Crossregulation between En-2 and Wnt-1 in chick tectal development

Authors

  • Sayaka Sugiyama,

    Corresponding author
    1. Department of Molecular Neurobiology, Institute of Development, Aging and Cancer, Tohoku University, Aoba-ku, Sendai 980-8575, Japan.
    2. Biological Institute, Graduate School of Science, Tohoku University, Aoba-ku, Sendai 980-8575, Japan.
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  • Jun-ichi Funahashi,

    1. Department of Molecular Neurobiology, Institute of Development, Aging and Cancer, Tohoku University, Aoba-ku, Sendai 980-8575, Japan.
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  • Jan Kitajewski,

    1. Department of Pathology, Columbia University Medical Center, 630W 168th St, New York, NY 10032, USA.
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  • Harukazu Nakamura

    1. Department of Pathology, Columbia University Medical Center, 630W 168th St, New York, NY 10032, USA.
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* Author to whom all correspondence should be addressed.

Abstract

En-1, En-2 and Wnt-1 are proposed to be essential signals for the development of the optic tectum in chick embryos. Drosophila engrailed and wingless, homologs of En (En-1 and En-2) and Wnt-1, respectively, have been shown to crossregulate each other. In the present paper, it is reported that crossregulation between En-2 and Wnt-1 is preserved in the development of the chick optic tectum. When En-2 is overexpressed by the replication competent retroviral vector, Wnt-1 is expressed ectopically at the dorsal midline of the diencephalon. When Wnt-1 is introduced extrinsically either by ectopic transplantation of mesencephalon, or by implantation of Wnt-1 producing cells, En-2 is induced ectopically at the dorsal midline of the tel-diencephalic border. Thus, ectopic expression of En-2 and Wnt-1 leads to crossregulation of each other in the chick brain. As diencephalon transdifferentiates into the optic tectum by an appropriate signal, the crossregulation of En-2 and Wnt-1 in the diencephalon may mimic the relationship required for early development in the tectum.

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