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Amalia M, Puteri MU, Saputri FC, Sauriasari R, Widyantoro B. Platelet Glycoprotein-Ib (GPIb) May Serve as a Bridge between Type 2 Diabetes Mellitus (T2DM) and Atherosclerosis, Making It a Potential Target for Antiplatelet Agents in T2DM Patients. Life (Basel) 2023; 13:1473. [PMID: 37511848 PMCID: PMC10381765 DOI: 10.3390/life13071473] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2023] [Revised: 06/23/2023] [Accepted: 06/26/2023] [Indexed: 07/30/2023] Open
Abstract
Type 2 diabetes mellitus (T2DM) is a persistent metabolic condition that contributes to the development of cardiovascular diseases. Numerous studies have provided evidence that individuals with T2DM are at a greater risk of developing cardiovascular diseases, typically two to four times more likely than those without T2DM, mainly due to an increased risk of atherosclerosis. The rupture of an atherosclerotic plaque leading to pathological thrombosis is commonly recognized as a significant factor in advancing cardiovascular diseases caused by TD2M, with platelets inducing the impact of plaque rupture in established atherosclerosis and predisposing to the primary expansion of atherosclerosis. Studies suggest that individuals with T2DM have platelets that display higher baseline activation and reactivity than those without the condition. The expression enhancement of several platelet receptors is known to regulate platelet activation signaling, including platelet glycoprotein-Ib (GPIb). Furthermore, the high expression of platelet GP1b has been reported to increase the risk of platelet adhesion, platelet-leucocyte interaction, and thrombo-inflammatory pathology. However, the study exploring the role of GP1b in promoting platelet activation-induced cardiovascular diseases in T2DM patients is still limited. Therefore, we summarize the important findings regarding pathophysiological continuity between T2DM, platelet GPIb, and atherosclerosis and highlight the potential therapy targeting GPIb as a novel antiplatelet agent for preventing further cardiovascular incidents in TD2M patients.
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Affiliation(s)
- Muttia Amalia
- Doctoral Program, Faculty of Pharmacy, Universitas Indonesia, Kampus UI Depok, Depok 16424, Indonesia
| | - Meidi Utami Puteri
- Laboratory of Pharmacology-Toxicology, Faculty of Pharmacy, Universitas Indonesia, Kampus UI Depok, Depok 16424, Indonesia
| | - Fadlina Chany Saputri
- Laboratory of Pharmacology-Toxicology, Faculty of Pharmacy, Universitas Indonesia, Kampus UI Depok, Depok 16424, Indonesia
| | - Rani Sauriasari
- Faculty of Pharmacy, Universitas Indonesia, Kampus UI Depok, Depok 16424, Indonesia
| | - Bambang Widyantoro
- National Cardiovascular Center Harapan Kita, Department of Cardiology and Vascular Medicine, Faculty of Medicine, Universitas Indonesia, Jakarta 11420, Indonesia
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Tsai HJ, Cheng JC, Kao ML, Chiu HP, Chiang YH, Chen DP, Rau KM, Liao HR, Tseng CP. Integrin αIIbβ3 outside-in signaling activates human platelets through serine 24 phosphorylation of Disabled-2. Cell Biosci 2021; 11:32. [PMID: 33557943 PMCID: PMC7869483 DOI: 10.1186/s13578-021-00532-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2020] [Accepted: 01/05/2021] [Indexed: 11/29/2022] Open
Abstract
Background Bidirectional integrin αIIbβ3 signaling is essential for platelet activation. The platelet adaptor protein Disabled-2 (Dab2) is a key regulator of integrin signaling and is phosphorylated at serine 24 in eukaryotic cells. However, the mechanistic insight and function of Dab2-serine 24 phosphorylation (Dab2-pSer24) in platelet biology are barely understood. This study aimed to define whether and how Dab2 is phosphorylated at Ser24 during platelet activation and to investigate the effect of Dab2-pSer24 on platelet function. Results An antibody with confirmed specificity for Dab2-pSer24 was generated. By using this antibody as a tool, we showed that protein kinase C (PKC)-mediated Dab2-pSer24 was a conservative signaling event when human platelets were activated by the platelet agonists such as thrombin, collagen, ADP, 