RESUMO
To achieve a highly differentiated state, cells undergo multiple transcriptional processes whose coordination and timing are not well understood. In Drosophila embryonic epidermal cells, polished-rice (Pri) smORF peptides act as temporal mediators of ecdysone to activate a transcriptional program leading to cell shape remodeling. Here, we show that the ecdysone/Pri axis concomitantly represses the transcription of a large subset of cuticle genes to ensure proper differentiation of the insect exoskeleton. The repression relies on the transcription factor Ken and persists for several days throughout early larval stages, during which a soft cuticle allows larval crawling. The onset of these cuticle genes normally awaits the end of larval stages when the rigid pupal case assembles, and their premature expression triggers abnormal sclerotization of the larval cuticle. These results uncovered a temporal switch to set up distinct structures of cuticles adapted to the animal lifestyle and which might be involved in the evolutionary history of insects.
Assuntos
Proteínas de Drosophila , Ecdisona , Animais , Ecdisona/metabolismo , Drosophila/genética , Drosophila/metabolismo , Diferenciação Celular/genética , Fatores de Transcrição/genética , Fatores de Transcrição/metabolismo , Peptídeos/metabolismo , Larva/genética , Insetos/genética , Regulação da Expressão Gênica no Desenvolvimento , Proteínas de Drosophila/genética , Proteínas de Drosophila/metabolismoRESUMO
The terminal differentiation of epithelial cells involves changes in the apical compartment, including remodeling of the cytoskeleton and junctions to modify its three-dimensional organization. It also often triggers the building of specialized extracellular matrices, the function of which remains poorly understood. Hundreds of extracellular matrix proteins expressed in a variety of epithelia possess a conserved region called the zona pellucida-domain (ZP domain). There is evidence to suggest that ZP-domains mediate the polymerization of proteins into fibrils or matrices and that mutation of ZP-domains can result in severe pathologies, such as infertility, deafness, and cancer. Recent work in worms and flies demonstrates that ZP-domain proteins play a crucial role in organizing and shaping highly specialized apical structures in epithelial cells.
Assuntos
Células Epiteliais/citologia , Células Epiteliais/metabolismo , Proteínas da Matriz Extracelular/química , Proteínas da Matriz Extracelular/metabolismo , Matriz Extracelular/química , Matriz Extracelular/metabolismo , Junções Intercelulares , Estrutura Terciária de Proteína , Zona Pelúcida/química , Zona Pelúcida/metabolismoRESUMO
The zona pellucida domain (ZPD) defines a conserved family of membrane-anchored matrix proteins that are, as yet, poorly characterized with respect to their functions during development. Using genetic approaches in flies, we show here that a set of eight ZPD proteins is required for the localized reorganization of embryonic epidermal cells during morphogenesis. Despite varying degrees of sequence conservation, these ZPD proteins exert specific and nonredundant functions in the remodeling of epidermal cell shape. Each one accumulates in a restricted subregion of the apical compartment, where it organizes local interactions between the membrane and the extracellular matrix. In addition, ZPD proteins are required to sculpture the actin-rich cell extensions and maintain appropriate organization of the apical compartment. These results on ZPD proteins therefore reveal a functional subcompartmentalization of the apical membrane and its role in the polarized control of epithelial cell shape during development.