Mato, J.M. (José María)
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- Methionine adenosyltransferase 1A knockout mice are predisposed to liver injury and exhibit increased expression of genes involved in proliferation(National Academy of Sciences, 2001) Chen, L. (L); Corrales, F.J. (Fernando José); Huang, Z.Z. (Zong-Zhi); Avila, M.A. (Matías Antonio); Lu, S.Z. (S. Z.); An, W.G. (Won G.); Kanel, G. (G.); Mato, J.M. (José María); Álvarez, L. (Lluis)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.
- Impaired liver regeneration in mice lacking methionine adenosyltransferase 1A(Federation of American Society of Experimental Biology, 2004) Corrales, F.J. (Fernando José); Lu, S.C. (Shelly C.); Avila, M.A. (Matías Antonio); Chen, L. (Lixin); Ruiz Garcia-Trevijano, E. (Elena); Lee, T.D. (Taunia D.); Zeng, Y. (Ying); Yang, H. (Heping); Mato, J.M. (José María); French, S.W. (Samuel W.)Methionine adenosyltransferase (MAT) is an essential enzyme because it catalyzes the formation of S-adenosylmethionine (SAMe), the principal biological methyl donor. Of the two genes that encode MAT, MAT1A is mainly expressed in adult liver and MAT2A is expressed in all extrahepatic tissues. Mice lacking MAT1A have reduced hepatic SAMe content and spontaneously develop hepatocellular carcinoma. The current study examined the influence of chronic hepatic SAMe deficiency on liver regeneration. Despite having higher baseline hepatic staining for proliferating cell nuclear antigen, MAT1A knockout mice had impaired liver regeneration after partial hepatectomy (PH) as determined by bromodeoxyuridine incorporation. This can be explained by an inability to up-regulate cyclin D1 after PH in the knockout mice. Upstream signaling pathways involved in cyclin D1 activation include nuclear factor kappaB (NFkappaB), the c-Jun-N-terminal kinase (JNK), extracellular signal-regulated kinases (ERKs), and signal transducer and activator of transcription-3 (STAT-3). At baseline, JNK and ERK are more activated in the knockouts whereas NFkappaB and STAT-3 are similar to wild-type mice. Following PH, early activation of these pathways occurred, but although they remained increased in wild-type mice, c-jun and ERK phosphorylation fell progressively in the knockouts. Hepatic SAMe levels fell progressively following PH in wild-type mice but remained unchanged in the knockouts. In culture, MAT1A knockout hepatocytes have higher baseline DNA synthesis but failed to respond to the mitogenic effect of hepatocyte growth factor. Taken together, our findings define a critical role for SAMe in ERK signaling and cyclin D1 regulation during regeneration and suggest chronic hepatic SAMe depletion results in loss of responsiveness to mitogenic signals.
- S-Adenosylmethionine revisited: its essential role in the regulation of liver function(Elsevier Masson, 2002) Latasa, M.U. (María Ujué); Corrales, F.J. (Fernando José); Perez-Mato, I. (Isabel); Sanchez-del-Pino, M.M. (Manuel M.); Avila, M.A. (Matías Antonio); Ruiz Garcia-Trevijano, E. (Elena); Martinez-Cruz, L.A. (L. Alfonso); Mato, J.M. (José María); Martinez-Chantar, M.L. (María Luz)Dietary methionine is mainly metabolized in the liver where it is converted into S-adenosylmethionine (AdoMet), the main biologic methyl donor. This reaction is catalyzed by methionine adenosyltransferase I/III (MAT I/III), the product of MAT1A gene, which is exclusively expressed in this organ. It was first observed that serum methionine levels were elevated in experimental models of liver damage and in liver cirrhosis in human beings. Results of further studies showed that this pathological alteration was due to reduced MAT1A gene expression and MAT I/III enzyme inactivation associated with liver injury. Synthesis of AdoMet is essential to all cells in the organism, but it is in the liver where most of the methylation reactions take place. The central role played by AdoMet in cellular function, together with the observation that AdoMet administration reduces liver damage caused by different agents and improves survival of alcohol-dependent patients with cirrhosis, led us to propose that alterations in methionine metabolism could play a role in the onset of liver disease and not just be a consequence of it. In the present work, we review the recent findings that support this hypothesis and highlight the mechanisms behind the hepatoprotective role of AdoMet.
