CDK5 and MAPT Gene Expression in Alzheimer's Disease Brain Samples

Background: Alzheimer's disease (AD) is a neurodegenerative disorder characterized by extracellular amyloid plaque and neurofibrillary tangles in the brain. Studies have shown that neurons are able to re-enter the cell cycle, but not enough to enable full replication. This leads to cell death and consequent neurodegeneration. Objective: This study aimed to characterize the expression of the MAPT gene and CDK5 (the gene involved in cell cycle regulation) in brain samples from patients with AD and controls. Method: The real-time-PCR technique was used to characterize 150 samples from three areas of the brain (entorhinal cortex, auditory cortex, and hippocampus) of 26 AD patients and 24 healthy elderly subjects. Results: When the brain samples were analyzed collectively, a decrease in CDK5 and MAPT gene expression was found in AD patients. When each groups' samples were separated by area of the brain and compared, significant differences were found in CDK5 expression in the hippocampus and the entorhinal cortex. In both cases, mRNA was lower in the AD group (p=0.0001); however, the same analysis using the MAPT gene revealed no significant statistical differences. No statistical differences were found when gene expression was compared between the different regions of the brain within each group. Conclusion: These results may contribute to a better understanding of the involvement of CDK5 and MAPT genes in AD in that they consider different areas of the brain that are affected differently based on disease progression. The main challenge is to establish an effective therapy for this debilitating disease in the future.