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D'Acunto E, Fra A, Visentin C, Manno M, Ricagno S, Galliciotti G, Miranda E. Neuroserpin: structure, function, physiology and pathology. Cell Mol Life Sci 2021; 78:6409-6430. [PMID: 34405255 PMCID: PMC8558161 DOI: 10.1007/s00018-021-03907-6] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2021] [Revised: 07/23/2021] [Accepted: 07/27/2021] [Indexed: 12/24/2022]
Abstract
Neuroserpin is a serine protease inhibitor identified in a search for proteins implicated in neuronal axon growth and synapse formation. Since its discovery over 30 years ago, it has been the focus of active research. Many efforts have concentrated in elucidating its neuroprotective role in brain ischemic lesions, the structural bases of neuroserpin conformational change and the effects of neuroserpin polymers that underlie the neurodegenerative disease FENIB (familial encephalopathy with neuroserpin inclusion bodies), but the investigation of the physiological roles of neuroserpin has increased over the last years. In this review, we present an updated and critical revision of the current literature dealing with neuroserpin, covering all aspects of research including the expression and physiological roles of neuroserpin, both inside and outside the nervous system; its inhibitory and non-inhibitory mechanisms of action; the molecular structure of the monomeric and polymeric conformations of neuroserpin, including a detailed description of the polymerisation mechanism; and the involvement of neuroserpin in human disease, with particular emphasis on FENIB. Finally, we briefly discuss the identification by genome-wide screening of novel neuroserpin variants and their possible pathogenicity.
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Affiliation(s)
- Emanuela D'Acunto
- Department of Biology and Biotechnologies 'Charles Darwin', Sapienza University of Rome, Rome, Italy
| | - Annamaria Fra
- Department of Molecular and Translational Medicine, University of Brescia, Brescia, Italy
| | - Cristina Visentin
- Department of Biosciences, University of Milan, Milan, Italy
- Institute of Molecular and Translational Cardiology, I.R.C.C.S. Policlinico San Donato, Milan, Italy
| | - Mauro Manno
- Institute of Biophysics, National Research Council of Italy, Palermo, Italy
| | - Stefano Ricagno
- Department of Biosciences, University of Milan, Milan, Italy
| | - Giovanna Galliciotti
- Institute of Neuropathology, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - Elena Miranda
- Department of Biology and Biotechnologies 'Charles Darwin', Sapienza University of Rome, Rome, Italy.
- Pasteur Institute-Cenci Bolognetti Foundation, Sapienza University of Rome, Rome, Italy.
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2
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Eggenschwiler R, Patronov A, Hegermann J, Fráguas-Eggenschwiler M, Wu G, Cortnumme L, Ochs M, Antes I, Cantz T. A combined in silico and in vitro study on mouse Serpina1a antitrypsin-deficiency mutants. Sci Rep 2019; 9:7486. [PMID: 31097772 PMCID: PMC6522476 DOI: 10.1038/s41598-019-44043-3] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2018] [Accepted: 05/07/2019] [Indexed: 01/15/2023] Open
Abstract
Certain point-mutations in the human SERPINA1-gene can cause severe α1-antitrypsin-deficiency (A1AT-D). Affected individuals can suffer from loss-of-function lung-disease and from gain-of-function liver-disease phenotypes. However, age of onset and severity of clinical appearance is heterogeneous amongst carriers, suggesting involvement of additional genetic and environmental factors. The generation of authentic A1AT-D mouse-models has been hampered by the complexity of the mouse Serpina1-gene locus and a model with concurrent lung and liver-disease is still missing. Here, we investigate point-mutations in the mouse Serpina1a antitrypsin-orthologue, which are homolog-equivalent to ones known to cause severe A1AT-D in human. We combine in silico and in vitro methods and we find that analyzed mutations do introduce potential disease-causing properties into Serpina1a. Finally, we show that introduction of the King’s-mutation causes inactivation of neutrophil elastase inhibitory-function in both, mouse and human antitrypsin, while the mouse Z-mutant retains activity. This work paves the path to generation of better A1AT-D mouse-models.
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Affiliation(s)
- Reto Eggenschwiler
- Research Group Translational Hepatology and Stem Cell Biology, Cluster of Excellence REBIRTH, Hannover Medical School, Hannover, 30625, Germany. .,Department of Gastroenterology, Hepatology and Endocrinology, Hannover Medical School, Hannover, 30625, Germany.
| | - Atanas Patronov
- Protein Modelling Group, Department of Life Sciences, Technical University Munich, Freising, 85354, Germany.,TUM School of Life Sciences, Center for Integrated Protein Science (CIPSM), Technical University Munich, Freising, 85354, Germany
| | - Jan Hegermann
- Research Core Unit Electron Microscopy, Hannover Medical School, Hannover, 30625, Germany.,Institute of Functional and Applied Anatomy, Hannover Medical School, Hannover, 30625, Germany.,Imaging Platform of the Cluster of Excellence REBIRTH, Hannover Medical School, Hannover, 30625, Germany
| | - Mariane Fráguas-Eggenschwiler
- Department of Gastroenterology, Hepatology and Endocrinology, Hannover Medical School, Hannover, 30625, Germany.,TWINCORE, Centre for Experimental and Clinical Infection Research, Hannover, 30625, Germany
| | - Guangming Wu
- Max Planck Institute for Molecular Biomedicine, Cell and Developmental Biology, Münster, 48149, Germany
| | - Leon Cortnumme
- Research Group Translational Hepatology and Stem Cell Biology, Cluster of Excellence REBIRTH, Hannover Medical School, Hannover, 30625, Germany.,Department of Gastroenterology, Hepatology and Endocrinology, Hannover Medical School, Hannover, 30625, Germany
| | - Matthias Ochs
- Research Core Unit Electron Microscopy, Hannover Medical School, Hannover, 30625, Germany.,Institute of Functional and Applied Anatomy, Hannover Medical School, Hannover, 30625, Germany.,Imaging Platform of the Cluster of Excellence REBIRTH, Hannover Medical School, Hannover, 30625, Germany.,Institute of Vegetative Anatomy Charité - Universitaetsmedizin Berlin, Berlin, 10115, Germany
| | - Iris Antes
- Protein Modelling Group, Department of Life Sciences, Technical University Munich, Freising, 85354, Germany.,TUM School of Life Sciences, Center for Integrated Protein Science (CIPSM), Technical University Munich, Freising, 85354, Germany
| | - Tobias Cantz
- Research Group Translational Hepatology and Stem Cell Biology, Cluster of Excellence REBIRTH, Hannover Medical School, Hannover, 30625, Germany. .,Department of Gastroenterology, Hepatology and Endocrinology, Hannover Medical School, Hannover, 30625, Germany. .,Max Planck Institute for Molecular Biomedicine, Cell and Developmental Biology, Münster, 48149, Germany.
