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Chandrasekaran FP, Vishal A, Arora U, Kumar S U, George C PD, Nelson EJR. Molecular dynamics simulations corroborate recombinant expression studies carried out on three αIIb β-propeller mutations reported in Indian Glanzmann thrombasthenia patients. J Cell Biochem 2023. [PMID: 37210732 DOI: 10.1002/jcb.30423] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2023] [Revised: 04/27/2023] [Accepted: 05/04/2023] [Indexed: 05/23/2023]
Abstract
Mutations in the αIIb β-propeller domain have long been known to disrupt heterodimerization and intracellular trafficking of αIIbβ3 complexes leading to diminished surface expression and/or function, resulting in Glanzmann thrombasthenia. Our previous study on three β-propeller mutations, namely G128S, S287L, and G357S, showed variable defects in protein transport correlated with the patient's clinical phenotypes. Pulse-chase experiments revealed differences in αIIbβ3 complex maturation among the three mutations. Hence, the current study aims to correlate conformational changes caused by each one of them. Evolutionary conservation analysis, stability analysis, and molecular dynamics simulations of the three mutant structures were carried out. Stability analysis revealed that, while G128S and G357S mutations destabilized the β-propeller structure, S287L retained the stability. Wild-type and mutant β-propeller structures, when subjected to molecular dynamics simulations, confirmed that G128S and G357S were both destabilizing in nature when compared with the wild-type and S287L based on several parameters studied, like RMSD, RMSF, Rg, FEL, PCA, secondary structure, and hydrogen bonds. In our previous study, we demonstrated that mutant S287L αIIbβ3 complexes were more stable than the wild-type αIIbβ3 complexes, as evidenced in pulse-chase experiments. These findings corroborate variable intracellular fates of mutant αIIbβ3 complexes as a result of these β-propeller mutations.
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Affiliation(s)
- Finola Priyadharshini Chandrasekaran
- Gene Therapy Laboratory, Department of Integrative Biology, School of Bio Sciences and Technology, Vellore Institute of Technology, Vellore, India
| | - Adarsh Vishal
- Gene Therapy Laboratory, Department of Integrative Biology, School of Bio Sciences and Technology, Vellore Institute of Technology, Vellore, India
| | - Udita Arora
- Gene Therapy Laboratory, Department of Integrative Biology, School of Bio Sciences and Technology, Vellore Institute of Technology, Vellore, India
| | - Udhaya Kumar S
- Laboratory of Integrative Genomics, Vellore Institute of Technology, Vellore, India
| | - Priya Doss George C
- Laboratory of Integrative Genomics, Vellore Institute of Technology, Vellore, India
| | - Everette Jacob Remington Nelson
- Gene Therapy Laboratory, Department of Integrative Biology, School of Bio Sciences and Technology, Vellore Institute of Technology, Vellore, India
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Ittiwut R, Suchartlikitwong P, Kittikalayawong Y, Ittiwut C, Prasopsanti K, Sosothikul D, Shotelersuk V, Suphapeetiporn K. Novel mutations in Thai patients with glanzmann thrombasthenia. Eur J Haematol 2017; 99:520-524. [PMID: 28888044 DOI: 10.1111/ejh.12965] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 09/03/2017] [Indexed: 11/29/2022]
Abstract
OBJECTIVES Glanzmann thrombasthenia (GT) is an autosomal recessive platelet disorder, caused by defects of the platelet integrin αIIbβ3 (GPIIb/IIIa) resulting from pathogenic mutations in either ITGA2B or ITGB3. It is characterized by spontaneous mucocutaneous bleeding. The molecular features of GT in Thailand have not been identified. This study aimed to determine the clinical and molecular features of unrelated Thai patients with GT. METHODS Four patients with clinically suspected GT were recruited at the Division of Pediatric Hematology/Oncology, King Chulalongkorn Memorial Hospital. The diagnosis was based on clinical and hematological parameters as well as genetic analysis. Whole exome sequencing (WES) was performed in all cases. RESULTS Of the four patients studied, the median age at first suspicion of GT was 2.5 years. All presented with severe bleeding symptoms (WHO bleeding scale 3). Flow cytometry to assess the surface GPIIb/IIIa complex showed reduced expression. By WES, we successfully identified seven mutant alleles in ITGA2B. One alteration, the c.2915dup (p.Leu973Alafs*63), was detected in two unrelated families. One patient was homozygous for the c.617T>A (p.Val206Asp). Of the five different mutations, three have never been previously described. These include a missense, c.617T>A (p.Val206Asp), a deletion, c.1524_1533del (p.Gln508Hisfs*3), and a nonsense, c.2344C>T (p.Arg782Ter). CONCLUSION This study reported three novel mutations expanding the genotypic spectrum of ITGA2B causing GT.
