1
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Liu Y, Gu Y, Chen Y, Wang X, Zhou G, Li J, Wang M, Fang S, Yang Y. Translocational attenuation mediated by the PERK-SRP14 axis is a protective mechanism of unfolded protein response. Cell Rep 2024; 43:114402. [PMID: 38943644 DOI: 10.1016/j.celrep.2024.114402] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2022] [Revised: 05/06/2024] [Accepted: 06/11/2024] [Indexed: 07/01/2024] Open
Abstract
The unfolded protein response (UPR) relieves endoplasmic reticulum (ER) stress through multiple strategies, including reducing protein synthesis, increasing protein folding capabilities, and enhancing misfolded protein degradation. After a multi-omics analysis, we find that signal recognition particle 14 (SRP14), an essential component of the SRP, is markedly reduced in cells undergoing ER stress. Further experiments indicate that SRP14 reduction requires PRKR-like ER kinase (PERK)-mediated eukaryotic translation initiation factor 2α (eIF2α) phosphorylation but is independent of ATF4 or ATF3 transcription factors. The decrease of SRP14 correlates with reduced translocation of fusion proteins and endogenous cathepsin D. Enforced expression of an SRP14 variant with elongation arrest capability prevents the reduced translocation of cathepsin D in stressed cells, whereas an SRP14 mutant without the activity does not. Finally, overexpression of SRP14 augments the UPR and aggravates ER-stress-induced cell death. These data suggest that translocational attenuation mediated by the PERK-SRP14 axis is a protective measure for the UPR to mitigate ER stress.
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Affiliation(s)
- Yaofu Liu
- China Regional Research Centre, International Centre for Genetic Engineering and Biotechnology (ICGEB), Taizhou, Jiangsu 225316, China; School of Life Science, Hangzhou Institute for Advanced Study, University of Chinese Academy of Sciences, Hangzhou, Zhejiang 310024, China; Institute of Biochemistry and Cell Biology, Chinese Academy of Sciences, University of Chinese Academy of Sciences, Shanghai 200031, China
| | - Yuexi Gu
- China Regional Research Centre, International Centre for Genetic Engineering and Biotechnology (ICGEB), Taizhou, Jiangsu 225316, China
| | - Ying Chen
- Academy of Pharmacy, Xi'an Jiaotong-Liverpool University, Suzhou, Jiangsu 215123, China
| | - Xuan Wang
- China Regional Research Centre, International Centre for Genetic Engineering and Biotechnology (ICGEB), Taizhou, Jiangsu 225316, China
| | - Guangfeng Zhou
- China Regional Research Centre, International Centre for Genetic Engineering and Biotechnology (ICGEB), Taizhou, Jiangsu 225316, China
| | - Jing Li
- Academy of Pharmacy, Xi'an Jiaotong-Liverpool University, Suzhou, Jiangsu 215123, China
| | - Mu Wang
- Academy of Pharmacy, Xi'an Jiaotong-Liverpool University, Suzhou, Jiangsu 215123, China.
| | - Shengyun Fang
- Center for Biomedical Engineering and Technology, University of Maryland School of Medicine, Baltimore, MD, USA; Department of Physiology, University of Maryland School of Medicine, Baltimore, MD 21201, USA.
| | - Yili Yang
- China Regional Research Centre, International Centre for Genetic Engineering and Biotechnology (ICGEB), Taizhou, Jiangsu 225316, China.
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2
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Banik P, Ray K, Kamps J, Chen QY, Luesch H, Winklhofer KF, Tatzelt J. VCP/p97 mediates nuclear targeting of non-ER-imported prion protein to maintain proteostasis. Life Sci Alliance 2024; 7:e202302456. [PMID: 38570188 PMCID: PMC10992997 DOI: 10.26508/lsa.202302456] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2023] [Revised: 03/27/2024] [Accepted: 03/28/2024] [Indexed: 04/05/2024] Open
Abstract
Mistargeting of secretory proteins in the cytosol can trigger their aggregation and subsequent proteostasis decline. We have identified a VCP/p97-dependent pathway that directs non-ER-imported prion protein (PrP) into the nucleus to prevent the formation of toxic aggregates in the cytosol. Upon impaired translocation into the ER, PrP interacts with VCP/p97, which facilitates nuclear import mediated by importin-ß. Notably, the cytosolic interaction of PrP with VCP/p97 and its nuclear import are independent of ubiquitination. In vitro experiments revealed that VCP/p97 binds non-ubiquitinated PrP and prevents its aggregation. Inhibiting binding of PrP to VCP/p97, or transient proteotoxic stress, promotes the formation of self-perpetuating and partially proteinase resistant PrP aggregates in the cytosol, which compromised cellular proteostasis and disrupted further nuclear targeting of PrP. In the nucleus, RNAs keep PrP in a soluble and non-toxic conformation. Our study revealed a novel ubiquitin-independent role of VCP/p97 in the nuclear targeting of non-imported secretory proteins and highlights the impact of the chemical milieu in triggering protein misfolding.
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Affiliation(s)
- Papiya Banik
- https://ror.org/04tsk2644 Department Biochemistry of Neurodegenerative Diseases, Institute of Biochemistry and Pathobiochemistry, Ruhr University Bochum, Bochum, Germany
| | - Koustav Ray
- https://ror.org/04tsk2644 Department Molecular Cell Biology, Institute of Biochemistry and Pathobiochemistry, Ruhr University Bochum, Bochum, Germany
| | - Janine Kamps
- https://ror.org/04tsk2644 Department Biochemistry of Neurodegenerative Diseases, Institute of Biochemistry and Pathobiochemistry, Ruhr University Bochum, Bochum, Germany
- Cluster of Excellence RESOLV, Bochum, Germany
| | - Qi-Yin Chen
- https://ror.org/02y3ad647 Department of Medicinal Chemistry and Center for Natural Products, Drug Discovery and Development (CNPD3), University of Florida, Gainesville, FL, USA
| | - Hendrik Luesch
- https://ror.org/02y3ad647 Department of Medicinal Chemistry and Center for Natural Products, Drug Discovery and Development (CNPD3), University of Florida, Gainesville, FL, USA
| | - Konstanze F Winklhofer
- https://ror.org/04tsk2644 Department Molecular Cell Biology, Institute of Biochemistry and Pathobiochemistry, Ruhr University Bochum, Bochum, Germany
- Cluster of Excellence RESOLV, Bochum, Germany
| | - Jörg Tatzelt
- https://ror.org/04tsk2644 Department Biochemistry of Neurodegenerative Diseases, Institute of Biochemistry and Pathobiochemistry, Ruhr University Bochum, Bochum, Germany
- Cluster of Excellence RESOLV, Bochum, Germany
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3
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Kryvokhyzha M, Litvinov S, Danchenko M, Khudolieieva L, Kutsokon N, Baráth P, Rashydov N. How does ionizing radiation affect amyloidogenesis in plants? Int J Radiat Biol 2024; 100:922-933. [PMID: 38530837 DOI: 10.1080/09553002.2024.2331126] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2023] [Accepted: 03/07/2024] [Indexed: 03/28/2024]
Abstract
PURPOSE Ionizing radiation is a harsh environmental factor that could induce plant senescence. We hypothesized that radiation-related senescence remodels proteome, particularly by triggering the accumulation of prion-like proteins in plant tissues. The object of this study, pea (Pisum sativum L.), is an agriculturally important legume. Research on the functional importance of amyloidogenic proteins was never performed on this species. MATERIALS AND METHODS Pea seeds were irradiated in the dose range 5-50 Gy of X-rays. Afterward, Fourier-transform infrared spectroscopy (FTIR) was used to investigate changes in the secondary structure of proteins in germinated 3-day-old seedlings. Specifically, we evaluated the ratio between the amide I and II peaks. Next, we performed protein staining with Congo red to compare the presence of amyloids in the samples. In parallel, we profiled the detergent-resistant proteome fraction by ultrahigh-performance liquid chromatography coupled with tandem mass spectrometry (UHPLC-MS). Differentially accumulated proteins were functionally analyzed in MapMan software, and the PLAAC tool was used to predict putative prion-like proteins. RESULTS We showed a reduced germination rate but higher plant height and faster appearance of reproductive organs in the irradiated at dose of 50 Gy group compared with the control; furthermore, we demonstrated more β-sheets and amyloid aggregates in the roots of stressed plants. We detected 531 proteins in detergent-resistant fraction extracted from roots, and 45 were annotated as putative prion-like proteins. Notably, 29 proteins were significantly differentially abundant between the irradiated and the control groups. These proteins belong to several functional categories: amino acid metabolism, carbohydrate metabolism, cytoskeleton organization, regulatory processes, protein biosynthesis, and RNA processing. Thus, the discovery proteomics provided deep data on novel aspects of plant stress biology. CONCLUSION Our data hinted that protein accumulation stimulated seedlings' growth as well as accelerated ontogenesis and, eventually, senescence, primarily through translation and RNA processing. The increased abundance of primary metabolism-related proteins indicates more intensive metabolic processes triggered in germinating pea seeds upon X-ray exposure. The functional role of detected putative amyloidogenic proteins should be validated in overexpression or knockout follow-up studies.
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Affiliation(s)
- Maryna Kryvokhyzha
- Department of Biophysics and Radiobiology, Institute of Cell Biology and Genetic Engineering, National Academy of Sciences of Ukraine, Kyiv, Ukraine
- Institute of Plant Genetics and Biotechnology, Plant Science and Biodiversity Center, Slovak Academy of Sciences, Nitra, Slovakia
| | - Sergii Litvinov
- Department of Biophysics and Radiobiology, Institute of Cell Biology and Genetic Engineering, National Academy of Sciences of Ukraine, Kyiv, Ukraine
| | - Maksym Danchenko
- Institute of Plant Genetics and Biotechnology, Plant Science and Biodiversity Center, Slovak Academy of Sciences, Nitra, Slovakia
| | - Lidiia Khudolieieva
- Department of Biophysics and Radiobiology, Institute of Cell Biology and Genetic Engineering, National Academy of Sciences of Ukraine, Kyiv, Ukraine
| | - Nataliia Kutsokon
- Department of Biophysics and Radiobiology, Institute of Cell Biology and Genetic Engineering, National Academy of Sciences of Ukraine, Kyiv, Ukraine
| | - Peter Baráth
- Department of Glycobiology, Institute of Chemistry, Slovak Academy of Sciences, Bratislava, Slovakia
| | - Namik Rashydov
- Department of Biophysics and Radiobiology, Institute of Cell Biology and Genetic Engineering, National Academy of Sciences of Ukraine, Kyiv, Ukraine
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4
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Polido SA, Stuani C, Voigt A, Banik P, Kamps J, Bader V, Grover P, Krause LJ, Zerr I, Matschke J, Glatzel M, Winklhofer KF, Buratti E, Tatzelt J. Cross-seeding by prion protein inactivates TDP-43. Brain 2024; 147:240-254. [PMID: 37669322 DOI: 10.1093/brain/awad289] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2023] [Revised: 07/14/2023] [Accepted: 08/03/2023] [Indexed: 09/07/2023] Open
Abstract
A common pathological denominator of various neurodegenerative diseases is the accumulation of protein aggregates. Neurotoxic effects are caused by a loss of the physiological activity of the aggregating protein and/or a gain of toxic function of the misfolded protein conformers. In transmissible spongiform encephalopathies or prion diseases, neurodegeneration is caused by aberrantly folded isoforms of the prion protein (PrP). However, it is poorly understood how pathogenic PrP conformers interfere with neuronal viability. Employing in vitro approaches, cell culture, animal models and patients' brain samples, we show that misfolded PrP can induce aggregation and inactivation of TAR DNA-binding protein-43 (TDP-43). Purified PrP aggregates interact with TDP-43 in vitro and in cells and induce the conversion of soluble TDP-43 into non-dynamic protein assemblies. Similarly, mislocalized PrP conformers in the cytosol bind to and sequester TDP-43 in cytosolic aggregates. As a consequence, TDP-43-dependent splicing activity in the nucleus is significantly decreased, leading to altered protein expression in cells with cytosolic PrP aggregates. Finally, we present evidence for cytosolic TDP-43 aggregates in neurons of transgenic flies expressing mammalian PrP and Creutzfeldt-Jakob disease patients. Our study identified a novel mechanism of how aberrant PrP conformers impair physiological pathways by cross-seeding.
