Ubiquitin-proteasome pathway as a new target for the prevention of restenosis.
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.
Meiners
Silke
S
Medizinische Klinik und Poliklinik, Charité, Campus Mitte, Humboldt-Universität zu Berlin, Germany.
Laule
Michael
M
Rother
Wim
W
Guenther
Christoph
C
Prauka
Ines
I
Muschick
Peter
P
Baumann
Gert
G
Kloetzel
Peter-Michael
PM
Stangl
Karl
K
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*
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