title: Ubiquitin-proteasome pathway as a new target for the prevention of restenosis.
abstract: BACKGROUND
  The ubiquitin-proteasome system is the major intracellular protein degradation pathway in eucaryotic cells. It regulates central mediators of proliferation, inflammation, and apoptosis that are fundamental pathomechanisms in the development of vascular restenosis.
  
  
  RESULTS
  Effects of proteasome inhibition on neointima formation were studied in a balloon injury model in the rat carotid artery. Local application of the proteasome inhibitor MG132 (1 mmol/L) resulted in significant inhibition of intimal hyperplasia, that is, by 74% (P=0.008). This effect was accompanied by decreased proliferation, reduced infiltration of macrophages, and prolonged apoptosis, as determined by immunohistochemical and TUNEL analyses. Functional effects of proteasome inhibition on proliferation, activation of nuclear factor kappa B, and apoptosis were further characterized in rat primary vascular smooth muscle cells. MG132 dose-dependently inhibited vascular smooth muscle cell proliferation with 50% inhibition at 10 micromol/L. TNFalpha-induced degradation of IkappaBalpha and beta was blocked, and activation of nuclear factor kappa B was suppressed in a concentration-dependent manner in bandshift assays. Moreover, proteasome inhibition (1 to 50 micromol/L MG132) induced apoptotic cell death up to 80%, as confirmed by DNA/Histone-ELISA and TUNEL-FACS analysis. Specificity of proteasome inhibition was shown by accumulation of multiubiquitinylated proteins and accumulation of specific proteasomal substrates.
  
  
  CONCLUSIONS
  These proof-of-principle experiments demonstrate that inhibition of the ubiquitin-proteasome system effectively reduces neointima formation in vivo, which corresponds to strong antiproliferative, anti-inflammatory, and proapoptotic effects in vitro and in vivo. Our data suggest the ubiquitin-proteasome system as a new target in the prevention of vascular restenosis.
authors.affiliation: Medizinische Klinik und Poliklinik, Charité, Campus Mitte, Humboldt-Universität zu Berlin, Germany.
authors.forename: Silke
authors.initials: S
authors.lastname: Meiners
authors.forename: Michael
authors.initials: M
authors.lastname: Laule
authors.forename: Wim
authors.initials: W
authors.lastname: Rother
authors.forename: Christoph
authors.initials: C
authors.lastname: Guenther
authors.forename: Ines
authors.initials: I
authors.lastname: Prauka
authors.forename: Peter
authors.initials: P
authors.lastname: Muschick
authors.forename: Gert
authors.initials: G
authors.lastname: Baumann
authors.forename: Peter-Michael
authors.initials: PM
authors.lastname: Kloetzel
authors.forename: Karl
authors.initials: K
authors.lastname: Stangl
mesh_terms: D000800:Angioplasty, Balloon / Q000009:adverse effects; D000818:Animals; D017209:Apoptosis; D016893:Carotid Stenosis / Q000209:etiology / Q000473:pathology / Q000517:prevention & control; D002455:Cell Division / Q000187:drug effects; D002478:Cells, Cultured; D003546:Cysteine Endopeptidases; D015853:Cysteine Proteinase Inhibitors / Q000494:pharmacology*; D006083:Graft Occlusion, Vascular / Q000473:pathology / Q000517:prevention & control*; D007249:Inflammation / Q000517:prevention & control; D007976:Leupeptins / Q000494:pharmacology*; D009097:Multienzyme Complexes / Q000037:antagonists & inhibitors*; D009131:Muscle, Smooth, Vascular / Q000166:cytology / Q000187:drug effects / Q000378:metabolism; D016328:NF-kappa B / Q000037:antagonists & inhibitors; D046988:Proteasome Endopeptidase Complex; D051381:Rats; D017208:Rats, Wistar; D013379:Substrate Specificity; D025801:Ubiquitin / Q000037:antagonists & inhibitors*
chemical_list: D015853:Cysteine Proteinase Inhibitors; D007976:Leupeptins; D009097:Multienzyme Complexes; D016328:NF-kappa B; D025801:Ubiquitin; D003546:Cysteine Endopeptidases; D046988:Proteasome Endopeptidase Complex; C072553:benzyloxycarbonylleucyl-leucyl-leucine aldehyde