title: Autophagy is involved in endoplasmic reticulum stress-induced cell death of rat hepatocytes.
abstract: BACKGROUND
  Both endoplasmic reticulum (ER) stress and autophagy have been shown to display dual roles in cell survival in multiple cell lines. There is a reported but poorly understood link between ER stress, autophagy, and cell death. We hypothesized that autophagy plays a role in ER stress-dependent cell death in rat hepatocytes.
  
  
  METHODS
  Primary hepatocytes isolated from both lean and obese male Zucker rats were cultured and treated with tunicamycin (TM), tauroursodeoxycholic acid, 3-methyladenine, and wortmannin for 12 h. The ER stress-associated genes glucose-regulated protein 78 and C/EBP homologous protein were examined via quantitative real time polymerase chain reaction. Immunostaining with microtubule-associated protein 1 light chain 3 as well as electron microscopy were used to evaluate autophagy activity. Trypan blue exclusion was used to determine hepatocyte cell viability.
  
  
  RESULTS
  In both lean and steatotic hepatocytes, we found that TM induced both C/EBP homologous protein and glucose-regulated protein 78 messenger RNA expression. Cells with increased ER stress were undergoing increased autophagy and had a significant decrease in cell viability. Both tauroursodeoxycholic acid and 3-methyladenine treatments attenuated TM induced ER stress, autophagy, and cell death, whereas wortmannin treatment reduced autophagy and cell death but without changing ER stress.
  
  
  CONCLUSIONS
  These data suggest that autophagy is a likely downstream mediator of ER stress-induced cell death in rat hepatocytes. Further exploration of the link between autophagy and ER stress in hepatocyte injury will yield important information that may be leveraged for treatment of liver injuries such as ischemia/reperfusion.
authors.affiliation: Division of Transplant and Hepatobiliary Surgery, Department of Surgery, University of Mississippi Medical Center, Jackson, MS 39216, USA.
authors.forename: Junlin
authors.initials: J
authors.lastname: Zhang
authors.forename: Michael W
authors.initials: MW
authors.lastname: Morris
authors.forename: Wanda A
authors.initials: WA
authors.lastname: Dorsett-Martin
authors.forename: Luke C
authors.initials: LC
authors.lastname: Drake
authors.forename: Christopher D
authors.initials: CD
authors.lastname: Anderson
mesh_terms: D000225:Adenine / Q000031:analogs & derivatives / Q000494:pharmacology; D000730:Androstadienes / Q000494:pharmacology; D000818:Animals; D017209:Apoptosis / Q000187:drug effects / Q000502:physiology*; D001343:Autophagy / Q000187:drug effects / Q000502:physiology*; D002470:Cell Survival / Q000187:drug effects / Q000502:physiology; D002478:Cells, Cultured; D004195:Disease Models, Animal; D059865:Endoplasmic Reticulum Stress / Q000187:drug effects / Q000502:physiology*; D005234:Fatty Liver / Q000473:pathology*; D022781:Hepatocytes / Q000187:drug effects / Q000473:pathology*; D008297:Male; D051381:Rats; D011924:Rats, Zucker; D013655:Taurochenodeoxycholic Acid / Q000494:pharmacology; D014415:Tunicamycin / Q000494:pharmacology; D000077191:Wortmannin
chemical_list: D000730:Androstadienes; D014415:Tunicamycin; C025946:3-methyladenine; D013655:Taurochenodeoxycholic Acid; C031655:ursodoxicoltaurine; D000225:Adenine; D000077191:Wortmannin
keywords: Autophagy; ER stress; Hepatocyte cell death; Lean; Steatotic
references.citation: Free Radic Biol Med. 2009 Apr 15;46(8):1158-67
references.pmid: 19439225
references.citation: Arch Toxicol. 2009 Feb;83(2):151-9
references.pmid: 18696052
references.citation: J Biol Chem. 2012 May 4;287(19):15661-71
references.pmid: 22433868
references.citation: Nature. 2008 Feb 28;451(7182):1069-75
references.pmid: 18305538
references.citation: Antioxid Redox Signal. 2011 Jun;14(11):2191-200
references.pmid: 20726815
references.citation: Autophagy. 2009 Apr;5(3):351-60
references.pmid: 19158494
references.citation: EMBO Rep. 2006 Sep;7(9):880-5
references.pmid: 16953201
references.citation: J Biol Chem. 2007 Feb 16;282(7):4702-4710
references.pmid: 17135238
references.citation: Cell. 2007 Jun 29;129(7):1337-49
references.pmid: 17604722
references.citation: Annu Rev Genet. 2009;43:67-93
references.pmid: 19653858
references.citation: Exp Cell Res. 2001 Jul 15;267(2):193-204
references.pmid: 11426938
references.citation: Genes Dev. 1998 Apr 1;12(7):982-95
references.pmid: 9531536
references.citation: Biochem Biophys Res Commun. 2012 Oct 26;427(3):485-9
references.pmid: 23000413
references.citation: J Lipid Res. 2009 Sep;50(9):1721-34
references.pmid: 19417220
references.citation: Nat Cell Biol. 2011 Mar;13(3):184-90
references.pmid: 21364565
references.citation: Annu Rev Biochem. 2005;74:739-89
references.pmid: 15952902
references.citation: Liver Transpl. 2011 Feb;17(2):189-200
references.pmid: 21280192
references.citation: Genes Dev. 2007 Nov 15;21(22):2861-73
references.pmid: 18006683
references.citation: Arch Histol Cytol. 2005;68(1):71-80
references.pmid: 15827380
references.citation: Cell Death Differ. 2008 Sep;15(9):1460-71
references.pmid: 18551133
references.citation: Autophagy. 2009 Nov;5(8):1217-9
references.pmid: 19829057
references.citation: Cell Metab. 2010 Jun 9;11(6):467-78
references.pmid: 20519119
references.citation: PLoS Biol. 2006 Nov;4(11):e374
references.pmid: 17090218
references.citation: Mol Cell Biol. 2001 Feb;21(4):1249-59
references.pmid: 11158311
references.citation: J Clin Invest. 2009 May;119(5):1359-72
references.pmid: 19425170
references.citation: Int J Cell Biol. 2010;2010:930509
references.pmid: 20145727
references.citation: Am J Physiol Endocrinol Metab. 2010 May;298(5):E1027-35
references.pmid: 20159858
references.citation: Viruses. 2012 Oct 19;4(10):2251-90
references.pmid: 23202463
references.citation: Autophagy. 2010 Feb;6(2):239-47
references.pmid: 20104019
references.citation: Mol Cell Biol. 2006 Dec;26(24):9220-31
references.pmid: 17030611
references.citation: Nat Rev Mol Cell Biol. 2007 Jul;8(7):519-29
references.pmid: 17565364
references.citation: J Clin Invest. 2005 Oct;115(10):2679-88
references.pmid: 16200202