Fernando J. Corrales

Methionine adenosyltransferase 1A knockout mice are predisposed to liver injury and exhibit increased expression of genes involved in proliferation

Liver-specific and nonliver-specific methionine adenosyltransferases (MATs) are products of two genes, MAT1A and MAT2A, respectively, that catalyze the formation of S-adenosylmethionine (AdoMet), the principal biological methyl donor. Mature liver expresses MAT1A, whereas MAT2A is expressed in extrahepatic tissues and is induced during liver growth and dedifferentiation. To examine the influence of MAT1A on hepatic growth, we studied the effects of a targeted disruption of the murine MAT1A gene. MAT1A mRNA and protein levels were absent in homozygous knockout mice. At 3 months, plasma methionine level increased 776% in knockouts. Hepatic AdoMet and glutathione levels were reduced by 74 and 40%, respectively, whereas S-adenosylhomocysteine, methylthioadenosine, and global DNA methylation were unchanged. The body weight of 3-month-old knockout mice was unchanged from wild-type littermates, but the liver weight was increased 40%. The Affymetrix genechip system and Northern and Western blot analyses were used to analyze differential expression of genes. The expression of many acute phase-response and inflammatory markers, including orosomucoid, amyloid, metallothionein, Fas antigen, and growth-related genes, including early growth response 1 and proliferating cell nuclear antigen, is increased in the knockout animal. At 3 months, knockout mice are more susceptible to choline-deficient diet-induced fatty liver. At 8 months, knockout mice developed spontaneous macrovesicular steatosis and predominantly periportal mononuclear cell infiltration. Thus, absence of MAT1A resulted in a liver that is more susceptible to injury, expresses markers of an acute phase response, and displays increased proliferation.

S-Adenosylmethionine: a control switch that regulates liver function

Genome sequence analysis reveals that all organisms synthesize S‐adenosylmethionine (AdoMet) and that a large fraction of all genes is AdoMet‐dependent methyltransferases. AdoMet‐dependent methylation has been shown to be central to many biological processes. Up to 85% of all methylation reactions and as much as 48% of methionine metabo‐lism occur in the liver, which indicates the crucial importance of this organ in the regulation of blood methionine. Of the two mammalian genes (MAT1A, MAT2A) that encode methionine adenosyltransferase (MAT, the enzyme that makes AdoMet), MAT1A is specifically expressed in adult liver. It now appears that growth factors, cytokines, and hormones regulate liver MAT mRNA levels and enzyme activity and that AdoMet should not be viewed only as an intermediate metabolite in methionine catabolism, but also as an intracellular control switch that regulates essential he‐patic functions such as regeneration, differentiation, and the sensitivity of this organ to injury. The aim of this review is to integrate these recent findings linking AdoMet with liver growth, differentiation, and injury into a comprehensive model. With the availability of AdoMet as a nutritional supplement and evidence of its beneficial role in various liver diseases, this review offers insight into its mechanism of action.—Mato, J. M., Corrales, F. J., Lu, S. C., Avila, M. A. S‐Adenosylmethionine: a control switch that regulates liver function. FASEB J. 16, 15–26 (2002)

Selective glutathione depletion of mitochondria by ethanol sensitizes hepatocytes to tumor necrosis factor

