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The Arctic sea-ice-scape is rapidly transforming. Increasing light penetration will initiate earlier seasonal primary production. This earlier growing season may be accompanied by an increase in ice algae and phytoplankton biomass, augmenting the emission of dimethylsulfide and capture of carbon dioxide. Secondary production may also increase on the shelves, although the loss of sea ice exacerbates the demise of sea-ice fauna, endemic fish and megafauna. Sea-ice loss may also deliver more methane to the atmosphere, but warmer ice may release fewer halogens, resulting in fewer ozone depletion events. The net changes in carbon drawdown are still highly uncertain. Despite large uncertainties in these assessments, we expect disruptive changes that warrant intensified long-term observations and modelling efforts., info:eu-repo/semantics/published

A presente proposição reivindica o estudo como elemento constitutivo e basilar do ofício de professor. Neste texto, nos dedicaremos a pensá-lo a partir de atividades desenvolvidas no escopo da formação docente inicial, nossa área de atuação (uma, professora de um curso de licenciatura em uma universidade pública e a outra, professora de uma instituição escolar pública de ensino fundamental e médio). Tal atuação nos possibilita indicar, em um primeiro momento, certas incongruências no discurso acerca da profissionalização/ burocratização do professor. Neste sentido, destacamos que a formação docente inicial tem cada vez mais se fundamentado em uma lógica de aprendizagem, de desenvolvimento de competências e habilidades voltadas, na maioria das vezes, à garantia de inserção no mercado de trabalho e atuação profissional adaptada a lógicas produtivistas. Diante disto, nos propomos a pensar, no interior de uma noção de skholé – de um tempo livre e de um espaço público -, as possibilidades de estudo do ofício não somente em seus conteúdos específicos e metodologias, mas, especialmente, através de seus gestos, maneiras e modos de fazer. Por isso o foco não está num método docente, mas na ativação de uma experimentação desenvolvida através de observações, pensamentos e práticas que coloquem a escola – e por conseguinte a sala de aula - como matéria de estudo. Portanto o estágio, esta etapa fundamental da formação docente inicial, constitui-se em um tempo e espaço de atenção à escola. Tem por assunto o ofício do professor e por matéria os elementos que constituem este ofício. Para tanto, amparamo-nos particularmente nos escritos de Jan Masschelein e Marteen Simons sobre a noção de escolar e de Jorge Larrosa, sobre o ofício de professor.

We report on methane (CH4) stable isotope (δ13C and δ2H) measurements from landfast sea ice collected near Barrow (Utqiagvik, Alaska) and Cape Evans (Antarctica) over the winter-to-spring transition. These measurements provide novel insights into pathways of CH4 production and consumption in sea ice. We found substantial differences between the two sites. Sea ice overlying the shallow shelf of Barrow was supersaturated in CH4 with a clear microbial origin, most likely from methanogenesis in the sediments. We estimated that in situ CH4 oxidation consumed a substantial fraction of the CH4 being supplied to the sea ice, partly explaining the large range of isotopic values observed (δ13C between –68.5 and –48.5 ‰ and δ2H between –246 and –104 ‰). Sea ice at Cape Evans was also supersaturated in CH4 but with surprisingly high δ13C values (between –46.9 and –13.0 ‰), whereas δ2H values (between –313 and –113 ‰) were in the range of those observed at Barrow. These are the first measurements of CH4 isotopic composition in Antarctic sea ice. Our data set suggests a potential combination of a hydrothermal source, in the vicinity of the Mount Erebus, with aerobic CH4 formation in sea ice, although the metabolic pathway for the latter still needs to be elucidated. Our observations show that sea ice needs to be considered as an active biogeochemical interface, contributing to CH4 production and consumption, which disputes the standing paradigm that sea ice is an inert barrier passively accumulating CH4 at the ocean-atmosphere boundary.

A chamada temática “Gênero e Religiosidades: resistências e modos de vida” foi proposta com a intenção de congregar trabalhos atentos a práticas e experiências diversas de vida religiosa a partir das categorias gênero e resistência. Consideramos que a pertinência da proposição se fundamenta no exercício de pensar as múltiplas dimensões que conformam nosso Tempo Presente, particularmente no que diz respeito às tensões, imposições e reinvenções quanto às questões de gênero, categoria central para analisar práticas e experiências religiosas.