12-O-tetradecanoylphorbol-13-acetate, and the thromboxane A2 activator U46619. The agonists-stimulated Dab2-pSer24 was attenuated by pretreatment of platelets with the RGDS peptide which inhibits integrin outside-in signaling by competitive binding of integrin αIIb with fibrinogen. Direct activation of platelet integrin outside-in signaling by combined treatment of platelets with manganese dichloride and fibrinogen or by spreading of platelets on fibrinogen also resulted in Dab2-pSer24. These findings implicate that Dab2-pSer24 was associated with the outside-in signaling of integrin. Further analysis revealed that Dab2-pSer24 was downstream of Src-PKC-axis and phospholipase D1 underlying the integrin αIIbβ3 outside-in signaling. A membrane penetrating peptide R11-Ser24 which contained 11 repeats of arginine linked to the Dab2-Ser24 phosphorylation site and its flanking sequences (RRRRRRRRRRR19APKAPSKKEKK29) and the R11-S24A peptide with Ser24Ala mutation were designed to elucidate the functions of Dab2-pSer24. R11-Ser24 but not R11-S24A inhibited agonists-stimulated Dab2-pSer24 and consequently suppressed platelet spreading on fibrinogen, with no effect on platelet aggregation and fibrinogen binding. Notably, Ser24 and the previously reported Ser723 phosphorylation (Dab2-pSer723) occurred exclusively in a single Dab2 molecule and resulted in distinctive subcellular distribution and function of Dab2. Dab2-pSer723 was mainly distributed in the cytosol of activated platelets and associated with integrin inside-out signaling, while Dab2-pSer24 was mainly distributed in the membrane fraction of activated platelets and associated with integrin outside-in signaling. Conclusions These findings demonstrate for the first time that Dab2-pSer24 is conservative in integrin αIIbβ3 outside-in signaling during platelet activation and plays a novel role in the control of cytoskeleton reorganization and platelet spreading on fibrinogen.
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Affiliation(s)
- Hui-Ju Tsai
- Department of Medical Biotechnology and Laboratory Science, College of Medicine, Chang Gung University, Taoyuan, 333, Taiwan, Republic of China
| | - Ju-Chien Cheng
- Department of Medical Laboratory Science and Biotechnology, China Medical University, Taichung, 404, Taiwan, Republic of China
| | - Man-Leng Kao
- Department of Medical Biotechnology and Laboratory Science, College of Medicine, Chang Gung University, Taoyuan, 333, Taiwan, Republic of China
| | - Hung-Pin Chiu
- Department of Medical Biotechnology and Laboratory Science, College of Medicine, Chang Gung University, Taoyuan, 333, Taiwan, Republic of China
| | - Yi-Hsuan Chiang
- Department of Medical Biotechnology and Laboratory Science, College of Medicine, Chang Gung University, Taoyuan, 333, Taiwan, Republic of China
| | - Ding-Ping Chen
- Department of Medical Biotechnology and Laboratory Science, College of Medicine, Chang Gung University, Taoyuan, 333, Taiwan, Republic of China.,Department of Laboratory Medicine, Chang Gung Memorial Hospital, Taoyuan, 333, Taiwan, Republic of China
| | - Kun-Ming Rau
- Department of Hematology-Oncology, E-Da Cancer Hospital, Kaohsiung, 824, Taiwan, Republic of China.,School of Medicine, College of Medicine, I-Shou University, Kaohsiung, 824, Taiwan, Republic of China
| | - Hsiang-Ruei Liao
- Graduate institute of Natural Products, College of Medicine, Chang-Gung University, Taoyuan, 333, Taiwan, Republic of China.,Graduate institute of Biomedical Sciences, College of Medicine, Chang Gung University, Taoyuan, 333, Taiwan, Republic of China.,Department of Anesthesiology, Chang Gung Memorial Hospital, Taoyuan, 333, Taiwan, Republic of China
| | - Ching-Ping Tseng
- Department of Medical Biotechnology and Laboratory Science, College of Medicine, Chang Gung University, Taoyuan, 333, Taiwan, Republic of China. .,Department of Laboratory Medicine, Chang Gung Memorial Hospital, Taoyuan, 333, Taiwan, Republic of China. .,Graduate institute of Biomedical Sciences, College of Medicine, Chang Gung University, Taoyuan, 333, Taiwan, Republic of China. .,Molecular Medicine Research Center, Chang Gung University, Taoyuan, 333, Taiwan, Republic of China.