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Affiliation(s)
- Stella A Polido
- Department of Biochemistry of Neurodegenerative Diseases, Institute of Biochemistry and Pathobiochemistry, Ruhr University Bochum, 44801 Bochum, Germany
| | - Cristiana Stuani
- International Centre for Genetic Engineering and Biotechnology (ICGEB), 34149 Trieste, Italy
| | - Aaron Voigt
- Department of Neurology, Medical Faculty, University Hospital, RWTH Aachen University, 52074 Aachen, Germany
| | - Papiya Banik
- Department of Biochemistry of Neurodegenerative Diseases, Institute of Biochemistry and Pathobiochemistry, Ruhr University Bochum, 44801 Bochum, Germany
| | - Janine Kamps
- Department of Biochemistry of Neurodegenerative Diseases, Institute of Biochemistry and Pathobiochemistry, Ruhr University Bochum, 44801 Bochum, Germany
- Cluster of Excellence RESOLV, Ruhr University Bochum, 44801 Bochum, Germany
| | - Verian Bader
- Department of Biochemistry of Neurodegenerative Diseases, Institute of Biochemistry and Pathobiochemistry, Ruhr University Bochum, 44801 Bochum, Germany
- Department of Molecular Cell Biology, Institute of Biochemistry and Pathobiochemistry, Ruhr University Bochum, 44801 Bochum, Germany
| | - Prerna Grover
- Department of Biochemistry of Neurodegenerative Diseases, Institute of Biochemistry and Pathobiochemistry, Ruhr University Bochum, 44801 Bochum, Germany
| | - Laura J Krause
- Cluster of Excellence RESOLV, Ruhr University Bochum, 44801 Bochum, Germany
- Department of Molecular Cell Biology, Institute of Biochemistry and Pathobiochemistry, Ruhr University Bochum, 44801 Bochum, Germany
| | - Inga Zerr
- Department of Neurology, University Medical Center Göttingen, 37075 Göttingen, Germany
| | - Jakob Matschke
- Institute of Neuropathology, University Medical Center Hamburg-Eppendorf, 20251 Hamburg, Germany
| | - Markus Glatzel
- Institute of Neuropathology, University Medical Center Hamburg-Eppendorf, 20251 Hamburg, Germany
| | - Konstanze F Winklhofer
- Cluster of Excellence RESOLV, Ruhr University Bochum, 44801 Bochum, Germany
- Department of Molecular Cell Biology, Institute of Biochemistry and Pathobiochemistry, Ruhr University Bochum, 44801 Bochum, Germany
| | - Emanuele Buratti
- International Centre for Genetic Engineering and Biotechnology (ICGEB), 34149 Trieste, Italy
| | - Jörg Tatzelt
- Department of Biochemistry of Neurodegenerative Diseases, Institute of Biochemistry and Pathobiochemistry, Ruhr University Bochum, 44801 Bochum, Germany
- Cluster of Excellence RESOLV, Ruhr University Bochum, 44801 Bochum, Germany
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5
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The E3 Ubiquitin Ligase TRAF6 Interacts with the Cellular Prion Protein and Modulates Its Solubility and Recruitment to Cytoplasmic p62/SQSTM1-Positive Aggresome-Like Structures. Mol Neurobiol 2022; 59:1577-1588. [PMID: 35000151 DOI: 10.1007/s12035-021-02666-6] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2021] [Accepted: 11/25/2021] [Indexed: 10/19/2022]
Abstract
The cellular prion protein (PrPC) is a ubiquitous glycoprotein highly expressed in the brain where it is involved in neurite outgrowth, copper homeostasis, NMDA receptor regulation, cell adhesion, and cell signaling. Conformational conversion of PrPC into its insoluble and aggregation-prone scrapie form (PrPSc) is the trigger for several rare devastating neurodegenerative disorders, collectively referred to as prion diseases. Recent work indicates that the ubiquitin-proteasome system is involved in quality control of PrPC. To better dissect the role of ubiquitination in PrPC physiology, we focused on the E3 RING ubiquitin ligase tumor necrosis factor receptor (TNFR)-associated factor 6 (TRAF6). Here, we report that PrPC interacts with TRAF6 both in vitro, in cells, and in vivo, in the mouse brain. Transient overexpression of TRAF6 indirectly modulates PrPC ubiquitination and triggers redistribution of PrPC into the insoluble fraction. Importantly, in the presence of wild-type TRAF6, but not a mutant lacking E3 ligase activity, PrPC accumulates into cytoplasmic aggresome-like inclusions containing TRAF6 and p62/SQSTM1. Our results suggest that TRAF6 ligase activity could exert a role in the regulation of PrPC redistribution in cells under physiological conditions. This novel interaction may uncover possible mechanisms of cell clearance/reorganization in prion diseases.
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6
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Panes JD, Saavedra P, Pineda B, Escobar K, Cuevas ME, Moraga-Cid G, Fuentealba J, Rivas CI, Rezaei H, Muñoz-Montesino C. PrP C as a Transducer of Physiological and Pathological Signals. Front Mol Neurosci 2021; 14:762918. [PMID: 34880726 PMCID: PMC8648500 DOI: 10.3389/fnmol.2021.762918] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2021] [Accepted: 10/18/2021] [Indexed: 11/13/2022] Open
Abstract
After the discovery of prion phenomenon, the physiological role of the cellular prion protein (PrP C ) remained elusive. In the past decades, molecular and cellular analysis has shed some light regarding interactions and functions of PrP C in health and disease. PrP C , which is located mainly at the plasma membrane of neuronal cells attached by a glycosylphosphatidylinositol (GPI) anchor, can act as a receptor or transducer from external signaling. Although the precise role of PrP C remains elusive, a variety of functions have been proposed for this protein, namely, neuronal excitability and viability. Although many issues must be solved to clearly define the role of PrP C , its connection to the central nervous system (CNS) and to several misfolding-associated diseases makes PrP C an interesting pharmacological target. In a physiological context, several reports have proposed that PrP C modulates synaptic transmission, interacting with various proteins, namely, ion pumps, channels, and metabotropic receptors. PrP C has also been implicated in the pathophysiological cell signaling induced by β-amyloid peptide that leads to synaptic dysfunction in the context of Alzheimer's disease (AD), as a mediator of Aβ-induced cell toxicity. Additionally, it has been implicated in other proteinopathies as well. In this review, we aimed to analyze the role of PrP C as a transducer of physiological and pathological signaling.
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Affiliation(s)
- Jessica D Panes
- Departamento de Fisiología, Facultad de Ciencias Biológicas, Universidad de Concepción, Concepción, Chile
| | - Paulina Saavedra
- Departamento de Fisiología, Facultad de Ciencias Biológicas, Universidad de Concepción, Concepción, Chile.,Departamento de Fisiopatología, Facultad de Ciencias Biológicas, Universidad de Concepción, Concepción, Chile
| | - Benjamin Pineda
- Departamento de Fisiología, Facultad de Ciencias Biológicas, Universidad de Concepción, Concepción, Chile
| | - Kathleen Escobar
- Departamento de Fisiología, Facultad de Ciencias Biológicas, Universidad de Concepción, Concepción, Chile.,Departamento de Fisiopatología, Facultad de Ciencias Biológicas, Universidad de Concepción, Concepción, Chile
| | - Magdalena E Cuevas
- Departamento de Fisiología, Facultad de Ciencias Biológicas, Universidad de Concepción, Concepción, Chile
| | - Gustavo Moraga-Cid
- Departamento de Fisiología, Facultad de Ciencias Biológicas, Universidad de Concepción, Concepción, Chile
| | - Jorge Fuentealba
- Departamento de Fisiología, Facultad de Ciencias Biológicas, Universidad de Concepción, Concepción, Chile
| | - Coralia I Rivas
- Departamento de Fisiopatología, Facultad de Ciencias Biológicas, Universidad de Concepción, Concepción, Chile
| | - Human Rezaei
- Virologie et Immunologie Moléculaires (VIM), Institut National de Recherche pour l'Agriculture, l'Alimentation et l'Environnement (INRAE), Jouy-en-Josas, France.,Université de Versailles Saint-Quentin-en-Yvelines (UVSQ), Versailles, France.,Université Paris-Saclay, Jouy-en-Josas, France
| | - Carola Muñoz-Montesino
- Departamento de Fisiología, Facultad de Ciencias Biológicas, Universidad de Concepción, Concepción, Chile
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7
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Multifunctionality of prostatic acid phosphatase in prostate cancer pathogenesis. Biosci Rep 2021; 41:229977. [PMID: 34677582 PMCID: PMC8536833 DOI: 10.1042/bsr20211646] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2021] [Revised: 09/18/2021] [Accepted: 10/04/2021] [Indexed: 11/24/2022] Open
Abstract
The role of human prostatic acid phosphatase (PAcP, P15309|PPAP_HUMAN) in prostate cancer was investigated using a new proteomics tool termed signal sequence swapping (replacement of domains from the native cleaved amino terminal signal sequence of secretory/membrane proteins with corresponding regions of functionally distinct signal sequence subtypes). This manipulation preferentially redirects proteins to different pathways of biogenesis at the endoplasmic reticulum (ER), magnifying normally difficult to detect subsets of the protein of interest. For PAcP, this technique reveals three forms identical in amino acid sequence but profoundly different in physiological functions, subcellular location, and biochemical properties. These three forms of PAcP can also occur with the wildtype PAcP signal sequence. Clinical specimens from patients with prostate cancer demonstrate that one form, termed PLPAcP, correlates with early prostate cancer. These findings confirm the analytical power of this method, implicate PLPAcP in prostate cancer pathogenesis, and suggest novel anticancer therapeutic strategies.
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8
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Kriegler T, Lang S, Notari L, Hessa T. Prion Protein Translocation Mechanism Revealed by Pulling Force Studies. J Mol Biol 2020; 432:4447-4465. [PMID: 32502491 DOI: 10.1016/j.jmb.2020.05.022] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2020] [Revised: 05/10/2020] [Accepted: 05/28/2020] [Indexed: 11/26/2022]
Abstract
The mammalian prion protein (PrP) engages with the ribosome-Sec61 translocation channel complex to generate different topological variants that are either physiological, or involved in neurodegenerative diseases. Here, we describe cotranslational folding and translocation mechanisms of PrP coupled to an Xbp1-based arrest peptide as folding sensor, to measure forces acting on PrP nascent chain. Our data reveal two main pulling events followed by a minor third one exerted on the nascent chains during their translocation. Using those force landscapes, we show that a specific sequence within an intrinsically disordered region, containing a polybasic and glycine-proline rich residues, modulates the second pulling event by interacting with TRAP complex. This work also delineates the sequence of events involved in generation of PrP toxic transmembrane topologies during its synthesis. Our results shed new insight into the folding of such a topological complex protein, where marginal pulling by the signal sequence, together with the flanking downstream sequence in the mature domain, primarily drives an overall inefficient translocation resulting in the nascent chain to adopt alternative topologies.
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Affiliation(s)
- Theresa Kriegler
- Department of Biochemistry and Biophysics, Arrhenius Laboratories of Natural Sciences, Stockholm University, Svante Arrhenius väg 16C, SE-10691 Stockholm, Sweden
| | - Sven Lang
- Department of Medical Biochemistry and Molecular Biology, Saarland University, Homburg, Germany
| | - Luigi Notari
- Department of Clinical Neuroscience, Therapeutic Immune Design Unit, CMM, L8:02, Karolinska Institutet, Sweden
| | - Tara Hessa
- Department of Biochemistry and Biophysics, Arrhenius Laboratories of Natural Sciences, Stockholm University, Svante Arrhenius väg 16C, SE-10691 Stockholm, Sweden.
