- Email: [email protected]
P66SHC SIGNALING PATHWAY PLAYS A ROLE IN NONALCOHOLIC STEATOHEPATITIS PROGRESSION IN HUMAN AND MICE
POSTERS SREBP1c mRNA expression was higher in Groups A and C. On the other hand, LDL cholesterol level was significantly higher in Group A than in Group D (Groups A, B, C and D: 8.0±1.7, 7.0±3.4, 6.0±0.0 and 3.0±0.0, respectively). Conclusions: Ovariectomized mice were predisposed to liver steatosis, insulin resistance, and elevated ALT when fed with a high-fat diet, and LPS induced mild hepatic fibrosis and steatosis. These results suggest that the absence of estrogen and the presence LPS contribute to the development of NASH. 1265 P53/P66SHC SIGNALING PATHWAY PLAYS A ROLE IN NONALCOHOLIC STEATOHEPATITIS PROGRESSION IN HUMAN AND MICE K. Tomita1,2 , T. Teratani2 , T. Suzuki2 , H. Yokoyama3 , K. Shimamura2 , K. Nishiyama4 , Y. Okada1 , C. Kurihara1 , H. Ebinuma2 , H. Saito5 , R. Hokari1 , K. Sugiyama2 , K. Hatsuse4 , J. Yamamoto4 , T. Kanai2 , T. Hibi2 , S. Miura1 . 1 Department of Internal Medicine, National Defense Medical College, Saitama, 2 Department of Internal Medicine, 3 Health Center, Keio University School of Medicine, Tokyo, 4 Department of Surgery, National Defense Medical College, Saitama, 5 Graduate School of Pharmaceutical Sciences, Keio University Faculty of Pharmacy, Tokyo, Japan E-mail: [email protected] Background and Aims: As a master sensor of stressful stimuli, the tumor suppressor p53 controls a number of biologic processes, including aging. Hepatic p53 expression is elevated in patients with nonalcoholic steatohepatitis (NASH), the severity of which may reflect the age of the patient. The aim of our study was to examine the roles of p53 in NASH. Methods: Male wild-type and p53-deficient mice were fed a methionine- and choline-deficient diet for eight weeks to induce nutritional steatohepatitis, a model of NASH. Hepatocytes were isolated from p53-deficient mice. The effect of pifithrin-alpha, a p53-inactivating agent, on primary cultured hepatocytes was also examined. Normal liver samples and liver samples from patients with simple steatosis or NASH patients were also evaluated for mRNA expression. Results: p53 deficiency ameliorated the progression of nutritional steatohepatitis. Hepatic p53 and p66Shc signaling along with phosphorylation of p66shc at Ser36 were enhanced in mice NASH model. p53 deficiency suppressed the enhancement of p66Shc signaling, and decreased hepatic lipid peroxidation and apoptotic hepatocytes in NASH. In primary cultured hepatocytes, transforming growth factor (TGF)-beta treatment enhanced p53 and p66Shc signaling, leading to exaggerated reactive oxygen species (ROS) accumulation. Deficiency of p53 signaling reversed TGF-betainduced enhancement of p66Shc signaling and suppressed TGF-beta-induced ROS accumulation in hepatocytes. A lack of p53 signaling also significantly inhibited TGF-beta-induced apoptosis in hepatocytes. Furthermore, the mRNA expression levels of p21 and p66Shc were significantly elevated in human nonalcoholic fatty liver disease (NAFLD) liver samples, in comparison with those in normal liver samples. Among NAFLD patients, the NASH group had significantly higher hepatic expression levels of p21 and p66shc, in comparison to the simple steatosis group. We also found that there was a significant correlation between the gene expression of p21 and p66Shc. Conclusions: p53 signaling in hepatocytes regulates steatohepatitis progression by controlling p66Shc signaling, ROS levels, and apoptosis, in which TGF-beta signaling is implicated. Moreover, p53/p66Shc signaling in the liver appears to be a promising target for the treatment of NASH.
