Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound

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Query: EC:2.6.1.2 (alanine aminotransferase)
26,722 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

We have previously demonstrated that after bile duct ligation hepatocytes express Bcl-2, although the mechanisms regulating Bcl-2 expression were not identified. Our aim was to determine if biliary constituents induce hepatocellular expression of Bcl-2 by a cyclooxygenase-2 (COX-2)-dependent mechanism. We used the choledocho-venous fistula (CVF) rat model for these studies and inhibited COX-2 by feeding the animals nimesulide, a selective inhibitor of COX-2 activity. Serum bile acids were 70-fold greater in CVF animals compared with controls, although liver histology and serum alanine aminotransferase values remained normal for the duration of the study. Neither Bcl-2 nor COX-2 was detected in sham-operated animals. However, Bcl-2 was expressed in hepatocytes but not in other liver cells in the CVF animals. In contrast, COX-2 protein was identified in Kupffer cells but not in hepatocytes of CVF animals. Hepatic Bcl-2 protein expression was fourfold lower in the livers from nimesulide-treated CVF rats. In conclusion, high circulating concentrations of biliary constituents are associated with stimulation of de novo hepatocyte expression of Bcl-2 and Kupffer cell expression of COX-2. These data suggest Kupffer cell-derived prostanoids may regulate Bcl-2 expression in the hepatocyte.
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PMID:Kupffer cell-derived cyclooxygenase-2 regulates hepatocyte Bcl-2 expression in choledocho-venous fistula rats. 1129 87

Ischemia-reperfusion injury is responsible for the morbidity associated with liver surgery under total vascular exclusion or after liver transplantation. Recently, it has been reported that mitochondrial K(ATP) channel openers have an effect on myocardial protection via a pharmacological preconditioning action. However, it remains unclear as to whether K(ATP) channel openers can reduce ischemia-reperfusion injury in the liver. The aim of this study was to determine the effects of the mitochondrial K(ATP) channel opener, nicorandil, on ischemia-reperfusion injury in the rat liver. Male Wistar rats were subjected to 73% ischemia for 45 minutes followed by 120 minutes of reperfusion. Nicorandil (3 mg/kg) was orally administered 60 minutes before hepatic ischemia. Nicorandil significantly decreased plasma levels of alanine aminotransferase and lactate dehydrogenase by about 50% and inhibited the remarkably increased TUNEL-positive hepatocytes after reperfusion. Some mediators associated with apoptosis were analyzed by Western blotting. Cytochrome-c and caspase-3 levels in the cytosol increased after reperfusion; nicorandil inhibited the release of cytochrome-c and activation of caspase-3. The expression of Bax and Bcl-2 was significantly increased after reperfusion, being slightly inhibited by the administration of nicorandil. These results suggest that the protective effects of nicorandil against hepatic ischemia-reperfusion injury correlate with the inhibition of mitochondrial cytochrome-c release and caspase-3 activation. These findings demonstrate that nicorandil may become a therapeutic drug for ischemia reperfusion-related liver injury.
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PMID:Mitochondrial K(ATP) channel opener prevents ischemia-reperfusion injury in rat liver. 1580 66

P-selectin glycoprotein ligand-1 (PSGL-1) mediates the initial tethering of leukocytes to activated platelets and endothelium. We report molecular cloning and characterization of the rat PSGL-1 gene. A neutralizing Ab was generated, and its binding epitope was mapped to the N-terminal binding region of rat PSGL-1. We examined the effects of early PSGL-1 blockade in rat liver models of cold ischemia, followed by ex vivo reperfusion or transplantation (orthotopic liver transplantation (OLT)) using an anti-PSGL-1 Ab with diminished Fc-mediated effector function. In the ex vivo hepatic cold ischemia and reperfusion model, pretreatment with anti-PSGL-1 Ab improved portal venous flow, increased bile production, and decreased hepatocellular damage. Rat pretreatment with anti-PSGL-1 Ab prevented hepatic insult in a model of cold ischemia, followed by OLT, as assessed by 1) decreased hepatocellular damage (serum glutamic oxaloacetic transaminase/glutamic-pyruvic transaminase levels), and ameliorated histological features of ischemia/reperfusion injury, consistent with extended OLT survival; 2) reduced intrahepatic leukocyte infiltration, as evidenced by decreased expression of P-selectin, ED-1, CD3, and OX-62 cells; 3) inhibited expression of proinflammatory cytokine genes (TNF-alpha, IL-1beta, IL-6, IFN-gamma, and IL-2); and 4) prevented hepatic apoptosis accompanied by up-regulation of antiapoptotic Bcl-2/Bcl-xL protective genes. Thus, targeting PSGL-1 with a blocking Ab that has diminished Fc-mediated effector function is a simple and effective strategy that provides the rationale for novel therapeutic approaches to maximize the organ donor pool through the safer use of liver transplants despite prolonged periods of cold ischemia.
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PMID:Molecular characterization of rat leukocyte P-selectin glycoprotein ligand-1 and effect of its blockade: protection from ischemia-reperfusion injury in liver transplantation. 1636 57

