Effects Of Ectopic Dichaete Expression On Imaginal Discs Of Drosophila

The SOX family are transcriptional factors.This protein family shares highly conserved DNA binding domains known as HMG?High-mobility group?box domains containing approximately 80 amino acids^[1-2].SRY?sex determining region Y?-box 2,also known as SOX2,is a transcription factor that is essential for maintaining self-renewal,or pluripotency,of undifferentiated embryonic stem cells.Sox2 has a critical role in maintenance of embryonic and neural stem cells^[3-5].Decreasing the expression of SOX inhibits cell cycle.However,overexpression of SOX2promotes cell cycle.At the same time,SOX2 maybe necessary for the continuous proliferation of tumor cells^[6-7].Drosophila is very similar to humans in terms of organ development and configuration regulation mechanisms.Research using Drosophila as a research model can provide important reference for human disease treatment^[8].Drosophila wing is an important research object for developmental biology.Because of its clear signal for developmental regulation and high differentiation ability,it is an ideal model for studying tumor cell type proliferation and developmental plasticity.The Drosophila Dichaete gene is highly homologous to the mammalian SOX2 gene.This study focused on effect of ectopic expression of Dichaete in imaginal disc.The main contents are as follows:1.Effect of ectopic Dichaete expression on leg of DrosophilaEctopic Dichaete expression caused legs tarsus shortened.The leg disc in the larval state and the leg disc in the early pupal stage are normal in morphology.Increased Dll expression could affect the development of the leg distal structure.Ectopic Dichaete expression interferes with maintenance of distal-less gene,leading to structural defects of adult leg of Drosophila melanogaster.2.Effect of ectopic Dichaete expression on wing of DrosophilaThe results showed that the ectopic Dichaete expression had different effects on different regions of wing disc.In the wing pouch:ectopic Dichaete expression in wing disc,a certain degree of apoptosis was detected in wing pouch.Detection of morphogen Wg showed that ectopic Dichaete expression in the wing pouch inhibits Wg signal.Consequently,wing vein appear to be merged.Detection of downstream Vg signals is also suppressed.Vg plays a direct role in the formation of the wings.The down-regulation of Vg caused by the down-regulation of Wg signal.In notum,ectopic Dichaete expression leads to notum specific over-proliferation.Continuous ectopic Dichaete expression could respecify cell fate in the notum.A new wing has formed in adult thoracoabdominal dorsal plate.The ectopic Dichaete could increase Wingless signal in notum.Upstream signal of Notch is enhanced on proliferative region of notum by ectopic Dichaete.Therefore,the ectopic expression of Dichaete induces a new wing pouch in notum via Notch/Wg pathyway.3.Ectopic expression of Dichaete on Drosophila wing disc can induce stem cell characteristicsSOX2 meybe associated with maintaining self-renewal^[9].Stem cells have the ability to re-differentiate.Ectopic expression of Dichaete on wing disc can form a new winglet in adult notum.We hypothesized that it may be related to induction and re-differentiation of ips cells.Then,we detect the stem cell-related and cell redifferentiation markers:Vasa,SXL,Bam,E-cad^[10].Vasa and SXL are important marker genes in the early stage of stem cells.In the wild type,the expression of both genes is low.The Vasa and SXL expression in DPP>Dichaete wing disc of 3rd was higher than the wild type wing disc.Bam is closely related to the differentiation of stem cells.As the stem cells begin to differentiate,Bam expression is gradually increased^[11].The Bam expression in the proliferative part of ectopic expression of Dichaete'wing disc may be decreased compared to the wild type wing disc.E-cad,its function is Cell-cell connection and the low expression makes decreased of the correlation between cells,and it is easy to metastasize^[12].After Ectopic expression of Dichaete,the expression of E-cad in the proliferative part is higher than wild type's.Therefore,it is speculated that ectopic expression of Dichaete can induce the production of stem cells to a certain extent and reverse the status of the primordial of this organ,which may be one of the reasons for the formation of new wing pouch in wing disc.Conclusion:In leg disc,ectopic expression of Dichaete increases apoptosis and leads to the development of adult leg malformation.These phenotypes maybe due to Dll upregulation in leg disc.In the wing disc,ectopic expression of Dichaete functions through the Wg/Vg signaling pathway.In different regions of the wing disc,the regulation of Wg is different.In the wing pouch,Wg expression is downregulated,which in turn inhibits Vg,causing apoptosis,increasing adult wing defects.In the proliferative part of notum,ectopic expression of Dichaete results in the formation of Wg loop,which in turn lead to the overproliferationin this area,the expression of Vg in the area of proliferation,the formation of a new wing pouch,and the formation of additional New wing.In addition,ectopic Dichaete expression may induce the appearance of some stem cell features in the proliferating cells.