basset and human Thrombasthenia thrombopathia

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basset and human Thrombasthenia thrombopathia

Postby malernee » Mon Sep 25, 2006 9:38 am

Vet Pathol 38:249-260 (2001)
© 2001 American College of Veterinary Pathologists

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ANIMAL MODELS

Clinical, Biochemical, and Molecular Aspects of Glanzmann's Thrombasthenia in Humans and Dogs
M. K. Boudreaux and D. L. Lipscomb
Department of Pathobiology, College of Veterinary Medicine, Auburn University, Auburn, AL


Abstract
Top
Abstract
The {alpha}IIbß3...
Glanzmann's...
Glanzmann's...
Conclusions
References


Glanzmann's thrombasthenia (GT) is an inherited, intrinsic platelet function defect that involves the platelet glycoprotein complex IIb–IIIa, also known as the fibrinogen receptor and the integrin IIbß3. The defect was originally described by Dr. Glanzmann in humans in 1918 as a bleeding disorder that differed clinically from other known coagulopathies. Over the decades that followed, researchers determined the biochemical and molecular basis for the disease in humans. Otterhounds with thrombasthenic thrombopathia, described in the 1960s, were the only animal model that closely resembled the disease described in humans until 1996. At that time, a Great Pyrenees dog was identified with unequivocal clinical and biochemical features of Type I GT. The cDNA encoding for glycoproteins IIb and IIIa were sequenced in normal dogs in 1999, allowing for identification of specific mutations causing Type I GT in both Otterhounds and Great Pyrenees dogs. Knowing the molecular basis for Type I GT in dogs as well as the cDNA sequences in normal dogs should enhance the understanding of structure/function relationships of the IIbß3 integrin and provide an excellent animal model for studies aimed at correction of GT in humans. The following review focuses on the structure and function of this platelet receptor and reviews the molecular, biochemical, and clinical aspects of Glanzmann's thrombasthenia in humans and dogs.



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Glanzmann's thrombasthenia (GT) is an inherited, intrinsic platelet function defect involving the glycoprotein complex IIb–IIIa, also known as the IIbß3 integrin. The defect was originally described by a Swiss physician, Edward Glanzmann,60 in 1918; however, the biochemical basis for the defect was not understood until the mid-1970s.98,102,105 The first genetic mutation causing GT in humans was described in 1990.18 Bleeding was described as being primarily mucosal, with epistaxis being the most common clinical manifestation. Bleeding patterns were consistent with laboratory findings that revealed normal platelet numbers but lack of platelet aggregation in response to all agonists and severely impaired clot retraction. Coagulation screening tests and von Willebrand factor antigen levels were also normal, ruling out other causes for the bleeding disorder. Bleeding tendencies in affected individuals ranged from mild to severe, with males and females being equally affected, suggesting an autosomal inheritance pattern. Although early reports of the defect were almost entirely within consanguineous populations, today the defect has been described in numerous ethnic groups, many without known consanguineous relationships.49 In veterinary medicine, Otterhounds were the first breed described with a platelet defect that closely resembled that described in human GT.38 Subsequently, platelet defects were described in Basset hounds and Great Pyrenees dogs that suggested these defects were also possibly GT.15,28 Molecular studies confirmed that thrombasthenic thrombopathia of Otterhounds and the platelet defect in Great Pyrenees were identical to Type I GT described in human beings (Table 1).16 Molecular studies of the Basset hound defect, however, did not confirm the existence of GT.



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Table 1. Comparison of canine von Willebrand's disease (vWD) with canine and human Type I Glanzmann's thrombasthenia (GT) and human variant GT.*




Studies of GT at the molecular and biochemical level have led to a better understanding of the structure–function relationships of integrins in general, but especially IIbß3. Expanded capabilities in terms of diagnostics, drug development, treatment, and disease prevention in areas ranging from venomology110,112 to cardiology106 have occurred as a result of such studies. Comparative information on this integrin across species lines should further enhance our knowledge, particularly at the molecular level, which will aid in prediction of amino acid arrangements and protein structure, phenotype, and immunologic cross-reactivities. In cardiovascular medicine, much of the focus in recent years in humans has been on inhibiting platelet reactivity postmyocardial infarction. Many promising agents have been developed that target the IIbß3 integrin specifically35,106,118 based on information known at the biochemical and molecular level in human platelets about this integrin. Most of these agents were evaluated for their efficacy in animal models before they were used in humans, yet very little comparative data were available at the molecular level in dogs, the animal model usually used. Perhaps having more information at the molecular level in animal models will shed light on why some of these agents, although seemingly efficacious and safe in dogs, were not found to be so in humans. Recently, researchers have suggested that certain polymorphisms within the ß3 subunit protein predispose human beings to heart disease.22,131,133 The most controversial report by Weiss in 1996 identified the PlA2 allele as a significant risk factor for acute myocardial infarction. Since that time, numerous studies and reports have been presented, with approximately 50% of those reports supporting the original observation and another 50% refuting the observation.22 Knowing phenotypes and genotypes in other species may help to clarify this and other areas of controversy. The sequences for the genes encoding for the IIb and ß3 subunits have been determined in mice.31,126 ß3 knockout mice have been developed that have clinical and laboratory features characteristic of GT, including mucosal hemorrhage, poor clot retraction, and reduced platelet aggregation. However, their use as a model for GT in humans is in question with the recent finding that these mice develop osteosclerosis, a syndrome not described in humans with GT resulting from ß3 subunit defects.91 IIb knockout mice have also been recently developed by introducing the herpes virus thymidine kinase gene into the IIb locus.129 These mice have characteristic features of GT, including reduced alpha granular content of fibrinogen, further verifying the necessity of an intact IIbß3 integrin for the uptake and storage of fibrinogen. Although these mice may prove to be good models for GT, their size is a limiting factor, especially for experiments requiring repeated blood sampling. Recently, the cDNA sequences for the genes encoding the IIb and ß3 subunits were determined in the dog. In addition, the molecular basis for GT was determined in Great Pyrenees and Otterhounds. This information should help investigators continue to obtain a better understanding of the IIbß3 integrin, with continued progress in disease recognition, prevention, treatment, control, and potentially cure.

The IIbß3 Integrin
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Abstract
The {alpha}IIbß3...
Glanzmann's...
Glanzmann's...
Conclusions
References


The IIbß3 glycoprotein, an extensively studied integrin, is associated primarily with megakaryocytes and their progeny, platelets.106,121 IIbß3 is an abundant and functionally significant integrin expressed on platelets.121 This receptor binds fibrinogen with highest affinity but also binds other Arginine-Glycine-Aspartic acid (RGD)-containing molecules such as fibronectin, von Willebrand factor, and vitronectin.10,56,107,116,121 The IIbß3 integrin is required for platelet aggregation,52 clot retraction,34 and platelet spreading along vascular matrices122 but also plays an important role in platelet transmembrane signaling32,33,57,65,69,85,121 and in the uptake of fibrinogen for storage in platelet -granules.66 Platelets possess 40,000 to 80,000 molecules of IIbß3 per cell,25,130 with most of these receptors being distributed on the membrane surface71 and the remainder being bound to the inner membrane of -granules134 and the internal surface-connected canalicular system.138 Upon platelet activation, the occult IIbß3 molecules are translocated to the platelet surface when the -granules fuse with the platelet membrane and the canalicular system evaginates during the shape change response.24,96 Platelet activation also initiates cytoplasmic signals that induce IIbß3 clustering and triggers conformational changes in IIbß3 extracellular domains (inside-out signaling) to enhance ligand binding.24,123,124 The receptor clustering is mediated by cytoskeletal reorganization and structural changes in proteins that are directly or indirectly linked to the cytoplasmic tails of IIbß3.47,84,121 Although precise details regarding IIbß3 and platelet inside-out signaling remain unclear, circumstantial evidence suggests that the mechanism is similar to that of other integrins. Platelets contain RhoA, FAK, and Src proteins that reportedly mediate integrin clustering, stress fiber formation, and focal adhesion assembly in other cells.32,33,47,94,121 Phosphatidylinositol-kinase (PI-K) converts phosphatidylinositides to 4,5-bisphosphate (PIP2) and 3,4,5-triphosphate (PIP3).75,121 Exposure of platelets to thrombin stimulates PI-K activation and results in IIbß3 activation, but PI-K inhibitors, when added to thrombin-treated platelets, decrease the ligand-binding affinity of IIbß3 and promote platelet disaggregation.81,121,140

