Hematology Commons^™

The Function Of Ask1 In Sepsis And Stress-Induced Disorders, John Kostyak, Steven Mckenzie, Ulhas Naik

Cardeza Foundation for Hematologic Research

Apoptosis signal-regulating kinase 1 (ASK1) is a serine-threonine kinase that is ubiquitously expressed in nucleated cells and is responsible for the activation of multiple mitogen-activated protein kinases (MAPK) to regulate cell stress. Activation of ASK1 via cellular stress leads to activation of downstream signaling components, activation of transcription factors, and proinflammatory cytokine production. ASK1 is also expressed in anucleate platelets and is a key player in platelet activation as it is important for signaling. Interestingly, the mechanism of ASK1 activation is cell type-dependent. In this review we will explore how ASK1 regulates a variety of cellular processes from innate immune …

Species Differences In Platelet Protease-Activated Receptors, Stephanie A Renna, Steven E. Mckenzie, James V. Michael

Cardeza Foundation for Hematologic Research

Protease-activated receptors (PARs) are a class of integral membrane proteins that are cleaved by a variety of proteases, most notably thrombin, to reveal a tethered ligand and promote activation. PARs are critical mediators of platelet function in hemostasis and thrombosis, and therefore are attractive targets for anti-platelet therapies. Animal models studying platelet PAR physiology have relied heavily on genetically modified mouse strains, which have provided ample insight but have some inherent limitations. The current review aims to summarize the notable PAR expression and functional differences between the mouse and human, in addition to highlighting some recently developed tools to further …

Grk2 Regulates Adp Signaling In Platelets Via P2y1 And P2y12., Xuefei Zhao, Matthew Cooper, James V Michael, Yanki Yarman, Aiden Baltz, J Kurt Chuprun, Walter J Koch, Steven E. Mckenzie, Maurizio Tomaiuolo, Timothy J Stalker, Li Zhu, Peisong Ma

Department of Medicine Faculty Papers

The critical role of G protein-coupled receptor kinase 2 (GRK2) in regulating cardiac function has been well documented for >3 decades. Targeting GRK2 has therefore been extensively studied as a novel approach to treating cardiovascular disease. However, little is known about its role in hemostasis and thrombosis. We provide here the first evidence that GRK2 limits platelet activation and regulates the hemostatic response to injury. Deletion of GRK2 in mouse platelets causes increased platelet accumulation after laser-induced injury in the cremaster muscle arterioles, shortens tail bleeding time, and enhances thrombosis in adenosine 5'-diphosphate (ADP)-induced pulmonary thromboembolism and in FeCl3-induced carotid …

G Protein-Coupled Receptor Kinase 5 Regulates Thrombin Signaling In Platelets Via Par-1., Kate Downes, Xuefei Zhao, Nicholas S Gleadall, Harriet Mckinney, Carly Kempster, Joana Batista, Patrick L Thomas, Matthew Cooper, James V Michael, Roman Kreuzhuber, Katherine Wedderburn, Kathryn Waller, Bianca Varney, Hippolyte Verdier, Neline Kriek, Sofie E Ashford, Kathleen E Stirrups, Joanne L Dunster, Steven E Mckenzie, Willem H Ouwehand, Jonathan M Gibbins, Jing Yang, William J Astle, Peisong Ma

Cardeza Foundation for Hematologic Research

The interindividual variation in the functional response of platelets to activation by agonists is heritable. Genome-wide association studies (GWASs) of quantitative measures of platelet function have identified fewer than 20 distinctly associated variants, some with unknown mechanisms. Here, we report GWASs of pathway-specific functional responses to agonism by adenosine 5'-diphosphate, a glycoprotein VI-specific collagen mimetic, and thrombin receptor-agonist peptides, each specific to 1 of the G protein-coupled receptors PAR-1 and PAR-4, in subsets of 1562 individuals. We identified an association (P = 2.75 × 10-40) between a common intronic variant, rs10886430, in the G protein-coupled receptor kinase 5 gene (GRK5) …

The Roles Of Grks In Hemostasis And Thrombosis, Xi Chen, Xuefei Zhao, Matthew Cooper, Peisong Ma

Department of Medicine Faculty Papers

Along with cancer, cardiovascular and cerebrovascular diseases remain by far the most common causes of death. Heart attacks and strokes are diseases in which platelets play a role, through activation on ruptured plaques and subsequent thrombus formation. Most platelet agonists activate platelets via G protein-coupled receptors (GPCRs), which make these receptors ideal targets for many antiplatelet drugs. However, little is known about the mechanisms that provide feedback regulation on GPCRs to limit platelet activation. Emerging evidence from our group and others strongly suggests that GPCR kinases (GRKs) are critical negative regulators during platelet activation and thrombus formation. In this review, …

