The New Role Of Hedgehog And Dpp Signaling Pathways In The Drosophila Wing Development

Cell survival,cell growth,morphogenesis and patterning is the fundamental processes involved in the normal life activities.Hhedghog(Hh)and Decapentaplegic(Dpp)signalling are involved in most of these developmental processes.However,the role of Hh in cell survival and Dpp in morphogenesis has no detailed research.In this thesis,we carried out the research on cell survival and morphogenesis regulated by Hh and Dpp,respectively.The following conclusions are obtained:1.Hh signaling is essential for the cell survival in the central region of Drosophia wing disc.There's massive apoptosis within the wing pouch when Hh was reduced from the transcriptional level,the transportation level and the signal transduction level.The cell death is independent of Dpp signaling and Jun N-terminal Kinase(JNK)signalling.The proapoptotic gene hid was activated while the survival factor was inhibited when Hh signaling was downregulated.The apoptosis and reduction of adult wing size were rescued when diapl was coexpressed in the pouch region.2.Dorsocross(Doc),a member of Tbx6 family,was identified as the target gene of Dpp signalling.Dpp-Doc signaling is required for the thorax closure in Drosophila.Doc is specifically expressed in the leading edge cells in notum.Doc expression was diminished or inhibited when the receptor Thincvein(Tkv)was downregulated or the signalling inhibitor Daughter against Dpp(Dad)was overexpressed,respectively.There's obvious thorax closure defect when Doc was inhibited in the notum region.The cytoskeleton,such as DE-cadherin(DE-Cad),Disc large(Dlg),Tubulin,participated in the thorax closure process.The correct dynamic changes of these molecular is important for the thorax closure.The thorax closure defect was rescued whencadherin was coexpressed with tkvDN or Doc3RNAi in the Drosophila notum.What's more,there's a parallel relationship between Dpp-Doc and JNK signalling in regulating the thorax closure.3.Doc is essential for the fate transition of lateral neuron from epithelium.Ectopic Ac was expressed when Doc was overexpressed,which is independent of Notch-Wingless(Wg)signaling.A transcriptional repressor factor Groucho(Gro)is inhibited to derepress Achaete/Scute Complex(AS-C)expression by overexpressing Doc2.Other members of Tbx familily,such as Tbx2,is required for the cell fate transition due to the activation of Wg signaling.4.A preliminary analysis of Doc downstream target gene was carried out.Expression Profile was analyzed when Doc was overexpressed or inhibited in the whole wing disc.Due to the wing disc overexpressed Doc,there're 1118 up-regulated genes and 85 down-regulated genes.Due to the wing disc downregulated Doc,there're 22 up-regulated genes and 51 down-regulated genes.These results is essential for the following research to reveal the function of Doc and the mechanism.All the above experiments show the related genes and pathways involved the biological principal,which is essential for studying agricultural insect's wing development and providing the candidate target genes in controlling migrating insect using genetics methods.