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Ohno Y, Suzuki-Takedachi K, Yasunaga S, Kurogi T, Santo M, Masuhiro Y, Hanazawa S, Ohtsubo M, Naka K, Takihara Y. Manipulation of Cell Cycle and Chromatin Configuration by Means of Cell-Penetrating Geminin. PLoS One 2016; 11:e0155558. [PMID: 27195810 PMCID: PMC4873132 DOI: 10.1371/journal.pone.0155558] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2015] [Accepted: 04/29/2016] [Indexed: 02/02/2023] Open
Abstract
Geminin regulates chromatin remodeling and DNA replication licensing which play an important role in regulating cellular proliferation and differentiation. Transcription of the Geminin gene is regulated via an E2F-responsive region, while the protein is being closely regulated by the ubiquitin-proteasome system. Our objective was to directly transduce Geminin protein into cells. Recombinant cell-penetrating Geminin (CP-Geminin) was generated by fusing Geminin with a membrane translocating motif from FGF4 and was efficiently incorporated into NIH 3T3 cells and mouse embryonic fibroblasts. The withdrawal study indicated that incorporated CP-Geminin was quickly reduced after removal from medium. We confirmed CP-Geminin was imported into the nucleus after incorporation and also that the incorporated CP-Geminin directly interacted with Cdt1 or Brahma/Brg1 as the same manner as Geminin. We further demonstrated that incorporated CP-Geminin suppressed S-phase progression of the cell cycle and reduced nuclease accessibility in the chromatin, probably through suppression of chromatin remodeling, indicating that CP-Geminin constitutes a novel tool for controlling chromatin configuration and the cell cycle. Since Geminin has been shown to be involved in regulation of stem cells and cancer cells, CP-Geminin is expected to be useful for elucidating the role of Geminin in stem cells and cancer cells, and for manipulating their activity.
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Affiliation(s)
- Yoshinori Ohno
- Department of Stem Cell Biology, Research Institute for Radiation Biology and Medicine, Hiroshima University, Kasumi, Minami-ku, Hiroshima, Japan
| | - Kyoko Suzuki-Takedachi
- Department of Stem Cell Biology, Research Institute for Radiation Biology and Medicine, Hiroshima University, Kasumi, Minami-ku, Hiroshima, Japan
| | - Shin’ichiro Yasunaga
- Department of Stem Cell Biology, Research Institute for Radiation Biology and Medicine, Hiroshima University, Kasumi, Minami-ku, Hiroshima, Japan
- Department of Biochemistry, Faculty of Medicine, Fukuoka University, Nanakuma, Jonan-ku, Fukuoka, Japan
| | - Toshiaki Kurogi
- Department of Stem Cell Biology, Research Institute for Radiation Biology and Medicine, Hiroshima University, Kasumi, Minami-ku, Hiroshima, Japan
| | - Mimoko Santo
- Department of Stem Cell Biology, Research Institute for Radiation Biology and Medicine, Hiroshima University, Kasumi, Minami-ku, Hiroshima, Japan
| | - Yoshikazu Masuhiro
- Department of Applied Biological Sciences, College of Bioresource Sciences, Nihon University, Kameino, Fujisawa-city, Kanagawa, Japan
| | - Shigemasa Hanazawa
- Department of Applied Biological Sciences, College of Bioresource Sciences, Nihon University, Kameino, Fujisawa-city, Kanagawa, Japan
| | - Motoaki Ohtsubo
- Department of Food and Fermentation Science, Faculty of Food Science and Nutrition, Beppu University, Kita-ishigaki 82, Beppu-city, Oita, Japan
| | - Kazuhito Naka
- Department of Stem Cell Biology, Research Institute for Radiation Biology and Medicine, Hiroshima University, Kasumi, Minami-ku, Hiroshima, Japan
| | - Yoshihiro Takihara
- Department of Stem Cell Biology, Research Institute for Radiation Biology and Medicine, Hiroshima University, Kasumi, Minami-ku, Hiroshima, Japan
- * E-mail:
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Bialkowska K, Byzova TV, Plow EF. Site-specific phosphorylation of kindlin-3 protein regulates its capacity to control cellular responses mediated by integrin αIIbβ3. J Biol Chem 2015; 290:6226-42. [PMID: 25609252 DOI: 10.1074/jbc.m114.634436] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The contributions of integrins to cellular responses depend upon their activation, which is regulated by binding of proteins to their cytoplasmic tails. Kindlins are integrin cytoplasmic tail binding partners and are essential for optimal integrin activation, and kindlin-3 fulfills this role in hematopoietic cells. Here, we used