Roles Of Vesicular Transport Related Proteins VAMP7,EMC3 And Sh3PX1 In Drosophila Development

Drosophila is an important model organism for the study of developmental biology.We screen the protein involved in the vesicles transport through the RNA interference experiments and find that VAMP7 and EMC3 have regulatory effect on the transport and signal transduction of the morphogenic factor Wingless.We also find that SH3PX1 play a role during the early stage of Drosophila spermatogenesis.VAMP7 is a SNARE protein that regulates vesicle fusion mainly in the endocytosis pathway.During the development of Drosophila wing discs,VAMP7 regulates the intracellular trafficking of Wingless(Wg),a homolog of Wnt in Drosophila.When VAMP7 is reduced or deleted,Wg increases and accumulates in the Rab4 dependent rapid recycling endosomes while the amount of Wg in the other vesicles do not change significantly.These indicates that the increase of Wg is not randomly.We also observe a shift in the distribution of Dally-like(Dip),a membrane protein that interacts with Wg and regulates its transport.Dip increases in the top region of Drosophila wing epithelial cells and accumulates in the same Rab4 dependent rapid recycling endosomes with Wg.In addition to favoring Wg transport,Dip also inhibits the expression of Wg downstream target senseless(sens),as a negative feedback regulator.The dual function of Dip may limit sens expressing in the cells adjacent to Wg-expressing row.Previous studies have found that both the amount and transport route changes of Dlp affect the expression of sens.In our study,Sens weakens when VAMP7 is deficient.In addition,we also examine other morphogenetic factors and membrane protein that is involved in Wg trafficking.However,we find no significant change except phosphatidylinositol-anchor protein,suggesting that VAMP7 has some specificity.Taken together,we hypothesize that VAMP7 may be involved in the regulation of Wg and Dip transport.As the loss of VAMP7 results in the accumulation of Wg and Dip in Rab4-dependent circulating endosomes,the changes in this transport pathway may affect Wg concentration gradient formation and Wg signaling.In addition,we find that Wg accumulates in the endoplasmic reticulum of secretory cells when Reticulum Membrane Complex3(EMC3)is mutant.Unlike VAMP7 mutation,a variety of types of protein transport are affected,indicating that the role of EMC3 in the transport pathway is not as special as VAMP7.In RNA screening experiments,we also observe male sterility of Drosophila with SH3PX1 deletion.And the further study reveals that the individualization of sperm could not be completed.In the early stages of individualization,some organelles can not move synchronously.We speculate that SH3PX1 may be involved in the process of organelles movement.Previous studies mostly focused on the regulation of the developmental process at the gene expression level.In recent years,the regulation of protein transport in development has drawn more and more attention.Here,we find that three proteins involved in vesicular trafficking play roles in the regulation of developmental processes.Our study suggests a possible model for how signaling molecules regulate cell differentiation by altering the spatial location.