Study On The Mechanism Of XBP1Transcription Regulation By ATF6

Objective Determine the XBP1promoter transcriptional core sequenceand the effect on transcriptional activity of XBP1by ATF6in ERS ornon-ERS. Methods ATF6and ATF6two deletion mutants(S1P and S2P)eukaryotic expression vectors, pcDNA3.1(-)myc-ATF6/pcDNA3.1(-)myc-S1P/pcDNA3.1(-)myc-S2P.And XBP1reporter genevector pGL3-XBP1was also constructed. Besides, a series vectors of XBP1promoter truncated were designed and constructed on basis of XBP1promoter component elements. Firstly, XBP1promoter transcriptional coresequence was determined by the dual-luciferase reporter assay. Then theeffect on transcriptional activity of XBP1by ATF6and its two deletionmutants in ERS or non-ERS were analysed by western blotting. Design aseries of mutants according to XBP1promoter transcriptional activity,detection transcriptional activity of mutant. In the ERS or non-ERS,detection transcriptional activity of mutant by ATF6.Results The regionfrom-407bp to+133bp of XBP1promoter was the core sequence, however,the region from-2000bp to-407bp has no transcription activity. Mutationsbinding sites IRE CS,SP(-1879), XBP1transcriptional activity increased significantly. In ERS or non-ERS, Mutate IRE CS, SP(-1879), SP(-690)binding sites, up-regulation transcription activity of XBP1promoter byATF6. Conclusion The region from-2000bp to-407bp might be includedsome elements inhibiting transcription activity. During non-ERS state, thetranscription activity of XBP1promoter by ATF6and its two deletionmutants(S2P/S1P) were higher than control, And XBP1expression werealso increased after transfected with ATF6and its two deletionmutants;While in ERS state, the transcription activity of XBP1promoter byATF6and its two deletion mutants were reduced, And XBP1expressionwere also decreased after transfected with ATF6and its two deletion mutants.Collectively, XBP1transcription regulated by ATF6was of difference inERS or non-ERS. The transcription and expression of XBP1was upregulatedby ATF6during non-ERS, but was downregulated by ATF6during ERS.Binding sites IRE CS inhibition transcription activity of XBP1promoter byATF6.