Inhibition of NFkappaB in activated rat hepatic stellate cells by proteasome inhibitors and an IkappaB super-repressor

Hepatology. 1998 May;27(5):1285-95. doi: 10.1002/hep.510270514.


The hepatic stellate cell (HSC), following a fibrogenic stimulus, is transformed from a quiescent to an activated cell. Cytokines induce NFkappaB activity in activated but not in quiescent HSCs with subsequent expression of NFkappaB-responsive genes, such as intercellular adhesion molecule (ICAM)-1 and interleukin (IL)-6. We investigated the effect of proteasome inhibitors and an IkappaB super-repressor on the cytokine mediated activation of NFkappaB, ICAM-1, and IL-6 in activated HSCs. Culture-activated HSCs were stimulated with IL-1beta or tumor necrosis factor alpha (TNFalpha) in the presence or absence of proteasome inhibitors, ALLN or MG-132, or after infection with an adenovirus expressing the IkappaB super-repressor (Ad5IkappaB) or beta-galactosidase (Ad5LacZ) as a control. NFkappaB activity was evaluated by immunofluorescence and by electrophoretic mobility shift assay. The steady state level of cytoplasmic IkappaB protein was measured by Western Blot. ICAM-1 and IL-6 expression was measured by reverse transcriptase-polymerase chain reaction and enzyme-linked immunosorbant assay. Proteasome inhibitors, which block the degradation of IkappaB, and the Ad5IkappaB, which provides an exogenous nondegradable IkappaB, block the stimulation of NFkappaB activity by TNFalpha and IL-1beta in activated HSCs. These reagents block the subsequent nuclear translocation of p65 NFkappaB and induction of ICAM-1 and IL-6 by cytokines. The specificities of the proteasome inhibitors and the IkappaB super-repressor are demonstrated by their failure to block c-Jun N-terminal kinase induction by cytokines. Cytokine-induced stimulation of NFkappaB, ICAM-1, and IL-6 is blocked by proteasome inhibitors and Ad5IkappaB in activated HSCs. Inhibition of IkappaBalpha degradation is a potential target for anti-inflammatory therapy in the liver and might influence the activation process of HSCs following fibrotic stimuli.

Publication types

  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Animals
  • Cells, Cultured
  • Cysteine Endopeptidases / physiology*
  • Cysteine Proteinase Inhibitors / pharmacology
  • DNA-Binding Proteins / metabolism
  • Gene Expression Regulation
  • Intercellular Adhesion Molecule-1 / genetics
  • Intercellular Adhesion Molecule-1 / metabolism
  • Interleukin-6 / genetics
  • Interleukin-6 / metabolism
  • Leupeptins / pharmacology
  • Liver / cytology*
  • Liver Cirrhosis, Experimental / pathology
  • Male
  • Multienzyme Complexes / physiology*
  • NF-kappa B / metabolism*
  • Oligopeptides / pharmacology
  • Proteasome Endopeptidase Complex
  • Proto-Oncogene Proteins / metabolism*
  • RNA, Messenger / genetics
  • Rats
  • Rats, Sprague-Dawley
  • Transcription Factor RelB
  • Transcription Factors*


  • Cysteine Proteinase Inhibitors
  • DNA-Binding Proteins
  • Interleukin-6
  • Leupeptins
  • Multienzyme Complexes
  • NF-kappa B
  • Oligopeptides
  • Proto-Oncogene Proteins
  • RNA, Messenger
  • Relb protein, rat
  • Transcription Factors
  • Intercellular Adhesion Molecule-1
  • Transcription Factor RelB
  • Cysteine Endopeptidases
  • Proteasome Endopeptidase Complex
  • benzyloxycarbonylleucyl-leucyl-leucine aldehyde