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3
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Socias SB, González-Lizárraga F, Avila CL, Vera C, Acuña L, Sepulveda-Diaz JE, Del-Bel E, Raisman-Vozari R, Chehin RN. Exploiting the therapeutic potential of ready-to-use drugs: Repurposing antibiotics against amyloid aggregation in neurodegenerative diseases. Prog Neurobiol 2017; 162:17-36. [PMID: 29241812 DOI: 10.1016/j.pneurobio.2017.12.002] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2017] [Revised: 12/07/2017] [Accepted: 12/07/2017] [Indexed: 01/02/2023]
Abstract
Neurodegenerative diseases are chronic and progressive disorders that affect specific regions of the brain, causing gradual disability and suffering that results in a complete inability of patients to perform daily functions. Amyloid aggregation of specific proteins is the most common biological event that is responsible for neuronal death and neurodegeneration in various neurodegenerative diseases. Therapeutic agents capable of interfering with the abnormal aggregation are required, but traditional drug discovery has fallen short. The exploration of new uses for approved drugs provides a useful alternative to fill the gap between the increasing incidence of neurodegenerative diseases and the long-term assessment of classical drug discovery technologies. Drug re-profiling is currently the quickest possible transition from bench to bedside. In this way, experimental evidence shows that some antibiotic compounds exert neuroprotective action through anti-aggregating activity on disease-associated proteins. The finding that many antibiotics can cross the blood-brain barrier and have been used for several decades without serious toxic effects makes them excellent candidates for therapeutic switching towards neurological disorders. The present review is, to our knowledge, the first extensive evaluation and analysis of the anti-amyloidogenic effect of different antibiotics on well-known disease-associated proteins. In addition, we propose a common structural signature derived from the antiaggregant antibiotic molecules that could be relevant to rational drug discovery.
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Affiliation(s)
- Sergio B Socias
- Instituto Superior de Investigaciones Biológicas (INSIBIO), CONICET-UNT, and Instituto de Química Biológica "Dr. Bernabé Bloj", Facultad de Bioquímica, Química y Farmacia, UNT. Chacabuco 461, T4000ILI, San Miguel de Tucumán, Argentina, Argentina
| | - Florencia González-Lizárraga
- Instituto Superior de Investigaciones Biológicas (INSIBIO), CONICET-UNT, and Instituto de Química Biológica "Dr. Bernabé Bloj", Facultad de Bioquímica, Química y Farmacia, UNT. Chacabuco 461, T4000ILI, San Miguel de Tucumán, Argentina, Argentina
| | - Cesar L Avila
- Instituto Superior de Investigaciones Biológicas (INSIBIO), CONICET-UNT, and Instituto de Química Biológica "Dr. Bernabé Bloj", Facultad de Bioquímica, Química y Farmacia, UNT. Chacabuco 461, T4000ILI, San Miguel de Tucumán, Argentina, Argentina
| | - Cecilia Vera
- Instituto Superior de Investigaciones Biológicas (INSIBIO), CONICET-UNT, and Instituto de Química Biológica "Dr. Bernabé Bloj", Facultad de Bioquímica, Química y Farmacia, UNT. Chacabuco 461, T4000ILI, San Miguel de Tucumán, Argentina, Argentina
| | - Leonardo Acuña
- Instituto Superior de Investigaciones Biológicas (INSIBIO), CONICET-UNT, and Instituto de Química Biológica "Dr. Bernabé Bloj", Facultad de Bioquímica, Química y Farmacia, UNT. Chacabuco 461, T4000ILI, San Miguel de Tucumán, Argentina, Argentina; Sorbonne Universite, UPMC Univ Paris 06, INSERM, CNRS, UM75, U1127, UMR 7225, Institut du Cerveau et de la Moelle Epinière, Paris, France
| | - Julia E Sepulveda-Diaz
- Sorbonne Universite, UPMC Univ Paris 06, INSERM, CNRS, UM75, U1127, UMR 7225, Institut du Cerveau et de la Moelle Epinière, Paris, France
| | - Elaine Del-Bel
- Department of Morphology, Physiology and Stomatology, Faculty of Odontology of Ribeirão Preto, University of São Paulo, Brazil; Center of Interdisciplinary Research on Applied Neurosciences (NAPNA), University of São Paulo, Brazil
| | - Rita Raisman-Vozari
- Sorbonne Universite, UPMC Univ Paris 06, INSERM, CNRS, UM75, U1127, UMR 7225, Institut du Cerveau et de la Moelle Epinière, Paris, France.
| | - Rosana N Chehin
- Instituto Superior de Investigaciones Biológicas (INSIBIO), CONICET-UNT, and Instituto de Química Biológica "Dr. Bernabé Bloj", Facultad de Bioquímica, Química y Farmacia, UNT. Chacabuco 461, T4000ILI, San Miguel de Tucumán, Argentina, Argentina.
