Cyclin D1 is a nuclear protein required for cell cycle progression in G1.
A cascade of events is triggered upon the addition of growth factor to quiescent mammalian cells, which ultimately restarts proliferation by inducing the transition from G0/G1 to S-phase. We have studied cyclin D1, a putative G1 cyclin, in normal diploid human fibroblasts. Cyclin D1 accumulated and reached a maximum level before S-phase upon the addition of serum to quiescent cells. The protein was localized to the nucleus, and it disappeared from the nucleus as cells proceeded into S-phase. Microinjection of anti-cyclin D1 antibodies or antisense plasmid prevented cells from entering S-phase, and the kinetics of inhibition showed that cyclin D1 is required at a point in the cell cycle earlier than cyclin A. These results demonstrate that cyclin D1 is a critical target of proliferative signals in G1.
Differentiation Programme, European Molecular Biology Laboratory, Heidelberg, Germany.
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Baldin
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Lukas
M J
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Marcote
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Pagano
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Draetta
D016375:Antisense Elements (Genetics); D015153:Blotting, Western; D002460:Cell Line; D002467:Cell Nucleus / Q000378:metabolism; D019938:Cyclin D1; D016213:Cyclins / Q000378:metabolism / Q000502:physiology*; D004247:DNA / Q000096:biosynthesis; D005347:Fibroblasts / Q000166:cytology; D005455:Fluorescent Antibody Technique; D016193:G1 Phase / Q000502:physiology*; D006801:Humans; D008168:Lung / Q000166:cytology / Q000502:physiology / Q000648:ultrastructure; D008845:Microinjections; D015513:Oncogene Proteins / Q000378:metabolism / Q000502:physiology*; D010957:Plasmids; D016196:S Phase / Q000502:physiology*; D013997:Time Factors
D016375:Antisense Elements (Genetics); D016213:Cyclins; D015513:Oncogene Proteins; D019938:Cyclin D1; D004247:DNA