Resumen basado en el de la publicación Se reivindica el estudio como elemento constitutivo y basilar del oficio de profesor. Se dedican a pensarlo a partir de actividades desarrolladas en el ámbito de la formación docente inicial, el área de actuación (una profesora de un curso de licenciatura en una universidad pública y, la otra, profesora de una institución escolar pública de enseñanza secundaria y bachillerato). Tal actuación posibilita indicar, en un primer momento, ciertas incongruencias en el discurso acerca de la profesionalización / burocratización del profesor. ESP

International audience; Red wine polyphenol extracts (polyphenols) ameliorate cardiovascular and metabolic disorders associated with obesity. Previously, we demonstrated that the alpha isoform of estrogen receptor (ERα) triggers the vascular protection of polyphenols. Here, we investigated the contribution of ERα on the effects of polyphenols on cardiovascular and metabolic alterations associated with obesity. We used ovariectomized wild type or ERα-deficient mice receiving standard (SD) or western (WD) diets, or SD and WD containing polyphenols (SD+polyphenols and WD+polyphenols, respectively) over a 12-week period. Body weight was measured during treatment. Echocardiography examination was performed before sacrifice. Blood and tissues were sampled for biochemical and functional analysis with respect to nitric oxide (NO(•)) and oxidative stress. Vascular reactivity and liver mitochondrial complexes were analyzed. In WD-fed mice, polyphenols reduced adiposity, plasma triglycerides and oxidative stress in aorta, heart, adipose and liver tissues and enhanced NO(•) production in aorta and liver. ERα deletion prevented or reduced the beneficial effects of polyphenols, especially visceral adiposity, aortic and liver oxidative stresses and NO(•) bioavailability. ERα deletion, however, had no effect on polyphenol's ability to decrease the fat accumulation and oxidative stress of subcutaneous adipose tissue. Also, ERα deletion did not modify the decrease of ROS levels induced by polyphenols treatment in the visceral adipose tissue and heart from WD-fed mice. Dietary supplementation of polyphenols remarkably attenuates features of metabolic syndrome; these effects are partially mediated by ERα-dependent mechanisms. This study demonstrates the therapeutic potential of this extract in metabolic and cardiovascular alterations linked to excessive energy intake.

International audience; Heme biosynthesis begins in the mitochondrion with the formation of delta-aminolevulinic acid (ALA). In acute intermittent porphyria, hereditary tyrosinemia type I and lead poisoning patients, ALA is accumulated in plasma and in organs, especially the liver. These diseases are also associated with neuromuscular dysfunction and increased incidence of hepatocellular carcinoma. Many studies suggest that this damage may originate from ALA-induced oxidative stress following its accumulation. Using theMnSOD as an oxidative stress marker, we showed here that ALA treatment of cultured cells induced ROS production, increasing with ALA concentration. The mitochondrial energetic function of ALA-treated HepG2 cells was further explored. Mitochondrial respiration and ATP content were reduced compared to control cells. For the 300μM treatment, ALA induced a mitochondrial mass decrease and a mitochondrial network imbalance although neither necrosis nor apoptosis were observed. The up regulation of PGC-1, Tfam and ND5 genes was also found; these genes encode mitochondrial proteins involved in mitochondrial biogenesis activation and OXPHOS function. We propose that ALA may constitute an internal bioenergetic signal, which initiates a coordinated upregulation of respiratory genes, which ultimately drives mitochondrial metabolic adaptation within cells. The addition of an antioxidant, Manganese(III) tetrakis(1-methyl-4-pyridyl)porphyrin (MnTMPyP), resulted in improvement of maximal respiratory chain capacity with 300μM ALA. Our results suggest that mitochondria, an ALA-production site, are more sensitive to pro-oxidant effect of ALA, and may be directly involved in pathophysiology of patients with inherited or acquired porphyria.

Acetylcholine regulates hormone secretion from the pancreatic islet and is thus crucial for glucose homeostasis. Little is known, however, about acetylcholine (cholinergic) signaling in the human islet. We recently reported that in the human islet, acetylcholine is primarily a paracrine signal released from α-cells rather than primarily a neural signal as in rodent islets. In this study, we demonstrate that the effects acetylcholine produces in the human islet are different and more complex than expected from studies conducted on cell lines and rodent islets. We found that endogenous acetylcholine not only stimulates the insulin-secreting β-cell via the muscarinic acetylcholine receptors M3 and M5, but also the somatostatin-secreting δ-cell via M1 receptors. Because somatostatin is a strong inhibitor of insulin secretion, we hypothesized that cholinergic input to the δ-cell indirectly regulates β-cell function. Indeed, when all muscarinic signaling was blocked, somatostatin secretion decreased and insulin secretion unexpectedly increased, suggesting a reduced inhibitory input to β-cells. Endogenous cholinergic signaling therefore provides direct stimulatory and indirect inhibitory input to β-cells to regulate insulin secretion from the human islet.

This paper describes a facile, efficient, and clean synthesis of various pyrazolones by employing T3P® as a catalyst and performing the reaction under microwave irradiation. This two-step, one-pot reaction proceeded readily and tolerated a variety of functional groups. A wide range of pyrazolone derivatives were obtained in good to excellent yields.

This Letter describes a convenient, efficient, and clean synthesis of various tetrahydro-β-carbolines catalyzed by propane phosphonic acid anhydride T3P® under microwave irradiation.

