FKBP-rapamycin inhibits a cyclin-dependent kinase activity and a cyclin D1-Cdk association in early G1 of an osteosarcoma cell line.
Upon entering a cell the natural product rapamycin, like the structurally related immunosuppressant FK506, associates with members of the FKBP family of proteins. One or more of the resulting FKBP-rapamycin complexes blocks signaling pathways emanating from some growth factor receptors. Recently, the addition of rapamycin was shown to inhibit the phosphorylation and activation of a 70-kDa ribosomal S6 protein kinase, which normally occurs minutes after the activation of certain cytokine and growth factor receptors. We now report that rapamycin can be added 4 to 6 h after the addition of serum growth factors to quiescent human osteosarcoma cells and still arrest these cells in G1. This window of action correlates with the inducible appearance of a cyclin-dependent kinase (cdk) activity, and the induction of this activity is inhibited by the addition of rapamycin. Furthermore, p36cyclin D1 associates with this cdk protein complex in lysates of untreated cells, but does not associate with this cdk protein complex in lysates of rapamycin-treated cells. Together, these studies demonstrate that FKBP-rapamycin can modulate a cyclin-dependent kinase activity and a cyclin D1-cdk association during early G1 in MG-63 human osteosarcoma cells.
Albers
M W
MW
Department of Chemistry, Harvard University, Cambridge, Massachusetts 02138.
Williams
R T
RT
Brown
E J
EJ
Tanaka
A
A
Hall
F L
FL
Schreiber
S L
SL
D042846:CDC2-CDC28 Kinases; D002352:Carrier Proteins / Q000494:pharmacology*; D051357:Cyclin-Dependent Kinase 2; D018844:Cyclin-Dependent Kinases; D016213:Cyclins / Q000037:antagonists & inhibitors*; D016193:G1 Phase / Q000187:drug effects; D006360:Heat-Shock Proteins / Q000494:pharmacology*; D006801:Humans; D007166:Immunosuppressive Agents / Q000494:pharmacology*; D012516:Osteosarcoma; D011090:Polyenes / Q000494:pharmacology*; D006656:Protamine Kinase / Q000037:antagonists & inhibitors; D011485:Protein Binding; D047428:Protein Kinase Inhibitors; D017346:Protein Serine-Threonine Kinases; D016196:S Phase / Q000187:drug effects; D020123:Sirolimus; D022021:Tacrolimus Binding Proteins; D014407:Tumor Cells, Cultured
D002352:Carrier Proteins; D016213:Cyclins; D006360:Heat-Shock Proteins; D007166:Immunosuppressive Agents; D011090:Polyenes; D047428:Protein Kinase Inhibitors; D006656:Protamine Kinase; D017346:Protein Serine-Threonine Kinases; D042846:CDC2-CDC28 Kinases; C495894:CDK2 protein, human; D051357:Cyclin-Dependent Kinase 2; D018844:Cyclin-Dependent Kinases; D022021:Tacrolimus Binding Proteins; D020123:Sirolimus