CCAAT/enhancer binding protein epsilon is preferentially up-regulated during granulocytic differentiation and its functional versatility is determined by alternative use of promoters and differential splicing

Proc Natl Acad Sci U S A. 1997 Jun 10;94(12):6462-7. doi: 10.1073/pnas.94.12.6462.

Abstract

CCAAT/enhancer binding protein (C/EBP) epsilon is a recently cloned member of the C/EBP family of transcription factors and is expressed exclusively in cells of hematopoietic origin. The human C/EBPepsilon gene is transcribed by two alternative promoters, Palpha and Pbeta. A combination of differential splicing and alternative use of promoters generates four mRNA isoforms, of 2.6 kb and 1.3-1.5 kb in size. These transcripts can encode three proteins of calculated molecular mass 32.2 kDa, 27.8 kDa, and 14.3 kDa. Accordingly, Western blots with antibodies specific for the DNA-binding domain, that is common to all forms, identify multiple proteins. C/EBPepsilon mRNA was greatly induced during in vitro granulocytic differentiation of human primary CD34(+) cells. Retinoic acid treatment of HL60 promyelocytic leukemia cells for 24 hr induced C/EBPepsilon mRNA levels by 4-fold, while prolonged treatment gradually reduced mRNA expression to pretreatment levels. Transient transfection experiments with expression vectors for two of the isoforms demonstrated that the 32.2-kDa protein is an activator of transcription of granulocyte colony-stimulating factor receptor promoter, while the 14.3-kDa protein is not. Thus, C/EBPepsilon is regulated in a complex fashion and may play a role in the regulation of genes involved in myeloid differentiation.

Publication types

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

MeSH terms

  • Alternative Splicing*
  • Amino Acid Sequence
  • Animals
  • Base Sequence
  • CCAAT-Enhancer-Binding Proteins*
  • Cell Differentiation
  • Cell Line
  • Cloning, Molecular
  • DNA Primers
  • Exons
  • Granulocytes / cytology
  • Granulocytes / physiology*
  • HeLa Cells
  • Humans
  • Leucine Zippers
  • Mice
  • Molecular Sequence Data
  • Monocytes / physiology
  • Neutrophils / physiology
  • Polymerase Chain Reaction
  • Promoter Regions, Genetic*
  • RNA, Messenger / biosynthesis
  • Recombinant Proteins / biosynthesis
  • Recombinant Proteins / chemistry
  • Sequence Alignment
  • Sequence Homology, Amino Acid
  • Transcription Factors / biosynthesis*
  • Transcription Factors / chemistry
  • Transcription Factors / genetics
  • Transfection

Substances

  • CCAAT-Enhancer-Binding Proteins
  • Cebpe protein, mouse
  • DNA Primers
  • RNA, Messenger
  • Recombinant Proteins
  • Transcription Factors
  • CEBPE protein, human