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Affiliation(s)
- Rungnapa Ittiwut
- Center of Excellence for Medical Genetics, Department of Pediatrics, Faculty of Medicine, Chulalongkorn University, Bangkok, Thailand.,Excellence Center for Medical Genetics, King Chulalongkorn Memorial Hospital, The Thai Red Cross Society, Bangkok, Thailand
| | | | - Yaowaree Kittikalayawong
- Division of Pediatric Hematology/Oncology, Department of Pediatrics, Faculty of Medicine, Chulalongkorn University, Bangkok, Thailand
| | - Chupong Ittiwut
- Center of Excellence for Medical Genetics, Department of Pediatrics, Faculty of Medicine, Chulalongkorn University, Bangkok, Thailand.,Excellence Center for Medical Genetics, King Chulalongkorn Memorial Hospital, The Thai Red Cross Society, Bangkok, Thailand
| | - Karan Prasopsanti
- Excellence Center for Medical Genetics, King Chulalongkorn Memorial Hospital, The Thai Red Cross Society, Bangkok, Thailand
| | - Darintr Sosothikul
- Division of Pediatric Hematology/Oncology, Department of Pediatrics, Faculty of Medicine, Chulalongkorn University, Bangkok, Thailand
| | - Vorasuk Shotelersuk
- Center of Excellence for Medical Genetics, Department of Pediatrics, Faculty of Medicine, Chulalongkorn University, Bangkok, Thailand.,Excellence Center for Medical Genetics, King Chulalongkorn Memorial Hospital, The Thai Red Cross Society, Bangkok, Thailand
| | - Kanya Suphapeetiporn
- Center of Excellence for Medical Genetics, Department of Pediatrics, Faculty of Medicine, Chulalongkorn University, Bangkok, Thailand.,Excellence Center for Medical Genetics, King Chulalongkorn Memorial Hospital, The Thai Red Cross Society, Bangkok, Thailand
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Nurden AT, Pillois X, Fiore M, Alessi MC, Bonduel M, Dreyfus M, Goudemand J, Gruel Y, Benabdallah-Guerida S, Latger-Cannard V, Négrier C, Nugent D, Oiron RD, Rand ML, Sié P, Trossaert M, Alberio L, Martins N, Sirvain-Trukniewicz P, Couloux A, Canault M, Fronthroth JP, Fretigny M, Nurden P, Heilig R, Vinciguerra C. Expanding the Mutation Spectrum Affecting αIIbβ3 Integrin in Glanzmann Thrombasthenia: Screening of the ITGA2B and ITGB3 Genes in a Large International Cohort. Hum Mutat 2016; 36:548-61. [PMID: 25728920 DOI: 10.1002/humu.22776] [Citation(s) in RCA: 59] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2014] [Accepted: 02/18/2015] [Indexed: 12/19/2022]
Abstract
We report the largest international study on Glanzmann thrombasthenia (GT), an inherited bleeding disorder where defects of the ITGA2B and ITGB3 genes cause quantitative or qualitative defects of the αIIbβ3 integrin, a key mediator of platelet aggregation. Sequencing of the coding regions and splice sites of both genes in members of 76 affected families identified 78 genetic variants (55 novel) suspected to cause GT. Four large deletions or duplications were found by quantitative real-time PCR. Families with mutations in either gene were indistinguishable in terms of bleeding severity that varied even among siblings. Families were grouped into type I and the rarer type II or variant forms with residual αIIbβ3 expression. Variant forms helped identify genes encoding proteins mediating integrin activation. Splicing defects and stop codons were common for both ITGA2B and ITGB3 and essentially led to a reduced or absent αIIbβ3 expression; included was a heterozygous c.1440-13_c.1440-1del in intron 14 of ITGA2B causing exon skipping in seven unrelated families. Molecular modeling revealed how many missense mutations induced subtle changes in αIIb and β3 domain structure across both subunits, thereby interfering with integrin maturation and/or function. Our study extends knowledge of GT and the pathophysiology of an integrin.
