[Show abstract][Hide abstract] ABSTRACT: The aim of this study is to investigate the protective mechanisms induced by bortezomib added to Institut George Lopez (IGL)-1 preservation solution to protect steatotic livers against cold ischaemia reperfusion injury and to examine whether these mechanisms occur through the activation of adenosine monophosphate activated protein kinase (AMPK), Akt/mTOR pathways.
Steatotic livers from obese rats were preserved for 24 h (at 4°C) in IGL-1 solution with or without bortezomib (100 nM) or pretreated with AMPK inhibitor adenine 9-α-D-arabinofuranoside and preserved in IGL-1 + bortezomib. Livers were then perfused for 2 h at 37°C. Liver injury (alanine aminotransferase/aspartate aminotransferase) and function (bile production and vascular resistance) were measured. Also, Akt/mTOR, phosphorylated AMPK (pAMPK) and apoptosis were determined by Western blot analyses.
Bortezomib addition to IGL-1 solution significantly reduced steatotic liver injury, improved graft function and decreased liver apoptosis. These benefits were diminished by the pretreatment of obese rats with AMPK inhibitor Ara. Western blot analyses showed a significant increase in pAMPK after ischaemia and reperfusion. We also observed a significant phosphorylation of Akt in IGL-1 + bortezomib group that, in turn, induced the phosphorylation of mTOR and glycogen synthase kinase 3β.
Bortezomib, at low and non toxic concentration, is a promising additive to IGL-1 solution for steatotic liver preservation. Its protective effect is due to the activation of AMPK and Akt/mTOR pathways.
The Journal of pharmacy and pharmacology. 10/2013;
[Show abstract][Hide abstract] ABSTRACT: BACKGROUND: The dramatic shortage of organs leads to consider the steatotic livers for transplantation although their poor tolerance against ischemia reperfusion injury (IRI). Ubiquitin proteasome system (UPS) inhibition during hypothermia prolongs myocardial graft preservation. The role of UPS in the liver IRI is not fully understood. Bortezomib (BRZ) treatment at non-toxic doses of rats fed alcohol chronically has shown protective effects by increasing liver antioxidant enzymes. We evaluated and compared both proteasome inhibitors BRZ and MG132 in addition to University of Wisconsin preservation solution (UW) at low and non toxic dose for fatty liver graft protection against cold IRI. EXPERIMENTAL: Steatotic and non-steatotic livers have been stored in UW enriched with BRZ (100nM) or MG132 (25μM), for 24hours at 4°C and then subjected to 2hour-normothermic reperfusion (37°C). Liver injury (AST/ALT), hepatic function (bile output; vascular resistance), mitochondrial damage (GLDH), oxidative stress (MDA), nitric oxide (NO) (e-NOS activity; nitrates/nitrites), proteasome chymotrypsin-like activity (ChT), and UPS (19S and 20S5 beta) protein levels have been measured. RESULTS: ChT was inhibited when BRZ and MG132 were added to UW. Both inhibitors prevented liver injury (AST/ALT), when compared to UW alone. BRZ increased bile production more efficiently than MG132. Only BRZ decreased vascular resistance in fatty livers, which correlated with an increase in NO generation (through e-NOS activation) and AMPK phosphorylation. GLDH and MDA were also prevented by BRZ. In addition, BRZ inhibited adiponectin, IL-1, and TNF alpha, only in steatotic livers. CONCLUSION: MG132 and BRZ, administrated at low and non toxic doses, are very efficient to protect fatty liver grafts against cold IRI. The benefits of BRZ are more effective than those of MG132. This evidenced for the first time the potential use of UPS inhibitors for the preservation of marginal liver grafts and for future applications in the prevention of IRI.