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4
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Nallagangula KS, Shashidhar K, Lakshmaiah V, Muninarayana C. Cirrhosis of liver: Interference of serpins in quantification of SERPINA4 - A preliminary study. Pract Lab Med 2017; 9:53-57. [PMID: 29159256 PMCID: PMC5683666 DOI: 10.1016/j.plabm.2017.10.002] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2017] [Revised: 08/28/2017] [Accepted: 10/06/2017] [Indexed: 01/12/2023] Open
Abstract
BACKGROUND Cirrhosis of liver is a pathological condition, wherein functions of liver are impaired by chronic liver exploitations. Due to decrease in synthetic capacity, expressions of plasma proteins tend to decrease in blood stream. Serpins (Serine protease inhibitors) are class of plasma proteins expressed from liver with structural similarities and diverse functions. SERPINA4 (Kallistatin) is a multifunctional serpin clade A protein expressed from liver and concentration in serum is the reflection of extent of liver dysfunction. OBJECTIVE To identify interference of other serpins by immunological cross reactivity with SERPINA4 in cirrhotic liver and healthy subjects. MATERIALS AND METHODS Blood samples were collected from 20 subjects (10 cirrhotic liver, 10 healthy) from R.L. Jalappa Hospital and Research Centre, Kolar, Karnataka, India. Separation of proteins was carried out by SDS-PAGE. Cross reactivity study was analyzed using western blot. RESULTS Proteins present in cirrhotic liver and healthy subject's serum were separated by SDS PAGE. There was no band detection on both (cirrhotic liver and healthy) PVDF (polyvinylidene diflouride) membranes. However, a significant band was observed with recombinant kallistatin. CONCLUSION Structurally similar serpins with minor amino acid sequence similarities did not show any immunological cross reactivity with SERPINA4 due to non identical epitope in cirrhotic liver and healthy subjects. Present study revealed that there is no interference of serpins for immunological reactions in quantitative estimation of kallistatin which needs further validation.
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Affiliation(s)
| | - K.N. Shashidhar
- Department of Biochemistry, Sri Devaraj Urs Medical College, SDUAHER, Tamaka, Kolar, Karnataka, India
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Ali MF, Kaushik A, Kapil C, Gupta D, Jairajpuri MA. A hydrophobic patch surrounding Trp154 in human neuroserpin controls the helix F dynamics with implications in inhibition and aggregation. Sci Rep 2017; 7:42987. [PMID: 28230174 PMCID: PMC5322333 DOI: 10.1038/srep42987] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2016] [Accepted: 01/17/2017] [Indexed: 01/23/2023] Open
Abstract
Neuroserpin (NS) mediated inhibition of tissue-type plasminogen activator (tPA) is important for brain development, synapse formation and memory. Aberrations in helix F and β-sheet A movement during inhibition can directly lead to epilepsy or dementia. Conserved W154 residue in a hydrophobic patch between helix F and β-sheet A is ideally placed to control their movement during inhibition. Molecular Dynamics (MD) simulation on wild type (WT) NS and its two variants (W154A and W154P) demonstrated partial deformation in helix F and conformational differences in strands 1A and 2A only in W154P. A fluorescence and Circular Dichroism (CD) analysis with purified W154 variants revealed a significant red-shift and an increase in α-helical content in W154P as compared to W154A and WT NS. Kinetics of tPA inhibition showed a decline in association rates (ka) for W154A as compared to WT NS with indication of complex formation. Appearance of cleaved without complex formation in W154P indicates that the variant acts as substrate due to conformational misfolding around helix F. Both the variants however showed increased rate of aggregation as compared to WT NS. The hydrophobic patch identified in this study may have importance in helix F dynamics of NS.
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Affiliation(s)
- Mohammad Farhan Ali
- Protein Conformation and Enzymology Lab, Department of Biosciences, Jamia Millia Islamia (A Central University), New Delhi-110025, India
| | - Abhinav Kaushik
- Translational Bioinformatics Group, International Centre for Genetic Engineering and Biotechnology (ICGEB), Aruna Asaf Ali Marg, New Delhi-110067, India
| | - Charu Kapil
- Protein Conformation and Enzymology Lab, Department of Biosciences, Jamia Millia Islamia (A Central University), New Delhi-110025, India
| | - Dinesh Gupta
- Translational Bioinformatics Group, International Centre for Genetic Engineering and Biotechnology (ICGEB), Aruna Asaf Ali Marg, New Delhi-110067, India
| | - Mohamad Aman Jairajpuri
- Protein Conformation and Enzymology Lab, Department of Biosciences, Jamia Millia Islamia (A Central University), New Delhi-110025, India
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6
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Porebski BT, Keleher S, Hollins JJ, Nickson AA, Marijanovic EM, Borg NA, Costa MGS, Pearce MA, Dai W, Zhu L, Irving JA, Hoke DE, Kass I, Whisstock JC, Bottomley SP, Webb GI, McGowan S, Buckle AM. Smoothing a rugged protein folding landscape by sequence-based redesign. Sci Rep 2016; 6:33958. [PMID: 27667094 PMCID: PMC5036219 DOI: 10.1038/srep33958] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2016] [Accepted: 09/01/2016] [Indexed: 11/09/2022] Open
Abstract
The rugged folding landscapes of functional proteins puts them at risk of misfolding and aggregation. Serine protease inhibitors, or serpins, are paradigms for this delicate balance between function and misfolding. Serpins exist in a metastable state that undergoes a major conformational change in order to inhibit proteases. However, conformational labiality of the native serpin fold renders them susceptible to misfolding, which underlies misfolding diseases such as α1-antitrypsin deficiency. To investigate how serpins balance function and folding, we used consensus design to create conserpin, a synthetic serpin that folds reversibly, is functional, thermostable, and polymerization resistant. Characterization of its structure, folding and dynamics suggest that consensus design has remodeled the folding landscape to reconcile competing requirements for stability and function. This approach may offer general benefits for engineering functional proteins that have risky folding landscapes, including the removal of aggregation-prone intermediates, and modifying scaffolds for use as protein therapeutics.
