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Kim SJ, Song J, Reading NS, Lautersztain J, Kutlar A, Agarwal AM, Coetzer TL, Prchal JT. Novel mechanism of hereditary pyropoikilocytosis phenotype due to co-inheritance of β globin and α spectrin mutations. Am J Hematol 2021; 96:E150-E154. [PMID: 33556202 DOI: 10.1002/ajh.26121] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2021] [Revised: 02/02/2021] [Accepted: 02/03/2021] [Indexed: 11/10/2022]
Affiliation(s)
- Soo Jin Kim
- Hematology University of Utah & Huntsman Cancer Center Salt Lake City Utah
| | - Jihyun Song
- Hematology University of Utah & Huntsman Cancer Center Salt Lake City Utah
| | | | | | | | | | - Theresa L. Coetzer
- Department of Molecular Medicine and Haematology, School of Pathology University of the Witwatersrand Johannesburg South Africa
| | - Josef T. Prchal
- Hematology University of Utah & Huntsman Cancer Center Salt Lake City Utah
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2
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Le Manach C, Dam J, Woodland JG, Kaur G, Khonde LP, Brunschwig C, Njoroge M, Wicht KJ, Horatscheck A, Paquet T, Boyle GA, Gibhard L, Taylor D, Lawrence N, Yeo T, Mok S, Eastman RT, Dorjsuren D, Talley DC, Guo H, Simeonov A, Reader J, van der Watt M, Erlank E, Venter N, Zawada JW, Aswat A, Nardini L, Coetzer TL, Lauterbach SB, Bezuidenhout BC, Theron A, Mancama D, Koekemoer LL, Birkholtz LM, Wittlin S, Delves M, Ottilie S, Winzeler EA, von Geldern TW, Smith D, Fidock DA, Street LJ, Basarab GS, Duffy J, Chibale K. Identification and Profiling of a Novel Diazaspiro[3.4]octane Chemical Series Active against Multiple Stages of the Human Malaria Parasite Plasmodium falciparum and Optimization Efforts. J Med Chem 2021; 64:2291-2309. [PMID: 33573376 DOI: 10.1021/acs.jmedchem.1c00034] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
A novel diazaspiro[3.4]octane series was identified from a Plasmodium falciparum whole-cell high-throughput screening campaign. Hits displayed activity against multiple stages of the parasite lifecycle, which together with a novel sp3-rich scaffold provided an attractive starting point for a hit-to-lead medicinal chemistry optimization and biological profiling program. Structure-activity-relationship studies led to the identification of compounds that showed low nanomolar asexual blood-stage activity (<50 nM) together with strong gametocyte sterilizing properties that translated to transmission-blocking activity in the standard membrane feeding assay. Mechanistic studies through resistance selection with one of the analogues followed by whole-genome sequencing implicated the P. falciparum cyclic amine resistance locus in the mode of resistance.
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Affiliation(s)
- Claire Le Manach
- Drug Discovery and Development Center (H3D), University of Cape Town, Rondebosch 7701, South Africa
| | - Jean Dam
- Drug Discovery and Development Center (H3D), University of Cape Town, Rondebosch 7701, South Africa
| | - John G Woodland
- Drug Discovery and Development Center (H3D), University of Cape Town, Rondebosch 7701, South Africa
| | - Gurminder Kaur
- Drug Discovery and Development Center (H3D), University of Cape Town, Rondebosch 7701, South Africa
| | - Lutete P Khonde
- Drug Discovery and Development Center (H3D), University of Cape Town, Rondebosch 7701, South Africa
| | - Christel Brunschwig
- Drug Discovery and Development Center (H3D), Division of Clinical Pharmacology, Department of Medicine, University of Cape Town, Observatory 7925, South Africa
| | - Mathew Njoroge
- Drug Discovery and Development Center (H3D), Division of Clinical Pharmacology, Department of Medicine, University of Cape Town, Observatory 7925, South Africa
| | - Kathryn J Wicht
- Department of Microbiology and Immunology, Columbia University Irving Medical Center, New York, New York 10032, United States
| | - André Horatscheck
- Drug Discovery and Development Center (H3D), University of Cape Town, Rondebosch 7701, South Africa
| | - Tanya Paquet
- Drug Discovery and Development Center (H3D), University of Cape Town, Rondebosch 7701, South Africa
| | - Grant A Boyle
- Drug Discovery and Development Center (H3D), University of Cape Town, Rondebosch 7701, South Africa
| | - Liezl Gibhard
- Drug Discovery and Development Center (H3D), Division of Clinical Pharmacology, Department of Medicine, University of Cape Town, Observatory 7925, South Africa
| | - Dale Taylor
- Drug Discovery and Development Center (H3D), Division of Clinical Pharmacology, Department of Medicine, University of Cape Town, Observatory 7925, South Africa
| | - Nina Lawrence
- Drug Discovery and Development Center (H3D), Division of Clinical Pharmacology, Department of Medicine, University of Cape Town, Observatory 7925, South Africa
| | - Tomas Yeo
- Department of Microbiology and Immunology, Columbia University Irving Medical Center, New York, New York 10032, United States
| | - Sachel Mok
- Department of Microbiology and Immunology, Columbia University Irving Medical Center, New York, New York 10032, United States
| | - Richard T Eastman
- Division of Preclinical Innovation, National Center for Advancing Translational Sciences, National Institutes of Health, Bethesda, Maryland 20892, United States
| | - Dorjbal Dorjsuren
- Division of Preclinical Innovation, National Center for Advancing Translational Sciences, National Institutes of Health, Bethesda, Maryland 20892, United States
| | - Daniel C Talley
- Division of Preclinical Innovation, National Center for Advancing Translational Sciences, National Institutes of Health, Bethesda, Maryland 20892, United States
| | - Hui Guo
- Division of Preclinical Innovation, National Center for Advancing Translational Sciences, National Institutes of Health, Bethesda, Maryland 20892, United States
| | - Anton Simeonov
- Division of Preclinical Innovation, National Center for Advancing Translational Sciences, National Institutes of Health, Bethesda, Maryland 20892, United States
| | - Janette Reader
- Department of Biochemistry, Genetics and Microbiology, Institute for Sustainable Malaria Control, University of Pretoria, Hatfield, Pretoria 0028, South Africa
| | - Mariëtte van der Watt
- Department of Biochemistry, Genetics and Microbiology, Institute for Sustainable Malaria Control, University of Pretoria, Hatfield, Pretoria 0028, South Africa
| | - Erica Erlank
- Wits Research Institute for Malaria, School of Pathology, Faculty of Health Sciences, University of the Witwatersrand, Johannesburg 2193, South Africa.,Centre for Emerging Zoonotic and Parasitic Diseases, National Institute for Communicable Diseases of the National Health Laboratory Service, Johannesburg 2192, South Africa
| | - Nelius Venter
- Wits Research Institute for Malaria, School of Pathology, Faculty of Health Sciences, University of the Witwatersrand, Johannesburg 2193, South Africa.,Centre for Emerging Zoonotic and Parasitic Diseases, National Institute for Communicable Diseases of the National Health Laboratory Service, Johannesburg 2192, South Africa
| | - Jacek W Zawada
- Wits Research Institute for Malaria, School of Pathology, Faculty of Health Sciences, University of the Witwatersrand, Johannesburg 2193, South Africa.,Centre for Emerging Zoonotic and Parasitic Diseases, National Institute for Communicable Diseases of the National Health Laboratory Service, Johannesburg 2192, South Africa
| | - Ayesha Aswat
- Wits Research Institute for Malaria, School of Pathology, Faculty of Health Sciences, University of the Witwatersrand, Johannesburg 2193, South Africa.,Centre for Emerging Zoonotic and Parasitic Diseases, National Institute for Communicable Diseases of the National Health Laboratory Service, Johannesburg 2192, South Africa
| | - Luisa Nardini
- Wits Research Institute for Malaria, School of Pathology, Faculty of Health Sciences, University of the Witwatersrand, Johannesburg 2193, South Africa.,Centre for Emerging Zoonotic and Parasitic Diseases, National Institute for Communicable Diseases of the National Health Laboratory Service, Johannesburg 2192, South Africa
| | - Theresa L Coetzer
- Wits Research Institute for Malaria, School of Pathology, Department of Molecular Medicine and Haematology, Faculty of Health Sciences, University of the Witwatersrand, Johannesburg 2193, South Africa
| | - Sonja B Lauterbach
- Wits Research Institute for Malaria, School of Pathology, Department of Molecular Medicine and Haematology, Faculty of Health Sciences, University of the Witwatersrand, Johannesburg 2193, South Africa
| | - Belinda C Bezuidenhout
- Wits Research Institute for Malaria, School of Pathology, Department of Molecular Medicine and Haematology, Faculty of Health Sciences, University of the Witwatersrand, Johannesburg 2193, South Africa
| | - Anjo Theron
- Biosciences, Council for Scientific and Industrial Research, P.O. Box 395, Pretoria 0001, South Africa
| | - Dalu Mancama
- Biosciences, Council for Scientific and Industrial Research, P.O. Box 395, Pretoria 0001, South Africa
| | - Lizette L Koekemoer
- Wits Research Institute for Malaria, School of Pathology, Faculty of Health Sciences, University of the Witwatersrand, Johannesburg 2193, South Africa.,Centre for Emerging Zoonotic and Parasitic Diseases, National Institute for Communicable Diseases of the National Health Laboratory Service, Johannesburg 2192, South Africa
| | - Lyn-Marie Birkholtz
- Department of Biochemistry, Genetics and Microbiology, Institute for Sustainable Malaria Control, University of Pretoria, Hatfield, Pretoria 0028, South Africa
| | - Sergio Wittlin
- Swiss Tropical and Public Health Institute, Socinstrasse 57, 4002 Basel, Switzerland.,University of Basel, 4003 Basel, Switzerland
| | - Michael Delves
- Imperial College London, South Kensington, London SW7 2AZ, U.K.,London School of Hygiene and Tropical Medicine, London WC1E 7HT, U.K
| | - Sabine Ottilie
- Division of Host-Microbe Systems & Therapeutics, Department of Pediatrics, University of California San Diego, La Jolla, California 92093-076, United States
| | - Elizabeth A Winzeler
- Division of Host-Microbe Systems & Therapeutics, Department of Pediatrics, University of California San Diego, La Jolla, California 92093-076, United States
| | | | | | - David A Fidock
- Department of Microbiology and Immunology, Columbia University Irving Medical Center, New York, New York 10032, United States.,Division of Infectious Diseases, Department of Medicine, Columbia University Irving Medical Center, New York, New York 10032, United States
| | - Leslie J Street
- Drug Discovery and Development Center (H3D), University of Cape Town, Rondebosch 7701, South Africa
| | - Gregory S Basarab
- Drug Discovery and Development Center (H3D), University of Cape Town, Rondebosch 7701, South Africa
| | - James Duffy
- Medicines for Malaria Venture, ICC, Route de Pré-Bois 20, P.O. Box 1826, 1215 Geneva, Switzerland
| | - Kelly Chibale
- Drug Discovery and Development Center (H3D), University of Cape Town, Rondebosch 7701, South Africa.,South African Medical Research Council, Drug Discovery and Development Research Unit, Department of Chemistry and Institute of Infectious Disease and Molecular Medicine, University of Cape Town, Rondebosch 7701, South Africa
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3
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van der Watt ME, Reader J, Churchyard A, Nondaba SH, Lauterbach SB, Niemand J, Abayomi S, van Biljon RA, Connacher JI, van Wyk RDJ, Le Manach C, Paquet T, González Cabrera D, Brunschwig C, Theron A, Lozano-Arias S, Rodrigues JFI, Herreros E, Leroy D, Duffy J, Street LJ, Chibale K, Mancama D, Coetzer TL, Birkholtz LM. Potent Plasmodium falciparum gametocytocidal compounds identified by exploring the kinase inhibitor chemical space for dual active antimalarials. J Antimicrob Chemother 2019; 73:1279-1290. [PMID: 29420756 DOI: 10.1093/jac/dky008] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2017] [Accepted: 01/02/2018] [Indexed: 01/06/2023] Open
Abstract
Objectives Novel chemical tools to eliminate malaria should ideally target both the asexual parasites and transmissible gametocytes. Several imidazopyridazines (IMPs) and 2-aminopyridines (2-APs) have been described as potent antimalarial candidates targeting lipid kinases. However, these have not been extensively explored for stage-specific inhibition of gametocytes in Plasmodium falciparum parasites. Here we provide an in-depth evaluation of the gametocytocidal activity of compounds from these chemotypes and identify novel starting points for dual-acting antimalarials. Methods We evaluated compounds against P. falciparum gametocytes using several assay platforms for cross-validation and stringently identified hits that were further profiled for stage specificity, speed of action and ex vivo efficacy. Physicochemical feature extraction and chemogenomic fingerprinting were applied to explore the kinase inhibition susceptibility profile. Results We identified 34 compounds with submicromolar activity against late stage gametocytes, validated across several assay platforms. Of these, 12 were potent at <100 nM (8 were IMPs and 4 were 2-APs) and were also active against early stage gametocytes and asexual parasites, with >1000-fold selectivity towards the parasite over mammalian cells. Front-runner compounds targeted mature gametocytes within 48 h and blocked transmission to mosquitoes. The resultant chemogenomic fingerprint of parasites treated with the lead compounds revealed the importance of targeting kinases in asexual parasites and gametocytes. Conclusions This study encompasses an in-depth evaluation of the kinase inhibitor space for gametocytocidal activity. Potent lead compounds have enticing dual activities and highlight the importance of targeting the kinase superfamily in malaria elimination strategies.
