Elsevier

Developmental Biology

Volume 269, Issue 2, 15 May 2004, Pages 567-579
Developmental Biology

Involvement of Pax6 and Otx2 in the forebrain-specific regulation of the vertebrate homeobox gene ANF/Hesx1

https://doi.org/10.1016/j.ydbio.2004.01.044Get rights and content
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Abstract

During early vertebrate development, ANF homeobox genes are expressed in the prospective forebrain. Their regulation is essential for correct morphogenesis and function of the prosencephalon. We identified a 1-kb fragment upstream of the chicken GANF gene sufficient to drive lacZ expression in the endogenous expression domain. Concordant with the high conservation of this sequence in five investigated species, this element is also active in the corresponding expression domain of the zebrafish orthologue. In vivo analysis of two in vitro-identified Otx2 binding sites in this conserved sequence revealed their necessity for activation of the chicken ANF promoter. In addition, we identified a Pax6-binding site close to the transcriptional start site that is occupied in vivo by Pax6 protein. Pax6 and GANF exhibit mutually exclusive expression domains in the anterior embryonic region. Overexpression of Pax6 in chick embryos inhibited the endogenous GANF expression, and in Pax6−/− mice the expression domain of the murine ANF orthologue Hesx1 was expanded and sustained, indicating inhibitory effects of Pax6 on GANF. However, a mutation of the Pax6 site did not abolish reporter activity from an electroporated vector. We conclude that Otx2 and Pax6 are key molecules involved in conserved mechanisms of ANF gene regulation.

Keywords

Promoter
Transcription
Prosencephalon
DNA binding
Chick
Zebrafish
Mouse

Cited by (0)

1

These authors contributed equally to this work.

2

Present address: Westfälische Wilhelms-Universität Münster, Innere Medizin A/Hämatologie und Onkologie, Domagkstraße 3, 48129 Münster, Germany.

3

Present address: Max-Planck-Institut für Entwicklungsbiologie, Abteilung Genetik, Spemannstraße 35, 72076 Tübingen, Germany.