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Affiliation(s)
- Benjamin T Porebski
- Biomedicine Discovery Institute, Department of Biochemistry and Molecular Biology, Monash University, Clayton, Victoria 3800, Australia.,Medical Research Council Laboratory of Molecular Biology, Francis Crick Avenue, Cambridge, CB2 0QH, United Kingdom
| | - Shani Keleher
- Biomedicine Discovery Institute, Department of Biochemistry and Molecular Biology, Monash University, Clayton, Victoria 3800, Australia
| | - Jeffrey J Hollins
- Department of Chemistry, University of Cambridge, Lensfield Road, Cambridge, CB2 1EW, United Kingdom
| | - Adrian A Nickson
- Department of Chemistry, University of Cambridge, Lensfield Road, Cambridge, CB2 1EW, United Kingdom
| | - Emilia M Marijanovic
- Biomedicine Discovery Institute, Department of Biochemistry and Molecular Biology, Monash University, Clayton, Victoria 3800, Australia
| | - Natalie A Borg
- Biomedicine Discovery Institute, Department of Biochemistry and Molecular Biology, Monash University, Clayton, Victoria 3800, Australia
| | - Mauricio G S Costa
- Programa de Computação Científica, Fundação Oswaldo Cruz, 21949900 Rio de Janeiro, Brazil
| | - Mary A Pearce
- Biomedicine Discovery Institute, Department of Biochemistry and Molecular Biology, Monash University, Clayton, Victoria 3800, Australia
| | - Weiwen Dai
- Biomedicine Discovery Institute, Department of Biochemistry and Molecular Biology, Monash University, Clayton, Victoria 3800, Australia
| | - Liguang Zhu
- Faculty of Information Technology, Monash University, Clayton, Victoria 3800, Australia
| | - James A Irving
- Wolfson Institute for Biomedical Research, University College London, Gower Street, London, WC1E 6BT, United Kingdom
| | - David E Hoke
- Biomedicine Discovery Institute, Department of Biochemistry and Molecular Biology, Monash University, Clayton, Victoria 3800, Australia
| | - Itamar Kass
- Biomedicine Discovery Institute, Department of Biochemistry and Molecular Biology, Monash University, Clayton, Victoria 3800, Australia
| | - James C Whisstock
- Biomedicine Discovery Institute, Department of Biochemistry and Molecular Biology, Monash University, Clayton, Victoria 3800, Australia.,ARC Centre of Excellence in Advanced Molecular Imaging, Monash University, Clayton, Victoria 3800, Australia
| | - Stephen P Bottomley
- Biomedicine Discovery Institute, Department of Biochemistry and Molecular Biology, Monash University, Clayton, Victoria 3800, Australia
| | - Geoffrey I Webb
- Faculty of Information Technology, Monash University, Clayton, Victoria 3800, Australia
| | - Sheena McGowan
- Biomedicine Discovery Institute, Department of Biochemistry and Molecular Biology, Monash University, Clayton, Victoria 3800, Australia.,Biomedicine Discovery Institute, Department of Microbiology, Monash University, Clayton, Victoria 3800, Australia
| | - Ashley M Buckle
- Biomedicine Discovery Institute, Department of Biochemistry and Molecular Biology, Monash University, Clayton, Victoria 3800, Australia
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Moriconi C, Ordoñez A, Lupo G, Gooptu B, Irving JA, Noto R, Martorana V, Manno M, Timpano V, Guadagno NA, Dalton L, Marciniak SJ, Lomas DA, Miranda E. Interactions between N-linked glycosylation and polymerisation of neuroserpin within the endoplasmic reticulum. FEBS J 2015; 282:4565-79. [PMID: 26367528 PMCID: PMC4949553 DOI: 10.1111/febs.13517] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2014] [Revised: 07/26/2015] [Accepted: 09/10/2015] [Indexed: 01/04/2023]
Abstract
The neuronal serpin neuroserpin undergoes polymerisation as a consequence of point mutations that alter its conformational stability, leading to a neurodegenerative dementia called familial encephalopathy with neuroserpin inclusion bodies (FENIB). Neuroserpin is a glycoprotein with predicted glycosylation sites at asparagines 157, 321 and 401. We used site-directed mutagenesis, transient transfection, western blot, metabolic labelling and ELISA to probe the relationship between glycosylation, folding, polymerisation and degradation of neuroserpin in validated cell models of health and disease. Our data show that glycosylation at N157 and N321 plays an important role in maintaining the monomeric state of neuroserpin, and we propose this is the result of steric hindrance or effects on local conformational dynamics that can contribute to polymerisation. Asparagine residue 401 is not glycosylated in wild type neuroserpin and in several polymerogenic variants that cause FENIB, but partial glycosylation was observed in the G392E mutant of neuroserpin that causes severe, early-onset dementia. Our findings indicate that N401 glycosylation reports lability of the C-terminal end of neuroserpin in its native state. This C-terminal lability is not required for neuroserpin polymerisation in the endoplasmic reticulum, but the additional glycan facilitates degradation of the mutant protein during proteasomal impairment. In summary, our results indicate how normal and variant-specific N-linked glycosylation events relate to intracellular folding, misfolding, degradation and polymerisation of neuroserpin.
