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Princen K, Van Dooren T, van Gorsel M, Louros N, Yang X, Dumbacher M, Bastiaens I, Coupet K, Dupont S, Cuveliers E, Lauwers A, Laghmouchi M, Vanwelden T, Carmans S, Van Damme N, Duhamel H, Vansteenkiste S, Prerad J, Pipeleers K, Rodiers O, De Ridder L, Claes S, Busschots Y, Pringels L, Verhelst V, Debroux E, Brouwer M, Lievens S, Tavernier J, Farinelli M, Hughes-Asceri S, Voets M, Winderickx J, Wera S, de Wit J, Schymkowitz J, Rousseau F, Zetterberg H, Cummings JL, Annaert W, Cornelissen T, De Winter H, De Witte K, Fivaz M, Griffioen G. Pharmacological modulation of septins restores calcium homeostasis and is neuroprotective in models of Alzheimer's disease. Science 2024; 384:eadd6260. [PMID: 38815015 DOI: 10.1126/science.add6260] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2022] [Accepted: 04/04/2024] [Indexed: 06/01/2024]
Abstract
Abnormal calcium signaling is a central pathological component of Alzheimer's disease (AD). Here, we describe the identification of a class of compounds called ReS19-T, which are able to restore calcium homeostasis in cell-based models of tau pathology. Aberrant tau accumulation leads to uncontrolled activation of store-operated calcium channels (SOCCs) by remodeling septin filaments at the cell cortex. Binding of ReS19-T to septins restores filament assembly in the disease state and restrains calcium entry through SOCCs. In amyloid-β and tau-driven mouse models of disease, ReS19-T agents restored synaptic plasticity, normalized brain network activity, and attenuated the development of both amyloid-β and tau pathology. Our findings identify the septin cytoskeleton as a potential therapeutic target for the development of disease-modifying AD treatments.
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Affiliation(s)
| | | | | | - Nikolaos Louros
- Switch Laboratory, VIB Center for Brain and Disease Research, 3000 Leuven, Belgium
- Switch Laboratory, Department of Cellular and Molecular Medicine, KU Leuven, 3000 Leuven, Belgium
| | - Xiaojuan Yang
- Laboratory for Membrane Trafficking, VIB-Center for Brain and Disease Research and Department of Neurosciences, Leuven Brain Institute, 3000 Leuven, Belgium
| | | | | | | | - Shana Dupont
- reMYND NV, Bio-Incubator, 3001 Leuven-Heverlee, Belgium
| | - Eva Cuveliers
- reMYND NV, Bio-Incubator, 3001 Leuven-Heverlee, Belgium
| | | | | | | | - Sofie Carmans
- reMYND NV, Bio-Incubator, 3001 Leuven-Heverlee, Belgium
| | | | - Hein Duhamel
- reMYND NV, Bio-Incubator, 3001 Leuven-Heverlee, Belgium
| | | | - Jovan Prerad
- reMYND NV, Bio-Incubator, 3001 Leuven-Heverlee, Belgium
| | | | | | | | - Sofie Claes
- reMYND NV, Bio-Incubator, 3001 Leuven-Heverlee, Belgium
| | | | | | | | | | - Marinka Brouwer
- Laboratory of Synapse Biology, VIB Center for Brain & Disease Research and KU Leuven Department of Neurosciences, Leuven Brain Institute, 3000 Leuven, Belgium
| | - Sam Lievens
- Cytokine Receptor Lab, VIB Center for Medical Biotechnology, 9052 Ghent, Belgium
- Department of Biomolecular Medicine, Ghent University, 9000 Ghent, Belgium
| | - Jan Tavernier
- Cytokine Receptor Lab, VIB Center for Medical Biotechnology, 9052 Ghent, Belgium
- Department of Biomolecular Medicine, Ghent University, 9000 Ghent, Belgium
| | | | | | - Marieke Voets
- reMYND NV, Bio-Incubator, 3001 Leuven-Heverlee, Belgium
| | - Joris Winderickx
- reMYND NV, Bio-Incubator, 3001 Leuven-Heverlee, Belgium
- Functional Biology, Department of Biology, KU Leuven, 3001 Leuven-Heverlee, Belgium
| | - Stefaan Wera
- reMYND NV, Bio-Incubator, 3001 Leuven-Heverlee, Belgium
- ViroVet NV, 3001 Leuven-Heverlee, Belgium
| | - Joris de Wit
- Laboratory of Synapse Biology, VIB Center for Brain & Disease Research and KU Leuven Department of Neurosciences, Leuven Brain Institute, 3000 Leuven, Belgium
| | - Joost Schymkowitz
- Switch Laboratory, VIB Center for Brain and Disease Research, 3000 Leuven, Belgium
- Switch Laboratory, Department of Cellular and Molecular Medicine, KU Leuven, 3000 Leuven, Belgium
| | - Frederic Rousseau
- Switch Laboratory, VIB Center for Brain and Disease Research, 3000 Leuven, Belgium
- Switch Laboratory, Department of Cellular and Molecular Medicine, KU Leuven, 3000 Leuven, Belgium
| | - Henrik Zetterberg
- Department of Psychiatry and Neurochemistry, Institute of Neuroscience and Physiology, the Sahlgrenska Academy at the University of Gothenburg, S-431 80 Mölndal, Sweden
- Clinical Neurochemistry Laboratory, Sahlgrenska University Hospital, S-431 80 Mölndal, Sweden
- Department of Neurodegenerative Disease, UCL Queen Square Institute of Neurology, London WC1N 3BG, UK
- UK Dementia Research Institute at UCL, London WC1E 6BT, UK
- Hong Kong Center for Neurodegenerative Diseases, Clear Water Bay, Hong Kong, China
- Wisconsin Alzheimer's Disease Research Center, University of Wisconsin School of Medicine and Public Health, University of Wisconsin-Madison, Madison, WI 53792, USA
| | - Jeffrey L Cummings
- Chambers-Grundy Center for Transformative Neuroscience, Department of Brain Health, School of Integrated Health Sciences, University of Nevada, Las Vegas, Las Vegas, NV 89154, USA
| | - Wim Annaert
- Laboratory for Membrane Trafficking, VIB-Center for Brain and Disease Research and Department of Neurosciences, Leuven Brain Institute, 3000 Leuven, Belgium
| | | | - Hans De Winter
- Laboratory of Medicinal Chemistry, Department of Pharmaceutical Sciences, University of Antwerp, 2610 Wilrijk, Belgium
| | - Koen De Witte
- reMYND NV, Bio-Incubator, 3001 Leuven-Heverlee, Belgium
| | - Marc Fivaz
- reMYND NV, Bio-Incubator, 3001 Leuven-Heverlee, Belgium
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2
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Werner B, Yadav S. Phosphoregulation of the septin cytoskeleton in neuronal development and disease. Cytoskeleton (Hoboken) 2023; 80:275-289. [PMID: 36127729 PMCID: PMC10025170 DOI: 10.1002/cm.21728] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2022] [Revised: 08/13/2022] [Accepted: 09/12/2022] [Indexed: 11/06/2022]
Abstract
Septins are highly conserved GTP-binding proteins that oligomerize and form higher order structures. The septin cytoskeleton plays an important role in cellular organization, intracellular transport, and cytokinesis. Kinase-mediated phosphorylation of septins regulates various aspects of their function, localization, and dynamics. Septins are enriched in the mammalian nervous system where they contribute to neurodevelopment and neuronal function. Emerging research has implicated aberrant changes in septin cytoskeleton in several human diseases. The mechanisms through which aberrant phosphorylation by kinases contributes to septin dysfunction in neurological disorders are poorly understood and represent an important question for future research with therapeutic implications. This review summarizes the current state of knowledge of the diversity of kinases that interact with and phosphorylate mammalian septins, delineates how phosphoregulation impacts septin dynamics, and describes how aberrant septin phosphorylation contributes to neurological disorders.