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Affiliation(s)
- Mariëtte E van der Watt
- Department of Biochemistry, Institute for Sustainable Malaria Control and South African Medical Research Council Collaborating Centre for Malaria Research, University of Pretoria, Private Bag x20, Hatfield, Pretoria 0028, South Africa
| | - Janette Reader
- Department of Biochemistry, Institute for Sustainable Malaria Control and South African Medical Research Council Collaborating Centre for Malaria Research, University of Pretoria, Private Bag x20, Hatfield, Pretoria 0028, South Africa
| | - Alisje Churchyard
- Plasmodium Molecular Research Unit, Wits Research Institute for Malaria, Department of Molecular Medicine and Haematology, School of Pathology, Faculty of Health Sciences, University of the Witwatersrand and National Health Laboratory Service, Johannesburg 2193, South Africa
| | - Sindisiwe H Nondaba
- Department of Biochemistry, Institute for Sustainable Malaria Control and South African Medical Research Council Collaborating Centre for Malaria Research, University of Pretoria, Private Bag x20, Hatfield, Pretoria 0028, South Africa
| | - Sonja B Lauterbach
- Plasmodium Molecular Research Unit, Wits Research Institute for Malaria, Department of Molecular Medicine and Haematology, School of Pathology, Faculty of Health Sciences, University of the Witwatersrand and National Health Laboratory Service, Johannesburg 2193, South Africa
| | - Jandeli Niemand
- Department of Biochemistry, Institute for Sustainable Malaria Control and South African Medical Research Council Collaborating Centre for Malaria Research, University of Pretoria, Private Bag x20, Hatfield, Pretoria 0028, South Africa
| | - Sijuade Abayomi
- Department of Biochemistry, Institute for Sustainable Malaria Control and South African Medical Research Council Collaborating Centre for Malaria Research, University of Pretoria, Private Bag x20, Hatfield, Pretoria 0028, South Africa
| | - Riëtte A van Biljon
- Department of Biochemistry, Institute for Sustainable Malaria Control and South African Medical Research Council Collaborating Centre for Malaria Research, University of Pretoria, Private Bag x20, Hatfield, Pretoria 0028, South Africa
| | - Jessica I Connacher
- Department of Biochemistry, Institute for Sustainable Malaria Control and South African Medical Research Council Collaborating Centre for Malaria Research, University of Pretoria, Private Bag x20, Hatfield, Pretoria 0028, South Africa
| | - Roelof D J van Wyk
- Department of Biochemistry, Institute for Sustainable Malaria Control and South African Medical Research Council Collaborating Centre for Malaria Research, University of Pretoria, Private Bag x20, Hatfield, Pretoria 0028, South Africa
| | - Claire Le Manach
- Drug Discovery and Development Centre (H3D), Department of Chemistry, University of Cape Town, Rondebosch 7701, South Africa
| | - Tanya Paquet
- Drug Discovery and Development Centre (H3D), Department of Chemistry, University of Cape Town, Rondebosch 7701, South Africa
| | - Diego González Cabrera
- Drug Discovery and Development Centre (H3D), Department of Chemistry, University of Cape Town, Rondebosch 7701, South Africa
| | - Christel Brunschwig
- Drug Discovery and Development Centre (H3D), Department of Chemistry, University of Cape Town, Rondebosch 7701, South Africa
| | - Anjo Theron
- Biosciences, Council for Scientific and Industrial Research, PO Box 395, Pretoria 0001, South Africa
| | - Sonia Lozano-Arias
- GlaxoSmithKline, Tres Cantos Medicines Development Campus, Severo Ochoa, 2, 28760 Tres Cantos, Madrid, Spain
| | - Janneth F I Rodrigues
- GlaxoSmithKline, Tres Cantos Medicines Development Campus, Severo Ochoa, 2, 28760 Tres Cantos, Madrid, Spain
| | - Esperanza Herreros
- GlaxoSmithKline, Tres Cantos Medicines Development Campus, Severo Ochoa, 2, 28760 Tres Cantos, Madrid, Spain
| | - Didier Leroy
- Medicines for Malaria Venture, International Center Cointrin, Route de Pré-Bois 20, 1215, Geneva, Switzerland
| | - James Duffy
- Medicines for Malaria Venture, International Center Cointrin, Route de Pré-Bois 20, 1215, Geneva, Switzerland
| | - Leslie J Street
- Drug Discovery and Development Centre (H3D), Department of Chemistry, University of Cape Town, Rondebosch 7701, South Africa
| | - Kelly Chibale
- Drug Discovery and Development Centre (H3D), Department of Chemistry, University of Cape Town, Rondebosch 7701, South Africa.,South African Medical Research Council, Drug Discovery and Development Research Unit, Department of Chemistry and Institute of Infectious Disease and Molecular Medicine, University of Cape Town, Rondebosch 7701, South Africa
| | - Dalu Mancama
- Biosciences, Council for Scientific and Industrial Research, PO Box 395, Pretoria 0001, South Africa
| | - Theresa L Coetzer
- Plasmodium Molecular Research Unit, Wits Research Institute for Malaria, Department of Molecular Medicine and Haematology, School of Pathology, Faculty of Health Sciences, University of the Witwatersrand and National Health Laboratory Service, Johannesburg 2193, South Africa
| | - Lyn-Marie Birkholtz
- Department of Biochemistry, Institute for Sustainable Malaria Control and South African Medical Research Council Collaborating Centre for Malaria Research, University of Pretoria, Private Bag x20, Hatfield, Pretoria 0028, South Africa
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4
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Kumar M, Okombo J, Mambwe D, Taylor D, Lawrence N, Reader J, van der Watt M, Fontinha D, Sanches-Vaz M, Bezuidenhout BC, Lauterbach SB, Liebenberg D, Birkholtz LM, Coetzer TL, Prudêncio M, Egan TJ, Wittlin S, Chibale K. Multistage Antiplasmodium Activity of Astemizole Analogues and Inhibition of Hemozoin Formation as a Contributor to Their Mode of Action. ACS Infect Dis 2019; 5:303-315. [PMID: 30525439 DOI: 10.1021/acsinfecdis.8b00272] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
A drug repositioning approach was leveraged to derivatize astemizole (AST), an antihistamine drug whose antimalarial activity was previously identified in a high-throughput screen. The multistage activity potential against the Plasmodium parasite's life cycle of the subsequent analogues was examined by evaluating against the parasite asexual blood, liver, and sexual gametocytic stages. In addition, the previously reported contribution of heme detoxification to the compound's mode of action was interrogated. Ten of the 17 derivatives showed half-maximal inhibitory concentrations (IC50s) of <0.1 μM against the chloroquine (CQ)-sensitive Plasmodium falciparum NF54 ( PfNF54) strain while maintaining submicromolar potency against the multidrug-resistant strain, PfK1, with most showing low likelihood of cross-resistance with CQ. Selected analogues ( PfNF54-IC50 < 0.1 μM) were tested for cytotoxicity on Chinese hamster ovarian (CHO) cells and found to be highly selective (selectivity index > 100). Screening of AST and its analogues against gametocytes revealed their moderate activity (IC50: 1-5 μM) against late stage P. falciparum gametocytes, while the evaluation of activity against P. berghei liver stages identified one compound (3) with 3-fold greater activity than the parent AST compound. Mechanistic studies showed a strong correlation between in vitro inhibition of β-hematin formation by the AST derivatives and their antiplasmodium IC50s. Analyses of intracellular inhibition of hemozoin formation within the parasite further yielded signatures attributable to a possible perturbation of the heme detoxification machinery.
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Affiliation(s)
- Malkeet Kumar
- Department of Chemistry, University of Cape Town, Rondebosch 7701, South Africa
| | - John Okombo
- Department of Chemistry, University of Cape Town, Rondebosch 7701, South Africa
| | - Dickson Mambwe
- Department of Chemistry, University of Cape Town, Rondebosch 7701, South Africa
| | - Dale Taylor
- Drug Discovery and Development Centre (H3D), Division of Clinical Pharmacology, Department of Medicine, University of Cape Town, Observatory 7925, South Africa
| | - Nina Lawrence
- Drug Discovery and Development Centre (H3D), Division of Clinical Pharmacology, Department of Medicine, University of Cape Town, Observatory 7925, South Africa
| | - Janette Reader
- Department of Biochemistry, Genetics and Microbiology, Institute for Sustainable Malaria Control, University of Pretoria, Private Bag X20, Hatfield 0028, South Africa
| | - Mariëtte van der Watt
- Department of Biochemistry, Genetics and Microbiology, Institute for Sustainable Malaria Control, University of Pretoria, Private Bag X20, Hatfield 0028, South Africa
| | - Diana Fontinha
- Instituto de Medicina Molecular, Faculdade de Medicina, Universidade de Lisboa, Av. Prof. Egas Moniz, 1649-028 Lisboa, Portugal
| | - Margarida Sanches-Vaz
- Instituto de Medicina Molecular, Faculdade de Medicina, Universidade de Lisboa, Av. Prof. Egas Moniz, 1649-028 Lisboa, Portugal
| | - Belinda C. Bezuidenhout
- Department of Molecular Medicine and Haematology, School of Pathology, Faculty of Health Sciences, University of the Witwatersrand and National Health Laboratory Service, Johannesburg 2193, South Africa
| | - Sonja B. Lauterbach
- Department of Molecular Medicine and Haematology, School of Pathology, Faculty of Health Sciences, University of the Witwatersrand and National Health Laboratory Service, Johannesburg 2193, South Africa
| | - Dale Liebenberg
- Department of Molecular Medicine and Haematology, School of Pathology, Faculty of Health Sciences, University of the Witwatersrand and National Health Laboratory Service, Johannesburg 2193, South Africa
| | - Lyn-Marie Birkholtz
- Department of Biochemistry, Genetics and Microbiology, Institute for Sustainable Malaria Control, University of Pretoria, Private Bag X20, Hatfield 0028, South Africa
| | - Theresa L. Coetzer
- Department of Molecular Medicine and Haematology, School of Pathology, Faculty of Health Sciences, University of the Witwatersrand and National Health Laboratory Service, Johannesburg 2193, South Africa
| | - Miguel Prudêncio
- Instituto de Medicina Molecular, Faculdade de Medicina, Universidade de Lisboa, Av. Prof. Egas Moniz, 1649-028 Lisboa, Portugal
| | - Timothy J. Egan
- Department of Chemistry, University of Cape Town, Rondebosch 7701, South Africa
- Institute of Infectious Disease and Molecular Medicine, University of Cape Town, Rondebosch 7701, South Africa
| | - Sergio Wittlin
- Swiss Tropical and Public Health Institute, Socinstrasse 57, 4002 Basel, Switzerland
- University of Basel, 4003 Basel, Switzerland
| | - Kelly Chibale
- Department of Chemistry, University of Cape Town, Rondebosch 7701, South Africa
- Institute of Infectious Disease and Molecular Medicine, University of Cape Town, Rondebosch 7701, South Africa
- South African Medical Research Council Drug Discovery and Development Research Unit, Department of Chemistry, University of Cape Town, Rondebosch 7701, South Africa
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5
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Mayoka G, Njoroge M, Okombo J, Gibhard L, Sanches-Vaz M, Fontinha D, Birkholtz LM, Reader J, van der Watt M, Coetzer TL, Lauterbach S, Churchyard A, Bezuidenhout B, Egan TJ, Yeates C, Wittlin S, Prudêncio M, Chibale K. Structure–Activity Relationship Studies and Plasmodium Life Cycle Profiling Identifies Pan-Active N-Aryl-3-trifluoromethyl Pyrido[1,2-a]benzimidazoles Which Are Efficacious in an in Vivo Mouse Model of Malaria. J Med Chem 2018; 62:1022-1035. [DOI: 10.1021/acs.jmedchem.8b01769] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Affiliation(s)
- Godfrey Mayoka
- Department of Chemistry, University of Cape Town, Rondebosch 7701, South Africa
| | - Mathew Njoroge
- Drug Discovery and Development Centre (H3D), Division of Clinical Pharmacology, Department of Medicine, University of Cape Town, Observatory, Cape Town 7925, South Africa
| | - John Okombo
- Department of Chemistry, University of Cape Town, Rondebosch 7701, South Africa
| | - Liezl Gibhard
- Drug Discovery and Development Centre (H3D), Division of Clinical Pharmacology, Department of Medicine, University of Cape Town, Observatory, Cape Town 7925, South Africa