1266 HISTONE VARIANT MACROH2A1 KNOCK-OUT WORSENS HIGH FAT DIET-INDUCED SYSTEMIC INSULIN RESISTANCE, GLUCOSE INTOLERANCE AND HEPATIC STEATOSIS IN MICE D. Koonen1 , V. Pazienza2 , J.R. Pehrson3 , M. Hofker1 , A.G. Ladurner4 , A. Greco5 , C. Podrini5 , M. Vinciguerra5 . 1 Department of Pathology, University Medical Center Groningen, Groningen, The Netherlands; 2 Gastroenterology Unit, IRCCS ’Casa Sollievo della Sofferenza’ Hospital, San Giovanni Rotondo, Italy; 3 Department of Cell and Molecular Biology, University of Pennsylvania, Philadelphia, PA, USA; 4 Department of Physiological Chemistry, Ludwig Maximilians University Munich, Munich, Germany; 5 Institute of Hepatology, Foundation for Liver Research, London, UK E-mail: [email protected] Background and Aims: Hepatic steatosis is a major risk factor for the development of severe liver damage, including fibrosis, cirrhosis and hepatocellular carcinoma. It often exists as a co-morbidity factor with diabetes type I/II and with other manifestations of the metabolic syndrome. Recent studies highlight the importance of an epigenetic basis for the development of steatosis based on macroH2A1. MacroH2A1 is a histone variant of histone H2A, which possesses an additional protein domain called macro. When incorporated into the chromatin of hepatocytes, macroH2A1 regulates gene expression. Two alternatively spliced isoforms of macroH2A1 exist, which have been shown to be markers of breast, skin and lung cancer. Whole-body knock out of macroH2A1 in mice induces glucose intolerance and changes in genes regulating hepatic lipid metabolism. However, overt hepatic steatosis was not observed and the significance of these findings is unclear. We hypothesized that macroH2A1 could be involved in the pathogenesis of hepatic steatosis induced in the high fat-diet mouse model of metabolic syndrome. Methods: Wild type and homozygous knock-out male mice were placed on a high fat diet (Western diet, 42% of energy intake from saturated fats) for 8 weeks. At the end of the treatment, measurement of insulin sensitivity and glucose tolerance (ITT and GTT) were performed. Mice were sacrificed, and plasma and liver tissue harvested for further assays, including protein, gene expression and immunohistochemistry analyses. Results: Deterioration in insulin resistance and glucose intolerance induced by high fat diet was observed in macroH2A1 knockout mice, compared to wild type littermates. Moreover, lack of macroH2A1 in mice significantly worsened the increase in circulating non-esterified fatty acids (NEFA) and the hepatic intracellular content of tryglicerides induced by high fat diet. Gene expression studies unveiled an increase in the hepatic expression of lipoprotein lipase (Lpl) and fatty acid transporter CD36 in knock-out mice. Conclusions: MacroH2A1 is a regulator of hepatic fat accumulation and its absence worsens hepatic steatosis and systemic imbalances upon a high fat regimen in mice. This could be due to a direct effect of macroH2A1 on chromatin structure and on the expression of key genes involved in liver lipid metabolism. 1267 BERBERINE ADMINISTRATION AMELIORATES NECROINFLAMMATION IN EXPERIMENTAL STEATOHEPATITIS INTERFERING WITH THE INFLAMMASOME PATHWAY, BUT IS ASSOCIATED WITH EXTRAHEPATIC TOXICITY E. Vivoli1 , S. Milani1 , A. Provenzano1 , S. Madiai1 , E. Novo2 , M. Parola2 , F. Marra1 . 1 University of Florence, Florence, 2 University of Turin, Turin, Italy E-mail: elisa.vivoli@unifi.it Background/Aims: Berberine (BRB), an alkaloid present in several medicinal plants, possesses antioxidant, anti-inflammatory and immunomodulatory properties. In the liver, BRB exerts inhibitory
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Journal of Hepatology 2012 vol. 56 | S389–S548