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Affiliation(s)
- Bailey Werner
- Department of Pharmacology, University of Washington, Seattle, WA, United States
| | - Smita Yadav
- Department of Pharmacology, University of Washington, Seattle, WA, United States
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3
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De Marchi F, Franjkic T, Schito P, Russo T, Nimac J, Chami AA, Mele A, Vidatic L, Kriz J, Julien JP, Apic G, Russell RB, Rogelj B, Cannon JR, Baralle M, Agosta F, Hecimovic S, Mazzini L, Buratti E, Munitic I. Emerging Trends in the Field of Inflammation and Proteinopathy in ALS/FTD Spectrum Disorder. Biomedicines 2023; 11:1599. [PMID: 37371694 PMCID: PMC10295684 DOI: 10.3390/biomedicines11061599] [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: 04/28/2023] [Revised: 05/27/2023] [Accepted: 05/29/2023] [Indexed: 06/29/2023] Open
Abstract
Proteinopathy and neuroinflammation are two main hallmarks of neurodegenerative diseases. They also represent rare common events in an exceptionally broad landscape of genetic, environmental, neuropathologic, and clinical heterogeneity present in patients. Here, we aim to recount the emerging trends in amyotrophic lateral sclerosis (ALS) and frontotemporal degeneration (FTD) spectrum disorder. Our review will predominantly focus on neuroinflammation and systemic immune imbalance in ALS and FTD, which have recently been highlighted as novel therapeutic targets. A common mechanism of most ALS and ~50% of FTD patients is dysregulation of TAR DNA-binding protein 43 (TDP-43), an RNA/DNA-binding protein, which becomes depleted from the nucleus and forms cytoplasmic aggregates in neurons and glia. This, in turn, via both gain and loss of function events, alters a variety of TDP-43-mediated cellular events. Experimental attempts to target TDP-43 aggregates or manipulate crosstalk in the context of inflammation will be discussed. Targeting inflammation, and the immune system in general, is of particular interest because of the high plasticity of immune cells compared to neurons.
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Affiliation(s)
- Fabiola De Marchi
- Department of Neurology and ALS Centre, University of Piemonte Orientale, Maggiore Della Carità Hospital, Corso Mazzini 18, 28100 Novara, Italy; (F.D.M.); (A.M.)
| | - Toni Franjkic
- Laboratory for Molecular Immunology, Department of Biotechnology, University of Rijeka, R. Matejcic 2, 51000 Rijeka, Croatia;
- Metisox, Cambridge CB24 9NL, UK;
| | - Paride Schito
- Department of Neurology & Neuropathology Unit, Institute of Experimental Neurology (INSPE), Division of Neuroscience, IRCCS San Raffaele Scientific Institute, 20132 Milan, Italy; (P.S.); (T.R.)
| | - Tommaso Russo
- Department of Neurology & Neuropathology Unit, Institute of Experimental Neurology (INSPE), Division of Neuroscience, IRCCS San Raffaele Scientific Institute, 20132 Milan, Italy; (P.S.); (T.R.)
| | - Jerneja Nimac
- Department of Biotechnology, Jozef Stefan Institute, SI-1000 Ljubljana, Slovenia; (J.N.); (B.R.)
- Graduate School of Biomedicine, Faculty of Medicine, University of Ljubljana, SI-1000 Ljubljana, Slovenia
| | - Anna A. Chami
- CERVO Research Centre, Laval University, Quebec City, QC G1J 2G3, Canada; (A.A.C.); (J.K.); (J.-P.J.)
| | - Angelica Mele
- Department of Neurology and ALS Centre, University of Piemonte Orientale, Maggiore Della Carità Hospital, Corso Mazzini 18, 28100 Novara, Italy; (F.D.M.); (A.M.)
| | - Lea Vidatic
- Laboratory for Neurodegenerative Disease Research, Division of Molecular Medicine, Ruder Boskovic Institute, 10000 Zagreb, Croatia; (L.V.); (S.H.)
| | - Jasna Kriz
- CERVO Research Centre, Laval University, Quebec City, QC G1J 2G3, Canada; (A.A.C.); (J.K.); (J.-P.J.)
| | - Jean-Pierre Julien
- CERVO Research Centre, Laval University, Quebec City, QC G1J 2G3, Canada; (A.A.C.); (J.K.); (J.-P.J.)
| | | | | | - Boris Rogelj
- Department of Biotechnology, Jozef Stefan Institute, SI-1000 Ljubljana, Slovenia; (J.N.); (B.R.)
