that of the proximal tubule. Energy metabolism in the kidney is of particular interest because of its exceptionally high value. The kidney shares with brain the highest metabolic rate in the body, (with the exception of maximally working muscle). Probably because of its high metabolic rate, the kidney is particularly sensitive to anoxia and ischemia. Moreover, some parts of the nephron are more sensitive to these insults than others. For example, the medullary thick ascending limb of Henle is particularly susceptible to
S6 kinase (S6K) deletion in metazoans causes small cell size, insulin hypersensitivity, and metab... more S6 kinase (S6K) deletion in metazoans causes small cell size, insulin hypersensitivity, and metabolic adaptations; however, the underlying molecular mechanisms are unclear. Here we show that S6K-deficient skeletal muscle cells have increased AMP and inorganic phosphate levels relative to ATP and phosphocreatine, causing AMP-activated protein kinase (AMPK) upregulation. Energy stress and muscle cell atrophy are specifically triggered by the S6K1 deletion, independent of S6K2 activity. Two known AMPK-dependent functions, mitochondrial biogenesis and fatty acid b-oxidation, are upregulated in S6K-deficient muscle cells, leading to a sharp depletion of lipid content, while glycogen stores are spared. Strikingly, AMPK inhibition in S6K-deficient cells restores cell growth and sensitivity to nutrient signals. These data indicate that S6K1 controls the energy state of the cell and the AMPK-dependent metabolic program, providing a mechanism for cell mass accumulation under high-calorie diet. Cell Metabolism AMPK Activation in S6K Null Cells Cell Metabolism 5, 476-487, June 2007 ª2007 Elsevier Inc. 477 Franç aise contre les Myopathies (to A. Sotiropoulos and M.P.), the Association Nationale de la Recherche (to B.V. and M.P.), and Telethon (to M.S.). S.A. is a recipient of a stipend from Region Ile-de-France and
Role of Catecholamines in the Control of Newborn Kidney Adenine Nucleotide Content
Neonatology, 1987
During the 1 st h of extrauterine life, the adenine nucleotide content of the rat kidney is modif... more During the 1 st h of extrauterine life, the adenine nucleotide content of the rat kidney is modified: the ATP level increases (+30%) while ADP and AMP are lowered (––30 and ––50%, respectively). This leads to a high value of energy charge in the newborn kidney (0.89 vs. 0.80 in the fetus). It was possible to obtain in utero a similar modification of ATP, ADP, AMP concentrations by injections to the fetuses of cAMP, dibutyryl cAMP, or isoprenaline. Conversely, the postnatal changes in adenine nucleotide content could be prevented by administration to the fetus, just before birth, of β- or β1-adrenoreceptor antagonists. Therefore the rise of kidney energy charge following parturition appears to be under hormonal control. Glucagon had no effect on kidney adenine nucleotide content. It is strongly suggested that the catecholamines released at the time of parturition are the triggering factor of this evolution.
ObjectiveAlthough mitochondrial DNA (mtDNA) depletion could play a role in nucleoside reverse tra... more ObjectiveAlthough mitochondrial DNA (mtDNA) depletion could play a role in nucleoside reverse transcriptase inhibitor-induced lipoatrophy, poor correlations between fat mtDNA levels and lipoatrophy suggest additional mechanism(s). Stavudine (d4T), zidovudine (AZT) and the thymine catabolite, β-aminoisobutyric acid (BAIBA), but not zalcitabine (ddC) or didanosine (ddI), can increase fatty acid oxidation in liver mitochondria and plasma ketone bodies in mice. Since fat oxidation in non-adipose tissue can influence body adiposity, we sought to determine whether d4T, AZT and BAIBA can cause lipoatrophy in mice by this catabolic mechanism.MethodsLean or obese ob/ob mice were treated for 6 weeks with d4T, AZT or BAIBA, and lean mice with ddC or ddI. Body fat mass was assessed by dual energy X-ray absorptiometry, and mtDNA by Slot blot hybridization in epididymal fat.ResultsWhereas ddC or ddI did not change plasma β-hydroxybutyrate and body fat mass, d4T, AZT and BAIBA increased plasma β-h...
