Putative role of CG3160 in morphogen secretion
Morphogens are secreted molecules that influence the fate of neighboring cells in a concentration-dependant manner. For this reason, their distribution and diffusion strongly influence their roles. In my master thesis, I focused on a posttranslational modification that might be involved in the diffusion of morphogens: GPI-anchoring. This mechanism links a target protein to a phosphatidylinositol via sugar moieties, thereby anchoring the protein to the cell membrane. To study the putative involvement of GPI-anchors in morphogen distribution, a gene implicated in the GPI-attachment process was used as a tool (CG3160). It was cloned and over expressed in cell culture and in flies to study the putative modification induced on morphogen diffusion. We found in cell culture that this over expression leads to an increased secretion of Wingless, a well-known morphogen in flies. In Vivo, wing imaginal disc were used to observe Wingless distribution when CG3160 is over expressed. No modification could be detected directly on this morphogen, but the activation of one of its target gene, sensless, was reduced. The results obtained are not sufficient to affirm that Wingless is a GPI-attached protein. Nevertheless, they show that CG3160 plays a role in Wg secretion, and that this role is important for sensless activation.