Hedgehog (Hh) is a critical regulator of adipogenesis. Extracellular vesicles are natural Hh carriers, as illustrated by activated/apoptotic lymphocytes specifically shedding microparticles (MP) bearing the morphogen (MPHh+). We show that MPHh+ inhibit adipocyte differentiation and orientate mesenchymal stem cells towards a pro-osteogenic program. Despite a Smoothened (Smo)-dependency, MPHh+ anti-adipogenic effects do not activate a canonical Hh signalling pathway in contrast to those elicited either by the Smo agonist SAG or recombinant Sonic Hedgehog. The Smo agonist GSA-10 recapitulates many of the hallmarks of MPHh+ anti-adipogenic effects. The adipogenesis blockade induced by MPHh+ and GSA-10 was abolished by the Smo antagonist LDE225. We further elucidate a Smo/Lkb1/Ampk axis as the non-canonical Hh pathway used by MPHh+ and GSA-10 to inhibit adipocyte differentiation. Our results highlight for the first time the ability of Hh-enriched MP to signal via a non-canonical pathway opening new perspectives to modulate fat development.

Acetylcholine is a neurotransmitter that plays a major role in the function of the insulin secreting pancreatic beta cell1,2. Parasympathetic innervation of the endocrine pancreas, the islets of Langerhans, has been shown to provide cholinergic input to the beta cell in several species1,3,4, but the role of autonomic innervation in human beta cell function is at present unclear. Here we show that, in contrast to mouse islets, cholinergic innervation of human islets is sparse. Instead, we find that the alpha cells of the human islet provide paracrine cholinergic input to surrounding endocrine cells. Human alpha cells express the vesicular acetylcholine transporter and release acetylcholine when stimulated with kainate or a lowering in glucose concentration. Acetylcholine secretion by alpha cells in turn sensitizes the beta cell response to increases in glucose concentration. Our results demonstrate that in human islets acetylcholine is a paracrine signal that primes the beta cell to respond optimally to subsequent increases in glucose concentration. We anticipate these results to revise models about neural input and cholinergic signaling in the endocrine pancreas. Cholinergic signaling within the islet represents a potential therapeutic target in diabetes5, highlighting the relevance of this advance to future drug development.

Extracellular ATP has been proposed as a paracrine signal in rodent islets, but it is unclear what role ATP plays in human islets. We now show the presence of an ATP signaling pathway that enhances the human β cell's sensitivity and responsiveness to glucose fluctuations. By using in situ hybridization, RT-PCR, immunohistochemistry, and Western blotting as well as recordings of cytoplasmic-free Ca 2+ concentration, [Ca 2+ ] i , and hormone release in vitro, we show that human β cells express ionotropic ATP receptors of the P2X 3 type and that activation of these receptors by ATP coreleased with insulin amplifies glucose-induced insulin secretion. Released ATP activates P2X 3 receptors in the β-cell plasma membrane, resulting in increased [Ca 2+ ] i and enhanced insulin secretion. Therefore, in human islets, released ATP forms a positive autocrine feedback loop that sensitizes the β cell's secretory machinery. This may explain how the human pancreatic β cell can respond so effectively to relatively modest changes in glucose concentration under physiological conditions in vivo.

Mitochondrial biogenesis, which depends on nuclear as well as mitochondrial genes, occurs in response to increased cellular ATP demand. The nuclear transcriptional factors, estrogen-related receptor α (ERRα) and nuclear respiratory factors 1 and 2, are associated with the coordination of the transcriptional machinery governing mitochondrial biogenesis, whereas coactivators of the peroxisome proliferator-activated receptor γ coactivator-1 (PGC-1) family serve as mediators between the environment and this machinery. In the context of proliferating cells, PGC-1-related coactivator (PRC) is a member of the PGC-1 family, which is known to act in partnership with nuclear respiratory factors, but no functional interference between PRC and ERRα has been described so far. We explored three thyroid cell lines, FTC-133, XTC.UC1 and RO 82 W-1, each characterized by a different mitochondrial content, and studied their behavior towards PRC and ERRα in terms of respiratory efficiency. Overexpression of PRC and ERRα led to increased respiratory chain capacity and mitochondrial mass. The inhibition of ERRα decreased cell growth and respiratory chain capacity in all three cell lines. However, the inhibition of PRC and ERRα produced a greater effect in the oxidative cell model, decreasing the mitochondrial mass and the phosphorylating respiration, whereas the nonphosphorylating respiration remained unchanged. We therefore hypothesize that the ERRα–PRC complex plays a role in arresting the cell cycle through the regulation of oxidative phosphorylation in oxidative cells, and through some other pathway in glycolytic cells.