Patients with autism spectrum disorder (ASD) may have an increase in blood acyl-carnitine (AC) co... more Patients with autism spectrum disorder (ASD) may have an increase in blood acyl-carnitine (AC) concentrations indicating a mitochondrial fatty acid β-oxidation (mtFAO) impairment. However, there are no data on systematic mtFAO analyses in ASD. We analyzed tritiated palmitate oxidation rates in fibroblasts from patients with ASD before and after resveratrol (RSV) treatment, according to methods used for the diagnosis of congenital defects in mtFAO. ASD participants (N = 10, 60%; male; mean age (SD) 7.4 (3.2) years) were divided in two age-equivalent groups based on the presence (N = 5) or absence (N = 5) of elevated blood AC levels. In addition, electron transport chain (ETC) activity in fibroblasts and muscle biopsies and clinical characteristics were compared between the ASD groups. Baseline fibroblast mtFAO was not significantly different in patients in comparison with control values. However, ASD patients with elevated AC exhibited significantly decreased mtFAO rates, muscle ETC ...
Journal of the American Society of Nephrology, 2001
The ␣ isoform of peroxisome proliferator-activated receptor (PPAR␣), which is highly expressed in... more The ␣ isoform of peroxisome proliferator-activated receptor (PPAR␣), which is highly expressed in the kidney, can stimulate the expression of genes that are involved in fatty acid catabolism and therefore might be involved in the control of renal fatty acid -oxidation. PPAR␣ expression and its regulation in the immature kidney are not well documented. This study delineated the developmental pattern of PPAR␣ expression in the rat kidney cortex and the medulla between postnatal days 10 and 30 and investigated the role of glucocorticoids in regulating PPAR␣ expression. In the cortex, PPAR␣ mRNA and protein increased 2-and 1.8-fold, respectively, from 10 to 21 d and then decreased 1.5-and 2.4-fold from 21 to 30 d. In the medulla, PPAR␣ mRNA and protein increased continuously 3.3-and 2.4-fold, respectively. It is shown here that acute treatment by dexamethasone of 10-d-old rats precociously induced a 4-to 6-fold increase in PPAR␣ mRNA and a 1.8-fold increase in protein within 6 h in each part of the
and/or their next of kin were informed, and written consent authorizing the use of biological sam... more and/or their next of kin were informed, and written consent authorizing the use of biological samples was documented in the medical records of the patients by the investigator. The observational study Myelochondria is registered under the ClinicalTrials.gov identifier NCT04439617. General methods statements. No samples, mice, or studies were removed from the analyses, with the exception of unexpected premature death during CLP or i.p. LPS injection experiments. Experiments were not blinded and samples were not randomized in this study. Tissue culture samples were evaluated for mycoplasma contamination.
Certaines anomalies de la β-oxydation mitochondriale des acides gras (β-OAG) apparaissent jouer u... more Certaines anomalies de la β-oxydation mitochondriale des acides gras (β-OAG) apparaissent jouer un rôle majeur dans la pathogenèse de plusieurs maladies communes (diabète, obésité, maladies cardiaques). Des déficits génétiques touchant la β-OAG sont également à l’origine d’un ensemble de maladies rares de phénotypes très variables, allant de défaillances cardio-hépatiques fatales chez le nourrisson à des myopathies chez l’adulte. Ces différentes pathologies sont révélatrices du rôle clé de la β-OAG dans plusieurs organes à forts besoins en ATP (cœur, muscle, foie, rein). Des données récentes suggèrent que la β-OAG participerait également à d’autres fonctions complexes (modifications de la chromatine, contrôle de l’activité de cellules souches, devenir de cellules cancéreuses).
Exercise-Induced Metabolic Benefits in SMA of respiratory chain I, II, and IV complexes for equal... more Exercise-Induced Metabolic Benefits in SMA of respiratory chain I, II, and IV complexes for equal amount of mitochondria and complexes expression and (2) a significant decline in mitochondrial maximal oxygen consumption, were reduced by both exercise programs. Most of the beneficial effects were obtained with the high-intensity swimming protocol. Taking together, our data support the hypothesis that active physical exercise, including high-intensity protocols, induces metabolic adaptations at both systemic and cellular levels, providing further evidence for its use in association with SMN-overexpressing therapies, in the long-term care of SMA patients.