Experimental and Molecular Pathology 01/2013; · 2.13 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Corneal epithelium regeneration using autologous oral mucosal epithelial cell sheet is a successful new approach in corneal therapy. In the present study, gene expression profiling was performed to characterize engineered cell sheets. Cell sheets were obtained by culturing isolated rabbit oral mucosal epithelial cells on a thermoresponsive cultureware (UpCell®, CellSeed Inc. Japan). H&E staining of cell sheets showed a multistratified epithelium, similar to corneal epithelium. DeltaN-p63 stained positive in the basal cells, indicating that cell sheets have renewal capacity. Microarray analysis of these cell sheets showed that only 160 genes out of 43,000 rabbit probes listed on the microarray chip were identified. We first identified the extracellular matrix group of genes and found that matrix metalloproteinase MMP-1, MMP-3 and MMP-12, known to promote angiogenesis, were down regulated, while MMP-13 and collagen type VIII alpha 1 (COL8A1), proteins involved in wound healing, were up regulated. Tissue inhibitors of metalloproteinase TIMP-1 and TIMP-3, anti-angiogenic factors, were also identified. Gap junction protein A7 (GJA7 or Connexin 45) was found up regulated, indicating that cell sheets have developed well preserved cell-cell interactions. Alcohol dehydrogenase 5 (ADH class III) and aldehyde dehydrogenase (ALDH1A1), involved in protecting the cornea against oxidative stress induced by UV radiation, were also found up regulated. In conclusion, microarray analysis has led us to identify new target molecules and their subsequent biochemical analysis indicated how the composite cell sheets are advantageous to the original isolated cells in terms of the integrity and potency of corneal epithelial grafts without any scaffolds.
Fetal ovine model for in-situ esophagus tissue engineering. 01/2013; 10(6). · 3.16 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Mallory-Denk bodies (MDBs) are aggresomes composed of undigested ubiqutinated short lived proteins which have accumulated because of a decrease in the rate of their degradation by the 26s proteasome. The decrease in the activity of the proteasome is due to a shift in the activity of the 26s proteasome to the immunoproteasome triggered by an increase in expression of the catalytic subunits of the immunoproteasome which replaces the catalytic subunits of the 26s proteasome. This switch in the type of proteasome in liver cells is triggered by the binding of IFNγ to the IFNγ sequence response element (ISRE) located on the FAT10 promoter. To determine if either FAT10 or IFNγ are essential for the formation of MDBs we fed both IFNγ and FAT10 knock out (KO) mice DDC added to the control diet for 10weeks in order to induce MDBs. Mice fed the control diet and Wild type mice fed the DDC or control diet were compared. MDBs were located by immunofluorescent double stains using antibodies to ubiquitin to stain MDBs and FAT10 to localize the increased expression of FAT10 in MDB forming hepatocytes. We found that MDB formation occurred in the IFNγ KO mice but not in the FAT10 KO mice. Western blots showed an increase in the ubiquitin smears and decreases β 5 (chymotrypsin-like 26S proteasome subunit) in the Wild type mice fed DDC but not in the FAT10 KO mice fed DDC. To conclude, we have demonstrated that FAT10 is essential to the induction of MDB formation in the DDC fed mice.
Experimental and Molecular Pathology 09/2012; · 2.13 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Ischemia/reperfusion injury (IRI), inherent in liver transplantation (LT), is the main cause of initial deficiencies and primary non-function of liver allografts. Living-related LT was developed to alleviate the mortality resulting from the scarcity of suitable deceased grafts. The main problem in using living-related LT for adults is graft size disparity. In this study we propose for the first time that the use of a proteasome inhibitor (Bortezomib) treatment could improve liver regeneration and reduce IRI after Reduced-Size Orthotopic Liver transplantation (ROLT). Rat liver grafts were reduced by removing the left lateral lobe and the two caudate lobes and preserved in UW or IGL-1 preservation solution for 1h liver and then subjected to ROLT with or without Bortezomib treatment. Our results show that Bortezomib reduces IRI after LT and is correlated with a reduction in mitochondrial damage, oxidative stress and endoplasmic reticulum stress. Furthermore, Bortezomib also increased liver regeneration after reduced-size LT and increased the expression of well-known ischemia/reperfusion protective proteins such as nitric oxide synthase, heme oxigenase 1 (HO-1) and Heat Shock Protein 70. Our results open new possibilities for the study of alternative therapeutic strategies aimed at reducing IRI and increasing liver regeneration after LT. It is hoped that the results of our study will contribute towards improving the understanding of the molecular processes involved in IRI and liver regeneration, and therefore help to improve the outcome of this type of LT in the future.