OBJECTIVETo report a case of atazanavir-associated choledocholithiasis in an HIV-infected individual.CASE SUMMARYA 47-year-old treatment-naïve HIV-positive African female presented to the emergency department with a 3-day history of right epigastric pain. Six weeks prior to this episode, she began antiretroviral therapy with a regimen consisting of atazanavir 400 mg and abacavir/lamivudine 600/300 mg once daily. Alanine aminotransferase (766 U/L), aspartate aminotransferase (876 U/L), γ-glutamyltransferase (588 U/L), alkaline phosphatase (348 U/L), and total bilirubin (3.9 mg/dL) levels were elevated. Abdominal ultrasound revealed obstructive choledocholithiasis as well as intra- and extrahepatic biliary dilatation. She underwent a laparoscopic cholecystectomy, which revealed approximately 50 small calculi present in the gallbladder. Since previous ultrasounds had also shown gallstones, an analysis of the extracted calculi was performed to determine the possible association with atazanavir use; low amounts of atazanavir were detected.DISCUSSIONAtazanavir is an inhibitor of the bilirubin-conjugating enzyme UGT1A1 and has been frequently linked to the occurrence of hyperbilirubinemia without complications. This individual experienced hyperbilirubinemia that peaked at hospital presentation after she developed choledocholithiasis and secondary acute hepatitis. Analysis of the extracted gallstones revealed that smaller stones contained a higher content of atazanavir than larger stones, which suggests that atazanavir precipitation may play a role in cholelithiasis, although the mechanism remains unknown. The low yield of atazanavir may be explained by the short, 6-week duration of drug exposure as well as the lack of assay for metabolites. The Naranjo probability scale implicated choledocholithiasis as a possible atazanavir-associated adverse event. This report provides the first published evidence that even short-term use of atazanavir may lead to hyperbilirubinemia with choledocholithiasis and secondary acute hepatitis in HIV-infected adults.CONCLUSIONSAtazanavir should be considered a possible contributor in the development of cholelithiasis or choledocholithiasis, and people with HIV should receive adequate counseling in the recognition of symptoms associated with gallstones. The exact incidence and mechanism still need to be elucidated.

An important feature of glucose homeostasis is the effective release of glucagon from the pancreatic alpha cell. The molecular mechanisms regulating glucagon secretion are still poorly understood. We now demonstrate that human alpha cells express ionotropic glutamate receptors (iGluRs) that are essential for glucagon release. A lowering in glucose concentration results in the release of glutamate from the alpha cell. Glutamate then acts on iGluRs of the AMPA/kainate type, resulting in membrane depolarization, opening of voltage-gated Ca(2+) channels, increase in cytoplasmic free Ca(2+) concentration, and enhanced glucagon release. In vivo blockade of iGluRs reduces glucagon secretion and exacerbates insulin-induced hypoglycemia in mice. Hence, the glutamate autocrine feedback loop endows the alpha cell with the ability to effectively potentiate its own secretory activity. This is a prerequisite to guarantee adequate glucagon release despite relatively modest changes in blood glucose concentration under physiological conditions.

National audience; No abstract available

The Death Associated Protein 3 (DAP3), a GTP-binding constituent of the small subunit of the mitochondrial ribosome, is implicated in the TNFalpha and IFNgamma apoptotic pathways of the cell and is involved in the maintenance of the mitochondrial network. We have investigated the mitochondrial role of DAP3 by analyzing its mRNA and protein expression in transformed and non-transformed cell lines presenting various levels of mtDNA. The 3 mtDNA-less (rho degrees ) cell lines showed a complete absence of DAP3, whereas the mRNA expression was conserved. In HepG2 cells treated with increasing doses of ddCTP, the depletion of mtDNA was accompanied by the reduced expression of DAP3. However, the expression of the corresponding mRNA was maintained, suggesting the existence of a post-transcriptional mechanism responsible for the depletion of the DAP3. Compared to the parental cells, the 3 rho degrees cell lines displayed partial resistance to staurosporin-induced cell death. The absence of pro-apoptotic DAP3 in these mtDNA-less cells could explain their reduced apoptotic capacity. Our results suggest that the mtDNA content plays a role in cell apoptosis by mediating the expression of DAP3.

Thyroid oncocytic adenomas are a class of tumors characterized by the presence of abundant mitochondria. We performed a differential display RT-PCR analysis on two oncocytic adenomas and their paired controls. We then carried out a microarray analysis using the 460 selected, differentially expressed clones on four other oncocytomas and their paired controls. Thirty genes, 12 encoded by mitochondrial DNA and 18 nuclear-encoded, were overexpressed by a factor of at least 2 in the tumors compared with the controls. Seven of the 18 nuclear-encoded genes are involved in protein metabolism: DKFZP434I116, B3GTL, SNX19, RP42, SENP1, UBE2D3, and the CTSB gene, which is known to be particularly deregulated in most thyroid tumors. Other genes are implicated in signal transduction (ITGAV) or tumorigenesis (AF1q). Immunohistochemistry allowed us to confirm overexpression of the ITGAV and CTSB genes at the protein level and showed a marked relocation of the CTSB protein. We confirmed the overexpression of the AF1q oncogene in 56% of 18 oncocytic tumors by quantitative RT-PCR analysis, which attested to the heterogeneity of these tumors. Our results show an increased expression of genes involved in protein metabolism in oncocytoma, the significance of which requires investigation.