Although IL-10 down-regulates pro-inflammatory cytokine secretion by hepatic Kupffer cells, the mechanisms underlying its hepatoprotective effects are not fully clear. This study tested the hypothesis that IL-10 protects the liver against pro-inflammatory cytokines by counteracting their pro-apoptotic effects. Wild type and IL-10 knockout mice were treated with bacterial lipopolysaccharide and sacrificed 1, 4, 8, and 12 h later. Plasma ALT activity was measured as a marker of liver injury. Liver pathology and TUNEL response were assessed by histology. Plasma levels and whole liver mRNA levels were measured for TNF-alpha, IL-1 beta, TGF-beta1, IL-10, and their respective receptors. Hepatic mRNA levels were measured for several pro-apoptotic adaptors/regulators, including FasL, Fas receptor, FADD, TRADD, Bad, Bak, Bax, and Bcl-X(S), and anti-apoptotic regulators, including Bcl-w, Bcl-X(L), Bcl-2, and Bfl-1. Caspase-3 activity in the liver was determined as well as immunohistochemistry for IL-1RII, TGF-betaRII and Fas receptor. At all time points the livers from IL-10 knockout mice displayed a significantly increased number of apoptotic nuclei compared to wild type mice. Changes in plasma cytokine levels and their liver mRNA levels were consistent with suppression by IL-10 of pro-inflammatory cytokine secretion. In addition, pro-inflammatory cytokine receptor mRNA levels (TNF-alpha, TGF-beta, and IL-1 beta) were markedly up-regulated by LPS at all time points in IL-10 knockout mice as compared to wild type mice. Expression of the pro-inflammatory cytokine receptor IL-1RII was similarly increased as shown by immunostaining. The mRNA levels of a typical pro-apoptotic cytokine, TRAIL, were increased and LPS also up-regulated the mRNA expression of other apoptotic factors to a larger extent in IL-10 knockout mice than in their wild type counterparts, suggestive of an IL-10 anti-apoptotic effect. In the livers of knockout mice, markedly increased caspase-3 activity was already evident at the 1-h time point following LPS administration, while in the wild type animals this increase was delayed. Immunostaining also indicated that LPS increased hepatic expression of the pro-apoptotic receptors Fas and TGF-betaRII in IL-10 knockout mice. The data presented in this study show that: (i) IL-10 modulates not only the secretion of pro-inflammatory cytokines, but also the receptors of these cytokines, and ii) IL-10 protects the liver against LPS-induced injury at least in part by counteracting pro-inflammatory cytokine-induced liver apoptosis.
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PMID:Lipopolysaccharide-induced liver apoptosis is increased in interleukin-10 knockout mice. 1649 87

A protective effect of Rho-kinase inhibitor on various organ injuries is gaining attention. Regarding liver injury, Rho-kinase inhibitor is reported to prevent carbon tetrachloride (CCl4)- or dimethylnitrosamine-induced liver fibrosis and hepatic ischemia-reperfusion injury in rats. Because Rho-kinase inhibitor not only improved liver fibrosis but also reduced serum alanine aminotransferase (ALT) level in CCl4-induced liver fibrosis, we wondered whether Rho-kinase inhibitor might exert a direct hepatocyte-protective effect. We examined this possibility in acute CCl4 intoxication in rats. Rho-kinase inhibitor, HA-1077, reduced serum alanine ALT level in rats with acute liver injury induced by CCl4 with the improvement of histological damage and the reduction of the number of apoptotic cells. In cultured rat hepatocytes in serum-free condition, HA-1077 reduced apoptosis evaluated by quantitative determination of cytoplasmic histone-associated DNA oligonucleosome fragments with the reduction of caspase-3 activity and the enhancement of Bcl-2 expression. HA-1077 stimulated phosphorylation of Akt, and wortmannin, an inhibitor of phosphatidylinositol 3-kinase (PI3-kinase)/Akt pathway, abrogated the reduction of hepatocyte apoptosis by HA-1077 in vitro. Furthermore, wortmannin abrogated the reduction of serum ALT level by HA-1077 in rats with acute liver injury induced by CCl4, suggesting that the activation of PI3-kinase/Akt pathway may be involved in the hepatocyte-protective effect by Rho-kinase inhibitor in vivo. In conclusion, Rho-kinase inhibitor prevented hepatocyte damage in acute liver injury induced by CCl4 in rats and merits consideration as a hepatocyte-protective agent in liver injury, considering its direct antiapoptotic effect on hepatocytes in vitro.
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PMID:Rho-kinase inhibitor prevents hepatocyte damage in acute liver injury induced by carbon tetrachloride in rats. 1776 35