IIbß3-ligand association triggers receptor clustering on the platelet membrane, and the simultaneous binding of dimeric fibrinogen molecules to these receptor clusters mediates platelet aggregation.24 Receptor-ligand binding also stimulates interactions between the IIbß3 cytoplasmic domains and the platelet cytoskeleton (outside-in signaling) and initiates clot retraction.24 Although details are unclear, fibrinogen-binding and agonist stimulation initiate phosphorylation (activation) of Src, Syk, and FA kinases that activate other proteins and lead to further cytoskeleton reorganization.24,121

The IIbß3 receptor was one of the first integrins identified,98 purified,73 cloned,90,113 and sequenced45 and was also the first integrin to be expressed in recombinant form.59,100 In 1974, Nurden and Caen identified an abnormal migration pattern when platelet-associated glycoproteins from three thrombasthenic patients were processed and electrophoresed and compared to patterns obtained from normal platelets. Two of these glycoproteins, which were undetectable on platelets from the thrombasthenic patients, were eventually designated GPIIb and GPIIIa.98 In the early 1980s, Jennings and Phillips purified glycoproteins IIb and IIIa from platelets and characterized the GPIIb-IIIa complex as being calcium dependent.73

Expression of IIbß3 on the platelet surface requires the presence of both subunits; defects in either IIb or ß3 usually result in absence of the IIbß3 complex.100 Maintenance of IIbß3 stability is calcium dependent and fibrinogen binding is optimized when all four IIb calcium-binding sites are occupied.63,135 When the IIbß3 complex is expressed on the platelet surface, the amino termini of the and ß subunits interact with each other to form a globular structure that contains the ligand-binding domain.132

The IIb subunit is synthesized as a single precursor protein that forms a dimeric complex with the ß3 subunit while associated with the rough endoplasmic reticulum (ER).100 The IIbß3 complex is transported to the golgi apparatus where the IIb subunit is cleaved into a light chain of 137 amino acids and a heavy chain of 871 amino acids that remain linked by a disulfide bond.24,44,78,79,114 The mature IIb subunit possesses seven functional domains: extracellular,24,78,79 transmembrane,24,48 cytoplasmic,24,48,64 and four extracellular calcium-binding domains.24,63,68,108 The light chain makes up the IIb cytoplasmic and transmembrane domains and a small portion of the extracellular domain.77,97 The majority of the IIb extracellular domain, including the four calcium-binding domains, is associated with the heavy chain77,97 (Fig. 1).





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Fig. 1 Structure of IIbß3 complex. The IIb light chain, heavy chain, and four calcium-binding domains (Ca++) are designated. The amino termini are indicated by N and the carboxy termini are labeled COOH. Disufide bonds are indicated by (-S-S-). Diagram is modified from Albelda et al.1 and Ginsberg et al.59




The genes that encode the IIb and ß3 subunits have been mapped to the q21–23 band of chromosome 17 in humans.19,125 The IIb gene, from genomic DNA, consists of approximately 17.2 kilobases (kb) and contains 30 exons, designated 1 through 30, that range in size from 45 basepairs (bp) to 249 bp.68,108 Each of the four calcium-binding domains consists of 12 amino acids that are encoded by gene segments of two adjacent exons.108 The first calcium-binding domain (closest to the amino terminus) is encoded by exons 8 and 9; the second calcium-binding domain is encoded by exons 11 and 12; the third is encoded by exons 12 and 13; and the fourth is encoded by exons 13 and 14108 (Fig. 2). The site of posttranslational cleavage into a light chain and a heavy chain is encoded near the 3' end of exon 26108 (Fig. 2). The IIb gene has 5' and 3' untranslated regions (UTR) that are encoded by exons 1 and 30, respectively, and exon 1 encodes a 31 amino acid signal peptide68,108 (Fig. 2).




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Fig. 2 Relationship between IIb coding region and exon distribution. Exon 1 encodes the 5' untranslated region (UTR and the signal peptide (SP). The four calcium-binding domains (Ca++) are encoded by segments of exons 8, 9, 11, 12, 13, and 14. The cleavage site (CS) is encoded near the 3' end of exon 26. Exon 30 encodes a 3' UTR. Diagram has been condensed as indicated by (//) and is modified from Heidenreich et al.68




The ß3 subunit is a single polypeptide 762 amino acids in length45 and has five functional domains: cytoplasmic,139 transmembrane,45 extracellular,48 and RGD (ligand-binding)39,41 domains and a region associated with calcium-dependent stabilization of the IIbß3 fibrinogen-binding pocket.80,83,120 In addition, the ß3 subunit possesses five extracellular cysteine-rich regions that facilitate disulfide bond formation and confer a globular conformation to the subunit26,97 (Fig. 1). The ß3 gene of humans is 63 kb in length and is composed of 14 exons, designated A through N, and range in length from 87 bp to 430 bp.82,137,141 The ß3 sequence, obtained from cDNA, is 2.3 kb in length.31 Exons I and J encode four cysteine-rich regions that form loop structures via disulfide linkage with segments encoded by exons C, D, and E83 (Figs. 1, 3). Exon A encodes a 26 amino acid signal peptide.45 Protein segments important for ligand binding, the RGD-binding region and the segment associated with stabilization of the fibrinogen-binding pocket, are encoded by exons C and D, respectively29,39,41,80,83 (Fig. 3).




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Fig. 3 Relationship betweend the ß3 coding region and exon distribution. Exon A encodes the signal peptide (SP). Four cysteine-rich regions (C) are encoded by exons I and J. The RGD-binding region (RGD) is encoded by a segment of exon C and a segment associated with stabilization of the fibrinogen binding pocket (F) is encoded by exon D. Diagram is modified from Lanza et al.82 and is not drawn to scale.




The nucleotide sequence of canine platelet-derived cDNA was compared with the sequence previously established for IIb of humans.88 Canine IIb, from platelet-derived cDNA, was nine nucleotides shorter in length than the human gene due to the lack of nucleotides corresponding to positions 2401 through 2403 (exon 24 in humans) in canine cDNA and because the termination codon in canine IIb was located six nucleotides 5' to that of humans (exon 30). The nucleotides flanking the missing codon in exon 24 are conserved in dogs and humans, and the negatively charged character of the carboxy-terminus is maintained by the deduced sequence of six consecutive glutamic acid residues in canine IIb. The nucleotide sequence of full-length IIb obtained from canine platelet-derived cDNA shared 86% similarity with that of humans. The nucleotide sequences of IIb segments that encode functional domains in humans, including the four calcium-binding domains, shared 78% similarity when the canine sequence was compared with that of humans. The deduced amino acid sequence of canine IIb shared 100% similarity with the segment that encodes the second calcium-binding domain of IIb in humans.
The nucleotide sequence of canine ß3 from platelet-derived cDNA was compared with that of humans and mice.86 The sequence of full-length canine ß3 shared 92 and 87% similarity with the sequences previously reported for humans and mice, respectively. The nucleotide sequence of canine ß3 shared at least 85% similarity with the segments that encode functional domains in ß3 of humans and mice, and the region associated with calcium-dependent stability was identical for all three species when deduced amino acid sequences were compared.

