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Transcription factor CP2 is essential for lens‐specific expression of the chicken αA‐crystallin gene
Author(s) -
Murata Takuya,
Nitta Masahiro,
Yasuda Kunio
Publication year - 1998
Publication title -
genes to cells
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.912
H-Index - 115
eISSN - 1365-2443
pISSN - 1356-9597
DOI - 10.1046/j.1365-2443.1998.00204.x
Subject(s) - biology , enhancer , transcription factor , crystallin , general transcription factor , microbiology and biotechnology , transcription (linguistics) , gene , e box , mutant , response element , promoter , taf2 , gene expression , genetics , linguistics , philosophy
Background: Lens‐specific transcriptional activation of the chicken αA‐crystallin gene is controlled by the distal and proximal enhancers, αCE1 and αCE2, respectively. Analysis using specific monoclonal antibodies against purified αCE1‐binding factor αCEF1 revealed that αCEF1 is composed of two distinct subunits. Results: We have demonstrated that one of the subunits of αCEF1 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 αCEF1 and bacterially expressed cCP2 form a tetramer. Overexpression of cCP2 activates transcription through αCE1, 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 α‐globin promoter, it fails to promote transcription through this template. Element substitution experiments between αCE1 and the CP2 template revealed that the lens‐specific enhancer activity of αCE1 is due to the 6 bp sequence (−139/−134; lens‐specific element (LSE)) adjacent to the 3′ of the cCP2 binding site within αCE1. Conclusion: We have shown that the tetrameric transcription factor cCP2 is essential for lens‐specific transcription of the chicken αA‐crystallin gene, although it is ubiquitously expressed. We propose a model where cCP2 cooperates with a putative lens‐specific factor which binds to LSE. Fig. 6.