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Hara H, Miyata H, Chida J, Sakaguchi S. Strain-dependent role of copper in prion disease through binding to histidine residues in the N-terminal domain of prion protein. J Neurochem 2023; 167:394-409. [PMID: 37777338 DOI: 10.1111/jnc.15971] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2023] [Revised: 08/28/2023] [Accepted: 09/04/2023] [Indexed: 10/02/2023]
Abstract
The cellular prion protein, PrPC , is a copper-binding protein abundantly expressed in the brain, particularly by neurons, and its conformational conversion into the amyloidogenic isoform, PrPSc , plays a key pathogenic role in prion diseases. However, the role of copper binding to PrPC in prion diseases remains unclear. Here, we fed mice with a low-copper or regular diet and intracerebrally inoculated them with two different mouse-adapted RML scrapie and BSE prions. Mice with a low-copper diet developed disease significantly but only slightly later than those with a regular diet after inoculation with BSE prions, but not with RML prions, suggesting that copper could play a minor role in BSE prion pathogenesis, but not in RML prion pathogenesis. We then generated two lines of transgenic mice expressing mouse PrP with copper-binding histidine (His) residues in the N-terminal domain replaced with alanine residues, termed TgPrP(5H > A)-7342/Prnp0/0 and TgPrP(5H > A)-7524/Prnp0/0 mice, and similarly inoculated RML and BSE prions into them. Due to 2-fold higher expression of PrP(5H > A) than PrPC in wild-type (WT) mice, TgPrP(5H > A)-7524/Prnp0/0 mice were highly susceptible to these prions, compared to WT mice. However, TgPrP(5H > A)-7342/Prnp0/0 mice, which express PrP(5H > A) 1.2-fold as high as PrPC in WT mice, succumbed to disease slightly, but not significantly, later than WT mice after inoculation with RML prions, but significantly so after inoculation with BSE prions. Subsequent secondary inoculation experiments revealed that amino acid sequence differences between PrP(5H > A) and WT PrPSc created no prion transmission barrier to BSE prions. These results suggest that copper-binding His residues in PrPC are dispensable for RML prion pathogenesis but have a minor effect on BSE prion pathogenesis. Taken together, our current results suggest that copper could have a minor effect on prion pathogenesis in a strain-dependent manner through binding to His residues in the N-terminal domain of PrPC .
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Affiliation(s)
- Hideyuki Hara
- Division of Molecular Neurobiology, The Institute for Enzyme Research (KOSOKEN), Tokushima University, Tokushima, Japan
| | - Hironori Miyata
- Animal Research Center, School of Medicine, University of Occupational and Environmental Health, Yahatanishi, Kitakyushu, Japan
| | - Junji Chida
- Division of Molecular Neurobiology, The Institute for Enzyme Research (KOSOKEN), Tokushima University, Tokushima, Japan
| | - Suehiro Sakaguchi
- Division of Molecular Neurobiology, The Institute for Enzyme Research (KOSOKEN), Tokushima University, Tokushima, Japan
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2
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Uchiyama K, Miyata H, Yamaguchi Y, Imamura M, Okazaki M, Pasiana AD, Chida J, Hara H, Atarashi R, Watanabe H, Kondoh G, Sakaguchi S. Strain-Dependent Prion Infection in Mice Expressing Prion Protein with Deletion of Central Residues 91-106. Int J Mol Sci 2020; 21:ijms21197260. [PMID: 33019549 PMCID: PMC7582732 DOI: 10.3390/ijms21197260] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2020] [Revised: 09/23/2020] [Accepted: 09/24/2020] [Indexed: 12/18/2022] Open
Abstract
Conformational conversion of the cellular prion protein, PrPC, into the abnormally folded isoform, PrPSc, is a key pathogenic event in prion diseases. However, the exact conversion mechanism remains largely unknown. Transgenic mice expressing PrP with a deletion of the central residues 91–106 were generated in the absence of endogenous PrPC, designated Tg(PrP∆91–106)/Prnp0/0 mice and intracerebrally inoculated with various prions. Tg(PrP∆91–106)/Prnp0/0 mice were resistant to RML, 22L and FK-1 prions, neither producing PrPSc∆91–106 or prions in the brain nor developing disease after inoculation. However, they remained marginally susceptible to bovine spongiform encephalopathy (BSE) prions, developing disease after elongated incubation times and accumulating PrPSc∆91–106 and prions in the brain after inoculation with BSE prions. Recombinant PrP∆91-104 converted into PrPSc∆91–104 after incubation with BSE-PrPSc-prions but not with RML- and 22L–PrPSc-prions, in a protein misfolding cyclic amplification assay. However, digitonin and heparin stimulated the conversion of PrP∆91–104 into PrPSc∆91–104 even after incubation with RML- and 22L-PrPSc-prions. These results suggest that residues 91–106 or 91–104 of PrPC are crucially involved in prion pathogenesis in a strain-dependent manner and may play a similar role to digitonin and heparin in the conversion of PrPC into PrPSc.
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Affiliation(s)
- Keiji Uchiyama
- Division of Molecular Neurobiology, The Institute for Enzyme Research (KOSOKEN), Tokushima University, 3-18-15 Kuramoto, Tokushima 770-8503, Japan; (K.U.); (Y.Y.); (M.O.); (A.D.P.); (J.C.); (H.H.)
| | - Hironori Miyata
- Animal Research Center, School of Medicine, University of Occupational and Environmental Health, Yahatanishi, Kitakyushu 807-8555, Japan;
| | - Yoshitaka Yamaguchi
- Division of Molecular Neurobiology, The Institute for Enzyme Research (KOSOKEN), Tokushima University, 3-18-15 Kuramoto, Tokushima 770-8503, Japan; (K.U.); (Y.Y.); (M.O.); (A.D.P.); (J.C.); (H.H.)
| | - Morikazu Imamura
- Division of Microbiology, Department of Infectious Diseases, Faculty of Medicine, University of Miyazaki, 5200 Kihara, Kiyotake, Miyazaki 889-1692, Japan; (M.I.); (R.A.)
| | - Mariya Okazaki
- Division of Molecular Neurobiology, The Institute for Enzyme Research (KOSOKEN), Tokushima University, 3-18-15 Kuramoto, Tokushima 770-8503, Japan; (K.U.); (Y.Y.); (M.O.); (A.D.P.); (J.C.); (H.H.)