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Affiliation(s)
- Alan T Nurden
- Institut de Rhythmologie et de Modélisation Cardiaque, Plateforme Technologique d'Innovation Biomédicale, Hôpital Xavier Arnozan, Pessac, France
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4
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Mansour W, Hauschner H, Seligsohn U, Rosenberg N, Einav Y. Natural and artificial mutations in αIIb integrin lead to a structural deformation of a calcium-binding site. Protein J 2014; 33:474-83. [PMID: 25216802 DOI: 10.1007/s10930-014-9579-5] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
Abstract
The platelet integrin αIIbβ3 is widely accepted as a structural and a functional model of the broad integrin protein family. The four calcium-binding sites in the αIIb subunit contribute to biogenesis and stability of the protein. Mansour et al. (J Thromb Haemost 9:192-200, 2011) showed that the natural Asn2Asp mutation causing Glanzmann thrombasthenia, prevented surface expression of αIIbβ3, whereas the artificial Asn2Gln mutation only decreased its level. Molecular dynamics simulations and EDTA chelation assay were used here to explore the mechanism of these structural deformations. We show a considerable expansion of the calcium-binding site 3 in Asn2Asp mutation, whereas the Asn2Gln toggles between normal and expanded conformations. The αIIbβ3 surface expression level correlates to the relative spending time in the expanded conformation. By a comparison to other calcium-binding sites of αIIb and of other α integrins we show that the size of a calcium-binding loop is conserved. EDTA chelation assay shows a sensitivity to calcium removal, which correlates with the reduction in αIIbβ3 surface expression and with the calcium binding site expansion, thus verifying the simulation data. Here we indicate that Asn2 mutation affects a calcium-binding site 3 of αIIb, which structural deformation is proposed to deprive calcium binding and interfere with an integrin intracellular trafficking and its surface expression.
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Affiliation(s)
- Wissam Mansour
- The Amalia Biron Research Institute of Thrombosis and Haemostasis, Chaim Sheba Medical Center, 52621, Tel-Hashomer, Israel
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Nurden AT, Pillois X, Wilcox DA. Glanzmann thrombasthenia: state of the art and future directions. Semin Thromb Hemost 2013; 39:642-55. [PMID: 23929305 DOI: 10.1055/s-0033-1353393] [Citation(s) in RCA: 50] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Glanzmann thrombasthenia (GT) is the principal inherited disease of platelets and the most commonly encountered disorder of an integrin. GT is characterized by spontaneous mucocutaneous bleeding and an exaggerated response to trauma caused by platelets that fail to aggregate when stimulated by physiologic agonists. GT is caused by quantitative or qualitative deficiencies of αIIbβ3, an integrin coded by the ITGA2B and ITGB3 genes and which by binding fibrinogen and other adhesive proteins joins platelets together in the aggregate. Widespread genotyping has revealed that mutations spread across both genes, yet the reason for the extensive variation in both the severity and intensity of bleeding between affected individuals remains poorly understood. Furthermore, although genetic defects of ITGB3 affect other tissues with β3 present as αvβ3 (the vitronectin receptor), the bleeding phenotype continues to dominate. Here, we look in detail at mutations that affect (i) the β-propeller region of the αIIb head domain and (ii) the membrane proximal disulfide-rich epidermal growth factor (EGF) domains of β3 and which often result in spontaneous integrin activation. We also examine deep vein thrombosis as an unexpected complication of GT and look at curative procedures for the diseases, including allogeneic stem cell transfer and the potential for gene therapy.