BACKGROUND & AIMS Tumor necrosis factor (TNF)-alpha induces cell injury by generating oxidative stress from mitochondria. The purpose of this study was to determine the effect of ethanol on the sensitization of hepatocytes to TNF-alpha. METHODS Cultured hepatocytes from ethanol-fed (ethanol hepatocytes) or pair-fed (control hepatocytes) rats were exposed to TNF-alpha, and the extent of oxidative stress, gene expression, and viability were evaluated. RESULTS Ethanol hepatocytes, which develop a selective deficiency of mitochondrial glutathione (mGSH), showed marked susceptibility to TNF-alpha. The susceptibility to TNF-alpha, manifested as necrosis rather than apoptosis, was accompanied by a progressive increase in hydrogen peroxide that correlated inversely with cell survival. Nuclear factor kappaB activation by TNF-alpha was significantly greater in ethanol hepatocytes than in control hepatocytes, an effect paralleled by the expression of cytokine-induced neutrophil chemoattractant. Similar sensitization of normal hepatocytes to TNF-alpha was obtained by depleting the mitochondrial pool of GSH with 3-hydroxyl-4-pentenoate. Restoration of mGSH by S-adenosyl-L-methionine or by GSH-ethyl ester prevented the increased susceptibility of ethanol hepatocytes to TNF-alpha. CONCLUSIONS These results indicate that mGSH controls the fate of hepatocytes in response to TNF-alpha. Its depletion caused by alcohol consumption amplifies the power of TNF-alpha to generate reactive oxygen species, compromising mitochondrial and cellular functions that culminate in cell death.

Reduced mRNA abundance of the main enzymes involved in methionine metabolism in human liver cirrhosis and hepatocellular carcinoma

Abstract Background/Aims: It has been known for at least 50 years that alterations in methionine metabolism occur in human liver cirrhosis. However, the molecular basis of this alteration is not completely understood. In order to gain more insight into the mechanisms behind this condition, mRNA levels of methionine adenosyltransferase ( MAT1A ), glycine methyltransferase ( GNMT ), methionine synthase ( MS ), betaine homocysteine methyltransferase ( BHMT ) and cystathionine β-synthase ( CBS ) were examined in 26 cirrhotic livers, five hepatocellular carcinoma (HCC) tissues and ten control livers. Methods: The expression of the above-mentioned genes was determined by quantitative RT-PCR analysis. Methylation of MAT1A promoter was assessed by methylation-sensitive restriction enzyme digestion of genomic DNA. Results: When compared to normal livers MAT1A , GNMT, BHMT, CBS and MS mRNA contents were significantly reduced in liver cirrhosis. Interestingly, MAT1A promoter was hypermethylated in the cirrhotic liver. HCC tissues also showed decreased mRNA levels of these enzymes. Conclusions: These findings establish that the abundance of the mRNA of the main genes involved in methionine metabolism is markedly reduced in human cirrhosis and HCC. Hypermethylation of MAT1A promoter could participate in its reduced expression in cirrhosis. These observations help to explain the hypermethioninemia, hyperhomocysteinemia and reduced hepatic glutathione content observed in cirrhosis.

Spontaneous oxidative stress and liver tumors in mice lacking methionine adenosyltransferase 1A

In mammals, methionine metabolism occurs mainly in the liver via methionine adenosyltransferase‐catalyzed conversion to S‐adenosylmethionine. Of the two genes that encode methionine adenosyltransferase(MAT1A and MAT2A), MAT1A is mainly expressed in adult liver whereas MAT2A is expressed in all extrahepatic tissues. Mice lacking MAT1A have reduced hepatic S‐adenosylmethionine content and hyperplasia and spontaneously develop nonalcoholic steatohepatitis. In this study, we examined whether chronic hepatic Sadenosylmethionine deficiency generates oxidative stress and predisposes to injury and malignant transformation. Differential gene expression in MAT1A knockout mice was analyzed following the criteria of the Gene Ontology Consortium. Susceptibility of MAT1A knockout mice to CCl4‐induced hepatotoxicity and malignant transformation was determined in 3‐ and 18month‐old mice, respectively. Analysis of gene expression profiles revealed an abnormal expression of genes involved in the metabolism of lipids and carbohydrates in MAT1A knockout mice, a situation that is reminiscent of that found in diabetes, obesity, and other conditions associated with nonalcoholic steatohepatitis. This aberrant expression of metabolic genes in the knockout mice was associated with hyperglycemia, increased hepatic CYP2E1 and UCP2 expression and triglyceride levels, and reduced hepatic glutathione content. The knockout animals have increased lipid peroxidation and enhanced sensitivity to CCl4‐induced liver damage, which was largely due to increased CYP2E1 expression because diallyl sulfide, an inhibitor of CYP2E1, prevented CCl4‐induced liver injury. Hepatocellular carcinoma developed in more than half of the knockout mice by 18 months of age. Taken together, our findings define a critical role for S‐adenosylmethionine in maintaining normal hepatic function and tumorigenesis of the liver.