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9
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Lee S, Shin Y, Kim K, Song Y, Kim Y, Kang SW. Protein Translocation Acquires Substrate Selectivity Through ER Stress-Induced Reassembly of Translocon Auxiliary Components. Cells 2020; 9:cells9020518. [PMID: 32102453 PMCID: PMC7072789 DOI: 10.3390/cells9020518] [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: 02/06/2020] [Revised: 02/20/2020] [Accepted: 02/24/2020] [Indexed: 11/16/2022] Open
Abstract
Protein import across the endoplasmic reticulum membrane is physiologically regulated in a substrate-selective manner to ensure the protection of stressed ER from the overload of misfolded proteins. However, it is poorly understood how different types of substrates are accurately distinguished and disqualified during translocational regulation. In this study, we found poorly assembled translocon-associated protein (TRAP) complexes in stressed ER. Immunoaffinity purification identified calnexin in the TRAP complex in which poor assembly inhibited membrane insertion of the prion protein (PrP) in a transmembrane sequence-selective manner, through translocational regulation. This reaction was induced selectively by redox perturbation, rather than calcium depletion, in the ER. The liberation of ERp57 from calnexin appeared to be the reason for the redox sensitivity. Stress-independent disruption of the TRAP complex prevented a pathogenic transmembrane form of PrP (ctmPrP) from accumulating in the ER. This study uncovered a previously unappreciated role for calnexin in assisting the redox-sensitive function of the TRAP complex and provided insights into the ER stress-induced reassembly of translocon auxiliary components as a key mechanism by which protein translocation acquires substrate selectivity.
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Affiliation(s)
- Sohee Lee
- Department of Biomedical Sciences, University of Ulsan College of Medicine, Seoul 138-736, Korea; (S.L.); (Y.S.); (Y.S.)
- Asan Medical Institute of Convergence Science and Technology, Asan Medical Center, Seoul 05505, Korea
| | - Yejin Shin
- Department of Biomedical Sciences, University of Ulsan College of Medicine, Seoul 138-736, Korea; (S.L.); (Y.S.); (Y.S.)
- Asan Medical Institute of Convergence Science and Technology, Asan Medical Center, Seoul 05505, Korea
| | - Kyunggon Kim
- Department of Convergence Medicine, Asan Medical Center, Seoul 05505, Korea;
| | - Youngsup Song
- Department of Biomedical Sciences, University of Ulsan College of Medicine, Seoul 138-736, Korea; (S.L.); (Y.S.); (Y.S.)
- Asan Medical Institute of Convergence Science and Technology, Asan Medical Center, Seoul 05505, Korea
| | - Yongsub Kim
- Department of Biomedical Sciences, University of Ulsan College of Medicine, Seoul 138-736, Korea; (S.L.); (Y.S.); (Y.S.)
- Asan Medical Institute of Convergence Science and Technology, Asan Medical Center, Seoul 05505, Korea
| | - Sang-Wook Kang
- Department of Biomedical Sciences, University of Ulsan College of Medicine, Seoul 138-736, Korea; (S.L.); (Y.S.); (Y.S.)
- Asan Medical Institute of Convergence Science and Technology, Asan Medical Center, Seoul 05505, Korea
- Correspondence: ; Tel.: +82-2-3010-2205
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10
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Lee Y, Eum H, Lee D, Lee S, Song Y, Kang SW. Mutant-selective topologic conversion facilitates selective degradation of a pathogenic prion isoform. Cell Death Differ 2019; 27:284-296. [PMID: 31127199 PMCID: PMC7205900 DOI: 10.1038/s41418-019-0354-1] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2018] [Revised: 04/10/2019] [Accepted: 05/13/2019] [Indexed: 11/29/2022] Open
Abstract
Regulating protein import across the endoplasmic reticulum (ER) membrane occasionally results in the synthesis of topologically unnatural variants, and their accumulation often leads to proteotoxicity. However, since this is a regulated process, it is questionable whether the topological rearrangement really has adverse consequences. In the present study, we provide an insight into the functional benefit of translocational regulation by illustrating mutant-selective topologic conversion (MSTC) and demonstrate that MSTC contributes to selective degradation of a membrane-anchored prion protein isoform (ctmPrP). We find that ctmPrP is inherently short-lived and topologically competent for degradation rather than accumulation. MSTC achieves, cotranslationally, the unique topology of ctmPrP during translocation, facilitating selective ctmPrP degradation from the ER via the proteasome-dependent pathway before entering the secretory pathway. At this time, the N-terminal polycationic cluster is essential for MSTC, and its cytosolic exposure acquires “ERAD-degron”-like activity for ctmPrP. Bypassing MSTC delays ctmPrP degradation, thus increasing prion proteotoxicity. Thus, topological rearrangement is used for the MSTC as a part of the protein quality control pathway to ensure the safety of the secretory pathway from misfolded PrP.
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Affiliation(s)
- Yumi Lee
- Department of Biomedical Sciences, University of Ulsan College of Medicine, Seoul, Republic of Korea
| | - Hongsik Eum
- Department of Biomedical Sciences, University of Ulsan College of Medicine, Seoul, Republic of Korea
| | - Duri Lee
- Department of Biomedical Sciences, University of Ulsan College of Medicine, Seoul, Republic of Korea
| | - Sohee Lee
- Department of Biomedical Sciences, University of Ulsan College of Medicine, Seoul, Republic of Korea
| | - Youngsup Song
- Department of Biomedical Sciences, University of Ulsan College of Medicine, Seoul, Republic of Korea.,Asan Institute of Life Sciences, Asan Medical Center, Seoul, Republic of Korea
| | - Sang-Wook Kang
- Department of Biomedical Sciences, University of Ulsan College of Medicine, Seoul, Republic of Korea. .,Asan Institute of Life Sciences, Asan Medical Center, Seoul, Republic of Korea.
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11
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The VCP-UBXN1 Complex Mediates Triage of Ubiquitylated Cytosolic Proteins Bound to the BAG6 Complex. Mol Cell Biol 2018; 38:MCB.00154-18. [PMID: 29685906 DOI: 10.1128/mcb.00154-18] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2018] [Accepted: 04/04/2018] [Indexed: 12/13/2022] Open
Abstract
A balance between protein synthesis and degradation is necessary to maintain cellular homeostasis. Failure to triage aberrant proteins may result in their accumulation and aggregation in the cytosol. The valosin-containing protein (VCP)-BCL2-associated athanogene 6 (BAG6) complex facilitates a wide variety of ubiquitin-mediated quality control events at the endoplasmic reticulum (ER), both prior to ER translocation and during ER-associated degradation (ERAD). However, how ubiquitylated clients associated with BAG6 are recognized by VCP for proteasomal degradation is presently unknown. We have identified UBXN1 as the VCP adaptor in BAG6-dependent processes occurring prior to ER insertion but not during ERAD. The loss of VCP-UBXN1 results in the inappropriate stabilization of ubiquitylated BAG6 clients and their accumulation in insoluble aggregates and sensitizes cells to proteotoxic stress. Our results identify how VCP is specifically targeted to ubiquitylated substrates in the BAG6 triage pathway and suggest that the degradation of ubiquitylated clients by the proteasome is reliant on the association of UBXN1 with ubiquitylated substrates and the catalytic activity of VCP.
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12
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Majumder P, Chakrabarti O. Lysosomal Quality Control in Prion Diseases. Mol Neurobiol 2017; 55:2631-2644. [PMID: 28421536 DOI: 10.1007/s12035-017-0512-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2016] [Accepted: 04/04/2017] [Indexed: 11/28/2022]
Abstract
Prion diseases are transmissible, familial or sporadic. The prion protein (PrP), a normal cell surface glycoprotein, is ubiquitously expressed throughout the body. While loss of function of PrP does not elicit apparent phenotypes, generation of misfolded forms of the protein or its aberrant metabolic isoforms has been implicated in a number of neurodegenerative disorders such as scrapie, kuru, Creutzfeldt-Jakob disease, fatal familial insomnia, Gerstmann-Sträussler-Scheinker and bovine spongiform encephalopathy. These diseases are all phenotypically characterised by spongiform vacuolation of the adult brain, hence collectively termed as late-onset spongiform neurodegeneration. Misfolded form of PrP (PrPSc) and one of its abnormal metabolic isoforms (the transmembrane CtmPrP) are known to be disease-causing agents that lead to progressive loss of structure or function of neurons culminating in neuronal death. The aberrant forms of PrP utilise and manipulate the various intracellular quality control mechanisms during pathogenesis of these diseases. Amongst these, the lysosomal quality control machinery emerges as one of the primary targets exploited by the disease-causing isoforms of PrP. The autophagosomal-lysosomal degradation pathway is adversely affected in multiple ways in prion diseases and may hence be regarded as an important modulator of neurodegeneration. Some of the ESCRT pathway proteins have also been shown to be involved in the manifestation of disease phenotype. This review discusses the significance of the lysosomal quality control pathway in affecting transmissible and familial types of prion diseases.
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Affiliation(s)
- Priyanka Majumder
- Biophysics and Structural Genomics Division, Saha Institute of Nuclear Physics, Sector-1, Block-AF, Bidhannagar, Kolkata, West Bengal, 700064, India
| | - Oishee Chakrabarti
- Biophysics and Structural Genomics Division, Saha Institute of Nuclear Physics, Sector-1, Block-AF, Bidhannagar, Kolkata, West Bengal, 700064, India.
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13
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Mays CE, Soto C. The stress of prion disease. Brain Res 2016; 1648:553-560. [PMID: 27060771 DOI: 10.1016/j.brainres.2016.04.009] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2016] [Revised: 04/01/2016] [Accepted: 04/05/2016] [Indexed: 01/31/2023]
Abstract
Prion diseases are fatal neurodegenerative disorders that include scrapie of sheep, bovine spongiform encephalopathy of cattle, chronic wasting disease of cervids, and Creutzfeldt-Jakob disease (CJD) of humans. The etiology for prion diseases can be infectious, sporadic, or hereditary. However, the common denominator for all types is the formation of a transmissible agent composed of a β-sheet-rich, misfolded version of the host-encoded prion protein (PrPC), known as PrPSc. PrPSc self-replicates through a template-assisted process that converts the α-helical conformation of PrPC into the disease-associated isoform. In parallel with PrPSc accumulation, spongiform change is pathologically observed in the central nervous system, where "holes" appear because of massive neuronal death. Here, we review the cellular pathways triggered in response to PrPSc formation and accumulation. Available data suggest that neuronal dysfunction and death may be caused by what originates as a cellular pro-survival response to chronic PrPSc accumulation. We also discuss what is known about the complex cross-talk between the endoplasmic reticulum stress components and the quality control pathways. Better knowledge about these processes may lead to innovative therapeutic strategies based on manipulating the stress response and its consequences for neurodegeneration. This article is part of a Special Issue entitled SI:ER stress.
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Affiliation(s)
- Charles E Mays
- Mitchell Center for Alzheimer's Disease and Related Brain Disorders, Department of Neurology, University of Texas Houston Medical School, Houston, TX 77030, USA
| | - Claudio Soto
- Mitchell Center for Alzheimer's Disease and Related Brain Disorders, Department of Neurology, University of Texas Houston Medical School, Houston, TX 77030, USA.
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14
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Lee Y, Lee D, Choi I, Song Y, Kang MJ, Kang SW. Single octapeptide deletion selectively processes a pathogenic prion protein mutant on the cell surface. Biochem Biophys Res Commun 2016; 470:263-268. [PMID: 26774341 DOI: 10.1016/j.bbrc.2016.01.074] [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: 01/02/2016] [Accepted: 01/12/2016] [Indexed: 11/30/2022]
Abstract
The number of octapeptide repeats has been considered to correlate with clinical and pathogenic phenotypes of prion diseases resulting from aberrant metabolism of prion protein (PrP). However, it is still poorly understood how this motif affects PrP metabolism. Here, we discover homozygous single octapeptide repeat deletion mutation in the PRNP gene encoding PrP in HeLa cells. The level of PrP proves to be unaffected by this mutation alone, but selectively reduced by additional pathogenic mutations within internal hydrophobic region of PrP. The pattern and relative amount of newly synthesized A117V mutant is unaffected, whereas the mutant appears to be differentially distributed and processed on the cell surface by single octapeptide deletion. This study provides an insight into a novel mutant-specific metabolism of PrP on the cell surface.
