Invasive cell behavior during Drosophila imaginal disc eversion is mediated by the JNK signaling cascade.
Drosophila imaginal discs are monolayered epithelial invaginations that grow during larval stages and evert at metamorphosis to assemble the adult exoskeleton. They consist of columnar cells, forming the imaginal epithelium, as well as squamous cells, which constitute the peripodial epithelium and stalk (PS). Here, we uncover a new morphogenetic/cellular mechanism for disc eversion. We show that imaginal discs evert by apposing their peripodial side to the larval epidermis and through the invasion of the larval epidermis by PS cells, which undergo a pseudo-epithelial-mesenchymal transition (PEMT). As a consequence, the PS/larval bilayer is perforated and the imaginal epithelia protrude, a process reminiscent of other developmental events, such as epithelial perforation in chordates. When eversion is completed, PS cells localize to the leading front, heading disc expansion. We found that the JNK pathway is necessary for PS/larval cells apposition, the PEMT, and the motile activity of leading front cells.
Pastor-Pareja
José Carlos
JC
Centro de Biología Molecular Severo Ochoa, CSIC-UAM, Cantoblanco, 28049 Madrid, Spain.
Grawe
Ferdinand
F
Martín-Blanco
Enrique
E
García-Bellido
Antonio
A
D000818:Animals; D019521:Body Patterning; D002455:Cell Division; D002460:Cell Line; D004330:Drosophila / Q000196:embryology*; D004331:Drosophila melanogaster / Q000378:metabolism; D004625:Embryo, Nonmammalian / Q000502:physiology; D004817:Epidermis / Q000196:embryology / Q000378:metabolism; D004848:Epithelium / Q000378:metabolism; D018507:Gene Expression Regulation, Developmental; D007150:Immunohistochemistry; D048031:JNK Mitogen-Activated Protein Kinases; D048670:MAP Kinase Kinase 4; D008648:Mesoderm / Q000378:metabolism; D008856:Microscopy, Fluorescence; D020929:Mitogen-Activated Protein Kinase Kinases / Q000502:physiology*; D008954:Models, Biological; D010641:Phenotype; D015398:Signal Transduction; D013997:Time Factors; D014921:Wings, Animal / Q000196:embryology*
D048031:JNK Mitogen-Activated Protein Kinases; D048670:MAP Kinase Kinase 4; D020929:Mitogen-Activated Protein Kinase Kinases