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Transgenic fatal familial insomnia mice indicate prion infectivity-independent mechanisms of pathogenesis and phenotypic expression of disease.

Bouybayoune I, Mantovani S, Del Gallo F, Bertani I, Restelli E, Comerio L, Tapella L, Baracchi F, Fernández-Borges N, Mangieri M, Bisighini C, Beznoussenko GV, Paladini A, Balducci C, Micotti E, Forloni G, Castilla J, Fiordaliso F, Tagliavini F, Imeri L, Chiesa R - PLoS Pathog. (2015)

Bottom Line: However, the mechanism by which misfolded variants of mutant PrP cause different diseases is not known.No prion infectivity was detectable in Tg(FFI) and Tg(CJD) brains by bioassay or protein misfolding cyclic amplification, indicating that mutant PrP has disease-encoding properties that do not depend on its ability to propagate its misfolded conformation.Tg(FFI) and Tg(CJD) neurons have different patterns of intracellular PrP accumulation associated with distinct morphological abnormalities of the endoplasmic reticulum and Golgi, suggesting that mutation-specific alterations of secretory transport may contribute to the disease phenotype.

View Article: PubMed Central - PubMed

Affiliation: Department of Neuroscience, IRCCS-"Mario Negri" Institute for Pharmacological Research, Milan, Italy.

ABSTRACT
Fatal familial insomnia (FFI) and a genetic form of Creutzfeldt-Jakob disease (CJD178) are clinically different prion disorders linked to the D178N prion protein (PrP) mutation. The disease phenotype is determined by the 129 M/V polymorphism on the mutant allele, which is thought to influence D178N PrP misfolding, leading to the formation of distinctive prion strains with specific neurotoxic properties. However, the mechanism by which misfolded variants of mutant PrP cause different diseases is not known. We generated transgenic (Tg) mice expressing the mouse PrP homolog of the FFI mutation. These mice synthesize a misfolded form of mutant PrP in their brains and develop a neurological illness with severe sleep disruption, highly reminiscent of FFI and different from that of analogously generated Tg(CJD) mice modeling CJD178. No prion infectivity was detectable in Tg(FFI) and Tg(CJD) brains by bioassay or protein misfolding cyclic amplification, indicating that mutant PrP has disease-encoding properties that do not depend on its ability to propagate its misfolded conformation. Tg(FFI) and Tg(CJD) neurons have different patterns of intracellular PrP accumulation associated with distinct morphological abnormalities of the endoplasmic reticulum and Golgi, suggesting that mutation-specific alterations of secretory transport may contribute to the disease phenotype.

No MeSH data available.


Related in: MedlinePlus

Ultrastructural abnormalities in Tg(FFI) neurons.(A) Autophagosomes in a hippocampal neuron (arrow) and the surrounding neuropil (arrowheads) of a Tg(FFI-26+/-)/Prnp0/0 mouse at 367 days. (B) Autophagosomes and autophagolysosomes in a dystrophic cerebellar neurite of a Tg(FFI-26+/-)/Prnp+/0 at 444 days. (C) Lipofuscin residual bodies in a thalamic neuron of a Tg(FFI-26+/-)/Prnp0/0 mouse at 367 days. (D) Quantification of lipofuscin residual bodies in the thalamus of three non-Tg and four Tg(FFI) mice aged between 292 and 444 days. Data are the mean ± SD. ****p < 0.0001 by Student’s t test. Values from two non-Tg/Prnp+/+ and one non-Tg/Prnp0/0 mice, and from three Tg(FFI-26+/-)/Prnp0/0 and one Tg(FFI-26+/-)/Prnp+/0 mice were pooled. (E) Normal Golgi appearance in a hippocampal neuron of a non-Tg/Prnp+/+ mouse at 280 days. Onion-like Golgi morphology in hippocampal (F) and thalamic (G) neurons of a Tg(FFI-10+/-)/Prnp0/0 mouse at 331 days. (H, I) Three-dimensional tomography reconstruction from virtual serial slices of the Golgi shown in G. The ER cisterna is colored green (blue arrows). The trans-most cisterna is in the center of the spherical Golgi (blue-green, orange arrows). Medial Golgi cisternae show invaginations of membranes inside their lumen (red arrow in panel I). The cis-most cisterna is not visible in this Golgi stack. Scale bars = 1 μm in A and C, and 0.5 μm in B and E, F and G.
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ppat.1004796.g010: Ultrastructural abnormalities in Tg(FFI) neurons.(A) Autophagosomes in a hippocampal neuron (arrow) and the surrounding neuropil (arrowheads) of a Tg(FFI-26+/-)/Prnp0/0 mouse at 367 days. (B) Autophagosomes and autophagolysosomes in a dystrophic cerebellar neurite of a Tg(FFI-26+/-)/Prnp+/0 at 444 days. (C) Lipofuscin residual bodies in a thalamic neuron of a Tg(FFI-26+/-)/Prnp0/0 mouse at 367 days. (D) Quantification of lipofuscin residual bodies in the thalamus of three non-Tg and four Tg(FFI) mice aged between 292 and 444 days. Data are the mean ± SD. ****p < 0.0001 by Student’s t test. Values from two non-Tg/Prnp+/+ and one non-Tg/Prnp0/0 mice, and from three Tg(FFI-26+/-)/Prnp0/0 and one Tg(FFI-26+/-)/Prnp+/0 mice were pooled. (E) Normal Golgi appearance in a hippocampal neuron of a non-Tg/Prnp+/+ mouse at 280 days. Onion-like Golgi morphology in hippocampal (F) and thalamic (G) neurons of a Tg(FFI-10+/-)/Prnp0/0 mouse at 331 days. (H, I) Three-dimensional tomography reconstruction from virtual serial slices of the Golgi shown in G. The ER cisterna is colored green (blue arrows). The trans-most cisterna is in the center of the spherical Golgi (blue-green, orange arrows). Medial Golgi cisternae show invaginations of membranes inside their lumen (red arrow in panel I). The cis-most cisterna is not visible in this Golgi stack. Scale bars = 1 μm in A and C, and 0.5 μm in B and E, F and G.