- Student Laboratory, Tokushima University, Faculty of Medicine, 3-18-15 Kuramoto, Tokushima 770-8503, Japan
| | - Agriani Dini Pasiana
- Division of Molecular Neurobiology, The Institute for Enzyme Research (KOSOKEN), Tokushima University, 3-18-15 Kuramoto, Tokushima 770-8503, Japan; (K.U.); (Y.Y.); (M.O.); (A.D.P.); (J.C.); (H.H.)
| | - Junji Chida
- Division of Molecular Neurobiology, The Institute for Enzyme Research (KOSOKEN), Tokushima University, 3-18-15 Kuramoto, Tokushima 770-8503, Japan; (K.U.); (Y.Y.); (M.O.); (A.D.P.); (J.C.); (H.H.)
| | - Hideyuki Hara
- Division of Molecular Neurobiology, The Institute for Enzyme Research (KOSOKEN), Tokushima University, 3-18-15 Kuramoto, Tokushima 770-8503, Japan; (K.U.); (Y.Y.); (M.O.); (A.D.P.); (J.C.); (H.H.)
| | - Ryuichiro Atarashi
- Division of Microbiology, Department of Infectious Diseases, Faculty of Medicine, University of Miyazaki, 5200 Kihara, Kiyotake, Miyazaki 889-1692, Japan; (M.I.); (R.A.)
| | - Hitomi Watanabe
- Laboratory of Integrative Biological Science, Institute for Frontier Life and Medical Sciences, Kyoto University, Yoshida-Konoe-cho, Sakyo-ku, Kyoto 606-8501, Japan; (H.W.); (G.K.)
| | - Gen Kondoh
- Laboratory of Integrative Biological Science, Institute for Frontier Life and Medical Sciences, Kyoto University, Yoshida-Konoe-cho, Sakyo-ku, Kyoto 606-8501, Japan; (H.W.); (G.K.)
| | - Suehiro Sakaguchi
- Division of Molecular Neurobiology, The Institute for Enzyme Research (KOSOKEN), Tokushima University, 3-18-15 Kuramoto, Tokushima 770-8503, Japan; (K.U.); (Y.Y.); (M.O.); (A.D.P.); (J.C.); (H.H.)
- Correspondence:
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3
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Chida J, Hara H, Uchiyama K, Takahashi E, Miyata H, Kosako H, Tomioka Y, Ito T, Horiuchi H, Matsuda H, Kido H, Sakaguchi S. Prion protein signaling induces M2 macrophage polarization and protects from lethal influenza infection in mice. PLoS Pathog 2020; 16:e1008823. [PMID: 32845931 PMCID: PMC7489546 DOI: 10.1371/journal.ppat.1008823] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2019] [Revised: 09/14/2020] [Accepted: 07/20/2020] [Indexed: 11/18/2022] Open
Abstract
The cellular prion protein, PrPC, is a glycosylphosphatidylinositol anchored-membrane glycoprotein expressed most abundantly in neuronal and to a lesser extent in non-neuronal cells. Its conformational conversion into the amyloidogenic isoform in neurons is a key pathogenic event in prion diseases, including Creutzfeldt-Jakob disease in humans and scrapie and bovine spongiform encephalopathy in animals. However, the normal functions of PrPC remain largely unknown, particularly in non-neuronal cells. Here we show that stimulation of PrPC with anti-PrP monoclonal antibodies (mAbs) protected mice from lethal infection with influenza A viruses (IAVs), with abundant accumulation of anti-inflammatory M2 macrophages with activated Src family kinases (SFKs) in infected lungs. A SFK inhibitor dasatinib inhibited M2 macrophage accumulation in IAV-infected lungs after treatment with anti-PrP mAbs and abolished the anti-PrP mAb-induced protective activity against lethal influenza infection in mice. We also show that stimulation of PrPC with anti-PrP mAbs induced M2 polarization in peritoneal macrophages through SFK activation in vitro and in vivo. These results indicate that PrPC could activate SFK in macrophages and induce macrophage polarization to an anti-inflammatory M2 phenotype after stimulation with anti-PrP mAbs, thereby eliciting protective activity against lethal infection with IAVs in mice after treatment with anti-PrP mAbs. These results also highlight PrPC as a novel therapeutic target for IAV infection.
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Affiliation(s)
- Junji Chida
- Division of Molecular Neurobiology, The Institute for Enzyme Research (KOSOKEN), Tokushima University, Tokushima, Japan
| | - Hideyuki Hara
- Division of Molecular Neurobiology, The Institute for Enzyme Research (KOSOKEN), Tokushima University, Tokushima, Japan
| | - Keiji Uchiyama
- Division of Molecular Neurobiology, The Institute for Enzyme Research (KOSOKEN), Tokushima University, Tokushima, Japan
| | - Etsuhisa Takahashi
- Division of Enzyme Chemistry, The Institute for Enzyme Research, Tokushima University (KOSOKEN), Tokushima, Japan
| | - Hironori Miyata
- Animal Research Center, School of Medicine, University of Occupational and Environmental Health, Kitakyushu, Japan
| | - Hidetaka Kosako
- Division of Cell Signaling, Fujii Memorial Institute of Medical Sciences, Tokushima University, Kuramoto-cho, Tokushima, Japan
| | - Yukiko Tomioka
- Laboratory of Laboratory Animal Science, Joint Department of Veterinary Medicine, Faculty of Agriculture, Tottori University, Tottori, Japan
| | - Toshihiro Ito
- Avian Zoonosis Research Center, Faculty of Agriculture, Tottori University, Koyama-cho, Tottori, Japan
| | - Hiroyuki Horiuchi
- Laboratory of Immunobiology, Graduate School of Integrated Sciences for Life, Hiroshima University, Japan
| | - Haruo Matsuda
- Laboratory of Immunobiology, Department of Molecular and Applied Bioscience, Graduate School of Biosphere Science, Hiroshima University, Japan
| | - Hiroshi Kido
- Division of Enzyme Chemistry, The Institute for Enzyme Research, Tokushima University (KOSOKEN), Tokushima, Japan
| | - Suehiro Sakaguchi
- Division of Molecular Neurobiology, The Institute for Enzyme Research (KOSOKEN), Tokushima University, Tokushima, Japan
- * E-mail:
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Senatore A, Frontzek K, Emmenegger M, Chincisan A, Losa M, Reimann R, Horny G, Guo J, Fels S, Sorce S, Zhu C, George N, Ewert S, Pietzonka T, Hornemann S, Aguzzi A. Protective anti-prion antibodies in human immunoglobulin repertoires. EMBO Mol Med 2020; 12:e12739. [PMID: 32776637 PMCID: PMC7506995 DOI: 10.15252/emmm.202012739] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2020] [Revised: 07/10/2020] [Accepted: 07/10/2020] [Indexed: 01/09/2023] Open
Abstract
Prion immunotherapy may hold great potential, but antibodies against certain PrP epitopes can be neurotoxic. Here, we identified > 6,000 PrP-binding antibodies in a synthetic human Fab phage display library, 49 of which we characterized in detail. Antibodies directed against the flexible tail of PrP conferred neuroprotection against infectious prions. We then mined published repertoires of circulating B cells from healthy humans and found antibodies similar to the protective phage-derived antibodies. When expressed recombinantly, these antibodies exhibited anti-PrP reactivity. Furthermore, we surveyed 48,718 samples from 37,894 hospital patients for the presence of anti-PrP IgGs and found 21 high-titer individuals. The clinical files of these individuals did not reveal any enrichment of specific pathologies, suggesting that anti-PrP autoimmunity is innocuous. The existence of anti-prion antibodies in unbiased human immunological repertoires suggests that they might clear nascent prions early in life. Combined with the reported lack of such antibodies in carriers of disease-associated PRNP mutations, this suggests a link to the low incidence of spontaneous prion diseases in human populations.
