ABSTRACT
Objective To introduce a practical method that can be used to efficiently express,purify and identify Alzheimer's disease (AD) related beta-site app-cleaving enzyme 1 (BACE1) in common eukaryotic cells.Methods BACE1 cDNA was fished out from human brain cDNA library and ligated into the pEGFP-c3 expression vector,and then,the recombinant plasmid was transfected into the HEK293 cells.The BACE1 protein was purified with TALON Mental Affinity Resins column.The target protein was identified by Western blotting and fluorescence resonance energy transfer (FRET).BACE1 Activity Assay Kit was employed to test the activity of purified BACE1 in vitro.The recombinant BACE1/pEGFP-c3 plasmid and amyloid precusor protein (APP)/pDsRed-Monomer-N1 plasmid were co-transfected to the HEK293 cells and the cleavage activity of BACE1 in the cells was identified by Western blotting.Results The sequencing data of the obtained BACE1 gene were identical with those in GenBank.Activity test showed that the fluorescent values of blank controls,expressed BACE1 and standard BACE1 were 55.013±3.597,1836.629±154.195 (n=3) and 2639.548±207.1901 (n=3),respectively;as compared with the control group,significant differences were noted in both of the two groups (F=78.681,P=0.000);however,there is no significant difference between expressed BACE1 and standard BACE1 groups (P＞0.05).Westem blotting showed the co-transfected BACE1 could cleave APP in HEK293 cells and the CTF-APP band was detectable.Conclusion A practical protocol is established for high expression,purification and identification of BACE1 in HEK293 cells,which is helpful to obtain BACE1,an important molecular target in AD research and treatment.
ABSTRACT
Objective To explore whether prenatal stress promotes formation of chronic stress-induced hippocampal amyloid β (Aβ) protein in 6-month-old male offspring mice and its mechanism.Methods The APPswe/PSIdE9 double transgenic mice were divided into 4 groups according to the prenatal stress and offspring mice stress:prenatal control-offspring control group (CC group),prenatal control-chronic offspring stress group (CT group),chronic prenatal stress-offspring control group (TC group),and chronic prenatal stress-chronic offspring stress group (TT group) (n=18).The number of amyloid plaques in brains was checked using Congo red staining.ELISA was used to examine the hippocampus levels ofamyloid-β proteins (Aβ1-42 and Aβ1-40) in the offspring mice;β-site APP-cleaving enzyme 1 (BACE1) activity was detected using fluorospectrophotometry.Additionally,Western blotting were used to observe the expression levels of phosphorylated eukaryotic initiation factor 2α (p-eIF2α),phosphorylated protein kinase R [PKR]-like ER kinase (p-PERK),glucose-regulated protein 78 (Grp78) and β-site BACE1 in the hippocampus.Results As compared with that in the CC group,the number of amyloid plaques in brain in CT,TT and TC groups was increased.The expressions of p-eIF2α,p-PERK,Grp78,BACE1,Aβ1-40 and Aβ1-42 in the hippocampus of CT group were significantly increased as compared with those in the CC group (P＜0.05).The expressions of p-eIF2α,p-PERK,Grp78,BACE1,Aβ1-40 and Aβ1-42 in the hippocampus of TT group were further significantly increased as compared with those in the CT group (P＜0.05).There was no significant difference in BACE1 activity among the different groups (P＞0.05).Conclusion The prenatal stress can promote the formation of hippocampal Aβ protein induced by chronic stress in 6-month-old male offspring mice,whose mechanism may be that prenatal stress aggravates hippocampal neurons endoplasmic reticulum stress,activates the PERK,then causes eIF2 alpha phosphorylation,and finally promotes BACE1 expression.