Experimental and Molecular Pathology 03/2012; 93(1):99-110. · 2.13 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: EZH2/H3K27me3 and polycomb group complex (PcG) play a major role in regulating global gene expression including tumor suppressor genes. EZH2 is linked to cell cycle regulated EZH2 phosphorylation by CDK1, a mitotic kinase which increases in arrested mitosis compared to S phase. CDK1 phosphorylation of EZH2 accelerates the degradation of pEZH2. Phospho-EZH2 is subjected to ubiquitination. The half-like of pEZH2 is shorter when compared to total EZH2. In the present study, pEZH2 was found concentrated together with ubiquitin in the Mallory-Denk bodies (MDB) that were formed in hepatocytes in the livers of drug primed mice refed DDC and humans with alcoholic hepatitis or hepatocellular carcinoma. The cells that formed MDBs in the mice livers studied were associated with a growth advantage and a high proliferative index. However, the livers from patients with alcoholic hepatitis showed evidence of cell cycle arrest where PCNA, cyclin D1 and p27 positive nuclei were numerous but Ki-67 positive nuclei were scarce. It is concluded that MDB formation is linked to the cell cycle and global gene expression (i.e. loss of gene silencing) through its association with the regulation of the polycomb group PRC2/EZH2/H3K27me3 complex.
Experimental and Molecular Pathology 03/2012; 92(3):318-26. · 2.13 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: In the present study, the beneficial effects of proteasome inhibitor treatment in reducing ethanol-induced steatosis were investigated. A microarray analysis was performed on the liver of rats injected with PS-341 (Bortezomib, Velcade), and the results showed that proteasome inhibitor treatment significantly reduced the mRNA expression of SREBP-1c, and the downstream lipogenic enzymes, such as fatty acid synthase (FAS) and acetyl-CoA carboxylase (ACC), which catalyzes the carboxylation of acetyl-CoA to malonyl-CoA, the rate-limiting step in fatty acid synthesis. ELOVL6, which is responsible for fatty acids long chain elongation, was also significantly downregulated by proteasome inhibitor treatment. Moreover, PS-341 administration significantly reduced the expression of acyl-glycerol-3-phosphate acyltransferase (AGPAT), and diacylglycerol acyltransferase (DGAT), enzyme involved in triacylglycerol (TAG) synthesis. Finally, PS-341 was found to downregulate the enzyme 3-hydroxy-3-methylglutaryl-CoenzymeA synthase (HMG-CoA synthase) that is responsible for cholesterol synthesis. Proteasome inhibitor was also found to play a role in intestinal lipid adsorption because apolipoproteins A (apoA-I, apoAII, apoA-IV and ApoCIII) were downregulated by proteasome inhibitor treatment, especially ApoA-II that is known to be a marker of alcohol consumption. Proteasome inhibitor treatment also decreased apobec-1 complementation factor (ACF) leading to lower level of editing and production of ApoB protein. Moreover apolipoprotein C-III, a major component of chylomicrons was significantly downregulated. However, lipoprotein lipase (Lpl) and High density lipoprotein binding protein (Hdlbp) mRNA levels were increased by proteasome inhibitor treatment. These results suggested that proteasome inhibitor treatment could be used to reduce the alcohol-enhanced lipogenesis and alcohol-induced liver steatosis. A morphologic analysis, performed on the liver of rats fed ethanol for one month and treated with PS-341, showed that proteasome inhibitor treatment significantly decreased ethanol-induced liver steatosis. SREBP-1c, FAS and ACC were increased by ethanol feeding alone, but were significantly decreased when proteasome inhibitor was administered to rats fed ethanol. Our results also show that both mRNA and protein levels of these lipogenic enzymes, up regulated by ethanol, were then downregulated when proteasome inhibitor was administered to rats fed ethanol. It was also confirmed that alcohol feeding caused an increase in AGPAT and DGAT, which was prevented by proteasome inhibitor treatment of the animal fed ethanol. Chronic alcohol feeding did not affect the gene expression of HMG-CoA synthase. However, PS341 administration significantly reduced the HMG-CoA synthase mRNA levels, confirming the results obtained with the microarray analysis. C/EBP transcription factors alpha (CCAAT/enhancer-binding protein alpha) has been shown to positively regulate SREBP-1c mRNA expression, thus regulating lipogenesis. Proteasome inhibition caused a decrease in C/EBP alpha mRNA expression, indicating that C/EBP downregulation may be the mechanism by which proteasome inhibitor treatment reduced lipogenesis. In conclusion, our results indicate that proteasome activity is not only involved in downregulating fatty acid synthesis and triacylglycerol synthesis, but also cholesterol synthesis and intestinal lipid adsorption. Proteasome inhibitor, administrated at a non-toxic low dose, played a beneficial role in reducing lipogenesis caused by chronic ethanol feeding and these beneficial effects are obtained because of the specificity and reversibility of the proteasome inhibitor used.