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Affiliation(s)
- Assunta Senatore
- Institute of Neuropathology, University of Zurich, Zurich, Switzerland
| | - Karl Frontzek
- Institute of Neuropathology, University of Zurich, Zurich, Switzerland
| | - Marc Emmenegger
- Institute of Neuropathology, University of Zurich, Zurich, Switzerland
| | - Andra Chincisan
- Institute of Neuropathology, University of Zurich, Zurich, Switzerland
| | - Marco Losa
- Institute of Neuropathology, University of Zurich, Zurich, Switzerland
| | - Regina Reimann
- Institute of Neuropathology, University of Zurich, Zurich, Switzerland
| | - Geraldine Horny
- Novartis Institutes for BioMedical Research, Basel, Switzerland
| | - Jingjing Guo
- Institute of Neuropathology, University of Zurich, Zurich, Switzerland
| | - Sylvie Fels
- Novartis Institutes for BioMedical Research, Basel, Switzerland
| | - Silvia Sorce
- Institute of Neuropathology, University of Zurich, Zurich, Switzerland
| | - Caihong Zhu
- Institute of Neuropathology, University of Zurich, Zurich, Switzerland
| | - Nathalie George
- Novartis Institutes for BioMedical Research, Basel, Switzerland
| | - Stefan Ewert
- Novartis Institutes for BioMedical Research, Basel, Switzerland
| | | | - Simone Hornemann
- Institute of Neuropathology, University of Zurich, Zurich, Switzerland
| | - Adriano Aguzzi
- Institute of Neuropathology, University of Zurich, Zurich, Switzerland
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The N-Terminal Polybasic Region of Prion Protein Is Crucial in Prion Pathogenesis Independently of the Octapeptide Repeat Region. Mol Neurobiol 2019; 57:1203-1216. [DOI: 10.1007/s12035-019-01804-5] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2019] [Accepted: 09/26/2019] [Indexed: 10/25/2022]
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6
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Chida J, Sakaguchi S. Cellular prion protein-mediated protection against influenza A virus infection. Future Virol 2019. [DOI: 10.2217/fvl-2018-0146] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The cellular prion protein, termed PrPC, is a glycoprotein abundantly expressed in brains and to a lesser extent in non-neuronal tissues including lungs. It was reported that PrPC is expressed by lung epithelial cells in mice, and that it may play a protective role against lethal infection with influenza A viruses (IAVs). This may occur by regulating Cu content and superoxide dismutase (SOD) activity, eventually reducing oxidative stress in infected lungs. Antioxidative therapeutics have been demonstrated to protect mice from lethal infection with IAVs. Therefore, PrPC might be a new target molecule for development of IAV therapeutics. Here, we introduce the antiviral mechanism of PrPC against IAV infection and discuss perspectives of PrPC-targeting therapeutics against IAV infection.
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Affiliation(s)
- Junji Chida
- Division of Molecular Neurobiology, The Institute for Enzyme Research (KOSOKEN), Tokushima University, 3-18-15 Kuramoto, Tokushima 770-8503, Japan
| | - Suehiro Sakaguchi
- Division of Molecular Neurobiology, The Institute for Enzyme Research (KOSOKEN), Tokushima University, 3-18-15 Kuramoto, Tokushima 770-8503, Japan
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7
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Abstract
The normal cellular prion protein, designated PrPC, is a membrane glycoprotein expressed most abundantly in brains, particularly by neurons, and to a lesser extent in non-neuronal tissues including lungs. Conformational conversion of PrPC into the amyloidogenic isoform is a key pathogenic event in prion diseases. We recently found that PrPC has a protective role against infection with influenza A viruses (IAVs) in mice by reducing reactive oxygen species in the lungs after infection with IAVs. The antioxidative activity of PrPC is probably attributable to its function to activate antioxidative enzyme Cu/Zn-superoxide dismutase, or SOD1, through regulating Cu content in lungs infected with IAVs. Oxidative stress could play a pivotal role in the pathogenesis of a wide range of viral infections. Here, we introduce our and others' studies on the role of PrPC in viral infections, and raise the attractive possibility that PrPC might be a novel target molecule for development of antioxidative therapeutics against not only IAV infection but also other viral infections.