Correlation between Gene Expression and GO Semantic Similarity

This research analyzes some aspects of the relationship between gene expression, gene function, and gene annotation. Many recent studies are implicitly based on the assumption that gene products that are biologically and functionally related would maintain this similarity both in their expression profiles as well as in their Gene Ontology (GO) annotation. We analyze how accurate this assumption proves to be using real publicly available data. We also aim to validate a measure of semantic similarity for GO annotation. We use the Pearson correlation coefficient and its absolute value as a measure of similarity between expression profiles of gene products. We explore a number of semantic similarity measures (Resnik, Jiang, and Lin) and compute the similarity between gene products annotated using the GO. Finally, we compute correlation coefficients to compare gene expression similarity against GO semantic similarity. Our results suggest that the Resnik similarity measure outperforms the others and seems better suited for use in Gene Ontology. We also deduce that there seems to be correlation between semantic similarity in the GO annotation and gene expression for the three GO ontologies. We show that this correlation is negligible up to a certain semantic similarity value; then, for higher similarity values, the relationship trend becomes almost linear. These results can be used to augment the knowledge provided by clustering algorithms and in the development of bioinformatic tools for finding and characterizing gene products.

Functional proteomics of nonalcoholic steatohepatitis: Mitochondrial proteins as targets of S-adenosylmethionine

Recent work shows that S-adenosylmethionine (AdoMet) helps maintain normal liver function as chronic hepatic deficiency results in spontaneous development of steatohepatitis and hepatocellular carcinoma. The mechanisms by which these nontraditional functions of AdoMet occur are unknown. Here, we use knockout mice deficient in hepatic AdoMet synthesis (MAT1A−/−) to study the proteome of the liver during the development of steatohepatitis. One hundred and seventeen protein spots, differentially expressed during the development of steatohepatitis, were selected and identified by peptide mass fingerprinting. Among them, 12 proteins were found to be affected from birth, when MAT1A−/− expression is switched on in WT mouse liver, to the rise of histological lesions, which occurs at ≈8 months. Of the 12 proteins, 4 [prohibitin 1 (PHB1), cytochrome c oxidase I and II, and ATPase β-subunit] have known roles in mitochondrial function. We show that the alteration in expression of PHB1 correlates with a loss of mitochondrial function. Experiments in isolated rat hepatocytes indicate that AdoMet regulates PHB1 content, thus suggesting ways by which steatohepatitis may be induced. Importantly, we found the expression of these mitochondrial proteins was abnormal in ob/ob mice and obese patients who are at risk for nonalcoholic steatohepatitis.

Methionine adenosyltransferase S-nitrosylation is regulated by the basic and acidic amino acids surrounding the target thiol

S-Adenosylmethionine serves as the methyl donor for many biological methylation reactions and provides the propylamine group for the synthesis of polyamines.S-Adenosylmethionine is synthesized from methionine and ATP by the enzyme methionine adenosyltransferase. The cellular factors regulating S-adenosylmethionine synthesis have not been well defined. Here we show that in rat hepatocytesS-nitrosoglutathione monoethyl ester, a cell-permeable nitric oxide donor, markedly reduces cellularS-adenosylmethionine content via inactivation of methionine adenosyltransferase by S-nitrosylation. Removal of the nitric oxide donor from the incubation medium leads to the denitrosylation and reactivation of methionine adenosyltransferase and to the rapid recovery of cellular S-adenosylmethionine levels. Nitric oxide inactivates methionine adenosyltransferase viaS-nitrosylation of cysteine 121. Replacement of the acidic (aspartate 355) or basic (arginine 357 and arginine 363) amino acids located in the vicinity of cysteine 121 by serine leads to a marked reduction in the ability of nitric oxide to S-nitrosylate and inactivate hepatic methionine adenosyltransferase. These results indicate that protein S-nitrosylation is regulated by the basic and acidic amino acids surrounding the target cysteine.