The differences and similarities of the pathogenesis of alcoholic (ASH) and non-alcoholic steatohepatitis (NASH) were examined. Mice (six/group) received one of four Lieber-Decarli liquid diets for 6 weeks: (1) paired-fed control diet; (2) control diet with ethanol (ethanol); (3) paired-fed methionine/choline deficient (MCD) diet; and (4) MCD plus ethanol (combination). Hepatotoxicity, histology, and gene expression changes were examined. Both MCD and ethanol induced macrovesicular steatosis. However, the combination diet produced massive steatosis with minor necrosis and inflammation. MCD and combination diets, but not ethanol, induced serum ALT levels by 1.6- and 10-fold, respectively. MCD diet, but not ethanol, also induced serum alkaline phosphatase levels suggesting bile duct injury. Ethanol increased liver fatty acid binding protein (L-FABP) mRNA and protein levels. In contrast, the combination diet decreased L-FABP mRNA and protein levels and increased hepatic free fatty acid and lipid peroxide levels. Ethanol, but not MCD, reduced hepatic S-adenosylmethionine (SAM) and GSH levels. Hepatic TNFalpha protein levels were increased in all treatment groups, however, IL-6, a hepatoprotective cytokine which promotes liver regeneration was increased in ethanol-fed mice (2-fold), but decreased in the combination diet-treated mice. In addition, the combination diet reduced phosphorylated STAT3 and Bcl-2 levels. While MCD diet might cause bile duct injury and cholestasis, ethanol preferentially interferes with the SAM-GSH oxidative stress pathway. The exacerbated liver injury induced by the combination diet might be explained by reduced L-FABP, increased free fatty acids, oxidative stress, and decreased IL-6 protein levels. The combination diet is an efficient model of steatohepatitis.
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PMID:The pathogenesis of ethanol versus methionine and choline deficient diet-induced liver injury. 1803 73

The modulation influence of Misgurnus anguillicaudatus polysaccharide on the expression of nitric oxide synthase (NOS), B cell lymphoma/leukemia-2 (Bcl-2, hepatocyte apoptosis inhibitor) and Bcl-2 associated X protein (Bax, hepatocyte apoptosis promoter) in mice's liver with immunological hepatic injury was studied. Immunological hepatic injury was induced by lipopolysaccharide (LPS ip, 0.2 mg kg(-1)) in bacillus calmette-guerin (BCG ip, 0.15 g kg(-1), once, before 7 days) primed mice. The mice were treated with M. anguillicaudatus polysaccharides (MAP) at doses of 30 mg kg(-1), 60 mg kg(-1), respectively, ig, once a day, and sacrificed on the 8th day after ip LPS for 4 h. In comparison to the normal mice, the nitric oxide production, serum alanine aminotransferase (sALT) and serum glutathione s-transferase (sGST) levels were increased significantly, iNOS and Bax expression were up-regulated by 16.5 times (P<0.001 vs. normal animal group) and 0.43 times (P<0.05, vs. normal animal group) respectively, cNOS expression was not apparently changed, and no Bcl-2 expression was found in immunological hepatic injury mice. The M. anguillicaudatus polysaccharide (30 mg kg(-1)) could reduce sALT, sGST and nitric oxide production levels (vs. BCG-LPS model control group) by 25.1%, 42.6% and 17.8% respectively, and the expression of iNOS and Bax was decreased (vs. BCG-LPS model control group) by 80.3% and 38.4%, while the expression of cNOS and Bcl-2 increased (vs. BCG-LPS model control group) by 58.7% and 352%, respectively.
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PMID:Protective effect of Misgurnus anguillicaudatus polysaccharide on immunological liver injury in mice. 1838 2