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Affiliation(s)
- Claudia Moriconi
- Department of Biology and Biotechnologies 'Charles Darwin', Sapienza University of Rome, Italy
| | - Adriana Ordoñez
- Department of Medicine, University of Cambridge, Cambridge Institute for Medical Research, UK
| | - Giuseppe Lupo
- Department of Chemistry, Sapienza University of Rome, Italy
| | - Bibek Gooptu
- Division of Asthma, Allergy and Lung Biology, King's College London, UK
| | - James A Irving
- Wolfson Institute for Biomedical Research, University College London, UK
| | - Rosina Noto
- National Research Council of Italy, Institute of Biophysics, Palermo, Italy
| | - Vincenzo Martorana
- National Research Council of Italy, Institute of Biophysics, Palermo, Italy
| | - Mauro Manno
- National Research Council of Italy, Institute of Biophysics, Palermo, Italy
| | - Valentina Timpano
- Department of Biology and Biotechnologies 'Charles Darwin', Sapienza University of Rome, Italy
| | - Noemi A Guadagno
- Department of Biology and Biotechnologies 'Charles Darwin', Sapienza University of Rome, Italy
| | - Lucy Dalton
- Department of Medicine, University of Cambridge, Cambridge Institute for Medical Research, UK
| | - Stefan J Marciniak
- Department of Medicine, University of Cambridge, Cambridge Institute for Medical Research, UK
| | - David A Lomas
- Wolfson Institute for Biomedical Research, University College London, UK
| | - Elena Miranda
- Department of Biology and Biotechnologies 'Charles Darwin', Sapienza University of Rome, Italy
- Pasteur Institute - Cenci Bolognetti Foundation, Sapienza University of Rome, Italy
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8
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Noto R, Randazzo L, Raccosta S, Caccia S, Moriconi C, Miranda E, Martorana V, Manno M. The stability and activity of human neuroserpin are modulated by a salt bridge that stabilises the reactive centre loop. Sci Rep 2015; 5:13666. [PMID: 26329378 PMCID: PMC4556959 DOI: 10.1038/srep13666] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2015] [Accepted: 08/03/2015] [Indexed: 11/26/2022] Open
Abstract
Neuroserpin (NS) is an inhibitory protein belonging to the serpin family and involved in several pathologies, including the dementia Familial Encephalopathy with Neuroserpin Inclusion Bodies (FENIB), a genetic neurodegenerative disease caused by accumulation of NS polymers. Our Molecular Dynamics simulations revealed the formation of a persistent salt bridge between Glu289 on strand s2C and Arg362 on the Reactive Centre Loop (RCL), a region important for the inhibitory activity of NS. Here, we validated this structural feature by simulating the Glu289Ala mutant, where the salt bridge is not present. Further, MD predictions were tested in vitro by purifying recombinant Glu289Ala NS from E. coli. The thermal and chemical stability along with the polymerisation propensity of both Wild Type and Glu289Ala NS were characterised by circular dichroism, emission spectroscopy and non-denaturant gel electrophoresis, respectively. The activity of both variants against the main target protease, tissue-type plasminogen activator (tPA), was assessed by SDS-PAGE and chromogenic kinetic assay. Our results showed that deletion of the salt bridge leads to a moderate but clear reduction of the overall protein stability and activity.
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Affiliation(s)
- Rosina Noto
- National Research Council of Italy, Institute of Biophysics, Palermo, Italy
| | - Loredana Randazzo
- National Research Council of Italy, Institute of Biophysics, Palermo, Italy
| | - Samuele Raccosta
- National Research Council of Italy, Institute of Biophysics, Palermo, Italy
| | - Sonia Caccia
- Department of Medical Biotechnologies and Translational Medicine, University of Milan, Milan, Italy
| | - Claudia Moriconi
- Department of Biology and Biotechnologies “Charles Darwin” and Pasteur Institute - Cenci Bolognetti Foundation, Sapienza University of Rome, Rome, Italy
| | - Elena Miranda
- Department of Biology and Biotechnologies “Charles Darwin” and Pasteur Institute - Cenci Bolognetti Foundation, Sapienza University of Rome, Rome, Italy
| | - Vincenzo Martorana
- National Research Council of Italy, Institute of Biophysics, Palermo, Italy
| | - Mauro Manno
- National Research Council of Italy, Institute of Biophysics, Palermo, Italy
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9
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Noto R, Santangelo MG, Levantino M, Cupane A, Mangione MR, Parisi D, Ricagno S, Bolognesi M, Manno M, Martorana V. Functional and dysfunctional conformers of human neuroserpin characterized by optical spectroscopies and Molecular Dynamics. BIOCHIMICA ET BIOPHYSICA ACTA 2015; 1854:110-7. [PMID: 25450507 PMCID: PMC4332418 DOI: 10.1016/j.bbapap.2014.10.002] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 06/13/2014] [Revised: 09/04/2014] [Accepted: 10/03/2014] [Indexed: 12/12/2022]
Abstract
Neuroserpin (NS) is a serine protease inhibitor (SERPIN) involved in different neurological pathologies, including the Familial Encephalopathy with Neuroserpin Inclusion Bodies (FENIB), related to the aberrant polymerization of NS mutants. Here we present an in vitro and in silico characterization of native neuroserpin and its dysfunctional conformation isoforms: the proteolytically cleaved conformer, the inactive latent conformer, and the polymeric species. Based on circular dichroism and fluorescence spectroscopy, we present an experimental validation of the latent model and highlight the main structural features of the different conformers. In particular, emission spectra of aromatic residues yield distinct conformational fingerprints, that provide a novel and simple spectroscopic tool for selecting serpin conformers in vitro. Based on the structural relationship between cleaved and latent serpins, we propose a structural model for latent NS, for which an experimental crystallographic structure is lacking. Molecular Dynamics simulations suggest that NS conformational stability and flexibility arise from a spatial distribution of intramolecular salt-bridges and hydrogen bonds.
