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The Proteasome Inhibitor Bortezomib Induces Apoptosis and Activation in Gel-Filtered Human Platelets. Int J Mol Sci 2021; 22:ijms22168955. [PMID: 34445660 PMCID: PMC8396574 DOI: 10.3390/ijms22168955] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2021] [Revised: 08/17/2021] [Accepted: 08/17/2021] [Indexed: 11/16/2022] Open
Abstract
Bortezomib (BTZ) has demonstrated its efficacy in several hematological disorders and has been associated with thrombocytopenia. There is controversy about the effect of BTZ on human platelets, so we set out to determine its effect on various types of platelet samples. Human platelets were investigated in platelet-rich plasma (PRP) and as gel-filtered platelets (GFPs). Mitochondrial inner membrane potential depolarization and phosphatidylserine (PS) and P-selectin expression levels were studied by flow cytometry, while thrombin generation was measured by a fluorescent method. In PRP, BTZ caused negligible PS expression after 60 min of treatment. However, in GFPs, PS expression was dose- and time-dependently increased in the BTZ-treated groups, as was P-selectin. The percentage of depolarized cells was also higher after BTZ pretreatment at both time points. Peak thrombin and velocity index increased significantly even with the lowest BTZ concentration (p = 0.0019; p = 0.0032) whereas time to peak and start tail parameters decreased (p = 0.0007; p = 0.0034). The difference between PRP and GFP results can be attributed to the presence of plasma proteins in PRP, as the PS-stimulating effect of BTZ could be attenuated by supplementing GFPs with purified human albumin. Overall, BTZ induces a procoagulant platelet phenotype in an experimental setting devoid of plasma proteins.
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Colberg L, Cammann C, Wesche J, Topfstedt E, Seifert U, Greinacher A. The platelet proteasome and immunoproteasome are stable in buffy-coat derived platelet concentrates for up to 7 days. Transfusion 2021; 61:2746-2755. [PMID: 34331776 DOI: 10.1111/trf.16605] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2020] [Revised: 06/20/2021] [Accepted: 06/27/2021] [Indexed: 01/19/2023]
Abstract
OBJECTIVES Characterization of the proteasome and its stability in buffy-coat derived platelet concentrates (PCs) during storage. BACKGROUND The proteasome plays a key role in cell homeostasis by processing misfolded or abnormal proteins and regulating the levels and activities of a high number of proteins contributing to cell cycle, survival, and proliferation. Controversial data exist, whether inhibition of the proteasome affects platelet function. Little is known about function, expression, and stability of the proteasome in PCs during storage, and the potential role of the platelet proteasome in storage lesions. STUDY DESIGN AND METHODS PCs were produced by the buffy-coat method in additive solution and stored at room temperature under agitation. Platelet aggregation was monitored by light transmission aggregometry. Proteasome complexes were assessed by immunoprecipitation and immunoblotting, and proteasome activity was measured using fluorogenic substrates specific for the three different proteolytic activities over 7 days of storage. RESULTS Proteasome inhibition led to a decreased platelet aggregation response after activation with collagen, ADP, TRAP-6, and thrombin. There were no changes in the expression of the catalytic active subunits as well as the proteasome activity during storage of PCs, comparing baseline and day 7. DISCUSSION Platelet proteasome function is relevant for platelet aggregation in response to various agonists. The constitutive and stable expression of the active standard- and immunoproteasome in platelets makes it unlikely that loss of proteasome function is a relevant cause of storage lesions.