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Affiliation(s)
- Alan T Nurden
- Plateforme Technologique et d'Innovation Biomédicale, Hôpital Xavier Arnozan, Pessac, France.
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Pillois X, Fiore M, Heilig R, Pico M, Nurden AT. A novel amino acid substitution of integrin αIIb in Glanzmann thrombasthenia confirms that the N-terminal region of the receptor plays a role in maintaining β-propeller structure. Platelets 2012; 24:77-80. [DOI: 10.3109/09537104.2012.665278] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
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7
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Mansour W, Einav Y, Hauschner H, Koren A, Seligsohn U, Rosenberg N. An αIIb mutation in patients with Glanzmann thrombasthenia located in the N-terminus of blade 1 of the β-propeller (Asn2Asp) disrupts a calcium binding site in blade 6. J Thromb Haemost 2011; 9:192-200. [PMID: 21029361 DOI: 10.1111/j.1538-7836.2010.04087.x] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
BACKGROUND Studies of Glanzmann thrombasthenia (GT)-causing mutations has generated invaluable information on the formation and function of integrin αIIbβ(3). OBJECTIVE To characterize the mutation in four siblings of an Israeli Arab family affected by GT, and to analyze the relationships between the mutant protein structure and its function using artificial mutations. METHODS AND RESULTS Sequencing disclosed a new A97G transversion in the αIIb gene predicting Asn2Asp substitution at blade 1 of the β-propeller. Alignment with other integrin α subunits revealed that Asn2 is highly conserved. No surface expression of αIIbβ(3) was found in patients' platelets and baby hamster kidney (BHK) cells transfected with mutated αIIb and WT β(3). Although the αIIbβ(3) was formed, the mutation impaired its intracellular trafficking. Molecular dynamics simulations and modeling of the αIIbβ(3) crystal indicated that the Asn2Asp mutation disrupts a hydrogen bond between Asn2 and Leu366 of a calcium binding domain in blade 6, thereby impairing calcium binding that is essential for intracellular trafficking of αIIbβ(3). Substitution of Asn2 to uncharged Ala or Gln partially decreased αIIbβ(3) surface expression, while substitution by negatively or positively charged residues completely abolished surface expression. Unlike αIIbβ(3), αVβ(3) harboring the Asn2Asp mutation was surface expressed by transfected BHK cells, which is consistent with the known lower sensitivity of αVβ(3) to calcium chelation compared with αIIbβ(3). CONCLUSION The new GT causing mutation highlights the importance of calcium binding domains in the β-propeller for intracellular trafficking of αIIbβ(3). The mechanism by which the mutation exerts its deleterious effect was elucidated by molecular dynamics.
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Affiliation(s)
- W Mansour
- Amalia Biron Research Institute of Thrombosis and Hemostasis, Chaim Sheba Medical Center, Tel Hashomer and Sackler Faculty of Medicine, Tel-Aviv University, Tel-Aviv, Israel.
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Landau M, Rosenberg N. Molecular insight into human platelet antigens: structural and evolutionary conservation analyses offer new perspective to immunogenic disorders. Transfusion 2010; 51:558-69. [PMID: 20804530 PMCID: PMC3084503 DOI: 10.1111/j.1537-2995.2010.02862.x] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Abstract
BACKGROUND Human platelet antigens (HPAs) are polymorphisms in platelet membrane glycoproteins (GPs) that can stimulate production of alloantibodies once exposed to foreign platelets (PLTs) with different HPAs. These antibodies can cause neonatal alloimmune thrombocytopenia, posttransfusion purpura, and PLT transfusion refractoriness. Most HPAs are localized on the main PLT receptors: 1) integrin αIIbβ3, known as the fibrinogen receptor; 2) the GPIb-IX-V complex that functions as the receptor for von Willebrand factor; and 3) integrin α2β1, which functions as the collagen receptor. STUDY DESIGN AND METHODS We analyzed the structural location and the evolutionary conservation of the residues associated with the HPAs to characterize the features that induce immunologic responses but do not cause inherited diseases. RESULTS We found that all HPAs reside in positions located on the protein surface, apart from the ligand-binding site, and are evolutionary variable. CONCLUSION Disease-causing mutations often reside in highly conserved and buried positions. In contrast, the HPAs affect residues on the protein surface that were not conserved throughout evolution; this explains their naive effect on the protein function. Nonetheless, the HPAs involve substitutions of solvent-exposed positions that lead to altered interfaces on the surface of the protein and might present epitopes foreign to the immune system.
