title: Oxidative stress induces the endoplasmic reticulum stress and facilitates inclusion formation in cultured cells.
abstract: OBJECTIVE
  The precise mechanism of formation and significance of Mallory bodies (MBs) are poorly understood. The endoplasmic reticulum (ER) is the organelle responsible for proper folding and elimination of unfolded proteins. Therefore, failure of this function increases defective proteins in the cell.
  
  
  METHODS
  We examined the effects of oxidative stress on induction of ER stress and keratin 8 and 18 (K8/18)-containing inclusion formation in cultured human hepatoma cells and hepatocytes by immunofluorescence and immunoblot analyses.
  
  
  RESULTS
  Generation of H(2)O(2) was detected in glucose oxidase (GO)-treated cells by 2',7'-dichlorodihydrofluorescein diacetate and co-treatment with GO and acetyl-leucyl-leucyl-norleucinal (ALLN), a proteasome inhibitor, induced formation of extensive keratin inclusions that were inhibited by pre-treatment with N-acetyl-cysteine. These inclusions shared similar features with MBs by immunofluorescence analysis. Electron microscopy showed that these structures appeared near the nuclei, surrounded by filamentous structures. GO and ALLN upregulated the expression of ER stress markers, however, 4-phenylbutyrate, a chemical chaperone, reduced formation of inclusions and expression of the ER stress markers.
  
  
  CONCLUSIONS
  The oxidative stress coupled with limited inhibition of the proteasome induces dysfunction of the ER and results in inclusion formation in cultured cells. This suggests that ER stress plays a role in MB formation in liver disease.
authors: Department of Medicine, Kurume University School of Medicine, and Research Center for Innovative Cancer Therapy, and Center of the 21st Century COE Program for Medical Science, Kurume University, Kurume, Japan. hanadas@med.kurume-u.ac.jp
authors: Shinichiro
authors: S
authors: Hanada
authors: Masaru
authors: M
authors: Harada
authors: Hiroto
authors: H
authors: Kumemura
authors: M
authors: M
authors: Bishr Omary
authors: Hironori
authors: H
authors: Koga
authors: Takumi
authors: T
authors: Kawaguchi
authors: Eitaro
authors: E
authors: Taniguchi
authors: Takafumi
authors: T
authors: Yoshida
authors: Takao
authors: T
authors: Hisamoto
authors: Chikatoshi
authors: C
authors: Yanagimoto
authors: Michiko
authors: M
authors: Maeyama
authors: Takato
authors: T
authors: Ueno
authors: Michio
authors: M
authors: Sata
mesh_terms: D015853:Cysteine Proteinase Inhibitors / Q000494:pharmacology; D004721:Endoplasmic Reticulum / Q000378:metabolism* / Q000648:ultrastructure; D005452:Fluoresceins / Q000494:pharmacology; D005949:Glucose Oxidase / Q000494:pharmacology; D006801:Humans; D006861:Hydrogen Peroxide / Q000378:metabolism; D002479:Inclusion Bodies / Q000737:chemistry / Q000378:metabolism* / Q000648:ultrastructure; D053538:Keratin-18 / Q000032:analysis; D053533:Keratin-8 / Q000032:analysis; D007976:Leupeptins / Q000494:pharmacology; D008107:Liver Diseases / Q000378:metabolism* / Q000473:pathology; D018384:Oxidative Stress; D010654:Phenylbutyrates / Q000378:metabolism; D061988:Proteasome Inhibitors; D014407:Tumor Cells, Cultured
chemical_list: C110400:2',7'-dichlorodihydrofluorescein diacetate; D015853:Cysteine Proteinase Inhibitors; D005452:Fluoresceins; D053538:Keratin-18; D053533:Keratin-8; D007976:Leupeptins; D010654:Phenylbutyrates; D061988:Proteasome Inhibitors; C063261:acetylleucyl-leucyl-norleucinal; C075773:4-phenylbutyric acid; D006861:Hydrogen Peroxide; D005949:Glucose Oxidase