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Affiliation(s)
- Suehiro Sakaguchi
- Division of Molecular Neurobiology, Institute for Enzyme Research (KOSOKEN), Tokushima University , Tokushima, Japan
| | - Junji Chida
- Division of Molecular Neurobiology, Institute for Enzyme Research (KOSOKEN), Tokushima University , Tokushima, Japan
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Chida J, Hara H, Yano M, Uchiyama K, Das NR, Takahashi E, Miyata H, Tomioka Y, Ito T, Kido H, Sakaguchi S. Prion protein protects mice from lethal infection with influenza A viruses. PLoS Pathog 2018; 14:e1007049. [PMID: 29723291 PMCID: PMC5953499 DOI: 10.1371/journal.ppat.1007049] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2017] [Revised: 05/15/2018] [Accepted: 04/23/2018] [Indexed: 11/18/2022] Open
Abstract
The cellular prion protein, designated PrPC, is a membrane glycoprotein expressed abundantly in brains and to a lesser extent in other tissues. Conformational conversion of PrPC into the amyloidogenic isoform is a key pathogenic event in prion diseases. However, the physiological functions of PrPC remain largely unknown, particularly in non-neuronal tissues. Here, we show that PrPC is expressed in lung epithelial cells, including alveolar type 1 and 2 cells and bronchiolar Clara cells. Compared with wild-type (WT) mice, PrPC-null mice (Prnp0/0) were highly susceptible to influenza A viruses (IAVs), with higher mortality. Infected Prnp0/0 lungs were severely injured, with higher inflammation and higher apoptosis of epithelial cells, and contained higher reactive oxygen species (ROS) than control WT lungs. Treatment with a ROS scavenger or an inhibitor of xanthine oxidase (XO), a major ROS-generating enzyme in IAV-infected lungs, rescued Prnp0/0 mice from the lethal infection with IAV. Moreover, Prnp0/0 mice transgenic for PrP with a deletion of the Cu-binding octapeptide repeat (OR) region, Tg(PrPΔOR)/Prnp0/0 mice, were also highly susceptible to IAV infection. These results indicate that PrPC has a protective role against lethal infection with IAVs through the Cu-binding OR region by reducing ROS in infected lungs. Cu content and the activity of anti-oxidant enzyme Cu/Zn-dependent superoxide dismutase, SOD1, were lower in Prnp0/0 and Tg(PrPΔOR)/Prnp0/0 lungs than in WT lungs. It is thus conceivable that PrPC functions to maintain Cu content and regulate SOD1 through the OR region in lungs, thereby reducing ROS in IAV-infected lungs and eventually protecting them from lethal infection with IAVs. Our current results highlight the role of PrPC in protection against IAV infection, and suggest that PrPC might be a novel target molecule for anti-influenza therapeutics. Influenza A virus (IAV) is an enveloped, negative sense, single-stranded RNA virus, causing seasonal epidemic outbreaks of influenza. Anti-influenza agents targeting viral molecules, such as neuraminidase inhibitors, are currently available. However, these agents have accelerated emergence of mutant IAVs that are resistant to these agents among human populations. Development of new types of anti-influenza agents is awaited. We show that the cellular prion protein PrPC has a protective role against lethal infection with IAVs through the octapeptide repeat (OR) region by abrogating lung epithelial cell apoptosis induced by reactive oxygen species (ROS) in infected lungs. We also show that PrPC could reduce ROS in IAV-infected lungs through the OR region by maintaining Cu ion homeostasis and thereby activating Cu/Zn-dependent superoxide dismutase, SOD1. These results highlight the protective role of PrPC in IAV infection. Elucidation of the exact mechanism underlying the PrPC-mediated protection against IAV infection would be important for further understanding the pathogenesis of IAV infection and could be useful for development of new types of anti-influenza therapeutics.
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Affiliation(s)
- Junji Chida
- Division of Molecular Neurobiology, Institute for Enzyme Research (KOSOKEN), Tokushima University, Tokushima, Japan
| | - Hideyuki Hara
- Division of Molecular Neurobiology, Institute for Enzyme Research (KOSOKEN), Tokushima University, Tokushima, Japan
| | - Masashi Yano
- Division of Molecular Neurobiology, Institute for Enzyme Research (KOSOKEN), Tokushima University, Tokushima, Japan
| | - Keiji Uchiyama
- Division of Molecular Neurobiology, Institute for Enzyme Research (KOSOKEN), Tokushima University, Tokushima, Japan
| | - Nandita Rani Das
- Division of Molecular Neurobiology, Institute for Enzyme Research (KOSOKEN), Tokushima University, Tokushima, Japan
| | - Etsuhisa Takahashi
- Division of Enzyme Chemistry, Institute for Enzyme Research, Tokushima University, Tokushima, Japan
| | - Hironori Miyata
- Animal Research Center, School of Medicine, University of Occupational and Environmental Health, Kitakyushu, Japan
| | - Yukiko Tomioka
- Avian Zoonosis Research Center, Faculty of Agriculture, Tottori University, Koyama-cho, Tottori, Japan
| | - Toshihiro Ito
- Avian Zoonosis Research Center, Faculty of Agriculture, Tottori University, Koyama-cho, Tottori, Japan
| | - Hiroshi Kido
- Division of Enzyme Chemistry, Institute for Enzyme Research, Tokushima University, Tokushima, Japan
| | - Suehiro Sakaguchi
- Division of Molecular Neurobiology, Institute for Enzyme Research (KOSOKEN), Tokushima University, Tokushima, Japan
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Prion Protein Devoid of the Octapeptide Repeat Region Delays Bovine Spongiform Encephalopathy Pathogenesis in Mice. J Virol 2017; 92:JVI.01368-17. [PMID: 29046443 DOI: 10.1128/jvi.01368-17] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2017] [Accepted: 10/05/2017] [Indexed: 12/26/2022] Open
Abstract
Conformational conversion of the cellular isoform of prion protein, PrPC, into the abnormally folded, amyloidogenic isoform, PrPSc, is a key pathogenic event in prion diseases, including Creutzfeldt-Jakob disease in humans and scrapie and bovine spongiform encephalopathy (BSE) in animals. We previously reported that the octapeptide repeat (OR) region could be dispensable for converting PrPC into PrPSc after infection with RML prions. We demonstrated that mice transgenically expressing mouse PrP with deletion of the OR region on the PrP knockout background, designated Tg(PrPΔOR)/Prnp0/0 mice, did not show reduced susceptibility to RML scrapie prions, with abundant accumulation of PrPScΔOR in their brains. We show here that Tg(PrPΔOR)/Prnp0/0 mice were highly resistant to BSE prions, developing the disease with markedly elongated incubation times after infection with BSE prions. The conversion of PrPΔOR into PrPScΔOR was markedly delayed in their brains. These results suggest that the OR region may have a crucial role in the conversion of PrPC into PrPSc after infection with BSE prions. However, Tg(PrPΔOR)/Prnp0/0 mice remained susceptible to RML and 22L scrapie prions, developing the disease without elongated incubation times after infection with RML and 22L prions. PrPScΔOR accumulated only slightly less in the brains of RML- or 22L-infected Tg(PrPΔOR)/Prnp0/0 mice than PrPSc in control wild-type mice. Taken together, these results indicate that the OR region of PrPC could play a differential role in the pathogenesis of BSE prions and RML or 22L scrapie prions.IMPORTANCE Structure-function relationship studies of PrPC conformational conversion into PrPSc are worthwhile to understand the mechanism of the conversion of PrPC into PrPSc We show here that, by inoculating Tg(PrPΔOR)/Prnp0/0 mice with the three different strains of RML, 22L, and BSE prions, the OR region could play a differential role in the conversion of PrPC into PrPSc after infection with RML or 22L scrapie prions and BSE prions. PrPΔOR was efficiently converted into PrPScΔOR after infection with RML and 22L prions. However, the conversion of PrPΔOR into PrPScΔOR was markedly delayed after infection with BSE prions. Further investigation into the role of the OR region in the conversion of PrPC into PrPSc after infection with BSE prions might be helpful for understanding the pathogenesis of BSE prions.