BACKGROUND Mitochondrial biogenesis and bioenergetics play an important role in oocyte maturation and embryo development. We have investigated the relationship between defective mitochondrial biogenesis and the lack of oocyte maturity observed during IVF procedures with patients suffering from ovarian dystrophy and ovarian insufficiency. METHODS We used real-time quantitative PCR to quantify mitochondrial DNA (mtDNA) in 116 oocytes obtained from 47 women undergoing the ICSI procedure. We compared the mtDNA content of oocytes from women with a normal ovarian profile with that of oocytes from women with ovarian dystrophy and ovarian insufficiency. RESULTS We found an average of 256,000 +/- 213,000 mitochondrial genomes per cell. The mean mtDNA copy number was not significantly different in ovarian dystrophy compared with controls, but it was significantly lower in oocytes from women with ovarian insufficiency (100,000 +/- 99,000, P < 0.0001). CONCLUSIONS Our results suggest that low mtDNA content is associated with the impaired oocyte quality observed in ovarian insufficiency.

Nuclear mitochondrial pseudogenes (Numts) have been found in the genome of many eukaryote species, including humans. Using a BLAST approach, we found 1105 DNA sequences homologous to mitochondrial DNA (mtDNA) in the August 2001 Goldenpath human genome database. We assembled these sequences manually into 286 pseudogenes on the basis of single insertion events and constructed a chromosomal map of these Numts. Some pseudogenes appeared highly modified, containing inversions, deletions, duplications, and displaced sequences. In the case of four randomly selected Numts, we used PCR tests on cells lacking mtDNA to ensure that our technique was free from genome-sequencing artifacts. Furthermore, phylogenetic investigation suggested that one Numt, apparently inserted into the nuclear genome 25-30 million years ago, had been duplicated at least 10 times in various chromosomes during the course of evolution. Thus, these pseudogenes should be very useful in the study of ancient mtDNA and nuclear genome evolution.

Nature 508, 215–221 (2014); doi:10.1038/nature13181 In this Article, the structure of compound TH650 (4) in Fig. 4a was drawn incorrectly; the correct structure is shown as Fig. 1 to this Corrigendum. Preparative, spectroscopic and biological data associated with this compound are as reported in theArticle, and the error does not influence any of the reported data or interpretations.

This paper describes a facile, efficient, and clean synthesis of various pyrazolones by employing T3P® as a catalyst and performing the reaction under microwave irradiation. This two-step, one-pot reaction proceeded readily and tolerated a variety of functional groups. A wide range of pyrazolone derivatives were obtained in good to excellent yields.

International audience; Delphinidin, an anthocyanin present in red wine, has been reported to exert vasculoprotective properties on endothelial cells, including vasorelaxing and anti-apoptotic effects. Moreover, delphinidin treatment in a rat model of post-ischemic neovascularization has been described to exert anti-angiogenic property. Angiogenesis is an energetic process and VEGF-induced angiogenesis is associated with mitochondrial biogenesis. However, whether delphinidin induces changes in mitochondrial biogenesis has never been addressed.Effects of delphinidin were investigated in human endothelial cells at a concentration described to be anti-angiogenic in vitro (10−2g/l). mRNA expression of mitochondrial biogenesis factors, mitochondrial respiration, DNA content and enzyme activities were assessed after 48h of stimulation.Delphinidin increased mRNA expression of several mitochondrial biogenesis factors, including NRF1, ERRα, Tfam, Tfb2m and PolG but did not affect neither mitochondrial respiration, DNA content nor enzyme activities. In presence of delphinidin, VEGF failed to increase mitochondrial respiration, DNA content, complex IV activity and Akt activation in endothelial cells.These results suggest a possible association between inhibition of VEGF-induced mitochondrial biogenesis through Akt pathway by delphinidin and its anti-angiogenic effect, providing a novel mechanism sustaining the beneficial effect of delphinidin against pathologies associated with excessive angiogenesis such as cancers.

Sodium selenite (Na2SeO3) is the selenium form used in the composition of dietary supplements, and diphenyl diselenide (PhSe)2 is an important intermediate in organic synthesis, which increases the risk of human exposure to this chemical in the workplace. These compounds have been reported to inhibit the cerebral and hepatic aminolevulinic acid dehydratase (ALA-D) in vitro, and now we show that ascorbic acid can reverse some alterations caused by in vivo selenium exposure, but not ALA-D inhibition. The effect of Na2SeO3 or (PhSe)2 and ascorbic acid on selenium distribution, total non-protein thiol, ascorbic acid content (liver and brain) and haemoglobin was also examined. Mice were exposed to 250 micromol/kg (PhSe)2, or 18.75 micromol/kg Na2SeO3 subcutaneously, and to ascorbic acid, twice a day, 1 mmol/kg intraperitonially, for 10 days. Hepatic ALA-D of mice treated with (PhSe)2 was inhibited about 58% and similar results were observed in the animals that received ascorbic acid supplementation (P 0.10). Ascorbic acid treatment decreased significantly the hepatic and cerebral deposition of Se in (PhSe)2-exposed mice (P