- Methionine adenosyltransferase S-nitrosylation is regulated by the basic and acidic amino acids surrounding the target thiol(American Society for Biochemistry and Molecular Biology, 1999) Corrales, F.J. (Fernando José); Perez-Mato, I. (Isabel); Ruiz, F.A. (Félix A.); Castro, C. (Carmen); Mato, J.M. (José María)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 hepatocytes S-nitrosoglutathione monoethyl ester, a cell-permeable nitric oxide donor, markedly reduces cellular S-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 via S-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.
- Hyperhomocysteinemia in liver cirrhosis: mechanisms and role in vascular and hepatic fibrosis(American Heart Association, 2001) Martin-Duce, A. (Antonio); Corrales, F.J. (Fernando José); Berasain, C. (Carmen); Avila, M.A. (Matías Antonio); Rodriguez, J.A. (José Antonio); Ruiz Garcia-Trevijano, E. (Elena); Caballeria, J. (Juan); Mato, J.M. (José María); Arias, R. (Roberto)Numerous clinical and epidemiological studies have identified elevated homocysteine levels in plasma as a risk factor for atherosclerotic vascular disease and thromboembolism. Hyperhomocysteinemia may develop as a consequence of defects in homocysteine-metabolizing genes; nutritional conditions leading to vitamin B(6), B(12), or folate deficiencies; or chronic alcohol consumption. Homocysteine is an intermediate in methionine metabolism, which takes place mainly in the liver. Impaired liver function leads to altered methionine and homocysteine metabolism; however, the molecular basis for such alterations is not completely understood. In addition, the mechanisms behind homocysteine-induced cellular toxicity are not fully defined. In the present work, we have examined the expression of the main enzymes involved in methionine and homocysteine metabolism, along with the plasma levels of methionine and homocysteine, in the liver of 26 cirrhotic patients and 10 control subjects. To gain more insight into the cellular effects of elevated homocysteine levels, we have searched for changes in gene expression induced by this amino acid in cultured human vascular smooth muscle cells. We have observed a marked reduction in the expression of the main genes involved in homocysteine metabolism in liver cirrhosis. In addition, we have identified the tissue inhibitor of metalloproteinases-1 and alpha1(I)procollagen to be upregulated in vascular smooth muscle cells and liver stellate cells exposed to pathological concentrations of homocysteine. Taken together, our observations suggest (1) impaired liver function could be a novel determinant in the development of hyperhomocysteinemia and (2) a role for elevated homocysteine levels in the development of liver fibrosis.
- Proteomic analysis of human hepatoma cells expressing methionine adenosyltransferase I/III Characterization of DDX3X as a target of S-adenosylmethionine(Elsevier, 2012) Corrales, F.J. (Fernando José); Lu, S.C. (Shelly C.); Schröder, P.C. (Paul C.); Fernandez-Irigoyen, J. (Joaquín); Serna, A. (Antonio); Prieto, J. (Jesús); Hernandez-Alcoceba, R. (Rubén); Mato, J.M. (José María); Bigaud, E. (Emilie)Methionine adenosyltransferase I/III (MATI/III) synthesizes S-adenosylmethionine (SAM) in quiescent hepatocytes. Its activity is compromised in most liver diseases including liver cancer. Since SAM is a driver of hepatocytes fate we have studied the effect of re-expressing MAT1A in hepatoma Huh7 cells using proteomics. MAT1A expression leads to SAM levels close to those found in quiescent hepatocytes and induced apoptosis. Normalization of intracellular SAM induced alteration of 128 proteins identified by 2D-DIGE and gel-free methods, accounting for deregulation of central cellular functions including apoptosis, cell proliferation and survival. Human Dead-box protein 3 (DDX3X), a RNA helicase regulating RNA splicing, export, transcription and translation was down-regulated upon MAT1A expression. Our data support the regulation of DDX3X levels by SAM in a concentration and time dependent manner. Consistently, DDX3X arises as a primary target of SAM and a principal intermediate of its antitumoral effect. Based on the parallelism between SAM and DDX3X along the progression of liver disorders, and the results reported here, it is tempting to suggest that reduced SAM in the liver may lead to DDX3X up-regulation contributing to the pathogenic process and that replenishment of SAM might prove to have beneficial effects, at least in part by reducing DDX3X levels. This article is part of a Special Issue entitled: Clinical Proteomics.