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Affiliation(s)
- Lisa Colberg
- Institut für Immunologie und Transfusionsmedizin, Universitätsmedizin Greifswald, Greifswald, Germany.,Friedrich Loeffler-Institut für Medizinische Mikrobiologie-Virologie, Universitätsmedizin Greifswald, Greifswald, Germany
| | - Clemens Cammann
- Friedrich Loeffler-Institut für Medizinische Mikrobiologie-Virologie, Universitätsmedizin Greifswald, Greifswald, Germany
| | - Jan Wesche
- Institut für Immunologie und Transfusionsmedizin, Universitätsmedizin Greifswald, Greifswald, Germany
| | - Eylin Topfstedt
- Friedrich Loeffler-Institut für Medizinische Mikrobiologie-Virologie, Universitätsmedizin Greifswald, Greifswald, Germany
| | - Ulrike Seifert
- Friedrich Loeffler-Institut für Medizinische Mikrobiologie-Virologie, Universitätsmedizin Greifswald, Greifswald, Germany
| | - Andreas Greinacher
- Institut für Immunologie und Transfusionsmedizin, Universitätsmedizin Greifswald, Greifswald, Germany
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El-Kadiry AEH, Merhi Y. The Role of the Proteasome in Platelet Function. Int J Mol Sci 2021; 22:ijms22083999. [PMID: 33924425 PMCID: PMC8069084 DOI: 10.3390/ijms22083999] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2021] [Revised: 04/06/2021] [Accepted: 04/08/2021] [Indexed: 02/06/2023] Open
Abstract
Platelets are megakaryocyte-derived acellular fragments prepped to maintain primary hemostasis and thrombosis by preserving vascular integrity. Although they lack nuclei, platelets harbor functional genomic mediators that bolster platelet activity in a signal-specific manner by performing limited de novo protein synthesis. Furthermore, despite their limited protein synthesis, platelets are equipped with multiple protein degradation mechanisms, such as the proteasome. In nucleated cells, the functions of the proteasome are well established and primarily include proteostasis among a myriad of other signaling processes. However, the role of proteasome-mediated protein degradation in platelets remains elusive. In this review article, we recapitulate the developing literature on the functions of the proteasome in platelets, discussing its emerging regulatory role in platelet viability and function and highlighting how its functional coupling with the transcription factor NF-κB constitutes a novel potential therapeutic target in atherothrombotic diseases.
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Affiliation(s)
- Abed El-Hakim El-Kadiry
- Laboratory of Thrombosis and Hemostasis, Montreal Heart Institute, Research Centre, Montreal, QC H1T 1C8, Canada;
- Biomedical Sciences Program, Faculty of Medicine, Université de Montréal, Montreal, QC H3T 1J4, Canada
| | - Yahye Merhi
- Laboratory of Thrombosis and Hemostasis, Montreal Heart Institute, Research Centre, Montreal, QC H1T 1C8, Canada;
- Biomedical Sciences Program, Faculty of Medicine, Université de Montréal, Montreal, QC H3T 1J4, Canada
- Correspondence: ; Tel.: +1-514-376-3330
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Klingler P, Niklaus M, Koessler J, Weber K, Koessler A, Boeck M, Kobsar A. Influence of long-term proteasome inhibition on platelet responsiveness mediated by bortezomib. Vascul Pharmacol 2021; 138:106830. [PMID: 33422688 DOI: 10.1016/j.vph.2021.106830] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2020] [Revised: 12/28/2020] [Accepted: 01/04/2021] [Indexed: 12/24/2022]
Abstract
INTRODUCTION Although platelets contain a full proteasome system, its role in platelet function is not completely understood yet. Since the proteasome system may be involved in time-delayed processes, platelet responsiveness was investigated after long-term, bortezomib-mediated proteasome inhibition. MATERIALS AND METHODS Citrate-anticoagulated whole blood was stored with 5 nM and 1 μM bortezomib for 24 h. Consecutively, aggregation was measured by light transmission in platelet-rich-plasma (PRP). Flow cytometry was performed to determine phosphorylation levels of the vasodilator-stimulated phosphoprotein (VASP), fibrinogen binding, PAC1-antibody binding and purinergic receptor expression in PRP, P2Y12 activity or glycoprotein (GP) Ib and IIb expression in whole blood. P2Y1 and P2X1 activities were assessed by calcium flux-induced fluorescence in washed platelets. Using PRP, adherent platelets on fibrinogen-, collagen- and ristocetin-coated surfaces were visualized and quantified by immunostaining. RESULTS Under bortezomib, VASP phosphorylation was less inducible and nitric oxide-induced inhibition of fibrinogen binding was slightly reduced. Proteasome inhibition did not tamper adenosine diphosphate-mediated aggregation or purinergic receptor expression and activity. Induced expression of activated fibrinogen receptors and fibrinogen binding were not significantly influenced by incubation with bortezomib for 24 h. Aggregation values with threshold agonist concentrations were increased under bortezomib. Despite unchanged GPIb expression, bortezomib-treated platelets showed enhanced adhesion on coated surfaces. CONCLUSIONS In platelets incubated for 24 h, bortezomib mediates a slight attenuation of inhibitory signaling, associated with facilitated platelet aggregation using threshold agonist concentrations and enhanced adhesion on agonist-coated surfaces.