Experimental and Molecular Pathology 03/2012; 93(1):26-34. · 2.13 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: In recent years, methyl one-carbon metabolism has received a great deal of attention because the disruption of methyl balance in a variety of genetically modified mice is associated with the development of various forms of liver injury, namely fatty liver disease and hepatocellular carcinoma (HCC). In addition, patients with liver disease often have an abnormal expression of key genes involved in methionine metabolism as well as elevated serum levels of methionine and homocysteine (Hcy). S-adenosylmethionine (SAMe) has rapidly moved from being a methyl donor to a key metabolite that regulates hepatocyte proliferation, necrosis and differentiation. Biosynthesis of SAMe occurs in all mammalian cells as the first step in methionine catabolism in a reaction catalyzed by methionine adenosyltransferase (MAT). Decreased hepatic SAMe biosynthesis is a consequence of numerous forms of chronic liver injury. In an animal model of chronic liver SAMe deficiency, the liver is predisposed to further injury and develops spontaneous steatohepatitis and HCC. SAMe treatment in experimental animal models of liver injury shows hepatoprotective properties. Meta-analyses also showed that it is effective in the treatment of patients with cholestatic liver diseases. We studied the survival of liver cells treated with SAMe and betaine using Hepa 1-6 and E47/C34 cell lines. We showed that exogenous SAMe decreased the number of Hepa 1-6 and E47/C34 cells, and increased the number of dead cells in vitro. Betaine had no significant effect on the number of surviving cells and the number of dead cells. The combination of both methyl donors significantly increased the survival of liver cells and reduced necrosis, compared to SAMe alone. This study showed the inhibition of the proliferation and increased necrosis in response to SAMe on liver cancer cell lines Hepa 1-6 and C34.
Experimental and Molecular Pathology 02/2012; 92(1):126-30. · 2.13 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Mallory-Denk body (MDB) formation is a component of alcoholic and non alcoholic hepatitis. Proteins of the TLR pathway were shown to be involved in the formation of MDBs, in mice fed DDC. TLR genes are upregulated and SAMe supplementation prevents this up regulation and prevented the formation of MDBs. DNA of livers from control mice, from mice fed DDC 10weeks, refed 1week with DDC and with DDC+SAMe were extracted and used to study the methylation pattern of genes involves in the TLR pathway. A PCR array was used to analyze it. Using PCR arrays for the mouse TLR pathway,24 genes were found whose expression of IL12A was regulated by the methylation of its gene. DDC fed for 10weeks reduced the methylation of the IL12A gene expression. This expression was also reduced when DDC was refed. However, when SAMe was fed, the intermediate level methylation of IL12A was up regulated to the intermediate level and the methylation of the promoter decreased compared to DDC refeeding or DDC 10weeks. IL12A is known to induce the production of IFNg by NK and L(T). We showed in a previous publication that IFNg is one of the major cytokines involved in the induction of MDB formation. The low expression of IL12A associated with the intermediate methylation of its promoter could explain one step in the mechanism which leads to the formation of MDBs.