| | - Margarida Sanches-Vaz
- Instituto de Medicina Molecular João Lobo Antunes, Faculdade de Medicina, Universidade de Lisboa, Av. Prof. Egas Moniz, 1649-028 Lisbon, Portugal
| | - Diana Fontinha
- Instituto de Medicina Molecular João Lobo Antunes, Faculdade de Medicina, Universidade de Lisboa, Av. Prof. Egas Moniz, 1649-028 Lisbon, Portugal
| | - Lyn-Marie Birkholtz
- Department of Biochemistry, Genetics and Microbiology, Institute for Sustainable Malaria Control, University of Pretoria, Private Bag X20, Hatfield 0028, South Africa
| | - Janette Reader
- Department of Biochemistry, Genetics and Microbiology, Institute for Sustainable Malaria Control, University of Pretoria, Private Bag X20, Hatfield 0028, South Africa
| | - Mariëtte van der Watt
- Department of Biochemistry, Genetics and Microbiology, Institute for Sustainable Malaria Control, University of Pretoria, Private Bag X20, Hatfield 0028, South Africa
| | - Theresa L. Coetzer
- Wits Research Institute for Malaria, Faculty of Health Sciences, University of the Witwatersrand and National Health Laboratory Service, Johannesburg 2193, South Africa
| | - Sonja Lauterbach
- Wits Research Institute for Malaria, Faculty of Health Sciences, University of the Witwatersrand and National Health Laboratory Service, Johannesburg 2193, South Africa
| | - Alisje Churchyard
- Wits Research Institute for Malaria, Faculty of Health Sciences, University of the Witwatersrand and National Health Laboratory Service, Johannesburg 2193, South Africa
| | - Belinda Bezuidenhout
- Wits Research Institute for Malaria, Faculty of Health Sciences, University of the Witwatersrand and National Health Laboratory Service, Johannesburg 2193, South Africa
| | - Timothy J. Egan
- Department of Chemistry, University of Cape Town, Rondebosch 7701, South Africa
- Institute of Infectious Disease and Molecular Medicine, University of Cape Town, Rondebosch 7701, South Africa
| | - Clive Yeates
- Inpharma
Consultancy, 6 Dudley Hill Close, Welwyn, Hertfordshire AL60QQ, U.K
| | - Sergio Wittlin
- Department of Medical Parasitology and Infection Biology, Swiss Tropical and Public Health Institute, Basel, Switzerland
- University of Basel, Basel, Switzerland
| | - Miguel Prudêncio
- Instituto de Medicina Molecular João Lobo Antunes, Faculdade de Medicina, Universidade de Lisboa, Av. Prof. Egas Moniz, 1649-028 Lisbon, Portugal
| | - Kelly Chibale
- Department of Chemistry, University of Cape Town, Rondebosch 7701, South Africa
- South African Medical Research Council, Drug Discovery and Development Research Unit, University of Cape Town, Rondebosch 7701, South Africa
- Institute of Infectious Disease and Molecular Medicine, University of Cape Town, Rondebosch 7701, South Africa
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6
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Anderson DG, Carmona S, Naidoo K, Coetzer TL, Carr J, Rudnicki DD, Walker RH, Margolis RL, Krause A. Absence of Acanthocytosis in Huntington's Disease-like 2: A Prospective Comparison with Huntington's Disease. Tremor Other Hyperkinet Mov (N Y) 2017; 7:512. [PMID: 29226019 PMCID: PMC5721130 DOI: 10.7916/d81j9pdx] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Download PDF] [Subscribe] [Scholar Register] [Received: 09/25/2017] [Accepted: 11/15/2017] [Indexed: 12/27/2022]
Abstract
Background Huntington’s Disease-like 2 (HDL2) is classified as a neuroacanthocytosis; however, this remains unverified. We aim to determine if acanthocytes are present in HDL2 and whether acanthocytes can differentiate HDL2 from Huntington’s disease (HD). Methods We prospectively compared 13 HD and 12 HDL2 cases against 21 unaffected controls in Johannesburg. Blood smears were prepared using international standards and reviewed by at least two blinded reviewers. An acanthocytosis rate of greater than 1.2% in the dry smear or greater than 3.7% in the wet smear was designated a priori as the threshold for clinical significance based on previously established standards. Flow cytometry was performed on all but four of the cases. Red cell membrane protein analysis was performed on all participants. Results There were 12 HDL2, 13 HD, and 21 controls enrolled. None of the HD or HDL2 participants had defined acanthocytosis or other morphological abnormalities. None of the HD or HDL2 cases had evidence of an abnormal band 3. Discussion Acanthocytosis was not identified in either HDL2 or HD in our patient population. Our results, based on the first prospective study of acanthocytes in HDL2 or HD, suggest that screening for acanthocytes will not help establish the diagnosis of HD or HDL2, nor differentiate between the two disorders and raises the question if HDL2 should be placed within the neuroacanthocytosis syndromes.
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Affiliation(s)
- David G Anderson
- Department of Neurology, The University of the Witwatersrand Donald Gordon Medical Center, Johannesburg, South Africa.,Division of Human Genetics, University of the Witwatersrand, Johannesburg, South Africa
| | - Sergio Carmona
- Department of Molecular Medicine and Haematology, University of the Witwatersrand, Johannesburg, South Africa
| | - Kubendran Naidoo
- Department of Molecular Medicine and Haematology, University of the Witwatersrand, Johannesburg, South Africa
| | - Theresa L Coetzer
- Department of Molecular Medicine and Haematology, University of the Witwatersrand, Johannesburg, South Africa
| | - Jonathan Carr
- Department of Neurology, University of Stellenbosch, Cape Town, South Africa
| | - Dobrila D Rudnicki
- Office of Special Initiatives, National Center for Advancing Translational Sciences, NIH, Bethesda, MD, USA.,Department of Psychiatry and Behavioral Sciences, Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Ruth H Walker
- Department of Neurology, James J. Peters Veterans Affairs Medical Center, New York, NY, USA.,Department of Neurology, Mount Sinai School of Medicine, New York City, NY, USA
| | - Russell L Margolis
- Departments of Psychiatry and Neurology, Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Amanda Krause
- Division of Human Genetics, University of the Witwatersrand, Johannesburg, South Africa.,Division of Human Genetics, National Health Laboratory Service, Johannesburg, South Africa
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7
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Singh K, Okombo J, Brunschwig C, Ndubi F, Barnard L, Wilkinson C, Njogu PM, Njoroge M, Laing L, Machado M, Prudêncio M, Reader J, Botha M, Nondaba S, Birkholtz LM, Lauterbach S, Churchyard A, Coetzer TL, Burrows JN, Yeates C, Denti P, Wiesner L, Egan TJ, Wittlin S, Chibale K. Antimalarial Pyrido[1,2-a]benzimidazoles: Lead Optimization, Parasite Life Cycle Stage Profile, Mechanistic Evaluation, Killing Kinetics, and in Vivo Oral Efficacy in a Mouse Model. J Med Chem 2017; 60:1432-1448. [DOI: 10.1021/acs.jmedchem.6b01641] [Citation(s) in RCA: 30] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Affiliation(s)
- Kawaljit Singh
- Department of Chemistry, University of Cape Town, Rondebosch 7701, South Africa
- South African Medical Research Council Drug Discovery and Development Research Unit, Department of Chemistry
and Institute of Infectious Disease and Molecular Medicine, University of Cape Town, Rondebosch 7701, South Africa
| | - John Okombo
- Department of Chemistry, University of Cape Town, Rondebosch 7701, South Africa
| | - Christel Brunschwig
- Department of Medicine, Division of Clinical Pharmacology, University of Cape Town, Observatory, 7925, South Africa
| | - Ferdinand Ndubi
- Department of Chemistry, University of Cape Town, Rondebosch 7701, South Africa
| | - Linley Barnard
- Department of Chemistry, University of Cape Town, Rondebosch 7701, South Africa
| | - Chad Wilkinson
- Department of Chemistry, University of Cape Town, Rondebosch 7701, South Africa
| | - Peter M. Njogu
- Department of Pharmaceutical Chemistry, University of Nairobi, P.O. Box 19676, Nairobi, 00202, Kenya
| | - Mathew Njoroge
- Department of Medicine, Division of Clinical Pharmacology, University of Cape Town, Observatory, 7925, South Africa
| | - Lizahn Laing
- Department of Medicine, Division of Clinical Pharmacology, University of Cape Town, Observatory, 7925, South Africa
| | - Marta Machado
- Instituto de Medicina Molecular, Faculdade
de Medicina, Universidade de Lisboa, Av. Prof. Egas Moniz, 1649-028 Lisboa, Portugal
| | - Miguel Prudêncio
- Instituto de Medicina Molecular, Faculdade
de Medicina, Universidade de Lisboa, Av. Prof. Egas Moniz, 1649-028 Lisboa, Portugal
| | - Janette Reader
- Department of Biochemistry, Institute for Sustainable
Malaria Control, University of Pretoria, Private Bag X20, Hatfield 0028, South Africa
| | - Mariette Botha
- Department of Biochemistry, Institute for Sustainable
Malaria Control, University of Pretoria, Private Bag X20, Hatfield 0028, South Africa
| | - Sindisiwe Nondaba
- Department of Biochemistry, Institute for Sustainable
Malaria Control, University of Pretoria, Private Bag X20, Hatfield 0028, South Africa
| | - Lyn-Marie Birkholtz
- Department of Biochemistry, Institute for Sustainable
Malaria Control, University of Pretoria, Private Bag X20, Hatfield 0028, South Africa
| | - Sonja Lauterbach
- Wits Research Institute for Malaria, Faculty
of Health Sciences, University of the Witwatersrand and National Health Laboratory Service, Johannesburg 2193, South Africa
| | - Alisje Churchyard
- Wits Research Institute for Malaria, Faculty
of Health Sciences, University of the Witwatersrand and National Health Laboratory Service, Johannesburg 2193, South Africa
| | - Theresa L. Coetzer
- Wits Research Institute for Malaria, Faculty
of Health Sciences, University of the Witwatersrand and National Health Laboratory Service, Johannesburg 2193, South Africa
| | - Jeremy N. Burrows
- Medicines for Malaria Venture, ICC, Route de Pré-Bois 20, P.O. Box 1826, 1215 Geneva, Switzerland
| | - Clive Yeates
- Inpharma Consultancy, 6 Dudley Hill Close, Welwyn, Hertfordshire AL60QQ, U.K
| | - Paolo Denti
- Department of Medicine, Division of Clinical Pharmacology, University of Cape Town, Observatory, 7925, South Africa
| | - Lubbe Wiesner
- Department of Medicine, Division of Clinical Pharmacology, University of Cape Town, Observatory, 7925, South Africa
| | - Timothy J. Egan
- Department of Chemistry, University of Cape Town, Rondebosch 7701, South Africa
| | - Sergio Wittlin
- Swiss Tropical and Public Health Institute, Socinstrasse 57, 4002 Basel, Switzerland
- University of Basel, 4003 Basel, Switzerland
| | - Kelly Chibale
- Department of Chemistry, University of Cape Town, Rondebosch 7701, South Africa
- South African Medical Research Council Drug Discovery and Development Research Unit, Department of Chemistry
and Institute of Infectious Disease and Molecular Medicine, University of Cape Town, Rondebosch 7701, South Africa
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8
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Birkholtz LM, Coetzer TL, Mancama D, Leroy D, Alano P. Discovering New Transmission-Blocking Antimalarial Compounds: Challenges and Opportunities. Trends Parasitol 2016; 32:669-681. [PMID: 27209388 DOI: 10.1016/j.pt.2016.04.017] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2016] [Revised: 04/24/2016] [Accepted: 04/26/2016] [Indexed: 01/08/2023]
Abstract
The ability to target human-mosquito parasite transmission challenges global malaria elimination. However, it is not obvious what a transmission-blocking drug will look like; should it target only parasite transmission stages; be combined with a partner drug killing the pathogenic asexual stages; or kill both the sexual and asexual blood stages, preferably displaying polypharmacology? The development of transmission-blocking antimalarials requires objective analyses of the current strategies. Here, pertinent issues and questions regarding the target candidate profile of a transmission-blocking compound, and its role in malaria elimination strategies, are highlighted and novel perspectives proposed. The essential role of a test cascade that integrates screening and validation strategies to identify next-generation transmission-blocking antimalarials is emphasised.
