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.
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.
Cvekl
A
A
Laboratory of Molecular and Developmental Biology, National Eye Institute, National Institutes of Health, Bethesda, Maryland 20892-2730.
Sax
C M
CM
Bresnick
E H
EH
Piatigorsky
J
J
D000818:Animals; D001483:Base Sequence; D001665:Binding Sites / Q000235:genetics; D002478:Cells, Cultured; D002642:Chick Embryo; D002645:Chickens; D003459:Crystallins / Q000235:genetics*; D051786:Cyclic AMP Response Element Modulator; D017362:Cyclic AMP Response Element-Binding Protein / Q000378:metabolism; D004247:DNA / Q000235:genetics; D004268:DNA-Binding Proteins / Q000378:metabolism; D005136:Eye Proteins; D005786:Gene Expression Regulation; D018398:Homeodomain Proteins; D007908:Lens, Crystalline / Q000378:metabolism; D008957:Models, Genetic; D008969:Molecular Sequence Data; D016296:Mutagenesis; D000071841:PAX6 Transcription Factor; D051761:Paired Box Transcription Factors; D011401:Promoter Regions, Genetic; D012097:Repressor Proteins; D018808:Transcription Factor AP-1 / Q000378:metabolism; D014157:Transcription Factors / Q000378:metabolism*; D014162:Transfection; D051720:Upstream Stimulatory Factors
D003459:Crystallins; D017362:Cyclic AMP Response Element-Binding Protein; D004268:DNA-Binding Proteins; D005136:Eye Proteins; D018398:Homeodomain Proteins; D000071841:PAX6 Transcription Factor; D051761:Paired Box Transcription Factors; D012097:Repressor Proteins; D018808:Transcription Factor AP-1; D014157:Transcription Factors; D051720:Upstream Stimulatory Factors; D051786:Cyclic AMP Response Element Modulator; D004247:DNA