Inhibition of cell proliferation by the PCNA-binding region of p21 expressed as a GFP miniprotein.
p21 (WAF1/Cip1) is the only member of the CIP/KIP family which has a well-characterized PCNA-binding domain. p21 is known to have an important function in the coordination of the cellular pathways which are activated in response to DNA damage, though the significance of the p21-PCNA interaction is not completely clear. We have analyzed the effects of expressing a miniprotein containing the PCNA-binding domain of p21 upon the cell cycle and upon the proliferation of various cell types. We have compared this with the effect of expressing a mutant form which is defective in PCNA-binding, but which retains the secondary cyclin-CDK-inhibitory site. No PCNA-dependent effects were seen in the short term upon cell cycle distribution. However, clonogenic assays show that the GFP-peptide miniprotein can significantly suppress proliferation in a PCNA-dependent manner. In some cell types, however, the suppression of proliferation was not PCNA-dependent, suggesting that cellular environment is a contributory factor to the effect of this miniprotein. The capacity of this peptide sequence to suppress cell proliferation in vivo is of interest as the basis for the design of potential antiproliferative therapeutic agents.
Mattock
H
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Department of Surgery and Molecular Oncology, University of Dundee, Ninewells Hospital and Medical School, Dundee DD1 9SY, United Kingdom.
Lane
D P
DP
Warbrick
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E
D015153:Blotting, Western; D002455:Cell Division / Q000235:genetics / Q000502:physiology*; D050759:Cyclin-Dependent Kinase Inhibitor p21; D016213:Cyclins / Q000235:genetics / Q000378:metabolism*; D004791:Enzyme Inhibitors / Q000378:metabolism*; D005456:Fluorescent Dyes / Q000378:metabolism; D049452:Green Fluorescent Proteins; D006801:Humans; D008164:Luminescent Proteins / Q000235:genetics / Q000378:metabolism; D008856:Microscopy, Fluorescence; D010455:Peptides / Q000235:genetics / Q000378:metabolism*; D011233:Precipitin Tests; D018809:Proliferating Cell Nuclear Antigen / Q000235:genetics / Q000378:metabolism*; D017434:Protein Structure, Tertiary; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism; D014162:Transfection; D014407:Tumor Cells, Cultured; D014410:Tumor Stem Cell Assay
C493956:CDKN1A protein, human; D050759:Cyclin-Dependent Kinase Inhibitor p21; D016213:Cyclins; D004791:Enzyme Inhibitors; D005456:Fluorescent Dyes; D008164:Luminescent Proteins; D010455:Peptides; D018809:Proliferating Cell Nuclear Antigen; D011993:Recombinant Fusion Proteins; D049452:Green Fluorescent Proteins