1
|
Liu K, Hao Z, Zheng H, Wang H, Zhang L, Yan M, Tuerhong R, Zhou Y, Wang Y, Pang T, Shi L. Repurposing of rilpivirine for preventing platelet β3 integrin-dependent thrombosis by targeting c-Src active autophosphorylation. Thromb Res 2023; 229:53-68. [PMID: 37413892 DOI: 10.1016/j.thromres.2023.06.031] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2023] [Revised: 06/19/2023] [Accepted: 06/30/2023] [Indexed: 07/08/2023]
Abstract
BACKGROUND HIV-infected individuals are known to be at higher risk for thrombotic cardiovascular disease (CVD), which may also be differentially affected by components of anti-HIV drugs. To identify the effects of a series of FDA-approved anti-HIV drugs on platelet aggregation in humans, focusing on the novel pharmacological effects of rilpivirine (RPV), a reverse transcriptase inhibitor, on platelet function both in vitro and in vivo and the mechanisms involved. METHODS AND RESULTS In vitro studies showed that RPV was the only anti-HIV reagent that consistently and efficiently inhibited aggregation elicited by different agonists, exocytosis, morphological extension on fibrinogen, and clot retraction. Treatment of mice with RPV significantly prevented thrombus formation in FeCl3-injured mesenteric vessels, postcava with stenosis surgery, and ADP -induced pulmonary embolism models without defects in platelet viability, tail bleeding, and coagulation activities. RPV also improved cardiac performance in mice with post-ischemic reperfusion. A mechanistic study revealed that RPV preferentially attenuated fibrinogen-stimulated Tyr773 phosphorylation of β3-integrin by inhibiting Tyr419 autophosphorylation of c-Src. Molecular docking and surface plasmon resonance analyses showed that RPV can bind directly to c-Src. Further mutational analysis showed that the Phe427 residue of c-Src is critical for RPV interaction, suggesting a novel interaction site for targeting c-Src to block β3-integrin outside-in signaling. CONCLUSION These results demonstrated that RPV was able to prevent the progression of thrombotic CVDs by interrupting β3-integrin-mediated outside-in signaling via inhibiting c-Src activation without hemorrhagic side effects, highlighting RPV as a promising reagent for the prevention and therapy of thrombotic CVDs.
Collapse
Affiliation(s)
- Kui Liu
- Xiamen Key Laboratory of Cardiovascular Disease, Xiamen Cardiovascular Hospital of Xiamen University, School of Medicine, Xiamen University, 2999 Jinshan Road, Xiamen 361000, China; State Key Laboratory of Natural Medicines, New Drug Screening Center, Key Laboratory of Drug Quality Control and Pharmacovigilance (Ministry of Education), China Pharmaceutical University, Nanjing 210009, China
| | - Zhen Hao
- Xiamen Key Laboratory of Cardiovascular Disease, Xiamen Cardiovascular Hospital of Xiamen University, School of Medicine, Xiamen University, 2999 Jinshan Road, Xiamen 361000, China; College of Basic Medical Sciences, Dalian Medical University, No. 9 West Section, South Lv shun Road, Dalian 116044, China
| | - Hao Zheng
- College of Basic Medical Sciences, Dalian Medical University, No. 9 West Section, South Lv shun Road, Dalian 116044, China
| | - Haojie Wang
- Department of Medicinal Chemistry, School of Pharmacy, Fudan University, Shanghai 201203, China
| | - Luying Zhang
- College of Basic Medical Sciences, Dalian Medical University, No. 9 West Section, South Lv shun Road, Dalian 116044, China
| | - Minghui Yan
- College of Basic Medical Sciences, Dalian Medical University, No. 9 West Section, South Lv shun Road, Dalian 116044, China
| | - Reyisha Tuerhong
- College of Basic Medical Sciences, Dalian Medical University, No. 9 West Section, South Lv shun Road, Dalian 116044, China
| | - Yuling Zhou
- Xiamen Key Laboratory of Cardiovascular Disease, Xiamen Cardiovascular Hospital of Xiamen University, School of Medicine, Xiamen University, 2999 Jinshan Road, Xiamen 361000, China
| | - Yan Wang
- Xiamen Key Laboratory of Cardiovascular Disease, Xiamen Cardiovascular Hospital of Xiamen University, School of Medicine, Xiamen University, 2999 Jinshan Road, Xiamen 361000, China.
| | - Tao Pang
- State Key Laboratory of Natural Medicines, New Drug Screening Center, Key Laboratory of Drug Quality Control and Pharmacovigilance (Ministry of Education), China Pharmaceutical University, Nanjing 210009, China.
| | - Lei Shi
- Xiamen Key Laboratory of Cardiovascular Disease, Xiamen Cardiovascular Hospital of Xiamen University, School of Medicine, Xiamen University, 2999 Jinshan Road, Xiamen 361000, China; College of Basic Medical Sciences, Dalian Medical University, No. 9 West Section, South Lv shun Road, Dalian 116044, China.
| |
Collapse
|
2
|
Sun S, Qiao B, Han Y, Wang B, Wei S, Chen Y. Posttranslational modifications of platelet adhesion receptors. Pharmacol Res 2022; 183:106413. [PMID: 36007773 DOI: 10.1016/j.phrs.2022.106413] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/01/2022] [Revised: 08/11/2022] [Accepted: 08/19/2022] [Indexed: 10/15/2022]
Abstract
Platelets play a key role in normal hemostasis, whereas pathological platelet adhesion is involved in various cardiovascular events. The underlying cause in cardiovascular events involves plaque rupture leading to subsequent platelet adhesion, activation, release, and eventual thrombosis. Traditional antithrombotic drugs often target the signal transduction process of platelet adhesion receptors by influencing the synthesis of some key molecules, and their effects are limited. Posttranslational modifications (PTMs) of platelet adhesion receptors increase the functional diversity of the receptors and affect platelet physiological and pathological processes. Antithrombotic drugs targeting PTMs of platelet adhesion receptors may represent a new therapeutic idea. In this review, various PTMs, including phosphorylation, glycosylation, ubiquitination, nitrosylation, methylation, lipidation, and proteolysis, of three platelet adhesion receptors, glycoprotein Ib-IX-V (GPIb-IX-V), glycoprotein VI (GPVI), and integrin αIIbβ3, are reviewed. It is important to comprehensively understand the PTMs process of platelet adhesion receptors.
Collapse
Affiliation(s)
- Shukun Sun
- Department of Emergency and Chest Pain Center, Qilu Hospital of Shandong University, Jinan, Shandong 250012, China; Clinical Research Center for Emergency and Critical Care Medicine of Shandong Province, Institute of Emergency and Critical Care Medicine of Shandong University, Qilu Hospital of Shandong University, Jinan, Shandong 250012, China; Key Laboratory of Emergency and Critical Care Medicine of Shandong Province, Key Laboratory of Cardiopulmonary-Cerebral Resuscitation Research of Shandong Province, Qilu Hospital of Shandong University, Jinan, Shandong 250012, China; The Key Laboratory of Cardiovascular Remodeling and Function Research, Chinese Ministry of Education, Chinese Ministry of Health and Chinese Academy of Medical Sciences, Qilu Hospital of Shandong University, Jinan, Shandong 250012, China; The State and Shandong Province Joint Key Laboratory of Translational Cardiovascular Medicine, Qilu Hospital of Shandong University, Jinan, Shandong 250012, China
| | - Bao Qiao
- Department of Emergency and Chest Pain Center, Qilu Hospital of Shandong University, Jinan, Shandong 250012, China; Clinical Research Center for Emergency and Critical Care Medicine of Shandong Province, Institute of Emergency and Critical Care Medicine of Shandong University, Qilu Hospital of Shandong University, Jinan, Shandong 250012, China; Key Laboratory of Emergency and Critical Care Medicine of Shandong Province, Key Laboratory of Cardiopulmonary-Cerebral Resuscitation Research of Shandong Province, Qilu Hospital of Shandong University, Jinan, Shandong 250012, China; The Key Laboratory of Cardiovascular Remodeling and Function Research, Chinese Ministry of Education, Chinese Ministry of Health and Chinese Academy of Medical Sciences, Qilu Hospital of Shandong University, Jinan, Shandong 250012, China; The State and Shandong Province Joint Key Laboratory of Translational Cardiovascular Medicine, Qilu Hospital of Shandong University, Jinan, Shandong 250012, China
| | - Yu Han
- Department of Emergency and Chest Pain Center, Qilu Hospital of Shandong University, Jinan, Shandong 250012, China; Clinical Research Center for Emergency and Critical Care Medicine of Shandong Province, Institute of Emergency and Critical Care Medicine of Shandong University, Qilu Hospital of Shandong University, Jinan, Shandong 250012, China; Key Laboratory of Emergency and Critical Care Medicine of Shandong Province, Key Laboratory of Cardiopulmonary-Cerebral Resuscitation Research of Shandong Province, Qilu Hospital of Shandong University, Jinan, Shandong 250012, China; The Key Laboratory of Cardiovascular Remodeling and Function Research, Chinese Ministry of Education, Chinese Ministry of Health and Chinese Academy of Medical Sciences, Qilu Hospital of Shandong University, Jinan, Shandong 250012, China; The State and Shandong Province Joint Key Laboratory of Translational Cardiovascular Medicine, Qilu Hospital of Shandong University, Jinan, Shandong 250012, China
| | - Bailu Wang
- Clinical Trial Center, Qilu Hospital of Shandong University, Jinan, Shandong 250012, China
| | - Shujian Wei
- Department of Emergency and Chest Pain Center, Qilu Hospital of Shandong University, Jinan, Shandong 250012, China; Clinical Research Center for Emergency and Critical Care Medicine of Shandong Province, Institute of Emergency and Critical Care Medicine of Shandong University, Qilu Hospital of Shandong University, Jinan, Shandong 250012, China; Key Laboratory of Emergency and Critical Care Medicine of Shandong Province, Key Laboratory of Cardiopulmonary-Cerebral Resuscitation Research of Shandong Province, Qilu Hospital of Shandong University, Jinan, Shandong 250012, China; The Key Laboratory of Cardiovascular Remodeling and Function Research, Chinese Ministry of Education, Chinese Ministry of Health and Chinese Academy of Medical Sciences, Qilu Hospital of Shandong University, Jinan, Shandong 250012, China; The State and Shandong Province Joint Key Laboratory of Translational Cardiovascular Medicine, Qilu Hospital of Shandong University, Jinan, Shandong 250012, China.
