Change in INSR, APBA2 and IDE Gene Expressions in Brains of Alzheimer's Disease Patients

Background: Alzheimer's disease (AD) is defined as a progressive and irreversible neurodegenerative disorder, the onset of which is mainly characterized by decreased cognition, memory loss, and mental confusion. Objective: This study sought to quantify mRNA expression of the APBA2, INSR and IDE genes in brain samples from patients with AD and controls. Methods: We investigated the mRNA expression of the APBA2, INSR and IDE genes in 150 RNA samples from entorhinal cortex, auditory cortex, and the hippocampus of individuals with AD and elderly controls using real time PCR. APOE genotypes were determined by PCR-RFLP. Results: When the total brain samples were analyzed collectively, a decrease in IDE gene expression was found in AD patients relative to healthy elderly controls. However, when the samples were analyzed separately according to the region of the brain, there was a significant upregulation of INSR expression in the hippocampus and the entorhinal cortex in the AD patient group. We did not observe any statistical differences when gene expression was compared in the different regions of the brain of AD patients. When the E4 allele of apolipoprotein-E was considered in AD patients, the presence of this allele was found to be associated with decreased APBA2 gene expression. The same analysis using the INSR and IDE genes showed no significant statistical differences. Conclusion: These results support the hypothesis that APBA2, IDE, and particularly INSR gene expression in different areas of Alzheimer’s patient’s brains could represent new markers for use in clinical diagnoses in the near future.