The cell cycle-regulated B-Myb transcription factor overcomes cyclin-dependent kinase inhibitory activity of p57(KIP2) by interacting with its cyclin-binding domain

J Biol Chem. 2003 Nov 7;278(45):44255-64. doi: 10.1074/jbc.M308953200. Epub 2003 Aug 28.

Abstract

The cell cycle-regulated B-Myb transcription factor is required for early embryonic development and is implicated in regulating cell growth and differentiation. In addition to its transcriptional regulatory properties, recent data indicate that B-Myb can release active cyclin/Cdk2 activity from the retinoblastoma-related p107 protein by directly interacting with the p107 N terminus. As this p107 domain has homology to the cyclin-binding domains of the p21(Waf1/Cip1) family of cyclin-dependent kinase inhibitors (CKIs), we investigated in this study whether B-Myb could also interact with these CKIs. No in vivo interaction was found with either p21(Waf1/Cip1) or p27(KIP1), however, binding to p57(KIP2) was readily detectable in both in vivo and in vitro assays. The B-Myb-interacting region of p57(KIP2) mapped to the cyclin-binding domain. Consistent with this, B-Myb competed with cyclin A2 for binding to p57(KIP2), resulting in release of active cyclin/Cdk2 kinase. Moreover, B-Myb partially overcame the ability of p57(KIP2) to induce G1 arrest in Saos-2 cells. Despite similarities with previous p107 studies, the B-Myb domains required for interaction with p57(KIP2) were quite different from those implicated for p107. Thus, it is evident that B-Myb may promote cell proliferation by a non-transcriptional mechanism that involves release of active cyclin/Cdk2 from p57(KIP2) as well as p107.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Amino Acid Sequence
  • Binding Sites
  • Binding, Competitive
  • Blotting, Western
  • CDC2-CDC28 Kinases / metabolism
  • Cell Cycle Proteins*
  • Cell Division
  • Cyclin A / metabolism
  • Cyclin A2
  • Cyclin-Dependent Kinase 2
  • Cyclin-Dependent Kinase Inhibitor p57
  • Cyclin-Dependent Kinases / antagonists & inhibitors*
  • Cyclins / metabolism*
  • DNA-Binding Proteins / chemistry
  • DNA-Binding Proteins / genetics
  • DNA-Binding Proteins / metabolism*
  • Enzyme Inhibitors / chemistry
  • Enzyme Inhibitors / metabolism
  • G1 Phase
  • Gene Deletion
  • Glutathione Transferase / genetics
  • Humans
  • Molecular Sequence Data
  • Mutagenesis, Site-Directed
  • Nuclear Proteins / chemistry*
  • Nuclear Proteins / genetics
  • Nuclear Proteins / metabolism*
  • Osteosarcoma
  • Peptide Fragments / chemistry
  • Peptide Fragments / metabolism
  • Recombinant Fusion Proteins
  • Retinoblastoma-Like Protein p107
  • Structure-Activity Relationship
  • Trans-Activators / chemistry
  • Trans-Activators / genetics
  • Trans-Activators / metabolism*
  • Transcriptional Activation
  • Tumor Cells, Cultured

Substances

  • CCNA2 protein, human
  • CDKN1C protein, human
  • Cell Cycle Proteins
  • Cyclin A
  • Cyclin A2
  • Cyclin-Dependent Kinase Inhibitor p57
  • Cyclins
  • DNA-Binding Proteins
  • Enzyme Inhibitors
  • MYBL2 protein, human
  • Nuclear Proteins
  • Peptide Fragments
  • RBL1 protein, human
  • Recombinant Fusion Proteins
  • Retinoblastoma-Like Protein p107
  • Trans-Activators
  • Glutathione Transferase
  • CDC2-CDC28 Kinases
  • CDK2 protein, human
  • Cyclin-Dependent Kinase 2
  • Cyclin-Dependent Kinases