The observed sequence differences may contribute to species variations in receptor–ligand interactions and may partially explain differences in reactivity of platelets for differenct species. Gene sequence conservation between species implies structural and functional importance, and ß3 regions of complete and near-complete similarity across species may represent ß3-specific domains.31

In recent years, analysis of natural and artificial mutations affecting IIbß3 have provided valuable information concerning integrin structure–function relationships.24,51 Subunit synthesis and assembly of the IIbß3 complex have been studied extensively. Posttranslational cleavage of IIb into light and heavy chains is required for expression of the IIbß3 complex on the platelet surface.78,79,142 Maintenance of the structural integrity of IIb calcium-binding sites dictates heterodimer conformation and expression on the platelet surface.8,11,135 Structural stability and surface expression of IIbß3 requires the association of all three peptides, the IIb light and heavy chains and ß3.27,48,78,79,100 Maintenance of IIb and ß3 disulfide bridges is required for proper folding and subunit stability.30,95 The IIbß3 RGD-binding sites (amino acid residues 109–171 and 211–222 of ß3) were defined when investigators performed chemical cross-linking studies and identified mutations that disrupted ligand binding and resulted in the bleeding disorder Glanzmann's thrombasthenia.5,29,39–43,89,120


Glanzmann's Thrombasthenia—Humans
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Abstract
The {alpha}IIbß3...
Glanzmann's...
Glanzmann's...
Conclusions
References


In 1918, Dr. Edward Glanzmann, a Swiss physician, used the (translated) terms "hereditary hemorrhagic thrombasthenia" to describe the bleeding diatheses of his patients.54,60 Dr. Glanzmann attributed his patients' bleeding disorders to defective platelets because of abnormal in vitro clot retraction despite normal platelet quantitation.54,60 Later, other laboratory manifestations were reported, including prolonged bleeding time and the observation that platelets appeared isolated rather than having pseudopodia and being clumped (aggregated) when blood smears of affected individuals were examined microscopically.17,46,54,93 In the 1960s, investigators characterized Glanzmann's thrombasthenia (GT) as a platelet function defect resulting in abnormal aggregation due to an unidentified platelet membrane abnormality.54,67,142 In the mid-1970s, Nurden and Caen, as well as Phillips et al., demonstrated that platelets from thrombasthenic patients possessed decreased amounts of glycoproteins IIb and IIIa.98,103,105 When other scientists showed that platelets from thrombasthenic individuals were unable to bind fibrinogen, it was suggested that the platelet glycoprotein complex IIb–IIIa may serve as the fibrinogen receptor.9,55 Thrombasthenia was proposed to have an autosomal-recessive mode of inheritance due to the following observations: males and females were affected in equal numbers, parents of thrombasthenic patients were asymptomatic, and 25% of the cases were associated with consanguinity.23,54,67 Also, variability in the degree of clinical bleeding was reported; some patients presented with severe and potentially fatal hemorrhage while others demonstrated only mild bruising.54

Glanzmann's thrombasthenia was first described at the molecular level in humans in 1990.20 Currently, GT is widespread and has been recently reported in Japanese,2,3,127 African American,21 Indian,76 mixed Caucasian,8 Chinese,61,62 French Gypsy,117 Iranian,101 and Algerian92 populations. Although the overall incidence of GT is low, the reported frequency of GT approaches that of Von Willebrand's disease and hemophilia in consanguineous populations.113 A website database has been established with mutation information on reported human cases of Glanzmann's thrombasthenia at http://med.mssm.edu/glanzmanndb.

The occurrence of hemorrhagic episodes during infancy and early childhood usually leads to diagnosis of GT before the age of 5 years; however, symptoms typically diminish as affected individuals approach adulthood.53 Hemorrhage associated with GT occurs primarily in mucocutaneous tissues.19 Observed bleeding patterns include epistaxis (most common), bruising, gingival hemorrhage, gastrointestinal hemorrhage, hematuria, menorrhagia, and hemarthrosis.53 Spontaneous hemorrhage is uncommon in GT, but the most serious bleeding episodes occur after trauma or are exaggerated versions of normal physiologic bleeding; e.g., spontaneous shedding of deciduous teeth and minor surgical procedures, such as circumcision, commonly result in severe hemorrhage.4,53,119 In affected women, menstruation and parturition represent particular risks for severe hemorrhage.53

The severity of bleeding associated with GT is unpredictable, even when comparing thrombasthenic siblings of similar age.53 Glanzmann's thrombasthenia is best managed with supportive medical care (blood transfusions and/or platelet transfusions) and by minimizing anticipated risks of hemorrhage with the use of platelet transfusions.53 The most common complication is iron deficiency anemia secondary to chronic blood loss, and iron therapy (oral and injectable) is frequently required.53 The development of platelet isoantibodies is associated with platelet transfusions.53

The first classification scheme for GT, proposed by Caen, was based on platelet -granule fibrinogen content and degree of clot retraction; however, current classification also includes IIbß3 quantitation.19,23,98,103,104 To date, 59 different molecular defects resulting in GT have been identified in 48 kindred.7,49 Nineteen of these cases have been compound heterozygotes (different mutation inherited from each parent) while 29 have been homozygous.

Type I GT represents the majority of reported cases and is characterized by severe deficiency (<5% of normal concentration) of immunologically detectable IIbß3, inability of activated platelets to bind fibrinogen, markedly reduced fibrinogen within platelet -granules, and failure of platelets to aggregate or sustain clot retraction.53,104 Platelets from patients with Type I GT due to a mutation in the gene encoding for IIb often display increased levels of the vitronectin receptor.37 This phenomenon is thought to be due to increased availability of ß3 for binding to v subunits. Detection of normal to increased ß3 on the surface of Type I GT platelets lends support to the existence of an IIb gene defect.37 Gene defects that have resulted in Type I GT include deletions and insertions that caused alternative splicing, nonsense mutations that resulted in premature truncation of either IIb or ß3, as well as single nucleotide changes that resulted in single amino acid changes in areas critical for normal subunit stability and processing.7,50,102 Mutations between and near the calcium-binding domain encoding regions of IIb will result in Type I GT if the mutation results in an overall change in charge.2,8,109,115,136 These mutations do not impair pro-IIb synthesis or pro-IIbß3 complex assembly; however, the complexes are not transported from the ER to the Golgi.

Type II GT represents 14% of the reported cases. Platelets of individuals in this group possess 10 to 20% of the normal quantity of IIbß3 and show minimal fibrinogen binding, minimal aggregation, and abnormal clot retraction.53,104 Type II GT cases most commonly arise when defects are present in the gene encoding for ß3.50 Of particular susceptibility are areas of the gene encoding for the RGD binding domain (amino acids 109–171). Within this domain is a MIDAS-like structure, DXSXS, involving amino acids 119 through 123. This domain is highly conserved among all beta subunits. Another critical domain is defined by the amino acids 211–222. Both of these sites are important for ligand recognition/binding and for cation binding.128 Mutations in the RGD-binding domain region usually result in either Type II GT or variant GT.58,72,99 One case of Type I GT was due to a mutation involving the change of a leucine to a tryptophan at position 117.6 Site-directed mutagenesis studies indicated that this mutation resulted in malfolded IIbß3 heterodimers, which could not be transported to the platelet surface. Type II GT as a result of mutations in the gene encoding for IIb have also been reported.135 Mutations between and near the calcium-binding domain encoding regions that do not result in an overall change in charge result in Type II GT due to reduced and slower transport of the IIbß3 complexes to the surface. IIbß3 complex assembly and transport from the ER to the Golgi are not impaired with these defects.115

Variant GT represents 8% of reported cases.53,104 Platelets of these individuals possess 50 to 100% of the normal quantity of IIbß3 but demonstrate absent or minimal fibrinogen binding and aggregation, and results of clot retraction tests vary from normal to absent.53,104 Whereas Type I and Type II GT are due to quantitative deficiency of IIbß3, variant GT is due to a qualitative defect of IIbß3.53,104 As with Type II GT, variant GT is usually a result of a mutation in the gene encoding for ß3. The CAM variant,58 involving an amino acid change from aspartic acid to tyrosine at position 119 (within the highly conserved MIDAS-like motif) was one of the first cases of variant GT described at the molecular level. The Strasbourg variant,83 a mutation resulting from a change in amino acid arginine to tryptophan at position 214, illustrated the importance of the RGD-binding region between amino acids 211 and 222. Aspartic acid 217 is thought to play a major role in cation coordination. Change to amino acid tryptophan would be predicted to destabilize the cation coordination mediated at this position.128


Glanzmann's Thrombasthenia—Canine
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The {alpha}IIbß3...
Glanzmann's...
Glanzmann's...
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Otterhounds

Thrombasthenic thrombopathia of Otterhounds was originally described in 1967.38 Affected dogs exhibited mucosal bleeding and prolonged bleeding times that were aggravated by stress or surgery. The defect was described as being a combination of Bernard Soulier's disease (reduced/absent levels of platelet glycoprotein complexes Ib–IX) and Glanzmann's thrombasthenia. Thirty to 80% of platelets from affected dogs were described as being bizarre and giant, a characteristic typical of platelets from patients with Bernard Soulier's disease. Platelet glycoprotein studies, however, indicated that glycoproteins II and III were reduced while glycoprotein I was increased.111 Platelet aggregation in response to all agonists was markedly reduced and clot retraction was minimal to absent. The defect was aggressively pursued and largely eliminated from the breed by the 1970s. However, in the late 1980s and early 1990s, descendents of originally described affected dogs were identifed with platelet dysfunction. Platelet aggregation responses to ADP, collagen, and thrombin were markedly reduced to absent, and intraplatelet fibrinogen and clot retraction were markedly reduced, as had been described in the original population. Platelet glycoprotein studies indicated that affected platelets had reduced to absent amounts of glycoprotein subunits IIb and IIIa, but changes in other glycoproteins were not seen. Flow cytometry studies did indicate the presence of glycoprotein IIIa on the surface of affected platelets, suggesting that the defect may involve the gene encoding for glycoprotein IIb. Platelet morphology and platelet size were normal, unlike what had been described in the original population.