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Das NR, Miyata H, Hara H, Uchiyama K, Chida J, Yano M, Watanabe H, Kondoh G, Sakaguchi S. Effects of prion protein devoid of the N-terminal residues 25-50 on prion pathogenesis in mice. Arch Virol 2017; 162:1867-1876. [DOI: 10.1007/s00705-017-3295-3] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2016] [Accepted: 02/02/2017] [Indexed: 12/23/2022]
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11
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Rouget R, Sharma G, LeBlanc AC. Cyclin-dependent kinase 5 phosphorylation of familial prion protein mutants exacerbates conversion into amyloid structure. J Biol Chem 2015; 290:5759-71. [PMID: 25572400 DOI: 10.1074/jbc.m114.630699] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Familial prion protein (PrP) mutants undergo conversion from soluble and protease-sensitive to insoluble and partially protease-resistant proteins. Cyclin-dependent kinase 5 (Cdk5) phosphorylation of wild type PrP (pPrP) at serine 43 induces a conversion of PrP into aggregates and fibrils. Here, we investigated whether familial PrP mutants are predisposed to Cdk5 phosphorylation and whether phosphorylation of familial PrP mutants increases conversion. PrP mutants representing three major familial PrP diseases and different PrP structural domains were studied. We developed a novel in vitro kinase reaction coupled with Thioflavin T binding to amyloid structure assay to monitor phosphorylation-dependent amyloid conversion. Although non-phosphorylated full-length wild type or PrP mutants did not convert into amyloid, Cdk5 phosphorylation rapidly converted these into Thioflavin T-positive structures following first order kinetics. Dephosphorylation partially reversed conversion. Phosphorylation-dependent conversion of PrP from α-helical structures into β-sheet structures was confirmed by circular dichroism. Relative to wild type pPrP, most PrP mutants showed increased rate constants of conversion. In contrast, non-phosphorylated truncated PrP Y145X (where X represents a stop codon) and Q160X mutants converted spontaneously into Thioflavin T-positive fibrils after a lag phase of over 20 h, indicating nucleation-dependent polymerization. Phosphorylation reduced the lag phase by over 50% and thus accelerated the formation of the nucleating event. Consistently, phosphorylated Y145X and phosphorylated Q160X exacerbated conversion in a homologous seeding reaction, whereas WT pPrP could not seed WT PrP. These results demonstrate an influence of both the N terminus and the C terminus of PrP on conversion. We conclude that post-translational modifications of the flexible N terminus of PrP can cause or exacerbate PrP mutant conversion.
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Affiliation(s)
- Raphaël Rouget
- From the Lady Davis Institute for Medical Research, Sir Mortimer B. Davis Jewish General Hospital, Department of Neurology and Neurosurgery, McGill University, Montréal, Québec H3T 1E2, Canada and
| | - Gyanesh Sharma
- From the Lady Davis Institute for Medical Research, Sir Mortimer B. Davis Jewish General Hospital, Department of Neurology and Neurosurgery, McGill University, Montréal, Québec H3T 1E2, Canada and Department of Neurology and Neurosurgery, McGill University, 3775 University Street, Montréal, Québec H3A 2B4, Canada
| | - Andréa C LeBlanc
- From the Lady Davis Institute for Medical Research, Sir Mortimer B. Davis Jewish General Hospital, Department of Neurology and Neurosurgery, McGill University, Montréal, Québec H3T 1E2, Canada and Department of Neurology and Neurosurgery, McGill University, 3775 University Street, Montréal, Québec H3A 2B4, Canada
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Taguchi Y, Mistica AMA, Kitamoto T, Schätzl HM. Critical significance of the region between Helix 1 and 2 for efficient dominant-negative inhibition by conversion-incompetent prion protein. PLoS Pathog 2013; 9:e1003466. [PMID: 23825952 PMCID: PMC3694865 DOI: 10.1371/journal.ppat.1003466] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2013] [Accepted: 05/13/2013] [Indexed: 01/01/2023] Open
Abstract
Prion diseases are fatal infectious neurodegenerative disorders in man and animals associated with the accumulation of the pathogenic isoform PrPSc of the host-encoded prion protein (PrPc). A profound conformational change of PrPc underlies formation of PrPSc and prion propagation involves conversion of PrPc substrate by direct interaction with PrPSc template. Identifying the interfaces and modalities of inter-molecular interactions of PrPs will highly advance our understanding of prion propagation in particular and of prion-like mechanisms in general. To identify the region critical for inter-molecular interactions of PrP, we exploited here dominant-negative inhibition (DNI) effects of conversion-incompetent, internally-deleted PrP (ΔPrP) on co-expressed conversion-competent PrP. We created a series of ΔPrPs with different lengths of deletions in the region between first and second α-helix (H1∼H2) which was recently postulated to be of importance in prion species barrier and PrP fibril formation. As previously reported, ΔPrPs uniformly exhibited aberrant properties including detergent insolubility, limited protease digestion resistance, high-mannose type N-linked glycans, and intracellular localization. Although formerly controversial, we demonstrate here that ΔPrPs have a GPI anchor attached. Surprisingly, despite very similar biochemical and cell-biological properties, DNI efficiencies of ΔPrPs varied significantly, dependant on location and inversely correlated with the size of deletion. This data demonstrates that H1∼H2 and the region C-terminal to it are critically important for efficient DNI. It also suggests that this region is involved in PrP-PrP interaction and conversion of PrPC into PrPSc. To reconcile the paradox of how an intracellular PrP can exert DNI, we demonstrate that ΔPrPs are subject to both proteasomal and lysosomal/autophagic degradation pathways. Using autophagy pathways ΔPrPs obtain access to the locale of prion conversion and PrPSc recycling and can exert DNI there. This shows that the intracellular trafficking of PrPs is more complex than previously anticipated. Prion diseases are deadly infectious diseases of the brain characterized by accumulation of a pathologic protein (PrPSc) which is derived from the normal prion protein (PrPc). Prions replicate by direct contact in a template-directed refolding process which involves conversion of PrPC into PrPSc. Identifying the modalities of this interaction can advance our molecular understanding of prion diseases. Like substrates and competitive inhibitors of enzymes, a conversion-incompetent PrP can inhibit conversion of normal PrPC, a phenomenon known as dominant-negative inhibition (DNI). Interestingly, some conversion-incompetent PrPs efficiently cause DNI but others do not, presumably depending on affinity for PrPSc and integrity of interaction interface. We utilized DNI to characterize the PrP-PrP interaction interface in cultured cells. We created a series of PrPs with internal deletions in the region between helix 1 and 2 and evaluated their DNI. We found an inverse correlation between deletion size and DNI which suggests that this region plays an important role in PrP-PrP interaction. We also found that such PrPs are subject to various cellular degradation pathways and that a fraction of them reaches the intracellular locale of prion conversion. Further investigation of such prion proteins might help elucidating the cellular mechanisms of the PrPC-PrPSc interaction.
