Dcdc42 acts in TGF-beta signaling during Drosophila morphogenesis: distinct roles for the Drac1/JNK and Dcdc42/TGF-beta cascades in cytoskeletal regulation

• Published in: Journal of cell science Vol. 112 ( Pt 8); no. 8; pp. 1225 - 1235
• Main Authors: Ricos, M G, Harden, N, Sem, K P, Lim, L, Chia, W
• Format: Journal Article
• Language: English
• Published: England 15-04-1999
• Subjects: Animals; Calcium-Calmodulin-Dependent Protein Kinases - physiology; Cytoskeleton - metabolism; Drosophila melanogaster - embryology; Drosophila melanogaster - genetics; Drosophila Proteins; Epidermis - metabolism; GTP-Binding Proteins - physiology; Immunohistochemistry; JNK Mitogen-Activated Protein Kinases; Microscopy, Confocal; Microscopy, Fluorescence; Mitogen-Activated Protein Kinases; Models, Genetic; Morphogenesis; Protein Serine-Threonine Kinases - metabolism; rac GTP-Binding Proteins; Receptors, Cell Surface - metabolism; Signal Transduction; Transforming Growth Factor beta - physiology; Transgenes
• ISSN: 0021-9533; 1477-9137
• DOI: 10.1242/jcs.112.8.1225

During Drosophila embryogenesis the two halves of the lateral epidermis migrate dorsally over a surface of flattened cells, the amnioserosa, and meet at the dorsal midline in order to form the continuous sheet of the larval epidermis. During this process of epithelial migration, known as dorsal closure, signaling from a Jun-amino-terminal-kinase cascade causes the production of the secreted transforming-growth-factor-beta-like ligand, Decapentaplegic. Binding of Decapentaplegic to the putative transforming-growth-factor-beta-like receptors Thickveins and Punt activates a transforming-growth-factor-beta-like pathway that is also required for dorsal closure. Mutations in genes involved in either the Jun-amino-terminal-kinase cascade or the transforming-growth-factor-beta-like signaling pathway can disrupt dorsal closure. Our findings show that although these pathways are linked they are not equivalent in function. Signaling by the Jun-amino-terminal-kinase cascade may be initiated by the small Ras-like GTPase Drac1 and acts to assemble the cytoskeleton and specify the identity of the first row of cells of the epidermis prior to the onset of dorsal closure. Signaling in the transforming-growth-factor-beta-like pathway is mediated by Dcdc42, and acts during the closure process to control the mechanics of the migration process, most likely via its putative effector kinase DPAK.