Browsing by Person "Melton, David W."

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The 101L mutation in murine PrP can alter transmission across three species barriers
(2002) Barron, Rona; Jamieson, Elizabeth; Thomson, Val; Melton, David W.; Will, Robert; Ironside, James; Manson, Jean C.
Changing a single amino acid in the N-terminus of murine PrP alters incubation time across three species barriers
(EMBO Press, 2001-09-17) Barron, Rona; Thomson, Val; Jamieson, Elizabeth; Melton, David W.; Ironside, James; Will, Robert; Manson, Jean C.
The PrP gene of the host exerts a major influence over the outcome of transmissible spongiform encephalopathy (TSE) disease, but the mechanism by which this is achieved is not understood. We have introduced a specific mutation into the endogenous murine PrP gene using gene targeting to produce transgenic mice with a single amino acid alteration (proline to leucine) at amino acid position 101 in their PrP protein (P101L). The effect of this alteration on incubation time, targeting and PrPSc formation has been studied in TSE-infected animals. Transgenic mice carrying the P101L mutation in PrP have remarkable differences in incubation time and targeting of central nervous system pathology compared with wild-type littermates, following inoculation with infectivity from human, hamster, sheep and murine sources. This single mutation can alter incubation time across three species barriers in a strain-dependent manner. These findings suggest a critical role for the structurally ‘flexible’ region of PrP in agent replication and targeting of TSE pathology.
Polymorphisms at codons 108 and 189 in murine PrP play distinct roles in the control of scrapie incubation time
(Microbiology Society, 2005-03-01) Barron, Rona; Baybutt, Herbert; Tuzi, Nadia L.; McCormack, James; King, Declan; Moore, Richard C.; Melton, David W.; Manson, Jean C.
Susceptibility to transmissible spongiform encephalopathies (TSEs) is associated strongly with PrP polymorphisms in humans, sheep and rodents. In mice, scrapie incubation time is controlled by polymorphisms at PrP codons 108 (leucine or phenylalanine) and 189 (threonine or valine), but the precise role of each polymorphism in the control of disease is unknown. The L108F and T189V polymorphisms are present in distinct structural regions of PrP and thus provide an excellent model with which to investigate the role of PrP structure and gene variation in TSEs. Two unique lines of transgenic mice, in which 108F and 189V have been targeted separately into the endogenous murine Prnp a gene, have been produced. TSE inoculation of inbred lines of mice expressing all allelic combinations at codons 108 and 189 has revealed a complex relationship between PrP allele and incubation time. It has been established that both codons 108 and 189 control TSE incubation time, and that each polymorphism plays a distinct role in the disease process. Comparison of ME7 incubation times in mouse lines that are heterozygous at both codons has also identified a previously unrecognized intramolecular interaction between PrP codons 108 and 189.
A single amino acid alteration (101L) introduced into murine PrP dramatically alters incubation time of transmissible spongiform encephalopathy
(EMBO Press, 1999-12-01) Manson, Jean C.; Jamieson, Elizabeth; Baybutt, Herbert; Tuzi, Nadia L.; Barron, Rona; McConnell, Irene; Somerville, Robert; Ironside, James; Will, Robert; Sy, Man-Sun; Melton, David W.; Hope, James; Bostock, Christopher
A mutation equivalent to P102L in the human PrP gene, associated with Gerstmann–Straussler syndrome (GSS), has been introduced into the murine PrP gene by gene targeting. Mice homozygous for this mutation (101LL) showed no spontaneous transmissible spongiform encephalopathy (TSE) disease, but had incubation times dramatically different from wild-type mice following inoculation with different TSE sources. Inoculation with GSS produced disease in 101LL mice in 288 days. Disease was transmitted from these mice to both wild-type (226 days) and 101LL mice (148 days). In contrast, 101LL mice infected with ME7 had prolonged incubation times (338 days) compared with wild-type mice (161 days). The 101L mutation does not, therefore, produce any spontaneous genetic disease in mice but significantly alters the incubation time of TSE infection. Additionally, a rapid TSE transmission was demonstrated despite extremely low levels of disease-associated PrP.
A single amino acid alteration in murine PrP dramatically alters the TSE incubation time
(Springer, 2000) Manson, Jean; Barron, Rona; Jamieson, Elizabeth; Baybutt, Herbert; Tuzi, Nadia L.; McConnell, I.; Melton, David W.; Hope, J.; Bostock, C.
In order to investigate mutations linked to human TSEs, we have used the technique of gene targeting to introduce specific mutations into the endogenous murine PrP gene which resulted in a P101L substitution (Prnp a101L) in the murine PrP gene. This mutation is equivalent to the 102L mutation in the human PrP gene which is associated with Gerstmann-Sträussler syndrome. Since the mutated gene is in the correct chromosomal location and control of the mutant gene expression is identical to that of the wild type murine PrP gene, the precise effect of the 101L mutation in the uninfected and TSE infected mouse can be investigated in this transgenic model. Mice homozygous for this mutation (101LL) while showing no spontaneous TSE disease were more susceptible to TSE disease than wild type mice following inoculation with GSS infectivity. Disease was transmitted from these mice to mice both with and without the Prnp a101L allele. The 101L mutation does not therefore produce spontaneous genetic disease in mice but does dramatically alter incubation periods following TSE infection. Additionally, a rapid TSE transmission was demonstrated associated with extremely low amounts of PrPSc.
Transmission of murine scrapie to P101L transgenic mice
(Microbiology Society, 2003-11-01) Barron, Rona; Thomson, Val; King, Declan; Melton, David W.; Manson, Jean C.
The PrP protein is central to the transmissible spongiform encephalopathies (TSEs), and the amino acid sequence of this protein in the host can influence both incubation time of disease and targeting of disease pathology. The N terminus of murine PrP has been proposed to be important in the replication of TSE agents, as mutations or deletions in that region can alter the efficiency of agent replication. To address this hypothesis and to investigate the mechanisms by which host PrP sequence controls the outcome of disease, we have assessed the influence of a single amino acid alteration in the N-terminal region of murine PrP (P101L) on the transmission of TSE agents between mice. Mice homozygous for the mutation (101LL) were inoculated with TSE strains 139A and 79A derived from mice carrying a Prnpa allele, and 79V and 301V derived from mice carrying a Prnpb allele. Incubation times in 101LL mice were extended with all four strains of agent when compared with those in the corresponding mouse genotype from which the infectivity was derived. However, the degree to which the incubation period was increased showed considerable variation between each strain of agent. Moreover, the presence of this single amino acid alteration resulted in a 70 day reduction in incubation time of the 301V strain in Prnpa mice. The effect of the 101L mutation on murine scrapie incubation time appears therefore to be strain specific.