Experimental and Molecular Pathology 01/2012; 92(2):191-3. · 2.13 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Innate immunity factors such as conversion of the 26S proteasome to form the immunoproteasome and the Toll-like receptor signaling pathways are activated in chronic hepatitis induced by the carcinogenic drug DDC. Over time, preneoplastic hepatocyte phenotypes appear in the liver parenchyma. These changed hepatocytes expand in number because they have a growth advantage over normal hepatocytes when responding to chronic liver injury. The changed hepatocytes can be identified using immunofluorescent antibodies to preneoplastic cells e.g. FAT10/UbD, A2 macroglobulin, glutathione transpeptidase, alpha fetoprotein, glycipan 3, FAS, and gamma glutamyl transpeptidase. The formation of the preneoplastic cells occurs concomitant with activation of the Toll-like receptor signaling pathways and the transformation of the 26S proteasome to form the immunoproteasome. This transformation is in response to interferon stimulating response element on the promoter of the FAT10/UbD gene. NFκB, Erk, p38 and Jnk are also up regulated. Specific inhibitors block these responses in vitro in a mouse tumor cell line exposed to interferon gamma. Mallory-Denk bodies form in these preneoplastic cells, because of the depletion of the 26S proteasome due to formation of the immunoproteasome. Thus, MDB forming cells are also markers of the preneoplastic hepatocytes. The UbD positive preneoplastic cells regress when the liver injury induced chronic hepatitis subsides. When the drug DDC is refed to mice and chronic hepatitis is activated, the preneoplastic cell population expands and Mallory-Denk bodies rapidly reform. This response is remembered by the preneoplastic cells for at least four months indicating that an epigenetic cellular memory has formed in the preneoplastic cells. This proliferative response is prevented by feeding methyl donors such as S-adenosylmethionine or betaine. Drug feeding reduces the methylation of H(3) K4, 9, and 27 and this response is prevented by feeding the methyl donors. After 8 to 15months of drug withdrawal in mice the preneoplastic liver cells persist as single or small clusters of cells in the liver lobules. Multiple liver tumors form, some of which are hepatocellular carcinomas. The tumors immunostain positively for the same preneoplastic markers as the preneoplastic cells. Similar cells are identified in human cirrhosis and hepatocellular carcinoma indicating the relevance of the drug model described here to the preneoplastic changes associated with human chronic hepatitis and hepatocellular carcinoma.
Experimental and Molecular Pathology 07/2011; 91(3):653-9. · 2.13 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Blood alcohol levels (BAL) cycle up and down over a 7-8 day period when ethanol is fed continuously for one month in the intragastric tube feeding rat model (ITFRM) of alcoholic liver disease. The cycling phenomenon is due to an alternating increase and decrease in the metabolic rate. Recently, we found that S-adenosyl-methionine (SAMe) fed with alcohol prevented the BAL cycle.
Using the ITFRM we fed rats betaine (2 g/kg/day) with ethanol for 1 month and recorded the daily 24 h urine ethanol level (UAL) to measure the BAL cycle. UAL is equivalent to BAL because of the constant ethanol infusion. Liver histology, steatosis and BAL were measured terminally after 1 month of treatment. Microarray analysis was done on the mRNA extracted from the liver to determine the effects of betaine and alcohol on changes in gene expression.
Betaine fed with ethanol completely prevented the BAL cycle similar to SAMe. Betaine also significantly reduced the BAL compared to ethanol fed rats without betaine. This was also observed when SAMe was fed with ethanol. The mechanism involved in both cases is that SAMe is required for the conversion of epinephrine from norepinephrine by phenylethanolamine methyltransferase (PNMT). Epinephrine is 5 to 10 fold more potent than norepinephrine in increasing the metabolic rate. The increase in the metabolic rate generates NAD, permitting ADH to increase the oxidation of alcohol. NAD is the rate limiting factor in oxidation of alcohol by alcohol dehydrogenase (ADH). This explains how SAMe and betaine prevented the cycle. Microarray analysis showed that betaine feeding prevented the up regulation of a large number of genes including TLR2/4, Il-1b, Jax3, Sirt3, Fas, Ifngr1, Tgfgr2, Tnfrsf21, Lbp and Stat 3 which could explain how betaine prevented fatty liver.