- Faculty of Chemistry and Chemical Technology, University of Ljubljana, SI-1000 Ljubljana, Slovenia
| | - Jason R. Cannon
- School of Health Sciences, Purdue University, West Lafayette, IN 47907, USA;
- Purdue Institute for Integrative Neuroscience, Purdue University, West Lafayette, IN 47907, USA
| | | | - Federica Agosta
- Neuroimaging Research Unit, Institute of Experimental Neurology, Division of Neuroscience, IRCCS San Raffaele Scientific Institute, 20132 Milan, Italy;
| | - Silva Hecimovic
- Laboratory for Neurodegenerative Disease Research, Division of Molecular Medicine, Ruder Boskovic Institute, 10000 Zagreb, Croatia; (L.V.); (S.H.)
| | - Letizia Mazzini
- Department of Neurology and ALS Centre, University of Piemonte Orientale, Maggiore Della Carità Hospital, Corso Mazzini 18, 28100 Novara, Italy; (F.D.M.); (A.M.)
| | - Emanuele Buratti
- International Centre for Genetic Engineering and Biotechnology (ICGEB), Padriciano 99, 34149 Trieste, Italy
| | - Ivana Munitic
- Laboratory for Molecular Immunology, Department of Biotechnology, University of Rijeka, R. Matejcic 2, 51000 Rijeka, Croatia;
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Vignaroli F, Mele A, Tondo G, De Giorgis V, Manfredi M, Comi C, Mazzini L, De Marchi F. The Need for Biomarkers in the ALS-FTD Spectrum: A Clinical Point of View on the Role of Proteomics. Proteomes 2023; 11:proteomes11010001. [PMID: 36648959 PMCID: PMC9844364 DOI: 10.3390/proteomes11010001] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2022] [Revised: 12/30/2022] [Accepted: 01/04/2023] [Indexed: 01/11/2023] Open
Abstract
Frontotemporal dementia (FTD) and amyotrophic lateral sclerosis (ALS) are severely debilitating and progressive neurodegenerative disorders. A distinctive pathological feature of several neurodegenerative diseases, including ALS and FTD, is the deposition of aberrant protein inclusions in neuronal cells, which leads to cellular dysfunction and neuronal damage and loss. Despite this, to date, the biological process behind developing these protein inclusions must be better clarified, making the development of disease-modifying treatment impossible until this is done. Proteomics is a powerful tool to characterize the expression, structure, functions, interactions, and modifications of proteins of tissue and biological fluid, including plasma, serum, and cerebrospinal fluid. This protein-profiling characterization aims to identify disease-specific protein alteration or specific pathology-based mechanisms which may be used as markers of these conditions. Our narrative review aims to highlight the need for biomarkers and the potential use of proteomics in clinical practice for ALS-FTD spectrum disorders, considering the emerging rationale in proteomics for new drug development. Certainly, new data will emerge in the near future in this regard and support clinicians in the development of personalized medicine.
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Affiliation(s)
| | - Angelica Mele
- Neurology Unit, Maggiore della Carità Hospital, 28100 Novara, Italy
| | - Giacomo Tondo
- Department of Neurology, S. Andrea Hospital, University of Piemonte Orientale, 13100 Vercelli, Italy
| | - Veronica De Giorgis
- Department of Translational Medicine, University of Piemonte Orientale, 28100 Novara, Italy
- Center for Translational Research and Autoimmune and Allergic Diseases (CAAD), University of Piemonte Orientale, 28100 Novara, Italy
| | - Marcello Manfredi
- Department of Translational Medicine, University of Piemonte Orientale, 28100 Novara, Italy
- Center for Translational Research and Autoimmune and Allergic Diseases (CAAD), University of Piemonte Orientale, 28100 Novara, Italy
| | - Cristoforo Comi
- Department of Neurology, S. Andrea Hospital, University of Piemonte Orientale, 13100 Vercelli, Italy
- Department of Translational Medicine, University of Piemonte Orientale, 28100 Novara, Italy
| | - Letizia Mazzini
- Neurology Unit, Maggiore della Carità Hospital, 28100 Novara, Italy
- Department of Translational Medicine, University of Piemonte Orientale, 28100 Novara, Italy
| | - Fabiola De Marchi
- Neurology Unit, Maggiore della Carità Hospital, 28100 Novara, Italy
- Department of Translational Medicine, University of Piemonte Orientale, 28100 Novara, Italy
- Correspondence: ; Tel.: +39-0321-3733962
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5
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S327 phosphorylation of the presynaptic protein SEPTIN5 increases in the early stages of neurofibrillary pathology and alters the functionality of SEPTIN5. Neurobiol Dis 2022; 163:105603. [DOI: 10.1016/j.nbd.2021.105603] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2021] [Revised: 12/02/2021] [Accepted: 12/22/2021] [Indexed: 12/25/2022] Open
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Molecular Pathways Involved in Frontotemporal Lobar Degeneration with TDP-43 Proteinopathy: What Can We Learn from Proteomics? Int J Mol Sci 2021; 22:ijms221910298. [PMID: 34638637 PMCID: PMC8508653 DOI: 10.3390/ijms221910298] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2021] [Revised: 09/17/2021] [Accepted: 09/22/2021] [Indexed: 12/14/2022] Open
Abstract
Frontotemporal lobar degeneration (FTLD) is a neurodegenerative disorder clinically characterized by behavioral, language, and motor symptoms, with major impact on the lives of patients and their families. TDP-43 proteinopathy is the underlying neuropathological substrate in the majority of cases, referred to as FTLD-TDP. Several genetic causes have been identified, which have revealed some components of its pathophysiology. However, the exact mechanisms driving FTLD-TDP remain largely unknown, forestalling the development of therapies. Proteomic approaches, in particular high-throughput mass spectrometry, hold promise to help elucidate the pathogenic molecular and cellular alterations. In this review, we describe the main findings of the proteomic profiling studies performed on human FTLD-TDP brain tissue. Subsequently, we address the major biological pathways implicated in FTLD-TDP, by reviewing these data together with knowledge derived from genomic and transcriptomic literature. We illustrate that an integrated perspective, encompassing both proteomic, genetic, and transcriptomic discoveries, is vital to unravel core disease processes, and to enable the identification of disease biomarkers and therapeutic targets for this devastating disorder.