Human DAP3 (death-associated protein-3) has been identified as an essential positive mediator of programmed cell death. Structure–function studies have shown previously the N-terminal extremity of the protein to be required in apoptosis induction. Analysis of human DAP3 gene structure predicted 13 exons and subsequent targeting prediction by two software packages (MITOPROT and TargetP) gave a high probability for mitochondrial targeting. The predicted N-terminal targeting structure was also found in the mouse, Drosophila, and C. elegans orthologues with a strong sequence homology between mouse and human. Secondary structure analyses identified α-helical structures typical of mitochondrial target peptides. To confirm experimentally this targeting we constructed a fusion protein with N-terminal human DAP3 upstream of enhanced green fluorescent protein (EGFP). Confocal analysis of transfected human fibroblasts clearly demonstrated EGFP localization exclusive to mitochondria. The positioning of this key apoptotic factor at the heart of the mitochondrial pathway provides exciting insight into its role in programmed cell death.

Lindane (LD) is a persistent environmental pollutant that has been the subject of several toxicological studies. However, concentrations used in most of the reported studies were relatively higher than those found in the blood of the contaminated area residents and effects of low concentrations remain poorly investigated. Moreover, effects on cell metabolism and mitochondrial function of exposure to LD have received little attention. This study was designed to explore the effects of low concentrations of LD on cellular metabolism and mitochondrial function, using the hepatocarcinoma cell line HepG2. Cells were exposed to LD for 24, 48 and 72 h and different parameters linked with mitochondrial regulation and energy metabolism were analyzed. Despite having any impact on cellular viability, exposure to LD at plasmatic concentrations led to an increase of maximal respiratory capacity, complex I activity, intracellular ATP and NO release but decreased uncoupled respiration to ATP synthesis and medium lactate levels. In addition, LD exposure resulted in the upregulation of mitochondrial biogenesis genes. We suggest that, at plasmatic concentrations, LD acts as a metabolic disruptor through impaired mitochondrial function and regulation with an impact on cellular energetic metabolism. In addition, we propose that a cellular assay based on the analysis of mitochondria function, such as described here for LD, may be applicable for larger studies on the effects of low concentrations of xenobiotics, because of the exquisite sensitivity of this organelle.

International audience; Context:Focusing on mitochondrial function and thyroid tumorigenesis, we used an integrative approach to identify relevant biomarkers for borderline thyroid lesions.Design:Using cDNA and microRNA (miRNA) microarrays and quantitative RT-PCR analysis (qPCR), we explored samples of various types of thyroid tumors including 25 benign follicular adenomas represented by macrofollicular variants of thyroid adenomas, 38 oncocytic variants of follicular thyroid tumors, 19 papillary thyroid carcinomas, and 10 tumors of uncertain malignant potential, together with 53 normal thyroid tissue samples.Results:Our transcriptomic analysis, which highlighted discrepancies between controls and tumor tissues, as well as between various tumor types, led to the identification of 13 genes, allowing discrimination between the thyroid adenomas, oncocytic variants of follicular thyroid tumors, and papillary thyroid carcinomas, whereas the tumors of uncertain malignant potential were found to overlap these classes. Five of these genes (TP53, HOXA9, RUNX1, MYD88, and CITED1), with a differential expression confirmed by qPCR analysis, are implicated in tumorigenesis, 4 in mitochondrial metabolism (MRPL14, MRPS2, MRPS28, and COX6A1), and 2 in thyroid metabolic pathways (CaMKIINalpha and TPO). The global miRNA analysis revealed 62 differential miRNAs, the expression level for 10 of these being confirmed by qPCR. The differential expression of the miRNAs was in accordance with the modulation of gene expression and the ontologies revealed by our transcriptomic analysis.Conclusions:These findings reinforce the classification of follicular thyroid tumors established by the World Health Organization, and our technique offers a novel molecular approach to refine the classification of thyroid tumors of uncertain malignant potential.

Metabolic modifications of tumor cells are hallmarks of cancer. They exhibit an altered metabolism that allows them to sustain higher proliferation rates in hostile environment outside the cell. In thyroid tumors, the expression of the estrogen-related receptor {alpha} (ERR{alpha}), a major factor of metabolic adaptation, is closely related to the oxidative metabolism and the proliferative status of the cells. To elucidate the role played by ERR{alpha} in the glycolytic adaptation of tumor cells, we focused on the regulation of lactate dehydrogenases A and B (LDHA, LDHB) and the LDHA/LDHB ratio. Our study included tissue samples from 10 classical and 10 oncocytic variants of follicular thyroid tumors and 10 normal thyroid tissues, as well as samples from three human thyroid tumor cell lines: FTC-133, XTC.UC1 and RO82W-1. We identified multiple cis-acting promoter elements for ERR{alpha}, in both the LDHA and LDHB genes. The interaction between ERR{alpha} and LDH promoters was confirmed by chromatin immunoprecipitation assays and in vitro analysis for LDHB. Using knock-in and knock-out cellular models, we found an inverse correlation between ERR{alpha} expression and LDH activity. This suggests that thyroid tumor cells may reprogram their metabolic pathways through the up-regulation of ERR{alpha} by a process distinct from that proposed by the recently revisited Warburg hypothesis.