- Methionine adenosyltransferase II beta subunit gene expression provides a proliferative advantage in human hepatoma(WB Saunders, 2003) Latasa, M.U. (María Ujué); Martin-Duce, A. (Antonio); Avila, M.A. (Matías Antonio); Ruiz Garcia-Trevijano, E. (Elena); Fortes, P. (Puri); Caballeria, J. (Juan); Mato, J.M. (José María); Martinez-Chantar, M.L. (María Luz)BACKGROUND & AIMS: Of the 2 genes (MAT1A, MAT2A) encoding methionine adenosyltransferase, the enzyme that synthesizes S-adenosylmethionine, MAT1A, is expressed in liver, whereas MAT2A is expressed in extrahepatic tissues. In liver, MAT2A expression associates with growth, dedifferentiation, and cancer. Here, we identified the beta subunit as a regulator of proliferation in human hepatoma cell lines. The beta subunit has been cloned and shown to lower the K(m) of methionine adenosyltransferase II alpha2 (the MAT2A product) for methionine and to render the enzyme more susceptible to S-adenosylmethionine inhibition. METHODS: Methionine adenosyltransferase II alpha2 and beta subunit expression was analyzed in human and rat liver and hepatoma cell lines and their interaction studied in HuH7 cells. beta Subunit expression was up- and down-regulated in human hepatoma cell lines and the effect on DNA synthesis determined. RESULTS: We found that beta subunit is expressed in rat extrahepatic tissues but not in normal liver. In human liver, beta subunit expression associates with cirrhosis and hepatoma. beta Subunit is expressed in most (HepG2, PLC, and Hep3B) but not all (HuH7) hepatoma cell lines. Transfection of beta subunit reduced S-adenosylmethionine content and stimulated DNA synthesis in HuH7 cells, whereas down-regulation of beta subunit expression diminished DNA synthesis in HepG2. The interaction between methionine adenosyltransferase II alpha2 and beta subunit was demonstrated in HuH7 cells. CONCLUSIONS: Our findings indicate that beta subunit associates with cirrhosis and cancer providing a proliferative advantage in hepatoma cells through its interaction with methionine adenosyltransferase II alpha2 and down-regulation of S-adenosylmethionine levels.
- MiR-873-5p acts as an epigenetic regulator in early stages of liver fibrosis and cirrhosis(Springer Nature, 2018) Fernandez, A. (Agustín); Banales, J.M. (Jesús M.); Villa, E. (Erica); Simon, J. (Jorge); Gutiérrez-de-Juan, V. (Virginia); Berasain, C. (Carmen); Arbelaiz, A. (Ander); Zubiete-Franco, I. (Imanol); Lu, S.C. (Shelly C.); Avila, M.A. (Matías Antonio); Aransay, A.M. (Ana M.); Fraga, M.F. (Mario F.); Beraza, N. (Naiara); Perugorria, M.J. (María J.); Lavín, J.L. (José Luis); Crespo, J. (Javier); Iruzibieta, P. (Paula); Varela-Rey, M. (Marta); Delgado, T.C. (Teresa C.); Barbier-Torres, L. (Lucía); Lopitz-Otsoa, F. (Fernando); Fernández-Ramos, D. (David); Anguita, A. (Ángel); Fernández-Tussy, P. (Pablo); Mato, J.M. (José María); Navasa, N. (Nicolás); Martinez-Chantar, M.L. (María Luz)Glycine N-methyltransferase (GNMT) is the most abundant methyltransferase in the liver and a master regulator of the transmethylation flux. GNMT downregulation leads to loss of liver function progressing to fibrosis, cirrhosis, and hepatocellular carcinoma. Moreover, GNMT deficiency aggravates cholestasis-induced fibrogenesis. To date, little is known about the mechanisms underlying downregulation of GNMT levels in hepatic fibrosis and cirrhosis. On this basis, microRNAs are epigenetic regulatory elements that play important roles in liver pathology. In this work, we aim to study the regulation of GNMT by microRNAs during liver fibrosis and cirrhosis. Luciferase assay on the 3ʹUTR-Gnmt was used to confirm in silico analysis showing that GNMT is potentially targeted by the microRNA miR-873-5p. Correlation between GNMT and