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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

Tg(FFI) and Tg(CJD) neurons show different intracellular PrP accumulations and morphological abnormalities of transport organelles.Cultures of cerebellar granule neurons from non-Tg/Prnp+/+, Tg(FFI-K5+/-)/Prnp0/0 and Tg(CJD-A21+/-)/Prnp0/0 mice were fixed and labeled with anti-PrP monoclonal antibody 12B2 using the gold-enhance protocol. WT PrP is mostly found at the plasma membrane (A). D177N/M128 PrP is mostly in the Golgi (B), and D177N/V128 PrP is mostly in the ER, whose cisternae appear enlarged and swollen (C). Scale bar = 250 nm in A, B and C. (D) Quantification of gold particles in different cell compartments. PM, plasma membrane. (E) Quantification of ER and Golgi volumes of cultured cerebellar granule neurons. Data are the mean ± SD of at least 10 cells per specimen. Data for non-Tg/Prnp+/+ and Tg(CJD-A21+/-) neurons in D and E are from [14].
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ppat.1004796.g011: Tg(FFI) and Tg(CJD) neurons show different intracellular PrP accumulations and morphological abnormalities of transport organelles.Cultures of cerebellar granule neurons from non-Tg/Prnp+/+, Tg(FFI-K5+/-)/Prnp0/0 and Tg(CJD-A21+/-)/Prnp0/0 mice were fixed and labeled with anti-PrP monoclonal antibody 12B2 using the gold-enhance protocol. WT PrP is mostly found at the plasma membrane (A). D177N/M128 PrP is mostly in the Golgi (B), and D177N/V128 PrP is mostly in the ER, whose cisternae appear enlarged and swollen (C). Scale bar = 250 nm in A, B and C. (D) Quantification of gold particles in different cell compartments. PM, plasma membrane. (E) Quantification of ER and Golgi volumes of cultured cerebellar granule neurons. Data are the mean ± SD of at least 10 cells per specimen. Data for non-Tg/Prnp+/+ and Tg(CJD-A21+/-) neurons in D and E are from [14].

Mentions: To see whether the Golgi abnormalities in Tg(FFI) neurons were associated with intracellular accumulation of mutant PrP, we examined primary CGNs by immuno-gold EM using a published procedure [14]. The majority of WT PrP in granule neurons from non-Tg/Prnp+/+ mice localized on the plasma membrane and in endosomes, with only a small fraction in the ER and Golgi (Fig 11A and 11D). In contrast, D177N/M128 PrP localized mostly in the Golgi of Tg(FFI) neurons (~75% vs. ~2.5% in control cells), with far fewer molecules on the plasma membrane (~15% vs. ~85% in controls) (Fig 11B and 11D). The Golgi in these neurons were bigger than controls (Fig 11E). These abnormalities in PrP distribution and intracellular organelle morphology were strikingly different from those of Tg(CJD) neurons, in which we found dramatic swelling of the ER cisternae, with ER retention of mutant PrP (Fig 11C–11E) [14].


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)

Tg(FFI) and Tg(CJD) neurons show different intracellular PrP accumulations and morphological abnormalities of transport organelles.Cultures of cerebellar granule neurons from non-Tg/Prnp+/+, Tg(FFI-K5+/-)/Prnp0/0 and Tg(CJD-A21+/-)/Prnp0/0 mice were fixed and labeled with anti-PrP monoclonal antibody 12B2 using the gold-enhance protocol. WT PrP is mostly found at the plasma membrane (A). D177N/M128 PrP is mostly in the Golgi (B), and D177N/V128 PrP is mostly in the ER, whose cisternae appear enlarged and swollen (C). Scale bar = 250 nm in A, B and C. (D) Quantification of gold particles in different cell compartments. PM, plasma membrane. (E) Quantification of ER and Golgi volumes of cultured cerebellar granule neurons. Data are the mean ± SD of at least 10 cells per specimen. Data for non-Tg/Prnp+/+ and Tg(CJD-A21+/-) neurons in D and E are from [14].
© Copyright Policy
Related In: Results  -  Collection

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getmorefigures.php?uid=PMC4400166&req=5

ppat.1004796.g011: Tg(FFI) and Tg(CJD) neurons show different intracellular PrP accumulations and morphological abnormalities of transport organelles.Cultures of cerebellar granule neurons from non-Tg/Prnp+/+, Tg(FFI-K5+/-)/Prnp0/0 and Tg(CJD-A21+/-)/Prnp0/0 mice were fixed and labeled with anti-PrP monoclonal antibody 12B2 using the gold-enhance protocol. WT PrP is mostly found at the plasma membrane (A). D177N/M128 PrP is mostly in the Golgi (B), and D177N/V128 PrP is mostly in the ER, whose cisternae appear enlarged and swollen (C). Scale bar = 250 nm in A, B and C. (D) Quantification of gold particles in different cell compartments. PM, plasma membrane. (E) Quantification of ER and Golgi volumes of cultured cerebellar granule neurons. Data are the mean ± SD of at least 10 cells per specimen. Data for non-Tg/Prnp+/+ and Tg(CJD-A21+/-) neurons in D and E are from [14].
Mentions: To see whether the Golgi abnormalities in Tg(FFI) neurons were associated with intracellular accumulation of mutant PrP, we examined primary CGNs by immuno-gold EM using a published procedure [14]. The majority of WT PrP in granule neurons from non-Tg/Prnp+/+ mice localized on the plasma membrane and in endosomes, with only a small fraction in the ER and Golgi (Fig 11A and 11D). In contrast, D177N/M128 PrP localized mostly in the Golgi of Tg(FFI) neurons (~75% vs. ~2.5% in control cells), with far fewer molecules on the plasma membrane (~15% vs. ~85% in controls) (Fig 11B and 11D). The Golgi in these neurons were bigger than controls (Fig 11E). These abnormalities in PrP distribution and intracellular organelle morphology were strikingly different from those of Tg(CJD) neurons, in which we found dramatic swelling of the ER cisternae, with ER retention of mutant PrP (Fig 11C–11E) [14].

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