WINGLESS AND DWNT4, 2 DROSOPHILA WNT GENES HAVE RELATED EXPRESSION, REGULATION AND FUNCTION DURING THE EMBRYONIC-DEVELOPMENT

The multigenic Wnt family encode secreted signalling molecules with im portant regulatory functions in various developmental processes. This paper reports an analysis of the relationships, in terms of structure, expression and function, that exist between the Drosophila genes wing less, the orthologue of the mammalian Wnt1 proto-oncogene, and DWnt4, a new member of the Wnt family. The 2 genes are physically clustered, are transcribed in overlapping embryonic territories under the control of the same regulatory molecules. Go-expression and co-regulation sug gest first, that the close physical linkage results from the sharing o f cis-control elements and second that the 2 Wnt signals cooperate in developmental patterning events. Antisense RNA experiments revealed th at signalling by DWnt4 is essential for cells from the anterior compar tment of each parasegment to adopt a denticled fate. We propose that w ingless and DWnt4 achieve opposite, but complementary functions in int rasegmental cell patterning of the embryonic ectoderm.