Rapamycin-FKBP inhibits cell cycle regulators of proliferation in vascular smooth muscle cells.
Multiple growth factors can stimulate quiescent vascular smooth muscle cells to exit from G0 and reenter the cell cycle. The macrolide antibiotic rapamycin, bound to its cytosolic receptor FKBP, is an immunosuppressant and a potent inhibitor of cellular proliferation. In the present study, the antiproliferative effects of rapamycin on human and rat vascular smooth muscle cells were examined and compared with the effects of a related immunosuppressant, FK520. In vascular smooth muscle cells, rapamycin, at concentrations as low as 1 ng/mL, inhibited DNA synthesis and cell growth. FK520, an analogue of the immunosuppressant FK506, is structurally related to rapamycin and binds to FKBP but did not inhibit vascular smooth muscle cell growth. Molar excesses of FK520 blocked the antiproliferative effects of rapamycin, indicating that the effects of rapamycin required binding to FKBP. Rapamycin-FKBP inhibited retinoblastoma protein phosphorylation at the G1/S transition. This inhibition of retinoblastoma protein phosphorylation was associated with a decrease in p33cdk2 kinase activity. These observations suggest that rapamycin, but not FK520, inhibits vascular smooth muscle cell proliferation by reducing cell-cycle kinase activity.
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Department of Medicine, Mount Sinai School of Medicine, New York, NY 10029.
Jayaraman
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D000818:Animals; D016203:CDC2 Protein Kinase / Q000502:physiology; D042846:CDC2-CDC28 Kinases; D002352:Carrier Proteins / Q000494:pharmacology; D002453:Cell Cycle / Q000187:drug effects; D002455:Cell Division / Q000187:drug effects; D002478:Cells, Cultured; D019938:Cyclin D1; D051357:Cyclin-Dependent Kinase 2; D018844:Cyclin-Dependent Kinases / Q000502:physiology; D016213:Cyclins / Q000502:physiology; D004268:DNA-Binding Proteins / Q000494:pharmacology; D006360:Heat-Shock Proteins / Q000494:pharmacology; D006801:Humans; D007166:Immunosuppressive Agents / Q000494:pharmacology*; D009131:Muscle, Smooth, Vascular / Q000166:cytology / Q000187:drug effects*; D015513:Oncogene Proteins / Q000502:physiology; D010766:Phosphorylation; D011090:Polyenes / Q000494:pharmacology*; D017346:Protein Serine-Threonine Kinases / Q000502:physiology; D051381:Rats; D016160:Retinoblastoma Protein / Q000378:metabolism; D020123:Sirolimus; D016559:Tacrolimus / Q000031:analogs & derivatives* / Q000494:pharmacology; D022021:Tacrolimus Binding Proteins
D002352:Carrier Proteins; D016213:Cyclins; D004268:DNA-Binding Proteins; D006360:Heat-Shock Proteins; D007166:Immunosuppressive Agents; D015513:Oncogene Proteins; D011090:Polyenes; D016160:Retinoblastoma Protein; D019938:Cyclin D1; C058028:immunomycin; D017346:Protein Serine-Threonine Kinases; D016203:CDC2 Protein Kinase; D042846:CDC2-CDC28 Kinases; C495894:CDK2 protein, human; C495892:Cdk2 protein, rat; D051357:Cyclin-Dependent Kinase 2; D018844:Cyclin-Dependent Kinases; D022021:Tacrolimus Binding Proteins; D020123:Sirolimus; D016559:Tacrolimus