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Affiliation(s)
- Philipp Klingler
- Institute of Transfusion Medicine and Haemotherapy, University of Wuerzburg, Oberduerrbacher Straße 6, D-97080 Wuerzburg, Germany.
| | - Marius Niklaus
- Institute of Transfusion Medicine and Haemotherapy, University of Wuerzburg, Oberduerrbacher Straße 6, D-97080 Wuerzburg, Germany.
| | - Juergen Koessler
- Institute of Transfusion Medicine and Haemotherapy, University of Wuerzburg, Oberduerrbacher Straße 6, D-97080 Wuerzburg, Germany.
| | - Katja Weber
- Institute of Transfusion Medicine and Haemotherapy, University of Wuerzburg, Oberduerrbacher Straße 6, D-97080 Wuerzburg, Germany.
| | - Angela Koessler
- Institute of Transfusion Medicine and Haemotherapy, University of Wuerzburg, Oberduerrbacher Straße 6, D-97080 Wuerzburg, Germany.
| | - Markus Boeck
- Institute of Transfusion Medicine and Haemotherapy, University of Wuerzburg, Oberduerrbacher Straße 6, D-97080 Wuerzburg, Germany.
| | - Anna Kobsar
- Institute of Transfusion Medicine and Haemotherapy, University of Wuerzburg, Oberduerrbacher Straße 6, D-97080 Wuerzburg, Germany.
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Colberg L, Cammann C, Greinacher A, Seifert U. Structure and function of the ubiquitin-proteasome system in platelets. J Thromb Haemost 2020; 18:771-780. [PMID: 31898400 DOI: 10.1111/jth.14730] [Citation(s) in RCA: 25] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2019] [Accepted: 12/30/2019] [Indexed: 12/16/2022]
Abstract
Platelets are small anucleate blood cells with a life span of 7 to 10 days. They are main regulators of hemostasis. Balanced platelet activity is crucial to prevent bleeding or occlusive thrombus formation. Growing evidence supports that platelets also participate in immune reactions, and interaction between platelets and leukocytes contributes to both thrombosis and inflammation. The ubiquitin-proteasome system (UPS) plays a key role in maintaining cellular protein homeostasis by its ability to degrade non-functional self-, foreign, or short-lived regulatory proteins. Platelets express standard and immunoproteasomes. Inhibition of the proteasome impairs platelet production and platelet function. Platelets also express major histocompatibility complex (MHC) class I molecules. Peptide fragments released by proteasomes can bind to MHC class I, which makes it also likely that platelets can activate epitope specific cytotoxic T lymphocytes (CTLs). In this review, we focus on current knowledge on the significance of the proteasome for the functions of platelets as critical regulators of hemostasis as well as modulators of the immune response.
