title: RhoGAP68F controls transport of adhesion proteins in Rab4 endosomes to modulate epithelial morphogenesis of Drosophila leg discs.
abstract: Elongation and invagination of epithelial tissues are fundamental developmental processes that contribute to the morphogenesis of embryonic and adult structures and are dependent on coordinated remodeling of cell-cell contacts. The morphogenesis of Drosophila leg imaginal discs depends on extensive remodeling of cell contacts and thus provides a useful system with which to investigate the underlying mechanisms. The small Rho GTPase regulator RhoGAP68F has been previously implicated in leg morphogenesis. It consists of on an N-terminal Sec14 domain and a C-terminal GAP domain. Here we examined the molecular function and role of RhoGAP68F in epithelial remodeling. We find that depletion of RhoGAP68F impairs epithelial remodeling from a pseudostratified to simple, while overexpression of RhoGAP68F causes tears of lateral cell-cell contacts and thus impairs epithelial integrity. We show that the RhoGAP68F protein localizes to Rab4 recycling endosomes and forms a complex with the Rab4 protein. The Sec14 domain is sufficient for localizing to Rab4 endosomes, while the activity of the GAP domain is dispensable. RhoGAP68F, in turn, inhibits the scission and movement of Rab4 endosomes involved in transport the adhesion proteins Fasciclin3 and E-cadherin back to cell-cell contacts. Expression of RhoGAP68F is upregulated during prepupal development suggesting that RhoGAP68F decreases the transport of key adhesion proteins to the cell surface during this developmental stage to decrease the strength of adhesive cell-cell contacts and thereby facilitate epithelial remodeling and leg morphogenesis.
authors.affiliation: Department of Developmental, Molecular and Chemical Biology, Program in Cell, Molecular and Developmental Biology, Program in Genetics, Sackler School of Graduate Biomedical Sciences, Tufts University School of Medicine, 150 Harrison Avenue, Boston, MA 02111, USA.
authors.forename: Beatriz Hernandez
authors.initials: BH
authors.lastname: de Madrid
authors.affiliation: Department of Developmental, Molecular and Chemical Biology, Program in Cell, Molecular and Developmental Biology, Program in Genetics, Sackler School of Graduate Biomedical Sciences, Tufts University School of Medicine, 150 Harrison Avenue, Boston, MA 02111, USA.
authors.forename: Lina
authors.initials: L
authors.lastname: Greenberg
authors.affiliation: Department of Developmental, Molecular and Chemical Biology, Program in Cell, Molecular and Developmental Biology, Program in Genetics, Sackler School of Graduate Biomedical Sciences, Tufts University School of Medicine, 150 Harrison Avenue, Boston, MA 02111, USA. Electronic address: victor.hatini@tufts.edu.
authors.forename: Victor
authors.initials: V
authors.lastname: Hatini
mesh_terms: D000818:Animals; D015820:Cadherins / Q000378:metabolism; D002448:Cell Adhesion / Q000235:genetics / Q000502:physiology; D015816:Cell Adhesion Molecules, Neuronal / Q000378:metabolism; D004330:Drosophila / Q000196:embryology*; D029721:Drosophila Proteins / Q000378:metabolism*; D011992:Endosomes / Q000502:physiology; D005121:Extremities / Q000196:embryology*; D005455:Fluorescent Antibody Technique; D020690:GTPase-Activating Proteins / Q000378:metabolism*; D060227:Imaginal Discs / Q000196:embryology*; D047468:Immunoprecipitation; D008164:Luminescent Proteins; D008954:Models, Biological; D009024:Morphogenesis / Q000502:physiology*; D021381:Protein Transport / Q000502:physiology; D034622:RNA Interference; D020695:rab4 GTP-Binding Proteins / Q000378:metabolism; D000097573:Red Fluorescent Protein
chemical_list: D015820:Cadherins; D015816:Cell Adhesion Molecules, Neuronal; D029721:Drosophila Proteins; D020690:GTPase-Activating Proteins; D008164:Luminescent Proteins; D020695:rab4 GTP-Binding Proteins; D000097573:Red Fluorescent Protein; C061565:Fas3 protein, Drosophila; C519487:RhoGAP68F protein, Drosophila
keywords: E-cadherin; Endocytic trafficking; Epithelial morphogenesis; Fasciclin3; Leg imaginal disc; Rab4; Rab5; Rab7; Rho GTPases; Tarsus