International audience; Red wine polyphenolic compounds (RWPC) are reported to exert vasculoprotective properties on endothelial cells, involving nitric oxide (NO) release via a redox-sensitive pathway. This NO release involves the activation of the estrogen receptor-alpha (ERα). Paradoxical effects of a RWPC treatment occur in a rat model of post-ischemic neovascularization, where a low-dose is pro-angiogenic while a higher dose is anti-angiogenic. NO and ERα are key regulators of mitochondrial capacity, and angiogenesis is a highly energetic process associated with mitochondrial biogenesis. However, whether RWPC induces changes in mitochondrial capacity has never been addressed. We investigated the effects of RWPC at low (10(-4)g/l, LCP) and high concentration (10(-2)g/l, HCP) in human endothelial cells. Mitochondrial respiration, expression of mitochondrial biogenesis factors and mitochondrial DNA content were assessed using oxygraphy and quantitative PCR respectively. In vitro capillary formation using ECM gel(®) was also performed. Treatment with LCP increased mitochondrial respiration, with a maximal effect achieved at 48h. LCP also increased expression of several mitochondrial biogenesis factors and mitochondrial DNA content. In contrast, HCP did not affect these parameters. Furthermore, LCP modulated both mitochondrial capacity and angiogenesis through mechanisms sensitive to ER, NADPH oxidase and NO-synthase inhibitors. Finally, the inhibition of mitochondrial protein synthesis abolished the pro-angiogenic capacity of LCP. These results suggest a possible association between the modulation of mitochondrial capacity by LCP and its pro-angiogenic activity. These data provide evidence for a role of mitochondria in the regulation of angiogenesis by RWPC.

National audience; Red wine polyphenol (RWPC) extracts has been reported to possess vasoprotective properties that involve nitric oxide (NO) release from endothelial cells via a redox- sensitive pathway. Besides, the molecular target of RWPC to release NO has been recently revealed and it involves the activation of the estrogen receptor alpha (ERα). Paradoxical effects of RWPC have been shown with regard to angiogenesis. Indeed in a rat model of postischemic neovascularization, low- dose is pro- whereas high dose is anti- angiogenic. NO and ERαare key regulators of mitochondrial function. Furthermore, angiogenesis is a highly energetic process associated with mitochondrial biogenesis. However, whether RWPC induces changes in mitochondrial function has never been addressed and it is the aim of this study.The effects of RWPC at low concentration (10- 4 g/l, LCP) and high concentration (10- 2 g/l, HCP) after 48 hours time exposure were investigated on human endothelial cells. Mitochondrial respiration, expression of biogenesis factors and DNA content was assessed using oxygraphy and qRT- PCR, respectively. In vitro capillary formation using Matrigel® was performed. The mechanism involved with respect to ER using the ER- antagonist fulvestrant was studied. The involvement of both NADPH oxidase and NO synthase was addressed using apocynin and L- NA respectively.LCP, but not HCP, increased mitochondrial respiration. The effect of LCP was associated with an increase of both expression of several mitochondrial biogenesis factors (NRF- 1, NRF- 2, ERRα, Tfam, PolG) and mitochondrial DNA content whereas HCP had no effect on these parameters. All the effects of LCP on mitochondrial respiration are prevented by fulvestrant, apocynin and L- NA. LCP also promoted in vitro capillary elongation that was prevented by fulvestrant, apocynin and L- NA. Finally, the inhibition of mitochondrial protein synthesis using chloramphenicol suppressed the pro- angiogenic property of LCP.The present study highlights the implication of the axis ER, NADPH oxidase and NOS pathways on both increase mitochondrial function and capillary elongation in response to RWPC at low concentration. They explain the paradoxical effect of RWPC depending on the concentration with respect to angiogenesis, mitochondria being key targets for its pro- angiogenic properties.

