PPARalpha and AP-2alpha regulate bombesin receptor subtype 3 expression in ozone-stressed bronchial epithelial cells.

Abstract

Previously, we found that bombesin receptor subtype 3 (BRS-3) significantly increased in an ozone-stressed airway hyperresponsiveness animal model and resulted in induced wound repair and protection from acute lung injury. In the present study, we determined molecular mechanisms of BRS-3 regulation in human BECs (bronchial epithelial cells) in response to ozone stress. Ten oligonucleotide probes corresponding to various regions of the BRS-3 promoter were used in EMSA (electrophoretic mobilityshift assays). Four were found to have an enhanced mobility shift with extracts from ozone-stressed cells. On the basis of the assay of mutated probes binding with extracts and antibody supershift, they were verified as MTF-1 (metal-regulatory-element-binding transcription factor-1), PPARalpha (peroxisome-proliferator-activated receptor alpha), AP-2alpha (activator protein 2alpha) and HSF-1 (heat-shock factor 1). Next, ChIP (chromatin immunoprecipitation) assay, site-directed mutagenesis technology and antisense oligonucleotide technology were used to observe these transcription factors associated with the BRS-3 promoter. Only AP-2alpha and PPARalpha increased ozone-inducible DNA binding on the BRS-3 promoter and BRS-3 expression. The time courses of AP-2alpha and PPARalpha activation, followed by BRS-3 expression, were also examined. It was shown that ozone-inducible BRS-3 expression and AP-2alpha- and PPARalpha-binding activity correlated over a 48 h period. The translocation of PPARalpha was observed by immunofluorescence assay, which showed that PPARalpha nuclear translocation increased after ozone exposure. Our data suggest that AP-2alpha and PPARalpha may be especially involved in this ozone-inducible up-regulation mechanism of BRS-3 expression.

• Authors: Yu-rong Tan, Xiao-qun Qin, Yang Xiang, Tao Yang, Fei Qu, Yue Wang, Hui-jun Liu, H Christian Weber
• Journal: The Biochemical journal (Biochem J) Vol. 405 Issue 1 Pg. 131-7 (Jul 01 2007) ISSN: 1470-8728 [Electronic] England
• PMID: 17355223 (Publication Type: Journal Article, Research Support, Non-U.S. Gov't)

Chemical References

• Oxidants, Photochemical
• PPAR alpha
• Receptors, Bombesin
• Transcription Factor AP-2
• Transcription Factors
• bombesin receptor subtype 3
• Ozone

Topics

• Animals
• Base Sequence
• Bronchi (cytology)
• Cells, Cultured
• Epithelial Cells (drug effects, metabolism)
• Fibroblasts (cytology, physiology)
• Gene Expression Regulation
• Humans
• Molecular Sequence Data
• Mutagenesis, Site-Directed
• Oxidants, Photochemical (pharmacology)
• Ozone (pharmacology)
• PPAR alpha (genetics, metabolism)
• Promoter Regions, Genetic
• Receptors, Bombesin (genetics, metabolism)
• Transcription Factor AP-2 (genetics, metabolism)
• Transcription Factors (metabolism)
• Transcription, Genetic