c-myb transactivates cdc2 expression via Myb binding sites in the 5'-flanking region of the human cdc2 gene

J Biol Chem. 1993 Jan 25;268(3):2255-9.

Abstract

The c-myb protooncogene is preferentially expressed in hematopoietic cells and is required for cell cycle progression at the G1/S boundary. Because c-myb encodes a transcriptional activator that functions via DNA binding, it is likely that c-myb exerts its biological activity by regulating the transcription of genes required for DNA synthesis and cell cycle progression. One such gene, cdc2, encodes a 34-kDa serine-threonine kinase that appears to be required for G1/S transition in normal human T-lymphocytes. To determine whether c-myb is a transcriptional regulator of cdc2 expression, we subcloned a segment of a cdc2 human genomic clone containing extensive 5'-flanking sequences and part of the first exon. Sequence analysis revealed the presence of two closely spaced Myb binding sites that interact with bacterially synthesized Myb protein within a region extending from nucleotides -410 to -392 upstream of the transcription initiation site. A 465-base pair segment of 5'-flanking sequence containing these sites was linked to the CAT gene and had promoter activity in rodent fibroblasts. Cotransfection of this construct with a full-length human c-myb cDNA driven by the early simian virus 40 promoter resulted in a 6-8-fold enhancement of CAT activity that was abrogated by mutations in the Myb binding sites. These data suggest that c-myb participates in the regulation of cell cycle progression by activating the expression of the cdc2 gene.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Animals
  • Base Sequence
  • Binding Sites
  • CDC2 Protein Kinase / genetics*
  • Cell Line
  • Chloramphenicol O-Acetyltransferase / genetics
  • DNA / chemistry
  • DNA / genetics
  • DNA / metabolism*
  • Gene Expression*
  • Humans
  • Mice
  • Molecular Sequence Data
  • Mutagenesis
  • Polymerase Chain Reaction
  • Proto-Oncogene Proteins / genetics*
  • Proto-Oncogene Proteins / metabolism
  • Proto-Oncogene Proteins c-myb
  • RNA, Messenger / genetics
  • Recombinant Fusion Proteins / metabolism
  • Transcriptional Activation*
  • Transfection

Substances

  • Proto-Oncogene Proteins
  • Proto-Oncogene Proteins c-myb
  • RNA, Messenger
  • Recombinant Fusion Proteins
  • DNA
  • Chloramphenicol O-Acetyltransferase
  • CDC2 Protein Kinase

Associated data

  • GENBANK/L06298