The Role And Mechanism Of Small G Protein Ran In The Resistance Of Drosophila Kc Cells To Deltamethrin Stress

Deltamethrin(DM)is one of the most effective insecticides known at present and is widely used to control crop and health pests.However,widespread use not only leads to global resistance but also to environmental pollution and various toxic effects of mammalian and non-mammalian organs.Hence,it is very important to study the resistance mechanism of DM in depth.The small GTPase Ran plays an important role in several key cellular processes throughout the cell cycle,one of the most prominent of which is to regulate nucleoplasmic transport.We have previously found that DM stress could stimulate the high expression of Ran in Drosophila Kc cells,furthermore,DM-induced apoptosis was suppressed after overexpressing Ran,while interfering Ran had the opposite results.The above findings suggested that Ran system participates in DM stress.Keap1-Nrf2-ARE pathway plays a wide range of cellular protective functions in anti-tumor,anti-stress,anti-apoptosis,anti-inflammatory response and so on.When attacked by reactive oxygen species,nuclear transcription factor Nrf2 is dissociated from Keap1 and is translocated into the nucleus,which then interacts with antioxidant response element(ARE)to induce the expression of detoxification enzyme.We have also confirmed that Nrf2 protein in the nucleus was increased and accompanying the high expression of target detoxification enzyme genes(CYP450,CAT,GST,SOD et al.)when cells were stimulated by DM,which revealed that Keap1-Nrf2-ARE pathway was associated with DM stress.The focus of this study is to further explore the association and role between small G protein Ran and signaling pathways such as Keap1-Nrf2-ARE pathway in DM stress.The main results are as follows:1)Treatment with DM was found to result in a significant decrease in the portion of Ran in nucleus.Our results suggested that DM changes the distribution of Ran between nucleus and cytoplasm.2)Under DM stress,in Drosophila Kc cells that overexpressing Ran,nuclear transcription factor Nrf2 is present in a higher concentration in the nucleus,expression of detoxification genes(Cyp4d20,Cyp4ae1,Gst D5,Sod3,et al.)was significantly up-regulated and the DM-induced apoptosis was significantly lower than that of the control group.3)Interfering Ran using RNAi technique leads to the suppression of the nuclear import of Nrf2 which then down-regulates the expression of detoxification genes,ultimately resulting in a significant increase in apoptosis.Furthermore,after interfering Ntf2,a nuclear transport factor that interacts with Ran to perform a function in the nuclear transport,the results produced are similar to those produced by interfering Ran.4)The concentration of Dif in the nucleus was affected by DM stimulation,and that was increased obviously by overexpressing Ran;the expressions of Dif and Drsl1 were increased significantly by overexpressing Ran.As expected,Kc cells that interfering Ran or Ntf2 present opposite results compared with cells that overexpressing Ran.We can draw the conclusion that Ran may a key player involved in DM stress through Keap1-Nrf2-ARE pathway and Toll signaling pathway by regulating the nuclear location of Nrf2 and Dif.