Modulation of rat liver S-adenosylmethionine synthetase activity by glutathione

Resumen del poster presentado al 50th Inner Ear Biology Workshop, celebrado en Alcala de Henares-Madrid (Espana) del 10 al 13 de septiembre de 2013.Resumen del trabajo presentado al 15o Congreso Nacional de la Sociedad Espanola de Neurociencia (SENC) celebrado en Oviedo del 25 al 27 de septiembre de 2013.Resumen del poster presentado al CIBERDEM Annual Meeting, celebrado en Cerdanyola del Valles, Barcelona (Espana) del 11 al 13 de mayo de 2016.-- et al.Resumen del trabajo presentado al XXXVIII Congreso de la Sociedad Espanola de Ciencias Fisiologicas (SECF), celebrado en Zaragoza del 13 al 16 de septiembre de 2016.Poster presentado en el XI European Meeting on Glial Cells in Health and Disease, celebrado los dias 3 al 6 de julio de 2013 en Berlin (Alemania)Memoria presentada para optar al grado de Doctor por la Licenciada en Biologia Angela Prieto Folgado y realizada en el Instituto de Investigaciones Biomedicas Alberto Sols.La realizacion de este trabajo ha sido posible gracias a la financiacion otorgada por el FIS al proyecto de investigacion 96/1803.Grant Funding Source: Supported by the Fondo de Investigaciones Sanitarias (PI0011406) to MF.The chemotherapeutic study of a limited series of steroidal sapogenins from several endemic species of the flora of the Canary Islands is presented here. On the whole, they possess a very weak antibacterial activity, a slight antifungal effect and one of them, vespertilin, displays interesting cytostatic activity (ID50 = 5 micrograms/ml). A pharmacodynamic screening carried out on this product mainly revealed very slight toxicity, antihistaminic activity and a light tranquilizing effect. The data obtained justify further research.The purpose of this study was to characterize the role of ions other than Ca2+ in hepatic responses to alpha 1-adrenergic stimulation. We report that the alpha 1-adrenoreceptor activation of hepatic functions is accompanied by extracellular acidification and an increase in intracellular pH. These effects are dependent on extracellular Na+ concentration and are inhibited by the Na+/H+ antiporter blocker 5-(N-ethyl-N-isopropyl) amiloride under conditions that preclude antagonistic effects on agonist binding. Thus, the activation of plasma membrane Na+/H+ exchange is an essential feature of the hepatic alpha-adrenoreceptor-coupled signaling pathway. The following observations indicate that the sustained hepatic alpha 1-adrenergic actions rely on a functional coupling between the plasma membrane Na+/H+ and Na+/Ca2+ exchangers, resulting in the stimulation of Ca2+ influx. 1) Inhibition of the Na+/K(+)-ATPase does not prevent the alpha 1-adrenergic effects. However, alpha 1-adrenoreceptor stimulation fails to induce intracellular alkalinization and to acidify the extracellular medium in the absence of extracellular Ca2+. 2) A non-receptor-induced increase in intracellular Na+ concentration, caused by the ionophore monensin, stimulates Ca2+ influx and increases vascular resistance. 3) Inhibition of Na+/Ca2+ exchange prevents, in a concentration-dependent manner, most of the alpha 1-agonist-induced responses. 4) The actions of Ca(2+)-mobilizing vasoactive peptide receptors or alpha 2-adrenoreceptors, which produce neither sustained extracellular acidification nor release of Ca2+, are insensitive to Na+/H+ exchange blockers.Poster presentado en la VII Reunion Anual de la Red Tematica de Investigacion Cooperativa en Cancer (RTICC), celebrada en Salamanca el 24 de septiembre de 2014Resumen del trabajo presentado al VI Meeting de la Red Espanola de Canales Ioniocs (RECI), celebrado en Santiago de Compostela del 6 al 8 de septiembre de 2017.Tesis Doctoral presentada por Laura Jimenez Perez para optar al grado de doctor por la Universidad de Valladolid, Departamento de Bioquimica y Biologia Molecular y FisiologiaPoster presentado en la VII Reunion Anual de la Red Tematica de Investigacion Cooperativa en Cancer (RTICC), celebrada en Salamanca el 24 de septiembre de 2014Resumen del trabajo presentado al XXXXVIII Congreso de la Sociedad Espanola de Bioquimica y Biologia Molecular (SEBBM), celebrado en Valencia del 7 al 10 de septiembre de 2015.Esta Tesis Doctoral fue realizada en el Centro Andaluz de Biologia del Desarrollo por la licenciada