1,721,018 research outputs found
N-Terminal combined fractional diagonal chromatographic (COFRADIC) analysis of the human platelet proteome
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Platelets and their role in thrombotic and cardiovascular disease: the impact of proteomic analysis
No full textThis chapter provides an overview of how proteomics research impacts on our understanding of platelets. In addition to their role in hemostasis, inappropriate platelet activation is strongly related to the leading cause of death in Western societies: thrombotic cardiovascular disease. The known processes of platelet activation and the signaling mechanisms that regulate these are detailed here, but this knowledge is incomplete. Mass-spectrometry-based proteomics has already contributed to a growth in the understanding of platelets and presents itself as a tool that can unravel the details of the control of platelet function in health and disease through continuing refinements in technology and experimental design toward the development of diagnostic tools and antithrombotic drugs. © 2011 John Wiley and Sons, Inc
Isolation and characterization of cotiaractivase, a novel low molecular weight prothrombin activator from the venom of Bothrops cotiara.
No full textIn this study, we isolated a novel prothrombin activator from the venom of Bothrops cotiara, a Brazilian lance-headed pit viper (Cotiara, Jararaca preta, Biocotiara), which we have designated "cotiaractivase" (prefix: cotiar- from B. cotiara; suffix: -activase, from prothrombin activating activity). Cotiaractivase was purified using a phenyl-Superose hydrophobic interaction column followed by a Mono-Q anion exchange column. It is a single-chain polypeptide with a molecular weight of 22,931 Da as measured by mass spectroscopy. Cotiaractivase generated active alpha-thrombin from purified human prothrombin in a Ca2+-dependent manner as assessed by S2238 chromogenic substrate assay and SDS-PAGE. Cotiaractivase cleaved prothrombin at positions Arg271-Thr272 and Arg320-Ile321, which are also cleaved by factor Xa. However, the rate of thrombin generation by cotiaractivase was approximately 60-fold less than factor Xa alone and 17 x 10(6)-fold less than the prothrombinase complex. The enzymatic activity of cotiaractivase was inhibited by the chelating agent EDTA, whereas the serine protease inhibitor PMSF had no effect on its activity, suggesting that it is a metalloproteinase. Interestingly, S2238 inhibited cotiaractivase activity non-competitively, suggesting that this toxin contains an exosite that allows it to bind prothrombin independently of its active site. Tandem mass spectrometry and N-terminal sequencing of purified cotiaractivase identified peptides that were identical to regions of the cysteine-rich and disintegrin-like domains of known snake venom metalloproteinases. Cotiaractivase is a unique low molecular weight snake venom prothrombin activator that likely belongs to the metalloproteinase family of proteins
Platelet proteomics: state of the art and future perspective.
No full textPlatelets pose unique challenges to cell biologists due to their lack of nucleus and low levels of messenger RNA. Platelets cannot be cultured in great abundance or manipulated using common recombinant DNA technologies. As a result, platelet research has lagged behind that of nucleated cells. The advent of mass spectrometry and its application to protein biochemistry brought with it great hopes for the platelet community that are now being realized. This technology is ideally suited for identifying low-abundance proteins, protein-protein interactions, and post-translational modifications in complex protein mixtures. Over the past 10 years, proteomics has delivered in many ways, providing platelet biologists with a comprehensive list of proteins expressed in platelets, information on post-translational modifications, protein interactions and sub-cellular localization. Several novel and important platelet membrane proteins, including CLEC-2, CD148, G6b-B, G6f, and Hsp47, have been identified using proteomics-based approaches. New, more sensitive instrumentation and novel approaches are making it increasingly possible to identify ever lower amounts of proteins. In this chapter we highlight some of the major achievements of platelet proteomics to date, discussing challenges and how they were overcome. We also discuss new frontiers and applications of proteomics to platelets and microparticles in health and disease, as we strive to better understand the molecular mechanisms underlying the platelet response to vascular injury
Signalling Pathways Regulating Platelet Biogenesis
No full textPlatelet biogenesis is a complex process controlled by a combination of cell-extrinsic and cell-intrinsic factors. Cell-extrinsic factors include cytokines and growth factors, chemokines, extracellular matrix proteins, cell-cell interactions and shear forces within the bone marrow milieu that act on megakaryocytes. Cell-intrinsic factors include receptors and associated signalling pathways, cytoskeletal structures, lipid and cation concentrations found within megakaryocytes. Collectively, these two sets of factors control the differentiation, proliferation and survival of megakaryocytes and produce platelets. Recent discoveries have greatly increased our understanding of the molecular mechanisms controlling platelet biogenesis; however, major gaps remain in our knowledge regarding signalling events regulating the transition from megakaryopoiesis to thrombopoiesis, the triggering of proplatelet formation and platelet release and the inhibition of activation signals within megakaryocytes during the course of platelet biogenesis. A major step will be to map all of the signalling networks within megakaryocytes and elucidate their interconnectedness. In this chapter, we describe some of the major signalling pathways that regulate platelet biogenesis, novel modes of regulation and inhibitory mechanisms that prevent uncontrolled megakaryocyte and platelet activation. We also highlight key questions that remain to be addressed and propose potential mechanisms. It is only through a comprehensive understanding of how platelet biogenesis is regulated that we will be able to identify key signalling nodes that can be targeted to modulate platelet homeostasis in health and disease
Proplatelets slip slidin' away
No full textIn this issue of Blood, Bender et al provide compelling evidence that the motor protein cytoplasmic dynein provides the necessary force for microtubule sliding and proplatelet elongation from megakaryocytes.</p
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
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