Document Detail

Control of the tissue inhibitor of metalloproteinases-1 promoter in culture-activated rat hepatic stellate cells: regulation by activator protein-1 DNA binding proteins.
MedLine Citation:
PMID:  10051488     Owner:  NLM     Status:  MEDLINE    
In the injured liver hepatic stellate cells (HSCs) undergo a dramatic phenotypic transformation known as "activation" in which they become myofibroblast-like and express high levels of the tissue inhibitor of metalloproteinase 1 (TIMP-1). HSC activation is accompanied by transactivation of the TIMP-1 promoter. Truncation mutagenesis studies delineated a minimal active promoter consisting of nucleotides -102 to +60 relative to the major start site for transcription. Removal of an AP-1 site located at nucleotides -93 to -87 caused almost a complete loss of promoter activity. Analysis of AP-1 DNA binding activities during culture activation of HSCs initially indicated transient expression of proteins capable of forming a low mobility AP-1 DNA binding complex (LMAP-1). LMAP-1 was maximally induced at 24 hours of culture and then fell to undetectable levels at 120 hours. Western blot studies showed that both c-Fos and c-Jun underwent similar transient inductions. These temporal changes in c-Fos and c-Jun activities were unexpected because TIMP-1 mRNA expression is not detected in HSCs until culture day 3 to 5 and is thereafter sustained at a high level. Previous work in other cell lineages has established a key role for Pea3 binding proteins (Ets-1) in AP-1 mediated transactivation of the TIMP-1 promoter. We show that HSCs express relatively low levels Ets-1 and Ets-2 and show that mutagenesis of the Pea3 DNA binding site in the TIMP-1 promoter has less than a twofold effect on its activity in activated HSCs. Further analysis of AP-1 DNA binding activities in 7- to 14-day culture activated HSCs led to the discovery of high mobility AP-1 complexes (HMAP-1). HMAP-1 DNA binding activities were sequence specific with respect to AP-1 and absent from freshly isolated HSCs. Supershift EMSA and Western blot studies identified JunD, Fra2, and FosB as potential components of the HMAP-1. Mutations of the AP-1 site of the TIMP-1 promoter that prevented formation of HMAP-1 caused a 70% loss of activity in transfected activated HSCs. Taken together the data indicate that sustained upregulation of TIMP-1 gene expression may be at least partially controlled by a novel AP-1 dependent regulation of TIMP-1 promoter activity.
M J Bahr; K J Vincent; M J Arthur; A V Fowler; D E Smart; M C Wright; I M Clark; R C Benyon; J P Iredale; D A Mann
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't    
Journal Detail:
Title:  Hepatology (Baltimore, Md.)     Volume:  29     ISSN:  0270-9139     ISO Abbreviation:  Hepatology     Publication Date:  1999 Mar 
Date Detail:
Created Date:  1999-03-29     Completed Date:  1999-03-29     Revised Date:  2009-09-29    
Medline Journal Info:
Nlm Unique ID:  8302946     Medline TA:  Hepatology     Country:  UNITED STATES    
Other Details:
Languages:  eng     Pagination:  839-48     Citation Subset:  IM    
University Medicine, Southampton General Hospital, Southampton, UK.
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MeSH Terms
Base Sequence
Binding Sites / physiology
Cells, Cultured
DNA / metabolism
DNA-Binding Proteins / metabolism,  physiology*
Liver / cytology,  metabolism,  physiology*
Molecular Sequence Data
Mutation / physiology
Promoter Regions, Genetic / physiology*
Protein Processing, Post-Translational / physiology
Proto-Oncogene Proteins c-fos / metabolism
Proto-Oncogene Proteins c-jun / metabolism
Rats, Sprague-Dawley
Tissue Inhibitor of Metalloproteinase-1 / genetics*
Transcription Factor AP-1 / physiology*
Transcription Factors / metabolism
Transcriptional Activation / physiology
Grant Support
//Wellcome Trust
Reg. No./Substance:
0/DNA-Binding Proteins; 0/Etv5 protein, rat; 0/Proto-Oncogene Proteins c-fos; 0/Proto-Oncogene Proteins c-jun; 0/Tissue Inhibitor of Metalloproteinase-1; 0/Transcription Factor AP-1; 0/Transcription Factors; 0/transcription factor PEA3; 9007-49-2/DNA

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine

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