Platelet-derived cDNA encoding for glycoproteins IIb and IIIa were sequenced in known normal, obligate carrier, and affected Otterhounds in 1999. A single nucleotide change G1193 C (G1100 C if leader sequence is not included) was detected in exon 12 of the gene encoding for glycoprotein IIb in the affected dog. The obligate carrier Otterhound was heterozygous for this change and the normal Otterhound was unchanged compared with normal dogs.12,13,16 This nucleotide change would result in the substitution of a histidine for an aspartic acid at position 398 (367) within the third calcium binding domain of glycoprotein IIb. Based on studies in humans, such a change would be expected to destabilize the glycoprotein IIb–IIIa complex, resulting in lack of expression of the complex on the platelet surface.

Great Pyrenees

The test case, first described in 1996, presented with a history of gingival bleeding and chronic epistaxis since the age of 6 months.15 Platelet numbers ranged from 150,000/µl to 250,000/µl and were not low enough to account for the protracted mucosal bleeding seen. Von Willebrand factor antigen levels were normal. Platelet aggregation responses to ADP, collagen, PAF, and thrombin were characterized by shape change with no aggregation. Clot retraction was absent. Platelet membrane surface labeling with I125 did not demonstrate detectable levels of glycoproteins IIb or IIIa; however, other glycoproteins were present in normal amounts. Flow cytometry studies were able to detect small amounts of platelet glycoprotein IIIa, suggesting a defect in the gene encoding for IIb.

Segments of platelet-derived cDNA from the affected dog encoding for glycoproteins IIb and IIIa were amplified and sequenced.86,88 Affected dog cDNA contained a 14 base pair repeat in exon 13 and defective splicing of the intron between exons 13 and 14. The insertion disrupted the cDNA segment that encodes the fourth calcium-binding domain, caused a shift in the reading frame, and resulted in a premature termination codon after 42 aberrant codons. The truncation of the IIb protein would be expected to completely eliminate the transmembrane and cytoplasmic domains and a large portion of the extracellular domain, including the fourth calcium-binding domain, which is important for intracellular processing of IIbß3 and transport of the complex to the platelet surface. Based on studies in humans, although assembly of the glycoprotein complex probably occurs, transport to the platelet surface is likely impaired.

Since this test case was described, a young male Great Pyrenees from the Chicago area was identified with a history of excessive bleeding during tooth eruption.87 Platelet numbers and von Willebrand factor antigen levels were normal. The veterinarian was not in close proximity to a laboratory that could perform platelet function studies on the dog. Genetic analysis revealed a defect identical to that described in the test case. Gene studies on the parents and siblings revealed that the parents were carriers. Three siblings were also carriers and one was normal. One puppy died at birth and could not be tested. Great Pyrenees dogs related and unrelated to this family group have since been identified as carriers for this defect in Oklahoma, Indiana, and Illinois.

Basset Hounds

Basset Hound thrombopathia was first described in 1979.74 Affected Basset Hounds experienced epistaxis, gingival bleeding, and petechiation on mucous membranes and skin. Platelet counts, von Willebrand factor analysis, and coagulation screening tests were normal while bleeding times were prolonged, tending to focus the cause of the bleeding disorder at the platelet function level. Platelet aggregation responses to most agonists was minimal; however, platelets did aggregate in response to thrombin with a characteristic lag phase.28 Platelet -granule fibrinogen content was determined to be normal as were membrane glycoproteins IIb and IIIa. Fibrinogen binding by platelets, however, was impaired.28 These findings suggested that Basset Hound thrombopathia may be a form of variant Glanzmann's thrombasthenia. However, sequence analysis of platelet-derived cDNA collected from affected Basset Hounds was identical to normal dogs for the segments encoding for glycoproteins IIb and IIIa (Boudreaux, unpublished findings). Although Basset Hound thrombopathia appears to be a qualitative defect involving the glycoprotein IIb–IIIa complex, the defect cannot be placed in the variant GT classification if the same rules used in humans are applied to dogs. Studies have indicated that the failure of the glycoprotein IIb–IIIa complex to be expressed properly in response to most agonists may be due to a defect in the metabolism of cAMP.14 Thus far, platelet defects in humans involving signal transduction-related causes have not been classified as variant GT.


Conclusions
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The {alpha}IIbß3...
Glanzmann's...
Glanzmann's...
Conclusions
References


Extensive study of the pathophysiologic mechanisms of GT have led to important discoveries regarding normal platelet function; e.g., IIbß3 was identified as the platelet receptor for fibrinogen.98 Subsequent investigation of IIbß3 helped define the integrin family of adhesion molecules and also helped characterize receptor-ligand structure–function relationships.70 Recent molecular-level studies of GT have increased our knowledge of the genes that encode IIbß3 and have also led to the identification of specific genetic mutations that are responsible for the thrombasthenic phenotype.50

Determination of the nucleotide sequence of IIb and ß3 for different species may provide valuable information regarding IIbß3 structure–function relationships and should promote comparative studies that will increase the understanding of variation in integrin-ligand interactions. Knowledge of IIb organization for different species may also improve the understanding of regulation of tissue-specific gene expression. Comparative analysis of IIb and ß3 for different species may be useful in studies of bleeding disorders that affect humans and veterinary species. Information gained may help establish the canine as a good model for gene therapy of Glanzmann's thrombasthenia and for evaluating IIbß3-inhibitors as antithrombotic agents.