miR-873-5p in human cholestasis and cirrhosis together with miR-873-5p inhibition in vivo in different mouse models of liver cholestasis and fibrosis [bile duct ligation and Mdr2 (Abcb4)-/- mouse] were then assessed. The analysis of liver tissue from cirrhotic and cholestatic patients, as well as from the animal models, showed that miR-873-5p inversely correlated with the expression of GNMT. Importantly, high circulating miR-873-5p was also detected in cholestastic and cirrhotic patients. Preclinical studies with anti-miR-873-5p treatment in bile duct ligation and Mdr2-/- mice recovered GNMT levels in association with ameliorated inflammation and fibrosis mainly by counteracting hepatocyte apoptosis and cholangiocyte proliferation. In conclusion, miR-873-5p emerges as a novel marker for liver fibrosis, cholestasis, and cirrhosis and therapeutic approaches based on anti-miR-873-5p may be effective treatments for liver fibrosis and cholestatic liver disease.
- Identification of argininosuccinate lyase as a hypoxia-responsive gene in rat hepatocytes(Elsevier, 2000) Latasa, M.U. (María Ujué); Avila, M.A. (Matías Antonio); Carretero, M.V. (M. Victoria); Ruiz Garcia-Trevijano, E. (Elena); Torres, L. (Luis); Mato, J.M. (José María)BACKGROUND/AIMS: The differential oxygenation of periportal and perivenous hepatocytes has been demonstrated as a major determinant in the zonated expression of certain metabolic pathways in the liver. We have searched for novel genes whose expression could be modulated by hypoxia in cultured rat hepatocytes. METHODS: Primary cultures of rat hepatocytes were incubated under normoxic (21% oxygen) or hypoxic (3% oxygen) conditions for 6 h. Differences in gene expression under both conditions were analyzed using the technique of differential display by means of PCR. RESULTS: We have identified the enzyme argininosuccinate lyase (ASL) as being downregulated by hypoxia. ASL is a cytosolic protein which participates in urea metabolism. ASL expression was time-dependently reduced in hypoxia. Hypoxia modulated the responses of this gene to the two main hormonal signals which induce ASL mRNA: glucocorticoids and cAMP. ASL mRNA levels decreased in response to ATP-reducing agents. CoCl2 mimicked the effect of hypoxia, suggesting the implication of a hemoprotein in this response. Hypoxia did not affect ASL mRNA stability, indicating that this effect occurs at the transcriptional level. CONCLUSIONS: Our observations suggest that differences in oxygen levels across the hepatic parenchyma could participate in the zonated expression of ASL.
- Creation of a functional S-nitrosylation site in vitro by single point mutation(Elsevier, 1999) Corrales, F.J. (Fernando José); Perez-Mato, I. (Isabel); Sanchez-del-Pino, M.M. (Manuel M.); Ruiz, F.A. (Félix A.); Kotb, M. (Malak); Castro, C. (Carmen); LeGros, L. (Leighton); Mato, J.M. (José María); Geller, A.M. (Arthur M.)Here we show that in extrahepatic methionine adenosyltransferase replacement of a single amino acid (glycine 120) by cysteine is sufficient to create a functional nitric oxide binding site without affecting the kinetic properties of the enzyme. When wild-type and mutant methionine adenosyltransferase were incubated with S-nitrosoglutathione the activity of the wild-type remained unchanged whereas the activity of the mutant enzyme decreased markedly. The mutant enzyme was found to be S-nitrosylated upon incubation with the nitric oxide donor. Treatment of the S-nitrosylated mutant enzyme with glutathione removed most of the S-nitrosothiol groups and restored the activity to control values. In conclusion, our results suggest that functional S-nitrosylation sites can develop from existing structures without drastic or large-scale amino acid replacements