human platelets and human erythroleukemia (HEL) cells, which express integrin αIIbβ3, to investigate whether phosphorylation of kindlin-3 regulates integrin activation. When HEL cells were stimulated with thrombopoietin or phorbol 12-myristate 13-acetate (PMA), αIIbβ3 became activated as evidenced by binding of an activation-specific monoclonal antibody and soluble fibrinogen, adherence and spreading on fibrinogen, colocalization of β3 integrin and kindlin-3 in focal adhesions, and enhanced β3 integrin-kindlin-3 association in immunoprecipitates. Kindlin-3 knockdown impaired adhesion and spreading on fibrinogen. Stimulation of HEL cells with agonists significantly increased kindlin-3 phosphorylation as detected by mass spectrometric sequencing. Thr(482) or Ser(484) was identified as a phosphorylation site, which resides in a sequence not conserved in kindlin-1 or kindlin-2. These same residues were phosphorylated in kindlin-3 when platelets were stimulated with thrombin. When expressed in HEL cells, T482A/S484A kindlin-3 decreased soluble ligand binding and cell spreading on fibrinogen compared with wild-type kindlin-3. A membrane-permeable peptide containing residues 476-485 of kindlin-3 was introduced into HEL cells and platelets; adhesion and spreading of both cell types were blunted compared with a scrambled control peptide. These data identify a role of kindlin-3 phosphorylation in integrin β3 activation and provide a basis for functional differences between kindlin-3 and the two other kindlin paralogs.
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Affiliation(s)
- Katarzyna Bialkowska
- From the Joseph J. Jacobs Center for Thrombosis and Vascular Biology, Department of Molecular Cardiology, Lerner Research Institute, Cleveland Clinic, Cleveland, Ohio 44195
| | - Tatiana V Byzova
- From the Joseph J. Jacobs Center for Thrombosis and Vascular Biology, Department of Molecular Cardiology, Lerner Research Institute, Cleveland Clinic, Cleveland, Ohio 44195
| | - Edward F Plow
- From the Joseph J. Jacobs Center for Thrombosis and Vascular Biology, Department of Molecular Cardiology, Lerner Research Institute, Cleveland Clinic, Cleveland, Ohio 44195
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5
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Bender M, May F, Lorenz V, Thielmann I, Hagedorn I, Finney BA, Vögtle T, Remer K, Braun A, Bösl M, Watson SP, Nieswandt B. Combined in vivo depletion of glycoprotein VI and C-type lectin-like receptor 2 severely compromises hemostasis and abrogates arterial thrombosis in mice. Arterioscler Thromb Vasc Biol 2013; 33:926-34. [PMID: 23448972 DOI: 10.1161/atvbaha.112.300672] [Citation(s) in RCA: 96] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
OBJECTIVE Platelet inhibition is a major strategy to prevent acute ischemic cardiovascular and cerebrovascular events, which may, however, be associated with an increased bleeding risk. The (hem)immunoreceptor tyrosine activation motif-bearing platelet receptors, glycoprotein VI (GPVI) and C-type lectin-like receptor 2 (CLEC-2), might be promising antithrombotic targets because they can be depleted from circulating platelets by antibody treatment, leading to sustained antithrombotic protection, but only moderately increased bleeding times in mice. APPROACH AND RESULTS We investigated whether both (hem)immunoreceptor tyrosine activation motif-bearing receptors can be targeted simultaneously and what the in vivo consequences of such a combined therapeutic GPVI/CLEC-2 deficiency are. We demonstrate that isolated targeting of either GPVI or CLEC-2 in vivo does not affect expression or function of the respective other receptor. Moreover, simultaneous treatment with both antibodies resulted in the sustained loss of both GPVI and CLEC-2, while leaving other activation pathways intact. However, GPVI/CLEC-2-depleted mice displayed a dramatic hemostatic defect and profound impairment of arterial thrombus formation. Furthermore, a strongly diminished hemostatic response could also be reproduced in mice genetically lacking GPVI and CLEC-2. CONCLUSIONS These results demonstrate that GPVI and CLEC-2 can be simultaneously downregulated in platelets in vivo and reveal an unexpected functional redundancy of the 2 receptors in hemostasis and thrombosis. These findings may have important implications of the potential use of anti-GPVI and anti-CLEC-2-based agents in the prevention of thrombotic diseases.
