Identification of transcription factors regulating CTNNAL1 expression in human bronchial epithelial cells

PLoS One. 2012;7(2):e31158. doi: 10.1371/journal.pone.0031158. Epub 2012 Feb 16.

Abstract

Adhesion molecules play important roles in airway hyperresponsiveness or airway inflammation. Our previous study indicated catenin alpha-like 1 (CTNNAL1), an alpha-catenin-related protein, was downregulated in asthma patients and animal model. In this study, we observed that the expression of CTNNAL1 was increased in lung tissue of the ozone-stressed Balb/c mice model and in acute ozone stressed human bronchial epithelial cells (HBEC). In order to identify the possible DNA-binding proteins regulating the transcription of CTNNAL1 gene in HBEC, we designed 8 oligo- nucleotide probes corresponding to various regions of the CTNNAL1 promoter in electrophoretic mobility shift assays (EMSA). We detected 5 putative transcription factors binding sites within CTNNAL1 promoter region that can recruit LEF-1, AP-2α and CREB respectively by EMSA and antibody supershift assay. Chromatin immunoprecipitation (ChIP) assay verified that AP-2 α and LEF-1 could be recruited to the CTNNAL1 promoter. Therefore we further analyzed the functions of putative AP-2 and LEF-1 sites within CTNNAL1 promoter by site-directed mutagenesis of those sites within pGL3/FR/luc. We observed a reduction in human CTNNAL1 promoter activity of mutants of both AP-2α and LEF-1 sites. Pre-treatment with ASOs targeting LEF-1and AP-2α yielded significant reduction of ozone-stress-induced CTNNAL1 expression. The activation of AP-2α and LEF-1, followed by CTNNAL1 expression, showed a correlation during a 16-hour time course. Our data suggest that a robust transcriptional CTNNAL1 up-regulation occurs during acute ozone-induced stress and is mediated at least in part by ozone-induced recruitments of LEF-1 and AP-2α to the human CTNNAL1 promoter.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Binding Sites
  • Bronchi / cytology*
  • DNA-Binding Proteins
  • Epithelial Cells / metabolism*
  • Gene Expression Regulation*
  • Humans
  • Lymphoid Enhancer-Binding Factor 1 / genetics
  • Lymphoid Enhancer-Binding Factor 1 / metabolism*
  • Mice
  • Ozone / pharmacology
  • Promoter Regions, Genetic
  • Stress, Physiological / genetics
  • Transcription Factor AP-2 / genetics
  • Transcription Factor AP-2 / metabolism*
  • Transcription Factors / physiology*
  • alpha Catenin / genetics*

Substances

  • CTNNAL1 protein, human
  • DNA-Binding Proteins
  • Lymphoid Enhancer-Binding Factor 1
  • Transcription Factor AP-2
  • Transcription Factors
  • alpha Catenin
  • Ozone