title: Alterations of the platelet proteome in type I Glanzmann thrombasthenia caused by different homozygous delG frameshift mutations in ITGA2B.
abstract: Glanzmann thrombasthenia (GT) is one of the best characterised inherited platelet function disorders but global platelet proteome has not been determined in these patients. We investigated the proteome and function of platelets from two patients with type I GT, caused by different homozygous ITGA2b mutations, from family members and unrelated controls. The global proteome of highly purified washed platelets was quantified by liquid chromatography-mass spectrometry (LC-MS) and targeted MS-methods. Platelet function was analysed by flow cytometry, light transmission aggregometry and flow-based assays. Platelets from GT patients showed less than 5 % relative levels of the integrin subunit αIIband 5-9 % fibrinogen compared to controls. These patients demonstrated loss of αIIbβ3-dependent platelet function, but normal platelet granule secretion induced by physiological agonists. Platelets from heterozygous family members of a patient expressed 50-60 % of control αIIblevels which were sufficient for normal αIIbβ3-dependent platelet function. Studying type I GT as model disease we established quantitative LC-MS to detect and clearly distinguish normal platelets, platelets from GT heterozygotes and platelets from GT patients. Diminished levels of factor XIIIB chain, plasminogen and carboxypeptidase 2B were identified in thrombasthenic platelets. Additionally, GT platelets showed up to 2.5-fold increased levels of FcγRIIA and laminin-α4 chain. Elevated levels of platelet FcγRIIA was associated with increased CD63-surface expression after FcγRIIA-crosslinking in one GT-patient which might present a compensatory mechanism of platelet activation in GT. We demonstrate that quantitative LC-MS based proteomics is suitable to validate known but also to identify previously unknown protein level changes of dysfunctional platelets.
authors.forename: Stefan
authors.initials: S
authors.lastname: Loroch
authors.forename: Katharina
authors.initials: K
authors.lastname: Trabold
authors.forename: Stepan
authors.initials: S
authors.lastname: Gambaryan
authors.forename: Cora
authors.initials: C
authors.lastname: Reiß
authors.forename: Kathrin
authors.initials: K
authors.lastname: Schwierczek
authors.forename: Ingrid
authors.initials: I
authors.lastname: Fleming
authors.forename: Albert
authors.initials: A
authors.lastname: Sickmann
authors.forename: Wolfgang
authors.initials: W
authors.lastname: Behnisch
authors.forename: Barbara
authors.initials: B
authors.lastname: Zieger
authors.forename: René P
authors.initials: RP
authors.lastname: Zahedi
authors.forename: Ulrich
authors.initials: U
authors.lastname: Walter
authors.affiliation: Kerstin Jurk, Center for Thrombosis and Hemostasis (CTH), University Medical Center Mainz, Langenbeckstr. 1, 55131 Mainz, Germany, Tel.: +49 6131 178278, Fax: +49 6131 176238, E-mail: kerstin.jurk@unimedizin-mainz.de.
authors.forename: Kerstin
authors.initials: K
authors.lastname: Jurk
mesh_terms: D000328:Adult; D001792:Blood Platelets / Q000378:metabolism*; D001798:Blood Proteins / Q000378:metabolism*; D002648:Child; D002851:Chromatography, High Pressure Liquid; D004252:DNA Mutational Analysis; D005260:Female; D016368:Frameshift Mutation; D020022:Genetic Predisposition to Disease; D006720:Homozygote; D006801:Humans; D039421:Integrin alpha2 / Q000235:genetics*; D008297:Male; D013058:Mass Spectrometry; D010375:Pedigree; D010641:Phenotype; D010979:Platelet Function Tests; D011237:Predictive Value of Tests; D020543:Proteome; D040901:Proteomics / Q000379:methods*; D013915:Thrombasthenia / Q000097:blood / Q000175:diagnosis / Q000235:genetics*
chemical_list: D001798:Blood Proteins; C056564:ITGA2B protein, human; D039421:Integrin alpha2; D020543:Proteome
keywords: Glanzmann thrombasthenia; haemorrhage; platelets; proteomics; αIIbβ3 integrin