| | - Yuguo Chen
- Department of Emergency and Chest Pain Center, Qilu Hospital of Shandong University, Jinan, Shandong 250012, China; Clinical Research Center for Emergency and Critical Care Medicine of Shandong Province, Institute of Emergency and Critical Care Medicine of Shandong University, Qilu Hospital of Shandong University, Jinan, Shandong 250012, China; Key Laboratory of Emergency and Critical Care Medicine of Shandong Province, Key Laboratory of Cardiopulmonary-Cerebral Resuscitation Research of Shandong Province, Qilu Hospital of Shandong University, Jinan, Shandong 250012, China; The Key Laboratory of Cardiovascular Remodeling and Function Research, Chinese Ministry of Education, Chinese Ministry of Health and Chinese Academy of Medical Sciences, Qilu Hospital of Shandong University, Jinan, Shandong 250012, China; The State and Shandong Province Joint Key Laboratory of Translational Cardiovascular Medicine, Qilu Hospital of Shandong University, Jinan, Shandong 250012, China.
| |
Collapse
|
3
|
Phosphorylation of Kindlins and the Control of Integrin Function. Cells 2021; 10:cells10040825. [PMID: 33916922 PMCID: PMC8067640 DOI: 10.3390/cells10040825] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2021] [Revised: 03/31/2021] [Accepted: 04/02/2021] [Indexed: 12/17/2022] Open
Abstract
Integrins serve as conduits for the transmission of information between cells and their extracellular environment. Signaling across integrins is bidirectional, transducing both inside-out and outside-signaling. Integrin activation, a transition from a low affinity/avidity state to a high affinity/avidity state for cognate ligands, is an outcome of inside-signaling. Such activation is particularly important for the recognition of soluble ligands by blood cells but also influences cell-cell and cell-matrix interactions. Integrin activation depends on a complex series of interactions, which both accelerate and inhibit their interconversion from the low to the high affinity/avidity state. There are three components regarded as being most proximately involved in integrin activation: the integrin cytoplasmic tails, talins and kindlins. The participation of each of these molecules in integrin activation is highly regulated by post-translation modifications. The importance of targeted phosphorylation of integrin cytoplasmic tails and talins in integrin activation is well-established, but much less is known about the role of post-translational modification of kindlins. The kindlins, a three-member family of 4.1-ezrin-radixin-moesin (FERM)-domain proteins in mammals, bind directly to the cytoplasmic tails of integrin beta subunits. This commentary provides a synopsis of the emerging evidence for the role of kindlin phosphorylation in integrin regulation.
Collapse
|
4
|
Structure-guided design of pure orthosteric inhibitors of αIIbβ3 that prevent thrombosis but preserve hemostasis. Nat Commun 2020; 11:398. [PMID: 31964886 PMCID: PMC6972956 DOI: 10.1038/s41467-019-13928-2] [Citation(s) in RCA: 25] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2019] [Accepted: 12/06/2019] [Indexed: 02/07/2023] Open
Abstract
A prevailing dogma is that inhibition of vascular thrombosis by antagonizing platelet integrin αIIbβ3 cannot be achieved without compromising hemostasis, thus causing serious bleeding and increased morbidity and mortality. It is speculated that these adverse outcomes result from drug-induced activating conformational changes in αIIbβ3 but direct proof is lacking. Here, we report the structure-guided design of peptide Hr10 and a modified form of the partial agonist drug tirofiban that act as "pure" antagonists of αIIbβ3, i.e., they no longer induce the conformational changes in αIIbβ3. Both agents inhibit human platelet aggregation but preserve clot retraction. Hr10 and modified tirofiban are as effective as partial agonist drugs in inhibiting vascular thrombosis in humanized mice, but neither causes serious bleeding, establishing a causal link between partial agonism and impaired hemostasis. Pure orthosteric inhibitors of αIIbβ3 may thus provide safer alternatives for human therapy, and valuable tools to probe structure-activity relationships in integrins.
Collapse
|
5
|
Regulation of cell adhesion: a collaborative effort of integrins, their ligands, cytoplasmic actors, and phosphorylation. Q Rev Biophys 2019; 52:e10. [PMID: 31709962 DOI: 10.1017/s0033583519000088] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Integrins are large heterodimeric type 1 membrane proteins expressed in all nucleated mammalian cells. Eighteen α-chains and eight β-chains can combine to form 24 different integrins. They are cell adhesion proteins, which bind to a large variety of cellular and extracellular ligands. Integrins are required for cell migration, hemostasis, translocation of cells out from the blood stream and further movement into tissues, but also for the immune response and tissue morphogenesis. Importantly, integrins are not usually active as such, but need activation to become adhesive. Integrins are activated by outside-in activation through integrin ligand binding, or by inside-out activation through intracellular signaling. An important question is how integrin activity is regulated, and this topic has recently drawn much attention. Changes in integrin affinity for ligand binding are due to allosteric structural alterations, but equally important are avidity changes due to integrin clustering in the plane of the plasma membrane. Recent studies have partially solved how integrin cell surface structures change during activation. The integrin cytoplasmic domains are relatively short, but by interacting with a variety of cytoplasmic proteins in a regulated manner, the integrins acquire a number of properties important not only for cell adhesion and movement, but also for cellular signaling. Recent work has shown that specific integrin phosphorylations play pivotal roles in the regulation of integrin activity. Our purpose in this review is to integrate the present knowledge to enable an understanding of how cell adhesion is dynamically regulated.
Collapse
|
6
|
Cao Z, Suo X, Chu Y, Xu Z, Bao Y, Miao C, Deng W, Mao K, Gao J, Xu Z, Ma YQ. Peptides derived from the integrin β cytoplasmic tails inhibit angiogenesis. Cell Commun Signal 2018; 16:38. [PMID: 29970081 PMCID: PMC6029062 DOI: 10.1186/s12964-018-0248-8] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2018] [Accepted: 06/19/2018] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Integrins are essential regulators of angiogenesis. However, the antiangiogenic potential of peptides derived from the integrin cytoplasmic tails (CT) remains mostly undetermined. METHODS Here we designed a panel of membrane-penetrating peptides (termed as mβCTPs), each comprising a C-terminal NxxY motif from one of the conserved integrin β CTs, and evaluated their antiangiogenic ability using both in vitro and in vivo approaches. RESULTS We found that mβ3CTP, mβ5CTP and mβ6CTP, derived respectively from the integrin β3, β5 and β6 CTs, but not others, exhibit antiangiogenic ability. Interestingly, we observed that the integrin β3, β5 and β6 CTs but not others are able to interact with β3-endonexin. In addition, the antiangiogenic core in mβ3CTP is identical to a previously identified β3-endonexin binding region in the integrin β3 CT, indicating that the antiangiogenic mβCTPs may function via their binding to β3-endonexin. Consistently, knockdown of endogenous β3-endonexin in HUVECs significantly suppresses tube formation, suggesting that β3-endonexin is proangiogenic. However, neither treatment with the antiangiogenic mβCTPs nor knockdown of endogenous β3-endonexin affects integrin-mediated HUVEC adhesion and migration, indicating that their antiangiogenic effect may not rely on directly regulating integrin activity. Importantly, both treatment with the antiangiogenic mβCTPs and knockdown of endogenous β3-endonexin in HUVECs inhibit VEGF expression and cell proliferation, thereby providing mechanistic explanations for the functional consequences. CONCLUSION Our results suggest that the antiangiogenic mβCTPs can interact with β3-endonexin in vascular endothelial cells and suppress its function in regulating VEGF expression and cell proliferation, thus disclosing a unique pathway that may be useful for developing novel antiangiogenic strategies.