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Mendonca P, Taka E, Soliman KFA. Proteomic analysis of the effect of the polyphenol pentagalloyl glucose on proteins involved in neurodegenerative diseases in activated BV‑2 microglial cells. Mol Med Rep 2019; 20:1736-1746. [PMID: 31257500 PMCID: PMC6625426 DOI: 10.3892/mmr.2019.10400] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2018] [Accepted: 05/09/2019] [Indexed: 01/24/2023] Open
Abstract
Neuroinflammation and microglial activation are two important hallmarks of neurodegenerative diseases. Continuous microglial activation may cause the release of several cytotoxic molecules, including many cytokines that are involved in the inflammatory process. Therefore, attenuating inflammation caused by activated microglia may be an approach for the therapeutic management of neurodegenerative diseases. In addition, many studies have reported that polyphenol pentagalloyl glucose (1,2,3,4,6-penta-O-galloyl-β-D-glucose; PGG) is a molecule with potent anti-inflammatory effects, such as inhibiting the release of proinflammatory cytokines. Our previous studies revealed that PGG attenuated the expression of two inflammatory cytokines (murine monocyte chemoattractant protein-5 and pro-metalloproteinase-9) in lipopolysaccharide/interferon γ-activated BV-٢ microglial cells. Additionally, PGG modulated the NF-κB and MAPK signaling pathways by altering genes and proteins, which may affect the MAPK cascade and NF-κB activation. The aim of the present study was to investigate the ability of PGG to modulate the expression of proteins released in activated BV-2 microglial cells, which may be involved in the pathological process of inflammation and neurodegeneration. Proteomic analysis of activated BV-2 cells identified 17 proteins whose expression levels were significantly downregulated by PGG, including septin-7, ataxin-2, and adenylosuccinate synthetase isozyme 2 (ADSS). These proteins were previously described as being highly expressed in neurodegenerative diseases and/or involved in the signaling pathways associated with the formation and growth of neuronal connections and the control of Alzheimer's disease pathogenesis. The inhibitory effect of PGG on ataxin-2, septin-7 and ADSS was further confirmed at the protein and transcriptional levels. Therefore, the obtained results suggest that PGG, with its potent inhibitory effects on ataxin-2, septin-7 and ADSS, may have potential use in the therapeutic management of neurodegenerative diseases.
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Affiliation(s)
- Patricia Mendonca
- College of Pharmacy and Pharmaceutical Sciences, Florida A&M University, Tallahassee, FL 32307, USA
| | - Equar Taka
- College of Pharmacy and Pharmaceutical Sciences, Florida A&M University, Tallahassee, FL 32307, USA
| | - Karam F A Soliman
- College of Pharmacy and Pharmaceutical Sciences, Florida A&M University, Tallahassee, FL 32307, USA
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Hedl TJ, San Gil R, Cheng F, Rayner SL, Davidson JM, De Luca A, Villalva MD, Ecroyd H, Walker AK, Lee A. Proteomics Approaches for Biomarker and Drug Target Discovery in ALS and FTD. Front Neurosci 2019; 13:548. [PMID: 31244593 PMCID: PMC6579929 DOI: 10.3389/fnins.2019.00548] [Citation(s) in RCA: 47] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2019] [Accepted: 05/13/2019] [Indexed: 12/11/2022] Open
Abstract
Neurodegenerative disorders such as amyotrophic lateral sclerosis (ALS) and frontotemporal dementia (FTD) are increasing in prevalence but lack targeted therapeutics. Although the pathological mechanisms behind these diseases remain unclear, both ALS and FTD are characterized pathologically by aberrant protein aggregation and inclusion formation within neurons, which correlates with neurodegeneration. Notably, aggregation of several key proteins, including TAR DNA binding protein of 43 kDa (TDP-43), superoxide dismutase 1 (SOD1), and tau, have been implicated in these diseases. Proteomics methods are being increasingly applied to better understand disease-related mechanisms and to identify biomarkers of disease, using model systems as well as human samples. Proteomics-based approaches offer unbiased, high-throughput, and quantitative results with numerous applications for investigating proteins of interest. Here, we review recent advances in the understanding of ALS and FTD pathophysiology obtained using proteomics approaches, and we assess technical and experimental limitations. We compare findings from various mass spectrometry (MS) approaches including quantitative proteomics methods such as stable isotope labeling by amino acids in cell culture (SILAC) and tandem mass tagging (TMT) to approaches such as label-free quantitation (LFQ) and sequential windowed acquisition of all theoretical fragment ion mass spectra (SWATH-MS) in studies of ALS and FTD. Similarly, we describe disease-related protein-protein interaction (PPI) studies using approaches including immunoprecipitation mass spectrometry (IP-MS) and proximity-dependent biotin identification (BioID) and discuss future application of new techniques including proximity-dependent ascorbic acid peroxidase labeling (APEX), and biotinylation by antibody recognition (BAR). Furthermore, we explore the use of MS to detect post-translational modifications (PTMs), such as ubiquitination and phosphorylation, of disease-relevant proteins in ALS and FTD. We also discuss upstream technologies that enable enrichment of proteins of interest, highlighting the contributions of new techniques to isolate disease-relevant protein inclusions including flow cytometric analysis of inclusions and trafficking (FloIT). These recently developed approaches, as well as related advances yet to be applied to studies of these neurodegenerative diseases, offer numerous opportunities for discovery of potential therapeutic targets and biomarkers for ALS and FTD.