References
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Glanzmann's...
Glanzmann's...
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Albelda SM, Buck CA: Integrins and other cell adhesion molecules. FASEB J 4:2868-2880, 1990[Abstract]
Ambo H, Kamata T, Handa M, Kawai Y Oda A, Murata M, Takada Y, Ikeda Y: Novel point mutations in the alphaIIb subunit (Phe289Ser, Glu324Lys and Gln747Pro) causing thrombasthenic phenotypes in four Japanese patients. Br J Haematol 102:829-840, 1998[Medline]
Ambo H, Kamata T, Handa M, Taki M, Kuwajima M, Kawai Y, Oda A, Murata M, Takada Y, Watanabe K, Ikeda Y: Three novel integrin beta 3 subunit missense mutations (H280P, C560F, and G579S) in thrombasthenia, including one (H280P) prevalent in Japanese patients. Biochem Biophys Res Commun 251:763-768, 1998[CrossRef][Medline]
Awidi AS: Increased incidence of Glanzmann's thrombasthenia in Jordan compared with Scandinavia. Scand J Haematol 30:218-222, 1983[Medline]
Bajt ML, Ginsberg MH, Frelinger AL, III Berndt MC, Loftus JC: A spontaneous mutation of integrin IIbß3 (platelet glycoprotein IIb-IIIa) helps define a ligand binding site. J Biol Chem 267:3789-3794, 1992[Abstract/Free Full Text]
Basani RB, Brown DL, Vilaire G, Bennett JS, Poncz M: A Leu117Trp mutation within the RGD-peptide cross-linking region of ß3 results in Glanzmann thrombasthenia by preventing IIbß3 export to the platelet surface. Blood 90:3082-3088, 1997[Abstract/Free Full Text]
Basani RB, French DL, Vilaire G, Brown DL, Chen G, Coller BS, Derrick JM, Gartner TK, Bennett JS, Poncz M: A naturally occurring mutation near the amino terminus of IIb defines a new region involved in ligand binding to IIbß3. Blood 95:(1) 180-188, 2000[Abstract/Free Full Text]
Basani RB, Vilaire G, Shattil SJ, Kolodziej MA, Bennett JS, Poncz M: Glanzmann thrombasthenia due to a two amino acid deletion in the fourth calcium-binding domain of IIb: demonstration of the importance of calcium-binding domains on the conformation of IIbß3. Blood 88:167-173, 1996[Abstract/Free Full Text]
Bennett JS: The platelet-fibrinogen interaction. In: Platelet Membrane Glycoproteins, George JN, Nurden AT, and Phillips DR, p 193, Plenum Press, New York 1985
Bennett JS, Vilaire G: Exposure of platelet fibrinogen receptors by ADP and epinephrine. J Clin Invest 64:1393-1401, 1979[Medline]
Bennett JS, Vilaire G, Poncz M: Effect of mutations in the calcium binding domains of platelet glycoprotein IIb on the expression of the glycoprotein IIb–IIIa complex. Thromb Haemost 69:1022, 1993 [abstract]
Boudreaux MK, Catalfamo JL: Evaluation of the genes encoding for GP complex IIb–IIIa in Otterhounds with thrombasthenic thrombopathia. Vet Pathol 36:(5) 483, 1999 [abstract]
Boudreaux MK, Catalfamo JL: The molecular and genetic basis for Glanzmann's thrombasthenia in Otterhounds. Am J Vet Res (in press)
Boudreaux MK, Dodds WJ, Slauson DO, Catalfamo JL: Impaired cAMP metabolism associated with abnormal function of thrombopathic canine platelets. Biochem Biophys Res Commun 140:595-601, 1986[Medline]
Boudreaux MK, Kvam K, Dillon AR, Bourne C, Scott M, Schwartz KA, Toivio-Kinnucan M: Type I Glanzmann's thrombasthenia in a Great Pyrenees dog. Vet Pathol 33:503-511, 1996[Abstract]
Boudreaux MK, Lipscomb DL, Catalfamo JL: Novel mutations within calcium binding domains of canine platelet GPIIb cause Type I Glanzmann's thrombasthenia. Blood 94:(10) (Suppl 1, Part 2) 77b, 1999 [abstract]
Braunsteiner H, Pakesch F: Thrombocytoasthenia and thrombocytopathia: old names and new diseases. Blood 11:965-976, 1956[Abstract/Free Full Text]
Bray PF: Inherited diseases of platelet glycoproteins: considerations for rapid molecular characterization. Thromb Haemost 72:492-502, 1994[Medline]
Bray PF, Rosa J-P, Johnston GI, Shiu DT, Cook RG, Lau C, Kan YW, McEver RP, Shuman MA: Platelet glycoprotein IIb: chromosomal localization and tissue expression. J Clin Invest 80:1812-1817, 1987[Medline]
Bray PF, Shuman MA: Identification of an abnormal gene for the GPIIIa subunit of the platelet fibrinogen receptor resulting in Glanzmann's thrombasthenia. Blood 75:881-888, 1990[Abstract/Free Full Text]
Burk CD, Newman PJ, Lyman S, Gill J, Coller BS, Poncz M: A deletion in the gene for glycoprotein IIb associated with Glanzmann's thrombasthenia. J Clin Invest 87:270-276, 1991[Medline]
Byzova TV, Plow EF: The PlA2 allele and cardiovascular disease: the pro33 and con. J Clin Invest 105:697-698, 2000[Free Full Text]
Caen JP, Castaldi PA, Leclerc JC, Inceman S, Larrieu MJ, Probst M, Bernard J: Congenital bleeding disorders with long bleeding time and normal platelet count. I. Glanzmann's thrombasthenia. Am J Med 41:4-26, 1966[CrossRef]
Calvete JJ: Clues for understanding the structure and function of a prototypic human integrin: the platelet glycoprotein IIb/IIIa complex. Thromb Haemost 72:1-15, 1994[Medline]
Calvete JJ, Alvarez MV, Gonzalez-Rodriguez J: Quantitation and subcellular distribution of GPIIb and GPIIIa in human platelets and in the external platelet surface. Characterization of these glycoproteins isolated from the different subcellular fractions. In: Monoclonal antibodies and human blood platelets, ed. McGregor JL, p 179, INSERM Symposium No 27. Elsevier, Amsterdam 1986
Calvete JJ, Henschen A, Gonzalez-Rodriguez J: Assignment of disulfide bonds in human platelet GPIIIa. A disulfide pattern for the ß-subunits of the integrin family. Biochem J 274:63-71, 1991[Medline]
Calvete JJ, Mann K, Alvarez MV, Lopez MM, Gonzalez-Rodriquez J: Proteolytic dissection of the isolated platelet fibrinogen receptor, integrin GPIIb/IIIa. Localization of GPIIb and GPIIIa sequences putatively involved in the subunit interface and in intrasubunit and intrachain contacts. Biochem J 282:523-532, 1992[Medline]
Catalfamo JL, Raymond SL, White JG, Dodds WJ: Defective platelet-fibrinogen interaction in hereditary canine thrombopathia. Blood 67:1568-1577, 1986[Abstract/Free Full Text]
Charo IF, Nanizzi L, Phillips DR, Hsu MA, Scarborough RM: Inhibition of fibrinogen binding to GPIIb-IIIa by a GPIIIa peptide. J Biol Chem 266:1415-1421, 1991[Abstract/Free Full Text]
Chen F, Coller BS, French DL: Homozygous mutation of platelet glycoprotein IIIa (ß3) Cys374-Tyr in a Chinese patient with Glanzmann thrombasthenia. Blood 82:163a, 1993 [abstract]
Cieutat A-M, Rosa J-P, Letourneur F, Poncz M, Rifat S: A comparative analysis of cDNA-derived sequences for rat and mouse ß3 integrins (GPIIIa) with their human counterpart. Biochem Biophys Res Comm 193:771-778, 1993[CrossRef][Medline]
Clark EA, Shattil SJ, Brugge JS: Regulation of protein tyrosine kinases in platelets. Trends Biochem Sci 19:464-469, 1994[CrossRef][Medline]
Clark EA, Shattil SJ, Ginsberg MH, Bolen J, Brugge JS: Regulation of the protein tyrosine kinase, pp72Syk, by platelet agonists and the integrin, IIbß3. J Biol Chem 46:28859-28864, 1994
Cohen I, Burk DL, White JG: The effect of peptides and monoclonal antibodies that bind to platelet glycoprotein IIb–IIIa complex on the development of clot tension. Blood 73:1880-1887, 1989[Abstract/Free Full Text]
Coller B, Cheresh DA, Asch E, Seligsohn U: Platelet vitronectin receptor expression differentiates Iraqi-Jewish from Arab patients with Glanzmann's thrombasthenia in Israel. Blood 77:75-83, 1991[Abstract/Free Full Text]