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Affiliation(s)
- Meytal Landau
- Amalia Biron Research Institute of Thrombosis and Hemostasis, Chaim Sheba Medical Center, Tel-Hashomer, Israel
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9
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A unique interaction between alphaIIb and beta3 in the head region is essential for outside-in signaling-related functions of alphaIIbbeta3 integrin. Blood 2010; 115:4542-50. [PMID: 20308600 DOI: 10.1182/blood-2009-10-251066] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023] Open
Abstract
The main interface of the 2 subunits of platelet integrin alphaIIbbeta3 comprises the beta-propeller domain of alphaIIb and the betaA domain of beta3. In the center of the beta-propeller, several aromatic residues interact by cation-pi and hydrophobic bonds with Arg261 of betaA. In this study, we substituted alphaIIb-Trp110 or beta3-Arg261 by residues abundant in other alpha or beta subunits at corresponding locations and expressed them in baby hamster kidney cells along with normal beta3 or alphaIIb, respectively. These mutant cells displayed normal surface expression and fibrinogen binding but grossly impaired outside-in signaling-related functions: adhesion to immobilized fibrinogen, cell spreading, focal adhesion kinase phosphorylation, clot retraction, and reduced alphaIIbbeta3 stability in EDTA (ethylenediaminetetraacetic acid). Expression of mutants with substitutions of Arg261 in beta3 by alanine or lysine with normal alphav yielded normal surface expression of alphavbeta3 and soluble fibrinogen binding as well as normal outside-in signaling-related functions, contrasting findings for alphaIIbbeta3. Structural analysis of alphaIIbbeta3 and alphavbeta3 revealed that alphavbeta3 has several strong interactions between alphav and beta3 subunits that are missing in alphaIIbbeta3. Together, these findings indicate that the interaction between Trp110 of alphaIIb and Arg261 of beta3 is critical for alphaIIbbeta3 integrity and outside-in signaling-related functions.
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Gupta V, Alonso JL, Sugimori T, Essafi M, Issafi M, Xiong JP, Arnaout MA. Role of the beta-subunit arginine/lysine finger in integrin heterodimer formation and function. THE JOURNAL OF IMMUNOLOGY 2008; 180:1713-8. [PMID: 18209068 DOI: 10.4049/jimmunol.180.3.1713] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Formation of the integrin alphabeta heterodimer is essential for cell surface expression and function. At the core of the alphabeta interface is a conserved Arg/Lys "finger" from the beta-subunit that inserts into a cup-like "cage" formed of two layers of aromatic residues in the alpha-subunit. We evaluated the role of this residue in heterodimer formation in an alphaA-lacking and an alphaA-containing integrin alphaVbeta3 and alphaMbeta2 (CD11b/CD18), respectively. Arg261 of beta3 was mutated to Ala or Glu; the corresponding Lys252 of beta2 was mutated to Ala, Arg, Glu, Asp, or Phe; and the effects on heterodimer formation in each integrin examined by ELISA and immunoprecipitation in HEK 293 cells cotransfected with plasmids encoding the alpha- and beta-subunits. The Arg261Glu (but not Arg261Ala) substitution significantly impaired cell surface expression and heterodimer formation of alphaVbeta3. Although Lys252Arg, and to a lesser extent Lys252Ala, were well tolerated, each of the remaining substitutions markedly reduced cell surface expression and heterodimer formation of CD11b/CD18. Lys252Arg and Lys252Ala integrin heterodimers displayed a significant increase in binding to the physiologic ligand iC3b. These data demonstrate an important role of the Arg/Lys finger in formation of a stable integrin heterodimer, and suggest that subtle changes at this residue affect the activation state of the integrin.
