The effect of early growth response 1 on levels of Amyloid-ß 40 peptide in U87MG cells.

A recent study has shown that early growth response 1 (EGR1) plays a critical role in the ß-amyloid cascade and tau hypotheses. In addition, evidence has suggested that EGR1 can regulate levels of amyloid-beta peptides, key molecules in the pathogenesis of Alzheimer's disease (AD). However, whether EGR1 is a deleterious or protective factor in the AD is still controversial. In this present study, we constructed an overexpression plasmid, CMV-EGFP-EGR1-Kanamycin, and transfected it into U87MG cells to investigate the effects of EGR1 expression on amyloid-ß (1-40) peptide (Aß40) levels. U87MG cells transfected by CMV-EGFP-EGR1-Kanamycin and CMV-EGFP-Kanamycin were assigned, respectively, to experimental and control groups. Fluorescence microscopy was used to observe transfection efficiencies of the plasmids after 6 hours. EGR1 messenger RNA levels were measured by quantitative reverse transcription polymerase chain reaction. Aß40 secretion was analyzed by enzyme-linked immunosorbent assay. Expression of the amyloid precursor protein, beta-secretase enzyme, and presenilin 1 proteins were analyzed by Western blot analysis. The results showed that EGR1 overexpression increased Aß40 secretion in vitro, possibly through increasing BACE1 expression. Based on these results, EGR1 might be a promising therapeutic target for the AD.