A complex enhancer of the chicken beta A3/A1-crystallin gene depends on an AP-1-CRE element for activity.
OBJECTIVE
To define transcriptional regulatory elements of the chicken beta A3/A1-crystallin gene.


METHODS
Reporter genes were made with fragments of the chicken beta A3/A1-crystallin gene fused to the bacterial gene encoding chloramphenicol acetyltransferase (CAT). The reporter plasmids were transfected into primary cultures of chicken-patched lens epithelium or fibroblast cells, and the CAT activity of cellular extracts was measured. The binding of lens nuclear proteins to beta A3/A1 sequences was tested in electrophoretic mobility shift assays.


RESULTS
Sequences from -287 to -254 bp relative to the transcriptional start site function as an enhancer in transfected lens and nonlens cells. The length of a T-rich sequence downstream of the enhancer influences its activity. Minimal enhancer activity depends on sequences between -270 and -254 bp, and full activity requires additional upstream sequences. The minimal enhancer includes a consensus sequence (TGAGTCA) for basic region-leucine zipper (bZIP) proteins of the AP-1-CREB superfamily. Lens nuclear proteins bind the enhancer sequences to form several specific complexes, some of which are related antigenically to members of the AP-1 and CREB families of proteins.


CONCLUSIONS
An enhancer of the chicken beta A3/A1-crystallin gene between -287 and -254 bp functions in both lens and nonlens cells and binds multiple nuclear proteins. Temporal and spatial regulation of beta A3/A1 expression in the lens may be regulated by the enhancer.
McDermott
J B
JB
Laboratory of Molecular and Developmental Biology, National Eye Institute, National Institutes of Health, Bethesda, Maryland 20892-2730, USA.
Cvekl
A
A
Piatigorsky
J
J
D000818:Animals; D002478:Cells, Cultured; D002642:Chick Embryo; D015500:Chloramphenicol O-Acetyltransferase / Q000378:metabolism; D003459:Crystallins / Q000235:genetics* / Q000378:metabolism; D017362:Cyclic AMP Response Element-Binding Protein / Q000235:genetics* / Q000378:metabolism; D017931:DNA Primers / Q000737:chemistry; D015342:DNA Probes / Q000737:chemistry; D004587:Electrophoresis, Agar Gel; D004848:Epithelium / Q000502:physiology; D005347:Fibroblasts / Q000502:physiology; D005809:Genes, Regulator / Q000235:genetics*; D017930:Genes, Reporter / Q000235:genetics; D007908:Lens, Crystalline / Q000502:physiology; D016350:Leucine Zippers / Q000235:genetics; D010957:Plasmids; D018808:Transcription Factor AP-1 / Q000235:genetics* / Q000378:metabolism; D014162:Transfection / Q000235:genetics
D003459:Crystallins; D017362:Cyclic AMP Response Element-Binding Protein; D017931:DNA Primers; D015342:DNA Probes; D018808:Transcription Factor AP-1; D015500:Chloramphenicol O-Acetyltransferase