Date of Award

August 2017

Degree Type

Thesis

Degree Name

Master of Science

Department

Biomedical Sciences

First Advisor

Wail Hassan

Committee Members

Joseph Goveas, Anthony Azenabor

Abstract

Alzheimer’s disease is an irreversible and progressive brain disorder that affects memory and thinking skills. It is considered to be one of the most important causes of dementia in older adults. The disease is accompanied by accumulation of amyloid beta (Aβ) plaques in the brains of patients and presence of neurofibrillary tangles (NFTs) in the nerve tissue. The tangles are formed by a protein known as protein-tau (p-tau). Aβ plaques are responsible for neurodegeneration, cognitive decline, and loss of memory in patients affected with Alzheimer’s disease. It is estimated that Alzheimer’s disease ranks third, just behind heart disease and cancer, as a cause of death for the elderly in the United States. AIRAP and AIRAPL are ubiquitin-binding proteins that are thought to enhance the function of the proteasome by clearing out the misfolded proteins from the brain. Previous studies have shown that AIP-1 (a homologue of AIRAP and AIRAPL) was overexpressed in a Caenorhabditis elegans disease model which in turn helped to reduce the accumulation of Aβ and thus had a protective effect against Aβ toxicity. The purpose of our study is to test whether AIRAP and AIRAPL are protective against the toxicity associated with Aβ in mammalian neuronal cells. We are hypothesizing that AIRAP and AIRAPL are protective against Aβ toxicity in HT22 hippocampal cells, which would significantly decelerate the progression of Alzheimer’s disease. We have manipulated the expression of AIRAP and AIRAPL and studied the effect of overexpression and knockdown on Aβ toxicity. Overexpression was achieved by establishing transfected cell lines overexpressing AIRAP and AIRAPL with help of a CMV constitutive promoter. On the other hand, knockdown of genes was attained using specific DsiRNA. Using Trypan Blue staining, we found that cell lines overexpressing AIRAP/AIRAPL could lower Aβ toxicity, thus increasing the number of viable cells. Additionally, knocking down AIRAP/AIRAPL expression appeared to worsen the condition of cells, as the number of dead cells increased, in response to Aβ treatment. With help of real-time PCR, mRNA levels of AIRAP and AIRAPL was measured. It was shown that expression of both AIRAP and AIRAPL was enhanced during the initial stages of induction in cell line having induced Aβ. However, as the induction time increased, the expression levels started to fall off. Further studies are essential to know the exact mechanism behind AIRAP/AIRAPL protection against Aβ toxicity.

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