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Affiliation(s)
- Yumi Lee
- Department of Biomedical Sciences, University of Ulsan College of Medicine & Asan Institute of Life Sciences, Asan Medical Center, Seoul, Republic of Korea
| | - Duri Lee
- Department of Biomedical Sciences, University of Ulsan College of Medicine & Asan Institute of Life Sciences, Asan Medical Center, Seoul, Republic of Korea
| | - Ilho Choi
- Department of Biomedical Sciences, University of Ulsan College of Medicine & Asan Institute of Life Sciences, Asan Medical Center, Seoul, Republic of Korea
| | - Youngsup Song
- Department of Biomedical Sciences, University of Ulsan College of Medicine & Asan Institute of Life Sciences, Asan Medical Center, Seoul, Republic of Korea
| | - Min-Ji Kang
- Department of Biomedical Sciences, University of Ulsan College of Medicine & Asan Institute of Life Sciences, Asan Medical Center, Seoul, Republic of Korea
| | - Sang-Wook Kang
- Department of Biomedical Sciences, University of Ulsan College of Medicine & Asan Institute of Life Sciences, Asan Medical Center, Seoul, Republic of Korea.
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15
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Stabilization of microtubular cytoskeleton protects neurons from toxicity of N-terminal fragment of cytosolic prion protein. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2015; 1853:2228-39. [DOI: 10.1016/j.bbamcr.2015.07.002] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/12/2015] [Revised: 06/12/2015] [Accepted: 07/03/2015] [Indexed: 11/19/2022]
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16
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Martínez J, Sánchez R, Castellanos M, Makarava N, Aguzzi A, Baskakov IV, Gasset M. PrP charge structure encodes interdomain interactions. Sci Rep 2015; 5:13623. [PMID: 26323476 PMCID: PMC4555102 DOI: 10.1038/srep13623] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2015] [Accepted: 07/31/2015] [Indexed: 11/19/2022] Open
Abstract
Almost all proteins contain charged residues, and their chain distribution is tailored to fulfill essential ionic interactions for folding, binding and catalysis. Among proteins, the hinged two-domain chain of the cellular prion protein (PrPC) exhibits a peculiar charge structure with unclear consequences in its structural malleability. To decipher the charge design role, we generated charge-reverted mutants for each domain and analyzed their effect on conformational and metabolic features. We found that charges contain the information for interdomain interactions. Use of dynamic light scattering and thermal denaturation experiments delineates the compaction of the α-fold by an electrostatic compensation between the polybasic 23–30 region and the α3 electronegative surface. This interaction increases stability and disfavors fibrillation. Independently of this structural effect, the N-terminal electropositive clusters regulate the α-cleavage efficiency. In the fibrillar state, use of circular dichroism, atomic-force and fluorescence microscopies reveal that the N-terminal positive clusters and the α3 electronegative surface dictate the secondary structure, the assembly hierarchy and the growth length of the fibril state. These findings show that the PrP charge structure functions as a code set up to ensure function and reduce pathogenic routes.
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Affiliation(s)
- Javier Martínez
- Instituto Química-Física "Rocasolano", Consejo Superior de Investigaciones Científicas, Madrid 28006, Spain
| | - Rosa Sánchez
- Instituto Química-Física "Rocasolano", Consejo Superior de Investigaciones Científicas, Madrid 28006, Spain
| | - Milagros Castellanos
- Centro Nacional de Biotecnología, Consejo Superior de Investigaciones Científicas, Madrid, Spain; IMDEA-Nanociencia, Madrid 28049, Spain
| | - Natallia Makarava
- Center for Biomedical Engineering and Technology, University of Maryland School of Medicine, Baltimore, MD 21201, USA
| | - Adriano Aguzzi
- Institute of Neuropathology, University Hospital of Zürich, Zürich 8091, Switzerland
| | - Ilia V Baskakov
- Center for Biomedical Engineering and Technology, University of Maryland School of Medicine, Baltimore, MD 21201, USA
| | - María Gasset
- Instituto Química-Física "Rocasolano", Consejo Superior de Investigaciones Científicas, Madrid 28006, Spain
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17
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Zhao H, Du Y, Chen S, Qing L, Wang X, Huang J, Wu D, Zhang Y. The prion protein gene polymorphisms associated with bovine spongiform encephalopathy susceptibility differ significantly between cattle and buffalo. INFECTION GENETICS AND EVOLUTION 2015; 36:531-538. [PMID: 26319996 DOI: 10.1016/j.meegid.2015.08.031] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/23/2015] [Revised: 08/19/2015] [Accepted: 08/24/2015] [Indexed: 10/23/2022]
Abstract
Prion protein, encoded by the prion protein gene (PRNP), plays a crucial role in the pathogenesis of transmissible spongiform encephalopathies (TSEs). Several polymorphisms within the PRNP are known to be associated with influencing bovine spongiform encephalopathy (BSE) susceptibility in cattle, namely two insertion/deletion (indel) polymorphisms (a 23-bp indel in the putative promoter and a 12-bp indel in intron 1), the number of octapeptide repeats (octarepeats) present in coding sequence (CDS) and amino acid polymorphisms. The domestic buffaloes, Bubalus bubalis, are a ruminant involved in various aspects of agriculture. It is of interest to ask whether the PRNP polymorphisms differ between cattle and buffalo. In this study, we analyzed the previously reported polymorphisms associated with BSE susceptibility in Chinese buffalo breeds, and compared these polymorphisms in cattle with BSE, healthy cattle and buffalo by pooling data from the literature. Our analysis revealed three significant findings in buffalo: 1) extraordinarily low deletion allele frequencies of the 23- and 12-bp indel polymorphisms; 2) significantly low allelic frequencies of six octarepeats in CDS and 3) the presence of S4R, A16V, P54S, G108S, V123M, S154N and F257L substitutions in buffalo CDSs. Sequence alignments comparing the buffalo coding sequence to other species were analyzed using the McDonald-Kreitman test to reveal five groups (Bison bonasus, Bos indicus, Bos gaurus, Boselaphus tragocamelus, Syncerus caffer caffer) with significantly divergent non-synonymous substitutions from buffalo, suggesting potential divergence of buffalo PRNP and others. To the best of our knowledge this is the first study of PRNP polymorphisms associated with BSE susceptibility in Chinese buffalo. Our findings have provided evidence that buffaloes have a unique genetic background in the PRNP gene in comparison with cattle.
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Affiliation(s)
- Hui Zhao
- Laboratory for Conservation and Utilization of Bio-resource, Yunnan University, Kunming 650091, China
| | - Yanli Du
- Laboratory for Conservation and Utilization of Bio-resource, Yunnan University, Kunming 650091, China
| | - Shunmei Chen
- State Key Laboratory of Genetic Resources and Evolution, Kunming Institute of Zoology, Chinese Academy of Sciences, Kunming 650223, China
| | - Lili Qing
- Laboratory for Conservation and Utilization of Bio-resource, Yunnan University, Kunming 650091, China
| | - Xiaoyan Wang
- Laboratory for Conservation and Utilization of Bio-resource, Yunnan University, Kunming 650091, China
| | - Jingfei Huang
- State Key Laboratory of Genetic Resources and Evolution, Kunming Institute of Zoology, Chinese Academy of Sciences, Kunming 650223, China
| | - Dongdong Wu
- State Key Laboratory of Genetic Resources and Evolution, Kunming Institute of Zoology, Chinese Academy of Sciences, Kunming 650223, China.
| | - Yaping Zhang
- Laboratory for Conservation and Utilization of Bio-resource, Yunnan University, Kunming 650091, China; State Key Laboratory of Genetic Resources and Evolution, Kunming Institute of Zoology, Chinese Academy of Sciences, Kunming 650223, China.
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18
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Abstract
The rodent arenavirus glycoprotein complex encodes a stable signal peptide (SSP) that is an essential structural component of mature virions. The SSP, GP1, and GP2 subunits of the trimeric glycoprotein complex noncovalently interact to stud the surface of virions and initiate arenavirus infectivity. Nascent glycoprotein production undergoes two proteolytic cleavage events: first within the endoplasmic reticulum (ER) to cleave SSP from the remaining precursor GP1/2 (glycoprotein complex [GPC]) glycoprotein and second within the Golgi stacks by the cellular SKI-1/S1P for GP1/2 processing to yield GP1 and GP2 subunits. Cleaved SSP is not degraded but retained as an essential glycoprotein subunit. Here, we defined functions of the 58-amino-acid lymphocytic choriomeningitis virus (LCMV) SSP in regard to glycoprotein complex processing and maturation. Using molecular biology techniques, confocal microscopy, and flow cytometry, we detected SSP at the plasma membrane of transfected cells. Further, we identified a sorting signal (FLLL) near the carboxyl terminus of SSP that is required for glycoprotein maturation and trafficking. In the absence of SSP, the glycoprotein accumulated within the ER and was unable to undergo processing by SKI-1/S1P. Mutation of this highly conserved FLLL motif showed impaired glycoprotein processing and secretory pathway trafficking, as well as defective surface expression and pH-dependent membrane fusion. Immunoprecipitation of SSP confirmed an interaction between the signal peptide and the GP2 subunit; however, mutations within this FLLL motif disrupted the association of the GP1 subunit with the remaining glycoprotein complex. Several members of the Arenaviridae family are neglected human pathogens capable of causing illness ranging from a nondescript flu-like syndrome to fulminant hemorrhagic fever. Infections by arenaviruses are mediated by attachment of the virus glycoprotein to receptors on host cells and virion internalization by fusion within an acidified endosome. SSP plays a critical role in the fusion of the virus with the host cell membrane. Within infected cells, the retained glycoprotein SSP plays a neglected yet essential role in glycoprotein biosynthesis. Without this 6-kDa polypeptide, the glycoprotein precursor is retained within the endoplasmic reticulum, and trafficking to the plasma membrane where SSP, GP1, and GP2 localize for glycoprotein assembly into infectious virions is inhibited. To investigate SSP contributions to glycoprotein maturation and function, we created an SSP-tagged glycoprotein to directly detect and manipulate this subunit. This resource will aid future studies to identify host factors that mediate glycoprotein maturation.
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Conti BJ, Elferich J, Yang Z, Shinde U, Skach WR. Cotranslational folding inhibits translocation from within the ribosome-Sec61 translocon complex. Nat Struct Mol Biol 2014; 21:228-35. [PMID: 24561504 PMCID: PMC4351553 DOI: 10.1038/nsmb.2779] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2013] [Accepted: 01/27/2014] [Indexed: 12/31/2022]
Abstract
Eukaryotic secretory proteins cross the endoplasmic reticulum (ER) membrane through a protein-conducting channel contained within the ribosome-Sec61translocon complex (RTC). Using a zinc-finger sequence as a folding switch, we show that cotranslational folding of a secretory passenger inhibits translocation in canine ER microsomes and in human cells. Folding occurs within a cytosolically inaccessible environment, after ER targeting but before initiation of translocation, and it is most effective when the folded domain is 15-54 residues beyond the signal sequence. Under these conditions, substrate is diverted into cytosol at the stage of synthesis in which unfolded substrate enters the ER lumen. Moreover, the translocation block is reversed by passenger unfolding even after cytosol emergence. These studies identify an enclosed compartment within the assembled RTC that allows a short span of nascent chain to reversibly abort translocation in a substrate-specific manner.