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Affiliation(s)
- Lyn-Marie Birkholtz
- Department of Biochemistry, Centre for Sustainable Malaria Control, Faculty of Natural and Agricultural Sciences, University of Pretoria, Pretoria, South Africa.
| | - Theresa L Coetzer
- Department of Molecular Medicine and Haematology, Wits Research Institute for Malaria, Faculty of Health Sciences, University of the Witwatersrand, National Health Laboratory Service, Johannesburg, South Africa.
| | - Dalu Mancama
- Department of Biochemistry, Centre for Sustainable Malaria Control, Faculty of Natural and Agricultural Sciences, University of Pretoria, Pretoria, South Africa; Biosciences, Council for Scientific and Industrial Research, Pretoria, South Africa.
| | - Didier Leroy
- Medicines for Malaria Venture, Geneva, Switzerland.
| | - Pietro Alano
- Dipartimento di Malattie Infettive, Parassitarie e Immunomediate, Istituto Superiore di Sanità, Rome, Italy.
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9
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Le Manach C, Paquet T, Brunschwig C, Njoroge M, Han Z, Gonzàlez Cabrera D, Bashyam S, Dhinakaran R, Taylor D, Reader J, Botha M, Churchyard A, Lauterbach S, Coetzer TL, Birkholtz LM, Meister S, Winzeler EA, Waterson D, Witty MJ, Wittlin S, Jiménez-Díaz MB, Santos Martínez M, Ferrer S, Angulo-Barturen I, Street LJ, Chibale K. A Novel Pyrazolopyridine with in Vivo Activity in Plasmodium berghei- and Plasmodium falciparum-Infected Mouse Models from Structure-Activity Relationship Studies around the Core of Recently Identified Antimalarial Imidazopyridazines. J Med Chem 2015; 58:8713-22. [PMID: 26502160 DOI: 10.1021/acs.jmedchem.5b01605] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
Toward improving pharmacokinetics, in vivo efficacy, and selectivity over hERG, structure-activity relationship studies around the central core of antimalarial imidazopyridazines were conducted. This study led to the identification of potent pyrazolopyridines, which showed good in vivo efficacy and pharmacokinetics profiles. The lead compounds also proved to be very potent in the parasite liver and gametocyte stages, which makes them of high interest.
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Affiliation(s)
| | | | - Christel Brunschwig
- Division of Clinical Pharmacology, Department of Medicine, University of Cape Town , Observatory 7925, South Africa
| | - Mathew Njoroge
- Division of Clinical Pharmacology, Department of Medicine, University of Cape Town , Observatory 7925, South Africa
| | | | | | - Sridevi Bashyam
- Syngene International Ltd. , Biocon Park, Plot No. 2 & 3, Bommasandra IV Phase, Jigani Link Road, Bangalore 560099, India
| | - Rajkumar Dhinakaran
- Syngene International Ltd. , Biocon Park, Plot No. 2 & 3, Bommasandra IV Phase, Jigani Link Road, Bangalore 560099, India
| | - Dale Taylor
- Division of Clinical Pharmacology, Department of Medicine, University of Cape Town , Observatory 7925, South Africa
| | - Janette Reader
- Department of Biochemistry, Centre for Sustainable Malaria Control, University of Pretoria , Private bag X20, Hatfield 0028, South Africa
| | - Mariette Botha
- Department of Biochemistry, Centre for Sustainable Malaria Control, University of Pretoria , Private bag X20, Hatfield 0028, South Africa
| | - Alisje Churchyard
- Department of Biochemistry, Centre for Sustainable Malaria Control, University of Pretoria , Private bag X20, Hatfield 0028, South Africa
| | - Sonja Lauterbach
- Department of Biochemistry, Centre for Sustainable Malaria Control, University of Pretoria , Private bag X20, Hatfield 0028, South Africa
| | - Theresa L Coetzer
- Department of Molecular Medicine and Haematology, Wits Research Institute for Malaria, Wits Medical School , 2000 Johannesburg, South Africa
| | - Lyn-Marie Birkholtz
- Department of Biochemistry, Centre for Sustainable Malaria Control, University of Pretoria , Private bag X20, Hatfield 0028, South Africa
| | - Stephan Meister
- School of Medicine, Department of Pediatrics, Pharmacology & Drug Discovery, University of California, San Diego (UCSD) , 9500 Gilman Drive, La Jolla, California 92093, United States
| | - Elizabeth A Winzeler
- School of Medicine, Department of Pediatrics, Pharmacology & Drug Discovery, University of California, San Diego (UCSD) , 9500 Gilman Drive, La Jolla, California 92093, United States
| | - David Waterson
- Medicines for Malaria Venture , ICC, Route de Pré-Bois 20, PO Box 1826, 1215 Geneva, Switzerland
| | - Michael J Witty
- Medicines for Malaria Venture , ICC, Route de Pré-Bois 20, PO Box 1826, 1215 Geneva, Switzerland
| | - Sergio Wittlin
- Swiss Tropical and Public Health Institute , Socinstrasse 57, 4002 Basel, Switzerland.,University of Basel , 4003 Basel, Switzerland
| | - María-Belén Jiménez-Díaz
- GlaxoSmithKline , Tres Cantos Medicines Development Campus, Severo Ochoa, 2, 28760 Tres Cantos, Madrid, Spain
| | - María Santos Martínez
- GlaxoSmithKline , Tres Cantos Medicines Development Campus, Severo Ochoa, 2, 28760 Tres Cantos, Madrid, Spain
| | - Santiago Ferrer
- GlaxoSmithKline , Tres Cantos Medicines Development Campus, Severo Ochoa, 2, 28760 Tres Cantos, Madrid, Spain
| | - Iñigo Angulo-Barturen
- GlaxoSmithKline , Tres Cantos Medicines Development Campus, Severo Ochoa, 2, 28760 Tres Cantos, Madrid, Spain
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10
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Reader J, Botha M, Theron A, Lauterbach SB, Rossouw C, Engelbrecht D, Wepener M, Smit A, Leroy D, Mancama D, Coetzer TL, Birkholtz LM. Nowhere to hide: interrogating different metabolic parameters of Plasmodium falciparum gametocytes in a transmission blocking drug discovery pipeline towards malaria elimination. Malar J 2015; 14:213. [PMID: 25994518 PMCID: PMC4449569 DOI: 10.1186/s12936-015-0718-z] [Citation(s) in RCA: 70] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2015] [Accepted: 04/22/2015] [Indexed: 12/23/2022] Open
Abstract
Background The discovery of malaria transmission-blocking compounds is seen as key to malaria elimination strategies and gametocyte-screening platforms are critical filters to identify active molecules. However, unlike asexual parasite assays measuring parasite proliferation, greater variability in end-point readout exists between different gametocytocidal assays. This is compounded by difficulties in routinely producing viable, functional and stage-specific gametocyte populations. Here, a parallel evaluation of four assay platforms on the same gametocyte populations was performed for the first time. This allowed the direct comparison of the ability of different assay platforms to detect compounds with gametocytocidal activity and revealed caveats in some assay readouts that interrogate different parasite biological functions. Methods Gametocytogenesis from Plasmodium falciparum (NF54) was optimized with a robust and standardized protocol. ATP, pLDH, luciferase reporter and PrestoBlue® assays were compared in context of a set of 10 reference compounds. The assays were performed in parallel on the same gametocyte preparation (except for luciferase reporter lines) using the same drug preparations (48 h). The remaining parameters for each assay were all comparable. Results A highly robust method for generating viable and functional gametocytes was developed and comprehensively validated resulting in an average gametocytaemia of 4 %. Subsequent parallel assays for gametocytocidal activity indicated that different assay platforms were not able to screen compounds with variant chemical scaffolds similarly. Luciferase reporter assays revealed that synchronized stage-specific gametocyte production is essential for drug discovery, as differential susceptibility in various gametocyte developmental populations is evident. Conclusions With this study, the key parameters for assays aiming at testing the gametocytocidal activity of potential transmission blocking molecules against Plasmodium gametocytes were accurately dissected. This first and uniquely comparative study emphasizes differential effects seen with the use of different assay platforms interrogating variant biological systems. Whilst this data is informative from a biological perspective and may provide indications of the drug mode of action, it does highlight the care that must be taken when screening broad-diversity chemotypes with a single assay platform against gametocytes for which the biology is not clearly understood. Electronic supplementary material The online version of this article (doi:10.1186/s12936-015-0718-z) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Janette Reader
- Malaria Parasite Molecular Laboratory, Centre for Sustainable Malaria Control, Department of Biochemistry, University of Pretoria, Private Bag x20, Hatfield, Pretoria, 0028, South Africa.
| | - Mariëtte Botha
- Malaria Parasite Molecular Laboratory, Centre for Sustainable Malaria Control, Department of Biochemistry, University of Pretoria, Private Bag x20, Hatfield, Pretoria, 0028, South Africa.
| | - Anjo Theron
- Biosciences, Council for Scientific and Industrial Research, PO Box 395, Pretoria, 0001, South Africa.
| | - Sonja B Lauterbach
- Plasmodium Molecular Research Unit, Wits Research Institute for Malaria, Department of Molecular Medicine and Haematology, School of Pathology, Faculty of Health Sciences, University of the Witwatersrand and National Health Laboratory Service, Johannesburg, 2193, South Africa.
| | - Claire Rossouw
- Biosciences, Council for Scientific and Industrial Research, PO Box 395, Pretoria, 0001, South Africa.
| | - Dewaldt Engelbrecht
- Plasmodium Molecular Research Unit, Wits Research Institute for Malaria, Department of Molecular Medicine and Haematology, School of Pathology, Faculty of Health Sciences, University of the Witwatersrand and National Health Laboratory Service, Johannesburg, 2193, South Africa.
| | - Melanie Wepener
- Plasmodium Molecular Research Unit, Wits Research Institute for Malaria, Department of Molecular Medicine and Haematology, School of Pathology, Faculty of Health Sciences, University of the Witwatersrand and National Health Laboratory Service, Johannesburg, 2193, South Africa.
| | - Annél Smit
- Malaria Parasite Molecular Laboratory, Centre for Sustainable Malaria Control, Department of Biochemistry, University of Pretoria, Private Bag x20, Hatfield, Pretoria, 0028, South Africa.
| | - Didier Leroy
- Medicines for Malaria Venture, Geneva, Switzerland.
| | - Dalu Mancama
- Biosciences, Council for Scientific and Industrial Research, PO Box 395, Pretoria, 0001, South Africa.
| | - Theresa L Coetzer
- Plasmodium Molecular Research Unit, Wits Research Institute for Malaria, Department of Molecular Medicine and Haematology, School of Pathology, Faculty of Health Sciences, University of the Witwatersrand and National Health Laboratory Service, Johannesburg, 2193, South Africa.
| | - Lyn-Marie Birkholtz
- Malaria Parasite Molecular Laboratory, Centre for Sustainable Malaria Control, Department of Biochemistry, University of Pretoria, Private Bag x20, Hatfield, Pretoria, 0028, South Africa.