Briseida Beli Cacho Valadez para optar al grado de Doctor por la Universidad Pablo de Olavide.Rat liver S-adenosylmethionine (AdoMet) synthetase appears as high-M(r) (tetramer) and low-M(r) (dimer) forms. Both are inhibited in the presence of GSSG at pH 8. The calculated Ki values are 2.14 and 4.03 mM for the high- and low-M(r) forms, respectively. No effect on enzyme activity was observed in the presence of GSH, but modulation of inhibition by GSSG can be obtained by addition of GSH. At a total glutathione concentration (GSH + GSSG) of 10 mM, a KOX of 1.74 was calculated for the high-M(r) form, whereas this constant was 2.85 for the low-M(r) AdoMet synthetase. No incorporation of [35S]GSSG was observed in either of the enzyme forms, and inhibition of enzyme activity was correlated with dissociation of both AdoMet synthetases to a monomer. The data obtained in the presence of GSSG seem to suggest that oxidation leads to the formation of an intrasubunit disulfide. The possible regulation of AdoMet synthetase activity by the GSH/GSSG ratio is discussed, as well as its in vivo significance.Trabajo presentado en el XI Simposi de Neurobiologia: Future technical advances, organizado por la Socitat Catalana de Biologia, en Barcelona, los dias 12 y 13 de noviembre de 2018El estudio de la relacion entre componentes de la dieta y la salud/enfermedad utiliza metodos de valoracion de la ingesta dietetica, del estatus nutricional y de marcadores de funcion o de efecto. En concreto, en el estudio de los carotenoides y la salud ocular, interesa el estudio de dos carotenoides sin actividad provitamina A, la luteina y la zeaxantina, por su posible papel en la optimizacion de la funcion visual y en la prevencion de enfermedades cronicas asociadas a la edad, y de tres carotenoides con actividad provitamina A: -caroteno, -caroteno y -criptoxantina, por ser precursores de retinol, nutriente del que depende el ciclo visual para una vision normal. En el presente trabajo se ha llevado a cabo el estudio de los carotenoides de la dieta mas relevantes para la salud ocular humana considerando de forma simultanea parametros relacionados con la ingesta, el estatus y la funcion visual, asi como diversas variables que pueden modificar el estatus nutricional, como son la concentracion de lipidos en sangre, y la bioaccesibilidad de los carotenoides a partir de alimentos de amplio consumo...Fetal rat hepatocytes treated with transforming growth factor beta (TGF-beta) die by apoptosis. However, a subpopulation of them survives and undergoes an epithelial mesenchymal transition (EMT). This transition also occurs upon incubation with fetal bovine serum. We have isolated the subpopulations that undergo EMT (TGF-beta-treated-fetal hepatocytes: TbetaT-FH; serum-treated-fetal hepatocytes: ST-FH) and show that they present high levels of vimentin and Snail expression and lack cytokeratin 18 and E-cadherin. Both TbetaT-FH and ST-FH cells require mitogens to grow and maintain the response to TGF-beta in terms of growth inhibition. However, they lack differentiation markers such as the liver-enriched transcription factors hepatocyte nuclear factor 4 (HNF-4) or HNF-1alpha and express the progenitor marker OV-6. Interestingly, the EMT process confers them resistance to the apoptotic effect of TGF-beta, with cells showing higher levels of active AKT and Bcl-x(L) than fetal hepatocytes. In summary, these cells are refractory to the apoptotic effects of TGF-beta, showing characteristics of liver progenitors and of some hepatocellular carcinoma cells.Memoria de tesis presentada por Luis Vazquez Fonseca, Licenciado en Bioquimica para optar al grado de Doctor. Esta Tesis Doctoral ha sido realizada bajo el programa de doctorado de Biotecnologia y Tecnologia Quimica en el grupo de investigacion del CIBERER U729 en el Centro Andaluz de Biologia del Desarrollo, Area de Biologia Celular del Departamento de Fisiologia, Anatomia y Biologia Celular de la Universidad Pablo de Olavide y bajo la direccion del Dr. Carlos Santos Ocana y el Dr. Placido NavasResumen del poster presentado al Joint FEPS & XXXVI Spanish Physiological Society Congress (Sociedad Espanola de Ciencias Fisiologicas) celebrado en Santiago de Compostela (Espana) del 8 al 11 de septiembre de 2012.Poster presentado al 17o Congreso Nacional de la Sociedad Espanola de