In vivo altered unfolded protein response and apoptosis in livers from lipopolysaccharide-challenged cirrhotic rats.

INSERM U773, Centre de Recherche Bichat-Beaujon CRB3, Paris 75018, France.
Journal of Hepatology (Impact Factor: 9.86). 06/2007; 46(6):1075-88. DOI: 10.1016/j.jhep.2007.01.034
Source: PubMed

ABSTRACT Endoplasmic reticulum (ER)-related unfolded protein response (UPR) is mediated by PKR-like ER kinase (PERK), ATF6 and IRE1. PERK phosphorylates eukaryotic translation initiation factor-2alpha (eIF2alpha) to attenuate protein synthesis, including in NF-kappaB-dependent antiapoptotic proteins. We hypothesized that an altered UPR in the liver may sensitize cirrhotic livers to LPS-induced, TNFalpha-mediated apoptosis. Thus, we examined in vivo UPR and NF-kappaB activity in livers from cirrhotic and normal LPS-challenged rats.
Livers were harvested in rats that did or did not receive LPS.
Under baseline conditions, no UPR was found in normal livers while PERK/eIF2alpha and ATF6 pathways were activated in cirrhotic livers. After LPS, in normal livers, the PERK/eIF2alpha pathway was transiently activated. ATF6 and IRE1 were activated. In cirrhotic livers, the PERK/eIF2alpha pathway remained elevated. ATF6 and IRE1 pathways were altered. LPS-induced, NF-kappaB-dependent antiapoptotic proteins increased in normal livers whereas their expression was blunted at the posttranscriptional level in cirrhotic livers.
Cirrhotic livers exhibit partial UPR activation in the basal state and full UPR, although altered, after LPS challenge. Sustained eIF2alpha phosphorylation, a hallmark of cirrhotic liver UPR, is associated with a lack of LPS-induced accumulation of NF-kappaB-dependent antiapoptotic proteins which may sensitize cirrhotic livers to LPS/TNFalpha-mediated apoptosis.

  • [Show abstract] [Hide abstract]
    ABSTRACT: Alcohol-induced liver disease increasingly contributes to human mortality worldwide. Alcohol-induced endoplasmic reticulum (ER) stress and disruption of cellular protein homeostasis have recently been established as a significant mechanism contributing to liver diseases. The alcohol-induced ER stress occurs not only in cultured hepatocytes but also in vivo in the livers of several species including mouse, rat, minipigs, zebrafish, and humans. Identified causes for the ER stress include acetaldehyde, oxidative stress, impaired one carbon metabolism, toxic lipid species, insulin resistance, disrupted calcium homeostasis, and aberrant epigenetic modifications. Importance of each of the causes in alcohol-induced liver injury depends on doses, duration and patterns of alcohol exposure, genetic disposition, environmental factors, cross-talks with other pathogenic pathways, and stages of liver disease. The ER stress may occur more or less all the time during alcohol consumption, which interferes with hepatic protein homeostasis, proliferation, and cell cycle progression promoting development of advanced liver diseases. Emerging evidence indicates that long-term alcohol consumption and ER stress may directly be involved in hepatocellular carcinogenesis (HCC). Dissecting ER stress signaling pathways leading to tumorigenesis will uncover potential therapeutic targets for intervention and treatment of human alcoholics with liver cancer.
    International journal of hepatology. 01/2014; 2014:513787.
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: To examine the epidemiologic and clinical characteristics of hepatitis B virus (HBV) related liver failure in patients in China. This study was conducted with a retrospective design to examine 1066 patients with HBV-related liver failure in the southwest of China. There were more male than female patients. Young and middle-aged people comprised most of the patients. Farmers and laborers comprised the largest proportion (63.09%). Han Chinese accounted for 98.12%, while minority ethnic groups only accounted for 0.88% of patients. A total of 43.47% patients had a family history of HBV-related liver failure and 56.66% patients had a history of drinking alcohol. A total of 42.59% patients with HBV-related liver failure had definite causes. With regard to the clinical manifestation of HBV-related liver failure, the symptoms were: hypodynamia, anorexia and abdominal distension. Total bilirubin (TBIL) and alanine aminotransferase (ALT) levels were altered in 46.23% of patients with evident damage of the liver. Univariate logistic regression analysis showed that the patients' prognoses were correlated with ALT, aspartate aminotransferase, albumin, TBIL, prothrombin activity (PTA), and alpha-fetoprotein levels, and drinking alcohol, ascites, hepatorenal syndrome, infection and ≥ 2 complications. Multifactor logistic regression analysis showed that the activity of thrombinogen and the number of complications were related to the prognosis. Alcohol influences the patients' prognosis and condition. PTA and complications are independent factors that can be used for estimating the prognosis of HBV-related liver failure.
    World Journal of Gastroenterology 07/2011; 17(25):3054-9. · 2.55 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: When cells are subjected to stress by changes in their extracellular environment, unfolded proteins accumulate in the endoplasmic reticulum (ER), causing ER stress. This initiates the unfolded protein response (UPR), a signal transduction cascade aiming at restoring cellular homeostasis. The UPR and angiogenesis are involved in the pathogenesis of many diseases such as cancer, pulmonary diseases and chronic liver diseases (CLDs) such as alcoholic liver disease, non-alcoholic steatohepatitis and hepatitis B. This review summarizes the upcoming knowledge of the interaction between the UPR and angiogenesis in physiological angiogenesis and in different CLDs and other diseases. This article is protected by copyright. All rights reserved.
    Liver international: official journal of the International Association for the Study of the Liver 01/2014; · 3.87 Impact Factor