The first comprehensive and quantitative analysis of human platelet protein composition allows the comparative analysis of structural and functional pathways

Abstract

Antiplatelet treatment is of fundamental importance in combatting functions/dysfunction of platelets in the pathogenesis of cardiovascular and inflammatory diseases. Dysfunction of anucleate platelets is likely to be completely attributable to alterations in posttranslational modifications and protein expression. We therefore examined the proteome of platelets highly purified from fresh blood donations, using elaborate protocols to ensure negligible contamination by leukocytes, erythrocytes, and plasma. Using quantitative mass spectrometry, we created the first comprehensive and quantitative human platelet proteome, comprising almost 4000 unique proteins, estimated copy numbers for similar to 3700 of those, and assessed intersubject (4 donors) as well as intrasubject (3 different blood samples from 1 donor) variations of the proteome. For the first time, our data allow for a systematic and weighted appraisal of protein networks and pathways in human platelets, and indicate the feasibility of differential and comprehensive proteome analyses from small blood donations. Because 85% of the platelet proteome shows no variation between healthy donors, this study represents the starting point for disease-oriented platelet proteomics. In the near future, comprehensive and quantitative comparisons between normal and well-defined dysfunctional platelets, or between platelets obtained from donors at various stages of chronic cardiovascular and inflammatory diseases will be feasible

Tetraspanin Tspan9 regulates platelet collagen receptor GPVI lateral diffusion and activation

“…Tspan9 has relatively strong sequence identity with Tspan4 (55%) and CD53 (43%), for which knockout mice phenotypes have yet to be reported. CD53 is restricted to leukocytes [55] and is absent from platelets [56, 57], so its expression does not appear to overlap with Tspan9. Tspan4 appears to be more widely expressed [58] but not by platelets [56, 57].…”

“…CD53 is restricted to leukocytes [55] and is absent from platelets [56, 57], so its expression does not appear to overlap with Tspan9. Tspan4 appears to be more widely expressed [58] but not by platelets [56, 57]. These expression profiles could explain how a platelet phenotype has been identified in the Tspan9-deficient mice.…”

Conventional protein kinase C isoforms differentially regulate ADP- and thrombin-evoked Ca2+ signalling in human platelets

“…In cardiac muscle and several other cell types, Na + /K + -ATPase activity is modulated by association with members of the FXYD family of proteins [55]. However, no members of the FXYD family have been detected in the platelet proteome [56]. Another possibility is that there is a change in surface expression of the Na + /K + -ATPase in thrombin-stimulated platelets.…”

Extracellular chloride is required for efficient platelet aggregation

“…Early patch clamp recordings demonstrated functional expression of Ca 2+ -activated Cl − channels in platelets [7, 8] and a megakaryocyte-like DAMI cell line [9]. Proteomic [10] and transcriptomic [11] analyses have since identified numerous anion channels that may be expressed by platelets. Of these, functional expressions of CLIC1 (Intracellular Cl − channel-1) [12], TMEM16F [13], and pannexin-1 [14] have been confirmed.…”