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11
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Blanc M, Coetzer TL, Blackledge M, Haertlein M, Mitchell EP, Forsyth VT, Jensen MR. Intrinsic disorder within the erythrocyte binding-like proteins from Plasmodium falciparum. Biochimica et Biophysica Acta (BBA) - Proteins and Proteomics 2014; 1844:2306-14. [DOI: 10.1016/j.bbapap.2014.09.023] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/07/2014] [Revised: 09/18/2014] [Accepted: 09/26/2014] [Indexed: 10/24/2022]
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12
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Birkholtz LM, LeRoy D, Reader J, Botha M, Mancama D, Coetzer TL. Differential activity of novel gametocytocidal compounds: drug mode-of-action and ex vivo efficacy. Malar J 2014. [PMCID: PMC4179293 DOI: 10.1186/1475-2875-13-s1-p13] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
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13
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Swierczek S, Agarwal AM, Naidoo K, Lorenzo FR, Whisenant J, Nussenzveig RH, Agarwal N, Coetzer TL, Prchal JT. Novel exon 2 α spectrin mutation and intragenic crossover: three morphological phenotypes associated with four distinct α spectrin defects. Haematologica 2013; 98:1972-9. [PMID: 24077844 DOI: 10.3324/haematol.2013.086629] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Abstract
Hereditary pyropoikilocytosis is a severe hemolytic anemia caused by spectrin deficiency and defective spectrin dimer self-association, typically found in African populations. We describe two Utah families of northern European ancestry including 2 propositi with atypical non-microcytic hereditary pyropoikilocytosis, 7 hereditary elliptocytosis members and one asymptomatic carrier. The underlying molecular defect is a novel mutation in the alpha(α) spectrin gene, SPTA(R34P) that impairs spectrin tetramer formation. It is inherited in trans to the hypomorphic SPTA(αLELY) in the 2 propositi and 5 of 7 hereditary elliptocytosis individuals indicating that SPTA(αLELY) is not the sole determinant of the variable clinical expression. α Spectrin mRNA was mildly decreased in all hereditary elliptocytosis subjects, whereas both hereditary pyropoikilocytosis propositi had a severe decrease to ~10% of normal. Genotyping identified a unique SPTA intragenic crossover and uniparental disomy in one hereditary elliptocytosis individual. Two additional crossover events demonstrated the susceptibility of SPTA gene to rearrangement and revealed a novel segregation of the two SPTA(αLELY) mutations. We conclude that the profound phenotypic heterogeneity in these families can be attributed to the SPTA(R34P) mutation in combination with: 1) inheritance in trans of either SPTA(αLELY); or 2) the wild-type SPTA; 3) a decrease of α spectrin mRNA; and 4) SPTA intragenic crossover.
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14
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Durand PM, Hazelhurst S, Coetzer TL. Evolutionary rates at codon sites may be used to align sequences and infer protein domain function. BMC Bioinformatics 2010; 11:151. [PMID: 20334658 PMCID: PMC2851608 DOI: 10.1186/1471-2105-11-151] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2009] [Accepted: 03/24/2010] [Indexed: 12/04/2022] Open
Abstract
Background Sequence alignments form part of many investigations in molecular biology, including the determination of phylogenetic relationships, the prediction of protein structure and function, and the measurement of evolutionary rates. However, to obtain meaningful results, a significant degree of sequence similarity is required to ensure that the alignments are accurate and the inferences correct. Limitations arise when sequence similarity is low, which is particularly problematic when working with fast-evolving genes, evolutionary distant taxa, genomes with nucleotide biases, and cases of convergent evolution. Results A novel approach was conceptualized to address the "low sequence similarity" alignment problem. We developed an alignment algorithm termed FIRE (Functional Inference using the Rates of Evolution), which aligns sequences using the evolutionary rate at codon sites, as measured by the dN/dS ratio, rather than nucleotide or amino acid residues. FIRE was used to test the hypotheses that evolutionary rates can be used to align sequences and that the alignments may be used to infer protein domain function. Using a range of test data, we found that aligning domains based on evolutionary rates was possible even when sequence similarity was very low (for example, antibody variable regions). Furthermore, the alignment has the potential to infer protein domain function, indicating that domains with similar functions are subject to similar evolutionary constraints. These data suggest that an evolutionary rate-based approach to sequence analysis (particularly when combined with structural data) may be used to study cases of convergent evolution or when sequences have very low similarity. However, when aligning homologous gene sets with sequence similarity, FIRE did not perform as well as the best traditional alignment algorithms indicating that the conventional approach of aligning residues as opposed to evolutionary rates remains the method of choice in these cases. Conclusions FIRE provides proof of concept that it is possible to align sequences and infer domain function by using evolutionary rates rather than residue similarity. This represents a new approach to sequence analysis with a wide range of potential applications in molecular biology.
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Affiliation(s)
- Pierre M Durand
- Evolutionary Medicine Unit, University of the Witwatersrand and National Health Laboratory Service, Johannesburg, South Africa.
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15
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Durand PM, Naidoo K, Coetzer TL. Evolutionary patterning: a novel approach to the identification of potential drug target sites in Plasmodium falciparum. PLoS One 2008; 3:e3685. [PMID: 18997863 PMCID: PMC2577034 DOI: 10.1371/journal.pone.0003685] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2008] [Accepted: 10/17/2008] [Indexed: 11/19/2022] Open
Abstract
Malaria continues to be the most lethal protozoan disease of humans. Drug development programs exhibit a high attrition rate and parasite resistance to chemotherapeutic drugs exacerbates the problem. Strategies that limit the development of resistance and minimize host side-effects are therefore of major importance. In this study, a novel approach, termed evolutionary patterning (EP), was used to identify suitable drug target sites that would minimize the emergence of parasite resistance. EP uses the ratio of non-synonymous to synonymous substitutions (ω) to assess the patterns of evolutionary change at individual codons in a gene and to identify codons under the most intense purifying selection (ω≤0.1). The extreme evolutionary pressure to maintain these residues implies that resistance mutations are highly unlikely to develop, which makes them attractive chemotherapeutic targets. Method validation included a demonstration that none of the residues providing pyrimethamine resistance in the Plasmodium falciparum dihydrofolate reductase enzyme were under extreme purifying selection. To illustrate the EP approach, the putative P. falciparum glycerol kinase (PfGK) was used as an example. The gene was cloned and the recombinant protein was active in vitro, verifying the database annotation. Parasite and human GK gene sequences were analyzed separately as part of protozoan and metazoan clades, respectively, and key differences in the evolutionary patterns of the two molecules were identified. Potential drug target sites containing residues under extreme evolutionary constraints were selected. Structural modeling was used to evaluate the functional importance and drug accessibility of these sites, which narrowed down the number of candidates. The strategy of evolutionary patterning and refinement with structural modeling addresses the problem of targeting sites to minimize the development of drug resistance. This represents a significant advance for drug discovery programs in malaria and other infectious diseases.
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Affiliation(s)
- Pierre M Durand
- Department of Molecular Medicine and Haematology, University of the Witwatersrand and National Health Laboratory Service, Johannesburg, South Africa.
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17
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Li X, Chen H, Khan AA, Lauterbach SB, Lanzillotti R, Rai PR, Kane RS, Coetzer TL, Chishti AH. Receptor-based identification of an inhibitory peptide against blood stage malaria. Biochem Biophys Res Commun 2008; 376:489-93. [PMID: 18793615 DOI: 10.1016/j.bbrc.2008.09.011] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2008] [Accepted: 09/03/2008] [Indexed: 11/28/2022]
Abstract
Plasmodium falciparum uses multiple host receptors to attach and invade human erythrocytes. Glycophorins have been implicated as receptors for parasite invasion in human erythrocytes. Here, we screened a phage display cDNA library of P. falciparum (FCR3, a sialic acid-dependent strain) using purified glycophorins and erythrocytes as bait. Several phage clones were identified that bound to immobilized glycophorins and contained the same 74 bp insert encoding the 7-amino acids sequence ETTLKSF. A similar screen using intact human erythrocytes in solution identified additional phage clones containing the same 7-amino acids sequence. Using ELISA and immunofluorescence, direct binding of ETTLKSF peptide to glycophorins and erythrocytes was confirmed. Pull-down and protease treatment assays suggest that ETTLKSF peptide specifically interacts with glycophorin C. The synthetic ETTLKSF peptide partially blocks merozoite invasion in human erythrocytes. Further characterization of ETTLKSF peptide could lead to the development of a novel class of inhibitors against the blood stage malaria.
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Affiliation(s)
- Xuerong Li
- Department of Pharmacology and Cancer Center, University of Illinois College of Medicine, 909 South Wolcott Avenue, Room 5100, MC 704, Chicago, IL 60612, USA
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Lauterbach SB, Coetzer TL. The M18 aspartyl aminopeptidase of Plasmodium falciparum binds to human erythrocyte spectrin in vitro. Malar J 2008; 7:161. [PMID: 18721457 PMCID: PMC2543045 DOI: 10.1186/1475-2875-7-161] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2007] [Accepted: 08/22/2008] [Indexed: 11/10/2022] Open
Abstract
Background During erythrocytic schizogony, Plasmodium falciparum interacts with the human erythrocyte membrane when it enters into, grows within and escapes from the erythrocyte. An interaction between the P. falciparum M18 aspartyl aminopeptidase (PfM18AAP) and the human erythrocyte membrane protein spectrin was recently identified using phage display technology. In this study, recombinant (r) PfM18AAP was characterized and the interaction between the enzyme and spectrin, as well as other erythrocyte membrane proteins, analyzed. Methods rPfM18AAP was produced as a hexahistidine-fusion protein in Escherichia coli and purified using magnetic bead technology. The pI of the enzyme was determined by two-dimensional gel electrophoresis and the number of subunits in the native enzyme was estimated from Ferguson plots. The enzymatic activity over a pH and temperature range was tested by a coupled enzyme assay. Blot overlays were performed to validate the spectrin-PfM18AAP interaction, as well as identify additional interactions between the enzyme and other erythrocyte membrane proteins. Sequence analysis identified conserved amino acids that are expected to be involved in cofactor binding, substrate cleavage and quaternary structure stabilization. Results rPfM18AAP has a molecular weight of ~67 kDa and the enzyme separated as three entities with pI 6.6, 6.7 and 6.9. Non-denaturing gel electrophoresis indicated that rPfM18AAP aggregated into oligomers. An in vitro coupled enzyme assay showed that rPfM18AAP cleaved an N-terminal aspartate from a tripeptide substrate with maximum enzymatic activity at pH 7.5 and 37°C. The spectrin-binding region of PfM18AAP is not found in Homo sapiens, Saccharomyces cerevisiae and otherPlasmodium species homologues. Amino acids expected to be involved in cofactor binding, substrate cleavage and quaternary structure stabilization, are conserved. Blot overlays with rPfM18AAP against spectrin and erythrocyte membrane proteins indicated that rPfM18AAP binds to spectrin, as well as to protein 4.1, protein 4.2, actin and glyceraldehyde 3-phosphate dehydrogenase. Conclusion Studies characterizing rPfM18AAP showed that this enzyme interacts with erythrocyte spectrin and other membrane proteins. This suggests that, in addition to its proposed role in hemoglobin digestion, PfM18AAP performs other functions in the erythrocyte host and can utilize several substrates, which highlights the multifunctional role of malaria enzymes.
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Affiliation(s)
- Sonja B Lauterbach
- Department of Molecular Medicine and Haematology, National Health Laboratory Service, School of Pathology, University of the Witwatersrand, Parktown, Johannesburg 2193, Republic of South Africa
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19
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Durand PM, Coetzer TL. Pyruvate kinase deficiency in a South African kindred caused by a 1529A mutation in the PK-LR gene. S Afr Med J 2008; 98:456-457. [PMID: 18683378] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/26/2023] Open
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20
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Lanzillotti R, Coetzer TL. The 10 kDa domain of human erythrocyte protein 4.1 binds the Plasmodium falciparum EBA-181 protein. Malar J 2006; 5:100. [PMID: 17087826 PMCID: PMC1635724 DOI: 10.1186/1475-2875-5-100] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2006] [Accepted: 11/06/2006] [Indexed: 11/12/2022] Open
Abstract
Background Erythrocyte invasion by Plasmodium falciparum parasites represents a key mechanism during malaria pathogenesis. Erythrocyte binding antigen-181 (EBA-181) is an important invasion protein, which mediates a unique host cell entry pathway. A novel interaction between EBA-181 and human erythrocyte membrane protein 4.1 (4.1R) was recently demonstrated using phage display technology. In the current study, recombinant proteins were utilized to define and characterize the precise molecular interaction between the two proteins. Methods 4.1R structural domains (30, 16, 10 and 22 kDa domain) and the 4.1R binding region in EBA-181 were synthesized in specific Escherichia coli strains as recombinant proteins and purified using magnetic bead technology. Recombinant proteins were subsequently used in blot-overlay and histidine pull-down assays to determine the binding domain in 4.1R. Results Blot overlay and histidine pull-down experiments revealed specific interaction between the 10 kDa domain of 4.1R and EBA-181. Binding was concentration dependent as well as saturable and was abolished by heat denaturation of 4.1R. Conclusion The interaction of EBA-181 with the highly conserved 10 kDa domain of 4.1R provides new insight into the molecular mechanisms utilized by P. falciparum during erythrocyte entry. The results highlight the potential multifunctional role of malaria invasion proteins, which may contribute to the success of the pathogenic stage of the parasite's life cycle.