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Affiliation(s)
- Vineet Gupta
- Division of Nephrology, Leukocyte Biology and Inflammation Program, Structural Biology Program, Massachusetts General Hospital and Harvard Medical School, 149 13th Street, Charlestown, MA 02129, USA
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Nelson EJR, Nair SC, Peretz H, Coller BS, Seligsohn U, Chandy M, Srivastava A. Diversity of Glanzmann thrombasthenia in southern India: 10 novel mutations identified among 15 unrelated patients. J Thromb Haemost 2006; 4:1730-7. [PMID: 16879215 DOI: 10.1111/j.1538-7836.2006.02066.x] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
BACKGROUND Glanzmann thrombasthenia (GT) is a congenital bleeding disorder caused by either a lack or dysfunction of the platelet integrin alphaIIbbeta3. OBJECTIVES To determine the molecular basis of GT in patients from southern India. PATIENTS Fifteen unrelated patients whose diagnosis was consistent with GT were evaluated. RESULTS Platelet surface expression of alphaIIbbeta3 was < 10%, 10%-50%, and > 50% of controls in five, nine, and one patient(s), respectively. Immunoblotting of the platelet lysates showed no alphaIIb in 14 patients, and no beta3 in 10 patients, although severely reduced in four patients. Platelet fibrinogen was undetectable in 13 patients, and severely reduced in one patient. One patient showed normal surface alphaIIbbeta3 expression, and normal alphaIIb, beta3 and fibrinogen levels in the lysate. Ten novel candidate disease-causing mutations were identified in 11 patients. The missense mutations included Gly128Ser, Ser287Leu, Gly357Ser, Arg520Trp, Leu799Arg in alphaIIb, and Cys575Gly in beta3. We have already shown that Gly128Ser, Ser287Leu, and Gly357Ser mutations variably affect alphaIIbbeta3 surface expression. The Cys575Gly mutation may disrupt the disulphide link with Cys586 to cause the GT phenotype. The molecular pathology of the other missense mutations is not clear. Two nonsense mutations, Trp-16Stop and Glu715Stop in alphaIIb, and a 7-bp deletion (330-336TCCCCAG) in beta3 are predicted to result in truncated proteins. An IVS15(-1)G --> A mutation in alphaIIb induced a cryptic splice site as confirmed by reverse transcription-polymerase chain reaction (RT-PCR) analysis. Thirteen polymorphisms were also identified (five in alphaIIb and eight in beta3), among which five were novel. CONCLUSIONS While identifying a significant number of novel mutations causing GT, this study confirms the genetic heterogeneity of the disorder in southern India.
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Affiliation(s)
- E J R Nelson
- Department of Hematology, Christtian Medical College, Vellore, India
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12
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Peretz H, Rosenberg N, Landau M, Usher S, Nelson EJR, Mor-Cohen R, French DL, Mitchell BW, Nair SC, Chandy M, Coller BS, Srivastava A, Seligsohn U. Molecular diversity of Glanzmann thrombasthenia in southern India: new insights into mRNA splicing and structure-function correlations ofαIIbβ3 integrin (ITGA2B, ITGB3). Hum Mutat 2006; 27:359-69. [PMID: 16463284 DOI: 10.1002/humu.20304] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
The molecular basis of Glanzmann thrombasthenia (GT) was studied in 40 families from southern India. Of 23 identified mutations (13 in the alphaIIb (ITGA2B) gene and 10 in the beta3 (ITGB3) gene), 20 were novel and three were described previously. Three mutations in the beta3 gene-p.Leu143Trp (Leu117Trp), p.Tyr307Stop (Tyr281Stop), and p.Arg119Gln (Arg93Gln)-were detected in 12, three, and two families, respectively, with definite founder effects observed for the first two mutations. Alternative splicing was predicted in silico for the normal variant and a missense variant of the beta3 gene, and for 10/11 frameshift or nonsense mutations in alphaIIb or beta3. The prediction was confirmed experimentally for a c.2898_2902dupCCCCT mutation in exon 28 of the alphaIIb gene that induced exon skipping. Seven out of nine missense mutations substituted highly conserved amino acids buried in the proteins' cores, predicting structural abnormalities. Among these, a beta3 substitution, p.Cys39Gly (Cys13Gly) was found to cause intracellular degradation of the beta3 subunit, in contrast to previous findings that mutations at Cys435, the partner of Cys13 in a disulfide bond, cause constitutive activation of alphaIIbbeta3. The two patients with a beta3 Arg93Gln mutation had normal clot retraction, consistent with a recent finding that this substitution is associated with normal surface expression of alphaIIbbeta3. In conclusion, this study demonstrates that a variety of mutations account for GT in southern Indian patients, provides new insights into mRNA splicing, and highlights the role of specific amino acids in structure-function correlations of alphaIIbbeta3.