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Affiliation(s)
- Thomas J Hedl
- Neurodegeneration Pathobiology Laboratory, Queensland Brain Institute, The University of Queensland, St Lucia, QLD, Australia
| | - Rebecca San Gil
- Neurodegeneration Pathobiology Laboratory, Queensland Brain Institute, The University of Queensland, St Lucia, QLD, Australia
| | - Flora Cheng
- Centre for Motor Neuron Disease Research, Department of Biomedical Sciences, Faculty of Medicine and Health Sciences, Macquarie University, North Ryde, NSW, Australia
| | - Stephanie L Rayner
- Centre for Motor Neuron Disease Research, Department of Biomedical Sciences, Faculty of Medicine and Health Sciences, Macquarie University, North Ryde, NSW, Australia
| | - Jennilee M Davidson
- Centre for Motor Neuron Disease Research, Department of Biomedical Sciences, Faculty of Medicine and Health Sciences, Macquarie University, North Ryde, NSW, Australia
| | - Alana De Luca
- Centre for Motor Neuron Disease Research, Department of Biomedical Sciences, Faculty of Medicine and Health Sciences, Macquarie University, North Ryde, NSW, Australia
| | - Maria D Villalva
- Centre for Motor Neuron Disease Research, Department of Biomedical Sciences, Faculty of Medicine and Health Sciences, Macquarie University, North Ryde, NSW, Australia
| | - Heath Ecroyd
- School of Chemistry and Molecular Bioscience, University of Wollongong, Wollongong, NSW, Australia.,Illawarra Health and Medical Research Institute, Wollongong, NSW, Australia
| | - Adam K Walker
- Neurodegeneration Pathobiology Laboratory, Queensland Brain Institute, The University of Queensland, St Lucia, QLD, Australia.,Centre for Motor Neuron Disease Research, Department of Biomedical Sciences, Faculty of Medicine and Health Sciences, Macquarie University, North Ryde, NSW, Australia
| | - Albert Lee
- Centre for Motor Neuron Disease Research, Department of Biomedical Sciences, Faculty of Medicine and Health Sciences, Macquarie University, North Ryde, NSW, Australia
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Kurkinen KMA, Marttinen M, Turner L, Natunen T, Mäkinen P, Haapalinna F, Sarajärvi T, Gabbouj S, Kurki M, Paananen J, Koivisto AM, Rauramaa T, Leinonen V, Tanila H, Soininen H, Lucas FR, Haapasalo A, Hiltunen M. SEPT8 modulates β-amyloidogenic processing of APP by affecting the sorting and accumulation of BACE1. J Cell Sci 2016; 129:2224-38. [PMID: 27084579 DOI: 10.1242/jcs.185215] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2015] [Accepted: 04/11/2016] [Indexed: 12/21/2022] Open
Abstract
Dysfunction and loss of synapses are early pathogenic events in Alzheimer's disease. A central step in the generation of toxic amyloid-β (Aβ) peptides is the cleavage of amyloid precursor protein (APP) by β-site APP-cleaving enzyme (BACE1). Here, we have elucidated whether downregulation of septin (SEPT) protein family members, which are implicated in synaptic plasticity and vesicular trafficking, affects APP processing and Aβ generation. SEPT8 was found to reduce soluble APPβ and Aβ levels in neuronal cells through a post-translational mechanism leading to decreased levels of BACE1 protein. In the human temporal cortex, we identified alterations in the expression of specific SEPT8 transcript variants in a manner that correlated with Alzheimer's-disease-related neurofibrillary pathology. These changes were associated with altered β-secretase activity. We also discovered that the overexpression of a specific Alzheimer's-disease-associated SEPT8 transcript variant increased the levels of BACE1 and Aβ peptides in neuronal cells. These changes were related to an increased half-life of BACE1 and the localization of BACE1 in recycling endosomes. These data suggest that SEPT8 modulates β-amyloidogenic processing of APP through a mechanism affecting the intracellular sorting and accumulation of BACE1.
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Affiliation(s)
- Kaisa M A Kurkinen
- Institute of Biomedicine, School of Medicine, University of Eastern Finland, 70211 Kuopio, Finland
| | - Mikael Marttinen
- Institute of Biomedicine, School of Medicine, University of Eastern Finland, 70211 Kuopio, Finland
| | - Laura Turner
- Eisai Ltd., Bernard Katz Building, University College London, London WC1E 6BT, UK
| | - Teemu Natunen
- Institute of Biomedicine, School of Medicine, University of Eastern Finland, 70211 Kuopio, Finland
| | - Petra Mäkinen
- Institute of Biomedicine, School of Medicine, University of Eastern Finland, 70211 Kuopio, Finland
| | - Fanni Haapalinna
- Institute of Clinical Medicine - Neurology, School of Medicine, University of Eastern Finland and Department of Neurology, Kuopio University Hospital, 70211 Kuopio, Finland
| | - Timo Sarajärvi
- Institute of Biomedicine, School of Medicine, University of Eastern Finland, 70211 Kuopio, Finland
| | - Sami Gabbouj
- Institute of Biomedicine, School of Medicine, University of Eastern Finland, 70211 Kuopio, Finland
| | - Mitja Kurki
- Institute of Clinical Medicine - Neurosurgery, School of Medicine, University of Eastern Finland and Neurosurgery of NeuroCenter, Kuopio University Hospital, 70211 Kuopio, Finland
| | - Jussi Paananen
- Institute of Clinical Medicine - Neurosurgery, School of Medicine, University of Eastern Finland and Neurosurgery of NeuroCenter, Kuopio University Hospital, 70211 Kuopio, Finland
| | - Anne M Koivisto
- Institute of Clinical Medicine - Neurology, School of Medicine, University of Eastern Finland and Department of Neurology, Kuopio University Hospital, 70211 Kuopio, Finland
| | - Tuomas Rauramaa
- Institute of Clinical Medicine - Pathology, School of Medicine, University of Eastern Finland and Department of Pathology, Kuopio University Hospital, 70211 Kuopio, Finland
| | - Ville Leinonen
- Institute of Clinical Medicine - Neurosurgery, School of Medicine, University of Eastern Finland and Neurosurgery of NeuroCenter, Kuopio University Hospital, 70211 Kuopio, Finland