Coller BS: Platelet GPIIb/IIIa antagonists: the first anti-integrin receptor therapeutics. J Clin Invest 100(11) (Suppl) S57-S60, 1997[Medline]
Coller BS, Seligsohn U, Little PA: Type I Glanzmann thrombasthenia patients from the Iraqi-Jewish and Arab populations in Israel can be differentiated by platelet glycoprotein IIIa immunoblot analysis. Blood 69:1696-1703, 1987[Abstract/Free Full Text]
Dodds WJ: Familial canine thrombocytopathy. Thromb Diath Haemorrh Suppl 26:241-248, 1967[Medline]
D'Souza SE, Ginsberg MH, Burke TA, Lam SCT, Plow EF: Localization of an Arg-Gly-Asp recognition site within an integrin adhesion receptor. Science 242:91-93, 1988[Abstract/Free Full Text]
D'Souza SE, Ginsberg MH, Burke TA, Plow EF: The ligand binding site of the platelet integrin receptor GPIIb–IIIa is proximal to the second calcium binding domain of its subunit. J Biol Chem 265:3440-3446, 1990[Abstract/Free Full Text]
D'Souza SE, Ginsberg MH, Lam SC-T, Plow E: Chemical cross-linking of arginyl-glycyl-aspartic acid peptides on adhesion receptors on platelets. J Biol Chem 263:3943-3951, 1988[Abstract/Free Full Text]
D'Souza SE, Ginsberg MH, Matsueda GR, Plow EF: A discrete sequence in a platelet integrin is involved in ligand recognition. Nature 350:66-68, 1991[CrossRef][Medline]
D'Souza SE, Haas TA, Piotrowicz RS, Byers-Ward V, McGrath DE, Soule HR, Cierniewski C, Plow EF, Smith JW: Ligand and cation binding are dual functions of a discrete segment of the integrin ß3 subunit: cation displacement is involved in ligand binding. Cell 79:659-667, 1994[CrossRef][Medline]
Duperray A, Troesch A, Berthier R, Chagnon E, Frachet P, Uzan G, Marguerie G: Biosynthesis and assembly of platelet GPIIb–IIIa in human megakaryocytes: evidence that assembly between pro-GPIIb and GPIIIa is a prerequisite for expression of the complex on the cell surface. Blood 74:1603-1611, 1989[Abstract/Free Full Text]
Fitzgerald LA, Steiner B, Rall SC, Jr Lo S-S, Phillips DR: Protein sequence of endothelial glycoprotein IIIa derived from a cDNA clone. Identity with platelet glycoprotein IIIa and similarity to "integrin.". J Biol Chem 262:3936-3939, 1987[Abstract/Free Full Text]
Fonio A, Schwendener J: Die thrombocyten des menschlichen blutes. Bern 1942
Fox JB: The platelet cytoskeleton. Thromb Haemost 70:884-893, 1993[Medline]
Frachet P, Duperray A, Delachanal E, Marguerie G: Role of the transmembrane and cytoplasmic domains in the assembly and surface exposure of the platelet integrin GPIIb-IIIa. Biochemistry 31:2408-2415, 1992[Medline]
French DL: The molecular genetics of Glanzmann's thrombasthenia. Platelets 9:5-20, 1998[CrossRef]
French DL, Coller BS: Hematologically important mutations: Glanzmann thrombasthenia. Blood Cells Mol Dis 23:(3) 39-51, 1997[CrossRef][Medline]
French DL, Seligsohn U: Platelet glycoprotein IIb/IIIa receptors and Glanzmann's thrombasthenia. Arterioscler Thromb Vasc Biol 20:607-610, 2000[Free Full Text]
Gawaz MP, Loftus JC, Bajt ML, Frojmovic MM, Plow EF, Ginsberg MH: Ligand bridging mediates integrin IIbß3 (platelet GPIIb–IIIa) dependent homotypic and heterotypic cell–cell interactions. J Clin Invest 88:1128-1134, 1991[Medline]
George JN, Caen JP, Nurden AT: Glanzmann's thrombasthenia: the spectrum of clinical disease. Blood 75:1383-1395, 1990[Free Full Text]
George JN, Nurden AT: Inherited disorders of the platelet membrane: Glanzmann's thrombasthenia and Bernard–Soulier syndrome. In: Hemostasis and Thrombosis, ed. Colman RW, Hirsh J, Marder VJ, and Salzman EW, 2nd ed., p 726, JB Lippincott, Philadelphia, PA 1987
George JN, Nurden AT, Phillips DR: Molecular defects in interactions of platelets with the vessel wall. New Engl J Med 311:1084-1098, 1984[Abstract]
Ginsberg MH, Forsyth J, Lightsey A, Chediak J, Plow EF: Reduced surface expression and binding of fibronectin by thrombin-stimulated thrombasthenic platelets. J Clin Invest 71:619-624, 1983[Medline]
Ginsberg MH, Du X, Plow EF: Inside-out integrin signaling. Curr Opin Cell Biol 4:766-771, 1992[CrossRef][Medline]
Ginsberg MH, Lightsey A, Kunicki TJ, Kaufmann A, Marguerie G, Plow EF: Divalent cation regulation of the surface orientation of platelet membrane glycoprotein IIb: correlation with fibrinogen binding function and definition of a novel variant of Glanzmann's thrombasthenia. J Clin Invest 78:1103-1111, 1986[Medline]
Ginsberg MH, Xiaoping D, O'Toole TE, Loftus JC, Plow EF: Platelet integrins. Thromb Haemost 70:87-93, 1993[Medline]
Glanzmann E: Hereditare hamorrhagische thrombasthenie: Ein beitrag zur pathologie der blut plattchen. J Kinderkr 88:113-141, 1918
Grimaldi CM, Chen F, Scudder LE, Coller BS, French DL: A Cys374Tyr homozygous mutation of platelet glycoprotein IIIa (ß3) in a Chinese patient with Glanzmann's thrombasthenia. Blood 88:1666-1675, 1996[Abstract/Free Full Text]
Gu J-M, Xu W-F, Wang X-D, Wu Q-Y, Chi C-W, Ruan C-G: Identification of a nonsense mutation at amino acid 584-arginine of platelet glycoprotein IIb in patients with type I Glanzmann thrombasthenia. Br J Haematol 83:442-449, 1993[Medline]
Guilino D, Boudignon C, Zhang Y, Concord E, Rabiet M-J, Marguerie G: Ca2+-binding properties of the platelet glycoprotein IIb ligand-interacting domain. J Biol Chem 267:1001-1007, 1992[Abstract/Free Full Text]
Haas TA, Plow EF: The cytoplasmic domain of IIbß3: a ternary complex of the integrin and ß subunits and a divalent cation. J Biol Chem 271:6017-6026, 1996[Abstract/Free Full Text]
Haimovich B, Lipfert L, Brugge JS, Shattil SJ: Tyrosine phosphorylation and cytoskeletal reorganization in platelets are triggered by interaction of integrin receptors with their immobilized ligands. J Biol Chem 268:15868-15877, 1993[Abstract/Free Full Text]
Handagama P, Scarborough RM, Shuman MA, Bainton DF: Endocytosis of fibrinogen into megakaryocyte and platelet -granules is mediated by IIbß3 (glycoprotein IIb–IIIa). Blood 82:135-138, 1993[Abstract/Free Full Text]
Hardisty RM, Dormandy KM, Hutton RA: Thrombasthenia: studies on three cases. Br J Haematol 10:371-387, 1964[Medline]
Heidenreich R, Eisman R, Surrey S, Delgrosso K, Bennett JS, Schwartz E, Poncz M: Organization of the gene for platelet glycoprotein IIb. Biochem 29:1232-1244, 1990[CrossRef][Medline]
Huang M-M, Lipfert L, Cunningham M, Brugge JS, Ginsberg MH, Shattil SJ: Adhesive ligand binding to integrin IIbß3 stimulates tyrosine phosphorylation of novel protein substrates before phosphorylation of pp125FAK. J Cell Biol 122:437-483, 1993
Hynes RO: Integrins: versatility, modulation, and signalling in cell adhesion. Cell 69:11-25, 1992[CrossRef][Medline]
Isenberg WM, McEver RP, Phillips DR, Shuman MA, Bainton DF: The platelet fibrinogen receptor: an immunogold-surface replica study of agonist-induced ligand binding and receptor clustering. J Cell Biol 104:1655-1663, 1987[Abstract]
Jackson DE, White MM, Jennings LK, Newman PJ: A Ser162Leu mutation within glycoprotein (GP) IIIa (integrin ß3) results in an unstable alpha IIb beta 3 complex that retains partial function in a novel form of type II Glanzmann thrombasthenia. Thromb Haemost 80:42-48, 1998[Medline]
Jennings LK, Phillips DR: Purification of glycoproteins IIb and IIIa from human platelet plasma membranes and characterization of a calcium-dependent glycoprotein IIb–IIIa complex. J Biol Chem 257:10458-10466, 1982[Abstract/Free Full Text]
