Expression of a secreted form of Dally, a Drosophila glypican, induces overgrowth phenotype by affecting action range of Hedgehog

摘要: Glypicans, a family of heparan sulfate proteoglycans attached to the cell surface via glycosylphosphatidylinositol (GPI)-anchor, play essential roles in morphogen signaling and distributions. A Drosophila glypican, Dally, regulates gradient formation Decapentaplegic (Dpp) developing wing. To gain insights into function glypicans signaling, we examined activities two mutant forms Dally: transmembrane form (TM-Dally) secreted (Sec-Dally). Misexpression tm-dally wing disc had similar yet weaker effect enhancing Dpp compared that wild-type dally. In contrast, Sec-Dally shows weak dominant negative activity on signal transduction. Furthermore, sec-dally expression led patterning defects as well substantial overgrowth tissues animals through expansion action range Hh. These findings support recently proposed model have opposing and/or distinct effects from membrane-tethered forms.