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Affiliation(s)
- Yuzuru Taguchi
- Departments of Veterinary Sciences and of Molecular Biology, University of Wyoming, Laramie, Wyoming, United States of America.
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Abstract
Mutations within the central region of prion protein (PrP) have been shown to be associated with severe neurotoxic activity similar to that observed with Dpl, a PrP-like protein. To further investigate this neurotoxic effect, we generated lines of transgenic (Tg) mice expressing three different chimeric PrP-Dpl proteins. Chi1 (amino acids 1-57 of Dpl replaced by amino acids 1-125 of PrP) and Chi2 (amino acids 1-66 of Dpl replaced by amino acids 1-134 of PrP) abrogated the pathogenicity of Dpl indicating that the presence of a N-terminal domain of PrP (23-134) reduced the toxicity of Dpl, as reported. However, when the amino acids 1-24 of Dpl were replaced by amino acids 1-124 of PrP, Chi3 Tg mice, which express the chimeric protein at a very low level, start developing ataxia at the age of 5-7 weeks. This phenotype was not counteracted by a single copy of full-length-PrP(c) but rather by its overexpression, indicating the strong toxicity of the chimeric protein Chi3. Chi3 Tg mice exhibit severe cerebellar atrophy with a significant loss of granule cells. We concluded that aa25 to aa57 of Dpl, which are not present in Chi1 and Chi2 constructs, confer toxicity to the protein. We tested this possibility by using the 25-57 Dpl peptide in primary culture of mouse embryo cortical neurons and found a significant neurotoxic effect. This finding identifies a protein domain that plays a role in mediating Dpl-related toxicity.
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Yamaguchi Y, Miyata H, Uchiyama K, Ootsuyama A, Inubushi S, Mori T, Muramatsu N, Katamine S, Sakaguchi S. Biological and biochemical characterization of mice expressing prion protein devoid of the octapeptide repeat region after infection with prions. PLoS One 2012; 7:e43540. [PMID: 22927985 PMCID: PMC3424169 DOI: 10.1371/journal.pone.0043540] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2012] [Accepted: 07/23/2012] [Indexed: 11/19/2022] Open
Abstract
Accumulating lines of evidence indicate that the N-terminal domain of prion protein (PrP) is involved in prion susceptibility in mice. In this study, to investigate the role of the octapeptide repeat (OR) region alone in the N-terminal domain for the susceptibility and pathogenesis of prion disease, we intracerebrally inoculated RML scrapie prions into tg(PrPΔOR)/Prnp(0/0) mice, which express mouse PrP missing only the OR region on the PrP-null background. Incubation times of these mice were not extended. Protease-resistant PrPΔOR, or PrP(Sc)ΔOR, was easily detectable but lower in the brains of these mice, compared to that in control wild-type mice. Consistently, prion titers were slightly lower and astrogliosis was milder in their brains. However, in their spinal cords, PrP(Sc)ΔOR and prion titers were abundant and astrogliosis was as strong as in control wild-type mice. These results indicate that the role of the OR region in prion susceptibility and pathogenesis of the disease is limited. We also found that the PrP(Sc)ΔOR, including the pre-OR residues 23-50, was unusually protease-resistant, indicating that deletion of the OR region could cause structural changes to the pre-OR region upon prion infection, leading to formation of a protease-resistant structure for the pre-OR region.
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Affiliation(s)
- Yoshitaka Yamaguchi
- Division of Molecular Neurobiology, The Institute for Enzyme Research (KOSOKEN), The University of Tokushima, Tokushima, Japan
- Department of Molecular Microbiology and Immunology, Nagasaki University Graduate School of Biomedical Sciences, Nagasaki, Japan
| | - Hironori Miyata
- Animal Research Center, School of Medicine, University of Occupational and Environmental Health, Kitakyushu, Japan
| | - Keiji Uchiyama
- Division of Molecular Neurobiology, The Institute for Enzyme Research (KOSOKEN), The University of Tokushima, Tokushima, Japan
| | - Akira Ootsuyama
- Department of Radiation Biology and Health, School of Medicine, University of Occupational and Environmental Health, Kitakyushu, Japan
| | - Sachiko Inubushi
- Division of Molecular Neurobiology, The Institute for Enzyme Research (KOSOKEN), The University of Tokushima, Tokushima, Japan
| | - Tsuyoshi Mori
- Division of Molecular Neurobiology, The Institute for Enzyme Research (KOSOKEN), The University of Tokushima, Tokushima, Japan
| | - Naomi Muramatsu
- Division of Molecular Neurobiology, The Institute for Enzyme Research (KOSOKEN), The University of Tokushima, Tokushima, Japan
| | - Shigeru Katamine
- Department of Molecular Microbiology and Immunology, Nagasaki University Graduate School of Biomedical Sciences, Nagasaki, Japan
| | - Suehiro Sakaguchi
- Division of Molecular Neurobiology, The Institute for Enzyme Research (KOSOKEN), The University of Tokushima, Tokushima, Japan
- Department of Molecular Microbiology and Immunology, Nagasaki University Graduate School of Biomedical Sciences, Nagasaki, Japan
- * E-mail:
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Didonna A, Sussman J, Benetti F, Legname G. The role of Bax and caspase-3 in doppel-induced apoptosis of cerebellar granule cells. Prion 2012; 6:309-16. [PMID: 22561161 PMCID: PMC3399532 DOI: 10.4161/pri.20026] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
Doppel (Dpl) protein is a paralog of the prion protein (PrP) that shares 25% sequence similarity with the C-terminus of PrP, a common N-glycosylation site and a C-terminal signal peptide for attachment of a glycosylphophatidyl inositol anchor. Whereas PrPC is highly expressed in the central nervous system (CNS), Dpl is detected mostly in testes and its ectopic expression in the CNS leads to ataxia as well as Purkinje and granule cell degeneration in the cerebellum. The mechanism through which Dpl induces neurotoxicity is still debated. In the present work, primary neuronal cultures derived from postnatal cerebellar granule cells of wild-type and PrP-knockout FVB mice were used in order to investigate the molecular events that occur upon exposure to Dpl. Treatment of cultured cerebellar neurons with recombinant Dpl produced apoptosis that could be prevented by PrP co-incubation. When primary neuronal cultures from Bax-deficient mice were incubated with Dpl, no apoptosis was observed, suggesting an important role of Bax in triggering neurodegeneration. Similarly, cell survival increased when recDpl-treated cells were incubated with an inhibitor of caspase-3, which mediates apoptosis in mammalian cells. Together, our findings raise the possibility that Bax and caspase-3 feature in Dpl-mediated apoptosis.