Neurociencia, celebrado en Alicante del 27 al 30 de septiembre de 2017.The mutations at the bithorax locus produce a transformation of anterior haltere into anterior wing. The bx1 allele presents unusual features when compared with other bx alleles. The phenotype of bx1 homozygotes is temperature sensitive but only with regard to the distal and not to the proximal transformation, thus suggesting two different components in the bithorax transformation. The phenotype of bx1 homozygotes is stronger than that of bx1 over the deletion of the gene, suggesting a trans interaction of the bx1 chromosomes which results in mutual partial inactivation. We show by temperature shift and clonal analysis experiments that the decision on whether to differentiate haltere or wing structures is taken at the end of the proliferation period of the mutant disc.Poster presentado al XXXVII Congreso de la Sociedad Espanola de Bioquimica y Biologia Molecular, celebrado en Granada del 9 al 12 de septiembre de 2014.Poster presentado al XXVII Congreso Nacional de la Asociacion Espanola de Genetica Humana celebrado en Madrid del 10 al 12 de abril de 2013.Poster presentado al XXXVII Congreso de la Sociedad Espanola de Bioquimica y Biologia Molecular, celebrado en Granada del 9 al 12 de septiembre de 2014.Poster presentado en el XI European Meeting on Glial Cells in Health and Disease, celebrado los dias 3 al 6 de julio de 2013 en Berlin (Alemania)Resumen del trabajo presentado al Spanish Society of Biochemistry and Molecular Biology (SEBBM), celebrado en Madrid del 16 al 19 de julio de 2019.Poster presentado en el XII European Meeting on Glial Cells in Health and Disease, celebrado los dias 15 a 18 de julio de 2015 en Bilbao (Espana)Trabajo presentado en el XL Congreso de la Sociedad Espanola de Bioquimica y Biologia Molecular. FEBS3+1st Joint Meeting of the French-Portuguese-Spanish Biochemical and Molecular, celebrado en Barcelona (Espana), del 23 al 26 de octubre de 2017Resumen del poster presentado al Joint FEPS & XXXVI Spanish Physiological Society Congress (Sociedad Espanola de Ciencias Fisiologicas) celebrado en Santiago de Compostela (Espana) del 8 al 11 de septiembre de 2012.Trabajo presentado en el XII GEIRLI Meeting: New trends in redox biology: a multidisciplinary approach, celebrado en Barcelona (Espana), los dias 4 y 5 de julio de 2019Treatment of nucleosomal particles with dimethylmaleic anhydride, a reagent for protein amino groups, is accompanied by a biphasic release of histones H2A plus H2B; one H2A.H2B dimer is more easily released than the other. This behavior allows the preparation of nucleosomal particles containing only one H2A.H2B dimer, which were complemented with 125I-labeled H2A.H2B. These reconstituted particles, which contain one labeled and one unlabeled H2A.H2B dimer, were treated with the amount of reagent needed to release one of the two H2A.H2B dimers. Radioactivity was equally distributed between residual particles and released proteins, which is consistent with equivalent binding sites in the nucleosomal particle for H2A.H2B dimers, rather than with intrinsically different sites. The asymmetric release of H2A.H2B dimers would be caused by a change in the binding site of one dimer following the release of the other. This behavior might be related to the structural dynamics of nucleosomes.Resumen del trabajo presentado al European Society of Cardiology (ESC) Congress, celebrado en Barcelona (Espana) del 26 al 30 de agosto de 2017.Resumen del poster presentado al 49th European Association for the Study of Diabetes Annual Meeting, celebrado en Barcelona (Espana) del 23 al 27 de septiembre de 2013.-- et al.Trabajo doctoral realizado por Da Rebeca Lapresa Ruiz de Gauna, para optar al grado de doctor por la Universidad de Salamanca.Rationale: Several animal models have been developed to study acute lung injury (ALI); however the majority of these studies are focused on different mechanisms within the acute phase. These models do not allow studying the mechanisms in the later phases or testing any possible long-term treatment. The aim of this study was to develop an experimental ALI model simulating bronchial aspiration of gastric contents with bacterial superinfection with alveolar epithelial damage persisting over time. Methods: Sprague-Dawley rats (200-250g) were anesthetized