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Affiliation(s)
- Roberto Lanzillotti
- Department of Molecular Medicine and Haematology, National Health Laboratory Service, School of Pathology, University of the Witwatersrand, Parktown, Johannesburg, 2193, South Africa
| | - Theresa L Coetzer
- Department of Molecular Medicine and Haematology, National Health Laboratory Service, School of Pathology, University of the Witwatersrand, Parktown, Johannesburg, 2193, South Africa
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21
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Durand PM, Oelofse AJ, Coetzer TL. An analysis of mobile genetic elements in three Plasmodium species and their potential impact on the nucleotide composition of the P. falciparum genome. BMC Genomics 2006; 7:282. [PMID: 17083741 PMCID: PMC1636048 DOI: 10.1186/1471-2164-7-282] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2006] [Accepted: 11/04/2006] [Indexed: 01/09/2023] Open
Abstract
BACKGROUND The completed genome sequences of the malaria parasites P. falciparum, P. y. yoelii and P. vivax have revealed some unusual features. P. falciparum contains the most AT rich genome sequenced so far--over 90% in some regions. In comparison, P. y. yoelii is approximately 77% and P. vivax is approximately 55% AT rich. The evolutionary reasons for these findings are unknown. Mobile genetic elements have a considerable impact on genome evolution but a thorough investigation of these elements in Plasmodium has not been undertaken. We therefore performed a comprehensive genome analysis of these elements and their derivatives in the three Plasmodium species. RESULTS Whole genome analysis was performed using bioinformatic methods. Forty potential protein encoding sequences with features of transposable elements were identified in P. vivax, eight in P. y. yoelii and only six in P. falciparum. Further investigation of the six open reading frames in P. falciparum revealed that only one is potentially an active mobile genetic element. Most of the open reading frames identified in all three species are hypothetical proteins. Some represent annotated host proteins such as the putative telomerase reverse transcriptase genes in P. y. yoelii and P. falciparum. One of the P. vivax open reading frames identified in this study demonstrates similarity to telomerase reverse transcriptase and we conclude it to be the orthologue of this gene. CONCLUSION There is a divergence in the frequencies of mobile genetic elements in the three Plasmodium species investigated. Despite the limitations of whole genome analytical methods, it is tempting to speculate that mobile genetic elements might have been a driving force behind the compositional bias of the P. falciparum genome.
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Affiliation(s)
- Pierre M Durand
- Department of Molecular Medicine and Haematology, University of the Witwatersrand Medical School and National Health Laboratory Service, York Road, Parktown, 2193, South Africa
| | - Andries J Oelofse
- Wits Bioinformatics, University Corner building, University of the Witwatersrand, Johannesburg, 2017, South Africa
| | - Theresa L Coetzer
- Department of Molecular Medicine and Haematology, University of the Witwatersrand Medical School and National Health Laboratory Service, York Road, Parktown, 2193, South Africa
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22
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Chen GL, Liu E, Naidoo K, Popat U, Coetzer TL, Prchal JT. Idiopathic myelofibrosis without dacryocytes. Haematologica 2006; 91:ECR29. [PMID: 16785132] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/10/2023] Open
Abstract
Idiopathic myelofibrosis (IMF) typically presents with marrow fibrosis, splenomegaly, progressive anemia, and a leukoerythroblastic blood smear with dacryocytes. We present a patient with IMF who did not have dacryocytes.
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Affiliation(s)
- George L Chen
- Baylor College of Medicine, Department of Medicine, Division of Hematology/Oncology, Houston, Texas, USA.
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23
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Lanzillotti R, Coetzer TL. Myosin-like sequences in the malaria parasite Plasmodium falciparum bind human erythrocyte membrane protein 4.1. Haematologica 2004; 89:1168-71. [PMID: 15477199] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/30/2023] Open
Abstract
BACKGROUND AND OBJECTIVES Plasmodium falciparum malaria is one of the most lethal infectious diseases afflicting humanity. During development within the erythrocyte, P. falciparum induces significant modifications to the structure and function of the human erythrocyte membrane. This study focused on the identification of new protein-protein interactions between host and parasite. DESIGN AND METHODS A novel application of in vitro display technology was used: P. falciparum phage display expression libraries were screened against purified human erythrocyte protein 4.1. DNA sequencing and bioinformatic analyses were used to identify parasite proteins that bind protein 4.1. RESULTS P. falciparum proteins displaying strong binding specificity toward protein 4.1 included five hypothetical proteins, erythrocyte binding antigen-175, erythrocyte binding ligand-1 like protein and a putative serine/threonine kinase. A common binding motif displaying homology to muscle myosin and neurofilament sequences was also identified in four of the eight proteins. INTERPRETATION AND CONCLUSIONS These proteins are potentially involved in the invasion and/or release, as well as the growth and survival of malaria parasites during development with the red blood cell. The characterization of novel protein interactions between P. falciparum and erythrocyte membrane protein 4.1 will lead to a better understanding of malaria pathogenesis and parasite biology.
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Affiliation(s)
- Roberto Lanzillotti
- Department of Molecular Medicine and Haematology, National Health Laboratory Service, School of Pathology, University of the Witwatersrand, Parktown, Johannesburg 2193, South Africa
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24
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Lauterbach SB, Lanzillotti R, Coetzer TL. Construction and use of Plasmodium falciparum phage display libraries to identify host parasite interactions. Malar J 2003; 2:47. [PMID: 14678570 PMCID: PMC317474 DOI: 10.1186/1475-2875-2-47] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2003] [Accepted: 12/17/2003] [Indexed: 11/10/2022] Open
Abstract
Background The development of Plasmodium falciparum within human erythrocytes induces a wide array of changes in the ultrastructure, function and antigenic properties of the host cell. Numerous proteins encoded by the parasite have been shown to interact with the erythrocyte membrane. The identification of new interactions between human erythrocyte and P. falciparum proteins has formed a key area of malaria research. To circumvent the difficulties provided by conventional protein techniques, a novel application of the phage display technology was utilised. Methods P. falciparum phage display libraries were created and biopanned against purified erythrocyte membrane proteins. The identification of interacting and in-frame amino acid sequences was achieved by sequencing parasite cDNA inserts and performing bioinformatic analyses in the PlasmoDB database. Results Following four rounds of biopanning, sequencing and bioinformatic investigations, seven P. falciparum proteins with significant binding specificity toward human erythrocyte spectrin and protein 4.1 were identified. The specificity of these P. falciparum proteins were demonstrated by the marked enrichment of the respective in-frame binding sequences from a fourth round phage display library. Conclusion The construction and biopanning of P. falciparum phage display expression libraries provide a novel approach for the identification of new interactions between the parasite and the erythrocyte membrane.
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Affiliation(s)
- Sonja B Lauterbach
- Department of Molecular Medicine and Haematology, National Health Laboratory Services, School of Pathology, University of the Witwatersrand, Parktown, Johannesburg 2193, South Africa
| | - Roberto Lanzillotti
- Department of Molecular Medicine and Haematology, National Health Laboratory Services, School of Pathology, University of the Witwatersrand, Parktown, Johannesburg 2193, South Africa
| | - Theresa L Coetzer
- Department of Molecular Medicine and Haematology, National Health Laboratory Services, School of Pathology, University of the Witwatersrand, Parktown, Johannesburg 2193, South Africa
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25
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Scott CS, van Zyl D, Ho E, Meyersfeld D, Ruivo L, Mendelow BV, Coetzer TL. Automated detection of malaria-associated intraleucocytic haemozoin by Cell-Dyn CD4000 depolarization analysis. Clin Lab Haematol 2003; 25:77-86. [PMID: 12641610 DOI: 10.1046/j.1365-2257.2003.00496.x] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Laboratory tests for malaria are only performed if there is clinical suspicion of the disease, and a missed diagnosis contributes substantially to morbidity and mortality. Malaria parasites produce haemozoin, which is able to depolarize light and this allows the automated detection of malaria during routine complete blood count analysis (CBC) with some Abbott Cell-Dyn instruments. In this study, we evaluated the Cell-Dyn CD4000 with 831 blood samples submitted for malaria investigations. Samples were categorized as malaria negative (n = 417), convalescent malaria (n = 64) or malaria positive (n = 350) by reference to thin/thick film microscopy, 'rapid test' procedures, polymerase chain reaction analysis and clinical history. With regard to CD4000 depolarization analysis, a malaria positive CD4000 pattern was ascribed to samples that showed one or more abnormal depolarizing purple events, which corresponded to monocytes containing ingested malaria pigment (haemozoin). Positive CD4000 patterns were observed in 11 of 417, 50 of 64 and 281 of 350 of malaria negative, convalescent malaria and malaria positive samples respectively. The specificity and positive predictive values for malaria (active and convalescent) were very high (97.4 and 96.8%, respectively), while sensitivity and negative predictive values were 80.0 and 83.0% respectively. Depolarization analysis was particularly effective for Plasmodium falciparum malaria but there was lower detection sensitivity for White compared with Black African patients. CD4000 90 degrees depolarization vs 0 degrees analysis revealed a proportion of samples with small nonleucocyte-associated depolarizing particles. Appearance of such events in the form of a discrete cluster was associated with P. vivax rather than P. falciparum infection.
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Affiliation(s)
- C S Scott
- Abbott Diagnostics, Wiesbaden-Delkenheim, Germany.
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26
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Scott CS, Van Zyl D, Ho E, Ruivo L, Mendelow B, Coetzer TL. Thrombocytopenia in patients with malaria: automated analysis of optical platelet counts and platelet clumps with the Cell Dyn CD4000 analyser. Clin Lab Haematol 2002; 24:295-302. [PMID: 12358891 DOI: 10.1046/j.1365-2257.2002.00466.x] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Platelet counts and automated detection of platelet clumps were evaluated by optical analysis with the Abbott CD4000 analyser (Abbott Diagnostics, Santa Clara, CA, USA) in this South African study of 828 samples referred for malaria investigations. Based on microscopy (Micro) and rapid tests (RT) for HRP2 protein and parasite-associated LDH, malaria negative samples (n = 417) were defined as Micro-, RT-. Convalescent cases (n = 64) were Micro-, RT+ and had a recent record of positive microscopy. Malaria positive cases were subdivided into Micro+ (n = 315) and Micro-, RT+, PCR+ (polymerase chain reaction) (n = 32) subgroups. The mean platelet count for Micro+ cases (89.7 x 10(9)/l) was significantly lower than both the malaria negative (mean 212.6 x 10(9)/l) and convalescent malaria (mean 152.8 x 10(9)/l) groups; 89% of microscopy positive cases were thrombocytopenic (< 150 x 10(9)/l) and 30% had severe thrombocytopenia (< 50 x 10(9)/l). For comparison, 32% of the 417 malaria negative samples were thrombocytopenic and 6% of these were severe. Two thirds of samples with parasitaemia above 10% had platelet counts of < 50 x 10(9)/l while the counts were largely independent of parasite numbers when the parasitaemia was below 10%. Thirty percent of samples with microscopically detectable parasites had a PltClmp flag compared to 13% of the malaria negative group but, when the actual platelet count was taken into account, it became apparent that appearance of the flag was primarily associated with thrombocytopenia per se rather than malaria status. In most samples with a PltClmp flag, the CD4000 optical platelet clump 'signature' was indicative of small platelet aggregates and giant platelets. Morphological examination confirmed the presence of varying numbers of small platelet aggregates (3-12 individual platelets), often together with increased giant platelets, in many samples with a PltClmp flag. The observations suggest that while patients with malaria may be predisposed to the development of thrombocytopenia, a reduced platelet count in some patients may also be due in part to pseudo-thrombocytopenia.
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Affiliation(s)
- C S Scott
- Department of Molecular Medicine and Haematology, South African Institute for Medical Research, University of the Witwatersrand, Johannesburg, South Africa.
