Molecular Mechanism Of Endoplasmic Reticulum Stress Regulating YIPF2

With the rapid increase of cancer incidence,finding an effective treatment for cancer has become an urgent problem in scientific research and medicine.At present,lung cancer has become the most deadly type of cancer in the world.Therefore,it has become a matter of close concern for all people to quickly find an effective treatment for lung cancer.In recent years,TRAIL(TNF-related apoposis-inducing ligand)and its receptor mediated apoptosis mechanism of tumor cells have become a hotspot.TRAIL receptor belongs to the tumor necrosis factor receptor superfamily,and usually has 4 members:TNFRSF10A(DR4),TNFRSF 10B(DR5),TNFRSF 10C(Decoy receptor 1,DcR1)and TNFRSF10D(Decoy receptor 2,DcR2).TRAIL receptor-mediated apoptosis is achieved by the death domain in the intracellular segment of the receptor protein.After the binding of the death receptor on the cell membrane with TRAIL,trimerization occurred,and the intracellular segment of the receptor molecule formed a death-inducing signal complex with FADD and CASP8.CASP8 and CASP3 were activated sequentially to induce apoptosis.On the other hand,CASP8 can activate the mitochondrial pathway by cutting and activating tBid,and amplify the death signal to induce cell apoptosis.YIPF2 belongs to the YIP1 family.It is a transmembrane protein and be composed of 316 amino acids.It has three domains:N-terminal free in the cytoplasm,a five-fold transmembrane motif,and C-terminal free in the lumen.YIPF2 is mainly distributed in ER and Golgi apparatus.In addition,the IRE1?-XBP1 signaling pathway is a conserved signaling pathway in the unfolded protein response(UPR).XBP1 is an X-box binding protein with two shear bodies,XBP1U and XBP1S.In ER stress,IRE1a cuts 26 nucleotides in the coding region of XBP1U mRNA to produce transcription factor XBP1S,and XBP1S enters the nucleus to function as a transcription factor.Preliminary laboratory data showed that YIPF2 could regulate TNFRSF10B and induce apoptosis in NSCLC.Small molecule chemotherapy drugs can induce the occurrence of apoptosis by ER stress.It is interesting that we found in the promoter region of YIPF2 exists the potential binding sites of transcription factor XBP1S through access to the database.Based on the above findings,we conducted the following four aspects of research:(1)YIPF2 promotes the occurrence of apoptosis induced by endoplasmic reticulum stress.we oeverexpressed YIPF2 and treated with TG or TM in non-small cell kung cancer cells,the Western Blot result showed that the overexpression of YIPF2 enhanced the occurrence of ER stress-induced apoptosis.In addition,we found that the distribution of TNFRSF10B on cell membrane was increased by flow cytometry.Knocking down YIPF2 and treating the cells with TG or TM reduced the occurrence of apoptosis caused by ER stress,while inhibiting the distribution of TNFRSF10B in the cell membrane.(2)The increase of YIPF2 is dose-dependent and time-dependent with XBP1S.we treated cells with TG or TM,Western Blot revealed that the expression of YIPF2 and XBP1S were induced in a dose-dependent and time-dependent manner.(3)XBP1S promotes the expression of YIPF2 at the transcription level.We verified that XBP1S regulated the expression of YIPF2 at the transcriptional level through RT-PCR and Firefly Luciferase Gene Assey.(4)XBP1S regulates TNFRSF10B by promoting the expression of YIPF2,and then causes the occurrence of apoptosis.We overexpressed XBP1S in non-small cell lung cancer cells,treated with TG or TM,we found that the levels of YIPF2 and TNFRSF1B both increased,and promoting the ER stress-induced apoptosis.We knocked down XBP1S and treated with TG or TM,we found that the levels of YIPF2 and TNFRSF10B both decreased,and inhibiting tne ER stress-induced.apoptosis.Next,we verified through that XBP1S caused the increase of TNFRSF10B level by regulating YIPF2,and causing the occurrence of apoptosis through segregation experiment.This study provides a new mechanism for ER stress-induced apoptosis,which will provide a new idea and a better treatment scheme for the treatment of lung cancer.