Researcher(s)
- Domenica Moya, Biological Sciences, University of Delaware
Faculty Mentor(s)
- Erica Selva, Biological Sciences, University of Delaware
Abstract
The Wnt signaling pathway is a highly conserved and complex signaling network that controls essential cellular processes during normal development, tissue regeneration, and, when aberrant, can cause cancer. Wnt, the extracellular signaling ligand of the pathway, requires both Wntless (Wls) and Porcupine (Por) in the signal-sending cell to produce a fully mature Wnt ligand that is released to activate the pathway in receiving cells. Wls is the cargo protein required for the intracellular transport and secretion of Wnt proteins from signal-producing cells. Previous work in the Selva laboratory has shown that disulfide-bonded Wls homodimers are required for Wnt maturation and secretion. The objective of this summer project was to determine whether the two conserved disulfide bond forming cysteines within Wls are required for functional expression of the prototypical Drosophila Wnt, Wingless (Wg), in vivo. Using the UAS-GAL4 expression system, the ability of Wls C50A, C72A, and C50/72A mutants to rescue Wg secretion and adult viability in Drosophila wls homozygous mutant background was assessed. UAS-wls-V5 (wildtype), C50A, C72A, and C50/72A transgenic lines were crossed to a Hh-GAL4 driver line to drive their posterior compartment expression of developing wing discs, and Wg secretion was compared to the anterior compartment (no wls expression). Third-instar larval wing discs were analyzed by immunofluorescence using V5 and Wingless antibodies to assess transgene expression and Wg secretion. The preliminary findings suggest wls C50A, C72A, and C50/72A do not rescue Wg secretion, nor does its overexpression in a wls wildtype background result in any phenotypes. While the stocks with Wg-GAL4 to assess adult viability have not yet been completed, it is expected that the Wls disulfide bond mutants will not rescue to adulthood. These findings indicate the cysteine residues within Wls are required for Wls function and provide further insight into the structural requirements underlying Wnt ligand maturation.