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Affiliation(s)
- Markus Bender
- University Hospital Würzburg and Rudolf Virchow Center, DFG Research Center for Experimental Biomedicine, University of Würzburg, Würzburg, Germany
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Lee H, Hamilton JR. Physiology, pharmacology, and therapeutic potential of protease-activated receptors in vascular disease. Pharmacol Ther 2012; 134:246-59. [DOI: 10.1016/j.pharmthera.2012.01.007] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2012] [Accepted: 01/17/2012] [Indexed: 01/09/2023]
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Abstract
Recent findings have identified critical roles for the actin filament-crosslinking protein filamin A (FlnA) in platelets and megakaryocytes. This short review focuses on the structure of FlnA and its interaction with the Von Willebrand Factor receptor GPIb-IX-V complex and the fibrinogen receptor, the integrin αIIbβ3 in platelets.
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Affiliation(s)
- Hervé Falet
- Division of Translational Medicine, Brigham and Women's Hospital, Department of Medicine, Harvard Medical School, Boston, MA 02115, USA
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8
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Yan R, Mo X, Paredes AM, Dai K, Lanza F, Cruz MA, Li R. Reconstitution of the platelet glycoprotein Ib-IX complex in phospholipid bilayer Nanodiscs. Biochemistry 2011; 50:10598-606. [PMID: 22080766 DOI: 10.1021/bi201351d] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
The glycoprotein Ib-IX (GPIb-IX) complex expressed on platelet plasma membrane is involved in thrombosis and hemostasis via the initiation of adhesion of platelets to von Willebrand factor (VWF) exposed at the injured vessel wall. While most of the knowledge of the GPIb-IX complex was obtained from studies on platelets and transfected mammalian cells expressing the GPIb-IX complex, there is not an in vitro membrane system that allows systematic analysis of this receptor. The phospholipid bilayer Nanodisc composed of a patch of phospholipid surrounded by membrane scaffold protein is an attractive tool for membrane protein study. We show here that the GPIb-IX complex purified from human platelets has been reconstituted into the Nanodisc. The Nanodisc-reconstituted GPIb-IX complex was able to bind various conformation-sensitive monoclonal antibodies. Furthermore, it bound to VWF in the presence of botrocetin with an apparent K(d) of 0.73 ± 0.07 nM. The binding to VWF was inhibited by anti-GPIbα antibodies with epitopes overlapping with the VWF-binding site, but not by anti-GPIbβ monoclonal antibody RAM.1. Finally, the Nanodisc-reconstituted GPIb-IX complex exhibited ligand binding activity similar to that of the isolated extracellular domain of GPIbα. In conclusion, the GPIb-IX complex in Nanodiscs adopts a native-like conformation and possesses the ability to bind its natural ligands, thus making a Nanodisc a suitable in vitro platform for further investigation of this hemostatically important receptor complex.
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Affiliation(s)
- Rong Yan
- Ministry of Health Key Laboratory of Thrombosis and Haemostasis, Jiangsu Institute of Hematology, First Affiliated Hospital of Soochow University, Suzhou, China
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Das M, Ithychanda SS, Qin J, Plow EF. Migfilin and filamin as regulators of integrin activation in endothelial cells and neutrophils. PLoS One 2011; 6:e26355. [PMID: 22043318 PMCID: PMC3197140 DOI: 10.1371/journal.pone.0026355] [Citation(s) in RCA: 56] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2011] [Accepted: 09/25/2011] [Indexed: 12/18/2022] Open
Abstract
Cell adhesion and migration depend on engagement of extracellular matrix ligands by integrins. Integrin activation is dynamically regulated by interactions of various cytoplasmic proteins, such as filamin and integrin activators, talin and kindlin, with the cytoplasmic tail of the integrin β subunit. Although filamin has been suggested to be an inhibitor of integrin activation, direct functional evidence for the inhibitory role of filamin is limited. Migfilin, a filamin-binding protein enriched at cell-cell and cell-extracellular matrix contact sites, can displace filamin from β1 and β3 integrins and promote integrin activation. However, its role in activation and functions of different β integrins in human vascular cells is unknown. In this study, using flow cytometry, we demonstrate that filamin inhibits β1 and αIIbβ3 integrin activation, and migfilin can overcome its inhibitory effect. Migfilin protein is widely expressed in different adherent and circulating blood cells and can regulate integrin activation in naturally-occurring vascular cells, endothelial cells and neutrophils. Migfilin can activate β1, β2 and β3 integrins and promote integrin mediated responses while migfilin depletion impairs the spreading and migration of endothelial cells. Thus, filamin can act broadly as an inhibitor and migfilin is a promoter of integrin activation.
