NR AOWH
AU Manson,J.C.; Barron,R.M.; Tuzi,N.L.; Baybutt,H.N.; Aitchison,L.; Moore,R.; Melton,D.; Ironside,J.; Will,R.
TI How does host PrP control TSE disease?
QU International Conference - Prion diseases: from basic research to intervention concepts - TSE-Forum, 08.10.-10.10.2003, Gasteig, München - Oral sessions OS-16
PT Konferenz-Vortrag
AB
PrP is central to the TSE disease process and has been hypothesised to be the infectious agent. Polymorphisms in the PrP gene of a number of species are associated with different incubation times of disease following exposure to an infectious agent and mutations in the human PrP gene can apparently lead to spontaneous genetic disease. Strains of TSE agent are proposed to be generated and maintained through differences in glycosylation or conformation of PrP and the barrier to infection between species is thought to be due to the differences in the sequence of PrP between different species.
In order to test these hypotheses and define the role of PrP in the TSEs, we have introduced specific modifications into the endogenous mouse Prnp gene by gene targeting. The PrP gene alterations have been introduced into embryonic stem cells in culture, following which the mutated cells were reintroduced into a blastocyst where they contributed to a developing embryo. The mutated PrP gene is in the correct location under the control of the endogenous regulatory sequences of the murine PrP gene. Thus the mutated PrP gene is expressed in the same tissues and amounts as the wild type Prnp gene. This strategy therefore allows the effect of specific mutations in the PrP gene to be assessed.
We have addressed the role of the 108 and 189 polymorphisms in murine PrP in the control of incubation time of disease and have established that both polymorphisms control incubation time of TSE in mice and are investigating the mechanism by which this is achieved. We have introduced mutations into the Prnp gene which prevent glycosylation at each or both of the two N-linked glycosylation sites of PrP and are using TSE infection of these mice to establish if PrP glycosylation has a role in strain targeting or strain determination. We have found no evidence for a spontaneous neurological disease associated with the 101L mutation or for instability resulting from the 101L mutation as has been suggested for the 102L mutation in humans. However inoculation with a number of different TSE strains has demonstrated that the 101L mutation alters susceptibility of the mice to TSE infectivity from three different species suggesting an important role for the N-terminus of PrP in the transmission of TSE between species. We are further investigating the role of the sequence of the host PrP gene in determining susceptibility by replacing the murine PrP gene with that of human or bovine PrP.
We have thus established that the gene targeting approach can produce models for TSE disease which address fundamental questions associated with these diseases. We aim to use these models to address central issues including the origin of strains, the species barrier and the nature of the infectious agent.
This work is supported by BBSRC, MRC, DEFRA and DoH
AD JC Manson, R Barron, N Tuzi, H Baybutt, L Aitchison, Institute for Animal Health, Neuropathogenesis Unit, Edinburgh; R Moore, D Melton, University of Edinburgh, Edinburgh; J Ironside, R Will, CJD Surveillance Group, Edinburgh
SP englisch
PO Deutschland