International audience; Members of the peroxisome proliferator-activated receptor γ coactivator-1 family (i.e. PGC-1α, PGC-1β, and the PGC-1-related coactivator (PRC)) are key regulators of mitochondrial biogenesis and function. These regulators serve as mediators between environmental or endogenous signals and the transcriptional machinery governing mitochondrial biogenesis. The FTC-133 and RO82 W-1 follicular thyroid carcinoma cell lines, which present significantly different numbers of mitochondria, metabolic mechanisms, and expression levels of PRC and PGC-1α, may employ retrograde signaling in response to respiratory dysfunction. Nitric oxide (NO) and calcium have been hypothesized to participate in this activity. We investigated the effects of the S-nitroso-N-acetyl-dl-penicillamine-NO donor, on the expression of genes involved in mitochondrial biogenesis and cellular metabolic functions in FTC-133 and RO82 W-1 cells by measuring lactate dehydrogenase and cytochrome c oxidase (COX) activities. We studied the action of ionomycin and 1,2-bis(2-aminophenoxy)ethane-N,N,N′,N′-tetraacetic acid-acetoxymethyl ester (BAPTA/AM) (i.e. a calcium ionophore and a cytosolic calcium chelator) on whole genome expression and mitochondrial biogenesis in RO82 W-1 cells. COX activity and the dynamics of endoplasmic reticulum and mitochondrial networks were analyzed in regard to calcium-modulating treatments. In the FTC-133 and RO82 W-1 cells, the mitochondrial biogenesis induced by NO was mainly related to PRC expression as a retrograde mitochondrial signaling. Ionomycin diminished COX activity and negatively regulated PRC-mediated mitochondrial biogenesis in RO82 W-1 cells, whereas BAPTA/AM produced the opposite effects with a reorganization of the mitochondrial network. This is the first demonstration that NO and calcium regulate mitochondrial biogenesis through the PRC pathway in thyroid cell lines.

Objective To assess the long-term effect on visual development of omega-3 polyunsaturated fatty acid (n-3 PUFA) intake during gestation. Study design Using visual evoked potentials (VEPs), the long-term effects on visual development were evaluated in 136 school-age Inuit children exposed to high levels of n-3 PUFAs during gestation. VEP protocols using color and motion stimuli were used to assess parvocellular and magnocellular responses. Concentrations of the two major n-3 PUFAs (docosahexaenoic acid [DHA] and eicosapentaenoic acid [EPA]) were measured in umbilical cord and child plasma phospholipids, reflecting prenatal and postnatal exposure, respectively. Results After adjustment for confounders, cord plasma DHA level was found to be associated with shorter latencies of the N1 and P1 components of the color VEPs. No effects were found for current n-3 PUFA body burden or motion-onset VEPs. Conclusion This study demonstrates beneficial effects of DHA intake during gestation on visual system function at school age. DHA is particularly important for the early development and long-term function of the visual parvocellular pathway.

Mitochondrial biogenesis, which depends on nuclear as well as mitochondrial genes, occurs in response to increased cellular ATP demand. The nuclear transcriptional factors, estrogen-related receptor alpha (ERRalpha) and nuclear respiratory factors 1 and 2, are associated with the coordination of the transcriptional machinery governing mitochondrial biogenesis, whereas coactivators of the peroxisome proliferator-activated receptor gamma coactivator-1 (PGC-1) family serve as mediators between the environment and this machinery. In the context of proliferating cells, PGC-1-related coactivator (PRC) is a member of the PGC-1 family, which is known to act in partnership with nuclear respiratory factors, but no functional interference between PRC and ERRalpha has been described so far. We explored three thyroid cell lines, FTC-133, XTC.UC1 and RO 82 W-1, each characterized by a different mitochondrial content, and studied their behavior towards PRC and ERRalpha in terms of respiratory efficiency. Overexpression of PRC and ERRalpha led to increased respiratory chain capacity and mitochondrial mass. The inhibition of ERRalpha decreased cell growth and respiratory chain capacity in all three cell lines. However, the inhibition of PRC and ERRalpha produced a greater effect in the oxidative cell model, decreasing the mitochondrial mass and the phosphorylating respiration, whereas the nonphosphorylating respiration remained unchanged. We therefore hypothesize that the ERRalpha-PRC complex plays a role in arresting the cell cycle through the regulation of oxidative phosphorylation in oxidative cells, and through some other pathway in glycolytic cells.

International audience; Background: The human death-associated protein 3 (hDAP3) is a GTP-binding constituent of the small subunit of the mitochondrial ribosome with a pro-apoptotic function.Methods: A search through publicly available microarray data sets showed 337 genes potentially coregulated with the DAP3 gene. The promoter sequences of these 337 genes and 70 out of 85 mitochondrial ribosome genes were analysed in silico with the DAP3 gene promoter sequence. The mitochondrial role of DAP3 was also investigated in the thyroid tumours presenting various mitochondrial contents. Results: The study revealed nine transcription factors presenting enriched motifs for these gene promoters, five of which are implicated in cellular growth (ELK1, ELK4, RUNX1, HOX11-CTF1, TAL1-ternary complex factor 3) and four in mitochondrial biogenesis (nuclear respiratory factor-1 (NRF-1), GABPA, PPARG-RXRA and estrogen-related receptor alpha (ESRRA)). An independent microarray data set showed the overexpression of ELK1, RUNX1 and ESRRA in the thyroid oncocytic tumours. Exploring the thyroid tumours, we found that DAP3 mRNA and protein expression is upregulated in tumours presenting a mitochondrial biogenesis compared with the normal tissue. ELK1 and ESRRA were also showed upregulated with DAP3. Conclusion: ELK1 and ESRRA may be considered as potential regulators of the DAP3 gene expression. DAP3 may participate in mitochondrial maintenance and play a role in the balance between mitochondrial homoeostasis and tumourigenesis.