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Emx1 and Emx2 Show Different Patterns of Expression During Proliferation and Differentiation of the Developing Cerebral Cortex in the Mouse

Authors

  • Massimo Gulisano,

    1. DIBIT, Istituto Scientifico H. S. Raffaele, Via Olgettina 60, 20132 Milano, Italy
    2. Istituto di Biologia Generale, Via Androne 81, 95124 Catania, Italy
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  • Vania Broccoli,

    1. DIBIT, Istituto Scientifico H. S. Raffaele, Via Olgettina 60, 20132 Milano, Italy
    2. Istituto di Genetica, Dipartimento di Biologia Evoluzionistica Sperimentale, Via Belmeloro 8, 40126 Bologna, Italy
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  • Celia Pardini,

    1. DIBIT, Istituto Scientifico H. S. Raffaele, Via Olgettina 60, 20132 Milano, Italy
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  • Edoardo Boncinelli

    Corresponding author
    1. DIBIT, Istituto Scientifico H. S. Raffaele, Via Olgettina 60, 20132 Milano, Italy
    2. Centro Infrastrutture Cellulari, Via Vanvitelli 32, 20129 Milano, Italy
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Edoardo Boncinelli, DIBIT, Istituto Scientifico H. S. Raffaele, Via Olgettina 60, 20132 Milano, Italy

Abstract

Insights into the complex structure of the forebrain and its regulation have recently come from the analysis of the expression of genes that are likely to be involved in regionalization of this structure. We cloned four new homeo box genes, Emx1, Emx2, Otx1 and Otx2, and we showed that in day 10 mouse embryos their expression domains are continuous regions of the developing brain contained within each other in the sequence Emx1 < Emx2 < Otx1 < Otx2. Recently Otx1 has been found to be specifically expressed during neurogenesis of layers 5 and 6 in the developing cerebral cortex. In order to better understand the role of Emx1 and Emx2 in the maturation of the cortex we analysed by in situ hybridization their expression patterns in the developing mouse cerebral cortex, from embryonic day 12.5 to adulthood. We found that Emx2 is expressed exclusively in proliferating cells of the ventricular zone whereas Emx1 is expressed in both proliferating and differentiated neurons, throughout the cortical layers and during all the developmental stages examined. Therefore, Emx2 gene products might control some biological parameters of the proliferation of cortical neuroblasts or of the subsequent cell migration of postmitotic neurons, leaving the cortical germinal zone. Conversely, Emx1 expression, which is confined exclusively to the dorsal telencephalon, characterizes most cortical neurons during proliferation, differentiation, migration and postnatal development and maturation.

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