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Affiliation(s)
- Brian J Conti
- Department of Biochemistry and Molecular Biology, Oregon Health and Sciences University, Portland, Oregon, USA
| | - Johannes Elferich
- Department of Biochemistry and Molecular Biology, Oregon Health and Sciences University, Portland, Oregon, USA
| | - Zhongying Yang
- Department of Biochemistry and Molecular Biology, Oregon Health and Sciences University, Portland, Oregon, USA
| | - Ujwal Shinde
- Department of Biochemistry and Molecular Biology, Oregon Health and Sciences University, Portland, Oregon, USA
| | - William R Skach
- Department of Biochemistry and Molecular Biology, Oregon Health and Sciences University, Portland, Oregon, USA
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20
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Pimenta J, Viegas A, Sardinha J, Martins IC, Cabrita EJ, Fontes CMGA, Prates JA, Pereira RMLN. NMR solution structure and SRP54M predicted interaction of the N-terminal sequence (1-30) of the ovine Doppel protein. Peptides 2013; 49:32-40. [PMID: 23973967 DOI: 10.1016/j.peptides.2013.08.013] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/18/2013] [Revised: 08/12/2013] [Accepted: 08/13/2013] [Indexed: 01/29/2023]
Abstract
Prion protein (PrP(C)) biosynthesis involves a multi-step process that includes translation and post-translational modifications. While PrP has been widely investigated, for the homolog Doppel (Dpl), limited knowledge is available. In this study, we focused on a vital step of eukaryotic protein biosynthesis: targeting by the signal recognition particle (SRP). Taking the ovine Dpl (OvDpl(1-30)) peptide as a template, we studied its behavior in two different hydrophobic environments using CD and NMR spectroscopy. In both trifluoroethanol (TFE) and dihexanoyl-sn-glycero-3-phosphatidylcholine (DHPC), the OvDpl(1-30) peptide revealed to fold in an alpha-helical conformation with a well-defined central region extending from residue Cys8 until Ser22. The NMR structure was subsequently included in a computational docking complex with the conserved M-domain of SRP54 protein (SRP54M), and further compared with the N-terminal structures of mouse Dpl and bovine PrP(C) proteins. This allowed the determination of (i) common predicted N-terminal/SRP54M polar contacts (Asp331, Gln335, Glu365 and Lys432) and (ii) different N-C orientations between prion and Dpl peptides at the SRP54M hydrophobic groove, that are in agreement with each peptide electrostatic potential. Together, these findings provide new insights into the biosynthesis of prion-like proteins. Besides they also show the role of protein conformational switches in signalization toward the endoplasmic membrane, a key event of major significance in the cell cycle. They are thus of general applicability to the study of the biological function of prion-like as well as other proteins.
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Affiliation(s)
- Jorge Pimenta
- Unidade de Biotecnologia e Recursos Genéticos, Instituto Nacional de Investigação Agrária e Veterinária, Quinta da Fonte Boa, Vale de Santarém, Portugal; CIISA, Faculdade de Medicina Veterinária (FMV), Universidade Técnica de Lisboa, Lisbon, Portugal
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21
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Tipper D, Martinez-Vilchez I, Markgren L, Kagalwala DZ. Mammalian Prion protein expression in yeast; a model for transmembrane insertion. Prion 2013; 7:477-87. [PMID: 24141197 DOI: 10.4161/pri.26850] [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: 01/08/2023] Open
Abstract
The prion protein (PrP), a GPI-anchored glycoprotein, is inefficiently secreted by mammalian microsomes, 50% being found as transmembrane (TM) proteins with the central TM1 segment spanning the membrane. TM1 hydrophobicity is marginal for lateral membrane insertion, which is primarily driven by hydrophobic interaction between the ER translocon and substrates in transit. Most inserted TM1 has its N-terminus in the ER lumen (Ntm orientation), as expected for arrest of normal secretion. However, 20% is found in inverted Ctm orientation. These are minor species in vivo, presumably a consequence of efficient quality control. PrP mutations that increase TM1 hydrophobicity result in increased Ctm insertion, both in vitro and in mouse brain, and a strong correlation is found between CtmPrP insertion and neuropathology in transgenic mice; a copper-dependent pathogenicity mechanism is suggested. PrP fusions with a C-terminal epitope tag, when expressed in yeast cells at moderate levels, appear to interact efficiently with the translocon, providing a useful model for testing the effects of PrP mutations on TM insertion and orientation. However, secretion of PrP by the mammalian translocon requires the TRAP complex, absent in yeast, where essentially all PrP ends up as TM species, 85-90% Ntm and 10-15% Ctm. Although yeast is, therefore, an incomplete mimic of mammalian PrP trafficking, effects on Ctm insertion of mutations increasing TM1 hydrophobicity closely reflect those seen in vitro. Electrostatic substrate-translocon interactions are a major determinant of TM protein insertion orientation and the yeast model was used to investigate the role of the large negative charge difference across TM1, a likely cause of translocation delay that would favor TM insertion and Ctm orientation. An increase in ΔCh from -5 to -7 caused a marked increase in Ctm insertion, while a decrease to -3 or -1 allowed 35 and about 65% secretion, respectively. Utility of the yeast model and the role of this charge difference in driving PrP membrane insertion are confirmed.
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Affiliation(s)
- Donald Tipper
- Microbiology and Physiological Systems Department; University of Massachusetts Medical School; Worcester MA USA
| | | | - Lucas Markgren
- Mathematics Department; Doherty Memorial High School; Worcester MA USA
| | - Din Z Kagalwala
- Department of Anesthesiology; Hackensack University Medical Center; Hackensack, NJ USA
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22
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Conserved roles of the prion protein domains on subcellular localization and cell-cell adhesion. PLoS One 2013; 8:e70327. [PMID: 23936187 PMCID: PMC3729945 DOI: 10.1371/journal.pone.0070327] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2013] [Accepted: 06/17/2013] [Indexed: 11/18/2022] Open
Abstract
Analyses of cultured cells and transgenic mice expressing prion protein (PrP) deletion mutants have revealed that some properties of PrP -such as its ability to misfold, aggregate and trigger neurotoxicity- are controlled by discrete molecular determinants within its protein domains. Although the contributions of these determinants to PrP biosynthesis and turnover are relatively well characterized, it is still unclear how they modulate cellular functions of PrP. To address this question, we used two defined activities of PrP as functional readouts: 1) the recruitment of PrP to cell-cell contacts in Drosophila S2 and human MCF-7 epithelial cells, and 2) the induction of PrP embryonic loss- and gain-of-function phenotypes in zebrafish. Our results show that homologous mutations in mouse and zebrafish PrPs similarly affect their subcellular localization patterns as well as their in vitro and in vivo activities. Among PrP’s essential features, the N-terminal leader peptide was sufficient to drive targeting of our constructs to cell contact sites, whereas lack of GPI-anchoring and N-glycosylation rendered them inactive by blocking their cell surface expression. Importantly, our data suggest that the ability of PrP to homophilically trans-interact and elicit intracellular signaling is primarily encoded in its globular domain, and modulated by its repetitive domain. Thus, while the latter induces the local accumulation of PrPs at discrete punctae along cell contacts, the former counteracts this effect by promoting the continuous distribution of PrP. In early zebrafish embryos, deletion of either domain significantly impaired PrP’s ability to modulate E-cadherin cell adhesion. Altogether, these experiments relate structural features of PrP to its subcellular distribution and in vivo activity. Furthermore, they show that despite their large evolutionary history, the roles of PrP domains and posttranslational modifications are conserved between mouse and zebrafish.
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23
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Tian C, Dong X. The structure of prion: is it enough for interpreting the diverse phenotypes of prion diseases? Acta Biochim Biophys Sin (Shanghai) 2013; 45:429-34. [PMID: 23459557 DOI: 10.1093/abbs/gmt021] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Prion diseases, or transmissible spongiform encephalopathies, are neurodegenerative diseases, which affect human and many species of animals with 100% fatality rate. The most accepted etiology for prion disease is 'prion', which arises from the conversion from cellular PrP(C) to the pathological PrP(Sc). This review discussed the characteristic structure of PrP, including PRNP gene, PrP(C), PrP(Sc), PrP amyloid, and prion strains.
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Affiliation(s)
- Chan Tian
- State Key Laboratory for Infectious Disease Prevention and Control, National Institute for Viral Disease Control and Prevention, Chinese Center for Disease Control and Prevention, Beijing 102206, China
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Kim J, Choi I, Park JY, Kang SW. Specific inhibition of hamster prion protein translocation by the dodecadepsipeptide valinomycin. Exp Cell Res 2013; 319:2049-2057. [PMID: 23623970 DOI: 10.1016/j.yexcr.2013.04.012] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2013] [Revised: 04/04/2013] [Accepted: 04/16/2013] [Indexed: 12/23/2022]
Abstract
Regulating the entry of secretory and membrane proteins into the ER is shown to be an important physiological process, in terms of controlling quantity, localization and therefore function of target proteins. However, few small molecule modulators are available to pharmacologically regulate translocation of a specific protein. Here, we identified a small molecule that specifically inhibits pathogenic PrP biosynthesis using a highly sensitive and reproducible assay based on the fluorogenic substrate reporter PrP. This molecule specifically destabilized the signal peptide of PrP, leading to cotranslational rerouting of a significant amount of nascent PrP to proteasome-dependent degradation pathway in the cytosol. This study suggests that regulating differential translocation efficiency attributable to sequence diversity in signal peptides of disease-causing secretory and membrane proteins using cell-permeable small molecules may be a potential therapeutic approach for diseases associated with impaired protein biogenesis.
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Affiliation(s)
- Jiyeon Kim
- Department of Biomedical Sciences, University of Ulsan College of Medicine, 88, Olympic-ro 43-gil, Songpa-gu, Seoul 138-736, Republic of Korea
| | - Ilho Choi
- Department of Biomedical Sciences, University of Ulsan College of Medicine, 88, Olympic-ro 43-gil, Songpa-gu, Seoul 138-736, Republic of Korea
| | - Joong-Yeol Park
- Department of Internal Medicine, Asan Medical Center, University of Ulsan College of Medicine, Seoul, Republic of Korea
| | - Sang-Wook Kang
- Department of Biomedical Sciences, University of Ulsan College of Medicine, 88, Olympic-ro 43-gil, Songpa-gu, Seoul 138-736, Republic of Korea; Department of Anatomy and Cell Biology, University of Ulsan College of Medicine, Seoul, Republic of Korea; Cell Dysfunction Research Center, University of Ulsan College of Medicine, Seoul, Republic of Korea.
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Nieznanska H, Dudek E, Zajkowski T, Szczesna E, Kasprzak AA, Nieznanski K. Prion protein impairs kinesin-driven transport. Biochem Biophys Res Commun 2012; 425:788-93. [PMID: 22885185 DOI: 10.1016/j.bbrc.2012.07.153] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2012] [Accepted: 07/27/2012] [Indexed: 01/11/2023]
Abstract
Our previous studies have demonstrated that prion protein (PrP) leads to disassembly of microtubular cytoskeleton through binding to tubulin and its oligomerization. Here we found that PrP-treated cells exhibited improper morphology of mitotic spindles. Formation of aberrant spindles may result not only from altered microtubule dynamics - as expected from PrP-induced tubulin oligomerization - but also from impairing the function of molecular motors. Therefore we checked whether binding of PrP to microtubules affected movement generated by Ncd - a kinesin responsible for the proper organization of division spindles. We found that PrP inhibited Ncd-driven transport of microtubules. Most probably, the inhibition of the microtubule movement resulted from PrP-induced changes in the microtubule structure since Ncd-microtubule binding was reduced already at low PrP to tubulin molar ratios. This study suggests another plausible mechanism of PrP cytotoxicity related to the interaction with tubulin, namely impeding microtubule-dependent transport.
