v-Abl protein-tyrosine kinase up-regulates p21WAF-1 in cell cycle arrested and proliferating myeloid cells.
v-Abl protein-tyrosine kinase (PTK) promotes cell survival without cell proliferation in interleukin (IL)-3-deprived IC.DP premast cells (1). We now show that in these conditions v-Abl PTK transcriptionally up-regulated the cyclin-dependent kinase inhibitor (CDKI) p21(WAF-1) and inhibited CDK2 and CDK4. When readdition of IL-3 stimulated cell proliferation, p21(WAF-1) was inactivated as a CDKI despite maintenance of elevated protein level. p21(WAF-1) was also up-regulated yet was nonfunctional as a CDKI when v-Abl PTK was activated in cells maintained in IL-3, but this occurred without increased p21(WAF-1) transcription. Using a C-terminal epitope-specific p21(WAF-1) antibody, v-Abl PTK-mediated increase in p21(WAF-1) could be detected in intact cells only in the presence of IL-3. This indicated different binding partners of p21(WAF-1) and/or protein conformation in nondividing or proliferating cells, respectively. The binding of CDK2, CDK4, or proliferating cell nuclear antigen to p21(WAF-1) and its subcellular localization were unchanged in the presence or absence of IL-3. However, two-dimensional analysis revealed different forms of up-regulated p21(WAF-1) in IL-3-deprived, nondividing cells compared with IL-3-stimulated proliferating cells. These data demonstrate that elevation of the CDKI p21(WAF-1) is not always sufficient for cell cycle arrest and indicate an IL-3-sensitive pathway for the inactivation of p21(WAF-1) function as a CDKI.
Khanna
S J
SJ
Cancer Research Campaign Molecular Pharmacology Group, School of Biological Sciences, University of Manchester, G38 Stopford Building, Oxford Road, Manchester M13 9PT, United Kingdom.
Brown
R
R
Whetton
A D
AD
Ball
K L
KL
Dive
C
C
D000818:Animals; D002453:Cell Cycle / Q000502:physiology; D002455:Cell Division / Q000502:physiology; D002460:Cell Line; D050759:Cyclin-Dependent Kinase Inhibitor p21; D016213:Cyclins / Q000502:physiology*; D016313:Genes, abl / Q000502:physiology*; D008407:Mast Cells / Q000166:cytology* / Q000502:physiology*; D051379:Mice; D009154:Mutation; D015398:Signal Transduction / Q000502:physiology*; D015854:Up-Regulation
C493957:Cdkn1a protein, mouse; D050759:Cyclin-Dependent Kinase Inhibitor p21; D016213:Cyclins