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Affiliation(s)
- Hava Peretz
- Clinical Biochemistry Laboratory, Sourasky Medical Center, Tel Aviv, Israel.
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13
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Nelson EJ, Li J, Mitchell WB, Chandy M, Srivastava A, Coller BS. Three novel beta-propeller mutations causing Glanzmann thrombasthenia result in production of normally stable pro-alphaIIb, but variably impaired progression of pro-alphaIIbbeta3 from endoplasmic reticulum to Golgi. J Thromb Haemost 2005; 3:2773-83. [PMID: 16359515 PMCID: PMC1569905 DOI: 10.1111/j.1538-7836.2005.01593.x] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
BACKGROUND Glanzmann thrombasthenia (GT) is an autosomal recessive bleeding disorder characterized by lack of platelet aggregation in response to most physiological agonists and caused by either a lack or dysfunction of the platelet integrin alpha(IIb)beta3 (glycoprotein IIb/IIIa). OBJECTIVES To determine the molecular basis of GT and characterize the mutations by in vitro expression studies. PATIENTS We studied three unrelated patients from southern India whose diagnosis was consistent with GT. RESULTS Immunoprecipitation of the cell lysates and immunoblotting showed no detectable mature alpha(IIb) in the G128S mutant, in contrast to 6% and 33% of the normal amount of mature alpha(IIb) in the S287L and G357S mutants, respectively. Pulse-chase analysis demonstrated pro-alpha(IIb) in the mutants comparable with the normal pro-alpha(IIb), but no conversion to mature alpha(IIb) in the G128S mutant, and only trace conversion to mature alpha(IIb) in the S287L and G357S mutants. The disappearance of pro-alpha(IIb) in the three mutants was similar to that in cells expressing normal alpha(IIb)beta3 or alpha(IIb) only. All three mutants demonstrated pro-alpha(IIb)beta3 complexes and co-localized with an ER marker by immunofluorescence. The G128S mutant showed no co-localization with a Golgi marker, and the other two mutants showed minimal and moderate co-localization with the Golgi marker. CONCLUSIONS These three beta-propeller mutations do not affect the production of pro-alpha(IIb), its ability to complex with beta3, or its stability, but do cause variable defects in transport of pro-alpha(IIb)beta3 complexes from the endoplasmic reticulum to the Golgi.