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Affiliation(s)
- Hanna Nieznanska
- Department of Biochemistry, Nencki Institute of Experimental Biology, 3 Pasteur St., 02-093 Warsaw, Poland
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26
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Human prion protein binds Argonaute and promotes accumulation of microRNA effector complexes. Nat Struct Mol Biol 2012; 19:517-24, S1. [PMID: 22484317 DOI: 10.1038/nsmb.2273] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2011] [Accepted: 02/28/2012] [Indexed: 12/13/2022]
Abstract
Despite intense research in the context of neurodegenerative diseases associated with its misfolding, the endogenous human prion protein PrP(C) (or PRNP) has poorly understood physiological functions. Whereas most PrP(C) is exposed to the extracellular environment, conserved domains result in transmembrane forms of PrP(C) that traffic in the endolysosomal system and are linked to inherited and infectious neuropathologies. One transmembrane PrP(C) variant orients the N-terminal 'octarepeat' domain into the cytoplasm. Here we demonstrate that the octarepeat domain of human PrP(C) contains GW/WG motifs that bind Argonaute (AGO) proteins, the essential components of microRNA (miRNA)-induced silencing complexes (miRISCs). Transmembrane PrP(C) preferentially binds AGO, and PrP(C) promotes formation or stability of miRISC effector complexes containing the trinucleotide repeat-containing gene 6 proteins (TNRC6) and miRNA-repressed mRNA. Accordingly, effective repression of several miRNA targets requires PrP(C). We propose that dynamic interactions between PrP(C)-enriched endosomes and subcellular foci of AGO underpin these effects.
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Genetic variability of the coding region for the prion protein gene (PRNP) in gayal (Bos frontalis). Mol Biol Rep 2011; 39:2011-20. [PMID: 21633886 DOI: 10.1007/s11033-011-0948-2] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2011] [Accepted: 05/26/2011] [Indexed: 10/18/2022]
Abstract
The gayal (Bos frontalis) is a rare semi-wild bovid species in which bovine spongiform encephalopathy (BSE) has not been reported. Polymorphisms of the prion protein gene (PRNP) have been correlated significantly with resistance to BSE. In this study, the coding region of PRNP was cloned and characterized in samples from 125 gayal. A total of ten single nucleotide polymorphisms (SNPs), including six silent mutations (C60T, G75A, A108T, G126A, C357T and C678T) and four mis-sense mutations (C8A, G145A, G461A and C756G), corresponding to amino acids T3K, G49S9, N154S and I252M were identified, revealing high genetic diversity. Three novel SNPs including C60T, G145A and C756G, which have not been reported previously in bovid species, were retrieved. There also was one insertion-deletion (187Del24) at the N-terminal octapeptide repeat region. Alignment of nucleotide and amino acid sequences showed a high degree of similarity with other bovid species. Using phylogenetic analyses it was revealed that gayal has a close genetic relationship with Zebu cattle. In short, preliminary information is provided about genotypes of the PRNP in gayal. This could assist with the study of the pathogenesis of transmissible spongiform encephalopathies and cross species transmission as well as a molecular breeding project for gayal in China.
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Chen Q, Jagannathan S, Reid DW, Zheng T, Nicchitta CV. Hierarchical regulation of mRNA partitioning between the cytoplasm and the endoplasmic reticulum of mammalian cells. Mol Biol Cell 2011; 22:2646-58. [PMID: 21613539 PMCID: PMC3135488 DOI: 10.1091/mbc.e11-03-0239] [Citation(s) in RCA: 61] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023] Open
Abstract
This study reveals that mRNAs are partitioned between the cytosol and endoplasmic reticulum (ER) compartments in a hierarchical manner and identifies a prominent role for the ER in global protein synthesis. Two modes of mRNA association with the ER are defined: ribosome dependent and ribosome independent. The mRNA transcriptome is currently thought to be partitioned between the cytosol and endoplasmic reticulum (ER) compartments by binary selection; mRNAs encoding cytosolic/nucleoplasmic proteins are translated on free ribosomes, and mRNAs encoding topogenic signal-bearing proteins are translated on ER-bound ribosomes, with ER localization being conferred by the signal-recognition particle pathway. In subgenomic and genomic analyses of subcellular mRNA partitioning, we report an overlapping subcellular distribution of cytosolic/nucleoplasmic and topogenic signal-encoding mRNAs, with mRNAs of both cohorts displaying noncanonical subcellular partitioning patterns. Unexpectedly, the topogenic signal-encoding mRNA transcriptome was observed to partition in a hierarchical, cohort-specific manner. mRNAs encoding resident proteins of the endomembrane system were clustered at high ER-enrichment values, whereas mRNAs encoding secretory pathway cargo were broadly represented on free and ER-bound ribosomes. Two distinct modes of mRNA association with the ER were identified. mRNAs encoding endomembrane-resident proteins were bound via direct, ribosome-independent interactions, whereas mRNAs encoding secretory cargo displayed predominantly ribosome-dependent modes of ER association. These data indicate that mRNAs are partitioned between the cytosol and ER compartments via a hierarchical system of intrinsic and encoded topogenic signals and identify mRNA cohort-restricted modes of mRNA association with the ER.
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Affiliation(s)
- Qiang Chen
- Department of Cell Biology, Duke University Medical Center, Durham, NC 27710, USA
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29
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Abstract
Prion diseases in humans and animals are characterized by progressive neurodegeneration and the formation of infectious particles called prions. Both features are intimately linked to a conformational transition of the cellular prion protein (PrP(C)) into aberrantly folded conformers with neurotoxic and self-replicating activities. Interestingly, there is increasing evidence that the infectious and neurotoxic properties of PrP conformers are not necessarily coupled. Transgenic mouse models revealed that some PrP mutants interfere with neuronal function in the absence of infectious prions. Vice versa, propagation of prions can occur without causing neurotoxicity. Consequently, it appears plausible that two partially independent pathways exist, one pathway leading to the propagation of infectious prions and another one that mediates neurotoxic signaling. In this review we will summarize current knowledge of neurotoxic PrP conformers and discuss the role of PrP(C) as a mediator of both stress-protective and neurotoxic signaling cascades.
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30
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Silva JL, Vieira TCRG, Gomes MPB, Rangel LP, Scapin SMN, Cordeiro Y. Experimental approaches to the interaction of the prion protein with nucleic acids and glycosaminoglycans: Modulators of the pathogenic conversion. Methods 2010; 53:306-17. [PMID: 21145399 DOI: 10.1016/j.ymeth.2010.12.002] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2010] [Accepted: 12/02/2010] [Indexed: 11/17/2022] Open
Abstract
The concept that transmissible spongiform encephalopathies (TSEs) are caused only by proteins has changed the traditional paradigm that disease transmission is due solely to an agent that carries genetic information. The central hypothesis for prion diseases proposes that the conversion of a cellular prion protein (PrP(C)) into a misfolded, β-sheet-rich isoform (PrP(Sc)) accounts for the development of (TSE). There is substantial evidence that the infectious material consists chiefly of a protein, PrP(Sc), with no genomic coding material, unlike a virus particle, which has both. However, prions seem to have other partners that chaperone their activities in converting the PrP(C) into the disease-causing isoform. Nucleic acids (NAs) and glycosaminoglycans (GAGs) are the most probable accomplices of prion conversion. Here, we review the recent experimental approaches that have been employed to characterize the interaction of prion proteins with nucleic acids and glycosaminoglycans. A PrP recognizes many nucleic acids and GAGs with high affinities, and this seems to be related to a pathophysiological role for this interaction. A PrP binds nucleic acids and GAGs with structural selectivity, and some PrP:NA complexes can become proteinase K-resistant, undergoing amyloid oligomerization and conversion to a β-sheet-rich structure. These results are consistent with the hypothesis that endogenous polyanions (such as NAs and GAGs) may accelerate the rate of prion disease progression by acting as scaffolds or lattices that mediate the interaction between PrP(C) and PrP(Sc) molecules. In addition to a still-possible hypothesis that nucleic acids and GAGs, especially those from the host, may modulate the conversion, the recent structural characterization of the complexes has raised the possibility of developing new diagnostic and therapeutic strategies.
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Affiliation(s)
- Jerson L Silva
- Centro Nacional de Ressonância Magnética Nuclear Jiri Jonas, Instituto de Bioquímica Médica, Instituto Nacional de Ciência e Tecnologia de Biologia Estrutural e Bioimagem, Brazil.
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31
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Emerman AB, Zhang ZR, Chakrabarti O, Hegde RS. Compartment-restricted biotinylation reveals novel features of prion protein metabolism in vivo. Mol Biol Cell 2010; 21:4325-37. [PMID: 20980618 PMCID: PMC3002386 DOI: 10.1091/mbc.e10-09-0742] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022] Open
Abstract
Proteins are often made in more than one form, with alternate versions sometimes residing in different cellular compartments than the primary species. The mammalian prion protein (PrP), a cell surface GPI-anchored protein, is a particularly noteworthy example for which minor cytosolic and transmembrane forms have been implicated in disease pathogenesis. To study these minor species, we used a selective labeling strategy in which spatially restricted expression of a biotinylating enzyme was combined with asymmetric engineering of the cognate acceptor sequence into PrP. Using this method, we could show that even wild-type PrP generates small amounts of the (Ctm)PrP transmembrane form. Selective detection of (Ctm)PrP allowed us to reveal its N-terminal processing, long half-life, residence in both intracellular and cell surface locations, and eventual degradation in the lysosome. Surprisingly, some human disease-causing mutants in PrP selectively stabilized (Ctm)PrP, revealing a previously unanticipated mechanism of (Ctm)PrP up-regulation that may contribute to disease. Thus, spatiotemporal tagging has uncovered novel aspects of normal and mutant PrP metabolism and should be readily applicable to the analysis of minor topologic isoforms of other proteins.
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Affiliation(s)
- Amy B Emerman
- Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD 20892, USA
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32
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Domingo B, Gasset M, Durán-Prado M, Castaño JP, Serrano A, Fischer T, Llopis J. Discrimination between alternate membrane protein topologies in living cells using GFP/YFP tagging and pH exchange. Cell Mol Life Sci 2010; 67:3345-54. [PMID: 20454916 PMCID: PMC11115537 DOI: 10.1007/s00018-010-0386-7] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2010] [Revised: 03/30/2010] [Accepted: 04/22/2010] [Indexed: 02/05/2023]
Abstract
Membrane protein function is determined by the relative organization of the protein domains with respect to the membrane. We have experimentally verified the topology of a protein with diverse orientations arising from a single primary sequence (the cellular prion protein, PrP(C)), a novel somatostatin truncated receptor, and the Golgi-associated protein GPBP(91). Tagging with fluorescent proteins (FP) allows location of their expression at the plasma membrane or at endomembranes, but does not inform about their orientation. Exploiting the pH dependency of some FPs, we developed a pH exchange assay in which extracellularly exposed FPs are quenched by application of low pH buffer. We constructed standards to demonstrate and calibrate the assay, and the method was adapted for acidic organelle membrane proteins. This method can serve as a proof of concept, experimentally confirming and/or discriminating in living cells among theoretical topology predictions, providing the proportion of inside/outside orientation for proteins with multiple forms.
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Affiliation(s)
- Beatriz Domingo
- Centro Regional de Investigaciones Biomédicas y Facultad de Medicina, Universidad de Castilla-La Mancha, 02006 Albacete, Spain
| | - María Gasset
- Instituto de Química-Física Rocasolano, CSIC, Serrano 119, 28006 Madrid, Spain
| | - Mario Durán-Prado
- Instituto de Parasitología y Biomedicina López-Neyra, CSIC, 18100 Granada, Spain
| | - Justo P. Castaño
- Departamento de Biología Celular, Fisiología e Inmunología, Universidad de Córdoba, Edificio Severo Ochoa, Planta 3. Campus de Rabanales, Córdoba, Spain
- Instituto Maimónides de Investigación Biomédica de Córdoba (IMIBIC), Córdoba, Spain
- CIBER Fisiopatología de la Obesidad y Nutrición (CIBERobn 06/03), Córdoba, Spain
| | | | | | - Juan Llopis
- Centro Regional de Investigaciones Biomédicas y Facultad de Medicina, Universidad de Castilla-La Mancha, 02006 Albacete, Spain
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33
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Zhao H, Wang XY, Zou W, Zhang YP. Prion protein gene (PRNP) polymorphisms in native Chinese cattle. Genome 2010; 53:138-45. [PMID: 20140032 DOI: 10.1139/g09-087] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Polymorphisms in four regions of the bovine prion protein gene (PRNP) confer susceptibility to bovine spongiform encephalopathy (BSE). These polymorphisms include a 23-bp insertion/deletion (indel) in the promoter region, a 12-bp indel in intron 1, an octapeptide repeat or 24-bp indel in the open reading frame, and a single nucleotide polymorphism (SNP) in the coding region. In this study, we investigated the frequency distributions of genotypes, alleles, and haplotypes at these indel sites in 349 native Chinese cattle and sequence variants in 50 samples. Our results showed that cattle in southern China have low frequencies of the 12-bp deletion allele and the 23-bp deletion / 12-bp deletion haplotype, which have been suggested to be relevant to BSE susceptibility. Interestingly, a significant difference was observed between BSE-affected cattle and healthy Chinese cattle in the 12-bp indel polymorphism. A total of 14 SNPs were discovered in the coding region of PRNP in Chinese cattle. Three of these SNPs were associated with amino acid changes (K3T, P54S, and S154N). The E211K substitution that was recently reported in the US atypical BSE case was not detected in this study.