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Affiliation(s)
- Lisa Colberg
- Friedrich Loeffler Institut für Medizinische Mikrobiologie-Virologie, Universitätsmedizin Greifswald, Greifswald, Germany
- Institut für Immunologie und Transfusionsmedizin, Universitätsmedizin Greifswald, Greifswald, Germany
| | - Clemens Cammann
- Friedrich Loeffler Institut für Medizinische Mikrobiologie-Virologie, Universitätsmedizin Greifswald, Greifswald, Germany
| | - Andreas Greinacher
- Institut für Immunologie und Transfusionsmedizin, Universitätsmedizin Greifswald, Greifswald, Germany
| | - Ulrike Seifert
- Friedrich Loeffler Institut für Medizinische Mikrobiologie-Virologie, Universitätsmedizin Greifswald, Greifswald, Germany
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Koessler J, Schuepferling A, Klingler P, Koessler A, Weber K, Boeck M, Kobsar A. The role of proteasome activity for activating and inhibitory signalling in human platelets. Cell Signal 2019; 62:109351. [PMID: 31260799 DOI: 10.1016/j.cellsig.2019.109351] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2019] [Revised: 06/24/2019] [Accepted: 06/25/2019] [Indexed: 11/29/2022]
Abstract
Platelets express key proteins of the proteasome system, but its functional role in the regulation of platelet integrity, however, is not fully understood yet. Therefore, this study evaluated activating and inhibitory platelet signalling pathways using the potent and selective proteasome inhibitor bortezomib. In washed platelets, the effect of bortezomib on viability and on aggregation was assessed. In addition, fibrinogen binding and CD62P expression were determined. The influence on activating and inhibitory signalling was detected by phosphorylation levels of essential messenger molecules. Platelet viability was maintained after incubation with 0.01 μM to 1 μM bortezomib, but tampered with 100 μM bortezomib. Agonist-induced aggregation was only reduced under 100 μM bortezomib and with weak induction by 10 μM adenosine diphosphate. Similarly, phosphorylated kinase levels of the activating signalling pathways were not affected by 0.01 μM to 1 μM bortezomib. In contrast, proteasome inhibition resulted in the reduction of inhibitor-induced vasodilator-stimulated phosphoprotein phosphorylation, accompanied with the partial decrease of induced inhibition of fibrinogen binding and CD62P expression. In conclusion, platelet activation and aggregation are not dependent on proteasome activity. Instead, inhibitory signalling is partially attenuated under proteasome inhibition. Supramaximal inhibitory concentrations of bortezomib (above 1 μM) lead to heterogeneous effects on activating or inhibitory systems, probably caused by decreasing platelet viability.
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Affiliation(s)
- Juergen Koessler
- Institute of Transfusion Medicine and Haemotherapy, University of Wuerzburg, Oberduerrbacher Straße 6, D-97080 Wuerzburg, Germany.
| | - Anne Schuepferling
- Institute of Transfusion Medicine and Haemotherapy, University of Wuerzburg, Oberduerrbacher Straße 6, D-97080 Wuerzburg, Germany
| | - Philipp Klingler
- Institute of Transfusion Medicine and Haemotherapy, University of Wuerzburg, Oberduerrbacher Straße 6, D-97080 Wuerzburg, Germany.
| | - Angela Koessler
- Institute of Transfusion Medicine and Haemotherapy, University of Wuerzburg, Oberduerrbacher Straße 6, D-97080 Wuerzburg, Germany.
| | - Katja Weber
- Institute of Transfusion Medicine and Haemotherapy, University of Wuerzburg, Oberduerrbacher Straße 6, D-97080 Wuerzburg, Germany.
| | - Markus Boeck
- Institute of Transfusion Medicine and Haemotherapy, University of Wuerzburg, Oberduerrbacher Straße 6, D-97080 Wuerzburg, Germany.
| | - Anna Kobsar
- Institute of Transfusion Medicine and Haemotherapy, University of Wuerzburg, Oberduerrbacher Straße 6, D-97080 Wuerzburg, Germany.
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