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Suppression of collagenase gene expression by all‐trans and 9‐cis retinoic acid is ligand dependent and requires both RARs and RXRs
Author(s) -
Pan Luying,
Eckhoff Christian,
Brinckerhoff Constance E.
Publication year - 1995
Publication title -
journal of cellular biochemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.028
H-Index - 165
eISSN - 1097-4644
pISSN - 0730-2312
DOI - 10.1002/jcb.240570402
Subject(s) - retinoic acid , retinoid x receptor , gene expression , retinoid , microbiology and biotechnology , biology , collagenase , retinoic acid receptor , extracellular matrix , regulation of gene expression , chemistry , nuclear receptor , biochemistry , gene , transcription factor , enzyme
Abstract Retinoic acids (RA) are active metabolites of vitamin A which affect the expression of many genes involved in embryonic development, cell differentiation, and homeostasis. One important target gene for RA is matrix metalloproteinase (MMP‐1, collagenase), the only enzyme active at neutral pH that can degrade interstitial collagen, a major component of extracellular matrix. Using a cell line of normal rabbit synovial fibroblasts, HIG82 cells, as a model, we report that both all‐trans‐ and 9‐cis‐RA inhibit collagenase synthesis. This inhition occurs at a transcriptional level and is ligand‐dependent. Constitutive levels of retinoic acid receptor (RAR) mRNA levels are low, but are increased by all‐trans and by 9‐cis RA. In contrast, consitutive levels of retinoid X receptor (RXR) mRNA are higher and are not affected by RA. To measure DNA/protein interactions, we used a gel mobility shift assay with oligonucleotides containing either an AP‐1 site or a 40 bp region between −182/ −141, nuclear extracts from RT‐treated cells, and antibodies to RARs and RXRs. We found that both RARs and RXRs interact with these regions of the collagenase promoter, perhaps as part of a complex with other proteins. Our results suggest that heterodimers between RARs and RXRs mediate suppression of the collagenase gene by RA, and that RAR is a limiting factor in this negative regulation.