Prion Protein Glycosylation Is Sensitive to Redox Change

Capellari, Sabina; Zaidi, Syed I. A.; Urig, Cynthia B.; Perry, George; Smith, Mark A.; Petersen, Robert B.

doi:10.1074/jbc.274.49.34846

Cited by 69 publications

(50 citation statements)

References 38 publications

(32 reference statements)

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“…Of these post-translational modifications, glycosylation and disulfide bond formation depend on the cellular redox state (22,27). Impairing the ER oxidative environment or mutating the cysteines yields intracellular, diglycosylated PrP chains lacking the disulfide bond, which resembles the PrP␣3M mutants described here (22,27,30,32). In this work we demonstrated the interplay between oxidative folding and the formation of the toxic CtmPrP.…”

Section: Discussionmentioning

confidence: 99%

“…Indeed, this mutant lacks the intramolecular disulfide bond which is a key determinant for the stability of the ␣2-␣3 subdomain both in vivo and in vitro (22,30,32,51,52).…”

Section: Prp␣3m Mutants Are Highly Toxic In Cultured Cells-tomentioning

confidence: 99%

“…2A). This feature has been described previously for PrP pathogenic mutants with immature glycosylation (6,20,22,25,30,32,46,47). This stimulated us to study the glycosylation of PrP␣3M mutants, focusing on HaPrPDS as a model.…”

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confidence: 99%

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Failure of Prion Protein Oxidative Folding Guides the Formation of Toxic Transmembrane Forms

Lisa

Domingo

Martínez

et al. 2012

Journal of Biological Chemistry

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Background:In vivo folding could play an essential role in prion neurodegenerations. Results: Artificial mutants causing labile PrP folds when expressed in cells originate toxic CtmPrP featured by the absence of the intramolecular disulfide bond. Conclusion: Oxidative folding impairment facilitates the formation of the toxic PrP forms. Significance: Unveiling the mechanism facilitating the formation of toxic PrP forms is crucial for the understanding and prevention of prion disorders.The mechanism by which pathogenic mutations in the globular domain of the cellular prion protein (PrP C ) increase the likelihood of misfolding and predispose to diseases is not yet known. Differences in the evidences provided by structural and metabolic studies of these mutants suggest that in vivo folding could be playing an essential role in their pathogenesis. To address this role, here we use the single or combined M206S and M213S artificial mutants causing labile folds and express them in cells. We find that these mutants are highly toxic, fold as transmembrane PrP, and lack the intramolecular disulfide bond. When the mutations are placed in a chain with impeded transmembrane PrP formation, toxicity is rescued. These results suggest that oxidative folding impairment, as on aging, can be fundamental for the genesis of intracellular neurotoxic intermediates key in prion neurodegenerations.Prion disorders are dominant gain-of-function neurodegenerations whose pathogenesis is linked to misfolded forms of the cellular prion protein (PrP C ), 3 including the prion PrP Sc and the neurotoxic CtmPrP (1-4). PrPSc is an aggregated and proteaseresistant ␤-sheet-enriched conformer of PrP C , which self-perpetuates by the templating the conversion of cell surface PrP C (1, 4). In contrast, CtmPrP is an intracellular transmembrane form generated at the ER with neurotoxic properties (1,5,6). Despite that CtmPrP formation was associated with features of the ER translocation process several pathogenic mutations in the C-terminal domain such as H187R and E200K enhance its levels, suggesting a yet unexplored in vivo interplay between folding and the accumulation and action of this neurotoxic form (6 -8).Since the enunciation of the prion hypothesis, research has focused on the mechanism by which a native PrP C structure reorganizes and acquires self-propagative features like those of PrP Sc (9 -11). The PrP C native state was assigned to the fold adopted by the chain lacking the signal sequences and containing the disulfide bond and used as reference for testing the effect of pathogenic mutations and its conversion into active prions (10,(12)(13)(14)(15)(16). However, the in vivo folding of proteins segregating into the secretory route such as PrP is a complex process participated by the ER folding machinery. This machinery coordinates processing (signal sequences removal, addition of covalent modifications, binding of cofactors, etc.), avoids undesired aggregations, and permits the acquisition of correct structure. This global process involves m...

