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Membrane Domain Localization and Interaction of the Prion-Family Proteins, Prion and Shadoo with Calnexin. MEMBRANES 2021; 11:membranes11120978. [PMID: 34940479 PMCID: PMC8704586 DOI: 10.3390/membranes11120978] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/08/2021] [Revised: 12/06/2021] [Accepted: 12/07/2021] [Indexed: 11/30/2022]
Abstract
The cellular prion protein (PrPC) is renowned for its infectious conformational isoform PrPSc, capable of templating subsequent conversions of healthy PrPCs and thus triggering the group of incurable diseases known as transmissible spongiform encephalopathies. Besides this mechanism not being fully uncovered, the protein’s physiological role is also elusive. PrPC and its newest, less understood paralog Shadoo are glycosylphosphatidylinositol-anchored proteins highly expressed in the central nervous system. While they share some attributes and neuroprotective actions, opposing roles have also been reported for the two; however, the amount of data about their exact functions is lacking. Protein–protein interactions and membrane microdomain localizations are key determinants of protein function. Accurate identification of these functions for a membrane protein, however, can become biased due to interactions occurring during sample processing. To avoid such artifacts, we apply a non-detergent-based membrane-fractionation approach to study the prion protein and Shadoo. We show that the two proteins occupy similarly raft and non-raft membrane fractions when expressed in N2a cells and that both proteins pull down the chaperone calnexin in both rafts and non-rafts. These indicate their possible binding to calnexin in both types of membrane domains, which might be a necessary requisite to aid the inherently unstable native conformation during their lifetime.
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Intrinsic disorder and phase transitions: Pieces in the puzzling role of the prion protein in health and disease. PROGRESS IN MOLECULAR BIOLOGY AND TRANSLATIONAL SCIENCE 2021; 183:1-43. [PMID: 34656326 DOI: 10.1016/bs.pmbts.2021.06.001] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
After four decades of prion protein research, the pressing questions in the literature remain similar to the common existential dilemmas. Who am I? Some structural characteristics of the cellular prion protein (PrPC) and scrapie PrP (PrPSc) remain unknown: there are no high-resolution atomic structures for either full-length endogenous human PrPC or isolated infectious PrPSc particles. Why am I here? It is not known why PrPC and PrPSc are found in specific cellular compartments such as the nucleus; while the physiological functions of PrPC are still being uncovered, the misfolding site remains obscure. Where am I going? The subcellular distribution of PrPC and PrPSc is wide (reported in 10 different locations in the cell). This complexity is further exacerbated by the eight different PrP fragments yielded from conserved proteolytic cleavages and by reversible post-translational modifications, such as glycosylation, phosphorylation, and ubiquitination. Moreover, about 55 pathological mutations and 16 polymorphisms on the PrP gene (PRNP) have been described. Prion diseases also share unique, challenging features: strain phenomenon (associated with the heterogeneity of PrPSc conformations) and the possible transmissibility between species, factors which contribute to PrP undruggability. However, two recent concepts in biochemistry-intrinsically disordered proteins and phase transitions-may shed light on the molecular basis of PrP's role in physiology and disease.
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Proteasomal Inhibition Redirects the PrP-Like Shadoo Protein to the Nucleus. Mol Neurobiol 2019; 56:7888-7904. [PMID: 31129810 PMCID: PMC6815274 DOI: 10.1007/s12035-019-1623-1] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2019] [Accepted: 04/24/2019] [Indexed: 01/08/2023]
Abstract
The Shadoo protein (Sho) exhibits homology to the hydrophobic region of the cellular isoform of prion protein (PrPC). As prion-infected brains gradually accumulate infectivity-associated isoforms of prion protein (PrPSc), levels of mature endogenous Sho become reduced. To study the regulatory effect of the proteostatic network on Sho expression, we investigated the action of lactacystin, MG132, NH4Cl, and 3-methyladenine (3-MA) in two cell culture models. In primary mixed neuronal and glial cell cultures (MNGCs) from transgenic mice expressing wild-type Sho from the PrP gene promoter (Tg.Sprn mice), lactacystin- and MG132-mediated inhibition of proteasomal activity shifted the repertoire of Sho species towards unglycosylated forms appearing in the nuclei; conversely, the autophagic modulators NH4Cl and 3-MA did not affect Sho or PrPC glycosylation patterns. Mouse N2a neuroblastoma cells expressing Sho under control of a housekeeping gene promoter treated with MG132 or lactacystin also showed increased nuclear localization of unglycosylated Sho. As two proteasomal inhibitors tested in two cell paradigms caused redirection of Sho to nuclei at the expense of processing through the secretory pathway, our findings define a balanced shift in subcellular localization that thereby differs from the decreases in net Sho species seen in prion-infected brains. Our data are indicative of a physiological pathway to access Sho functions in the nucleus under conditions of impaired proteasomal activity. We also infer that these conditions would comprise a context wherein Sho’s N-terminal nucleic acid–binding RGG repeat region is brought into play.