Carnitine palmitoyl transferase 2 (CPT2) deficiency is one of the most common inherited fatty aci... more Carnitine palmitoyl transferase 2 (CPT2) deficiency is one of the most common inherited fatty acid oxidation (FAO) defects and represents a prototypical mitochondrial metabolic myopathy. Recent studies have suggested a pivotal role of adenosine monophosphate-activated protein kinase (AMPK) in skeletal muscle plasticity and mitochondrial homeostasis. Thus, we tested the potential of GSK773, a novel direct AMPK activator, to improve or correct FAO capacities in muscle cells from patients harboring various mutations. We used controls' and patients' myotubes and studied the parameters of FAO metabolism, of mitochondrial quantity and quality and of differentiation. We found that AMPK is constitutively activated in patients' myotubes, which exhibit both reduced FAO and impaired differentiation. GSK773 improves or corrects several metabolic hallmarks of CPT2 deficiency (deficient FAO flux and C16-acylcarnitine accumulation) by upregulating the expression of CPT2 protein. Beneficial effects of GSK773 are also likely due to stimulation of mitochondrial biogenesis and induction of mitochondrial fusion, by decreasing dynamin-related protein 1 and increasing mitofusin 2. GSK773 also induces a shift in myosin heavy chain isoforms toward the slow oxidative type and, therefore, fully corrects the differentiation process. We establish, through small interfering RNA knockdowns and pharmacological approaches, that these GSK773 effects are mediated through peroxisome proliferator-activated receptor gamma co-activator 1-alpha, reactive oxygen species and p38 mitogen-activated protein kinase, all key players of skeletal muscle plasticity. GSK773 recapitulates several important features of skeletal muscle adaptation to exercise. The results show that AMPK activation by GSK773 evokes the slow, oxidative myogenic program and triggers beneficial phenotypic adaptations in FAO-deficient myotubes. Thus, GSK773 might have therapeutic potential for correction of CPT2 deficiency.
Mitochondrial fatty acid oxidation (FAO) and respiratory chain (RC) defects form a large group of... more Mitochondrial fatty acid oxidation (FAO) and respiratory chain (RC) defects form a large group of inherited monogenic disorders sharing many common clinical and pathophysiological features, including disruption of mitochondrial bioenergetics, but also, for example, oxidative stress and accumulation of noxious metabolites. Interestingly, several transcription factors or co-activators exert transcriptional control on both FAO and RC genes, and can be activated by small molecules, opening to possibly common therapeutic approaches for FAO and RC deficiencies. Here, we review recent data on the potential of various drugs or small molecules targeting pivotal metabolic regulators: peroxisome proliferator activated receptors (PPARs), sirtuin 1 (SIRT1), AMP-activated protein kinase (AMPK), and protein kinase A (PKA)) or interacting with reactive oxygen species (ROS) signaling, to alleviate or to correct inborn FAO or RC deficiencies in cellular or animal models. The possible molecular mechan...
Autism spectrum disorder (ASD) is currently diagnosed according to behavioral criteria. Biomarker... more Autism spectrum disorder (ASD) is currently diagnosed according to behavioral criteria. Biomarkers that identify children with ASD could lead to more accurate and early diagnosis. ASD is a complex disorder with multifactorial and heterogeneous etiology supporting recognition of biomarkers that identify patient subsets. We investigated an easily testable blood metabolic profile associated with ASD diagnosis using high throughput analyses of samples extracted from dried blood spots (DBS). A targeted panel of 45 ASD analytes including acyl-carnitines and amino acids extracted from DBS was examined in 83 children with ASD (60 males; age 6.06 ± 3.58, range: 2-10 years) and 79 matched, neurotypical (NT) control children (57 males; age 6.8 ± 4.11 years, range 2.5-11 years). Based on their chronological ages, participants were divided in two groups: younger or older than 5 years. Two-sided T-tests were used to identify significant differences in measured metabolite levels between groups. Näive Bayes algorithm trained on the identified metabolites was used to profile children with ASD vs. NT controls. Of the 45 analyzed metabolites, nine (20%) were significantly increased in ASD patients including the amino acid citrulline and acyl-carnitines C2, C4DC/C5OH, C10, C12, C14:2, C16, C16:1, C18:1 (P: < 0.001). Näive Bayes algorithm using acylcarnitine metabolites which were identified as significantly abnormal showed the highest performances for classifying ASD in children younger than 5 years (n: 42; mean age 3.26 ± 0.89) with 72.3% sensitivity (95% CI: 71.3;73.9), 72.1% specificity (95% CI: 71.2;72.9) and a diagnostic odds ratio 11.25 (95% CI: 9.47;17.7). Re-test analyses as a measure of validity showed an accuracy of 73% in children with ASD aged ≤5 years. This easily testable, non-invasive profile in DBS may support recognition of metabolic ASD individuals aged ≤5 years and represents a potential complementary tool to improve diagnosis at earlier stages of ASD development.