Racial Differences In Human Platelet Par4 Reactivity Reflect Expression Of Pctp And Mir-376c., Leonard Edelstein, Lukas M Simon, Raúl Teruel Montoya, Michael Holinstat, Edward S Chen, Angela Bergeron, Xianguo Kong, Srikanth Nagalla, Narla Mohandas, David E Cohen, Jing-Fei Dong, Chad Shaw, Paul Bray

Cardeza Foundation for Hematologic Research

Racial differences in the pathophysiology of atherothrombosis are poorly understood. We explored the function and transcriptome of platelets in healthy black (n = 70) and white (n = 84) subjects. Platelet aggregation and calcium mobilization induced by the PAR4 thrombin receptor were significantly greater in black subjects. Numerous differentially expressed RNAs were associated with both race and PAR4 reactivity, including PCTP (encoding phosphatidylcholine transfer protein), and platelets from black subjects expressed higher levels of PC-TP protein. PC-TP inhibition or depletion blocked PAR4- but not PAR1-mediated activation of platelets and megakaryocytic cell lines. miR-376c levels were differentially expressed by race and …

The Complex Transcriptional Landscape Of The Anucleate Human Platelet., Paul F. Bray, Steven E. Mckenzie, Leonard Edelstein, Srikanth Nagalla, Kathleen Delgrosso, Adam Ertel, Joan Kupper, Yi Jing, Eric R. Londin, Phillipe Loher, Huang-Wen Chen, Paolo Fortina, Isidore Rigoutsos

Cardeza Foundation for Hematologic Research

BACKGROUND: Human blood platelets are essential to maintaining normal hemostasis, and platelet dysfunction often causes bleeding or thrombosis. Estimates of genome-wide platelet RNA expression using microarrays have provided insights to the platelet transcriptome but were limited by the number of known transcripts. The goal of this effort was to deep-sequence RNA from leukocyte-depleted platelets to capture the complex profile of all expressed transcripts.

RESULTS: From each of four healthy individuals we generated long RNA (≥40 nucleotides) profiles from total and ribosomal-RNA depleted RNA preparations, as well as short RNA (<40 >nucleotides) profiles. Analysis of ~1 billion reads revealed that coding …

Transfection Of Human Platelets With Short Interfering Rna., Wei Hong, Altaf A Kondkar, Srikanth Nagalla, Wolfgang Bergmeier, Ying Jin, Jay Herman, Paul Bray

Cardeza Foundation for Hematologic Research

Platelets contain mRNAs and are capable of translating mRNA into protein, and it has been previously demonstrated that platelets increase their levels of integrin β3 overtime while in blood bank storage conditions. We are unaware of prior attempts to introduce nucleic acids into platelets. Considering the potential clinical and research utility of manipulating platelet gene expression, we tested whether small interfering RNAs (siRNAs) could be transfected into normal human platelets. Multiple conditions were tested, including lipofectamine versus electroporation, different amounts of siRNA, the effect of different buffers and the presence of plasma during transfection, and the time for optimal siRNA …

Integrin-Dependent Control Of Translation: Engagement Of Integrin Alphaiibbeta3 Regulates Synthesis Of Proteins In Activated Human Platelets., Ravinder Pabla, Andrew S. Weyrich, Dan A. Dixon, Paul F. Bray, Thomas M. Mcintyre, Stephen M. Prescott, Guy A. Zimmerman

Cardeza Foundation for Hematologic Research

Integrins are widely expressed plasma membrane adhesion molecules that tether cells to matrix proteins and to one another in cell-cell interactions. Integrins also transmit outside-in signals that regulate functional responses of cells, and are known to influence gene expression by regulating transcription. In previous studies we found that platelets, which are naturally occurring anucleate cytoplasts, translate preformed mRNA transcripts when they are activated by outside-in signals. Using strategies that interrupt engagement of integrin alphaIIbbeta3 by fibrinogen and platelets deficient in this integrin, we found that alphaIIbbeta3 regulates the synthesis of B cell lymphoma 3 (Bcl-3) when platelet aggregation is induced …

Physical Linkage Of The Genes For Platelet Membrane Glycoproteins Iib And Iiia., Paul F. Bray, Greg Barsh, Jean-Philippe Rosa, Xue Ya Luo, Ellen Magenis, Marc A. Shuman

Cardeza Foundation for Hematologic Research

The fibrinogen receptor on human platelets is a prototypic member of the integrin family and is composed of subunit glycoproteins IIb (gpIIb) and IIIa (gpIIIa) in a 1:1 stoichiometric ratio. We have isolated cDNA clones for gpIIb and gpIIIa and localized both genes to chromosome 17. In the current study, several approaches were used to localize and map the genes for gpIIb and gpIIIa. A preliminary evaluation of subchromosomal localization was performed by using a panel of mouse-human somatic cell hybrids that contain different amounts of the long arm of human chromosome 17. Southern hybridization to the DNA of these …