with isofluorane. ALI was induced by intratracheal instillation of HCl (1 µl/g, 0.1 mol/L pH=1.4) followed by instillation of LPS from Escherichia coli O55:B5 (0, 10, 20, 30 or 40µg/g b.w.) two hours later. Control rats were treated with intratracheal instillations of saline. After 72h, the animals were sacrificed and bronchoalveolar lavage fluid (BALF) was sampled for further analysis of total protein concentration by bicinchoninic acid method. Results: At 72 h, rats suffered a significant loss of weight proportional to the administered dose of LPS (5.6% with 10µg/g b.w, 12.6% with 20µg/g b.w, 14.2% with 30µg/g b.w and 17.7% with 40µg/g b.w). Control rats gained in weight at 72h. LPS at 10, 20, 30 and 40µg/g b.w induced a 1.7, 2.5, 2.9 and 3.4 fold increase in total protein concentration in BAL fluid, respectively, reflecting a substantial increase proportional to the LPS dose. Conclusion: The degree of weight loss and the increase of total protein concentration in BAL fluid in the current model may reflect disease severity and progression. This model would be useful in future for new therapeutical options. Grant acknowledgements: FIS-PI12/02548 and Fundacio Parc Tauli.Resumen del trabajo presentado al European Respiratory Society (ERS) International Congress, celebrado en Paris (Francia) del 15 al 19 de septiembre de 2018.Resumen del trabajo presentado a las 5as Jornadas de Formacion del CIBERES celebradas en Bunyola (Mallorca) del 18 al 19 de octubre de 2012.Resumen del poster presentado al Joint FEPS & XXXVI Spanish Physiological Society Congress (Sociedad Espanola de Ciencias Fisiologicas) celebrado en Santiago de Compostela (Espana) del 8 al 11 de septiembre de 2012.Resumen del trabajo presentado al XIII Congreso de la Sociedad Espanola del Dolor, celebrado en Pamplona del 2 al 4 de junio de 2016.This work was supported by grants FIS-01/1048 and FIS-02/1199 from the Fondo de Investigacion Sanitaria and grant SA-087/01 from Junta de Castilla y Leon.Resumen del poster presentado al Joint Meeting of the American Physiological Society and the Physiological Society, celebrado en Dublin (Irlanda) del 29 al 31 de julio de 2016.Trabajo presentado al 5th International Conference on Phospholipase A2 Mediated Signaling in Translational Medicine celebrado en New Orleans (US) del 20 al 21 de mayo de 2013.Tesis Doctoral presentada por Rebeca Torres Merino para optar al grado de Doctora por la Universidad de Valladolid, Facultad de Medicina: Dpto. de Bioquimica y Biologia Molecular y Fisiologia.Poster presentado al Annual Meeting of the Association for Research in Vision and Ophthalmology (ARVO), celebrado en Seattle, Washington (US) del 1 al 5 de mayo de 2016.Resumen del trabajo presentado al 63rd Annual Meeting Biophysical Society, celebrado en Baltimore, Maryland (USA) del 2 al 6 de marzo de 2019.Poster presentado al XXXVII Congreso de la Sociedad Espanola de Bioquimica y Biologia Molecular, celebrado en Granada del 9 al 12 de septiembre de 2014.Resumen del poster presentado a la 5th Conference on Advances in Molecular Mechanisms Underlying Neurological Disorders (Joint conference of the European Society for Neurochemistry and the Biochemical Society) en la University of Bath (UK) del 23 al 26 de junio de 2013.-- Tambien presentado al 15o Congreso Nacional de la Sociedad Espanola de Neurociencia (SENC) celebrado en Oviedo del 25 al 27 de septiembre de 2013.Resumen del trabajo presentado al XXXVI Congreso de la Sociedad Espanola de Bioquimica y Biologia Molecular celebrado en Madrid del 4 al 6 de septiembre de 2013.Resumen del trabajo presentado a la 5th Conference on Advances in Molecular Mechanisms Underlying Neurological Disorders (Joint conference of the European Society for Neurochemistry and the Biochemical Society) en la University of Bath (UK) del 23 al 26 de junio de 2013.Resumen del poster presentado al XXVIII Congreso Nacional de la Sociedad Espanola de diabetes, celebrado en Bilbao del 20 al 22 de abril de 2016.SAF2016-77703-C2-2-R of the Ministerio de Economia y Competitividad, Spain and the European Regional Development Fund (ERDF); AGAUR 2017-SGR106 and the CERCA Programme of the Generalitat de Catalunya; C. Sanfeliu belong to Group 05 of CIBER Epidemiologia y Salud Publica (CIBERESP) of the Instituto de Salud Carlos III, Ministerio de Sanidad y Consumo, Spain