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Affiliation(s)
- Mitali Das
- Department of Molecular Cardiology, Lerner Research Institute, Cleveland Clinic, Cleveland, Ohio, United States of America
| | - Sujay Subbayya Ithychanda
- Department of Molecular Cardiology, Lerner Research Institute, Cleveland Clinic, Cleveland, Ohio, United States of America
| | - Jun Qin
- Department of Molecular Cardiology, Lerner Research Institute, Cleveland Clinic, Cleveland, Ohio, United States of America
| | - Edward F. Plow
- Department of Molecular Cardiology, Lerner Research Institute, Cleveland Clinic, Cleveland, Ohio, United States of America
- * E-mail:
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FlnA-null megakaryocytes prematurely release large and fragile platelets that circulate poorly. Blood 2011; 118:2285-95. [PMID: 21652675 DOI: 10.1182/blood-2011-04-348482] [Citation(s) in RCA: 80] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
Filamin A (FlnA) is a large cytoplasmic protein that crosslinks actin filaments and anchors membrane receptors and signaling intermediates. FlnA(loxP) PF4-Cre mice that lack FlnA in the megakaryocyte (MK) lineage have a severe macrothrombocytopenia because of accelerated platelet clearance. Macrophage ablation by injection of clodronate-encapsulated liposomes increases blood platelet counts in FlnA(loxP) PF4-Cre mice and reveals the desintegration of FlnA-null platelets into microvesicles, a process that occurs spontaneously during storage. FlnA(loxP) PF4-Cre bone marrows and spleens have a 2.5- to 5-fold increase in MK numbers, indicating increased thrombopoiesis in vivo. Analysis of platelet production in vitro reveals that FlnA-null MKs prematurely convert their cytoplasm into large CD61(+) platelet-sized particles, reminiscent of the large platelets observed in vivo. FlnA stabilizes the platelet von Willebrand factor receptor, as surface expression of von Willebrand factor receptor components is normal on FlnA-null MKs but decreased on FlnA-null platelets. Further, FlnA-null platelets contain multiple GPIbα degradation products and have increased expression of the ADAM17 and MMP9 metalloproteinases. Together, the findings indicate that FlnA-null MKs prematurely release large and fragile platelets that are removed rapidly from the circulation by macrophages.
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Falet H, Pollitt AY, Begonja AJ, Weber SE, Duerschmied D, Wagner DD, Watson SP, Hartwig JH. A novel interaction between FlnA and Syk regulates platelet ITAM-mediated receptor signaling and function. ACTA ACUST UNITED AC 2010; 207:1967-79. [PMID: 20713593 PMCID: PMC2931168 DOI: 10.1084/jem.20100222] [Citation(s) in RCA: 96] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
Filamin A (FlnA) cross-links actin filaments and connects the Von Willebrand factor receptor GPIb-IX-V to the underlying cytoskeleton in platelets. Because FlnA deficiency is embryonic lethal, mice lacking FlnA in platelets were generated by breeding FlnAloxP/loxP females with GATA1-Cre males. FlnAloxP/y GATA1-Cre males have a macrothrombocytopenia and increased tail bleeding times. FlnA-null platelets have decreased expression and altered surface distribution of GPIbα because they lack the normal cytoskeletal linkage of GPIbα to underlying actin filaments. This results in ∼70% less platelet coverage on collagen-coated surfaces at shear rates of 1,500/s, compared with wild-type platelets. Unexpectedly, however, immunoreceptor tyrosine-based activation motif (ITAM)- and ITAM-like–mediated signals are severely compromised in FlnA-null platelets. FlnA-null platelets fail to spread and have decreased α-granule secretion, integrin αIIbβ3 activation, and protein tyrosine phosphorylation, particularly that of the protein tyrosine kinase Syk and phospholipase C–γ2, in response to stimulation through the collagen receptor GPVI and the C-type lectin-like receptor 2. This signaling defect was traced to the loss of a novel FlnA–Syk interaction, as Syk binds to FlnA at immunoglobulin-like repeat 5. Our findings reveal that the interaction between FlnA and Syk regulates ITAM- and ITAM-like–containing receptor signaling and platelet function.