Carnitine palmitoyltransferase-2 () is a mitochondrial enzyme involved in long-chain fatty acid e... more Carnitine palmitoyltransferase-2 () is a mitochondrial enzyme involved in long-chain fatty acid entry into mitochondria for their β-oxidation and energy production. Two phenotypes are associated with the extremely reducedactivity in genetically deficient patients: neonatal lethality or, in milder forms, myopathy. Resveratrol (RSV) is a phytophenol produced by grape plant in response to biotic or abiotic stresses that displays anti-oxidant properties, in particular through AP-1, NFκB, STAT-3, and COX pathways. Some beneficiary effects of RSV are due to its modulation of microRNA (miRNA) expression. RSV can enhance residualactivities in human fibroblasts derived from-deficient patients and restores normal fatty acid oxidation rates likely through stimulation of mitochondrial biogenesis. Here, we report changes in miRNA expression linked to-deficiency, and we identify miRNAs whose expression changed following RSV treatment of control or-deficient fibroblasts isolated from patients. Our...
Reactive oxygen species (ROS) modify proteins and lipids leading to deleterious outcomes. Thus, m... more Reactive oxygen species (ROS) modify proteins and lipids leading to deleterious outcomes. Thus, maintaining their homeostatic levels is vital. This study highlights the endogenous role of LXRs (LXRα and β) in the regulation of oxidative stress in peripheral nerves. We report that the genetic ablation of both LXR isoforms in mice (LXRdKO) provokes significant locomotor defects correlated with enhanced anion superoxide production, lipid oxidization and protein carbonylation in the sciatic nerves despite the activation of Nrf2-dependant antioxidant response. Interestingly, the reactive oxygen species scavenger N-acetylcysteine counteracts behavioral, electrophysical, ultrastructural and biochemical alterations in LXRdKO mice. Furthermore, Schwann cells in culture pretreated with LXR agonist, TO901317, exhibit improved defenses against oxidative stress generated by tert-butyl hydroperoxide, implying that LXRs play an important role in maintaining the redox homeostasis in the peripheral ...
Very-long chain acyl-CoA dehydrogenase deficiency (VLCADD) is a clinically heterogeneous disorder... more Very-long chain acyl-CoA dehydrogenase deficiency (VLCADD) is a clinically heterogeneous disorder with three major phenotypes: severe neonatal/infantile, milder childhood and late onset myopathic. VLCADD is genetically heterogeneous with numerous pathogenic mutations and variants of uncertain significance. VLCADD is included in many newborn screening programs but these suffer from high false positive rates, primarily due to positive screens in heterozygotes. Separating these and newborns with two low-risk "mild" variants from clinically at risk patients can be problematic, as clinical and biochemical markers are often unreliable, particularly in stable neonates. We have measured fibroblast fatty acid oxidation flux using [9,10-H 3 ]myristic acid and [9,10-H 3 ]oleic acid from 69 clinically presenting VLCADD patients including myopathic and infantile phenotypes and 13 positive newborn screened patients. We also measured fibroblast VLCADD enzyme activity by UV-HPLC detection of product in a subset of patients and compared these results to oleate FAO-flux. Fibroblast enzyme assay by UV-HPLC detection failed to clearly discriminate between some clinically presenting VLCADD patient cell lines and cell lines from some simple heterozygotes. FAO-flux clearly discriminated between clinically presenting VLCADD patients and the false positive screened patients. FAO-flux at 37 • C provides information as to the likely clinical phenotype but FAO-flux at 41 • C is the best discriminator for identifying clinically at risk patients.
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Papers by Jean Bastin