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Open Access Research article

Human teneurin-1 is a direct target of the homeobox transcription factor EMX2 at a novel alternate promoter

Jan Beckmann12, Antonio Vitobello12, Jacqueline Ferralli1, Daniela Kenzelmann Brož3, Filippo M Rijli12 and Ruth Chiquet-Ehrismann12*

Author affiliations

1 Friedrich Miescher Institute for Biomedical Research, Novartis Research Foundation, Maulbeerstrasse 66, CH-4058 Basel, Switzerland

2 University of Basel, Faculty of Science, Basel, Switzerland

3 Current Address: Department of Radiation Oncology, Division of Radiation and Cancer Biology, Stanford University School of Medicine, Stanford, CA 94305, USA

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Citation and License

BMC Developmental Biology 2011, 11:35  doi:10.1186/1471-213X-11-35

Published: 8 June 2011

Abstract

Background

Teneurin-1 is a member of a family of type II transmembrane proteins conserved from C.elegans to vertebrates. Teneurin expression in vertebrates is best studied in mouse and chicken, where the four members teneurin-1 to -4 are predominantly expressed in the developing nervous system in area specific patterns. Based on their distinct, complementary expression a possible function in the establishment of proper connectivity in the brain was postulated. However, the transcription factors contributing to these distinctive expression patterns are largely unknown. Emx2 is a homeobox transcription factor, known to be important for area specification in the developing cortex. A study of Emx2 knock-out mice suggested a role of Emx2 in regulating patterned teneurin expression.

Results

5'RACE of human teneurin-1 revealed new alternative untranslated exons that are conserved in mouse and chicken. Closer analysis of the conserved region around the newly identified transcription start revealed promoter activity that was induced by EMX2. Mutation of a predicted homeobox binding site decreased the promoter activity in different reporter assays in vitro and in vivo in electroporated chick embryos. We show direct in vivo binding of EMX2 to the newly identified promoter element and finally confirm that the endogenous alternate transcript is specifically upregulated by EMX2.

Conclusions

We found that human teneurin-1 is directly regulated by EMX2 at a newly identified and conserved promoter region upstream of the published transcription start site, establishing teneurin-1 as the first human EMX2 target gene. We identify and characterize the EMX2 dependent promoter element of human teneurin-1.