A complex array of positive and negative elements regulates the chicken alpha A-crystallin gene: involvement of Pax-6, USF, CREB and/or CREM, and AP-1 proteins

Mol Cell Biol. 1994 Nov;14(11):7363-76. doi: 10.1128/mcb.14.11.7363-7376.1994.

Abstract

The abundance of crystallins (> 80% of the soluble protein) in the ocular lens provides advantageous markers for selective gene expression during cellular differentiation. Here we show by functional and protein-DNA binding experiments that the chicken alpha A-crystallin gene is regulated by at least five control elements located at sites A (-148 to -139), B (-138 to -132), C (-128 to -101), D (-102 to -93), and E (-56 to -41). Factors interacting with these sites were characterized immunologically and by gel mobility shift experiments. The results are interpreted with the following model. Site A binds USF and is part of a composite element with site B. Site B binds CREB and/or CREM to enhance expression in the lens and binds an AP-1 complex including CREB, Fra2 and/or JunD which interacts with USF on site A to repress expression in fibroblasts. Sites C and E (which is conserved across species) bind Pax-6 in the lens to stimulate alpha A-crystallin promoter activity. These experiments provide the first direct data that Pax-6 contributes to the lens-specific expression of a crystallin gene. Site D (-104 to -93) binds USF and is a negative element. Thus, the data indicate that USF, CREB and/or CREM (or AP-1 factors), and Pax-6 bind a complex array of positive and negative cis-acting elements of the chicken alpha A-crystallin gene to control high expression in the lens and repression in fibroblasts.

MeSH terms

  • Animals
  • Base Sequence
  • Binding Sites / genetics
  • Cells, Cultured
  • Chick Embryo
  • Chickens
  • Crystallins / genetics*
  • Cyclic AMP Response Element Modulator
  • Cyclic AMP Response Element-Binding Protein / metabolism
  • DNA / genetics
  • DNA-Binding Proteins / metabolism
  • Eye Proteins
  • Gene Expression Regulation
  • Homeodomain Proteins*
  • Lens, Crystalline / metabolism
  • Models, Genetic
  • Molecular Sequence Data
  • Mutagenesis
  • PAX6 Transcription Factor
  • Paired Box Transcription Factors
  • Promoter Regions, Genetic
  • Repressor Proteins*
  • Transcription Factor AP-1 / metabolism
  • Transcription Factors / metabolism*
  • Transfection
  • Upstream Stimulatory Factors

Substances

  • Crystallins
  • Cyclic AMP Response Element-Binding Protein
  • DNA-Binding Proteins
  • Eye Proteins
  • Homeodomain Proteins
  • PAX6 Transcription Factor
  • Paired Box Transcription Factors
  • Repressor Proteins
  • Transcription Factor AP-1
  • Transcription Factors
  • Upstream Stimulatory Factors
  • Cyclic AMP Response Element Modulator
  • DNA