Mentions: Electron microscopy (EM) of Tg(FFI) brains detected neuronal ultrastructure abnormalities in several regions, including the neocortex, hippocampus, thalamus and cerebellum. These included autophagosomes, autophagolysosomes and increased amounts of lipofuscin (Fig 10A–10D). The most marked finding, however, was alteration of the Golgi complex, whose cisternae appeared swollen and ‘swirled’, often forming an onion-like structure (Fig 10E–10G). Three-dimensional tomography confirmed the concentric isolated Golgi cisternae and showed invaginations of medial Golgi cisternae inside their lumen (Fig 10H and 10I). These abnormalities were never seen in Tg(WT-E1) and non-Tg controls.


Transgenic fatal familial insomnia mice indicate prion infectivity-independent mechanisms of pathogenesis and phenotypic expression of disease.

Bouybayoune I, Mantovani S, Del Gallo F, Bertani I, Restelli E, Comerio L, Tapella L, Baracchi F, Fernández-Borges N, Mangieri M, Bisighini C, Beznoussenko GV, Paladini A, Balducci C, Micotti E, Forloni G, Castilla J, Fiordaliso F, Tagliavini F, Imeri L, Chiesa R - PLoS Pathog. (2015)

Ultrastructural abnormalities in Tg(FFI) neurons.(A) Autophagosomes in a hippocampal neuron (arrow) and the surrounding neuropil (arrowheads) of a Tg(FFI-26+/-)/Prnp0/0 mouse at 367 days. (B) Autophagosomes and autophagolysosomes in a dystrophic cerebellar neurite of a Tg(FFI-26+/-)/Prnp+/0 at 444 days. (C) Lipofuscin residual bodies in a thalamic neuron of a Tg(FFI-26+/-)/Prnp0/0 mouse at 367 days. (D) Quantification of lipofuscin residual bodies in the thalamus of three non-Tg and four Tg(FFI) mice aged between 292 and 444 days. Data are the mean ± SD. ****p < 0.0001 by Student’s t test. Values from two non-Tg/Prnp+/+ and one non-Tg/Prnp0/0 mice, and from three Tg(FFI-26+/-)/Prnp0/0 and one Tg(FFI-26+/-)/Prnp+/0 mice were pooled. (E) Normal Golgi appearance in a hippocampal neuron of a non-Tg/Prnp+/+ mouse at 280 days. Onion-like Golgi morphology in hippocampal (F) and thalamic (G) neurons of a Tg(FFI-10+/-)/Prnp0/0 mouse at 331 days. (H, I) Three-dimensional tomography reconstruction from virtual serial slices of the Golgi shown in G. The ER cisterna is colored green (blue arrows). The trans-most cisterna is in the center of the spherical Golgi (blue-green, orange arrows). Medial Golgi cisternae show invaginations of membranes inside their lumen (red arrow in panel I). The cis-most cisterna is not visible in this Golgi stack. Scale bars = 1 μm in A and C, and 0.5 μm in B and E, F and G.
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Related In: Results  -  Collection