Hydrogen sulfide (H(2)S) is an endogenously produced gaseous signaling molecule with diverse physiological activity. The potential protective effects of H(2)S have not been evaluated in the liver. The purpose of the current study was to investigate if H(2)S could afford hepatoprotection in a murine model of hepatic ischemia-reperfusion (I/R) injury. Hepatic injury was achieved by subjecting mice to 60 min of ischemia followed by 5 h of reperfusion. H(2)S donor (IK1001) or vehicle were administered 5 min before reperfusion. H(2)S attenuated the elevation in serum alanine aminotransferase (ALT) by 68.6% and aspartate aminotransferase (AST) by 70.8% compared with vehicle group. H(2)S-mediated cytoprotection was associated with an improved balance between reduced glutathione (GSH) vs. oxidized glutathione (GSSG), an attenuated formation of lipid hydroperoxides, and an increased expression of thioredoxin-1 (Trx-1). Furthermore, H(2)S inhibited the progression of apoptosis after I/R injury by increasing the protein expression of heat shock protein (HSP-90) and Bcl-2. These results indicate that H(2)S protects the murine liver against I/R injury through an upregulation of intracellular antioxidant and antiapoptotic signaling pathways.
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PMID:Hydrogen sulfide attenuates hepatic ischemia-reperfusion injury: role of antioxidant and antiapoptotic signaling. 1856 6

To gain insight into the processes by which severe acute pancreatitis induced apoptosis takes place in the liver, and to observe the protective effect of resveratrol on hepatic injury, a rat model of severe acute pancreatitis was induced by administering 4% sodium taurocholate through the common biliopancreatic duct. Pancreatic and hepatic injury was assessed by histology. Serum ALT (alanine aminotransferase), AST (aspartate aminotransferase) and total bilirubin were determined by reaction rate assay, and the serum levels of TNF-alpha (tumor necrosis factor-alpha) and IL-6 (interleukin-6) were detected by ELISA (enzyme linked immunosorbent assay). We investigated cytochrome c released from mitochondria and used the RT-PCR (reverse transcription PCR), Western blot technique to evaluate Bax, Bcl-2, and caspase-3 expression levels in hepatic tissue over the time course of apoptosis. Changes in hepatic cell mitochondrial membrane potential were observed by confocal laser scanning microscopy. The majority of cytochrome c release occurred early in apoptosis from mitochondria, which undergo gradual hepatic impairment. The released cytochrome c can be reduced by resveratrol through both up-regulation of Bcl-2 and down-regulation of Bax and caspase-3. These data provide substantial evidence that apoptosis is involved in hepatic injury during the severe acute pancreatitis process and that resveratrol can ameliorate the situation, thus protecting liver function in rats with severe acute pancreatitis.
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PMID:Resveratrol ameliorates hepatic injury via the mitochondrial pathway in rats with severe acute pancreatitis. 1897 15

Prostaglandin E1 (PGE1) has wide-ranging effects on cytoprotection and may play a role in preventing liver failure following excessive hepatectomy. We examined the effect of PGE1 on hepatocyte apoptosis and liver regeneration after 95% hepatectomy in a rat model. PGE1 or vehicle was intravenously administered 30 minutes before and during hepatectomy. The extent of hepatocyte injury was evaluated by serum alanine aminotransferase and aspartate aminotransferase levels. To evaluate hepatocyte apoptosis and liver regeneration, terminal deoxynucleotidyl transferase dUTP nick end labeling staining and Ki67 labeling were performed. The expression levels of Bcl-xL, Bcl-2, Bax, Cyclin C, Cyclin D1, Cyclin E, p21, transforming growth factor-beta, plasminogen activator inhibitor-1, and glyceraldehyde-2-phosphate dehydrogenase mRNA were also examined by reverse transcription-polymerase chain reaction. Survival was improved in the PGE1 group (26.6%), whereas all rats in the vehicle group died within 60 hours. PGE1 significantly suppressed the release of alanine aminotransferase and aspartate aminotransferase at 12 hours postoperatively. Pretreatment with PGE1 significantly increased the Ki67-positive cell count and decreased the terminal deoxynucleotidyl transferase dUTP nick end labeling positive cell count after hepatectomy, and also significantly increased the expression levels of Bcl-xL, Cyclin C, and Cyclin D1. Our results suggest that pretreatment with PGE1 may increase survival following hepatectomy by salvaging the remaining liver tissue, which it does by inhibiting apoptosis and stimulating hepatocyte proliferation.
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PMID:Prostaglandin E1 prevents liver failure after excessive hepatectomy in the rat by up-regulating Cyclin C, Cyclin D1, and Bclxl. 1915 52


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