Lens-specific enhancer in the third intron regulates expression of the chicken delta 1-crystallin gene.
We have previously shown that the tissue specificity determinant of the chicken delta 1-crystallin gene lies 3' of position -100 (Hayashi et al. 1985). Since the promoter of the gene (delta 1-crystallin promoter) did not show any tissue specificity, we examined various segments of the delta 1-crystallin gene for a tissue-specific enhancer activity by placing each segment downstream of a heterologous transcriptional unit coding for chloramphenicol acetyltransferase (CAT) and by transfecting chicken tissues in primary culture. We found that a segment spanning the third intron bears a strong lens-specific enhancer activity. This "delta 1-crystallin enhancer" activates transcription from the delta 1-crystallin promoter 20- to 40-fold in lens cells and to various degrees with other promoters. Deletion analysis of the enhancer region indicated that it covered nearly 1 kb but did not indicate clear-cut boundaries. For its enhancer effect the core region of 120 bp and associations with certain adjoining regions were required. Removal of the enhancer from the gene totally abolished delta 1-crystallin expression, and reinsertion of the enhancer in either upstream, internal, or downstream positions restored expression. We conclude that the delta 1-crystallin enhancer is an essential and major determinant for lens-specificity of delta 1-crystallin expression.
Hayashi
S
S
Department of Biophysics, Faculty of Science, Kyoto University, Japan.
Goto
K
K
Okada
T S
TS
Kondoh
H
H
D000818:Animals; D001483:Base Sequence; D002478:Cells, Cultured; D002642:Chick Embryo; D003459:Crystallins / Q000235:genetics*; D004262:DNA Restriction Enzymes; D004742:Enhancer Elements, Genetic; D005786:Gene Expression Regulation; D005796:Genes; D007438:Introns; D007908:Lens, Crystalline / Q000378:metabolism*; D008969:Molecular Sequence Data; D010957:Plasmids; D014158:Transcription, Genetic
D003459:Crystallins; D004262:DNA Restriction Enzymes