Document Type

Thesis

Date of Award

10-2025

School/College

College of Science, Engineering, and Technology (COSET)

Degree Name

MS in Biology

Committee Chairperson

Dr. Shodimu-Emmanuel Olufemi

Committee Member 1

Dr. Desirée Jackson

Committee Member 2

Dr. Ayodotun Sodipe

Committee Member 3

Dr. Roderick Holmes

Abstract

One of the neurodegenerative diseases that affect the human brain is Alzheimer's disease (AD). It progressively destroys memory, thinking skills, and other critical mental functions of the brain. It is the most common cause of dementia due to the loss of cognitive functions. However, it differs from dementia, which includes other diseases resulting in cognitive deterioration and causing a person to lose independence and functionality. The apolipoprotein E (APOE) gene influences Alzheimer's risk. APOE protein transports cholesterol and other types of fat in the bloodstream. When the process fails, it contributes to the development of AD. Three genotypes of APOE alleles (ε2, ε3, ε4) located on chromosome 19q3 are genetic risk factors for dementia, Alzheimer's disease, and cardiovascular disease (CVD). In the outside and inside of the brain neurons, the buildup of amyloid protein plaques and neurofibrillary tangles (tau protein hyperphosphorylation) leads to cell death and brain shrinkage over time. Allele ε3 is common in half of the general population, while APOE ɛ4 is associated with a higher risk of AD. The possible combination of APOE alleles is ε2, ε2; ε2, ε3; ε2, ε4; ε3, ε3; ε3, ε4; ε4, ε4 (1, 2). DNA sequencing, Real-time PCR, and high-throughput protocol for single nucleotide polymorphism analysis are methods that detect APOE alleles. They are laborious and expensive. Because of these difficulties, this study develops a rationale to identify restriction sites in the APOE alleles; the restriction sites will distinguish between the APOE alleles and study the gene expression of genes and microRNAs (miRNAs) associated with AD. Gene expression establishes whether genes are on/off switches to control RNA molecules and proteins synthesized in cells, which can be associated with normalcy or a disease state. microRNAs are small, noncoding RNA molecules containing 21–23 nucleotides that regulate cell protein synthesis. Based on the rationale, the study aims to demonstrate that restriction enzyme digestion is easier and less laborious in analyzing APOE alleles in AD patients and demonstrate that the gene expression of the associated AD genes and miRNAs is suitable for determining differences in the APOE alleles in AD because the RNA expression of INSR, NANOG, GLRA1, hsa-let-7c, hsa-miR-195, and hsa-miR-7704, differs among the AD brain samples. Previous studies that used amplified end-PCR DNA products to identify APOE alleles, using different restriction enzymes (3, 4, 5, 6). This study is the first to use restriction enzyme HinP1I digestion of cDNA of Alzheimer disease (AD) samples to identify APOE alleles and to measure RNA expression of genes and miRNAs that play a significant role in the brain. Statistical analysis also validates the RNA expression of the genes and miRNAs.

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