Johnstone IB, Lotz F: An inherited platelet function defect in basset hounds. Can Vet J 20:211-215, 1979[Medline]
Kapeller R, Cantley LC: Phosphatidylinositol 3-kinase. BioEssays 16:565-576, 1994[CrossRef][Medline]
Khanduri U, Pulimood R, Sudarsanam A, Carman RH, Jadhav M, Pereira S: Glanzmann's thrombasthenia: a review and report of 42 cases from South India. Thromb Haemost 46:717-721, 1981[Medline]
Kieffer N, Phillips DR: Platelet membrane glycoproteins. Functions in cellular interactions. Ann Rev Cell Biol 6:329-357, 1990[CrossRef]
Kolodziej MA, Vilaire G, Gonder D, Poncz M, Bennett JS: Study of the endoproteolytic cleavage of platelet glycoprotein IIb using oligonucleotide-mediated mutagenesis. J Biol Chem 266:23499-23504, 1991[Abstract/Free Full Text]
Kolodziej MA, Vilaire G, Rifat S, Poncz M, Bennett JS: Effect of deletion of glycoprotein IIb exon 28 on the expression of the platelet glycoprotein IIb/IIIa complex. Blood 78:2344-2353, 1991[Abstract/Free Full Text]
Kouns WC, Steiner B, Kunicki TJ, Moog S, Jutzi J, Jennings LK, Cazenave JP, Lanza F: Activation of the fibrinogen binding site on platelets isolated from a patient with the Strasbourg I variant of Glanzmann's thrombasthenia. Blood 84:1108-1115, 1994[Abstract/Free Full Text]
Kovacsovics TJ, Bachelot C, Toker A, Vlahos C, Duckworth B, Cantley LC, Hartwig JH: Phosphoinositide 3-kinase inhibition spares actin assembly in activating platelets, but reverses platelet aggregation. J Biol Chem 270:11358-11366, 1995[Abstract/Free Full Text]
Lanza F, Kieffer N, Phillips DR, Fitzgerald LA: Characterization of the human platelet glycoprotein IIIa gene. J Biol Chem 265:18098-18103, 1990[Abstract/Free Full Text]
Lanza F, Stierle A, Fournier D, Morales M, Andre G, Nurden AT, Cazenave JP: A new variant of Glanzmann's thrombasthenia (Strasbourg I). Platelets with functionally defective glycoprotein IIb–IIIa complexes and a glycoprotein IIIa 214Arg-214Trp mutation. J Clin Invest 89:1995-2004, 1992[Medline]
Leong L, Hughes PE, Schwartz MA, Ginsberg MH, Shattil SJ: Integrin signaling: roles for the cytoplasmic tails of alpha IIb beta 3 in the tyrosine phosphorylation of pp125 FAK. J Cell Sci 108:3817-3825, 1995[Abstract]
Lipfert L, Haimovich B, Schaller MD, Cobb BS, Parsons JT, Brugge JS: Integrin-dependent phosphorylation and activation of the protein tyrosine kinase pp125FAK in platelets. J Cell Biol 119:905-912, 1992[Abstract]
Lipscomb DL, Bourne C, Boudreaux MK: DNA sequence of the canine platelet ß3 gene from cDNA: comparison of canine and mouse ß3 to segments that encode alloantigenic sites and functional domains of ß3 in human beings. J Lab Clin Med 134:313-321, 1999[CrossRef][Medline]
Lipscomb DL, Bourne C, Boudreaux MK: Two genetic defects in IIb are associated with Type I GT in a Great Pyrenees dog: a 14-base insertion in exon 13 and a splicing defect of intron 13. Vet Pathol 37:581-588, 2000[Abstract/Free Full Text]
Lipscomb DL, Bourne C, Boudreaux MK: Nucleotide sequence of the canine IIb gene from platelet-derived cDNA: comparison to segments that encode functional domains and alloantigenic sites in human beings. Am J Vet Res (in press)
Loftus JC, O'Toole TE, Plow EF, Glass A, Frelinger AL, III Ginsberg MH: A ß3 integrin mutation abolishes ligand binding and alters divalent cation-dependent conformation. Science 249:915-918, 1990[Abstract/Free Full Text]
Loftus JC, Plow EF, Frelinger AL, III D'Souza SE, Dixon D, Lacy J, Sorge J, Ginsberg MH: Molecular cloning and chemical synthesis of a region of platelet GPIIb involved in adhesive function. Proc Natl Acad Sci USA 840:7114-7118, 1987
McHugh KP, Hodivala-Dilke K, Zheng M-H, Namba N, Lam J, Novack D, Feng X, Ross FP, Hynes RO, Teitelbaum SL: Mice lacking beta3 integrins are osteosclerotic because of dysfunctional osteoclasts. J Clin Invest 105:433-440, 2000[Abstract/Free Full Text]
Morel-Kopp M-C, Kaplan C, Proulle V, Jallu V, Melchior C, Peyruchaud O, Aurousseau MH, Caffer N: A three amino acid deletion in glycoprotein IIIa is responsible for type I Glanzmann's thrombasthenia: importance of residues Ile325Pro326Gly327 for ß3 integrin subunit association. Blood 90:669-677, 1997[Abstract/Free Full Text]
Naegeli D: Blut krankheiten and blut diagnostik, vol I. Springer-Verlag, Berlin 1931
Nemoto Y, Namba T, Teru-uchi T, Ushikubi F, Morii N, Narumiya S: A rho gene product in human blood platelets. I. Identification of the platelet substrate for botulinum C3 ADP-ribosyltransferase as RhoA protein. J Biol Chem 267:20916-20920, 1992[Abstract/Free Full Text]
Newman PJ, Seligsohn U, Lyman S, Coller BS: The molecular genetic basis of Glanzmann thrombasthenia in the Iraqi-Jewish and Arab populations in Israel. Proc Natl Acad Sci USA 88:3160-3164, 1991[Abstract/Free Full Text]
Niiya K, Hodson E, Bader R, Byers-Ward V, Koziol JA, Plow EF, Ruggeri ZM: Increased surface expression of the membrane glycoprotein IIb/IIIa complex induced by platelet activation. Relationship to the binding of fibrinogen and platelet aggregation. Blood 70:475-483, 1987[Abstract/Free Full Text]
Nurden AT: Polymorphisms of human platelet membrane glycoproteins: structure and clinical significance. Thromb Haemost 74:345-351, 1995[Medline]
Nurden AT, Caen JP: An abnormal platelet glycoprotein pattern in three cases of Glanzmann's thrombasthenia. Br J Haematol 28:253-260, 1974[Medline]
Nurden AT, Rosa J-P, Fournier D, Legrand C, Didry D, Parquet A, Pidard D: A variant of Glanzmann's thrombasthenia with abnormal glycoprotein IIb–IIIa complexes in the platelet membrane. J Clin Invest 79:962-969, 1987[Medline]
O'Toole TE, Loftus JC, Plow EF, Glass AA, Harper JR, Ginsberg MH: Efficient surface expression of platelet GPIIb–IIIa requires both subunits. Blood 74:14-18, 1989[Abstract/Free Full Text]
Peretz H, Rosenberg N, Usher S, Graff E, Newman PJ, Coller BS, Seligsohn U: Glanzmann's thrombasthenia associated with deletion-insertion and alternative splicing in the glycoprotein IIb gene. Blood 85:414-420, 1995[Abstract/Free Full Text]
Peyruchaud O, Nurden AT, Milet S, Macchi L, Pannochia A, Bray PF, Kieffer N, Bourre F: R to Q amino acid substitution in the GFFKR sequence of the cytoplasmic domain of the integrin alpha IIb subunit in a patient with a Glanzmann's thrombasthenia-like syndrome. Blood 92:4178-4187, 1998[Abstract/Free Full Text]
Phillips DR, Agin PP: Platelet membrane defects in Glanzmann's thrombasthenia: evidence for decreased amounts of two major glycoproteins. J Clin Invest 60:535-545, 1977[Medline]
Phillips DR, Charo IF, Parise LV, Fitzgerald LA: The platelet membrane glycoprotein IIb–IIIa complex. Blood 71:831-843, 1988[Free Full Text]
Phillips DR, Jenkins CSP, Luscher DF, Larrieu MJ: Molecular differences of exposed surface proteins on thrombasthenic platelet plasma membranes. Nature 257:599-600, 1975[Medline]
Plow EF, Byzova T: The biology of glycoprotein IIb–IIIa. Coron Artery Dis 10:547-551, 1999[Medline]
Plow EF, Ginsberg MH: Cellular adhesion: GPIIb–IIIa as a prototypic adhesion receptor. Prog Thromb Haemost 9:117-156, 1989
