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MRC Prion Unit
From fundamental research to prevention and cure
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Transgenic modelling of human prion disease, intermammalian transmission barriers and assessment of candidate therapeutics

The Unit is working to find alternatives to the use of laboratory animals in our research, but at this time some crucial work can only be done in mice. The transgenic team led by Dr Emmanuel A Asante have developed a key series of animal models of human prion disease. Our past studies using genetically modified mice that produce human prion protein with both the M and the V form have formed an important part of the scientific evidence confirming that variant Creutzfeldt Jakob Disease (vCJD) is the human counterpart of bovine spongiform encephalopathy (BSE), commonly known as “mad cow disease”.

Dr Asante and his team are also modelling inherited forms of prion disease that are associated with specific mutations (genetic changes) in the prion protein gene. Various genetic mutations are seen in patients with inherited forms of prion disease (also known as familial CJD and Gerstmann Straussler Scheinker syndrome (GSS)), and there are more than 30 of these disease-associated mutations known. The Transgenic team’s work on inherited prion diseases so far shows that the different mutations have their own unique characteristics and should therefore be investigated each in their own right. For example, a comparative study published in 2009 of two such mutations, E200K (an example of familial CJD) and P102L (an example of GSS), showed clearly that the mutations behaved differently.  Transgenic mice carrying the E200K mutation were readily infected to the same extent, whether challenged with sporadic CJD (of unknown cause, but not associated with any known mutation) or with human prions from patients with the same familial E200K mutation. In contrast, transgenic mice carrying the GSS P102L mutation (designated 102LL Tg27) were readily infected by prions from GSS patient brain, but interestingly, incubation period (the time from inoculation to the appearance of disease), was relatively much longer for sporadic CJD prions. Follow-up studies showed that when the 102LL Tg27 transgenic mice were challenged with prions from GSS patient brain, they produced exclusively, a form of human prion that could only infect more mice carrying the same P102L mutation (Figure 1). In sharp contrast to modelling P101L (equivalent amino acid position on mouse PrP) where both mutant and wild type mice were equally susceptible, wild type mice and transgenic mice expressing wild type human prion protein were completely resistant to the homogeneous (purified) form of GSS prions produced in the 102LL Tg27 mice (Figure 1).

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Figure 1. Histology depicting modelling of inherited prion disease GSS-P102L. Prions from GSS patient brain when passaged once in 102LL Tg27 transgenic can only infect mice of the same genetic make-up, and transgenic mice expressing non-mutant human PrP either of the methionine-129 (panel B, E) or valine-129 (Panels C, F) form are completely resistant. Panel D is negative when probed with antibody ICSM 35 because only mutant prions were made in the brains of the 102LL Tg27 transgenic mice. Asante et al., 2015 PLoS Pathog. 2;11(7):e1004953. doi: 10.1371/journal.ppat.1004953 .

As well as investigating if all inherited forms of prion disease meet the criteria for being classified as prion diseases, the team’s modelling work is also aimed at confirming the prediction of the “protein only” hypothesis that inherited prion diseases can occur spontaneously (without any external factors other than having the faulty gene).

During our field studies into kuru, a form of human prion disease restricted to the Fore linguistic group of Papua New Guinea, we identified a novel genetic change (G to V at amino acid position 127) resulting in two alternate forms of the human prion gene (referred to as a polymorphism) that appeared to confer strong protection against kuru infection. Kuru was caused and indeed spread by endocannibalism, the consumption of dead kin as a mark of respect. This G127V polymorphism was unique to the affected population and appeared to have been selected for naturally in response to the kuru epidemic. Clinical, genetic and epidemiological data strongly suggested that carriers of both forms of the gene (127GV heterozygotes) must have been completely resistant to kuru infection, but this assertion needed to be investigated experimentally.

Dr Asante and his team have developed mouse models of this new genetic variant and demonstrated in a paper published in Nature in June 2015, that not only is 127GV heterozygosity protective against kuru and classical CJD prions, but the protective mechanism (referred to as dominant negative inhibition) is completely different from the mechanism of the worldwide M129V polymorphism (inhibition of protein-protein interaction) (Figure 2).

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Figure 2: Modelling of kuru in mice. Transgenic mice either homozygous (VV) or heterozygous (GV) at amino acid position 127 of the human prion protein are completely resistant to (a) kuru and (b) classical CJD prions. (Asante et al., 2015; Nature 522: 478-481).

A major difference between the new G127V polymorphism and the well-characterised M129V polymorphism (where both MM and VV homozygotes are susceptible to human prions) is that mice homozygous for the variant 127V are completely resistant to all forms of human prions. A remarkable conclusion from these kuru modelling studies is that, if the mortuary ritual and consequently the kuru epidemic had continued, the epicentre of the kuru-affected region may have repopulated with kuru-resistant individuals.

Dr Asante and his team are also working on differentiating human prion strains whose existence is one of the most enigmatic concepts within prion biology. The team are also poised to investigate any animal prion disease with potential zoonotic (animal disease that can pass to humans) potential that may come to light in future. The team is currently using genome editing technology to generate models for studying a new mutation that has a unique and unusual clinical presentation for a prion disease.

The Transgenic team have produced highly characterised models that are being used to evaluate candidate therapeutic drugs and antibodies that have emerged from our parallel research programmes in small molecule and antibody therapeutics, against human prion strains.


Reviews:

Contribution of transgenic models to understanding human prion disease
Wadsworth JDF, Asante EA, Collinge J.  Neuropathol App Neurobiol 2010; 36: 576-97.