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27
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Scott CS, Van Zyl D, Ho E, Ruivo L, Kunz D, Coetzer TL. Patterns of pseudo-reticulocytosis in malaria: fluorescent analysis with the Cell-Dyn CD4000. Clin Lab Haematol 2002; 24:15-20. [PMID: 11843893 DOI: 10.1046/j.1365-2257.2002.00426.x] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
This study of Plasmodium falciparum malaria evaluated patterns of fluorescent reticulocyte measurements as determined with the Abbott Cell-Dyn CD4000. The parasitaemia of positive samples (n=180) ranged from 0.04% to 25.5%, with those (19/180) showing gametocytes having lower parasitaemia levels (mean 0.31%, median 0.2%) compared to those that did not (mean 2.59%, median 0.8%). There was a reasonable association (R2=0.60) between parasitaemia level and CD4000 reticulocyte percentages, although there was overall a small statistical bias towards higher parasitaemia estimates determined microscopically. Consistently high immature reticulocyte fraction (IRF) values of >0.5 were observed in cases with a parasitaemia exceeding 5%, while samples with lower parasitaemia levels showed more variable IRF values. Visual examination of CD4000 reticulocyte histograms revealed that 81/100 malaria-positive samples with an IRF above 0.5 showed the presence of a fluorescent population 'spike' consistent with the staining of intracellular malaria parasites. Only three of the 80 malaria-positive samples with an IRF below 0.5, and none of the 237 malaria-negative samples, showed this histogram pattern. These observations indicate that samples with malaria parasites give erroneously high CD4000 reticulocyte estimates that essentially comprise the sum total of true reticulocytes and parasite-infected red cells (pseudo-reticulocytes). This limitation is common to all automated reticulocyte procedures but recognizing the differences between homogenous staining parasitized red cells and heterogeneous staining reticulocytes has potential applications in monitoring parasitaemia levels both at patient presentation and during subsequent treatment.
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Affiliation(s)
- C S Scott
- Department of Molecular Medicine and Haematology, South African Institute for Medical Research, University of the Witwatersrand, Johannesburg, South Africa
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28
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Bracher NA, Lyons CA, Wessels G, Mansvelt E, Coetzer TL. Band 3 Cape Town (E90K) causes severe hereditary spherocytosis in combination with band 3 Prague III. Br J Haematol 2001; 113:689-93. [PMID: 11380459 DOI: 10.1046/j.1365-2141.2001.02800.x] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Hereditary spherocytosis (HS) is an inherited haemolytic anaemia, characterized by spheroidal, osmotically fragile red blood cells. This disorder exhibits heterogeneity in terms of both clinical severity and underlying molecular defect. We have studied a South African Cape Coloured individual with severe HS owing to a band 3 deficiency caused by two mutations, occurring in trans, in the band 3 gene: a novel variant that we have designated band 3 Cape Town and a previously described mutation, band 3 Prague III. Analysis of erythrocyte membrane proteins indicated a deficiency of both band 3 and protein 4.2, as well as a decreased functional capacity of band 3 to transport anions. Band 3 Cape Town is defined by a GAG-->AAG point mutation at codon 90, substituting a glutamic acid with a lysine in the cytoplasmic domain of the molecule, while band 3 Prague III is a codon 870 CGG-->TGG point mutation, replacing an arginine with a tryptophan in the transmembrane region of band 3. mRNA is transcribed from both mutant alleles, implying that mutant proteins are synthesized, but are either degraded prior to membrane incorporation or insertion is impaired. We conclude that the combination of these two mutations exacerbated the clinical presentation of the proband.
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Affiliation(s)
- N A Bracher
- Department of Molecular Medicine and Haematology, South African Institute for Medical Research, School of Pathology, University of the Witwatersrand, Johannesburg, South Africa
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29
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Affiliation(s)
- BV Mendelow
- Department of Haematology, School of Pathology, Medical School, York Road, Parktown 2193, South Africa
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30
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Mendelow BV, Lyons C, Nhlangothi P, Tana M, Munster M, Wypkema E, Liebowitz L, Marshall L, Scott S, Coetzer TL. Automated malaria detection by depolarization of laser light. Br J Haematol 1999; 104:499-503. [PMID: 10086786 DOI: 10.1046/j.1365-2141.1999.01199.x] [Citation(s) in RCA: 61] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
Anecdotal experience with full blood count (FBC) technology incorporating analysis of depolarized laser light (DLL) for the enumeration of eosinophils showed that malaria infection generated unusual distributions in the white cell channels. The objective of this study was to identify and define criteria for a diagnosis of malaria using this technology. To determine sensitivity, specificity, and positive and negative predictive values, 224 directed samples referred specifically for malaria were used; true positives were defined as those in which malaria was identified by microscopic and/or immunological methods. For the DLL method, positive was defined as one or more large mononuclear cell(s) for which the 90 degrees depolarized signal exceeded the 90 degrees polarized signal. To determine possible utility in a routine haematology laboratory setting, 220 random undirected FBC samples were evaluated for possible malaria infection by the DLL method. Of the 224 directed samples, 95 were malaria positive as determined by microscopic and/or immunological methods, and 129 were negative. For the DLL method, overall sensitivity was 72% (90% in the case of Black Africans), and specificity 96%. Positive and negative predictive values overall were 93% and 82% respectively. In the utility study a single positive result was identified among the 220 samples studied. This was found to be from a patient with malaria. The detection of unexpected malaria by automated screening FBC analysis could substantially lower the mortality and morbidity from unascertained infection, especially in indigenous African peoples.
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Affiliation(s)
- B V Mendelow
- Department of Haematology, University of the Witwatersrand and the South African Institute for Medical Research, Johannesburg
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31
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Burke JP, Van Zyl D, Zail SS, Coetzer TL. Reduced spectrin-ankyrin binding in a South African hereditary elliptocytosis kindred homozygous for spectrin St Claude. Blood 1998; 92:2591-2. [PMID: 9746802] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023] Open
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32
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Coetzer TL, Beeton L, van Zyl D, Field SP, Agherdien A, Smart E, Daniels GL. Southeast Asian ovalocytosis in a South African kindred with hemolytic anemia. Blood 1996; 87:1656-7. [PMID: 8608262] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023] Open
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33
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Beeton L, Prchal JT, Coetzer TL. A TaqI polymorphism in the human erythroid beta spectrin gene. Hum Genet 1995; 95:365-6. [PMID: 7868137 DOI: 10.1007/bf00225212] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
Human erythroid spectrin consists of an alpha beta heterodimer. Abnormalities of spectrin are a common cause of hereditary haemolytic anaemias such as hereditary elliptocytosis (HE) and hereditary spherocytosis (HS). To identify the spectrin gene mutation one needs initially to establish which of the spectrin subunits is defective. For this purpose, the beta spectrin restriction fragment length polymorphism (RFLP) we describe here will be useful in linkage analysis. The elucidation of an Ala-->Gly beta spectrin gene mutation in a family with HE, highlights the importance of this TaqI polymorphism in establishing linkage.
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Affiliation(s)
- L Beeton
- Department of Haematology, School of Pathology, University of the Witwatersrand, South Africa
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34
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Hassoun H, Coetzer TL, Vassiliadis JN, Sahr KE, Maalouf GJ, Saad ST, Catanzariti L, Palek J. A novel mobile element inserted in the alpha spectrin gene: spectrin dayton. A truncated alpha spectrin associated with hereditary elliptocytosis. J Clin Invest 1994; 94:643-8. [PMID: 8040317 PMCID: PMC296141 DOI: 10.1172/jci117380] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023] Open
Abstract
Nonviral retrotransposons, retropseudogenes, and short interspersed nuclear elements (SINEs) are mobile DNA segments capable of transposition to new genomic locations, where they may alter gene expression. De novo integration into specific genes has been described in both germ and somatic cells. We report a family with hereditary elliptocytosis and pyropoikilocytosis associated with a truncated alpha-spectrin protein. We present the biochemical characteristics of this abnormal protein and show that the alpha-spectrin gene is disrupted by a mobile element resulting in exon skipping. This element causes duplication of the insertion site and is terminated by a long poly-A tail downstream of multiple consensus polyadenylation signals. Southern blot analysis of human genomic DNA, using this element as probe, reveals one to three copies per individual. This element has no homology to any previously reported sequence and therefore appears to be a member of a novel family of mobile elements.
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Affiliation(s)
- H Hassoun
- Department of Biomedical Research, St. Elizabeth's Hospital of Boston, Tufts University Medical School, Massachusetts 02135
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35
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Sahr KE, Coetzer TL, Moy LS, Derick LH, Chishti AH, Jarolim P, Lorenzo F, Miraglia del Giudice E, Iolascon A, Gallanello R. Spectrin cagliari. an Ala-->Gly substitution in helix 1 of beta spectrin repeat 17 that severely disrupts the structure and self-association of the erythrocyte spectrin heterodimer. J Biol Chem 1993; 268:22656-62. [PMID: 8226774] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023] Open
Abstract
The spectrin tetramer, the principal structural element of the red cell membrane skeleton, is formed by stable head-to-head self-association of two spectrin heterodimers. The self-association site appears to be formed by interactions between helices 1 and 2 of beta spectrin repeat 17 of one dimer with helix 3 of alpha spectrin repeat 1 of the other dimer to form two combined alpha-beta triple-helical segments. The head of the heterodimer appears to involve similar intradimer interactions. We describe the first example of an amino acid substitution in helix 1 of this combined alpha-beta triple-helical segment, which, although relatively minor, profoundly impairs tetramer formation. Strikingly, low angle rotary shadowing electron microscopy of isolated spectrin dimers reveals that this mutation also severely disrupts the head of the heterodimer causing it to be open. Following linkage studies which were most consistent with a beta spectrin gene mutation, a nucleotide change was identified in codon 2018, resulting in an Ala-->Gly substitution in the first helical domain of beta spectrin repeat 17. Because glycine is a strong helix breaker, this change is predicted to disrupt the conformation of this helical domain. Our results indicate that this helical domain must play direct roles in the alpha-beta interdimer interactions that form the self-association site of the tetramer and in the alpha-beta intradimer interactions at the head of the heterodimer.
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Affiliation(s)
- K E Sahr
- Department of Biomedical Research, St. Elizabeth's Hospital of Boston, Tufts University School of Medicine, Massachusetts 02135
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36
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MESH Headings
- Africa/epidemiology
- Africa/ethnology
- Anemia, Hemolytic/etiology
- Anion Exchange Protein 1, Erythrocyte/deficiency
- Anion Exchange Protein 1, Erythrocyte/genetics
- Ankyrins
- Asia, Southeastern/epidemiology
- Blood Proteins/deficiency
- Blood Proteins/genetics
- Cytoskeletal Proteins
- Elliptocytosis, Hereditary/classification
- Elliptocytosis, Hereditary/epidemiology
- Elliptocytosis, Hereditary/genetics
- Erythrocyte Membrane/chemistry
- Erythrocyte Membrane/ultrastructure
- Erythrocytes, Abnormal/ultrastructure
- Gene Frequency
- Genes, Dominant
- Genes, Recessive
- Genetic Predisposition to Disease
- Humans
- Malaria/complications
- Malaria/epidemiology
- Membrane Proteins/deficiency
- Membrane Proteins/genetics
- Neuropeptides
- Prevalence
- Selection, Genetic
- Spectrin/genetics
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37
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Coetzer TL, Sahr K, Prchal J, Blacklock H, Peterson L, Koler R, Doyle J, Manaster J, Palek J. Four different mutations in codon 28 of alpha spectrin are associated with structurally and functionally abnormal spectrin alpha I/74 in hereditary elliptocytosis. J Clin Invest 1991; 88:743-9. [PMID: 1679439 PMCID: PMC295451 DOI: 10.1172/jci115371] [Citation(s) in RCA: 45] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
Abstract
Hereditary elliptocytosis (HE) Sp alpha I/74 is a disorder associated with defective spectrin (Sp) heterodimer self-association and an abnormal tryptic cleavage of the 80-kD alpha I domain of Sp resulting in increased amounts of a 74-kD peptide. The molecular basis of this disorder is heterogeneous and mutations in codons 28, 46, 48, and 49 (codons 22, 40, 42, and 43 in the previous nomenclature which did not include the six NH2-terminal amino acids) have been reported. In this study we present data on seven unrelated HE Sp alpha I/74 kindred from diverse racial backgrounds in whom we identified four different mutations all occurring in exon 2 of alpha Sp at codon 28. Utilizing the polymerase chain reaction we established a CGT----CTT; Arg----Leu 28 mutation in one kindred of Arab/Druze origin. In two unrelated white kindred of English/European origin the substitution is CGT----AGT; Arg----Ser 28 and in two apparently unrelated white kindred from New Zealand, the mutation is CGT----TGT; Arg----Cys 28. Finally, in one American black kindred and in a black kindred from Ghana the mutation involves CGT----CAT; Arg----His 28. Allele specific oligonucleotide hybridization confirmed that the probands are heterozygous for the respective mutant alleles. All four point mutations abolished an Aha II restriction enzyme site which allowed verification of linkage of the mutation with HE Sp alpha I/74. Our results imply that codon 28 of alpha Sp is a "hot spot" for mutations and also indicate that Arg 28 is critical for the conformational stability and functional self association of Sp heterodimers.