Poncz M, Eisman R, Heidenreich R, Silver SM, Vilaire G, Surrey S, Schwartz E, Bennett JS: Structure of the platelet membrane glycoprotein IIb. Homology to the alpha subunits of the vitronectin and fibronectin membrane receptors. J Biol Chem 262:8476-8482, 1987[Abstract/Free Full Text]
Poncz M, Rifat S, Coller BS, Newman PJ, Shattil SJ, Parrella T, Fortina P, Bennett JS: Glanzmann thrombasthenia secondary to a Gly273Asp mutation adjacent to the first calcium-binding domain of platelet glycoprotein IIb. J Clin Invest 93:172-179, 1994[Medline]
Rahman S, Lu X, Kakkar VV, Authi KS: The integrin IIbß3 contains distinct and interacting binding sites for snake-venom RGD (Arg-Gly-Asp) proteins. Biochem J 312:223-232, 1995[Medline]
Raymond SL, Dodds WJ: Platelet membrane glycoproteins in normal dogs and dogs with hemostatic defects. J Lab Clin Med 93:607-613, 1979[Medline]
Ribeiro JMC: Blood-feeding arthropods: live syringes or invertebrate pharmacologists? Infect Agents Dis 4:143-152, 1995[Medline]
Rosa J-P, Bray PF, Gayet O, Johnston GI, Cook RG, Jackson KW, Shuman MA, McEver RP: Cloning of glycoprotein IIIa cDNA from human erythroleukemia cells and localization of the gene to chromosome 17. Blood 72:593-600, 1988[Abstract/Free Full Text]
Rosa J-P, McEver RP: Processing and assembly of the integrin, glycoprotein IIb–IIIa, in HEL cells. J Biol Chem 264:12596-12603, 1989[Abstract/Free Full Text]
Ruan J, Peyruchaud O, Alberio L, Valles G, Clemetson K, Bourre F, Nurden AT: Double heterozygosity of the GPIIb gene in a Swiss patient with Glanzmann's thrombasthenia. Br J Haematol 102:918-925, 1998[CrossRef][Medline]
Ruggeri ZM, Bader R, DeMarco L: Glanzmann thrombasthenia: deficient binding of von Willebrand factor to thrombin-stimulated platelets. Proc Natl Acad Sci USA 79:6038-6041, 1982[Abstract/Free Full Text]
Schlegel N, Gayet O, Morel-Kopp M-C, Wyler B, Hurtlaud-Roux M-F, Kaplan C, McGregor J: The molecular genetic basis of Glanzmann's thrombasthenia in a Gypsy population in France: identification of a new mutation in the IIb gene. Blood 86:977-982, 1995[Abstract/Free Full Text]
Schror K: Antiplatelet drugs. A comparative review. Drugs 50:(1) 7-28, 1995[Medline]
Seligsohn U, Rososhansky S: A Glanzmann's thrombasthenia cluster among Iraqi Jews in Israel. Thromb Haemost 52:230-231, 1984[Medline]
Shattil SJ: Regulation of platelet anchorage and signaling by integrin IIbß3. Thromb Haemost 70:224-228, 1993[Medline]
Shattil SJ: Function and regulation of the ß3 integrins in hemostasis and vascular biology. Thromb Haemost 74:149-155, 1995[Medline]
Shattil SJ, Ginsberg MH, Brugge JS: Adhesive signaling in platelets. Curr Opin Cell Biol 6:695-704, 1994[CrossRef][Medline]
Shattil SJ, Hoxie JA, Cunningham M, Brass LF: Changes in the platelet membrane glycoprotein IIb–IIIa complex during platelet activation. J Biol Chem 260:11107-11114, 1985[Abstract/Free Full Text]
Sims PJ, Ginsberg MH, Plow EF, Shattil SJ: Effect of platelet activation on the conformation of the plasma membrane glycoprotein IIb–IIIa complex. J Biol Chem 266:7345-7352, 1991[Abstract/Free Full Text]
Sosnoski DM, Emanuel BS, Hawkins AL, van Tuilen P, Ledbetter DH, Nussbaum RL, Kaos F-T, Schwartz E, Phillips DR, Bennett JS, Fitzgerald LA, Poncz M: Chromosomal localization of the genes for the vitronectin and the fibronectin receptors subunits and for platelet glycoproteins IIb and IIIa. J Clin Invest 81:1993-1998, 1988[Medline]
Thornton MA, Poncz M: Characterization of the murine platelet aIIb gene and encoded cDNA. Blood 94:3947-3951, 1999[Abstract/Free Full Text]
Tomiyama Y, Kshiwagi H, Kosugi S, Shiraga M, Kanayama Y, Kurata Y, Matsusawa Y: Abnormal processing of the glycoprotein IIb transcript due to a nonsense mutation in exon 17 associated with Glanzmann's thrombasthenia. Thromb Haemost 73:756-762, 1995[Medline]
Tozer EC, Liddington RC, Sutcliffe MJ, Smeeton AH, Loftus JC: Ligand binding to integrin IIbß3 is dependent on a MIDAS-like domain in the ß3 subunit. J Biol Chem 271:21978-21984, 1996[Abstract/Free Full Text]
Tronik-Le Roux D, Roullot V, Poujol C, Kortulewski T, Nurden P, Marguerie G: Thrombasthenic mice generated by replacement of the integrin IIb gene: demonstration that transcriptional activation of this megakaryocytic locus precedes lineage commitment. Blood 96:1399-1408, 2000[Abstract/Free Full Text]
Wagner CL, Mascelli MA, Neblock DS, Weisman HF, Coller BS, Jordan RE: Analysis of GPIIb/IIIa receptor number by quantification of 7E3 binding to human platelets. Blood 88:907-914, 1996[Abstract/Free Full Text]
Walter DH, Schachinger V, Elsner M, Dimmeler S, Zeiher A: Platelet glycoprotein IIIa polymorphisms and risk of coronary stent thrombosis. Lancet 350:1217-1219, 1997[CrossRef][Medline]
Weisel JW, Nagaswami C, Vilaire G, Bennett JS: Examination of the platelet membrane glycoprotein IIb–IIIa complex and its interaction with fibrinogen and other ligands by electron microscopy. J Biol Chem 267:16637-16643, 1992[Abstract/Free Full Text]
Weiss EJ, Bray PF, Tayback MT, Schulman SP, Kickler TS, Beckler LC: A polymorphism of a platelet glycoprotein receptor as an inherited risk factor for coronary thrombosis. N Engl J Med 334:1090-1094, 1996[Abstract/Free Full Text]
Wencel-Drake JD, Plow EF, Kunicki TJ, Woods VL, Keller DM, Ginsberg MH: Localization of internal pools of membrane glycoprotein involved in platelet adhesive responses. Am J Pathol 124:324-334, 1986[Abstract]
Wilcox DA, Paddock CM, Lyman S, Gill JC, Newman PJ: Glanzmann thrombasthenia resulting from a single amino acid substitution between the second and third calcium-binding domains of GPIIb: role of the GPIIb amino terminus in integrin subunit association. J Clin Invest 95:1553-1560, 1995[Medline]
Wilcox DA, Wautier JL, Pidard D, Newman PJ: A single amino acid substitution flanking the fourth calcium binding domain of IIb prevents maturation of the IIbß3 integrin complex. J Biol Chem 269:4450-4457, 1994[Abstract/Free Full Text]
Wilhide CC, Jin Y, Guo Q, Li L, Li S-X, Rubin E, Bray PF: The human integrin ß3 gene is 63 kb and contains a 5'-UTR sequence regulating expression. Blood 90:3951-3961, 1997[Abstract/Free Full Text]
Woods VL, Jr Wolff LE, Keller DM: Resting platelets contain a substantial centrally located pool of glycoprotein IIb–IIIa complex which may be accessible to some but not other extracellular proteins. J Biol Chem 261:15242-15251, 1986[Abstract/Free Full Text]
Ylanne J, Huuskonen J, O'Toole TE, Ginsberg MH, Virtanen I, Gahmberg CG: Mutation of the cytoplasmic domain of the integrin ß3 subunit. J Biol Chem 270:9550-9557, 1995[Abstract/Free Full Text]
Zhang J, Fry MJ, Waterfield MD, Jaken S, Liao L, Fox JEB, Rittenhouse SE: Activated phosphoinositide 3-kinase associates with membrane skeleton in thrombin-exposed platelets. J Biol Chem 267:4686-4692, 1992[Abstract/Free Full Text]
Zimrin AB, Gidwitz S, Lord S, Schwartz E, Bennett JS, White GC, II Poncz M: The genomic organization of platelet glycoprotein IIIa. J Biol Chem 265:8590-8595, 1990[Abstract/Free Full Text]
Zucker MB, Pert JH, Hilgartner MW: Platelet function in a patient with thrombasthenia. Blood 28:524-534, 1966[Abstract/Free Full Text]
Request reprints from Dr. Mary K. Boudreaux, 166 Green Hall, College of Veterinary Medicine, Auburn University, Auburn, AL 36849-5519 (USA). Email: boudrmk@vetmed.auburn.edu.
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