The use of transgenic models in recent years has shown that there is a relationship between PrP expression level and disease progression. Lower-than-normal expression leads to extended incubation period and clinical phase (Beuler, 1993; Manson et al., 1994). In contrast, overexpression shortens incubation period or generates novel neurological syndromes associated with degeneration of skeletal muscle, peripheral nerves and the CNS (Westaway et al., 1994). Natural differences in expression of PrP<SUP>C</SUP> resulting from a variety of mutations within the promoter, enhancer, intron or non-coding sequences could therefore play a part in determining whether a host is either susceptible or resistant to disease. This project was designed to investigate the potential of the sheep PrP gene 3'-untranslated region (UTR) to control expression of a reporter gene in neuroblastoma (N2a) cells of mouse origin. Interest in this region of the PrP gene results from sheep PrP genetic studies (Hunter et al., 1991), PrP mRNA (Hunter et al., 1994) and protein studies (Horiuchi et al., 1995). Sequence analysis of the PrP gene 3' UTR region showed that it was polymorphic and contained instability motifs and potential alternative polyadenylation signals. The deletion of 2.7 kb from the PrP gene 3' UTR was shown to result in altered expression of chloramphenicol acetyl transferase (CAT) at the post-transcriptional level in N2a lines but not in cell free systems. Further constructs were made by unidirectional deletions in the 3' UTR and results suggested that differences in the length of the 3' UTR can affect expression at the transcription and/or post transcriptional level. Additional experiments showed by deletion and site directed mutagenesis that an alternative polyadenylation signal ATTAAA at position 1525 can be used in 3' end processing of RNA in N2a cells. These findings may have implications both for the expression of the PrP gene in the natural host of scrapie and for development and progression of disease.
| Identifer | oai:union.ndltd.org:bl.uk/oai:ethos.bl.uk:642797 |
| Date | January 1997 |
| Creators | Cheung, Foo |
| Publisher | University of Edinburgh |
| Source Sets | Ethos UK |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
| Source | http://hdl.handle.net/1842/13370 |
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