Collapse
Affiliation(s)
- Zhongyuan Cao
- School of Environmental and Chemical Engineering, Shanghai University, Shanghai, China.,School of Life Sciences, Shanghai University, Shanghai, China
| | - Xinfeng Suo
- School of Life Sciences, Shanghai University, Shanghai, China
| | - Yudan Chu
- School of Life Sciences, Shanghai University, Shanghai, China
| | - Zhou Xu
- School of Life Sciences, Shanghai University, Shanghai, China
| | - Yun Bao
- School of Life Sciences, Shanghai University, Shanghai, China
| | - Chunxiao Miao
- School of Life Sciences, Shanghai University, Shanghai, China
| | - Wenfeng Deng
- School of Life Sciences, Shanghai University, Shanghai, China
| | - Kaijun Mao
- School of Life Sciences, Shanghai University, Shanghai, China
| | - Juan Gao
- School of Life Sciences, Shanghai University, Shanghai, China
| | - Zhen Xu
- School of Life Sciences, Shanghai University, Shanghai, China. .,Blood Research Institute, Blood Center of Wisconsin, part of Versiti, 8727 Watertown Plank Rd, Milwaukee, WI, 53226, USA.
| | - Yan-Qing Ma
- School of Environmental and Chemical Engineering, Shanghai University, Shanghai, China. .,School of Life Sciences, Shanghai University, Shanghai, China. .,Blood Research Institute, Blood Center of Wisconsin, part of Versiti, 8727 Watertown Plank Rd, Milwaukee, WI, 53226, USA.
| |
Collapse
|
7
|
Feng W, Valiyaveettil M, Dudiki T, Mahabeleshwar GH, Andre P, Podrez EA, Byzova TV. β 3 phosphorylation of platelet α IIbβ 3 is crucial for stability of arterial thrombus and microparticle formation in vivo. Thromb J 2017; 15:22. [PMID: 28860945 PMCID: PMC5576334 DOI: 10.1186/s12959-017-0145-1] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2017] [Accepted: 07/08/2017] [Indexed: 01/08/2023] Open
Abstract
Background It is well accepted that functional activity of platelet integrin αIIbβ3 is crucial for hemostasis and thrombosis. The β3 subunit of the complex undergoes tyrosine phosphorylation shown to be critical for outside-in integrin signaling and platelet clot retraction ex vivo. However, the role of this important signaling event in other aspects of prothrombotic platelet function is unknown. Method Here, we assess the role of β3 tyrosine phosphorylation in platelet function regulation with a knock-in mouse strain, where two β3 cytoplasmic tyrosines are mutated to phenylalanine (DiYF). We employed platelet transfusion technique and intravital microscopy for observing the cellular events involved in specific steps of thrombus growth to investigate in detail the role of β3 tyrosine phosphorylation in arterial thrombosis in vivo. Results Upon injury, DiYF mice exhibited delayed arterial occlusion and unstable thrombus formation. The mean thrombus volume in DiYF mice formed on collagen was only 50% of that in WT. This effect was attributed to DiYF platelets but not to other blood cells and endothelium, which also carry these mutations. Transfusion of isolated DiYF but not WT platelets into irradiated WT mice resulted in reversal of the thrombotic phenotype and significantly prolonged blood vessel occlusion times. DiYF platelets exhibited reduced adhesion to collagen under in vitro shear conditions compared to WT platelets. Decreased platelet microparticle release after activation, both in vitro and in vivo, were observed in DiYF mice compared to WT mice. Conclusion β3 tyrosine phosphorylation of platelet αIIbβ3 regulates both platelet pro-thrombotic activity and the formation of a stable platelet thrombus, as well as arterial microparticle release.
Collapse
Affiliation(s)
- Weiyi Feng
- Department of Molecular Cardiology, The Cleveland Clinic Foundation, Cleveland, 44195 OH USA.,The First Affiliated Hospital, School of Medicine, Xi'an Jiaotong University, Xi'an, Shaanxi 710061 China
| | - Manojkumar Valiyaveettil
- Department of Molecular Cardiology, The Cleveland Clinic Foundation, Cleveland, 44195 OH USA.,US Army Medical Materiel Development Activity, 1430 Veterans Drive, Fort Detrick, Frederick, MD 21702 USA
| | - Tejasvi Dudiki
- Department of Molecular Cardiology, The Cleveland Clinic Foundation, Cleveland, 44195 OH USA
| | | | | | - Eugene A Podrez
- Department of Molecular Cardiology, The Cleveland Clinic Foundation, Cleveland, 44195 OH USA
| | - Tatiana V Byzova
- Department of Molecular Cardiology, The Cleveland Clinic Foundation, Cleveland, 44195 OH USA
| |
Collapse
|
8
|
Abstract
Integrin αIIbβ3 is a highly abundant heterodimeric platelet receptor that can transmit information bidirectionally across the plasma membrane, and plays a critical role in hemostasis and thrombosis. Upon platelet activation, inside-out signaling pathways increase the affinity of αIIbβ3 for fibrinogen and other ligands. Ligand binding and integrin clustering subsequently stimulate outside-in signaling, which initiates and amplifies a range of cellular events driving essential platelet processes such as spreading, thrombus consolidation, and clot retraction. Integrin αIIbβ3 has served as an excellent model for the study of integrin biology, and it has become clear that integrin outside-in signaling is highly complex and involves a vast array of enzymes, signaling adaptors, and cytoskeletal components. In this review, we provide a concise but comprehensive overview of αIIbβ3 outside-in signaling, focusing on the key players involved, and how they cooperate to orchestrate this critical aspect of platelet biology. We also discuss gaps in the current understanding of αIIbβ3 outside-in signaling and highlight avenues for future investigation.
Collapse
|
9
|
Unsworth AJ, Kriek N, Bye AP, Naran K, Sage T, Flora GD, Gibbins JM. PPARγ agonists negatively regulate αIIbβ3 integrin outside-in signaling and platelet function through up-regulation of protein kinase A activity. J Thromb Haemost 2017; 15:356-369. [PMID: 27896950 PMCID: PMC5396324 DOI: 10.1111/jth.13578] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2016] [Indexed: 12/31/2022]
Abstract
Essentials peroxisome proliferator-activated receptor γ (PPARγ) agonists inhibit platelet function. PPARγ agonists negatively regulate outside-in signaling via integrin αIIbβ3. PPARγ agonists disrupt the interaction of Gα13 with integrin β3. This is attributed to an upregulation of protein kinase A activity. SUMMARY Background Agonists for the peroxisome proliferator-activated receptor (PPARγ) have been shown to have inhibitory effects on platelet activity following stimulation by GPVI and GPCR agonists. Objectives Profound effects on thrombus formation led us to suspect a role for PPARγ agonists in the regulation of integrin αIIbβ3 mediated signaling. Both GPVI and GPCR signaling pathways lead to αIIbβ3 activation, and signaling through αIIbβ3 plays a critical role in platelet function and normal hemostasis. Methods The effects of PPARγ agonists on the regulation of αIIbβ3 outside-in signaling was determined by monitoring the ability of platelets to adhere and spread on fibrinogen and undergo clot retraction. Effects on signaling components downstream of αIIbβ3 activation were also determined following adhesion to fibrinogen by Western blotting. Results Treatment of platelets with PPARγ agonists inhibited platelet adhesion and spreading on fibrinogen and diminished clot retraction. A reduction in phosphorylation of several components of αIIbβ3 signaling, including the integrin β3 subunit, Syk, PLCγ2, focal adhesion kinase (FAK) and Akt, was also observed as a result of reduced interaction of the integrin β3 subunit with Gα13. Studies of VASP phosphorylation revealed that this was because of an increase in PKA activity following treatment with PPARγ receptor agonists. Conclusions This study provides further evidence for antiplatelet actions of PPARγ agonists, identifies a negative regulatory role for PPARγ agonists in the control of integrin αIIbβ3 outside-in signaling, and provides a molecular basis by which the PPARγ agonists negatively regulate platelet activation and thrombus formation.
