| Abstract No.: | C-A3017 |
| Country: | Canada |
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| Title: | IS DYSTROGLYCAN REQUIRED TO ESTABLISH APICAL-BASAL POLARITY IN THE DROSOPHILA PHOTORECEPTORS? |
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| Authors/Affiliations: | 1 Nadia Melián*; 1 Salvatore Carbonetto;
1 Centre for Research in Neuroscience - McGill University, Montreal, QC, Canada
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| Content: | Objectives: The aim of this study is to determine if Dystroglcan (Dg) is required to establish photoreceptor apical-basal cell polarity in the developing Drosophila melanogaster retina. As the central component of the dystrophin glycoprotein complex (DGC), the cell surface receptor Dg links a cell’s cytoskeleton to its extracellular matrix. Disruption of the DGC results in muscular dystrophies. Dystroglycanopathies are a subset of muscular dystrophies, including Walker-Warburg syndrome and Muscle and Eye brain disease, which also central have nervous system defects linked to an inability of Dg to interact with the extra-cellular matrix. Dg is conserved in D. melanogaster and initial studies have demonstrated its requirement to establish both the anterior-posterior polarity and the epithelial polarity of the oocyte. The drosophila retina arises from a neuroepithelium where Dg may be required to establish apical-basal polarity. Understanding this may help contribute to our knowledge of Dg’s role in the CNS.
Materials and Methods: To test the hypothesis that in D. melanogaster Dg is required to establish photoreceptor apical-basal polarity, Dg deficient photoreceptors with be examined to determine if they correctly localise known polarity markers.
The Dg deficiency line used in this study, Dg248 a gift from Dr. Ruohola-Baker, was generated by the imprecise excision of a P-element in the Dg gene. Dg 248 homozygotes are embryonic and larval lethal prior to eye development. Dg deficient photoreceptors may therefore be generated using the FLP/FRT system. Flipase recombinase can be specifically driven early in the developing eye disc using the eyeless promoter. The resulting polarity state of Dg deficient photoreceptors will be examined during development when polarity is established.
Immunofluorescence and confocal analysis may be used to localise markers of apical-basal polarity in the developing Dg deficient photoreceptors. Apical markers include crumbs (stalk membrane), beta-catenin (adherens junction), and phalloidin (rhabdomere). A basal marker is the Na/K ATPase.
Results: Late stage Dg deficient pupae localise the photoreceptor polarity markers to the same subcellular locations as wild type photoreceptors. Dg deficient photoreceptors localise crumbs to the stalk membrane, beta-catenin to the adherens juncition and a high concentration of actin in the photoreceptor rhabdomere, indicates is apparent normal formation.
Conclusion: Preliminary results indicate that at late stage pupal development Dg deficient photoreceptors have established apical basal polarity. These data suggest that in D. melanogaster photoreceptors do not require Dg to establish their apical-basal polarity.
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