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Show All Figures
getmorefigures.php?uid=PMC4400166&req=5

ppat.1004796.g010: Ultrastructural abnormalities in Tg(FFI) neurons.(A) Autophagosomes in a hippocampal neuron (arrow) and the surrounding neuropil (arrowheads) of a Tg(FFI-26+/-)/Prnp0/0 mouse at 367 days. (B) Autophagosomes and autophagolysosomes in a dystrophic cerebellar neurite of a Tg(FFI-26+/-)/Prnp+/0 at 444 days. (C) Lipofuscin residual bodies in a thalamic neuron of a Tg(FFI-26+/-)/Prnp0/0 mouse at 367 days. (D) Quantification of lipofuscin residual bodies in the thalamus of three non-Tg and four Tg(FFI) mice aged between 292 and 444 days. Data are the mean ± SD. ****p < 0.0001 by Student’s t test. Values from two non-Tg/Prnp+/+ and one non-Tg/Prnp0/0 mice, and from three Tg(FFI-26+/-)/Prnp0/0 and one Tg(FFI-26+/-)/Prnp+/0 mice were pooled. (E) Normal Golgi appearance in a hippocampal neuron of a non-Tg/Prnp+/+ mouse at 280 days. Onion-like Golgi morphology in hippocampal (F) and thalamic (G) neurons of a Tg(FFI-10+/-)/Prnp0/0 mouse at 331 days. (H, I) Three-dimensional tomography reconstruction from virtual serial slices of the Golgi shown in G. The ER cisterna is colored green (blue arrows). The trans-most cisterna is in the center of the spherical Golgi (blue-green, orange arrows). Medial Golgi cisternae show invaginations of membranes inside their lumen (red arrow in panel I). The cis-most cisterna is not visible in this Golgi stack. Scale bars = 1 μm in A and C, and 0.5 μm in B and E, F and G.
Mentions: Electron microscopy (EM) of Tg(FFI) brains detected neuronal ultrastructure abnormalities in several regions, including the neocortex, hippocampus, thalamus and cerebellum. These included autophagosomes, autophagolysosomes and increased amounts of lipofuscin (Fig 10A–10D). The most marked finding, however, was alteration of the Golgi complex, whose cisternae appeared swollen and ‘swirled’, often forming an onion-like structure (Fig 10E–10G). Three-dimensional tomography confirmed the concentric isolated Golgi cisternae and showed invaginations of medial Golgi cisternae inside their lumen (Fig 10H and 10I). These abnormalities were never seen in Tg(WT-E1) and non-Tg controls.

Bottom Line: However, the mechanism by which misfolded variants of mutant PrP cause different diseases is not known.No prion infectivity was detectable in Tg(FFI) and Tg(CJD) brains by bioassay or protein misfolding cyclic amplification, indicating that mutant PrP has disease-encoding properties that do not depend on its ability to propagate its misfolded conformation.Tg(FFI) and Tg(CJD) neurons have different patterns of intracellular PrP accumulation associated with distinct morphological abnormalities of the endoplasmic reticulum and Golgi, suggesting that mutation-specific alterations of secretory transport may contribute to the disease phenotype.

View Article: PubMed Central - PubMed

Affiliation: Department of Neuroscience, IRCCS-"Mario Negri" Institute for Pharmacological Research, Milan, Italy.

ABSTRACT
Fatal familial insomnia (FFI) and a genetic form of Creutzfeldt-Jakob disease (CJD178) are clinically different prion disorders linked to the D178N prion protein (PrP) mutation. The disease phenotype is determined by the 129 M/V polymorphism on the mutant allele, which is thought to influence D178N PrP misfolding, leading to the formation of distinctive prion strains with specific neurotoxic properties. However, the mechanism by which misfolded variants of mutant PrP cause different diseases is not known. We generated transgenic (Tg) mice expressing the mouse PrP homolog of the FFI mutation. These mice synthesize a misfolded form of mutant PrP in their brains and develop a neurological illness with severe sleep disruption, highly reminiscent of FFI and different from that of analogously generated Tg(CJD) mice modeling CJD178. No prion infectivity was detectable in Tg(FFI) and Tg(CJD) brains by bioassay or protein misfolding cyclic amplification, indicating that mutant PrP has disease-encoding properties that do not depend on its ability to propagate its misfolded conformation. Tg(FFI) and Tg(CJD) neurons have different patterns of intracellular PrP accumulation associated with distinct morphological abnormalities of the endoplasmic reticulum and Golgi, suggesting that mutation-specific alterations of secretory transport may contribute to the disease phenotype.

No MeSH data available.


Related in: MedlinePlus