| | - Heikki Tanila
- Department of Neurobiology, A.I. Virtanen, Institute for Molecular Sciences, School of Medicine, University of Eastern Finland, 70211 Kuopio, Finland
| | - Hilkka Soininen
- Institute of Clinical Medicine - Neurology, School of Medicine, University of Eastern Finland and Department of Neurology, Kuopio University Hospital, 70211 Kuopio, Finland
| | - Fiona R Lucas
- Eisai Ltd., Bernard Katz Building, University College London, London WC1E 6BT, UK
| | - Annakaisa Haapasalo
- Institute of Clinical Medicine - Neurology, School of Medicine, University of Eastern Finland and Department of Neurology, Kuopio University Hospital, 70211 Kuopio, Finland Department of Neurobiology, A.I. Virtanen, Institute for Molecular Sciences, School of Medicine, University of Eastern Finland, 70211 Kuopio, Finland
| | - Mikko Hiltunen
- Institute of Biomedicine, School of Medicine, University of Eastern Finland, 70211 Kuopio, Finland Institute of Clinical Medicine - Neurology, School of Medicine, University of Eastern Finland and Department of Neurology, Kuopio University Hospital, 70211 Kuopio, Finland
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10
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Owings JP, Kuiper EG, Prezioso SM, Meisner J, Varga JJ, Zelinskaya N, Dammer EB, Duong DM, Seyfried NT, Albertí S, Conn GL, Goldberg JB. Pseudomonas aeruginosa EftM Is a Thermoregulated Methyltransferase. J Biol Chem 2015; 291:3280-90. [PMID: 26677219 DOI: 10.1074/jbc.m115.706853] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2015] [Indexed: 11/06/2022] Open
Abstract
Pseudomonas aeruginosa is a Gram-negative opportunistic pathogen that trimethylates elongation factor-thermo-unstable (EF-Tu) on lysine 5. Lysine 5 methylation occurs in a temperature-dependent manner and is generally only seen when P. aeruginosa is grown at temperatures close to ambient (25 °C) but not at higher temperatures (37 °C). We have previously identified the gene, eftM (for EF-Tu-modifying enzyme), responsible for this modification and shown its activity to be associated with increased bacterial adhesion to and invasion of respiratory epithelial cells. Bioinformatic analyses predicted EftM to be a Class I S-adenosyl-l-methionine (SAM)-dependent methyltransferase. An in vitro methyltransferase assay was employed to show that, in the presence of SAM, EftM directly trimethylates EF-Tu. A natural variant of EftM, with a glycine to arginine substitution at position 50 in the predicted SAM-binding domain, lacks both SAM binding and enzyme activity. Mass spectrometry analysis of the in vitro methyltransferase reaction products revealed that EftM exclusively methylates at lysine 5 of EF-Tu in a distributive manner. Consistent with the in vivo temperature dependence of methylation of EF-Tu, preincubation of EftM at 37 °C abolished methyltransferase activity, whereas this activity was retained when EftM was preincubated at 25 °C. Irreversible protein unfolding at 37 °C was observed, and we propose that this instability is the molecular basis for the temperature dependence of EftM activity. Collectively, our results show that EftM is a thermolabile, SAM-dependent methyltransferase that directly trimethylates lysine 5 of EF-Tu in P. aeruginosa.
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Affiliation(s)
- Joshua P Owings
- From the Department of Pediatrics, Division of Pulmonology, Allergy/Immunology, Cystic Fibrosis and Sleep and the Emory-Children's Center for Cystic Fibrosis Research, Emory University and Children's Healthcare of Atlanta, Atlanta, Georgia 30322, the Department of Microbiology, Immunology, and Cancer Biology, University of Virginia, Charlottesville, Virginia 22908
| | - Emily G Kuiper
- the Department of Biochemistry and the Biochemistry, Cell, and Developmental Biology Program and
| | - Samantha M Prezioso
- From the Department of Pediatrics, Division of Pulmonology, Allergy/Immunology, Cystic Fibrosis and Sleep and the Emory-Children's Center for Cystic Fibrosis Research, Emory University and Children's Healthcare of Atlanta, Atlanta, Georgia 30322, Microbiology and Molecular Genetics Program, Graduate Division of Biological and Biomedical Sciences, Emory University School of Medicine, Atlanta, Georgia 30322, and
| | - Jeffrey Meisner
- From the Department of Pediatrics, Division of Pulmonology, Allergy/Immunology, Cystic Fibrosis and Sleep and the Emory-Children's Center for Cystic Fibrosis Research, Emory University and Children's Healthcare of Atlanta, Atlanta, Georgia 30322
| | - John J Varga
- From the Department of Pediatrics, Division of Pulmonology, Allergy/Immunology, Cystic Fibrosis and Sleep and the Emory-Children's Center for Cystic Fibrosis Research, Emory University and Children's Healthcare of Atlanta, Atlanta, Georgia 30322, the Department of Microbiology, Immunology, and Cancer Biology, University of Virginia, Charlottesville, Virginia 22908
| | | | | | | | | | - Sebastián Albertí
- the Instituto Universitario de Investigación en Ciencias de la Salud, Universidad de las Islas Baleares, Palma de Mallorca, 07122 Spain
| | | | - Joanna B Goldberg
- From the Department of Pediatrics, Division of Pulmonology, Allergy/Immunology, Cystic Fibrosis and Sleep and the Emory-Children's Center for Cystic Fibrosis Research, Emory University and Children's Healthcare of Atlanta, Atlanta, Georgia 30322, the Department of Microbiology, Immunology, and Cancer Biology, University of Virginia, Charlottesville, Virginia 22908,
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11
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Agresta AM, De Palma A, Bardoni A, Salvini R, Iadarola P, Mauri PL. Proteomics as an innovative tool to investigate frontotemporal disorders. Proteomics Clin Appl 2015; 10:457-69. [DOI: 10.1002/prca.201500090] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2015] [Revised: 10/14/2015] [Accepted: 10/28/2015] [Indexed: 12/12/2022]