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Affiliation(s)
- Hui Zhao
- Laboratory for Conservation and Utilization of Bioresource, Yunnan University, Kunming, China
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34
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Zou WQ, Langeveld J, Xiao X, Chen S, McGeer PL, Yuan J, Payne MC, Kang HE, McGeehan J, Sy MS, Greenspan NS, Kaplan D, Wang GX, Parchi P, Hoover E, Kneale G, Telling G, Surewicz WK, Kong Q, Guo JP. PrP conformational transitions alter species preference of a PrP-specific antibody. J Biol Chem 2010; 285:13874-84. [PMID: 20194495 DOI: 10.1074/jbc.m109.088831] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The epitope of the 3F4 antibody most commonly used in human prion disease diagnosis is believed to consist of residues Met-Lys-His-Met (MKHM) corresponding to human PrP-(109-112). This assumption is based mainly on the observation that 3F4 reacts with human and hamster PrP but not with PrP from mouse, sheep, and cervids, in which Met at residue 112 is replaced by Val. Here we report that, by brain histoblotting, 3F4 did not react with PrP of uninfected transgenic mice expressing elk PrP; however, it did show distinct immunoreactivity in transgenic mice infected with chronic wasting disease. Compared with human PrP, the 3F4 reactivity with the recombinant elk PrP was 2 orders of magnitude weaker, as indicated by both Western blotting and surface plasmon resonance. To investigate the molecular basis of these species- and conformer-dependent preferences of 3F4, the epitope was probed by peptide membrane array and antigen competition experiments. Remarkably, the 3F4 antibody did not react with MKHM but reacted strongly with KTNMK (corresponding to human PrP-(106-110)), a sequence that is also present in cervids, sheep, and cattle. 3F4 also reacted with elk PrP peptides containing KTNMKHV. We concluded that the minimal sequence for the 3F4 epitope consists of residues KTNMK, and the species- and conformer-dependent preferences of 3F4 arise largely from the interactions between Met(112) (human PrP) or Val(115) (cervid PrP) and adjacent residues.
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Affiliation(s)
- Wen-Quan Zou
- Department of Pathology, Case Western Reserve University School of Medicine, Cleveland, Ohio 4410, USA.
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35
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Rane NS, Chakrabarti O, Feigenbaum L, Hegde RS. Signal sequence insufficiency contributes to neurodegeneration caused by transmembrane prion protein. ACTA ACUST UNITED AC 2010; 188:515-26. [PMID: 20156965 PMCID: PMC2828915 DOI: 10.1083/jcb.200911115] [Citation(s) in RCA: 62] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Improving the efficiency of PrP translocation into the ER decreases levels of transmembrane bound protein and rescues mice from prion disease. Protein translocation into the endoplasmic reticulum is mediated by signal sequences that vary widely in primary structure. In vitro studies suggest that such signal sequence variations may correspond to subtly different functional properties. Whether comparable functional differences exist in vivo and are of sufficient magnitude to impact organism physiology is unknown. Here, we investigate this issue by analyzing in transgenic mice the impact of signal sequence efficiency for mammalian prion protein (PrP). We find that replacement of the average efficiency signal sequence of PrP with more efficient signals rescues mice from neurodegeneration caused by otherwise pathogenic PrP mutants in a downstream hydrophobic domain (HD). This effect is explained by the demonstration that efficient signal sequence function precludes generation of a cytosolically exposed, disease-causing transmembrane form of PrP mediated by the HD mutants. Thus, signal sequences are functionally nonequivalent in vivo, with intrinsic inefficiency of the native PrP signal being required for pathogenesis of a subset of disease-causing PrP mutations.
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Affiliation(s)
- Neena S Rane
- Cell Biology and Metabolism Program, National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD 20892, USA
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36
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Nieznanski K. Interactions of prion protein with intracellular proteins: so many partners and no consequences? Cell Mol Neurobiol 2009; 30:653-66. [PMID: 20041289 DOI: 10.1007/s10571-009-9491-2] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2009] [Accepted: 12/18/2009] [Indexed: 10/20/2022]
Abstract
Prion protein (PrP) plays a key role in the pathogenesis of transmissible spongiform encephalopathies (TSEs)--fatal diseases of the central nervous system. Its physiological function as well as exact role in neurodegeneration remain unclear, hence screens for proteins interacting with PrP seem to be the most promising approach to elucidating these issues. PrP is mostly a plasma membrane-anchored extracellular glycoprotein and only a small fraction resides inside the cell, yet the number of identified intracellular partners of PrP is comparable to that of its membranal or extracellular interactors. Since some TSEs are accompanied by significantly increased levels of cytoplasmic PrP and this fraction of the protein has been found to be neurotoxic, it is of particular interest to characterize the intracellular interactome of PrP. It seems reasonable that at elevated cytoplasmic levels, PrP may exert cytotoxic effect by affecting the physiological functions of its intracellular interactors. This review is focused on the cytoplasmic partners of PrP along with possible consequences of their binding.
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Affiliation(s)
- Krzysztof Nieznanski
- Department of Biochemistry, Polish Academy of Sciences, Nencki Institute of Experimental Biology, 3 Pasteur St, Warsaw 02093, Poland.
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37
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Osiecka KM, Nieznanska H, Skowronek KJ, Karolczak J, Schneider G, Nieznanski K. Prion protein region 23-32 interacts with tubulin and inhibits microtubule assembly. Proteins 2009; 77:279-96. [PMID: 19422054 DOI: 10.1002/prot.22435] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
In previous studies we have demonstrated that prion protein (PrP) binds directly to tubulin and this interaction leads to the inhibition of microtubule formation by inducement of tubulin oligomerization. This report is aimed at mapping the regions of PrP and tubulin involved in the interaction and identification of PrP domains responsible for tubulin oligomerization. Preliminary studies focused our attention to the N-terminal flexible part of PrP encompassing residues 23-110. Using a panel of deletion mutants of PrP, we identified two microtubule-binding motifs at both ends of this part of the molecule. We found that residues 23-32 constitute a major site of interaction, whereas residues 101-110 represent a weak binding site. The crucial role of the 23-32 sequence in the interaction with tubulin was confirmed employing chymotryptic fragments of PrP. Surprisingly, the octarepeat region linking the above motifs plays only a supporting role in the interaction. The binding of Cu(2+) to PrP did not affect the interaction. We also demonstrate that PrP deletion mutants lacking residues 23-32 exhibit very low efficiency in the inducement of tubulin oligomerization. Moreover, a synthetic peptide corresponding to this sequence, but not that identical with fragment 101-110, mimics the effects of the full-length protein on tubulin oligomerization and microtubule assembly. At the cellular level, peptide composed of the PrP motive 23-30 and signal sequence (1-22) disrupted the microtubular cytoskeleton. Using tryptic and chymotryptic fragments of alpha- and beta-tubulin, we mapped the docking sites for PrP within the C-terminal domains constituting the outer surface of microtubule.
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Affiliation(s)
- Katarzyna M Osiecka
- Department of Biochemistry, Nencki Institute of Experimental Biology, Warsaw, Poland
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38
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Hiss JA, Schneider G. Architecture, function and prediction of long signal peptides. Brief Bioinform 2009; 10:569-78. [DOI: 10.1093/bib/bbp030] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
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39
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Chakrabarti O, Ashok A, Hegde RS. Prion protein biosynthesis and its emerging role in neurodegeneration. Trends Biochem Sci 2009; 34:287-95. [PMID: 19447626 DOI: 10.1016/j.tibs.2009.03.001] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2009] [Revised: 02/23/2009] [Accepted: 03/02/2009] [Indexed: 01/03/2023]
Abstract
Various fatal neurodegenerative disorders are caused by altered metabolism of the prion protein (PrP). These diseases are typically transmissible by an unusual 'protein-only' mechanism in which a misfolded isomer, PrP(Sc), confers its aberrant conformation onto normal cellular PrP. An impressive range of studies has investigated nearly every aspect of this fascinating event; yet, our understanding of how PrP(Sc) accumulation might lead to cellular dysfunction and neurodegeneration is trifling. Recent advances in our understanding of normal PrP biosynthesis and degradation might have unexpectedly shed new light on this complex problem. Indeed, our current understanding of normal PrP cell biology, coupled with a growing appreciation of its complex metabolism, is providing new hypotheses for PrP-mediated neurodegeneration.
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Affiliation(s)
- Oishee Chakrabarti
- Cell Biology and Metabolism Program, National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD 20892, USA
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40
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The Nrf1 CNC/bZIP protein is a nuclear envelope-bound transcription factor that is activated by t-butyl hydroquinone but not by endoplasmic reticulum stressors. Biochem J 2009; 418:293-310. [PMID: 18990090 DOI: 10.1042/bj20081575] [Citation(s) in RCA: 62] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
In rat liver RL-34 cells, endogenous Nrf1 (nuclear factor-erythroid 2 p45 subunit-related factor 1) is localized in the ER (endoplasmic reticulum) where it exists as a glycosylated protein. Electron microscopy has demonstrated that ectopic Nrf1 in COS-1 cells is located in the ER and the NE (nuclear envelope). Subcellular fractionation, together with a membrane proteinase protection assay, revealed that Nrf1 is an integral membrane protein with both luminal and cytoplasmic domains. The N-terminal 65 residues of Nrf1 direct its integration into the ER and NE membranes and tether it to a Triton X-100-resistant membrane microdomain that is associated with lipid rafts. The activity of Nrf1 was increased by the electrophile tBHQ (t-butyl hydroquinone) probably through an N-terminal domain-dependent process. We found that the NST (Asn/Ser/Thr-rich) domain, along with AD1 (acidic domain 1), contributes positively to the transactivation activity of full-length Nrf1. Furthermore, the NST domain contains seven putative -Asn-Xaa-Ser/Thr- glycosylation sites and, when glycosylation was prevented by replacing all of the seven asparagine residues with either glutamine (Nrf1(1-7xN/Q)) or aspartic acid (Nrf1(1-7xN/D)), the former multiple point mutant possessed less activity than the wild-type factor, whereas the latter mutant exhibited substantially greater activity. Lastly, the ER stressors tunicamycin, thapsigargin and Brefeldin A were found to inhibit basal Nrf1 activity by approximately 25%, and almost completely prevented induction of Nrf1-mediated transactivation by tBHQ. Collectively, these results suggest that the activity of Nrf1 critically depends on its topology within the ER, and that this is modulated by redox stressors, as well as by its glycosylation status.