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Affiliation(s)
- Rosina Noto
- Institute of Biophysics, National Research Council of Italy, Palermo, Italy
| | | | - Matteo Levantino
- Department of Physics and Chemistry, University of Palermo, Palermo, Italy
| | - Antonio Cupane
- Department of Physics and Chemistry, University of Palermo, Palermo, Italy
| | | | - Daniele Parisi
- Institute of Biophysics, National Research Council of Italy, Palermo, Italy; Department of Biosciences, Institute of Biophysics CNR, Italy and CIMAINA, University of Milano, Milan, Italy
| | - Stefano Ricagno
- Department of Biosciences, Institute of Biophysics CNR, Italy and CIMAINA, University of Milano, Milan, Italy
| | - Martino Bolognesi
- Department of Biosciences, Institute of Biophysics CNR, Italy and CIMAINA, University of Milano, Milan, Italy
| | - Mauro Manno
- Institute of Biophysics, National Research Council of Italy, Palermo, Italy.
| | - Vincenzo Martorana
- Institute of Biophysics, National Research Council of Italy, Palermo, Italy
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10
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Duvoix A, Roussel B, Lomas D. Molecular pathogenesis of alpha-1-antitrypsin deficiency. Rev Mal Respir 2014; 31:992-1002. [DOI: 10.1016/j.rmr.2014.03.015] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2012] [Accepted: 03/14/2014] [Indexed: 11/24/2022]
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11
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Schipanski A, Oberhauser F, Neumann M, Lange S, Szalay B, Krasemann S, van Leeuwen FW, Galliciotti G, Glatzel M. Lectin OS-9 delivers mutant neuroserpin to endoplasmic reticulum associated degradation in familial encephalopathy with neuroserpin inclusion bodies. Neurobiol Aging 2014; 35:2394-403. [PMID: 24795221 DOI: 10.1016/j.neurobiolaging.2014.04.002] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2013] [Revised: 03/20/2014] [Accepted: 04/01/2014] [Indexed: 12/11/2022]
Abstract
A feature of neurodegenerative diseases is the intraneuronal accumulation of misfolded proteins. In familial encephalopathy with neuroserpin inclusion bodies (FENIB), mutations in neuroserpin lead to accumulation of neuroserpin polymers within the endoplasmic reticulum (ER) of neurons. Cell culture based studies have shown that ER-associated degradation (ERAD) is involved in clearance of mutant neuroserpin. Here, we investigate how mutant neuroserpin is delivered to ERAD using cell culture and a murine model of FENIB. We show that the ER-lectin OS-9 but not XTP3-B is involved in ERAD of mutant neuroserpin. OS-9 binds mutant neuroserpin and the removal of glycosylation sites leads to increased neuroserpin protein load whereas overexpression of OS-9 decreases mutant neuroserpin. In FENIB mice, OS-9 but not XTP3-B is differently expressed and impairment of ERAD by partial inhibition of the ubiquitin proteasome system leads to increased neuroserpin protein load. These findings show that OS-9 delivers mutant neuroserpin to ERAD by recognition of glycan side chains and provide the first in vivo proof of involvement of ERAD in degradation of mutant neuroserpin.
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Affiliation(s)
- Angela Schipanski
- Institute of Neuropathology, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - Felix Oberhauser
- Institute of Neuropathology, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - Melanie Neumann
- Institute of Neuropathology, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - Sascha Lange
- Institute of Neuropathology, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - Beata Szalay
- Institute of Neuropathology, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - Susanne Krasemann
- Institute of Neuropathology, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - Fred W van Leeuwen
- Department of Neuroscience, Maastricht University, Maastricht, the Netherlands
| | - Giovanna Galliciotti
- Institute of Neuropathology, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - Markus Glatzel
- Institute of Neuropathology, University Medical Center Hamburg-Eppendorf, Hamburg, Germany.
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12
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Xin D, Holzenburg A, Burgess K. Small Molecule Probes That Perturb A Protein-protein Interface In Antithrombin. Chem Sci 2014; 5:4914-4921. [PMID: 25396040 DOI: 10.1039/c4sc01295j] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023] Open
Abstract
Small molecule probes for perturbing protein-protein interactions (PPIs) in vitro can be useful if they cause the target proteins to undergo biomedically relevant changes to their tertiary and quaternary structures. Application of the Exploring Key Orientations (EKO) strategy (J. Am. Chem. Soc., 2013, 135, 167 - 173) to a piperidinone-piperidine chemotype 1 indicated specific derivatives were candidates to perturb a protein-protein interface in the α-antithrombin dimer; those particular derivatives of 1 were prepared and tested. In the event, most of them significantly accelerated oligomerization of monomeric α-antithrombin, which is metastable in its oligomeric state. This assertion is supported by data from gel electrophoresis (non-denaturing PAGE; throughout) and probe-induced loss of α-antithrombin's inhibitor activity in a reaction catalyzed by thrombin. Kinetics of α-antithrombin oligomerization induced by the target compounds were examined. It was found that probes with O-benzyl-protected serine side-chains are the most active catalysts in the series, and reasons for this, based on modeling experiments, are proposed. Overall, this study reveals one of the first examples of small molecules designed to act at a protein-protein interface relevant to oligomerization of a serpin (ie α-antithrombin). The relevance of this to formation of oligomeric serpin fibrils, associated with the disease states known as "serpinopathies", is discussed.