Affiliation(s)
- Anna Maria Agresta
- Proteomics and Metabolomics Unit; Institute for Biomedical Technologies (ITB-CNR); Segrate (MI) Italy
- Department of Biology and Biotechnologies; Biochemistry Unit; University of Pavia; Pavia Italy
- Doctorate School of Molecular and Translational Medicine; University of Milan; Segrate (MI) Italy
| | - Antonella De Palma
- Proteomics and Metabolomics Unit; Institute for Biomedical Technologies (ITB-CNR); Segrate (MI) Italy
| | - Anna Bardoni
- Biochemistry Unit; Department of Molecular Medicine; University of Pavia; Pavia Italy
| | - Roberta Salvini
- Biochemistry Unit; Department of Molecular Medicine; University of Pavia; Pavia Italy
| | - Paolo Iadarola
- Department of Biology and Biotechnologies; Biochemistry Unit; University of Pavia; Pavia Italy
| | - Pier Luigi Mauri
- Proteomics and Metabolomics Unit; Institute for Biomedical Technologies (ITB-CNR); Segrate (MI) Italy
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12
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Marttinen M, Kurkinen KM, Soininen H, Haapasalo A, Hiltunen M. Synaptic dysfunction and septin protein family members in neurodegenerative diseases. Mol Neurodegener 2015; 10:16. [PMID: 25888325 PMCID: PMC4391194 DOI: 10.1186/s13024-015-0013-z] [Citation(s) in RCA: 83] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2014] [Accepted: 03/23/2015] [Indexed: 11/10/2022] Open
Abstract
Cognitive decline and disease progression in different neurodegenerative diseases typically involves synaptic dysfunction preceding the neuronal loss. The synaptic dysfunction is suggested to be caused by imbalanced synaptic plasticity i.e. enhanced induction of long-term depression and concomitantly decreased long-term potentiation accompanied with excess stimulation of extrasynaptic N-Methyl-D-aspartate (NMDA) receptors due to various disturbances in pre- and postsynaptic sites. Recent research has identified neurodegenerative disease-related changes in protein accumulation and aggregation, gene expression, and protein functions, which may contribute to imbalanced synaptic function. Nevertheless, a comprehensive understanding of the mechanisms regulating synaptic plasticity in health and disease is still lacking and therefore characterization of new candidates involved in these mechanisms is needed. Septins, a highly conserved group of guanosine-5'-triphosphate (GTP)-binding proteins, show high neuronal expression and are implicated in the regulation of synaptic vesicle trafficking and neurotransmitter release. In this review, we first summarize the evidence how synaptic dysfunction is related to the pathogenesis of Alzheimer's, Parkinson's and Huntington's disease and frontotemporal lobar degeneration. Then, we discuss different aspects of the potential involvement of the septin family members in the regulation of synaptic function in relation to the pathogenesis of neurodegenerative diseases.
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Affiliation(s)
- Mikael Marttinen
- Institute of Biomedicine, University of Eastern Finland, P.O. Box 1627, 70211, Kuopio, Finland. .,Institute of Clinical Medicine - Neurology, University of Eastern Finland, Kuopio, Finland. .,Department of Neurology, Kuopio University Hospital, Kuopio, Finland.
| | - Kaisa Ma Kurkinen
- Institute of Biomedicine, University of Eastern Finland, P.O. Box 1627, 70211, Kuopio, Finland. .,Institute of Clinical Medicine - Neurology, University of Eastern Finland, Kuopio, Finland. .,Department of Neurology, Kuopio University Hospital, Kuopio, Finland.
| | - Hilkka Soininen
- Institute of Clinical Medicine - Neurology, University of Eastern Finland, Kuopio, Finland. .,Department of Neurology, Kuopio University Hospital, Kuopio, Finland.
| | - Annakaisa Haapasalo
- Institute of Clinical Medicine - Neurology, University of Eastern Finland, Kuopio, Finland. .,Department of Neurology, Kuopio University Hospital, Kuopio, Finland.
| | - Mikko Hiltunen
- Institute of Biomedicine, University of Eastern Finland, P.O. Box 1627, 70211, Kuopio, Finland. .,Institute of Clinical Medicine - Neurology, University of Eastern Finland, Kuopio, Finland. .,Department of Neurology, Kuopio University Hospital, Kuopio, Finland.
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13
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Bai B, Chen PC, Hales CM, Wu Z, Pagala V, High AA, Levey AI, Lah JJ, Peng J. Integrated approaches for analyzing U1-70K cleavage in Alzheimer's disease. J Proteome Res 2014; 13:4526-34. [PMID: 24902715 PMCID: PMC4227550 DOI: 10.1021/pr5003593] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
![]()
The
accumulation of pathologic protein fragments is common in neurodegenerative
disorders. We have recently identified in Alzheimer’s disease
(AD) the aggregation of the U1-70K splicing factor and abnormal RNA
processing. Here, we present that U1-70K can be cleaved into an N-terminal
truncation (N40K) in ∼50% of AD cases, and the N40K abundance
is inversely proportional to the total level of U1-70K. To map the
cleavage site, we compared tryptic peptides of N40K and stable isotope
labeled U1-70K by liquid chromatography–tandem mass spectrometry
(MS), revealing that the proteolysis site is located in a highly repetitive
and hydrophilic domain of U1-70K. We then adapted Western blotting
to map the cleavage site in two steps: (i) mass spectrometric analysis
revealing that U1-70K and N40K share the same N-termini and contain
no major modifications; (ii) matching N40K with a series of six recombinant
U1-70K truncations to define the cleavage site within a small region
(Arg300 ± 6 residues). Finally, N40K expression led to substantial
degeneration of rat primary hippocampal neurons. In summary, we combined
multiple approaches to identify the U1-70K proteolytic site and found
that the N40K fragment might contribute to neuronal toxicity in Alzheimer’s
disease.
