Generation of Stable Cell Lines Expressing Notch and Presenilin: Insights into the Function of Presenilin in Notch Signaling and Alzheimer's Disease
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Familial early-onset Alzheimer's disease (FAD) affects approximately 10% of all cases of Alzheimer's disease. F AD is associated with dementia and neurofibrillary tangles, but its most distinctive feature is the deposition of extracellular amyloid plaques. FAD is characterized by the autosomal dominant inheritance of mutant genes encoding the amyloid precursor protein (APP), presenilin 1 (PS1), and presenilin2 (PS2), which, in mutated forms, increase the formation of amyloid-𝛽 (A𝛽) plaques. These plaques are produced from the result of aberrantly processed APP molecules. Presenilins primarily reside in the endoplasmic reticulum and are thought to regulate protein trafficking. But, how mutated presenilins increase A𝛽 deposition is unknown. Known substrates of presenilin are the LIN12/Notch transmembrane receptors, which control cell fate decisions in diverse organisms. Like APP, Notch is a transmembrane protein that also undergoes proteolytic processing. Therefore, investigation into the regulation of Notch processing by presenilin can potentially offer more insight into presenilin' s role in Alzheimer's disease and how it affects normal molecular APP processing and aberrant APP processing leading to amyloid plaque formation. In this study, our initial goal was to generate stable cell lines expressing Notch and presenilin that would provide viable cell culture models for Notch and presenilin interactions. These interactions would then be examined by studying the formation of Notch cleavage products. We were able to generable these novel stable cell lines. Additionally, our analysis of Notch processing indicates that it occurs both in the presence and absence of presenilin and generates two fragments, the functional heterodimer and an intracellular domain thought to translocate to the nucleus to modulate gene expression. Overall, our data support a need for further investigation into our stable cell lines and the regulation of Notch by presenilin.With honors.