Betaine feeding lowers the BAL and prevents the BAL cycle by increasing the metabolic rate. This increases the rate of ethanol elimination by generating NAD.
Experimental and Molecular Pathology 06/2011; 91(2):540-7. · 2.13 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: There is a need for a nontoxic antioxidant agent to be identified which will prevent alcoholic liver disease (ALD) in alcoholic patients. We tested 4 candidate agents: quercetin, EGCG, catechin and betaine, all of which occur naturally in food. HepG2 cells overexpressing CYP2E1 were subjected to arachidonic acid, iron and 100mM ethanol with or without the antioxidant agent. All the agents prevented oxidative stress and MDA/4HNE formation induced by ethanol, except for EGCG. Catechin prevented CYP2E1 induction by ethanol. All the agents tended to down-regulate the ethanol-induced increased expression of glutathionine peroxidase 4 (GPX4). All the agents, except catechin, tended to reduce the expression of SOD2 induced by ethanol. Heat shock protein 70 was up-regulated by ethanol alone and betaine tended to prevent this. All 4 agents down-regulated the expression of Gadd45b in the presence of ethanol, which could explain the mechanism of DNA demethylation associated with the up-regulation of the gene expression observed in experimental ALD. In conclusion, the in vitro model of oxidative stress induced by ethanol provided evidence that all 4 agents tested prevented some aspect of liver cell injury caused by ethanol.
Experimental and Molecular Pathology 02/2011; 90(3):295-9. · 2.13 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Recently it has been shown that the expression of the immunoproteasome increased in proportion to the degree of chronic inflammation in both the liver cell cytoplasm and nuclei in liver biopsies from patients who had chronic active hepatitis or cirrhosis. In the present study, biopsies from patients with steatohepatitis, with or without Mallory-Denk body (MDB) formation, were studied by immunofluorescent staining. Normal liver showed colocalization of FAT10, LMP2, LMP7, and MECL-1 at the mitochondria. Only LMP2 and LMP7 were found in the cell nuclei. Liver biopsies from patients with steatohepatitis and MDB formation, and a case of hepatocellular carcinoma forming MDBs in the tumor cells, showed colocalization of FAT10 and ubiquitin with LMP2, LMP7 and MECL-1 within the MDB. This indicates involvement of the immunoproteasome in MDB formation in steatohepatitis cases and in a case of HCC forming MDBs. Prior studies have shown that the immunoproteasome was involved in drug-induced MDB formation using the same immunofluorescent colocalization approach as was used on these human liver biopsies. The increase in the immunoproteasome subunit proteins was made at the expense of the 26S proteasome. This indicates that the shift from the 26S to the immunoproteasome had occurred in the MDB positive hepatocytes.
Experimental and Molecular Pathology 01/2011; 90(3):252-6. · 2.13 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Toll-like receptors (TLR) play a role in mediating the proinflammatory response, fibrogenesis and carcinogenesis in chronic liver diseases such as alcoholic liver disease, non-alcoholic liver disease, hepatitis C and hepatocellular carcinoma. This is true in experimental models of these diseases. For this reason, we investigated the TLR proinflammatory response in the chronic intragastric tube feeding rat model of alcohol liver disease. The methyl donor S-adenosylmethionine was also fed to prevent the gene expression changes induced by ethanol. Ethanol feeding tended to increase the up regulation of the gene expression of TLR2 and TLR4. SAMe feeding prevented this. TLR4 and MyD88 protein levels were significantly increased by ethanol and this was prevented by SAMe. This is the first report where ethanol feeding induced TLR2 and SAMe prevented the induction by ethanol. CD34, FOS, interferon responsive factor 1 (IRF-1), Jun, TLR 1,2,3,4,6 and 7 and Traf-6 were found to be up regulated as seen by microarray analysis where rats were sacrificed at high blood alcohol levels compared to pair fed controls. Il-6, IL-10 and IFNγ were also up regulated by high blood levels of ethanol. The gene expression of CD14, MyD88 and TNFR1SF1 were not up regulated by ethanol but were down regulated by SAMe. The gene expression of IL-1R1 and IRF1 tended to be up regulated by ethanol and this was prevented by feeding SAMe. The results suggest that SAMe, fed chronically prevents the activation of TLR pathways caused by ethanol. In this way the proinflammatory response, fibrogenesis, cirrhosis and hepatocellular carcinoma formation due to alcohol liver disease could be prevented by SAMe.