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Affiliation(s)
- E. J. Nelson
- From the Laboratory of Blood and Vascular Biology, The Rockefeller University, New York, NY 10021, USA and the
| | - J. Li
- From the Laboratory of Blood and Vascular Biology, The Rockefeller University, New York, NY 10021, USA and the
| | - W. B. Mitchell
- From the Laboratory of Blood and Vascular Biology, The Rockefeller University, New York, NY 10021, USA and the
| | - M. Chandy
- Department of Hematology, Christian Medical College, Vellore, TN 632004, INDIA
| | - A. Srivastava
- Department of Hematology, Christian Medical College, Vellore, TN 632004, INDIA
| | - B. S. Coller
- From the Laboratory of Blood and Vascular Biology, The Rockefeller University, New York, NY 10021, USA and the
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ROSENBERG N, HAUSCHNER H, PERETZ H, MOR-COHEN R, LANDAU M, SHENKMAN B, KENET G, COLLER BS, AWIDI AA, SELIGSOHN U. A 13-bp deletion in alpha(IIb) gene is a founder mutation that predominates in Palestinian-Arab patients with Glanzmann thrombasthenia. J Thromb Haemost 2005; 3:2764-72. [PMID: 16359514 PMCID: PMC1557653 DOI: 10.1111/j.1538-7836.2005.01618.x] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Glanzmann thrombasthenia (GT) is a rare autosomal recessive bleeding disorder caused by lack or dysfunction of alpha(IIb)beta3 in platelets. GT is relatively frequent in highly inbred populations. We previously identified a 13-bp deletion in the alpha(IIb) gene that causes in-frame deletion of six amino acids in three Palestinian GT patients. In this study, we determined the molecular basis of GT in all known Palestinian patients, examined whether Jordanian patients harbor the same mutations, analyzed whether there is a founder effect for the 13-bp deletion, and determined the mechanism by which the 13-bp deletion abolishes alpha(IIb)beta3 surface expression. Of 11 unrelated Palestinian patients, eight were homozygous for the 13-bp deletion that displayed common ancestry by haplotype analysis, and was estimated to have occurred 300-600 years ago. Expression studies in baby hamster kidney cells showed that substitution of Cys107 or Trp110 located within the deletion caused defective alpha(IIb)beta3 maturation. Substitution of Trp110, but not of Cys107, prevented fibrinogen binding. The other Palestinian patients harbored three novel mutations: G2374 deletion in alpha(IIb) gene, TT1616-7 deletion in beta3 gene, and IVS14: -3C --> G in beta3 gene. The latter mutation caused cryptic splicing predicting an extended cytoplasmic tail of beta3 and was expressed as dysfunctional alpha(IIb)beta(3). None of 15 unrelated Jordanian patients carried any of the described mutations.
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Affiliation(s)
- N. ROSENBERG
- Amalia Biron Research Institute of Thrombosis and Hemostasis, The Chaim Sheba Medical Center, Tel-Hashomer and Sackler Faculty of Medicine, Tel-Aviv University, Tel-Aviv, Israel
| | - H. HAUSCHNER
- Amalia Biron Research Institute of Thrombosis and Hemostasis, The Chaim Sheba Medical Center, Tel-Hashomer and Sackler Faculty of Medicine, Tel-Aviv University, Tel-Aviv, Israel
| | - H. PERETZ
- Clinical Biochemistry Laboratory, Sourasky Medical Center, Tel Aviv, Israel
| | - R. MOR-COHEN
- Amalia Biron Research Institute of Thrombosis and Hemostasis, The Chaim Sheba Medical Center, Tel-Hashomer and Sackler Faculty of Medicine, Tel-Aviv University, Tel-Aviv, Israel
| | - M. LANDAU
- Department of Biochemistry, George S. Wise Faculty of Life Sciences, Tel-Aviv University, Tel-Aviv, Israel
| | - B. SHENKMAN
- Amalia Biron Research Institute of Thrombosis and Hemostasis, The Chaim Sheba Medical Center, Tel-Hashomer and Sackler Faculty of Medicine, Tel-Aviv University, Tel-Aviv, Israel
| | - G. KENET
- Amalia Biron Research Institute of Thrombosis and Hemostasis, The Chaim Sheba Medical Center, Tel-Hashomer and Sackler Faculty of Medicine, Tel-Aviv University, Tel-Aviv, Israel
| | - B. S. COLLER
- Laboratory of Blood and Vascular Biology, Rockefeller University New York, NY, USA; and
| | | | - U. SELIGSOHN
- Amalia Biron Research Institute of Thrombosis and Hemostasis, The Chaim Sheba Medical Center, Tel-Hashomer and Sackler Faculty of Medicine, Tel-Aviv University, Tel-Aviv, Israel
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