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Affiliation(s)
- Hervé Falet
- Division of Translational Medicine, Brigham and Women's Hospital, Harvard Medical School, Boston, MA 02115, USA.
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13
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Yuan Y, Zhang W, Yan R, Liao Y, Zhao L, Ruan C, Du X, Dai K. Identification of a novel 14-3-3zeta binding site within the cytoplasmic domain of platelet glycoprotein Ibalpha that plays a key role in regulating the von Willebrand factor binding function of glycoprotein Ib-IX. Circ Res 2009; 105:1177-85. [PMID: 19875727 DOI: 10.1161/circresaha.109.204669] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
RATIONALE The interaction between platelet glycoprotein (GP) Ib-IX and von Willebrand factor (VWF) is initiated by conformational changes in immobilized VWF and is also regulated by the intraplatelet proteins 14-3-3zeta and filamin A. Both 14-3-3zeta and filamin A associate with the cytoplasmic domain of GPIbalpha, whereas little is known about their relationship in regulating the VWF binding function of GPIb-IX. OBJECTIVE To explore the mechanism underlying the roles of 14-3-3zeta and filamin A in regulating the VWF binding function of GPIb-IX. METHODS AND RESULTS A truncation mutant of GPIbalpha (Delta565) deleting the C-terminal 14-3-3zeta binding sites retained 14-3-3zeta binding function, in contrast, deletion of the C-terminal residues 551 to 610 of GPIbalpha totally abolished 14-3-3zeta binding, indicating that the residues 551 to 564 of GPIbalpha are important in the interaction between 14-3-3zeta and GPIb-IX. An antibody recognizing phosphorylated R557GpSLP561 sequence reacted with GPIbalpha suggesting phosphorylation of a population of GPIbalpha molecules at Ser559, and a membrane permeable phosphopeptide (MP-P), R557GpSLP561 corresponding to residues 557 to 561 of GPIbalpha eliminated the association of 14-3-3zeta with Delta565. MP-P also promoted GPIb-IX association with the membrane skeleton, and inhibited ristocetin-induced platelet agglutination, VWF binding to platelets and platelet adhesion to immobilized VWF. Furthermore, a GPIb-IX mutant replacing Ser559 of GPIbalpha with alanine showed an enhanced association with the membrane skeleton, reduced ristocetin-induced VWF binding, and diminished ability to mediate cell adhesion to VWF under flow conditions. CONCLUSIONS These data suggest a phosphorylation-dependent binding of 14-3-3zeta to central filamin A binding site of GPIbalpha, and the dimeric 14-3-3zeta binding to both the C-terminal site and central RGpSLP site inhibits GPIb-IX association with the membrane skeleton and promotes the VWF binding function of GPIb-IX.
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Affiliation(s)
- Yanhong Yuan
- School of Biological Science and Medical Engineering, Beijing University of Aeronautics and Astronautics, 37 Xueyuan Road, Haidian district, Beijing, China
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Unraveling a novel Rac1-mediated signaling pathway that regulates cofilin dephosphorylation and secretion in thrombin-stimulated platelets. Blood 2009; 114:415-24. [DOI: 10.1182/blood-2008-10-183582] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023] Open
Abstract
Abstract
In platelets stimulated by thrombin to secrete and aggregate, cofilin is rapidly dephosphorylated leading to its activation. Cofilin by severing existing actin filaments and stimulating F-actin polymerization on newly created barbed ends dynamizes the actin cytoskeleton. We previously found that cofilin dephosphorylation is Ca2+-dependent and occurs upstream of degranulation in stimulated platelets. We report now in thrombin-stimulated platelets that Rac1 and class II PAKs (PAK4/5/6) were rapidly (within 5 seconds) activated, whereas PAK1/2 (class I PAKs) phosphorylation was slower. The Rac1-specific inhibitor NSC23766 blocked phosphorylation of class II PAKs, but not PAK1/2. Moreover, inhibition of the Ca2+/calmodulin-dependent phosphatase calcineurin inhibited Rac1 activation and class II PAKs phosphorylation. Prevention of Rac1 activation by calcineurin inhibition or NSC23766 also blocked cofilin dephosphorylation and platelet granule secretion indicating that a calcineurin/Rac1/class II PAKs pathway regulates cofilin dephosphorylation leading to secretion. We further found that PI3-kinases were activated downstream of Rac1, but were not involved in regulating cofilin dephosphorylation and secretion in thrombin-stimulated platelets. Our study unravels a Ca2+-dependent pathway of secretion in stimulated platelets as a signaling pathway linking Rac1 activation to actin dynamics: calcineurin→Rac1→class II PAKs→cofilin activation. We further demonstrate that this pathway is separate and independent of the protein kinase C (PKC) pathway mediating secretion.
