Transcription factor CP2 is essential for lens-specific expression of the chicken alphaA-crystallin gene

Genes Cells. 1998 Jul;3(7):443-57. doi: 10.1046/j.1365-2443.1998.00204.x.


Background: Lens-specific transcriptional activation of the chicken alphaA-crystallin gene is controlled by the distal and proximal enhancers, alphaCE1 and alphaCE2, respectively. Analysis using specific monoclonal antibodies against purified alphaCE1-binding factor alphaCEF1 revealed that alphaCEF1 is composed of two distinct subunits.

Results: We have demonstrated that one of the subunits of alphaCEF1 is encoded by chicken ubiquitous transcription factor CP2 (cCP2), which is homologous to mouse CP2, and human CP2/LBP-1/LSF-1. Electrophoretic mobility shift assays and cross-linking experiments showed that alphaCEF1 and bacterially expressed cCP2 form a tetramer. Overexpression of cCP2 activates transcription through alphaCE1, but a mutant cCP2 lacking the DNA-binding domain reduced the transcription to basal levels. Although cCP2 binds to the CP2 template from the mouse alpha-globin promoter, it fails to promote transcription through this template. Element substitution experiments between alphaCE1 and the CP2 template revealed that the lens-specific enhancer activity of alphaCE1 is due to the 6 bp sequence (-139/-134; lens-specific element (LSE)) adjacent to the 3' of the cCP2 binding site within alphaCE1.

Conclusion: We have shown that the tetrameric transcription factor cCP2 is essential for lens-specific transcription of the chicken alphaA-crystallin gene, although it is ubiquitously expressed. We propose a model where cCP2 cooperates with a putative lens-specific factor which binds to LSE.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Amino Acid Sequence
  • Animals
  • Base Sequence
  • Cell Nucleus / chemistry
  • Chick Embryo
  • Chickens
  • Cloning, Molecular
  • Crystallins / genetics*
  • DNA / metabolism
  • DNA-Binding Proteins / chemistry
  • DNA-Binding Proteins / genetics
  • DNA-Binding Proteins / metabolism*
  • Enhancer Elements, Genetic / genetics
  • Lens, Crystalline / metabolism*
  • Mice
  • Molecular Sequence Data
  • Molecular Weight
  • Organ Specificity
  • Protein Conformation
  • RNA, Messenger / analysis
  • RNA-Binding Proteins
  • Recombinant Fusion Proteins
  • Sequence Analysis, DNA
  • Transcription Factors / chemistry
  • Transcription Factors / genetics
  • Transcription Factors / metabolism*
  • Transcription, Genetic / genetics
  • Transcriptional Activation / genetics*


  • Crystallins
  • DNA-Binding Proteins
  • RNA, Messenger
  • RNA-Binding Proteins
  • Recombinant Fusion Proteins
  • TFCP2 protein, human
  • Tfcp2 protein, mouse
  • Transcription Factors
  • DNA

Associated data

  • GENBANK/AB004542