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Nyeste A, Stincardini C, Bencsura P, Cerovic M, Biasini E, Welker E. The prion protein family member Shadoo induces spontaneous ionic currents in cultured cells. Sci Rep 2016; 6:36441. [PMID: 27819308 PMCID: PMC5098206 DOI: 10.1038/srep36441] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2016] [Accepted: 10/17/2016] [Indexed: 01/01/2023] Open
Abstract
Some mutant forms of the cellular prion protein (PrPC) carrying artificial deletions or point mutations associated with familial human prion diseases are capable of inducing spontaneous ionic currents across the cell membrane, conferring hypersensitivity to certain antibiotics to a wide range of cultured cells and primary cerebellar granular neurons (CGNs). These effects are abrogated when the wild type (WT) form is co-expressed, suggesting that they might be related to a physiological activity of PrPC. Interestingly, the prion protein family member Shadoo (Sho) makes cells hypersensitive to the same antibiotics as mutant PrP-s, an effect that is diminished by the co-expression of WT-PrP. Here, we report that Sho engages in another mutant PrP-like activity: it spontaneously induces large ionic currents in cultured SH-SY5Y cells, as detected by whole-cell patch clamping. These currents are also decreased by the co-expression of WT-PrP. Furthermore, deletion of the N-terminal (RXXX)8 motif of Sho, mutation of the eight arginine residues of this motif to glutamines, or replacement of the hydrophobic domain by that of PrP, also diminish Sho-induced ionic currents. Our results suggest that the channel activity that is also characteristic to some pathogenic PrP mutants may be linked to a physiological function of Sho.
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Affiliation(s)
- Antal Nyeste
- Institute of Biochemistry, Biological Research Center, Hungarian Academy of Sciences, Szeged, Hungary
- Research Centre for Natural Sciences, Hungarian Academy of Sciences, Budapest, Hungary
| | - Claudia Stincardini
- Dulbecco Telethon Laboratory of Prions and Amyloids, Center for Integrative Biology (CIBIO), University of Trento, 38123 Trento, ITALY
| | - Petra Bencsura
- Research Centre for Natural Sciences, Hungarian Academy of Sciences, Budapest, Hungary
| | - Milica Cerovic
- Department of Neuroscience, Istituto di Ricerche Farmacologiche Mario Negri, 20156 Milano, ITALY
| | - Emiliano Biasini
- Dulbecco Telethon Laboratory of Prions and Amyloids, Center for Integrative Biology (CIBIO), University of Trento, 38123 Trento, ITALY
- Department of Neuroscience, Istituto di Ricerche Farmacologiche Mario Negri, 20156 Milano, ITALY
| | - Ervin Welker
- Institute of Biochemistry, Biological Research Center, Hungarian Academy of Sciences, Szeged, Hungary
- Research Centre for Natural Sciences, Hungarian Academy of Sciences, Budapest, Hungary
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Nyeste A, Bencsura P, Vida I, Hegyi Z, Homolya L, Fodor E, Welker E. Expression of the Prion Protein Family Member Shadoo Causes Drug Hypersensitivity That Is Diminished by the Coexpression of the Wild Type Prion Protein. J Biol Chem 2016; 291:4473-86. [PMID: 26721882 DOI: 10.1074/jbc.m115.679035] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2015] [Indexed: 11/06/2022] Open
Abstract
The prion protein (PrP) seems to exert both neuroprotective and neurotoxic activities. The toxic activities are associated with the C-terminal globular parts in the absence of the flexible N terminus, specifically the hydrophobic domain (HD) or the central region (CR). The wild type prion protein (PrP-WT), having an intact flexible part, exhibits neuroprotective qualities by virtue of diminishing many of the cytotoxic effects of these mutant prion proteins (PrPΔHD and PrPΔCR) when coexpressed. The prion protein family member Doppel, which possesses a three-dimensional fold similar to the C-terminal part of PrP, is also harmful to neuronal and other cells in various models, a phenotype that can also be eliminated by the coexpression of PrP-WT. In contrast, another prion protein family member, Shadoo (Sho), a natively disordered protein possessing structural features similar to the flexible N-terminal tail of PrP, exhibits PrP-WT-like protective properties. Here, we report that, contrary to expectations, Sho expression in SH-SY5Y or HEK293 cells induces the same toxic phenotype of drug hypersensitivity as PrPΔCR. This effect is exhibited in a dose-dependent manner and is also counteracted by the coexpression of PrP-WT. The opposing effects of Shadoo in different model systems revealed here may be explored to help discern the relationship of the various toxic activities of mutant PrPs with each other and the neurotoxic effects seen in neurodegenerative diseases, such as transmissible spongiform encephalopathy and Alzheimer disease.