Interaction of liver methionine adenosyltransferase with hydroxyl radical.

Liver methionine adenosyltransferase (MAT) plays a critical role in the metabolism of methionine converting this amino acid, in the presence of ATP, into S‐adenosylmethionine. Here we report that hydrogen peroxide (H2O2), via generation of hydroxyl radical, inactivates liver MAT by reversibly and covalently oxidizing an enzyme site. In vitro studies using pure liver recombinant enzyme and mutants of MAT, where each of the 10 cysteine residues of the enzyme subunit were individually changed to serine by site‐directed mutagenesis, identified cysteine 121 as the site of molecular interaction between H2O2 and liver MAT. Cysteine 121 is specific to the hepatic enzyme and is localized at a “flexible loop” over the active site cleft of MAT. In vivo studies, using wild‐type Chinese hamster ovary (CHO) cells and CHO cells stably expressing liver MAT, demonstrate that the inactivation of MAT by H2O2 is specific to the hepatic enzyme, resulting from the modification of the cysteine residue 121, and that this effect is mediated by the generation of the hydroxyl radical. Our results suggest that H2O2‐induced MAT inactivation might be the cause of reduced MAT activity and abnormal methionine metabolism observed in patients with alcoholic liver disease.—Sánchez‐Góngora, E., Ruiz, F., Mingorance, J., An, W., Corrales, F. J., and Mato, J. M. Interaction of liver methionine adenosyltransferase with hydroxyl radical. FASEB J. 11, 1013–1019 (1997)