1266 HISTONE VARIANT MACROH2A1 KNOCK-OUT WORSENS HIGH FAT DIET-INDUCED SYSTEMIC INSULIN RESISTANCE, GLUCOSE INTOLERANCE AND HEPATIC STEATOSIS IN MICE D. Koonen1 , V. Pazienza2 , J.R. Pehrson3 , M. Hofker1 , A.G. Ladurner4 , A. Greco5 , C. Podrini5 , M. Vinciguerra5 . 1 Department of Pathology, University Medical Center Groningen, Groningen, The Netherlands; 2 Gastroenterology Unit, IRCCS ’Casa Sollievo della Sofferenza’ Hospital, San Giovanni Rotondo, Italy; 3 Department of Cell and Molecular Biology, University of Pennsylvania, Philadelphia, PA, USA; 4 Department of Physiological Chemistry, Ludwig Maximilians University Munich, Munich, Germany; 5 Institute of Hepatology, Foundation for Liver Research, London, UK E-mail: [email protected] Background and Aims: Hepatic steatosis is a major risk factor for the development of severe liver damage, including fibrosis, cirrhosis and hepatocellular carcinoma. It often exists as a co-morbidity factor with diabetes type I/II and with other manifestations of the metabolic syndrome. Recent studies highlight the importance of an epigenetic basis for the development of steatosis based on macroH2A1. MacroH2A1 is a histone variant of histone H2A, which possesses an additional protein domain called macro. When incorporated into the chromatin of hepatocytes, macroH2A1 regulates gene expression. Two alternatively spliced isoforms of macroH2A1 exist, which have been shown to be markers of breast, skin and lung cancer. Whole-body knock out of macroH2A1 in mice induces glucose intolerance and changes in genes regulating hepatic lipid metabolism. However, overt hepatic steatosis was not observed and the significance of these findings is unclear. We hypothesized that macroH2A1 could be involved in the pathogenesis of hepatic steatosis induced in the high fat-diet mouse model of metabolic syndrome. Methods: Wild type and homozygous knock-out male mice were placed on a high fat diet (Western diet, 42% of energy intake from saturated fats) for 8 weeks. At the end of the treatment, measurement of insulin sensitivity and glucose tolerance (ITT and GTT) were performed. Mice were sacrificed, and plasma and liver tissue harvested for further assays, including protein, gene expression and immunohistochemistry analyses. Results: Deterioration in insulin resistance and glucose intolerance induced by high fat diet was observed in macroH2A1 knockout mice, compared to wild type littermates. Moreover, lack of macroH2A1 in mice significantly worsened the increase in circulating non-esterified fatty acids (NEFA) and the hepatic intracellular content of tryglicerides induced by high fat diet. Gene expression studies unveiled an increase in the hepatic expression of lipoprotein lipase (Lpl) and fatty acid transporter CD36 in knock-out mice. Conclusions: MacroH2A1 is a regulator of hepatic fat accumulation and its absence worsens hepatic steatosis and systemic imbalances upon a high fat regimen in mice. This could be due to a direct effect of macroH2A1 on chromatin structure and on the expression of key genes involved in liver lipid metabolism. 1267 BERBERINE ADMINISTRATION AMELIORATES NECROINFLAMMATION IN EXPERIMENTAL STEATOHEPATITIS INTERFERING WITH THE INFLAMMASOME PATHWAY, BUT IS ASSOCIATED WITH EXTRAHEPATIC TOXICITY E. Vivoli1 , S. Milani1 , A. Provenzano1 , S. Madiai1 , E. Novo2 , M. Parola2 , F. Marra1 . 1 University of Florence, Florence, 2 University of Turin, Turin, Italy E-mail: elisa.vivoli@unifi.it Background/Aims: Berberine (BRB), an alkaloid present in several medicinal plants, possesses antioxidant, anti-inflammatory and immunomodulatory properties. In the liver, BRB exerts inhibitory
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Journal of Hepatology 2012 vol. 56 | S389–S548