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Affiliation(s)
- Alessandro Didonna
- Neurobiology Sector, Laboratory of Prion Biology, Scuola Internazionale Superiore di Studi Avanzati (SISSA), Trieste, Italy
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Abstract
Transgenic mice expressing prion protein (PrP) molecules with several different internal deletions display spontaneous neurodegenerative phenotypes that can be dose-dependently suppressed by coexpression of wild-type PrP. Each of these deletions, including the largest one (Δ32-134), retains 9 aa immediately following the signal peptide cleavage site (residues 23-31; KKRPKPGGW). These residues have been implicated in several biological functions of PrP, including endocytic trafficking and binding of glycosaminoglycans. We report here on our experiments to test the role of this domain in the toxicity of deleted forms of PrP. We find that transgenic mice expressing Δ23-134 PrP display no clinical symptoms or neuropathology, in contrast to mice expressing Δ32-134 PrP, suggesting that residues 23-31 are essential for the toxic phenotype. Using a newly developed cell culture assay, we narrow the essential region to amino acids 23-26, and we show that mutant PrP toxicity is not related to the role of the N-terminal residues in endocytosis or binding to endogenous glycosaminoglycans. However, we find that mutant PrP toxicity is potently inhibited by application of exogenous glycosaminoglycans, suggesting that the latter molecules block an essential interaction between the N terminus of PrP and a membrane-associated target site. Our results demonstrate that a short segment containing positively charged amino acids at the N terminus of PrP plays an essential role in mediating PrP-related neurotoxicity. This finding identifies a protein domain that may serve as a drug target for amelioration of prion neurotoxicity.
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Turnbaugh JA, Westergard L, Unterberger U, Biasini E, Harris DA. The N-terminal, polybasic region is critical for prion protein neuroprotective activity. PLoS One 2011; 6:e25675. [PMID: 21980526 PMCID: PMC3183058 DOI: 10.1371/journal.pone.0025675] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2011] [Accepted: 09/09/2011] [Indexed: 11/19/2022] Open
Abstract
Several lines of evidence suggest that the normal form of the prion protein, PrP(C), exerts a neuroprotective activity against cellular stress or toxicity. One of the clearest examples of such activity is the ability of wild-type PrP(C) to suppress the spontaneous neurodegenerative phenotype of transgenic mice expressing a deleted form of PrP (Δ32-134, called F35). To define domains of PrP involved in its neuroprotective activity, we have analyzed the ability of several deletion mutants of PrP (Δ23-31, Δ23-111, and Δ23-134) to rescue the phenotype of Tg(F35) mice. Surprisingly, all of these mutants displayed greatly diminished rescue activity, although Δ23-31 PrP partially suppressed neuronal loss when expressed at very high levels. Our results pinpoint the N-terminal, polybasic domain as a critical determinant of PrP(C) neuroprotective activity, and suggest that identification of molecules interacting with this region will provide important clues regarding the normal function of the protein. Small molecule ligands targeting this region may also represent useful therapeutic agents for treatment of prion diseases.
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Affiliation(s)
- Jessie A. Turnbaugh
- Department of Biochemistry, Boston University School of Medicine, Boston, Massachusetts, United States of America
- Department of Cell Biology and Physiology Washington University School of Medicine St. Louis, St. Louis, Missouri, United States of America
| | - Laura Westergard
- Department of Cell Biology and Physiology Washington University School of Medicine St. Louis, St. Louis, Missouri, United States of America
| | - Ursula Unterberger
- Department of Biochemistry, Boston University School of Medicine, Boston, Massachusetts, United States of America
| | - Emiliano Biasini
- Department of Biochemistry, Boston University School of Medicine, Boston, Massachusetts, United States of America
| | - David A. Harris
- Department of Biochemistry, Boston University School of Medicine, Boston, Massachusetts, United States of America
- * E-mail:
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Westaway D, Daude N, Wohlgemuth S, Harrison P. The PrP-Like Proteins Shadoo and Doppel. Top Curr Chem (Cham) 2011; 305:225-56. [DOI: 10.1007/128_2011_190] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/08/2022]
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19
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La Mendola D, Magrì A, Campagna T, Campitiello MA, Raiola L, Isernia C, Hansson O, Bonomo RP, Rizzarelli E. A doppel alpha-helix peptide fragment mimics the copper(II) interactions with the whole protein. Chemistry 2010; 16:6212-23. [PMID: 20411530 DOI: 10.1002/chem.200902405] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
The doppel protein (Dpl) is the first homologue of the prion protein (PrP(C)) to be discovered; it is overexpressed in transgenic mice that lack the prion gene, resulting in neurotoxicity. The whole prion protein is able to inhibit Dpl neurotoxicity, and its N-terminal domain is the determinant part of the protein function. This region represents the main copper(II) binding site of PrP(C). Dpl is able to bind at least one copper ion, and the specific metal-binding site has been identified as the histidine residue at the beginning of the third helical region. However, a reliable characterization of copper(II) coordination features has not been reported. In a previous paper, we studied the copper(II) interaction with a peptide that encompasses only the loop region potentially involved in metal binding. Nevertheless, we did not find a complete match between the EPR spectroscopic parameters of the copper(II) complexes formed with the synthesized peptide and those reported for the copper(II) binding sites of the whole protein. Herein, the synthesis of the human Dpl peptide fragment hDpl(122-139) (Ac-KPDNKLHQQVLWRLVQEL-NH(2)) and its copper(II) complex species are reported. This peptide encompasses the third alpha helix and part of the loop linking the second and the third helix of human doppel protein. The single-point-mutated peptide, hDpl(122-139)D124N, in which aspartate 124 replaces an asparagine residue, was also synthesized. This peptide was used to highlight the role of the carboxylate