Collapse
Affiliation(s)
- A. J. Unsworth
- Institute for Cardiovascular and Metabolic ResearchSchool of Biological SciencesUniversity of ReadingReadingUK
| | - N. Kriek
- Institute for Cardiovascular and Metabolic ResearchSchool of Biological SciencesUniversity of ReadingReadingUK
| | - A. P. Bye
- Institute for Cardiovascular and Metabolic ResearchSchool of Biological SciencesUniversity of ReadingReadingUK
| | - K. Naran
- Institute for Cardiovascular and Metabolic ResearchSchool of Biological SciencesUniversity of ReadingReadingUK
| | - T. Sage
- Institute for Cardiovascular and Metabolic ResearchSchool of Biological SciencesUniversity of ReadingReadingUK
| | - G. D. Flora
- Institute for Cardiovascular and Metabolic ResearchSchool of Biological SciencesUniversity of ReadingReadingUK
| | - J. M. Gibbins
- Institute for Cardiovascular and Metabolic ResearchSchool of Biological SciencesUniversity of ReadingReadingUK
| |
Collapse
|
10
|
Platelets and physics: How platelets “feel” and respond to their mechanical microenvironment. Blood Rev 2015; 29:377-86. [DOI: 10.1016/j.blre.2015.05.002] [Citation(s) in RCA: 45] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2015] [Revised: 05/04/2015] [Accepted: 05/04/2015] [Indexed: 01/08/2023]
|
11
|
Roll, adhere, spread and contract: structural mechanics of platelet function. Eur J Cell Biol 2015; 94:129-38. [PMID: 25655000 DOI: 10.1016/j.ejcb.2015.01.001] [Citation(s) in RCA: 43] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2014] [Revised: 12/26/2014] [Accepted: 01/07/2015] [Indexed: 12/31/2022] Open
Abstract
Platelets are involved in life-sustaining processes such as hemostasis, wound healing, atherothrombosis and angiogenesis. Mechanical trauma to blood vessels causes platelet activation resulting in their adherence and clot formation at the damaged site, culminating in clot retraction and tissue repair. Two of the major players underlying this process are the cytoskeleton, i.e., actin and microtubules, and the membrane integrin receptors. Rare congenital bleeding disorders such as Glanzmann thrombasthenia and Bernard-Soulier syndrome are associated with genetic alterations of platelet surface receptors, also affecting the platelet cytoskeletal structure. In this review, we summarize the current knowledge about platelet structure and adhesion, and delve into the mechanical aspects of platelet function. Platelets lack a nucleus, and can thus provide a minimal model of a biological cell. New biophysical tools may help to scrutinize platelets anew and to extend the existing knowledge on cell biology.
Collapse
|
12
|
Lin X, Vinogradova O. Phospho-Tyrosine(s) vs. Phosphatidylinositol Binding in Shc Mediated Integrin Signaling. ACTA ACUST UNITED AC 2015; 5:17-31. [PMID: 25893141 PMCID: PMC4397963 DOI: 10.4236/ajmb.2015.52003] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
The Shc adaptor protein, particularly its p52 isoform, has been identified as a primary signaling partner for the tyrosine(s)-phosphorylated cytoplasmic tails of activated β3 integrins. Inspired by our recent structure of the Shc PTB domain in complex with a bi-phosphorylated peptide derived from β3 cytoplasmic tail, we have initiated the investigation of Shc interaction with phospholipids of the membrane. We are particularly focused on PtdIns and their effects on Shc mediated integrin signaling in vitro. Here we present thermodynamic profiles and molecular details of the interactions between Shc, integrin, and PtdIns, all of which have been studied by ITC and solution NMR methods. A model of p52 Shc interaction with phosphorylated β3 integrin cytoplasmic tail at the cytosolic face of the plasma membrane is proposed based on these data.
Collapse
Affiliation(s)
- Xiaochen Lin
- Department of Pharmaceutical Sciences, School of Pharmacy, University of Connecticut at Storrs, Storrs, USA
| | - Olga Vinogradova
- Department of Pharmaceutical Sciences, School of Pharmacy, University of Connecticut at Storrs, Storrs, USA
| |
Collapse
|
13
|
EphB2 regulates contact-dependent and contact-independent signaling to control platelet function. Blood 2014; 125:720-30. [PMID: 25370417 DOI: 10.1182/blood-2014-06-585083] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
The Eph kinases, EphA4 and EphB1, and their ligand, ephrinB1, have been previously reported to be present in platelets where they contribute to thrombus stability. Although thrombus formation allows for Eph-ephrin engagement and bidirectional signaling, the importance specifically of Eph kinase or ephrin signaling in regulating platelet function remained unidentified. In the present study, a genetic approach was used in mice to establish the contribution of signaling orchestrated by the cytoplasmic domain of EphB2 (a newly discovered Eph kinase in platelets) in platelet activation and thrombus formation. We conclude that EphB2 signaling is involved in the regulation of thrombus formation and clot retraction. Furthermore, the cytoplasmic tail of this Eph kinase regulates initial platelet activation in a contact-independent manner in the absence of Eph-ephrin ligation between platelets. Together, these data demonstrate that EphB2 signaling not only modulates platelet function within a thrombus but is also involved in the regulation of the function of isolated platelets in a contact-independent manner.
Collapse
|
14
|
Clot retraction is mediated by factor XIII-dependent fibrin-αIIbβ3-myosin axis in platelet sphingomyelin-rich membrane rafts. Blood 2013; 122:3340-8. [PMID: 24002447 DOI: 10.1182/blood-2013-04-491290] [Citation(s) in RCA: 58] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Membrane rafts are spatially and functionally heterogenous in the cell membrane. We observed that lysenin-positive sphingomyelin (SM)-rich rafts are identified histochemically in the central region of adhered platelets where fibrin and myosin are colocalized on activation by thrombin. The clot retraction of SM-depleted platelets from SM synthase knockout mouse was delayed significantly, suggesting that platelet SM-rich rafts are involved in clot retraction. We found that fibrin converted by thrombin translocated immediately in platelet detergent-resistant membrane (DRM) rafts but that from Glanzmann's thrombasthenic platelets failed. The fibrinogen γ-chain C-terminal (residues 144-411) fusion protein translocated to platelet DRM rafts on thrombin activation, but its mutant that was replaced by A398A399 at factor XIII crosslinking sites (Q398Q399) was inhibited. Furthermore, fibrin translocation to DRM rafts was impaired in factor XIII A subunit-deficient mouse platelets, which show impaired clot retraction. In the cytoplasm, myosin translocated concomitantly with fibrin translocation into the DRM raft of thrombin-stimulated platelets. Furthermore, the disruption of SM-rich rafts by methyl-β-cyclodextrin impaired myosin activation and clot retraction. Thus, we propose that clot retraction takes place in SM-rich rafts where a fibrin-αIIbβ3-myosin complex is formed as a primary axis to promote platelet contraction.
Collapse
|
15
|
New insights into adhesion signaling in bone formation. INTERNATIONAL REVIEW OF CELL AND MOLECULAR BIOLOGY 2013; 305:1-68. [PMID: 23890379 DOI: 10.1016/b978-0-12-407695-2.00001-9] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Mineralized tissues that are protective scaffolds in the most primitive species have evolved and acquired more specific functions in modern animals. These are as diverse as support in locomotion, ion homeostasis, and precise hormonal regulation. Bone formation is tightly controlled by a balance between anabolism, in which osteoblasts are the main players, and catabolism mediated by the osteoclasts. The bone matrix is deposited in a cyclic fashion during homeostasis and integrates several environmental cues. These include diffusible elements that would include estrogen or growth factors and physicochemical parameters such as bone matrix composition, stiffness, and mechanical stress. Therefore, the microenvironment is of paramount importance for controlling this delicate equilibrium. Here, we provide an overview of the most recent data highlighting the role of cell-adhesion molecules during bone formation. Due to the very large scope of the topic, we focus mainly on the role of the integrin receptor family during osteogenesis. Bone phenotypes of some deficient mice as well as diseases of human bones involving cell adhesion during this process are discussed in the context of bone physiology.
Collapse
|
16
|
G(12/13) signaling pathways substitute for integrin αIIbβ3-signaling for thromboxane generation in platelets. PLoS One 2011; 6:e16586. [PMID: 21347357 PMCID: PMC3037367 DOI: 10.1371/journal.pone.0016586] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2010] [Accepted: 12/21/2010] [Indexed: 11/19/2022] Open
Abstract
BACKGROUND We have previously shown that ADP-induced TXA(2) generation requires signaling from αIIbβ3 integrin in platelets. Here we observed that, unlike ADP, protease-activated receptor (PAR)-mediated TXA(2) generation occurs independently of αIIbβ3. PAR agonists, but not ADP, activate G(12/13) signaling pathways. Hence, we evaluated the role of these pathways in TXA(2) generation. PRINCIPAL FINDINGS Inhibition of ADP-induced thromboxane generation by fibrinogen receptor antagonist SC57101 was rescued by co-stimulation of G(12/13) pathways with YFLLRNP. This observation suggested an existence of a common signaling effector downstream of integrins and G(12/13) pathways. Hence, we evaluated role of three potential tyrosine kinases; c-Src, Syk and FAK (Focal Adhesion Kinase) that are known to be activated by integrins. c-Src and Syk kinase did not play a role in ADP-induced functional responses in platelets. Selective activation of G(12/13) pathways resulted in the activation of FAK, in the absence of integrin signaling. Interestingly, αIIbβ3-mediated FAK activation occurred in a Src family kinase (SFK)-independent manner whereas G(12/13) pathway caused FAK activation in a SFK and RhoA-dependent manner. A FAK selective inhibitor TAE-226, blocked TXA(2) generation. However, in comparison to WT mice, Pf4-Cre/Fak-Floxed mice did not show any difference in platelet TXA(2) generation. CONCLUSIONS Therefore, we conclude that differential activation of FAK occurs downstream of Integrins and G(12/13) pathways. However, the common effector molecule, possibly a tyrosine kinase downstream of integrins and G(12/13) pathways contributing to TXA(2) generation in platelets remains elusive.