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Section: Discussionmentioning

confidence: 99%

“…Indeed, this mutant lacks the intramolecular disulfide bond which is a key determinant for the stability of the ␣2-␣3 subdomain both in vivo and in vitro (22,30,32,51,52).…”

Section: Prp␣3m Mutants Are Highly Toxic In Cultured Cells-tomentioning

confidence: 99%

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Failure of Prion Protein Oxidative Folding Guides the Formation of Toxic Transmembrane Forms

Lisa

Domingo

Martínez

et al. 2012

Journal of Biological Chemistry

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“…For example, fluctuations in metal ion concentrations (19,20), glycosylphosphatidylinositol anchor stability (21), extracellular molecules such as glycosaminoglycans (22, 23), pH (24), N-linked glycosylation (18,25), and the redox environment have all been proposed to be implicated (18,26,27). Some of these factors (e.g., variations in pH, posttranslational modifications, or redox environment in the secretory pathway) (13, 17) could also be associated with protein localization or processing within the cell.…”

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confidence: 99%

The interplay of glycosylation and disulfide formation influences fibrillization in a prion protein fragment

Bosques

Imperiali

2003

Proc. Natl. Acad. Sci. U.S.A.

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It is now accepted that the structural transition from cellular prion protein (PrP C ) to proteinase K-resistant prion protein scrapie (PrP Sc ) is the major event leading to transmissible spongiform encephalopathies. Although the mechanism of this transition remains elusive, glycosylation has been proposed to impede the PrP C to PrP Sc conversion. To address the role of glycosylation, we have prepared glycosylated and unglycosylated peptides derived from the 175-195 fragment of the human prion protein. Comparison of the structure, aggregation kinetics, fibril formation capabilities, and redox susceptibility of Cys-179 has shown that the N-linked glycan (at Asn-181) significantly reduces the rate of fibrillization by promoting intermolecular disulfide formation via Cys-179. Furthermore, the aggressive fibrillization of a C179S mutant of this fragment highlights the significant role of disulfide stability in retarding the rate of fibril formation. The implications of these studies are discussed in the context of fibril formation in the intact prion protein.S pongiform encephalopathies are a group of fatal neurodegenerative diseases that can be manifested sporadically, genetically inherited, or in some cases transmitted (1-3). In contrast to many diseases where the nature of the infectious particle is virus or bacterium, currently, the only agent associated with these conditions is the structural isoform of the cellular prion protein (PrP C ) known as the scrapie conformation (PrP Sc ) (1, 4). PrP C is an N-linked glycoprotein that is normally attached to the cell membrane by a glycosylphosphatidylinositol anchor (5). PrP C also contains an intramolecular disulfide bond (Cys179OCys-214) that provides structural stability to the C terminus of the protein (6, 7). Secondary structure analyses have shown that PrP C is a predominantly helical protein, whereas PrP Sc is mainly ␤-sheet, suggesting that the conversion into PrP Sc involves a major structural change (8). Although the structure of the unglycosylated PrP C monomer has been solved by NMR spectroscopy (7, 9), elucidation of the PrP Sc structure has been hampered by its highly aggregated state.As with many membrane-associated proteins, initiation of the biosynthesis of PrP begins with translocation into the endoplasmic reticulum (ER) where the amino-terminal signal sequence is cleaved (1). The ER houses the machinery for asparagine-linked glycosylation as well as for disulfide formation (10, 11). Proteins in the secretory pathway that are misfold in the ER (12, 13) are subject to retrograde transport into the cytosol, where they are degraded by proteasomes (14, 15). In particular, protein isoforms (or mutants) that are less stable during their maturation are most likely to undergo this retrograde transport (14). Lindquist and coworkers have recently shown that inhibition of the proteasome causes PrP to accumulate in the cytosol, where it can adopt a PrP Sc -like conformation (16,17). Furthermore, expression of an unglycosylated, cytosolic form of PrP has extreme...

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“…This is analogous to the binding of copper to the Prp protein [26]. The addition of antioxidants such as SOD and catalase did not inhibit this ability of the A␤PP protein to bind and reduce copper [74].…”

Section: Amyloid-␤ Proteinmentioning

confidence: 94%

Mechanisms by which metals promote events connected to neurodegenerative diseases

Campbell

Smith

Sayre

et al. 2001

Brain Research Bulletin

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Although the exact causative phenomenon responsible for the onset and progression of neurodegenerative disorders is at present unresolved, there are some clues as to the mechanisms underlying these chronic diseases. This review addresses mechanisms by which endogenous or environmental factors, through interaction with redox active metals, may initiate a common cascade of events terminating in neurodegeneration.

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Prion Protein Glycosylation Is Sensitive to Redox Change

Cited by 69 publications

References 38 publications

Failure of Prion Protein Oxidative Folding Guides the Formation of Toxic Transmembrane Forms

Failure of Prion Protein Oxidative Folding Guides the Formation of Toxic Transmembrane Forms

The interplay of glycosylation and disulfide formation influences fibrillization in a prion protein fragment

Mechanisms by which metals promote events connected to neurodegenerative diseases

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