title: Distinct Rap1 activity states control the extent of epithelial invagination via α-catenin.
abstract: Localized cell shape change initiates epithelial folding, while neighboring cell invagination determines the final depth of an epithelial fold. The mechanism that controls the extent of invagination remains unknown. During Drosophila gastrulation, a higher number of cells undergo invagination to form the deep posterior dorsal fold, whereas far fewer cells become incorporated into the initially very similar anterior dorsal fold. We find that a decrease in α-catenin activity causes the anterior fold to invaginate as extensively as the posterior fold. In contrast, constitutive activation of the small GTPase Rap1 restricts invagination of both dorsal folds in an α-catenin-dependent manner. Rap1 activity appears spatially modulated by Rapgap1, whose expression levels are high in the cells that flank the posterior fold but low in the anterior fold. We propose a model whereby distinct activity states of Rap1 modulate α-catenin-dependent coupling between junctions and actin to control the extent of epithelial invagination.
authors.affiliation: Department of Molecular Biology, Howard Hughes Medical Institute, Princeton University, Princeton, NJ 08544, USA.
authors.forename: Yu-Chiun
authors.initials: YC
authors.lastname: Wang
authors.forename: Zia
authors.initials: Z
authors.lastname: Khan
authors.forename: Eric F
authors.initials: EF
authors.lastname: Wieschaus
mesh_terms: D000199:Actins / Q000378:metabolism; D000818:Animals; D002448:Cell Adhesion; D015815:Cell Adhesion Molecules / Q000378:metabolism*; D002462:Cell Membrane / Q000378:metabolism; D048430:Cell Shape; D004330:Drosophila / Q000166:cytology / Q000201:enzymology* / Q000235:genetics; D029721:Drosophila Proteins / Q000378:metabolism*; D004625:Embryo, Nonmammalian / Q000166:cytology / Q000201:enzymology / Q000378:metabolism; D004789:Enzyme Activation; D004847:Epithelial Cells / Q000166:cytology* / Q000201:enzymology; D020558:GTP Phosphohydrolases / Q000378:metabolism*; D020690:GTPase-Activating Proteins / Q000378:metabolism*; D017344:Genes, Insect; D049452:Green Fluorescent Proteins / Q000378:metabolism; D007365:Intercellular Junctions / Q000378:metabolism; D034622:RNA Interference; D013997:Time Factors; D059008:Time-Lapse Imaging; D051178:alpha Catenin / Q000378:metabolism*
chemical_list: D000199:Actins; D015815:Cell Adhesion Molecules; D029721:Drosophila Proteins; D020690:GTPase-Activating Proteins; C109224:Rapgap1 protein, Drosophila; D051178:alpha Catenin; C081439:alpha-Cat protein, Drosophila; D049452:Green Fluorescent Proteins; D020558:GTP Phosphohydrolases