Collapse
|
17
|
Abstract
Upon vascular injury, platelets are activated by adhesion to adhesive proteins, such as von Willebrand factor and collagen, or by soluble platelet agonists, such as ADP, thrombin, and thromboxane A(2). These adhesive proteins and soluble agonists induce signal transduction via their respective receptors. The various receptor-specific platelet activation signaling pathways converge into common signaling events that stimulate platelet shape change and granule secretion and ultimately induce the "inside-out" signaling process leading to activation of the ligand-binding function of integrin α(IIb)β(3). Ligand binding to integrin α(IIb)β(3) mediates platelet adhesion and aggregation and triggers "outside-in" signaling, resulting in platelet spreading, additional granule secretion, stabilization of platelet adhesion and aggregation, and clot retraction. It has become increasingly evident that agonist-induced platelet activation signals also cross talk with integrin outside-in signals to regulate platelet responses. Platelet activation involves a series of rapid positive feedback loops that greatly amplify initial activation signals and enable robust platelet recruitment and thrombus stabilization. Recent studies have provided novel insight into the molecular mechanisms of these processes.
Collapse
Affiliation(s)
- Zhenyu Li
- Department of Medicine, University of Kentucky
| | | | | | - Xiaoping Du
- Department of Pharmacology, University of Illinois at Chicago
| |
Collapse
|
18
|
Deshmukh L, Gorbatyuk V, Vinogradova O. Integrin {beta}3 phosphorylation dictates its complex with the Shc phosphotyrosine-binding (PTB) domain. J Biol Chem 2010; 285:34875-84. [PMID: 20739287 PMCID: PMC2966102 DOI: 10.1074/jbc.m110.159087] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2010] [Revised: 07/30/2010] [Indexed: 01/23/2023] Open
Abstract
Adaptor protein Shc plays a key role in mitogen-activated protein kinase (MAPK) signaling pathway, which can be mediated through a number of different receptors including integrins. By specifically recognizing the tyrosine-phosphorylated integrin β(3), Shc has been shown to trigger integrin outside-in signaling, although the structural basis of this interaction remains nebulous. Here we present the detailed structural analysis of Shc phosphotyrosine-binding (PTB) domain in complex with the bi-phosphorylated β(3)integrin cytoplasmic tail (CT). We show that this complex is primarily defined by the phosphorylation state of the integrin C-terminal Tyr(759), which fits neatly into the classical PTB pocket of Shc. In addition, we have identified a novel binding interface which concurrently accommodates phosphorylated Tyr(747) of the highly conserved NPXY motif of β(3). The structure represents the first snapshot of an integrin cytoplasmic tail bound to a target for mediating the outside-in signaling. Detailed comparison with the known Shc PTB structure bound to a target TrkA peptide revealed some significant differences, which shed new light upon the PTB domain specificity.
Collapse
Affiliation(s)
- Lalit Deshmukh
- From the Department of Pharmaceutical Sciences, School of Pharmacy, and
| | - Vitaliy Gorbatyuk
- the BioNMR Facility, Biotechnology-Bioservices Center, University of Connecticut, Storrs, Connecticut 06269-3092
| | - Olga Vinogradova
- From the Department of Pharmaceutical Sciences, School of Pharmacy, and
| |
Collapse
|
19
|
Bauer NG, Richter-Landsberg C, Ffrench-Constant C. Role of the oligodendroglial cytoskeleton in differentiation and myelination. Glia 2010; 57:1691-705. [PMID: 19455583 DOI: 10.1002/glia.20885] [Citation(s) in RCA: 141] [Impact Index Per Article: 10.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Oligodendrocytes, the myelin-forming cells of the central nervous system, are in culture characterized by an elaborate process network, terminating in flat membranous sheets that are rich in myelin-specific proteins and lipids, and spirally wrap axons forming a compact insulating layer in vivo. By analogy with other cell types, maintenance and stability of these processes, as well as the formation of the myelin sheath, likely rely on a pronounced cytoskeleton consisting of microtubules and microfilaments. While the specialized process of wrapping and compaction forming the myelin sheath is not well understood, considerably more is known about how cytoskeletal organization is mediated by extracellular and intracellular signals and other interaction partners during oligodendrocyte differentiation and myelination. Here, we review the current state of knowledge on the role of the oligodendrocyte cytoskeleton in differentiation with an emphasis on signal transduction mechanisms and will attempt to draw out implications for its significance in myelination.
Collapse
Affiliation(s)
- Nina G Bauer
- MRC Centre for Regenerative Medicine, Centre for Multiple Sclerosis Research, The University of Edinburgh, Queen's Medical Research Institute, Edinburgh EH16 4TJ, United Kingdom.
| | | | | |
Collapse
|
20
|
Anthis NJ, Haling JR, Oxley CL, Memo M, Wegener KL, Lim CJ, Ginsberg MH, Campbell ID. Beta integrin tyrosine phosphorylation is a conserved mechanism for regulating talin-induced integrin activation. J Biol Chem 2009; 284:36700-36710. [PMID: 19843520 PMCID: PMC2794784 DOI: 10.1074/jbc.m109.061275] [Citation(s) in RCA: 99] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2009] [Revised: 10/09/2009] [Indexed: 01/04/2023] Open
Abstract
Integrins are large membrane-spanning receptors fundamental to cell adhesion and migration. Integrin adhesiveness for the extracellular matrix is activated by the cytoskeletal protein talin via direct binding of its phosphotyrosine-binding-like F3 domain to the cytoplasmic tail of the beta integrin subunit. The phosphotyrosine-binding domain of the signaling protein Dok1, on the other hand, has an inactivating effect on integrins, a phenomenon that is modulated by integrin tyrosine phosphorylation. Using full-length tyrosine-phosphorylated (15)N-labeled beta3, beta1A, and beta7 integrin tails and an NMR-based protein-protein interaction assay, we show that talin1 binds to the NPXY motif and the membrane-proximal portion of beta3, beta1A, and beta7 tails, and that the affinity of this interaction is decreased by integrin tyrosine phosphorylation. Dok1 only interacts weakly with unphosphorylated tails, but its affinity is greatly increased by integrin tyrosine phosphorylation. The Dok1 interaction remains restricted to the integrin NPXY region, thus phosphorylation inhibits integrin activation by increasing the affinity of beta integrin tails for a talin competitor that does not form activating membrane-proximal interactions with the integrin. Key residues governing these specificities were identified by detailed structural analysis, and talin1 was engineered to bind preferentially to phosphorylated integrins by introducing the mutation D372R. As predicted, this mutation affects talin1 localization in live cells in an integrin phosphorylation-specific manner. Together, these results indicate that tyrosine phosphorylation is a common mechanism for regulating integrin activation, despite subtle differences in how these integrins interact with their binding proteins.
Collapse
Affiliation(s)
- Nicholas J Anthis
- Department of Biochemistry, University of Oxford, South Parks Road, Oxford OX1 3DR, United Kingdom, California 92093.
| | - Jacob R Haling
- Department of Medicine, University of California, San Diego, La Jolla, California 92093
| | - Camilla L Oxley
- Department of Biochemistry, University of Oxford, South Parks Road, Oxford OX1 3DR, United Kingdom, California 92093
| | - Massimiliano Memo
- Department of Biochemistry, University of Oxford, South Parks Road, Oxford OX1 3DR, United Kingdom, California 92093
| | - Kate L Wegener
- Department of Biochemistry, University of Oxford, South Parks Road, Oxford OX1 3DR, United Kingdom, California 92093
| | - Chinten J Lim
- Department of Medicine, University of California, San Diego, La Jolla, California 92093
| | - Mark H Ginsberg
- Department of Medicine, University of California, San Diego, La Jolla, California 92093
| | - Iain D Campbell
- Department of Biochemistry, University of Oxford, South Parks Road, Oxford OX1 3DR, United Kingdom, California 92093.
| |
Collapse
|
21
|
Shcherbina A, Cooley J, Lutskiy MI, Benarafa C, Gilbert GE, Remold-O'Donnell E. WASP plays a novel role in regulating platelet responses dependent on alphaIIbbeta3 integrin outside-in signalling. Br J Haematol 2009; 148:416-27. [PMID: 19863535 DOI: 10.1111/j.1365-2141.2009.07959.x] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
The most consistent feature of Wiskott Aldrich syndrome (WAS) is profound thrombocytopenia with small platelets. The responsible gene encodes WAS protein (WASP), which functions in leucocytes as an actin filament nucleating agent -yet- actin filament nucleation proceeds normally in patient platelets regarding shape change, filopodia and lamellipodia generation. Because WASP localizes in the platelet membrane skeleton and is mobilized by alphaIIbbeta3 integrin outside-in signalling, we questioned whether its function might be linked to integrin. Agonist-induced alphaIIbbeta3 activation (PAC-1 binding) was normal for patient platelets, indicating normal integrin inside-out signalling. Inside-out signalling (fibrinogen, JON/A binding) was also normal for wasp-deficient murine platelets. However, adherence/spreading on immobilized fibrinogen was decreased for patient platelets and wasp-deficient murine platelets, indicating decreased integrin outside-in responses. Another integrin outside-in dependent response, fibrin clot retraction, involving contraction of the post-aggregation actin cytoskeleton, was also decreased for patient platelets and wasp-deficient murine platelets. Rebleeding from tail cuts was more frequent for wasp-deficient mice, suggesting decreased stabilisation of the primary platelet plug. In contrast, phosphatidylserine exposure, a pro-coagulant response, was enhanced for WASP-deficient patient and murine platelets. The collective results reveal a novel function for WASP in regulating pro-aggregatory and pro-coagulant responses downstream of integrin outside-in signalling.
