Aluminum is an environmental
neurotoxin that comes extensively in contact with human beings. Animal and human studies demonstrated that
aluminum exposure increases the deposition of
beta amyloid proteins in the brain as it was observed in
Alzheimer's disease. The purpose of this study was to investigate whether miR-29a/b1 affected the expression of beta-secrete
enzymes (BACE1) in the process of
amyloid β-
protein (Aβ) deposition caused by
aluminum exposure. The study was performed using two different cell lines. Our results showed that after rat primary cortical neurons were exposed to
aluminum, BACE1 gene and
protein levels increased to different degrees, and the expression level of Aβ1-42 increased. In
aluminum-exposed groups, the expression of miR-29a and miR-29b1 decreased, while the expression of
amyloid protein Aβ1-42 and BACE1 increased. In miRs transfection groups, the expression of
amyloid protein Aβ1-42 and BACE1 decreased.
Aluminum may affect the expression of BACE1 by lowering miR-29a and miR-29b1. AEK293 cells were utilized in this research since they present elevated levels of miR-29a and miR-29b1. After HEK293 cells were exposed to
aluminum alone, BACE1
mRNA and BACE1
protein expression levels increased with the increase of
aluminum exposure dose (p < 0.05), and the level of Aβ1-42 also increased (p < 0.05). Compared with the group exposed to
aluminum alone at the same doses, the expression levels of BACE1
mRNA and BACE1
protein in the miRs transfected plus
aluminum-exposed groups significantly decreased (p < 0.05), and the level of Aβ1-42 also decreased (p < 0.05). This result is consistent with the investigation in rat primary neurons. The results of two types of cells showed that
aluminum may cause abnormal down-regulation of the expressions of miR-29a and miR-29b1, thus negatively regulating the increase of BACE1 expression and finally leading to the increase of Aβ.