Rapamycin antagonizes NF-kappaB nuclear translocation activated by TNF-alpha in primary vascular smooth muscle cells and enhances apoptosis.
Several lines of evidence support the view that rapamycin inhibits NF-kappaB. TNF-alpha, a potent inducer of NF-kappaB, is released after artery injury (e.g., balloon angioplasty) and plays an important role in inflammation and restenosis. We investigated the effect of rapamycin on NF-kappaB activation and apoptosis in vascular smooth muscle cells (VSMCs) stimulated with TNF-alpha. Using EMSA, we found that TNF-alpha caused NF-kappaB nuclear translocation in VSMCs after 1 h of incubation. Rapamycin inhibited IkappaBalpha degradation, thereby preventing nuclear translocation. Activation of NF-kappaB was accompanied by an increase of Bcl-xL and Bfl-1/A1 proteins, detected by Western blot assay, whereas rapamycin prevented the TNF-alpha-induced enhancement of these antiapoptotic proteins. The extent of apoptosis of VSMCs exposed to TNF-alpha was significantly enhanced by rapamycin. The effect of rapamycin appeared to be independent of the phosphatidylinositol 3-kinase/Akt-protein kinase B survival pathway, because the phosphatidylinositol 3-kinase inhibitor wortmannin neither prevented IkappaBalpha degradation nor increased apoptosis of cells incubated with TNF-alpha. Finally, we demonstrate that the large immunophilin FK-506 binding protein FKBP51 is essential for TNF-alpha-induced NF-kappaB activation in VSMCs. Our findings show that rapamycin inhibits NF-kappaB activation and acts in concert with TNF-alpha in induction of VSMC apoptosis.
Giordano
Arturo
A
Department of Biochemistry and Medical Biotechnology, University of Naples Federico II, via S. Pansini 5, 80131 Naples, Italy.
Avellino
Raffaella
R
Ferraro
Paolo
P
Romano
Simona
S
Corcione
Nicola
N
Romano
Maria Fiammetta
MF
D000818:Animals; D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D017209:Apoptosis / Q000187:drug effects*; D015153:Blotting, Western; D002478:Cells, Cultured; D024202:Electrophoretic Mobility Shift Assay; D051550:I-kappa B Kinase / Q000378:metabolism; D007166:Immunosuppressive Agents / Q000378:metabolism; D008297:Male; D009131:Muscle, Smooth, Vascular / Q000166:cytology / Q000378:metabolism*; D016328:NF-kappa B / Q000187:drug effects*; D016759:Oncogene Protein p65(gag-jun) / Q000235:genetics; D034741:RNA, Small Interfering / Q000627:therapeutic use; D051381:Rats; D017208:Rats, Wistar; D015398:Signal Transduction / Q000187:drug effects; D020123:Sirolimus / Q000494:pharmacology*; D016559:Tacrolimus / Q000378:metabolism; D022021:Tacrolimus Binding Proteins / Q000378:metabolism; D014162:Transfection; D014178:Translocation, Genetic / Q000187:drug effects*; D014409:Tumor Necrosis Factor-alpha / Q000494:pharmacology*; D051020:bcl-X Protein / Q000235:genetics; D000099159:Tacrolimus Binding Protein 5
D000900:Anti-Bacterial Agents; D051550:I-kappa B Kinase; D007166:Immunosuppressive Agents; D016328:NF-kappa B; D016759:Oncogene Protein p65(gag-jun); D034741:RNA, Small Interfering; D020123:Sirolimus; D016559:Tacrolimus; D022021:Tacrolimus Binding Proteins; D014409:Tumor Necrosis Factor-alpha; D051020:bcl-X Protein; D000099159:Tacrolimus Binding Protein 5