Department of Integrative Biology, University of Basel, Rheinsprung 9, CH-4051 Basel, Switzerland,
We are studying the molecular mechanisms underlying brain development. Here we report on the role of the regulatory control gene wingless in embryonic brain development of Drosophila.
Wingless is a secreted signaling molecule of the segment polarity gene class which is known to be involved in many processes during Drosophila development. For example, during segmentation it helps to define the parasegmental and segmental boundaries; later in development it is involved in the patterning of imaginal discs (see Siegfried and Perrimon, 1994).
In vertebrates several wingless related genes - the Wnt genes - have been found, some of which are expressed in the developing vertebrate brain. Four genes of the Wnt family are expressed at the midbrain-hindbrain boundary (Wnt-1, Wnt-3, Wnt-5a, Wnt-7b). Wnt-3 expression also extends into the diencephalon (see Puelles and Rubenstein, 1993).
Is a similar expression pattern of wingless found in the developing insect brain? In this report we use high resolution molecular neuroanatomical techniques to show that wingless is indeed expressed in the developing Drosophila brain in a complex spatio-temporal pattern. We further demonstrate that mutational inactivation of wingless results in distinct and striking defects in the developing fly brain.
We conclude that wingless is required for the development of a specific brain region in Drosophila. Thus, the regionalized expression of its Wnt homologs in vertebrate brains is an indication of highly conserved genetic regulatory mechanisms for brain patterning.
Puelles and Rubenstein (1993) TINS 16:472-479; Siegfried and Perrimon (1994) BioEssays 16:395-404
(Supported by the SNSF)