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Alken M, Schmidt A, Rutz C, Furkert J, Kleinau G, Rosenthal W, Schülein R. The sequence after the signal peptide of the G protein-coupled endothelin B receptor is required for efficient translocon gating at the endoplasmic reticulum membrane. Mol Pharmacol 2009; 75:801-11. [PMID: 19136571 DOI: 10.1124/mol.108.051581] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023] Open
Abstract
The heptahelical G protein-coupled receptors (GPCRs) must reach their correct subcellular location to exert their function. Receptor domains relevant for receptor trafficking include signal sequences mediating receptor integration into the membrane of the endoplasmic reticulum (ER) and anterograde or retrograde transport signals promoting receptor sorting into the vesicles of the secretory pathway. In addition, receptors must be correctly folded to pass the quality control system of the early secretory pathway. Taking the endothelin B receptor as a model, we describe a new type of a transport-relevant GPCR domain. Deletion of this domain (residues Glu(28) to Trp(54)) leads to a fully functional receptor protein that is expressed at a lower level than the wild-type receptor. Subcellular localization experiments and glycosylation state analyses demonstrate that the mutant receptor is neither misfolded, retained intracellularly, nor misrouted. Fluorescence recovery after photobleaching analyses demonstrate that constitutive internalization is also not affected. By using an in vitro prion protein targeting assay, we show that this domain is necessary for efficient translocon gating at the ER membrane during early receptor biogenesis. Taken together, we identified a novel transport-relevant domain in the GPCR protein family. Our data may also be relevant for other GPCRs and unrelated integral membrane proteins.
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Affiliation(s)
- Martina Alken
- Leibniz-Institut für Molekulare Pharmakologie, Berlin, Germany
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Rane NS, Kang SW, Chakrabarti O, Feigenbaum L, Hegde RS. Reduced translocation of nascent prion protein during ER stress contributes to neurodegeneration. Dev Cell 2008; 15:359-370. [PMID: 18804434 DOI: 10.1016/j.devcel.2008.06.015] [Citation(s) in RCA: 105] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2007] [Revised: 05/09/2008] [Accepted: 06/26/2008] [Indexed: 10/21/2022]
Abstract
During acute stress in the endoplasmic reticulum (ER), mammalian prion protein (PrP) is temporarily prevented from translocation into the ER and instead routed directly for cytosolic degradation. This "pre-emptive" quality control (pQC) system benefits cells by minimizing PrP aggregation in the secretory pathway during ER stress. However, the potential toxicity of cytosolic PrP raised the possibility that persistent pQC of PrP contributes to neurodegeneration in prion diseases. Here, we find evidence of ER stress and decreased translocation of nascent PrP during prion infection. Transgenic mice expressing a PrP variant with reduced translocation at levels expected during ER stress was sufficient to cause several mild age-dependent clinical and histological manifestations of PrP-mediated neurodegeneration. Thus, an ordinarily adaptive quality-control pathway can be contextually detrimental over long time periods. We propose that one mechanism of prion-mediated neurodegeneration involves an indirect ER stress-dependent effect on nascent PrP biosynthesis and metabolism.
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Affiliation(s)
- Neena S Rane
- Cell Biology and Metabolism Program, National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD, 20892, USA
| | - Sang-Wook Kang
- Cell Biology and Metabolism Program, National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD, 20892, USA
| | - Oishee Chakrabarti
- Cell Biology and Metabolism Program, National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD, 20892, USA
| | - Lionel Feigenbaum
- Laboratory of Animal Sciences, National Cancer Institute, Frederick, MD 21702, USA
| | - Ramanujan S Hegde
- Cell Biology and Metabolism Program, National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD, 20892, USA.
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Lin DTS, Jodoin J, Baril M, Goodyer CG, Leblanc AC. Cytosolic prion protein is the predominant anti-Bax prion protein form: exclusion of transmembrane and secreted prion protein forms in the anti-Bax function. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2008; 1783:2001-12. [PMID: 18590778 DOI: 10.1016/j.bbamcr.2008.05.022] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/17/2008] [Revised: 05/06/2008] [Accepted: 05/27/2008] [Indexed: 01/01/2023]
Abstract
Prion protein (PrP) prevents Bax-mediated cell death by inhibiting the initial Bax conformational change that converts cytosolic Bax into a pro-apoptotic protein. PrP is mostly a glycophosphatidylinositol-anchored cell surface protein but it is also retrotranslocated into cytosolic PrP (CyPrP) or can become a type 1 or type 2 transmembrane protein. To determine the form and subcellular location of the PrP that has anti-Bax function, we co-expressed various Syrian hamster PrP (SHaPrP) mutants that favour specific PrP topologies and subcellular localization with N-terminally green fluorescent protein tagged pro-apoptotic Bax (EGFP-Bax) in MCF-7 cells and primary human neurons. Mutants that generate both CyPrP and secreted PrP ((Sec)PrP) or only CyPrP have anti-Bax activity. Mutants that produce (Ctm)PrP or (Ntm)PrP lose the anti-Bax activity, despite their ability to also make (Sec)PrP. Transmembrane-generating mutants do not produce CyPrP and both normal and cognate mutant forms of CyPrP rescue against the loss of anti-Bax activity. (Sec)PrP-generating constructs also produce non-membrane attached (Sec)PrP. However, this form of PrP has minimal anti-Bax activity. We conclude that CyPrP is the predominant form of PrP with anti-Bax function. These results imply that the retrotranslocation of PrP encompasses a survival function and is not merely a pathway for the proteasomal degradation of misfolded protein.
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Affiliation(s)
- David T S Lin
- Bloomfield Center for Research in Aging, LDI, Montréal, QC, Canada H3T 1E2
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Dong CF, Shi S, Wang XF, An R, Li P, Chen JM, Wang X, Wang GR, Shan B, Zhang BY, Han J, Dong XP. The N-terminus of PrP is responsible for interacting with tubulin and fCJD related PrP mutants possess stronger inhibitive effect on microtubule assembly in vitro. Arch Biochem Biophys 2008; 470:83-92. [DOI: 10.1016/j.abb.2007.11.007] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2007] [Revised: 11/08/2007] [Accepted: 11/11/2007] [Indexed: 10/22/2022]
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Relevance of the N-terminal NLS-like sequence of the prion protein for membrane perturbation effects. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2008; 1778:206-13. [DOI: 10.1016/j.bbamem.2007.09.034] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/23/2007] [Revised: 08/28/2007] [Accepted: 09/23/2007] [Indexed: 11/19/2022]
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46
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Harrison CF, Barnham KJ, Hill AF. Neurotoxic species in prion disease: a role for PrP isoforms? J Neurochem 2007; 103:1709-20. [DOI: 10.1111/j.1471-4159.2007.04936.x] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
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Han J, Zhang J, Yao H, Wang X, Li F, Chen L, Gao C, Gao J, Nie K, Zhou W, Dong X. Study on interaction between microtubule associated protein tau and prion protein. ACTA ACUST UNITED AC 2007; 49:473-9. [PMID: 17172055 DOI: 10.1007/s11427-006-2019-9] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
Abstract
Microtubule-associated protein tau is considered to play roles in many neurodegenerative diseases including some transmissible spongiform encephalopathies. To address the possible molecular linkage of prion protein (PrP) and tau, a GST-fusion segment of human tau covering the three-repeat region and various PrP segments was used in the tests of GST pull-down and immunoprecipitation. We found tau protein interacted with various style prion proteins such as native prion protein (PrPc) or protease-resistant isoform (PrPSc). Co-localization signals of tau and PrP were found in the CHO cell tranfected with both PrP and tau gene. The domain of interaction with tau was located at N-terminal of PrP (residues 23 to 91). The evidence of molecular interactions between PrP and tau protein highlights a potential role of tau in the biological function of PrP and the pathogenesis of TSEs.
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Affiliation(s)
- Jun Han
- State Key Laboratory for Infectious Diseases Prevention and Control, National Institute for Viral Disease Control and Prevention, Chinese Center for Disease Control and Prevention, Beijing 100052, China
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48
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Kang SW, Rane NS, Kim SJ, Garrison JL, Taunton J, Hegde RS. Substrate-specific translocational attenuation during ER stress defines a pre-emptive quality control pathway. Cell 2006; 127:999-1013. [PMID: 17129784 PMCID: PMC3656606 DOI: 10.1016/j.cell.2006.10.032] [Citation(s) in RCA: 220] [Impact Index Per Article: 12.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2006] [Revised: 08/30/2006] [Accepted: 10/04/2006] [Indexed: 10/23/2022]
Abstract
Eukaryotic proteins entering the secretory pathway are translocated into the ER by signal sequences that vary widely in primary structure. We now provide a functional rationale for this long-observed sequence diversity by demonstrating that differences among signals facilitate substrate-selective modulation of protein translocation. We find that during acute ER stress, translocation of secretory and membrane proteins is rapidly and transiently attenuated in a signal sequence-selective manner. Their cotranslational rerouting to the cytosol for degradation reduces the burden of misfolded substrates entering the ER and represents a pathway for pre-emptive quality control (pQC). Bypassing the pQC pathway for the prion protein increases its rate of aggregation in the ER lumen during prolonged stress and renders cells less capable of viable recovery. Conversely, pharmacologically augmenting pQC during ER stress proved protective. Thus, protein translocation is a physiologically regulated process that is utilized for pQC as part of the ER stress response.
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Affiliation(s)
- Sang-Wook Kang
- Cell Biology and Metabolism Branch, National Institute of Child Health and Human Development, National Institutes of Health, 18 Library Drive, Building 18T, Room 101, Bethesda, MD, 20892, USA
| | - Neena S. Rane
- Cell Biology and Metabolism Branch, National Institute of Child Health and Human Development, National Institutes of Health, 18 Library Drive, Building 18T, Room 101, Bethesda, MD, 20892, USA
| | - Soo Jung Kim
- Functional Genomic Research Center, Korea Research Institute of Bioscience and Biotechnology, Daejeon, 305-333, Korea
| | - Jennifer L. Garrison
- Department of Cellular and Molecular Pharmacology, University of California, San Francisco, San Francisco, CA, 94107, USA
| | - Jack Taunton
- Department of Cellular and Molecular Pharmacology, University of California, San Francisco, San Francisco, CA, 94107, USA
| | - Ramanujan S. Hegde
- Cell Biology and Metabolism Branch, National Institute of Child Health and Human Development, National Institutes of Health, 18 Library Drive, Building 18T, Room 101, Bethesda, MD, 20892, USA
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Abstract
In the world of membrane proteins, topology defines an important halfway house between the amino-acid sequence and the fully folded three-dimensional structure. Although the concept of membrane-protein topology dates back at least 30 years, recent advances in the field of translocon-mediated membrane-protein assembly, proteome-wide studies of membrane-protein topology and an exponentially growing number of high-resolution membrane-protein structures have given us a deeper understanding of how topology is determined and of how it evolves.
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Affiliation(s)
- Gunnar von Heijne
- Center for Biomembrane Research and Stockholm Bioinformatics Center, Department of Biochemistry and Biophysics, Stockholm University, SE-10691 Stockholm.
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Nieznanski K, Podlubnaya ZA, Nieznanska H. Prion protein inhibits microtubule assembly by inducing tubulin oligomerization. Biochem Biophys Res Commun 2006; 349:391-9. [PMID: 16934224 DOI: 10.1016/j.bbrc.2006.08.051] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2006] [Accepted: 08/11/2006] [Indexed: 11/24/2022]
Abstract
A growing body of evidence points to an association of prion protein (PrP) with microtubular cytoskeleton. Recently, direct binding of PrP to tubulin has also been found. In this work, using standard light scattering measurements, sedimentation experiments, and electron microscopy, we show for the first time the effect of a direct interaction between these proteins on tubulin polymerization. We demonstrate that full-length recombinant PrP induces a rapid increase in the turbidity of tubulin diluted below the critical concentration for microtubule assembly. This effect requires magnesium ions and is weakened by NaCl. Moreover, the PrP-induced light scattering structures of tubulin are cold-stable. In preparations of diluted tubulin incubated with PrP, electron microscopy revealed the presence of approximately 50 nm disc-shaped structures not reported so far. These unique tubulin oligomers may form large aggregates. The effect of PrP is more pronounced under the conditions promoting microtubule formation. In these tubulin samples, PrP induces formation of the above oligomers associated with short protofilaments and sheets of protofilaments into aggregates. Noticeably, this is accompanied by a significant reduction of the number and length of microtubules. Hence, we postulate that prion protein may act as an inhibitor of microtubule assembly by inducing formation of stable tubulin oligomers.
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Affiliation(s)
- Krzysztof Nieznanski
- Nencki Institute of Experimental Biology, Department of Muscle Biochemistry, Warsaw, Poland.
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