Collapse
Affiliation(s)
- Anna Shcherbina
- Immune Disease Institute, Harvard Medical School, Boston, MA, USA
| | | | | | | | | | | |
Collapse
|
22
|
Bhattacharya R, Gonzalez AM, Debiase PJ, Trejo HE, Goldman RD, Flitney FW, Jones JCR. Recruitment of vimentin to the cell surface by beta3 integrin and plectin mediates adhesion strength. J Cell Sci 2009; 122:1390-400. [PMID: 19366731 DOI: 10.1242/jcs.043042] [Citation(s) in RCA: 114] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
Much effort has been expended on analyzing how microfilament and microtubule cytoskeletons dictate the interaction of cells with matrix at adhesive sites called focal adhesions (FAs). However, vimentin intermediate filaments (IFs) also associate with the cell surface at FAs in endothelial cells. Here, we show that IF recruitment to FAs in endothelial cells requires beta3 integrin, plectin and the microtubule cytoskeleton, and is dependent on microtubule motors. In CHO cells, which lack beta3 integrin but contain vimentin, IFs appear to be collapsed around the nucleus, whereas in CHO cells expressing beta3 integrin (CHOwtbeta3), vimentin IFs extend to FAs at the cell periphery. This recruitment is regulated by tyrosine residues in the beta3 integrin cytoplasmic tail. Moreover, CHOwtbeta3 cells exhibit significantly greater adhesive strength than CHO or CHO cells expressing mutated beta3 integrin proteins. These differences require an intact vimentin network. Therefore, vimentin IF recruitment to the cell surface is tightly regulated and modulates the strength of adhesion of cells to their substrate.
Collapse
Affiliation(s)
- Ramona Bhattacharya
- Department of Cell and Molecular Biology, Northwestern University Medical School, Chicago, IL 60611, USA
| | | | | | | | | | | | | |
Collapse
|
23
|
Legate KR, Fässler R. Mechanisms that regulate adaptor binding to beta-integrin cytoplasmic tails. J Cell Sci 2009; 122:187-98. [PMID: 19118211 DOI: 10.1242/jcs.041624] [Citation(s) in RCA: 268] [Impact Index Per Article: 17.9] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
Cells recognize and respond to their extracellular environment through transmembrane receptors such as integrins, which physically connect the extracellular matrix to the cytoskeleton. Integrins provide the basis for the assembly of intracellular signaling platforms that link to the cytoskeleton and influence nearly every aspect of cell physiology; however, integrins possess no enzymatic or actin-binding activity of their own and thus rely on adaptor molecules, which bind to the short cytoplasmic tails of integrins, to mediate and regulate these functions. Many adaptors compete for relatively few binding sites on integrin tails, so regulatory mechanisms have evolved to reversibly control the spatial and temporal binding of specific adaptors. This Commentary discusses the adaptor proteins that bind directly to the tails of beta integrins and, using talin, tensin, filamin, 14-3-3 and integrin-linked kinase (ILK) as examples, describes the ways in which their binding is regulated.
Collapse
Affiliation(s)
- Kyle R Legate
- Department of Molecular Medicine, Max Planck Institute of Biochemistry, Martinsried, Germany.
| | | |
Collapse
|
24
|
Abstract
Multiple cell types have an inherent ability to contract the extracellular matrix to which they are attached and grow on. Cells exert contractile forces on a compliant substrate, increase the tension, and deform it. Numerous intracellular as well as environmental factors are involved in determination of cellular contractility, which can be precisely measured by atomic force microscopy, laser tweezers, or other complex apparatus. These, however, are far from being standard equipment in most cell biology labs. Fibrin gels provide a simple and affordable alternative for evaluation of changes in cell contractility by either quantitation of end-point gel contraction or in a dynamic mode by time-lapse imaging. They also provide a flexible system in which the physical properties, such as density and compliance, as well as their biochemical composition can easily be altered to suit the special requirements of various cell types and experimental models.
Collapse
Affiliation(s)
- Sharona Even-Ram
- Hadassah University Hospital, Ein-Kerem, Jerusalem, 91120, Israel.
| |
Collapse
|
25
|
Abstract
alphaIIbbeta3 interaction with fibrinogen promotes Src-dependent platelet spreading in vitro. To determine the consequences of this outside-in signaling pathway in vivo, a "beta3(Delta760-762)" knockin mouse was generated that lacked the 3 C-terminal beta3 residues (arginine-glycine-threonine [RGT]) necessary for alphaIIbbeta3 interaction with c-Src, but retained beta3 residues necessary for talin-dependent fibrinogen binding. beta3(Delta760-762) mice were compared with wild-type beta3(+/+) littermates, beta3(+/-) heterozygotes, and knockin mice where beta3 RGT was replaced by beta1 C-terminal cysteine-glycine-lysine (EGK) to potentially enable signaling by Src kinases other than c-Src. Whereas beta3(+/+), beta3(+/-) and beta3/beta1(EGK) platelets spread and underwent tyrosine phosphorylation normally on fibrinogen, beta3(Delta760-762) platelets spread poorly and exhibited reduced tyrosine phosphorylation of c-Src substrates, including beta3 (Tyr(747)). Unlike control mice, beta3(Delta760-762) mice were protected from carotid artery thrombosis after vessel injury with FeCl(3). Some beta3(Delta760-762) mice exhibited prolonged tail bleeding times; however, none demonstrated spontaneous bleeding, excess bleeding after surgery, fecal blood loss, or anemia. Fibrinogen binding to beta3(Delta760-762) platelets was normal in response to saturating concentrations of protease-activated receptor 4 or glycoprotein VI agonists, but responses to adenosine diphosphate were impaired. Thus, deletion of beta3 RGT disrupts c-Src-mediated alphaIIbbeta3 signaling and confers protection from arterial thrombosis. Consequently, targeting alphaIIbbeta3 signaling may represent a feasible antithrombotic strategy.
Collapse
|
26
|
Group IVA cytosolic phospholipase A2 (cPLA2alpha) and integrin alphaIIbbeta3 reinforce each other's functions during alphaIIbbeta3 signaling in platelets. Blood 2008; 113:447-57. [PMID: 18840708 DOI: 10.1182/blood-2008-06-162032] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Group IVA cytosolic phospholipase A(2) (cPLA(2)alpha) catalyzes release of arachidonic acid from glycerophospholipids, leading to thromboxane A(2) (TxA(2)) production. Some platelet agonists stimulate cPLA(2)alpha, but others require fibrinogen binding to alphaIIbbeta3 to elicit TxA(2). Therefore, relationships between cPLA(2)alpha and alphaIIbbeta3 were examined. cPLA(2)alpha and a cPLA(2)alpha binding partner, vimentin, coimmunoprecipitated with alphaIIbbeta3 from platelets, independent of fibrinogen binding. Studies with purified proteins and with recombinant proteins expressed in CHO cells determined that the interaction between cPLA(2)alpha and alphaIIbbeta3 was indirect and was dependent on the alphaIIb and beta3 cytoplasmic tails. Fibrinogen binding to alphaIIbbeta3 caused an increase in integrin-associated cPLA(2)alpha activity in normal platelets, but not in cPLA(2)alpha-deficient mouse platelets or in human platelets treated with pyrrophenone, a cPLA(2)alpha inhibitor. cPLA(2)alpha activation downstream of alphaIIbbeta3 had functional consequences for platelets in that it was required for fibrinogen-dependent recruitment of activated protein kinase Cbeta to the alphaIIbbeta3 complex and for platelet spreading. Thus, cPLA(2)alpha and alphaIIbbeta3 interact to reinforce each other's functions during alphaIIbbeta3 signaling. This provides a plausible explanation for the role of alphaIIbbeta3 in TxA(2) formation and in the defective hemostatic function of mouse or human platelets deficient in cPLA(2)alpha.