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Affiliation(s)
- Antal Nyeste
- From the Institute of Biochemistry, Biological Research Center, Hungarian Academy of Sciences, H-6726 Szeged, Hungary
| | - Petra Bencsura
- the Research Centre for Natural Sciences, Hungarian Academy of Sciences, H-1117 Budapest, Hungary, and
| | - István Vida
- the Research Centre for Natural Sciences, Hungarian Academy of Sciences, H-1117 Budapest, Hungary, and the Institute of Chemistry, Eötvös Loránd University, H-1117 Budapest, Hungary
| | - Zoltán Hegyi
- the Research Centre for Natural Sciences, Hungarian Academy of Sciences, H-1117 Budapest, Hungary, and
| | - László Homolya
- the Research Centre for Natural Sciences, Hungarian Academy of Sciences, H-1117 Budapest, Hungary, and
| | - Elfrieda Fodor
- From the Institute of Biochemistry, Biological Research Center, Hungarian Academy of Sciences, H-6726 Szeged, Hungary
| | - Ervin Welker
- From the Institute of Biochemistry, Biological Research Center, Hungarian Academy of Sciences, H-6726 Szeged, Hungary, the Research Centre for Natural Sciences, Hungarian Academy of Sciences, H-1117 Budapest, Hungary, and
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Tóth E, Huszár K, Bencsura P, Kulcsár PI, Vodicska B, Nyeste A, Welker Z, Tóth S, Welker E. Restriction enzyme body doubles and PCR cloning: on the general use of type IIs restriction enzymes for cloning. PLoS One 2014; 9:e90896. [PMID: 24618593 PMCID: PMC3949710 DOI: 10.1371/journal.pone.0090896] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2013] [Accepted: 02/06/2014] [Indexed: 11/25/2022] Open
Abstract
The procedure described here allows the cloning of PCR fragments containing a recognition site of the restriction endonuclease (Type IIP) used for cloning in the sequence of the insert. A Type IIS endonuclease - a Body Double of the Type IIP enzyme - is used to generate the same protruding palindrome. Thus, the insert can be cloned to the Type IIP site of the vector without digesting the PCR product with the same Type IIP enzyme. We achieve this by incorporating the recognition site of a Type IIS restriction enzyme that cleaves the DNA outside of its recognition site in the PCR primer in such a way that the cutting positions straddle the desired overhang sequence. Digestion of the PCR product by the Body Double generates the required overhang. Hitherto the use of Type IIS restriction enzymes in cloning reactions has only been used for special applications, the approach presented here makes Type IIS enzymes as useful as Type IIP enzymes for general cloning purposes. To assist in finding Body Double enzymes, we summarised the available Type IIS enzymes which are potentially useful for Body Double cloning and created an online program (http://group.szbk.u-szeged.hu/welkergr/body_double/index.html) for the selection of suitable Body Double enzymes and the design of the appropriate primers.
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Affiliation(s)
- Eszter Tóth
- Institute of Biochemistry, Biological Research Centre, Hungarian Academy of Sciences, Szeged, Hungary
| | - Krisztina Huszár
- Institute of Molecular Pharmacology, Research Centre for Natural Sciences, Hungarian Academy of Sciences, Budapest, Hungary
| | - Petra Bencsura
- Institute of Molecular Pharmacology, Research Centre for Natural Sciences, Hungarian Academy of Sciences, Budapest, Hungary
| | - Péter István Kulcsár
- Institute of Biochemistry, Biological Research Centre, Hungarian Academy of Sciences, Szeged, Hungary
| | - Barbara Vodicska
- Institute of Biochemistry, Biological Research Centre, Hungarian Academy of Sciences, Szeged, Hungary
| | - Antal Nyeste
- Institute of Biochemistry, Biological Research Centre, Hungarian Academy of Sciences, Szeged, Hungary
| | - Zsombor Welker
- Institute of Molecular Pharmacology, Research Centre for Natural Sciences, Hungarian Academy of Sciences, Budapest, Hungary
| | - Szilvia Tóth
- Institute of Molecular Pharmacology, Research Centre for Natural Sciences, Hungarian Academy of Sciences, Budapest, Hungary
| | - Ervin Welker
- Institute of Biochemistry, Biological Research Centre, Hungarian Academy of Sciences, Szeged, Hungary
- Institute of Molecular Pharmacology, Research Centre for Natural Sciences, Hungarian Academy of Sciences, Budapest, Hungary
- * E-mail:
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