Estrogen Activates AP-1 Transcriptional Activity Through ER-α36 Mediated Rapid Estrogen Signaling Pathway

Objective: For a long time,people think estrogen acts through its receptor,ER-α66,activates AP-1 transcriptional activity through direct interaction with the AP-1 proteins.In this thesis,we explored another novel pathway by which estrogen activates the transcriptional activity of AP-1: estrogen through ER-α36mediated rapid estrogen signaling directly phosphorylates AP-1 proteins and activates the transcriptional activity of AP-1.We also further investigated the signaling pathway involved.Methods:(1)In cervical cancer Hela cells and human embryonic kidney 293 T cells,the dual-luciferase reporter gene assay was used to detect the activation of AP-1 and ERE driven report gene transcription mediated by ER-α36 and ER-α(ER-α66)respectively.(2)ER-α36-mediated rapid estrogen signaling was verified using Western blotting analysis.(3)The EGFR inhibitor AG1478 and the Western blot analysis were used to probe the activation of AP-1 and the possible pathways involved.(4)The nuclear entry of ER-α36 and ER-α66 was studied using the nuclear and cytoplasmic protein separation assay.Results:(1)In the two cell lines,ER-α36 activated the transcriptional activity of AP-1 mediated report gene,but failed to activate the transcriptional activity of ERE mediated report gene.(2)In the two cell lines,the EGFR inhibitor AG1478 inhibited activation of the AP-1 induced by estrogen as well as the rapid estrogen signaling.(3)ER-α66 activated the transcriptional activity of ERE driven reporter,but failed to activate the transcriptional activity of AP-1 driven reporter.(4)In the two cell lines,ER-α36retained ER-α66 in the cytoplasm and reduced its nuclear entry under estrogen treatment.Conclusions: ER-α36 mediated rapid estrogen pathways such as the MAPK/ERK and AKT directly activates AP-1 transcriptional activity.