p12(DOC-1) is a novel cyclin-dependent kinase 2-associated protein.
Regulated cyclin-dependent kinase (CDK) levels and activities are critical for the proper progression of the cell division cycle. p12(DOC-1) is a growth suppressor isolated from normal keratinocytes. We report that p12(DOC-1) associates with CDK2. More specifically, p12(DOC-1) associates with the monomeric nonphosphorylated form of CDK2 (p33CDK2). Ectopic expression of p12(DOC-1) resulted in decreased cellular CDK2 and reduced CDK2-associated kinase activities and was accompanied by a shift in the cell cycle positions of p12(DOC-1) transfectants ( upward arrow G(1) and downward arrow S). The p12(DOC-1)-mediated decrease of CDK2 was prevented if the p12(DOC-1) transfectants were grown in the presence of the proteosome inhibitor clasto-lactacystin beta-lactone, suggesting that p12(DOC-1) may target CDK2 for proteolysis. A CDK2 binding mutant was created and was found to revert p12(DOC-1)-mediated, CDK2-associated cell cycle phenotypes. These data support p12(DOC-1) as a specific CDK2-associated protein that negatively regulates CDK2 activities by sequestering the monomeric pool of CDK2 and/or targets CDK2 for proteolysis, reducing the active pool of CDK2.
Shintani
S
S
Laboratory of Molecular Pathology, Medical School, Harvard University, Boston, Massachusetts 02115, USA.
Ohyama
H
H
Zhang
X
X
McBride
J
J
Matsuo
K
K
Tsuji
T
T
Hu
M G
MG
Hu
G
G
Kohno
Y
Y
Lerman
M
M
Todd
R
R
Wong
D T
DT
D015153:Blotting, Western; D042846:CDC2-CDC28 Kinases; D002453:Cell Cycle; D002455:Cell Division; D002460:Cell Line; D002850:Chromatography, Gel; D051357:Cyclin-Dependent Kinase 2; D018844:Cyclin-Dependent Kinases / Q000378:metabolism*; D015853:Cysteine Proteinase Inhibitors / Q000494:pharmacology; D006801:Humans; D015603:Keratinocytes / Q000378:metabolism; D007783:Lactones / Q000494:pharmacology; D008168:Lung / Q000378:metabolism; D016297:Mutagenesis, Site-Directed; D010641:Phenotype; D010766:Phosphorylation; D011485:Protein Binding; D014176:Protein Biosynthesis; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism*; D011506:Proteins / Q000235:genetics / Q000378:metabolism*; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D013997:Time Factors; D014018:Tissue Distribution; D014162:Transfection; D025521:Tumor Suppressor Proteins
C096151:CDK2AP1 protein, human; D015853:Cysteine Proteinase Inhibitors; D007783:Lactones; D011506:Proteins; D011993:Recombinant Fusion Proteins; D025521:Tumor Suppressor Proteins; C098869:clasto-lactacystin beta-lactone; D017346:Protein Serine-Threonine Kinases; D042846:CDC2-CDC28 Kinases; C495894:CDK2 protein, human; D051357:Cyclin-Dependent Kinase 2; D018844:Cyclin-Dependent Kinases