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Affiliation(s)
- T L Coetzer
- Department of Biomedical Research, St. Elizabeth's Hospital of Boston, Tufts University School of Medicine, Boston, Massachusetts 02135
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38
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Jarolim P, Palek J, Coetzer TL, Lawler J, Velez-Garcia E, Fradera J, Charles A, Jacob HS, Moake JL. Severe hemolysis and red cell fragmentation caused by the combination of a spectrin mutation with a thrombotic microangiopathy. Am J Hematol 1989; 32:50-6. [PMID: 2667341 DOI: 10.1002/ajh.2830320110] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
Two patients are described who presented with severe hemolysis and erythrocyte fragmentation. One patient had renal allograft rejection and disseminated intravascular coagulation, and the other had thrombotic thrombocytopenia purpura. The severity of hemolysis and the red cell abnormalities were considerably more profound than usually seen in patients with thrombotic microangiopathies. After evaluation of blood smears prepared before the onset of the disease and biochemical characterization of proteins of the red blood cell skeleton, a mutation of the skeletal protein spectrin, designated Sp alpha l/65, was identified. In the heterozygous form, this mutation manifests as mild, often asymptomatic, hereditary elliptocytosis. We conclude that in these two patients with thrombotic microangiopathy, the intrinsic red cell membrane instability resulting from the underlying skeletal defect aggravated the mechanical red cell fragmentation, producing morphological features similar to the severe hemolytic form of hereditary elliptocytosis or hereditary pyropoikilocytosis.
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Affiliation(s)
- P Jarolim
- Department of Biomedical Research, St. Elizabeth's Hospital of Boston, MA 02135
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39
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Lawler J, Coetzer TL, Mankad VN, Moore RB, Prchal JT, Palek J. Spectrin-alpha I/61: a new structural variant of alpha-spectrin in a double-heterozygous form of hereditary pyropoikilocytosis. Blood 1988; 72:1412-5. [PMID: 3167214] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023] Open
Abstract
Recent biochemical studies have led to the identification of abnormal spectrins in the erythrocytes of patients with hereditary pyropoikilocytosis (HPP) and hereditary elliptocytosis (HE). In this report we describe the biochemical characterization of the erythrocytes from a proband with severe HPP who is doubly heterozygous for two mutant spectrins (Sp): Sp alpha I/74 and a new, previously undetected, mutant of alpha-spectrin designated Sp alpha I/61. The proband's erythrocytes are unstable when exposed to 45 degrees C, and her membrane skeletons exhibit instability to shear stress. The content of spectrin in the proband's erythrocyte membranes is decreased to 75% of control values. The amount of spectrin dimers in crude 4 degrees C spectrin extracts is increased (58%) as compared with control values (6% +/- 4%). Limited tryptic digestion reveals a marked decrease in the normal 80,000-dalton alpha I domain, an increase in the 74,000-dalton fragment that is characteristic of Sp alpha I/74, and an increase in a series of new fragments of 61,000, 55,000, 21,000, and 16,000 daltons. Both parents are asymptomatic, but they have increased amounts of spectrin dimers (17% to 25%). Limited tryptic digestion of the father's spectrin demonstrates the presence of a previously identified abnormal spectrin (Sp alpha I/74) that is characterized by a decrease in content of the 80,000-dalton peptide and an increase in concentration of the 74,000-dalton peptide. The mother's spectrin digests show a decrease in the amount of 80,000-dalton peptide and the formation of new peptides of 61,000, 55,000, 21,000, and 16,000 daltons. The data indicate that this severe form of HPP is due to the inheritance of two distinct abnormal spectrins, Sp alpha I/74 and a new spectrin mutant, Sp alpha I/61.
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Affiliation(s)
- J Lawler
- Department of Biomedical Research, St Elizabeth's Hospital, Boston, MA 02135
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40
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Coetzer TL, Lawler J, Liu SC, Prchal JT, Gualtieri RJ, Brain MC, Dacie JV, Palek J. Partial ankyrin and spectrin deficiency in severe, atypical hereditary spherocytosis. N Engl J Med 1988; 318:230-4. [PMID: 2961992 DOI: 10.1056/nejm198801283180407] [Citation(s) in RCA: 57] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Affiliation(s)
- T L Coetzer
- Department of Biomedical Research, St. Elizabeth's Hospital, Boston, MA 02135
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41
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Prchal JT, Morley BJ, Yoon SH, Coetzer TL, Palek J, Conboy JG, Kan YW. Isolation and characterization of cDNA clones for human erythrocyte beta-spectrin. Proc Natl Acad Sci U S A 1987; 84:7468-72. [PMID: 3478706 PMCID: PMC299317 DOI: 10.1073/pnas.84.21.7468] [Citation(s) in RCA: 29] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023] Open
Abstract
Spectrin is an important structural component of the membrane skeleton that underlies and supports the erythrocyte plasma membrane. It is composed of nonidentical alpha (Mr 240,000) and beta (Mr 220,000) subunits, each of which contains multiple homologous 106-amino acid segments. We report here the isolation and characterization of a human erythroid-specific beta-spectrin cDNA clone that encodes parts of the beta-9 through beta-12 repeat segments. This cDNA was used as a hybridization probe to assign the beta-spectrin gene to human chromosome 14 and to begin molecular analysis of the gene and its mRNA transcripts. RNA transfer blot analysis showed that the reticulocyte beta-spectrin mRNA is 7.8 kilobases in length. Southern blot analysis of genomic DNA revealed the presence of restriction fragment length polymorphisms (RFLPs) within the beta-spectrin gene locus. The isolation of human spectrin cDNA probes and the identification of closely linked RFLPs will facilitate analysis of mutant spectrin genes causing congenital hemolytic anemias associated with quantitative and qualitative spectrin abnormalities.
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Affiliation(s)
- J T Prchal
- Department of Opthalmology, University of Alabama, Birmingham 35294
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42
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Coetzer TL, Palek J. Partial spectrin deficiency in hereditary pyropoikilocytosis. Blood 1986; 67:919-24. [PMID: 3955236] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
Hereditary pyropoikilocytosis (HPP) is a severe hemolytic anemia in which an instability of the red cell membrane skeleton has been correlated with structural and functional defects of spectrin. We now report that 13 unrelated HPP subjects have approximately 30% less spectrin than normal as evidenced by a decreased spectrin/band 3 ratio. We also examine the role of spectrin degradation as an underlying cause of this partial spectrin deficiency. Our studies demonstrate that the reduced spectrin content of HPP red cells remains constant during in vivo aging of the cells in the peripheral blood, as well as during in vitro incubation. Furthermore, immunoblotting experiments using an affinity-purified antispectrin antibody indicate that there is no loss of spectrin during membrane preparation and also that neither whole HPP red cells nor ghosts nor cytosol contains any abnormal spectrin degradation products. These data suggest that spectrin is not degraded and that it is stable on the membrane of the circulating HPP red cell. In contrast, however, incubation of free spectrin with a lysate of nucleated erythroid precursor cells indicates that HPP alpha I/46 spectrin, but not HPP alpha I/74 spectrin, is more susceptible to proteolytic degradation than a control. These data imply that the decreased spectrin content of HPP is not due to a single defect but that a more complex mechanism is involved. In HPP Sp alpha I/46 subjects, an increased proteolytic degradation in bone marrow erythroid precursors of cytosolic spectrin, prior to its assembly on the membrane, could contribute toward the partial spectrin deficiency.
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43
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Lawler J, Coetzer TL, Palek J, Jacob HS, Luban N. Sp alpha I/65: a new variant of the alpha subunit of spectrin in hereditary elliptocytosis. Blood 1985; 66:706-9. [PMID: 4027386] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
Two molecular defects involving the spectrin heterodimer (SpD) contact site of the alpha chain (the alpha I domain) were previously identified using limited tryptic digestion followed by two-dimensional isoelectric focusing/sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Both are characterized by atypical peptide maps which reveal a marked decrease of the 80,000-dalton alpha I domain and a formation of new major peptides of either 74,000 (Sp alpha I/74) or 46,000 (Sp alpha I/46) daltons. We now report a third variant of the spectrin alpha chain, designated Sp alpha I/65, in three unrelated black families. In all three probands, the percentage of SpD in the low ionic strength (O degrees C) membrane extracts was increased to 19% to 32%. One- and two-dimensional electrophoretic separations of limited tryptic digests of spectrin from all three probands revealed a decrease of the alpha I domain of spectrin and the concomitant appearance of peptides at 65,000 daltons and isoelectric points ranging from 5.2 to 5.3. The abnormal 65,000-dalton peptides could be stained with an antiserum which had been raised against the alpha I domain, indicating that it was derived from the alpha I domain.
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44
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Zail SS, Coetzer TL. Defective binding of spectrin to ankyrin in a kindred with recessively inherited hereditary elliptocytosis. J Clin Invest 1984; 74:753-62. [PMID: 6236232 PMCID: PMC425229 DOI: 10.1172/jci111491] [Citation(s) in RCA: 27] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023] Open
Abstract
The interaction of spectrin with spectrin-depleted inside-out membrane vesicles was studied in a kindred with an atypical variant of hereditary elliptocytosis inherited in a recessive manner. The probands are characterized by prominent elliptocytosis, decreased erythrocyte thermal stability, an altered limited tryptic peptide pattern of spectrin digested at low ionic strength, and defective spectrin dimer-dimer association. The parents are normal. The spectrin/band 3 ratio determined by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) of isolated membranes of the probands was decreased to approximately 70% of control values, and total erythrocyte spectrin content in one proband was also decreased on SDS-PAGE. When a monospecific antispectrin antibody was used, a faintly labeled fragment of molecular weight approximately 28,000 was detected on immunoblots of whole cell lysates of one proband and a control, but could not account for the decreased erythrocyte spectrin content of the proband on SDS-PAGE. Binding and competitive inhibition studies revealed an alteration in the spectrin-ankyrin interaction due to an abnormality of spectrin in the probands. No defect was found in the mother; the father's spectrin showed decreased binding affinity, although it was not so severe as in the probands. Separation of bound and unbound spectrin dimers from one proband and subsequent conversion to tetramers showed that the self-association defect was detectable only on the bound subpopulation of her spectrin. These findings demonstrate a hitherto undescribed functional abnormality of spectrin in this kindred which could result in decreased stability of the membrane skeleton and contribute to the elliptocytic shape of these erythrocytes.
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Abstract
The membranes of erythrocytes undergoing metabolic depletion or an influx of calcium undergo several changes in structure and function. In erythrocytes incubated without substrate we find extensive cross-linking of membrane proteins by disulphide bonding occurring after 24--48 h, involving all major membrane proteins as well as haemoglobin. Aggregates of mol wt 40 x 10(6) or greater are formed. These changes are partially reversible by repletion with adenosine. Rapid introduction of calcium (intracellular concentrations approximately 0.6 mM) into metabolically replete erythrocytes with the ionophore A23187 results in transglutaminase-dependent cross-linking of membrane proteins. Cellular calcium concentrations of approximately 0.3 mM have no cross-linking effect. Cells undergoing metabolic depletion show a progressive loss of transglutaminase activity to undetectable levels at 12 h, so that influx of calcium into such cells cannot cause cross-linking by a transglutaminase-mediated reaction. These studies suggest that the metabolic state of the cell and the rate and degree of calcium influx into erythrocytes are critical factors in determining the type of membrane protein cross-linkage.
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46
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Balinsky JB, Coetzer TL, Mattheyse FJ. The effect of thyroxine and hypertonic environment on the enzymes of the urea cycle in Xenopus laevis. Comp Biochem Physiol B 1972; 43:83-95. [PMID: 4653167 DOI: 10.1016/0305-0491(72)90204-0] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
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