Dpp signalling orchestrates dorsal closure by regulating cell shape changes both in the amnioserosa and in the epidermis.
During the final stages of embryogenesis, the Drosophila embryo exhibits a dorsal hole covered by a simple epithelium of large cells termed the amnioserosa (AS). Dorsal closure is the process whereby this hole is closed through the coordination of cellular activities within both the AS and the epidermis. Genetic analysis has shown that signalling through Jun N-terminal Kinase (JNK) and Decapentaplegic (Dpp), a Drosophila member of the BMP/TGF-beta family of secreted factors, controls these activities. JNK activates the expression of dpp in the dorsal-most epidermal cells, and subsequently Dpp acts as a secreted signal to control the elongation of lateral epidermis. Our analysis shows that Dpp function not only affects the epidermal cells, but also the AS. Embryos defective in Dpp signalling display defects in AS cell shape changes, specifically in the reduction of their apical surface areas, leading to defective AS contraction. Our data also demonstrate that Dpp regulates adhesion between epidermis and AS, and mediates expression of the transcription factor U-shaped in a gradient across both the AS and the epidermis. In summary, we show that Dpp plays a crucial role in coordinating the activity of the AS and its interactions with the LE cells during dorsal closure.
Fernández
Beatriz García
BG
Instituto Gulbenkian de Ciência, Rua da Quinta Grande 6, 2780-156 Oeiras, Portugal.
Arias
Alfonso Martinez
AM
Jacinto
Antonio
A
D000818:Animals; D019521:Body Patterning; D002448:Cell Adhesion; D048430:Cell Shape; D003599:Cytoskeleton / Q000378:metabolism; D029721:Drosophila Proteins / Q000378:metabolism*; D004331:Drosophila melanogaster / Q000166:cytology* / Q000196:embryology* / Q000201:enzymology; D004625:Embryo, Nonmammalian / Q000166:cytology; D000078404:Epidermal Cells; D004817:Epidermis / Q000196:embryology; D048031:JNK Mitogen-Activated Protein Kinases / Q000378:metabolism; D008954:Models, Biological; D009154:Mutation / Q000235:genetics; D009687:Nuclear Proteins / Q000378:metabolism; D009928:Organ Specificity; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism; D011956:Receptors, Cell Surface / Q000378:metabolism; D015398:Signal Transduction; D014157:Transcription Factors / Q000378:metabolism
D029721:Drosophila Proteins; D009687:Nuclear Proteins; D011956:Receptors, Cell Surface; D014157:Transcription Factors; C064196:dpp protein, Drosophila; C106513:peb protein, Drosophila; C109258:ush protein, Drosophila; C090169:tkv protein, Drosophila; D017346:Protein Serine-Threonine Kinases; D048031:JNK Mitogen-Activated Protein Kinases