Experimental and Molecular Pathology 01/2011; 90(3):239-43. · 2.13 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Betaine, a methyl donor active in methionine metabolism, is effective in preventing and reversing experimental alcohol liver disease. The metabolic and molecular biologic mechanisms involved in this prevention are only partially known. To further investigate how betaine modifies the effects of ethanol on the liver, rats were given an acute ethanol bolus with or without betaine and the results were compared to isocaloric dextrose-fed controls. Livers were subjected to microarray analysis, and functional pathways and individual gene expression changes were analyzed. Experimental groups were compared by Venn diagrams showing that both ethanol and betaine caused a change in the expression of a large number of genes indicating that the changes were global. The bio-informatic analysis showed that all the KEGG functional pathways were affected and mainly down regulated at 3 h post bolus when ethanol plus betaine were compared with ethanol-fed rats. The most profound effect of betaine was on the metabolic pathways both at 3 and 12 h post bolus. At 3 h, the changes in gene expression were mostly down regulated, but at 12 h, the changes were regulated equally up and down. This hypothesis-driven analysis showed that the effects of betaine on the effects of ethanol were partly transient.
[Show abstract][Hide abstract] ABSTRACT: An alcohol bolus causes the blood alcohol level (BAL) to peak at 1-2 h post ingestion. The ethanol elimination rate is regulated by alcohol metabolizing enzymes, primarily alcohol dehydrogenase (ADH1), acetaldehyde dehydrogenase (ALDH), and cytochrome P450 (CYP2E1). Recently, S-adenosylmethionine (SAMe) was found to reduce acute BALs 3 h after an alcohol bolus. The question, then, was: what is the mechanism involved in this reduction of BAL by feeding SAMe? To answer this question, we investigated the changes in ethanol metabolizing enzymes and the epigenetic changes that regulate the expression of these enzymes during acute binge drinking and chronic drinking.
Rats were fed a bolus of ethanol with or without SAMe, and were sacrificed at 3 h or 12 h after the bolus.
RT-PCR and Western blot analyses showed that SAMe significantly induced ADH1 levels in the 3 h liver samples. However, SAMe did not affect the changes in ADH1 protein levels 12 h post bolus. Since SAMe is a methyl donor, it was postulated that the ADH1 gene expression up regulation at 3 h was due to a histone modification induced by methylation from methyl transferases. Dimethylated histone 3 lysine 4 (H3K4me2), a modification responsible for gene expression activation, was found to be significantly increased by SAMe at 3 h post bolus.
These results correlated with the low BAL found at 3 h post bolus, and support the concept that SAMe increased the gene expression to increase the elimination rate of ethanol in binge drinking by increasing H3K4me2.
Experimental and Molecular Pathology 12/2010; 89(3):217-21. · 2.13 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Oxidative stress occurs in the liver of rats fed with alcohol chronically due to ethanol metabolism by CYP2E1, causing liver injury. The proteasome is considered as an antioxidant defense in the cell because of its activity in removing damaged and oxidized proteins, but a growing body of evidence shows that proteasome inhibitor treatment, at a non toxic low dose, provides protection against oxidative stress. In the present study, rats were fed with ethanol for 4 weeks and were treated with the proteasome inhibitor PS-341 (Bortezomib, Velcade®). Exposure to proteasome inhibitor elicited the elevation of antioxidative defense by enhancing the levels of mRNA and protein expression transcripts of glutathione reductase (GSR), glutathione synthetase (GSS), glutathione peroxidase 2 (GPX2), and superoxide dismutase 2 (SOD2) in the liver of rats fed with ethanol chronically, while ethanol alone did not increase these genes' mRNA. Our results also showed that glutamate cysteine ligase catalytic subunit (GCLC), a rate-limiting enzyme in glutathione biosynthesis, was also up regulated in the liver of rats fed with ethanol and injected with PS-431. Nrf2 mRNA level was significantly decreased in the liver of ethanol fed rats, as well as in the livers of animal fed with ethanol and treated with proteasome inhibitor, indicating that the mechanism by which proteasome inhibitor up regulates the antioxidant response element is not due to regulation of Nrf2. However, ATF4, a major regulator of antioxidant response elements, was significantly up regulated by proteasome inhibitor treatment. The beneficial effects of proteasome inhibitor treatment also reside in the reversibility of the drug because the proteasome activity was significantly increased 72 h post treatment. In conclusion, proteasome inhibitor treatment used at a non toxic low dose has potential protective effects against oxidative stress due to chronic ethanol feeding.