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Affiliation(s)
- Dongyue Xin
- Department of Chemistry, Texas A & M University, Box 30012, College Station, TX 77842
| | - Andreas Holzenburg
- Microscopy and Imaging Center, Department of Biology, and Department of Biochemistry & Biophysics TAMU, College Station, TX 77843-2257
| | - Kevin Burgess
- Department of Chemistry, Texas A & M University, Box 30012, College Station, TX 77842
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13
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Martínez-Martínez I, Navarro-Fernández J, Aguila S, Miñano A, Bohdan N, De La Morena-Barrio ME, Ordóñez A, Martínez C, Vicente V, Corral J. The infective polymerization of conformationally unstable antithrombin mutants may play a role in the clinical severity of antithrombin deficiency. Mol Med 2012; 18:762-70. [PMID: 22481271 DOI: 10.2119/molmed.2012.00017] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2012] [Accepted: 03/29/2012] [Indexed: 11/06/2022] Open
Abstract
Mutations affecting mobile domains of antithrombin induce conformational instability resulting in protein polymerization that associates with a severe clinical phenotype, probably by an unknown gain of function. By homology with other conformational diseases, we speculated that these variants might infect wild-type (WT) monomers reducing the anticoagulant capacity. Infective polymerization of WT polymers and different P1 mutants (p.R425del, p.R425C and p.R425H) were evaluated by using native gels and radiolabeled WT monomers and functional assays. Human embryonic kidney cells expressing the Epstein-Barr nuclear antigen 1 (HEK-EBNA) cells expressing inducible (p.R425del) or two novel constitutive (p.F271S and p.M370T) conformational variants were used to evaluate intracellular and secreted antithrombin under mild stress (pH 6.5 and 39°C for 5 h). We demonstrated the conformational sensitivity of antithrombin London (p.R425del) to form polymers under mild heating. Under these conditions purified antithrombin London recruited WT monomers into growing polymers, reducing the anticoagulant activity. This process was also observed in the plasma of patients with p.R425del, p.R425C and p.R425H mutations. Under moderate stress, coexpression of WT and conformational variants in HEK-EBNA cells increased the intracellular retention of antithrombin and the formation of disulfide-linked polymers, which correlated with impaired secretion and reduction of anticoagulant activity in the medium. Therefore, mutations inducing conformational instability in antithrombin allow its polymerization with the subsequent loss of function, which under stress could sequestrate WT monomers, resulting in a new prothrombotic gain of function, particularly relevant for intracellular antithrombin. The in vitro results suggest a temporal and severe plasma antithrombin deficiency that may contribute to the development of the thrombotic event and to the clinical severity of these mutations.
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Affiliation(s)
- Irene Martínez-Martínez
- Department of Internal Medicine, Centro Regional de Hemodonación, University of Murcia, Murcia, Spain
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14
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Topping TB, Gloss LM. The impact of solubility and electrostatics on fibril formation by the H3 and H4 histones. Protein Sci 2011; 20:2060-73. [PMID: 21953551 DOI: 10.1002/pro.743] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2011] [Revised: 09/01/2011] [Accepted: 09/08/2011] [Indexed: 12/15/2022]
Abstract
The goal of this study was to examine fibril formation by the heterodimeric eukaryotic histones (H2A-H2B and H3-H4) and homodimeric archaeal histones (hMfB and hPyA1). The histone fold dimerization motif is an obligatorily domain-swapped structure comprised of two fused helix:β-loop:helix motifs. Domain swapping has been proposed as a mechanism for the evolution of protein oligomers as well as a means to form precursors in the formation of amyloid-like fibrils. Despite sharing a common fold, the eukaryotic histones of the core nucleosome and archaeal histones fold by kinetic mechanisms of differing complexity with transient population of partially folded monomeric and/or dimeric species. No relationship was apparent between fibrillation propensity and equilibrium stability or population of kinetic intermediates. Only H3 and H4, as isolated monomers and as a heterodimer, readily formed fibrils at room temperature, and this propensity correlates with the significantly lower solubility of these polypeptides. The fibrils were characterized by ThT fluorescence, FTIR, and far-UV CD spectroscopies and electron microscopy. The helical histone fold comprises the protease-resistant core of the fibrils, with little or no protease protection of the poorly structured N-terminal tails. The highly charged tails inhibit fibrillation through electrostatic repulsion. Kinetic studies indicate that H3 and H4 form a co-fibril, with simultaneous incorporation of both histones. The potential impact of H3 and H4 fibrillation on the cytotoxicity of extracellular histones and α-synuclein-mediated neurotoxicity and fibrillation is considered.
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Affiliation(s)
- Traci B Topping
- School of Molecular Biosciences, Washington State University, Pullman, Washington 99164-7520, USA
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15
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Abstract
Serpins have been studied as a distinct protein superfamily since the early 80s. In spite of the poor sequence homology between family members, serpins share a highly conserved core structure that is critical for their functioning as serine protease inhibitors. Therefore, discoveries made about one serpin can be related to the others. In this short review, I introduce the serpin structure and general mechanism of protease inhibition, and illustrate, using recent crystallographic and biochemical data on antithrombin (AT), how serpin activity can be modulated by cofactors. The ability of the serpins to undergo conformational change is critical for their function, but it also renders them uniquely susceptible to mutations that perturb their folding, leading to deficiency and disease. A recent crystal structure of an AT dimer revealed that serpins can participate in large-scale domain-swaps to form stable polymers, and that such a mechanism may explain the accumulation of misfolded serpins within secretory cells. Serpins play important roles in haemostasis and fibrinolysis, and although each will have some elements specifically tailored for its individual function, the mechanisms described here provide a general conceptual framework.
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Affiliation(s)
- J A Huntington
- Department of Haematology, Cambridge Institute for Medical Research, University of Cambridge, Cambridge, UK.