Peer reviewed articles:
2018

Experimental sheep BSE prions generate the vCJD phenotype when serially passaged in transgenic mice expressing human prion protein. Joiner, S., Asante, EA, Linehan, J.M., Brock, L., Brandner, S., Bellworthy, S.J., Simmons, M.M., Hope, J., Collinge, J. and Wadsworth, J.D.F. (2018) J. Neurol. Sci. 386, 4-11.

2017

Protective Effect of Val129-PrP against Bovine Spongiform Encephalopathy but not Variant Creutzfeldt-Jakob Disease. See comment in PubMed Commons belowFernández-Borges N, Espinosa JC, Marín-Moreno A, Aguilar-Calvo P, Asante EA, Kitamoto T, Mohri S, Andréoletti O, Torres JM. Emerg Infect Dis. 2017 Sep; 23(9):1522-1530. doi: 10.3201/eid2309.161948.

2015

Frontotemporal dementia caused by CHMP2B mutation is characterised by neuronal lysosomal storage pathology. Acta Neuropathol
Clayton EL, Mizielinska S, Edgar JR, Nielsen TT, Marshall S, Norona FE, Robbins M, Damirji H, Holm IE, Johannsen P, Nielsen JE, Asante EA, Collinge J; FReJA consortium, Isaacs AM.[Epub ahead of print]; PMID: 26358247

Transmission Properties of Human PrP 102L Prions Challenge the Relevance of Mouse Models of GSS. Asante EA, Grimshaw A, Smidak M, Jakubcova T, Tomlinson A, Jeelani A, Hamdan S, Powell C, Joiner S, Linehan JM, Brandner S, Wadsworth JD, Collinge J

A naturally occurring variant of the human prion protein completely prevents prion disease
Emmanuel A. Asante, Michelle Smidak, Andrew Grimshaw1, Richard Houghton, Andrew Tomlinson, Asif Jeelani, Tatiana Jakubcova, Shyma Hamdan, Angela Richard-Londt, Jacqueline M. Linehan, Sebastian Brandner, Michael Alpers, Jerome Whitfield, Simon Mead, Jonathan D.F. Wadsworth and John Collinge. Nature (2015) doi:10.1038/nature14510.

F1000Prime



2013

Atypical scrapie prions from sheep fail to produce disease in transgenic mice overexpressing human prion protein.
Wadsworth JDF, Joiner S, Linehan JM, Balkema-Buschmann A, Spiropoulos J, Simmons MM, Griffiths PC, Groschup MH, Hope J, Brandner S, Asante EA, Collinge J. Emerg Infect Dis 2013; 19: 1731-39.

Inherited Prion Disease A117V is not simply a proteinopathy but produces prions transmissible to transgenic mice expressing homologous prion protein
Asante EA, Linehan JM, Smidak M, Tomlinson A, Grimshaw A, Jeelani A, Jakubcova T, Hamdan S, O’Malley C, Powell C, Brandner S, Wadsworth JDF, Collinge J.  PLoS Pathog 2013; 9(9): e1003643.

2012

Overexpression of Hspa13 (Stch) reduces prion disease incubation time in mice
Grizenkovaa J, Akhtara S, Hummerich H, Tomlinson A, Asante EA, Wenborn A, Wiseman FK, Fisher EMC, Tybulewiczc VL, Brandner S, Collinge J, Lloyd SE. Proc Natl Acad Sci USA 2012; 109: 13722-7.

Progressive neuronal inclusion formation and axonal degeneration in CHMP2B mutant transgenic mice
Ghazi-Noori S, Froud KE, Mizielinska S, Powell C, Smidak M, Fernandez de Marco M, O'Malley C, Farmer M, Parkinson N, Fisher EM, Asante EA, Brandner S, Collinge J, Isaacs AM.  Brain 2012; 135: 819-32. .

2011

Interaction between cellular prion protein and toxic Aβ oligomers can be therapeutically targeted at multiple sites
Freir DB, Nicoll AJ, Klyubin I, Panico S, Mc Donald JM, Risse E, Asante EA, Farrow -MA, Sessions RB, Saibil HR, Clarke AR, Rowan MJ, Walsh DM Collinge J. Nat Commun 2011; 2: 336

Effect of fixation on brain and lymphoreticular vCJD prions and bioassay of key positive specimens from a retrospective vCJD prevalence study
Wadsworth JDF, Dalmau-Mena I, Joiner S, Linehan J, O'Malley C, Powell C, Brandner S, Asante EA, Ironside JW, Hilton DA, Collinge J.  J Pathol 2011; 223: 511-8.

Threshold for epileptiform activity is elevated in prion knockout mice
Ratte S, Vreugdenhil M, Boult JK, Patel A, Asante EA, Collinge J, Jefferys JG. 
Neuroscience 2011; 179: 56-61.

2010

Chronic wasting disease prions are not transmissible to transgenic mice over-expressing human prion protein
Sandberg MK, Al-Doujaily H, Sigurdson CJ, Glatzel M, O’Malley C, Powell C, Asante EA, Linehan JM, Brandner S, Wadsworth JDF, Collinge J.  J Gen Virol 2010; 91: 2651-7.

2009

Absence of spontaneous disease and comparative prion susceptibility of transgenic mice expressing mutant human prion proteins
Asante EA, Gowland I, Grimshaw A, Linehan JM, Smidak M, Houghton R, Osiguwa O, Tomlinson A, Joiner S, Brandner S, Wadsworth JD, Collinge J.  J Gen Virol 2009; 90: 546-58.


Published abstracts
Inherited Prion Disease A117V produces prions that are transmissible to transgenic mice expressing human PrP 117-Valine
Asante EA, Gowland I, Linehan JM, Smidak M, Brandner S and Collinge J. Prion 2010; 4: PPo3-36,156.