group on both the conformation preference of the Dpl fragment and its copper(II) coordination features. NMR spectroscopic measurements show that the hDpl(122-139) peptide fragment is in the prevailing alpha-helix conformation. It is localized within the 127-137 amino acid residue region that represents a reliable conformational mimic of the related protein domain. A comparison with the single-point-mutated hDpl(122-139)D124N reveals the significant role played by the aspartic residue in addressing the peptide conformation towards a helical structure. It is further confirmed by CD measurements. Potentiometric titrations were carried out in aqueous solutions to obtain the stability constant values of the species formed by copper(II) with the hDpl peptides. Spectroscopic studies (EPR, NMR, CD, UV/Vis) were performed to characterize the coordination environments of the different metal complexes. The EPR parameters of the copper(II) complexes with hDpl(122-139) match those of the previously reported copper(II) binding sites of the whole hDpl. Addition of the copper(II) ion to the peptide fragment does not alter the helical conformation of hDpl(122-139), as shown by CD spectra in the far-UV region. The aspartate-driven preorganized secondary structure is not significantly modified by the involvement of Asp124 in the copper(II) complex species that form in the physiological pH range. To elaborate on the potential role of copper(II) in the recently reported interaction between the PrP(C) and Dpl, the affinity of the copper(II) complexes towards the prion N terminus domain and the binding site of Dpl was reported.
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Affiliation(s)
- Diego La Mendola
- Istituto di Biostrutture e Bioimmagini-CNR, c/o Dipartimento di Scienze Chimiche, Viale A. Doria 6, 95125 Catania, Italy
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Solomon IH, Schepker JA, Harris DA. Prion neurotoxicity: insights from prion protein mutants. Curr Issues Mol Biol 2009; 12:51-61. [PMID: 19767650 PMCID: PMC4821541] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/28/2023] Open
Abstract
The chemical nature of prions and the mechanism by which they propagate are now reasonably well understood. In contrast, much less is known about the identity of the toxic prion protein (PrP) species that are responsible for neuronal death, and the cellular pathways that these forms activate. In addition, the normal, physiological function of cellular PrP (PrP(C)) has remained mysterious, hampering efforts to determine whether loss or alteration of this function contributes to the disease phenotype. Considerable evidence now suggests that aggregation, toxicity, and infectivity are distinct properties of PrP that do no necessarily coincide. In this review, we will discuss several mutant forms of PrP that produce spontaneous neurodegeneration in humans and/or transgenic mice without the formation of infectious PrP(Sc). These include an octapeptide insertional mutation, point mutations that favor synthesis of transmembrane forms of PrP, and deletions encompassing the central domain whose neurotoxicity is antagonized by the presence of wild-type PrP. By isolating the neurotoxic effects of PrP from the formation of infectious prions, these mutants have provided important insights into possible pathogenic mechanisms. These studies suggest that prion neurotoxicity may involve subversion of a cytoprotective activity of PrP(C) via altered signaling events at the plasma membrane.
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Affiliation(s)
- Isaac H Solomon
- Department of Cell Biology and Physiology, Washington University School of Medicine, St. Louis, MO 63110, USA
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Functionally relevant domains of the prion protein identified in vivo. PLoS One 2009; 4:e6707. [PMID: 19738901 PMCID: PMC2733036 DOI: 10.1371/journal.pone.0006707] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2009] [Accepted: 07/22/2009] [Indexed: 01/26/2023] Open
Abstract
The prion consists essentially of PrP(Sc), a misfolded and aggregated conformer of the cellular protein PrP(C). Whereas PrP(C) deficient mice are clinically healthy, expression of PrP(C) variants lacking its central domain (PrP(DeltaCD)), or of the PrP-related protein Dpl, induces lethal neurodegenerative syndromes which are repressed by full-length PrP. Here we tested the structural basis of these syndromes by grafting the amino terminus of PrP(C) (residues 1-134), or its central domain (residues 90-134), onto Dpl. Further, we constructed a soluble variant of the neurotoxic PrP(DeltaCD) mutant that lacks its glycosyl phosphatidyl inositol (GPI) membrane anchor. Each of these modifications abrogated the pathogenicity of Dpl and PrP(DeltaCD) in transgenic mice. The PrP-Dpl chimeric molecules, but not anchorless PrP(DeltaCD), ameliorated the disease of mice expressing truncated PrP variants. We conclude that the amino proximal domain of PrP exerts a neurotrophic effect even when grafted onto a distantly related protein, and that GPI-linked membrane anchoring is necessary for both beneficial and deleterious effects of PrP and its variants.
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Abstract
Prion protein (PrP)-like molecule, doppel (Dpl), is neurotoxic in mice, causing Purkinje cell degeneration. In contrast, PrP antagonizes Dpl in trans, rescuing mice from Purkinje cell death. We have previously shown that PrP with deletion of the N-terminal residues 23-88 failed to neutralize Dpl in mice, indicating that the N-terminal region, particularly that including residues 23-88, may have trans-protective activity against Dpl. Interestingly, PrP with deletion elongated to residues 121 or 134 in the N-terminal region was shown to be similarly neurotoxic to Dpl, indicating that the PrP C-terminal region may have toxicity which is normally prevented by the N-terminal domain in cis. We recently investigated further roles for the N-terminal region of PrP in antagonistic interactions with Dpl by producing three different types of transgenic mice. These mice expressed PrP with deletion of residues 25-50 or 51-90, or a fusion protein of the N-terminal region of PrP with Dpl. Here, we discuss a possible model for the antagonistic interaction between PrP and Dpl.
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Affiliation(s)
- Suehiro Sakaguchi
- Division of Molecular Neurobiology, The Institute for Enzyme Research, The University of Tokushima, Tokushima, Japan.
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