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Roussel BD, Irving JA, Ekeowa UI, Belorgey D, Haq I, Ordóñez A, Kruppa AJ, Duvoix A, Rashid ST, Crowther DC, Marciniak SJ, Lomas DA. Unravelling the twists and turns of the serpinopathies. FEBS J 2011; 278:3859-67. [DOI: 10.1111/j.1742-4658.2011.08201.x] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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17
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Irving JA, Ekeowa UI, Belorgey D, Haq I, Gooptu B, Miranda E, Pérez J, Roussel BD, Ordóñez A, Dalton LE, Thomas SE, Marciniak SJ, Parfrey H, Chilvers ER, Teckman JH, Alam S, Mahadeva R, Rashid ST, Vallier L, Lomas DA. The serpinopathies studying serpin polymerization in vivo. Methods Enzymol 2011; 501:421-66. [PMID: 22078544 DOI: 10.1016/b978-0-12-385950-1.00018-3] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
The serpinopathies result from point mutations in members of the serine protease inhibitor or serpin superfamily. They are characterized by the formation of ordered polymers that are retained within the cell of synthesis. This causes disease by a "toxic gain of function" from the accumulated protein and a "loss of function" as a result of the deficiency of inhibitors that control important proteolytic cascades. The serpinopathies are exemplified by the Z (Glu342Lys) mutant of α₁-antitrypsin that results in the retention of ordered polymers within the endoplasmic reticulum of hepatocytes. These polymers form the intracellular inclusions that are associated with neonatal hepatitis, cirrhosis, and hepatocellular carcinoma. A second example results from mutations in the neurone-specific serpin-neuroserpin to form ordered polymers that are retained as inclusions within subcortical neurones as Collins' bodies. These inclusions underlie the autosomal dominant dementia familial encephalopathy with neuroserpin inclusion bodies or FENIB. There are different pathways to polymer formation in vitro but not all form polymers that are relevant in vivo. It is therefore essential that protein-based structural studies are interpreted in the context of human samples and cell and animal models of disease. We describe here the biochemical techniques, monoclonal antibodies, cell biology, animal models, and stem cell technology that are useful to characterize the serpin polymers that form in vivo.
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Affiliation(s)
- James A Irving
- Department of Medicine, Cambridge Institute for Medical Research, University of Cambridge, Cambridge, United Kingdom
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18
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19
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Tanaka N, Morimoto Y, Noguchi Y, Tada T, Waku T, Kunugi S, Morii T, Lee YF, Konno T, Takahashi N. The mechanism of fibril formation of a non-inhibitory serpin ovalbumin revealed by the identification of amyloidogenic core regions. J Biol Chem 2010; 286:5884-94. [PMID: 21156792 DOI: 10.1074/jbc.m110.176396] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Ovalbumin (OVA), a non-inhibitory member of the serpin superfamily, forms fibrillar aggregates upon heat-induced denaturation. Recent studies suggested that OVA fibrils are generated by a mechanism similar to that of amyloid fibril formation, which is distinct from polymerization mechanisms proposed for other serpins. In this study, we provide new insights into the mechanism of OVA fibril formation through identification of amyloidogenic core regions using synthetic peptide fragments, site-directed mutagenesis, and limited proteolysis. OVA possesses a single disulfide bond between Cys(73) and Cys(120) in the N-terminal helical region of the protein. Heat treatment of disulfide-reduced OVA resulted in the formation of long straight fibrils that are distinct from the semiflexible fibrils formed from OVA with an intact disulfide. Computer predictions suggest that helix B (hB) of the N-terminal region, strand 3A, and strands 4-5B are highly β-aggregation-prone regions. These predictions were confirmed by the fact that synthetic peptides corresponding to these regions formed amyloid fibrils. Site-directed mutagenesis of OVA indicated that V41A substitution in hB interfered with the formation of fibrils. Co-incubation of a soluble peptide fragment of hB with the disulfide-intact full-length OVA consistently promoted formation of long straight fibrils. In addition, the N-terminal helical region of the heat-induced fibril of OVA was protected from limited proteolysis. These results indicate that the heat-induced fibril formation of OVA occurs by a mechanism involving transformation of the N-terminal helical region of the protein to β-strands, thereby forming sequential intermolecular linkages.
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Affiliation(s)
- Naoki Tanaka
- Department of Biomolecular Engineering, Kyoto Institute of Technology, Matsugasaki, Sakyo, Kyoto 606-8585, Japan.
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Belorgey D, Irving JA, Ekeowa UI, Freeke J, Roussel BD, Miranda E, Pérez J, Robinson CV, Marciniak SJ, Crowther DC, Michel CH, Lomas DA. Characterisation of serpin polymers in vitro and in vivo. Methods 2010; 53:255-66. [PMID: 21115126 DOI: 10.1016/j.ymeth.2010.11.008] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2010] [Accepted: 11/21/2010] [Indexed: 10/18/2022] Open
Abstract
Neuroserpin is a member of the serine protease inhibitor or serpin superfamily of proteins. It is secreted by neurones and plays an important role in the regulation of tissue plasminogen activator at the synapse. Point mutations in the neuroserpin gene cause the autosomal dominant dementia familial encephalopathy with neuroserpin inclusion bodies or FENIB. This is one of a group of disorders caused by mutations in the serpins that are collectively known as the serpinopathies. Others include α(1)-antitrypsin deficiency and deficiency of C1 inhibitor, antithrombin and α(1)-antichymotrypsin. The serpinopathies are characterised by delays in protein folding and the retention of ordered polymers of the mutant serpin within the cell of synthesis. The clinical phenotype results from either a toxic gain of function from the inclusions or a loss of function, as there is insufficient protease inhibitor to regulate important proteolytic cascades. We describe here the methods required to characterise the polymerisation of neuroserpin and draw parallels with the polymerisation of α(1)-antitrypsin. It is important to recognise that the conditions in which experiments are performed will have a major effect on the findings. For example, incubation of monomeric serpins with guanidine or urea will produce polymers that are not found in vivo. The characterisation of the pathological polymers requires heating of the folded protein or alternatively the assessment of ordered polymers from cell and animal models of disease or from the tissues of humans who carry the mutation.
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Affiliation(s)
- Didier Belorgey
- Dept. of Medicine, University of Cambridge, Cambridge Institute for Medical Research, Wellcome Trust/MRC Building, Hills Road, Cambridge CB2 0XY, UK
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