title: Rescue of defective mitogenic signaling by D-type cyclins.
abstract: Three gene products, including Myc and the D- and E-type G1 cyclins, are rate limiting for G1 progression in mammalian fibroblasts. Quiescent mouse NIH 3T3 fibroblasts engineered to express a mutant colony-stimulating factor (CSF-1) receptor (CSF-1R 809F) fail to synthesize c-myc and cyclin D1 mRNAs upon CSF-1 stimulation and remain arrested in early G1 phase. Ectopic expression of c-myc or either of three D-type cyclin genes, but not cyclin E, resensitized these cells to the mitogenic effects of CSF-1, enabling them to proliferate continuously in liquid culture and to form colonies in agar in response to the growth factor. Rescue by cyclin D1 was enhanced by c-myc but not by cyclin E and was reversed by infecting cyclin D1-reconstituted cells with a retroviral vector encoding catalytically inactive cyclin-dependent kinase 4. Induction of cyclin D1 mRNA by CSF-1 was restored in cells forced to express c-myc, and vice versa, suggesting that expression of the two genes is interdependent. Cells reconstituted with c-myc were prevented from entering S phase when microinjected with a monoclonal antibody to cyclin D1, and conversely, those rescued by cyclin D1 were inhibited from forming CSF-1-dependent colonies when challenged with a dominant-negative c-myc mutant. Cyclin D mutants defective in binding to the retinoblastoma protein were impaired in rescuing mitogenic signaling. Therefore, Myc and D-type cyclins collaborate during the mitogenic response to CSF-1, whereas cyclin E functions in a separate pathway.
authors.affiliation: Department of Tumor Cell Biology, St. Jude Children's Research Hospital, Memphis, TN 38105, USA.
authors.forename: M F
authors.initials: MF
authors.lastname: Roussel
authors.forename: A M
authors.initials: AM
authors.lastname: Theodoras
authors.forename: M
authors.initials: M
authors.lastname: Pagano
authors.forename: C J
authors.initials: CJ
authors.lastname: Sherr
mesh_terms: D016475:3T3 Cells; D000818:Animals; D019938:Cyclin D1; D056742:Cyclin D2; D016213:Cyclins / Q000235:genetics / Q000378:metabolism*; D016193:G1 Phase / Q000235:genetics / Q000502:physiology; D007399:Interphase / Q000235:genetics / Q000502:physiology*; D016173:Macrophage Colony-Stimulating Factor / Q000378:metabolism*; D051379:Mice; D008845:Microinjections; D015513:Oncogene Proteins / Q000235:genetics / Q000378:metabolism; D016271:Proto-Oncogene Proteins c-myc / Q000235:genetics / Q000378:metabolism; D012333:RNA, Messenger / Q000032:analysis; D016186:Receptor, Macrophage Colony-Stimulating Factor / Q000172:deficiency* / Q000378:metabolism; D016160:Retinoblastoma Protein / Q000378:metabolism; D016196:S Phase / Q000235:genetics / Q000502:physiology; D015398:Signal Transduction / Q000235:genetics / Q000502:physiology*
chemical_list: C486196:Ccnd2 protein, mouse; D056742:Cyclin D2; D016213:Cyclins; D015513:Oncogene Proteins; D016271:Proto-Oncogene Proteins c-myc; D012333:RNA, Messenger; D016160:Retinoblastoma Protein; D019938:Cyclin D1; D016173:Macrophage Colony-Stimulating Factor; D016186:Receptor, Macrophage Colony-Stimulating Factor