Document Detail

The mechanism of recruitment of the lactate dehydrogenase-B/epsilon-crystallin gene by the duck lens.
MedLine Citation:
PMID:  8876643     Owner:  NLM     Status:  MEDLINE    
In duck, the housekeeping enzyme lactate dehydrogenase B (LDH-B) and the lens structural protein epsilon-crystallin are encoded by the same single copy gene. Transcription of the gene is initiated from two closely spaced start sites, at -28 and +1. The usage of the downstream site is greatly enhanced in lens. Deletion mapping of the promoter shows that the region -70/+18 specifies the enhanced promoter activity in the lens. A critical role is played by the consensus Sp1 binding site at -50; mutation of this site abolishes lens-preferred expression. Deletion of the +1 transcription initiation site also leads to a decrease in lens-preferred expression, which can be restored by moving the -28 transcription initiation site downstream. By band shift experiments, supershift mobility assays and methylation interference assays, Sp1 was shown to bind to the Sp1 consensus binding site at -50 using either heart or lens nuclear extracts. Co-expression of Sp1 or Sp1-like factors inhibited the activity of an LDH-B/epsilon-crystallin promoter construct by approximately 60% in lens and by 40% in heart cells. Co-expression of Pax-6, a transcription factor shown to be involved in the lens-enhanced expression of a number of other crystallin genes, did not influence the promoter activity of the -130/+650 LDH-B/epsilon-crystallin promoter construct. In contrast to other crystallin promoters, the LDH-B/epsilon-crystallin promoter does not appear to contain a lens-specific element, rather our data lead to a model in which a factor transmitting the effect of Sp1, bound at -50, to the transcription initiation complex is responsible for the lens-preferred expression of the LDH-B/epsilon-crystallin promoter.
G A Brunekreef; H J Kraft; J G Schoenmakers; N H Lubsen
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't    
Journal Detail:
Title:  Journal of molecular biology     Volume:  262     ISSN:  0022-2836     ISO Abbreviation:  J. Mol. Biol.     Publication Date:  1996 Oct 
Date Detail:
Created Date:  1996-11-22     Completed Date:  1996-11-22     Revised Date:  2008-11-21    
Medline Journal Info:
Nlm Unique ID:  2985088R     Medline TA:  J Mol Biol     Country:  ENGLAND    
Other Details:
Languages:  eng     Pagination:  629-39     Citation Subset:  IM    
Department of Molecular Biology and Cell Biology, University of Nijmegen, The Netherlands.
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MeSH Terms
Cells, Cultured
Crystallins / genetics*
DNA Footprinting
DNA-Binding Proteins / physiology*
Ducks / genetics*
Eye Proteins
Gene Expression Regulation, Developmental
Homeodomain Proteins*
L-Lactate Dehydrogenase / genetics*
Lens, Crystalline / physiology*
Paired Box Transcription Factors
Promoter Regions, Genetic
Regulatory Sequences, Nucleic Acid
Repressor Proteins
Sp1 Transcription Factor / physiology*
Transcription, Genetic
Reg. No./Substance:
0/Crystallins; 0/DNA-Binding Proteins; 0/Eye Proteins; 0/Homeodomain Proteins; 0/Isoenzymes; 0/PAX6 protein; 0/Paired Box Transcription Factors; 0/Repressor Proteins; 0/Sp1 Transcription Factor; EC Dehydrogenase

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