Drosophila wingless: A paradigm for the function and mechanism of Wnt signaling

Abstract

The link between oncogenesis and normal development is well illustrated by the study of the Wnt family of proteins. The first Wnt gene (int-1) was identified over a decade ago as a proto-oncogene, activated in response to proviral insertion of a mouse mammary tumor virus. Subsequently, the discovery that Drosophila wingless, a developmentally important gene, is homologous to int-1 supported the notion that int-1 may have a role in normal development. In the last few years it has been recognized that int-1 and Wingless belong to a large family of related glyco-proteins found in vertebrates and invertebrates. In recognition of this, members of this family have been renamed Wnts, an amalgam of int and Wingless. Investigation of Wnt genes in Xenopus and mouse indicates that Wnts have a role in cell proliferation, differentiation and body axis formation. Further analysis in Drosophila has revealed that Wingless function is required in several developmental processes in the embryo and imaginal discs. In addition, a genetic approach has identified some of the molecules required for the transmission and reception of the Wingless signal. We will review recent data which have contributed to our growing understanding of the function and mechanism of Drosophila Wingless signaling in cell fate determination, growth and specification of pattern.

Developmental roles of heparan sulfate proteoglycans in Drosophila

“…The homolog of vertebrate Wnt-1 is encoded by Drosophila Wg, which has been implicated as a mediator of positional information in a wide variety of developmental contexts. These include segmentation of the epidermis, patterning of the midgut epithelium, formation of the stomatogastric nervous system, neuroblast determination and differentiation and patterning of imaginal discs [22,23]. Wg can exert both shortand long-range effects during the development of the embryo and imaginal discs.…”

Delta is a ventral to dorsal signal complementary to Serrate, another Notch ligand, in Drosophila wing formation.

“…Candidates for the ventral to dorsal signal include wingless iwg), a member of the Wnt gene family, which encodes a secreted protein and is essential for wing deve]opment, as well as many other developmental processes in Drosophila Cfor review, see Klingensmith and Nusse 1994;Siegfried and Perrimon 1994). Loss-of-function wg mutations result in abnormal wing phenotypes, ranging from loss of wing margin bristles to complete absence of wing tissue, depending on the particular combination of alleles (Phillips and Whittle 1993; for review, see Lindsley and Zimm 1992).…”

Identification and Characterization of a Novel Line of Drosophila Schneider S2 Cells That Respond to Wingless Signaling

“…1-4) is a member of the Wnt gene family, which encodes a secreted glycoprotein involved in cell-cell signaling in a number of basic developmental processes in a wide range of animal phyla (5)(6)(7)(8). Genetic screening of Drosophila for mutations in segmental patterning has revealed several genes acting sequentially in the Wg signal transduction pathway (9). These genes are dishevelled (dsh, see Refs.…”