Tyrosine phosphorylation modulates binding preference to cyclin-dependent kinases and subcellular localization of p27Kip1 in the acute promyelocytic leukemia cell line NB4.
We have investigated the role of tyrosine phosphorylation of the cyclin-dependent kinase (cdk) inhibitor p27Kip1 using the acute promyelocytic leukemia cell line NB4 together with granulocyte colony-stimulating factor (G-CSF). Short-term G-CSF stimulation resulted in a rapid tyrosine dephosphorylation of p27Kip1 accompanied by a change in its binding preferences to cdks. On G-CSF stimulation, p27Kip1 dissociated from cdk4 and associated with cdk2. Binding assays with recombinant p27Kip1 confirmed that tyrosine-phosphorylated p27Kip1 preferentially bound to cdk4, whereas unphosphorylated protein preferentially associated with cdk2. In addition, studies with p27Kip1 point mutations revealed a decisive role of Tyr88 and Tyr89 in binding to cdk4. Furthermore, phosphorylation of Tyr88 and Tyr89 was accompanied by strong nuclear translocation of p27Kip1. Taken together, this report provides the first evidence that tyrosine phosphorylation of p27Kip1 plays a crucial role in binding to cdks and its subcellular localization. Moreover, both effects are mediated by application of G-CSF.
Kardinal
Christian
C
Pädiatrische Hämatologie und Onkologie, Medizinische Hochschule Hannover (MHH), Hannover, Germany. kardinal.christian@mh-hannover.de
Dangers
Marc
M
Kardinal
Angelika
A
Koch
Alexandra
A
Brandt
Dominique Tobias
DT
Tamura
Teruko
T
Welte
Karl
K
D021581:Active Transport, Cell Nucleus / Q000187:drug effects; D045744:Cell Line, Tumor; D002467:Cell Nucleus / Q000378:metabolism*; D051357:Cyclin-Dependent Kinase 2 / Q000378:metabolism*; D051358:Cyclin-Dependent Kinase 4 / Q000378:metabolism*; D050760:Cyclin-Dependent Kinase Inhibitor p27 / Q000378:metabolism*; D016179:Granulocyte Colony-Stimulating Factor / Q000378:metabolism / Q000494:pharmacology*; D006801:Humans; D047908:Intracellular Signaling Peptides and Proteins / Q000378:metabolism*; D015473:Leukemia, Promyelocytic, Acute / Q000378:metabolism*; D010766:Phosphorylation; D011485:Protein Binding; D011499:Protein Processing, Post-Translational / Q000187:drug effects*; D014443:Tyrosine / Q000378:metabolism
C436291:CDKN1B protein, human; D047908:Intracellular Signaling Peptides and Proteins; D016179:Granulocyte Colony-Stimulating Factor; D050760:Cyclin-Dependent Kinase Inhibitor p27; D014443:Tyrosine; D051357:Cyclin-Dependent Kinase 2; D051358:Cyclin-Dependent Kinase 4