The actin cytoskeleton and RhoGTPases in Drosophila photoreceptor morphogenesis
Abstract
Rhodopsin is essential for photoreceptor morphogenesis; photoreceptors lacking rhodopsin degenerate in humans, mice and Drosophila. The mechanism of this requirement is not known. Here we report that transgenic expression of a dominant-active Drosophila Rho GTPase, Drac1, rescues photoreceptor morphogenesis in rhodopsin-null mutants; expression of dominant-negative Drac1 results in a phenotype similar to that seen in rhodopsin null mutants. Drac1 immunolocalizes to a specialization of the photoreceptor cortical actin cytoskeleton; this specialization is lost in rhodopsin null mutants. These results suggest that rhodopsin organizes the actin cytoskeleton via Drac1, contributing a structural support essential for photoreceptor morphogenesis. Adherens junctions formation between photoreceptors is essential for preventing cell death. I report that expression of dominant negative Cdc42N17 results in a failure of adherens junctions formation and retinal degeneration, a phenotype similar to D-APC loss and Armadillo overexpression. Cdc42 immunolocalizes to the photoreceptor actin cytoskeleton of adherens junctions. These results suggest a role for CDC42 in integrating photoreceptor physical adhesion with cell survival through Armadillo.
Degree
Ph.D.
Advisors
Ready, Purdue University.
Subject Area
Cellular biology
Off-Campus Purdue Users:
To access this dissertation, please log in to our
proxy server.