Abstract
RING finger protein 43 (RNF43), an E3-type ubiquitin ligase, is frequently up-regulated in human colorectal cancer. It has been shown that expression of RNF43 is regulated by the Wnt-signaling pathway. However the regulatory region(s) for its transcriptional activation has not been clarified. In this study, we have shown for the first time that RNF43 is a direct target of TCF4/β-catenin complex, and that its expression is regulated by a regulatory region containing two Wnt-responsive elements (WREs) in intron2. A reporter gene assay revealed that nucleotide substitutions in the WREs decreased the reporter activity in colon cancer cells, suggesting that both WREs are involved in the transcriptional activation. Knockdown of β-catenin by siRNA suppressed the reporter activity. In addition, ChIP assay showed that both elements associate with TCF4/β-catenin complex in colon cancer cells. These data indicate that expression of RNF43 is regulated by the canonical Wnt/β-catenin pathway through binding of the WREs with TCF4/β-catenin complex. These findings should be useful for the understanding of the regulatory mechanism of RNF43 and may contribute to the clarification of signaling pathways regulated by RNF43.
Publication types
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Research Support, Non-U.S. Gov't
MeSH terms
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Basic Helix-Loop-Helix Leucine Zipper Transcription Factors / metabolism
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Cell Line, Tumor
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DNA-Binding Proteins / genetics*
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DNA-Binding Proteins / metabolism*
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Enhancer Elements, Genetic
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Gene Expression Regulation
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Gene Knockdown Techniques
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Gene Order
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Humans
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Introns*
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Oncogene Proteins / genetics*
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Oncogene Proteins / metabolism*
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Protein Binding
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Response Elements*
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Transcription Factor 4
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Transcription Factors / metabolism
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Ubiquitin-Protein Ligases
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Wnt Proteins / metabolism*
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beta Catenin / genetics
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beta Catenin / metabolism
Substances
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Basic Helix-Loop-Helix Leucine Zipper Transcription Factors
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DNA-Binding Proteins
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Oncogene Proteins
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TCF4 protein, human
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Transcription Factor 4
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Transcription Factors
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Wnt Proteins
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beta Catenin
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RNF43 protein, human
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Ubiquitin-Protein Ligases
Grants and funding
This work was supported in part by Grant-in-Aid for Scientific Research (#23310137), and Global COE Program “Center of education and research for the advanced genome-based medicine for personalized medicine and the control of worldwide infectious diseases”, from The Ministry of Education, Culture, Sports, Science and Technology (MEXT) Japan (
http://www.mext.go.jp/). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.