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Ithychanda SS, Das M, Ma YQ, Ding K, Wang X, Gupta S, Wu C, Plow EF, Qin J. Migfilin, a molecular switch in regulation of integrin activation. J Biol Chem 2009; 284:4713-22. [PMID: 19074766 PMCID: PMC2640964 DOI: 10.1074/jbc.m807719200] [Citation(s) in RCA: 94] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2008] [Revised: 12/01/2008] [Indexed: 01/08/2023] Open
Abstract
The linkage of heterodimeric (alpha/beta) integrin receptors with their extracellular matrix ligands and intracellular actin cytoskeleton is a fundamental step for controlling cell adhesion and migration. Binding of the actin-linking protein, talin, to integrin beta cytoplasmic tails (CTs) induces high affinity ligand binding (integrin activation), whereas binding of another actin-linking protein, filamin, to the integrin beta CTs negatively regulates this process by blocking the talin-integrin interaction. Here we show structurally that migfilin, a novel cytoskeletal adaptor highly enriched in the integrin adhesion sites, strongly interacts with the same region in filamin where integrin beta CTs bind. We further demonstrate that the migfilin interaction dissociates filamin from integrin and promotes the talin/integrin binding and integrin activation. Migfilin thus acts as a molecular switch to disconnect filamin from integrin for regulating integrin activation and dynamics of extracellular matrix-actin linkage.
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Affiliation(s)
- Sujay Subbayya Ithychanda
- Department of Molecular Cardiology, Lerner Research Institute, Cleveland Clinic, Cleveland, Ohio 44195, USA
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Abstract
PURPOSE OF REVIEW The platelet adhesion receptor, the glycoprotein Ib-IX-V complex, not only mediates platelet adhesion but also transmits signals leading to platelet activation, aggregation and secretion. Significant progress has been made recently on the signaling pathways and regulatory mechanisms involving glycoprotein Ib-IX-V function. RECENT FINDINGS The interaction of glycoprotein Ib-IX-V with its ligand, von Willebrand factor, is dually controlled by von Willebrand factor conformation and intracellular signal-mediated regulation of glycoprotein Ib-IX-V receptor function that requires the zeta isoform of the 14-3-3 protein family (14-3-3zeta). Glycoprotein Ib-IX-V signaling is mediated by the Src family of protein kinases, phospholipase C, calcium elevation, phosphoinositol 3-kinase, and multiple amplification mechanisms including the nitric oxide-cGMP pathway, the mitogen-activated protein kinase pathway, the immunoreceptor tyrosine-based activation motif pathway, and ADP and thromboxane A2 pathways. SUMMARY Progress in understanding the mechanism(s) regulating glycoprotein Ib-IX-V should help develop inhibitors and modifiers that interfere or augment its von Willebrand factor binding function and thus be useful for treating thrombosis and bleeding disorders. Characterization of intracellular molecules and pathways in glycoprotein Ib-IX-V signaling has implications in the development of new agents and for the use of existing drugs that affect glycoprotein Ib-IX-V signaling.
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Affiliation(s)
- Xiaoping Du
- Department of Pharmacology, University of Illinois College of Medicine, Chicago, IL 60612, USA.
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CORRIGENDUM. J Thromb Haemost 2006. [DOI: 10.1111/j.1538-7836.2006.02334.x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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