| الوصف: |
The amyloid cascade hypothesis suggests that overproduction and accumulation of the neurotoxic amyloid beta (Aβ) peptide plays a central role in Alzheimer's disease (AD). Aβ is generated from the sequential cleavage of the amyloid precursor protein (APP) through the β-secretase pathway. Several isoforms of APP exist: APP695, APP751, and APP770, generated through alternative splicing of exons 7 and 8. Alternative splicing to produce APP695 involves exclusion of exon 7, encoding the Kunitz protease inhibitor (KPI), and exon 8. Studies show up-regulation of KPI-containing APP isoforms (APP770 and APP751) in AD and increase Aβ deposition, whereas APP695 is down-regulated. Furthermore, the AICD (Amyloid Intracellular Domain) which is preferentially produced from APP695 can translocate to the nucleus and act as a transcription factor for genes such as Neprilysin which acts to degrade Aβ. Therefore, APP695 is theorised to be protective against AD, with its loss coinciding with disease progression. This study sought to design Phosphorodiamidate morpholino oligomers (PMOs) specific to exons 7 and 8 of APP, targeting exonic splicing enhancer (ESE) sites, sterically hindering their binding, and modulating alternative splicing, thus increasing APP695 levels. In addition, this study assessed the efficacy of these PMOs and examined the protective effects of APP695 and its cleavage products by analysing downstream effects of splicing modulation. Results demonstrate that PMOs successfully induced alternative splicing events, modulating APP at the RNA and protein level, and significantly increasing APP695. Western blotting data confirmed the presence of the AICD peptide in protein samples from PMO transfected cells. Following this, qPCR data confirmed that PMO transfected cells show increased expression of key Aβ clearing proteins such as Neprilysin. The data collected in this thesis reinforces the theory that APP695 is protective against AD through the effects of the AICD. This strategy emerges as a potential therapeutic for AD treatment. |