Collapse
|
27
|
Chen JJ, Su XY, Xi XD, Lin LP, Ding J, Lu H. Fibrinogen interaction of CHO cells expressing chimeric alphaIIb/alphavbeta3 integrin. Acta Pharmacol Sin 2008; 29:204-10. [PMID: 18215349 DOI: 10.1111/j.1745-7254.2008.00723.x] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022] Open
Abstract
AIM The molecular mechanisms of the affinity regulation of alphavbeta3 integrin are important in tumor development, wound repairing, and angiogenesis. It has been established that the cytoplasmic domains of alphavbeta3 integrin play an important role in integrin-ligand affinity regulation. However, the relationship of structure-function within these domains remains unclear. METHODS The extracellular and transmembrane domain of alphaIIb was fused to the alphav integrin cytoplasmic domain, and the chimeric alpha subunit was coexpressed in Chinese hamster ovary (CHO) cells with the wild-type beta3 subunit or with 3 mutant beta3 sequences bearing truncations at the positions of T741, Y747, and F754, respectively. The CHO cells expressing these recombinant integrins were tested for soluble fibrinogen binding and the cell adhesion and spreading on immobilized fibrinogen. RESULTS All 4 types of integrins bound soluble fibrinogen in the absence of agonist stimulation, and only the cells expressing the chimeric alpha subunit with the wild-type beta3 subunit, but not those with truncated beta3, could adhere to and spread on immobilized fibrinogen. CONCLUSION The substitution alphaIIb at the cytoplasmic domain with the alphav cytoplasmic sequence rendered the extracellular alphaIIbbeta3 a constitutively activated conformation for ligands without the need of pinside-outq signals. Our results also indicated that the COOH-terminal sequence of beta3 might play a key role in integrin alphaIIb/alphavbeta3-mediated cell adhesion and spreading on immobilized fibrinogen. The cells expressing alphaIIb/alphavbeta3 have enormous potential for facilitating drug screening for antagonists either to alphavbeta3 intracellular interactions or to alphaIIbbeta3 receptor functions.
Collapse
Affiliation(s)
- Juan-juan Chen
- Division of Antitumor Pharmacology, State Key Laboratory of Drug Research, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai 201203, China
| | | | | | | | | | | |
Collapse
|
28
|
Clemmons DR, Maile LA, Ling Y, Yarber J, Busby WH. Role of the integrin alphaVbeta3 in mediating increased smooth muscle cell responsiveness to IGF-I in response to hyperglycemic stress. Growth Horm IGF Res 2007; 17:265-270. [PMID: 17412627 PMCID: PMC2366026 DOI: 10.1016/j.ghir.2007.01.004] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
Abstract
Under usual conditions, the role of IGF-I in vascular cell types is to maintain cellular protein synthesis and cell size, and even excess IGF-I does not stimulate proliferation. In pathophysiologic states, such as hyperglycemia, smooth muscle cells (SMC) dedifferentiate and change their responsiveness to IGF-I. During hyperglycemia IGF-I stimulates both SMC migration and proliferation. Our laboratory has investigated the molecular mechanism by which this change is mediated. During hyperglycemia SMC secrete increased concentrations of thrombospondin, vitronectin and osteopontin, ligands for the integrin alphaVbeta3. Activation of alphaVbeta3 stimulates recruitment of a tyrosine phosphatase, SHP-2. Exposure of SMC to IGF-I results in phosphorylation of the transmembrane protein, SHPS-1, which provides a docking site for alphaVbeta3-associated SHP-2. After IGF-I stimulation SHP-2 associates with Src kinase, which associates with the signaling protein Shc. Src phosphorylates Shc, resulting in activation of MAP kinases, which are necessary both for stimulation of cell proliferation and migration. Blocking activation of alphaVbeta3 results in an inability of IGF-I to stimulate Shc phosphorylation. Under conditions of normoglycemia, there are insufficient alphaVbeta3 ligands to recruit SHP-2, and no increase in Shc phosphorylation can be demonstrated in SMC. In contrast, if alphaVbeta3 ligands are added to cells in normal glucose, the signaling events that are necessary for Shc phosphorylation can be reconstituted. Therefore when SMC are exposed to normal glucose they are protected from excessive stimulation of mitogenesis by IGF-I. With hyperglycemia there is a marked increased in alphaVbeta3 ligands and Shc phosphorylation in response to IGF-I is sustained. These findings indicate that in SMC hyperglycemic stress leads to altered IGF-I signaling, which allows the cells to undergo a mitogenic response, and which may contribute to the development of atherosclerosis.
Collapse
Affiliation(s)
- David R Clemmons
- Department of Medicine, Division of Endocrinology, University of North Carolina at Chapel Hill, School of Medicine, Chapel Hill, NC 27599, USA.
| | | | | | | | | |
Collapse
|
29
|
Abstract
Integrin alpha(IIb)beta(3) plays a critical role in platelet aggregation, a central response in hemostasis and thrombosis. This function of alpha(IIb)beta(3) depends upon a transition from a resting to an activated state such that it acquires the capacity to bind soluble ligands. Diverse platelet agonists alter the cytoplasmic domain of alpha(IIb)beta(3) and initiate a conformational change that traverses the transmembrane region and ultimately triggers rearrangements in the extracellular domain to permit ligand binding. The membrane-proximal regions of alpha(IIb) and beta(3) cytoplasmic tails, together with the transmembrane segments of the subunits, contact each other to form a complex which restrains the integrin in the resting state. It is unclasping of this complex that induces integrin activation. This clasping/unclasping process is influenced by multiple cytoplasmic tail binding partners. Among them, talin appears to be a critical trigger of alpha(IIb)beta(3) activation, but other binding partners, which function as activators or suppressors, are likely to act as co-regulators of integrin activation.
Collapse
Affiliation(s)
- Y-Q Ma
- Department of Molecular Cardiology, Joseph J. Jacobs Center for Thrombosis and Vascular Biology, Lerner Research Institute, Cleveland Clinic, Cleveland, OH, USA
| | | | | |
Collapse
|
30
|
|
31
|
|
32
|
|
33
|
Feng S, Lu X, Reséndiz JC, Kroll MH. Pathological shear stress directly regulates platelet αIIbβ3signaling. Am J Physiol Cell Physiol 2006; 291:C1346-54. [PMID: 16822941 DOI: 10.1152/ajpcell.00559.2005] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
Integrin mechanotransduction is a ubiquitous biological process. Mechanical forces are transduced transmembranously by an integrin's ligand-bound extracellular domain through its β-subunit's cytoplasmic domain connected to the cytoskeleton. This often culminates in the activation of tyrosine kinases directing cell responses. The delicate balance between hemostasis and thrombosis requires exquisitely fine-tuned integrin function, and balance is maintained in vivo despite that the major platelet integrin αIIbβ3is continuously subjected to frictional or shearing forces generated by laminar blood flow. To test the hypothesis that platelet function is regulated by the direct effects of mechanical forces on αIIbβ3, we examined αIIbβ3/cytoskeletal interactions in human platelets exposed to shear stress in a cone-plate viscometer. We observed that α-actinin, myosin heavy chain, and Syk coimmunoprecipitate with αIIbβ3in resting platelets and that 120 dyn/cm2shear stress leads to their disassociation from αIIbβ3. Shear-induced disassociation of α-actinin and myosin heavy chain from the β3tail is unaffected by blocking von Willebrand factor (VWF) binding to glycoprotein (Gp) Ib-IX-V but abolished by blocking VWF binding to αIIbβ3. Syk's disassociation from β3is inhibited when VWF binding to either GpIb-IX-V or αIIbβ3is blocked. Shear stress-induced phosphorylation of SLP-76 and its association with tyrosine-phosphorylated adhesion and degranulation-promoting adapter protein are inhibited by blocking ligand binding to αIIbβ3but not by blocking ligand binding to GpIb-IX-V. Chinese hamster ovary cells expressing αIIbβ3with β3truncated of its cytoskeletal binding domains demonstrate diminished shear-dependent adhesion and cohesion. These results support the hypothesis that shear stress directly modulates αIIbβ3function and suggest that shear-induced αIIbβ3-mediated signaling contributes to the regulation of platelet aggregation by directing the release of constraining cytoskeletal elements from the β3-tail.