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Affiliation(s)
- Bing Bai
- Departments of Structural Biology and Developmental Neurobiology, ‡St. Jude Proteomics Facility, St. Jude Children's Research Hospital , Memphis, Tennessee 38105, United States
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14
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Hales CM, Dammer EB, Diner I, Yi H, Seyfried NT, Gearing M, Glass JD, Montine TJ, Levey AI, Lah JJ. Aggregates of small nuclear ribonucleic acids (snRNAs) in Alzheimer's disease. Brain Pathol 2014; 24:344-51. [PMID: 24571648 DOI: 10.1111/bpa.12133] [Citation(s) in RCA: 68] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2013] [Accepted: 02/13/2014] [Indexed: 01/04/2023] Open
Abstract
We recently discovered that protein components of the ribonucleic acid (RNA) spliceosome form cytoplasmic aggregates in Alzheimer's disease (AD) brain, resulting in widespread changes in RNA splicing. However, the involvement of small nuclear RNAs (snRNAs), also key components of the spliceosome complex, in the pathology of AD remains unknown. Using immunohistochemical staining of post-mortem human brain and spinal cord, we identified cytoplasmic tangle-shaped aggregates of snRNA in both sporadic and familial AD cases but not in aged controls or other neurodegenerative disorders. Immunofluorescence using antibodies reactive with the 2,2,7-trimethylguanosine cap of snRNAs and transmission electron microscopy demonstrated snRNA localization with tau and paired helical filaments, the main component of neurofibrillary tangles. Quantitative real-time polymerase chain reaction (PCR) showed U1 snRNA accumulation in the insoluble fraction of AD brains whereas other U snRNAs were not enriched. In combination with our previous results, these findings demonstrate that aggregates of U1 snRNA and U1 small nuclear ribonucleoproteins represent a new pathological hallmark of AD.
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Affiliation(s)
- Chadwick M Hales
- Center for Neurodegenerative Disease, Emory University, Atlanta, GA; Department of Neurology, Emory University School of Medicine, Atlanta, GA
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15
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Zakas PM, Gangadharan B, Almeida-Porada G, Porada CD, Spencer HT, Doering CB. Development and characterization of recombinant ovine coagulation factor VIII. PLoS One 2012; 7:e49481. [PMID: 23152911 PMCID: PMC3494657 DOI: 10.1371/journal.pone.0049481] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2012] [Accepted: 10/09/2012] [Indexed: 11/18/2022] Open
Abstract
Animal models of the bleeding disorder, hemophilia A, have been an integral component of the biopharmaceutical development process and have facilitated the development of recombinant coagulation factor VIII (fVIII) products capable of restoring median survival of persons with hemophilia A to that of the general population. However, there remain several limitations to recombinant fVIII as a biotherapeutic, including invasiveness of intravenous infusion, short half-life, immunogenicity, and lack of availability to the majority of the world's population. The recently described ovine model of hemophilia A is the largest and most accurate phenocopy. Affected sheep die prematurely due to bleeding-related pathogenesis and display robust adaptive humoral immunity to non-ovine fVIII. Herein, we describe the development and characterization of recombinant ovine fVIII (ofVIII) to support further the utility of the ovine hemophilia A model. Full-length and B-domain deleted (BDD) ofVIII cDNAs were generated and demonstrated to facilitate greater biosynthetic rates than their human fVIII counterparts while both BDD constructs showed greater expression rates than the same-species full-length versions. A top recombinant BDD ofVIII producing baby hamster kidney clone was identified and used to biosynthesize raw material for purification and biochemical characterization. Highly purified recombinant BDD ofVIII preparations possess a specific activity nearly 2-fold higher than recombinant BDD human fVIII and display a differential glycosylation pattern. However, binding to the carrier protein, von Willebrand factor, which is critical for stability of fVIII in circulation, is indistinguishable. Decay of thrombin-activated ofVIIIa is 2-fold slower than human fVIII indicating greater intrinsic stability. Furthermore, intravenous administration of ofVIII effectively reverses the bleeding phenotype in the murine model of hemophilia A. Recombinant ofVIII should facilitate the maintenance of the ovine hemophilia A herd and their utilization as a relevant large animal model for the research and development of novel nucleic acid and protein-based therapies for hemophilia A.
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Affiliation(s)
- Philip M. Zakas
- Graduate Program in Molecular and Systems Pharmacology, Emory University, Atlanta, Georgia, United States of America
| | - Bagirath Gangadharan
- Aflac Cancer and Blood Disorders Center, Department of Pediatrics, Emory University School of Medicine, Atlanta, Georgia, United States of America
| | - Graca Almeida-Porada
- Wake Forest Institute for Regenerative Medicine, Winston-Salem, North Carolina, United States of America
| | - Christopher D. Porada
- Wake Forest Institute for Regenerative Medicine, Winston-Salem, North Carolina, United States of America
| | - H. Trent Spencer
- Aflac Cancer and Blood Disorders Center, Department of Pediatrics, Emory University School of Medicine, Atlanta, Georgia, United States of America
| | - Christopher B. Doering
- Aflac Cancer and Blood Disorders Center, Department of Pediatrics, Emory University School of Medicine, Atlanta, Georgia, United States of America
- * E-mail:
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16
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Jones CL, Sampson TR, Nakaya HI, Pulendran B, Weiss DS. Repression of bacterial lipoprotein production by Francisella novicida facilitates evasion of innate immune recognition. Cell Microbiol 2012; 14:1531-43. [PMID: 22632124 DOI: 10.1111/j.1462-5822.2012.01816.x] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2012] [Revised: 05/04/2012] [Accepted: 05/15/2012] [Indexed: 01/04/2023]
Abstract
Innate recognition systems, including the Toll-like receptors (TLRs), play a critical role in activating host defences and proinflammatory pathways in response to infection. Pathogens have developed strategies to subvert TLRs in order to survive and replicate within the host. The model intracellular pathogen, Francisella novicida, modulates host defences to promote survival and replication in macrophages. TLR2, which recognizes bacterial lipoproteins (BLPs), is critical for activating host defences and proinflammatory cytokine production in response to Francisella infection. Here we show that the F. novicida protein FTN_0757 acts to repress BLP production, dampening TLR2 activation. The ΔFTN_0757 mutant strain induced robust TLR2-dependent cytokine production in macrophages compared with wild-type bacteria, and produced increased amounts of BLPs. The deletion of one BLP (FTN_1103) from ΔFTN_0757 decreased the total BLP concentration to near wild-type level sand correlated with a decrease in the inductionof TLR2 signalling. The overproduction of BLPs also contributed to the in vivo attenuation of the ΔFTN_0757 mutant, which was significantly rescued when FTN_1103 was deleted. Taken together, these data reveal a novel mechanism of immune evasion by the downregulation of BLP expression to subvert TLR2 activation, which is likely used by numerous other intracellular bacterial pathogens.
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Affiliation(s)
- Crystal L Jones
- Department of Microbiology and Immunology, Microbiology and Molecular Genetics Program, Emory University, Atlanta, GA, USA
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