Experimental and Molecular Pathology 10/2010; 90(1):123-30. · 2.13 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Mice fed DDC (0.1%) for 10 weeks, and then withdrawn from the drug for 1 month, retain the ability to form Mallory-Denk bodies (MDBs) when the drug is refed for 7 days. The number of liver cells that form MDBs increased and partially replaced normal liver cells, at the end of 7 days of refeeding DDC. The MDBs that formed were associated with increased expression of UbD (also called FAT10) in the Mallory-Denk body forming cells. UbD is over expressed in 70% of human HCCs, but its cellular localization is not well established. UbD belongs to the UbL family (ubiquitin-like), and can be linked to others proteins with their 2 C-terminal glycine to lysine. By Western Blot, UbD was found to be covalently linked with proteins. We performed immunohistochemistry on tissue from mouse liver and found that UbD was located in the cytoplasm and in one or two nuclei of the same hepatocyte. However, in primary cell culture, UbD formed speckles within the cytoplasm of the liver cell. A similar pattern of cytoplasmic localization was observed in the Hepa 1-6 cell lines, which over expressed UbD fused with GFP at the C-Terminal. The localization and the control of UbD localization remain unclear. The identification of proteins that interact with UbD and the post translational modification of UbD would help to determine the regulation of this localization and function.
Experimental and Molecular Pathology 10/2010; 89(2):103-8. · 2.13 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: The overexpression of FAT10 is characteristic of numerous types of carcinoma including liver, gastric and colon carcinomas. In the case of colon carcinoma it is possible to determine the point in the progression from the benign to the malignant process of colon cancer development by determining which stage in the neoplastic process FAT10 overexpression occurs. This stage was determined by measuring the intensity of fluorescence of immunohistochemically stained normal mucosa, tubular adenomas, hyperplastic polyps, serrated adenomas, villotubular, villous adenomas and invasive adenocarcinoma stages. Using this approach it was found that the overexpression of FAT10 began at the serrated adenoma stage and continued to include the villous and villotubular stages and the invasive adenocarcinoma stage. The FAT10 overexpression by invasive adenocarcinoma was accompanied by the expression of the catalytic subunits of the immunoproteasome which is functionally tied to the overexpression of FAT10, Toll-like receptor activation and the proinflammatory response.
Experimental and Molecular Pathology 09/2010; 90(1):51-4. · 2.13 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: This editorial reviews the recent evidence showing that Mallory-Denk bodies (MDBs) form in hepatocytes as the result of a drug-induced shift from the 26s proteasome formation to the immunoproteasome formation. The shift is the result of changes in gene expression induced in promoter activation, which is induced by the IFNγ and TNFα signaling pathway. This activates TLR 2 and 4 receptors. The TLR signaling pathway stimulates both the induction of a cytokine proinflammatory response and an up regulation of growth factors. The MDB- forming hepatocytes proliferate as a result of the increase in growth factor expression by the MDB- forming cells, which selectively proliferate in response to drug toxicity. All of these mechanisms are induced by drug toxicity, and are prevented by feeding the methyl donors SAMe and betaine, supporting the epigenetic response of MDB formation.
World journal of hepatology. 08/2010; 2(8):295-301.