Collapse
Affiliation(s)
- Shuju Feng
- Michael E. DeBakey Veterans Affairs Medical Center, Baylor College of Medicine and Rice University, Houston, Texas 77030 , USA
| | | | | | | |
Collapse
|
34
|
Suzuki-Inoue K, Hughes CE, Inoue O, Kaneko M, Cuyun-Lira O, Takafuta T, Watson SP, Ozaki Y. Involvement of Src kinases and PLCgamma2 in clot retraction. Thromb Res 2006; 120:251-8. [PMID: 17055557 PMCID: PMC1884692 DOI: 10.1016/j.thromres.2006.09.003] [Citation(s) in RCA: 54] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2006] [Revised: 09/08/2006] [Accepted: 09/12/2006] [Indexed: 11/18/2022]
Abstract
The integrin αIIbβ3 plays a critical role in mediating clot retraction by platelets which is important in vivo in consolidating thrombus formation. Actin–myosin interaction is essential for clot retraction. In the present study, we demonstrate that the structurally distinct Src kinase inhibitors, PP2 and PD173952, significantly reduced the rate of clot retraction, but did not prevent it reaching completion. This effect was accompanied by abolition of αIIbβ3-dependent protein tyrosine phosphorylation, including PLCγ2. A role for PLCγ2 in mediating clot retraction was demonstrated using PLCγ2-deficient murine platelets. Furthermore, platelet adhesion to fibrinogen leads to MLC phosphorylation through a pathway that is inhibited by PP2 and by the PLC inhibitor, U73122. These results demonstrate a partial role for Src kinase-dependent activation of PLCγ2 and MLC phosphorylation in mediating clot retraction downstream of integrin αIIbβ3.
Collapse
Affiliation(s)
- Katsue Suzuki-Inoue
- Department of Clinical and Laboratory Medicine, Faculty of Medicine, Yamanashi University, 1110 Shimokato, Chuo, Yamanashi, 409-3898, Japan.
| | | | | | | | | | | | | | | |
Collapse
|
35
|
Xi X, Flevaris P, Stojanovic A, Chishti A, Phillips DR, Lam SCT, Du X. Tyrosine phosphorylation of the integrin beta 3 subunit regulates beta 3 cleavage by calpain. J Biol Chem 2006; 281:29426-30. [PMID: 16935858 DOI: 10.1074/jbc.c600039200] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Outside-in signaling of beta(3) integrins induces and requires phosphorylation at tyrosine 747 (Tyr(747)) and tyrosine 759 (Tyr(759)) of the beta(3) subunit, but the mechanism for this requirement is unclear. On the other hand, a key consequence of integrin signaling, cell spreading, is inhibited by calpain cleavage of beta(3) cytoplasmic domain. Here we show that beta(3) tyrosine phosphorylation inhibits calpain cleavage. Mutating both tyrosines to phenylalanine sensitizes beta(3) to calpain cleavage. Furthermore, phosphorylation at Tyr(747) and Tyr(759) of beta(3) in the focal adhesion sites and the leading edge of spreading platelets was differentially regulated. Selective dephosphorylation of Tyr(759) is associated with calpain cleavage at Tyr(759). Thus, one mechanism by which tyrosine phosphorylation promotes integrin signaling and cell spreading is its inhibition of calpain cleavage of the beta(3) cytoplasmic domain.
Collapse
Affiliation(s)
- Xiaodong Xi
- Department of Pharmacology, University of Illinois, Chicago, Illinois 60612, USA
| | | | | | | | | | | | | |
Collapse
|
36
|
Pylayeva Y, Giancotti FG. Development requires activation but not phosphorylation of beta1 integrins. Genes Dev 2006; 20:1057-60. [PMID: 16651652 DOI: 10.1101/gad.1432006] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Affiliation(s)
- Yuliya Pylayeva
- Cell Biology Program, Memorial Sloan-Kettering Cancer Center, New York, New York, USA.
| | | |
Collapse
|
37
|
Tanentzapf G, Martin-Bermudo MD, Hicks MS, Brown NH. Multiple factors contribute to integrin-talin interactions in vivo. J Cell Sci 2006; 119:1632-44. [PMID: 16569666 DOI: 10.1242/jcs.02859] [Citation(s) in RCA: 51] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The cytoplasmic protein talin is an essential part of the integrin-cytoskeleton link. We characterized the interaction between integrin and two conserved regions of talin, the N-terminal ;head' domain and the C-terminus, which includes the I/LWEQ domain, within the living organism. Green-fluorescent-protein-tagged head and C-terminal domains were recruited to integrin adhesion sites. Both required integrins for recruitment, but the C-terminal domain also required endogenous talin, showing it was not recruited directly by integrins. We used chimeric transmembrane proteins containing the cytoplasmic domain of the integrin beta subunit to examine the integrin-talin head interaction. Monomeric chimeric proteins did not recruit talin head, whereas dimeric chimeras efficiently recruited it and caused a strong inhibition of integrin-mediated adhesion. These chimeras recruited surprisingly few integrin-associated proteins, indicating that recruitment of talin did not initiate a cascade of recruitment. Mutagenesis of the integrin cytoplasmic domain, within the chimera, showed the dominant-negative inhibition was not due to talin sequestration alone and that additional interactions are required.
Collapse
Affiliation(s)
- Guy Tanentzapf
- The Wellcome Trust/Cancer Research UK Gurdon Institute and Department of Anatomy, University of Cambridge, Tennis Court Road, Cambridge, CB2 1QN, UK
| | | | | | | |
Collapse
|
38
|
Cayrol C, Clerc P, Bertrand C, Gigoux V, Portolan G, Fourmy D, Dufresne M, Seva C. Cholecystokinin-2 receptor modulates cell adhesion through beta 1-integrin in human pancreatic cancer cells. Oncogene 2006; 25:4421-8. [PMID: 16547500 DOI: 10.1038/sj.onc.1209484] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Several lines of evidence suggest that gastrin and the CCK-2 receptor (CCK2R) could contribute to pancreatic carcinogenesis by modulating processes such as proliferation, cell adhesion or migration. In the current study, we used a 'cancer gene array' and identified beta1-integrin subunit as a new gastrin-regulated gene in human pancreatic cancer cells. We also demonstrated that Src family kinases and the phosphatidylinositol-3-kinase (PI-3-kinase) pathway play a crucial role in the expression of beta1-integrin induced by gastrin. Our results also showed that gastrin modulates cell-substrate adhesion via beta1-integrin. Indeed, using blocking anti-beta1-integrin monoclonal antibodies, we completely reversed the increase in cell-substrate adhesion induced by gastrin. In addition, we observed that in response to gastrin, beta1-integrin is tyrosine phosphorylated by Src family kinases and associates with paxillin, a scaffold protein involved in focal adhesion and integrin signalling. This mechanism might be involved in gastrin-induced cell adhesion. Moreover, we showed in vivo that targeted CCK2R expression in the pancreas of Elas-CCK2 mice leads to the overexpression of beta1-integrin. This process may contribute to pancreatic tumour development observed in these transgenic animals.
Collapse
Affiliation(s)
- C Cayrol
- INSERM U 531, IFR 31, Institut Louis Bugnard, Toulouse, France
| | | | | | | | | | | | | | | |
Collapse
|
39
|
Brass LF, Jiang H, Wu J, Stalker TJ, Zhu L. Contact-dependent signaling events that promote thrombus formation. Blood Cells Mol Dis 2006; 36:157-61. [PMID: 16473534 DOI: 10.1016/j.bcmd.2005.12.015] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2005] [Accepted: 12/06/2005] [Indexed: 01/21/2023]
Abstract
There is increasing evidence that formation of a stable hemostatic plug requires adhesive and signaling events that continue beyond the onset of platelet aggregation. These events are facilitated and, in some cases, made possible, by the persistent close contacts between platelets that can only occur when platelets begin to aggregate. Participants include integrins and other cell adhesion molecules, secreted agonists, receptor tyrosine kinases, and protein fragments that are shed from the surface of activated platelets. Collectively, these molecules promote the continued growth and stability of the hemostatic plug.
Collapse
Affiliation(s)
- Lawrence F Brass
- Department of Medicine, University of Pennsylvania, Room 915 BRB-II, 421 Curie Blvd., Philadelphia, PA 19104, USA.
| | | | | | | | | |
Collapse
|
40
|
Brass LF, Zhu L, Stalker TJ. Minding the gaps to promote thrombus growth and stability. J Clin Invest 2006; 115:3385-92. [PMID: 16322784 PMCID: PMC1297259 DOI: 10.1172/jci26869] [Citation(s) in RCA: 115] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
Abstract
Efforts to understand the role of platelets in hemostasis and thrombosis have largely focused on the earliest events of platelet activation, those that lead to aggregation. Although much remains to be learned about those early events, this Review examines a later series of events: the interactions between platelets that can only occur once aggregation has begun, bringing platelets into close contact with each other, creating a protected environment in the gaps between aggregated platelets, and fostering the continued growth and stability of the hemostatic plug.
Collapse
Affiliation(s)
- Lawrence F Brass
- Department of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania 19104, USA.
| | | | | |
Collapse
|
41
|
Butler B, Gao C, Mersich AT, Blystone SD. Purified Integrin Adhesion Complexes Exhibit Actin-Polymerization Activity. Curr Biol 2006; 16:242-51. [PMID: 16461277 DOI: 10.1016/j.cub.2005.12.033] [Citation(s) in RCA: 58] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2005] [Revised: 12/14/2005] [Accepted: 12/15/2005] [Indexed: 11/19/2022]
Abstract
BACKGROUND Cell adhesion and motility are accomplished through a functional linkage of the extracellular matrix with the actin cytoskeleton via adhesion complexes composed of integrin receptors and associated proteins. To determine whether this linkage is attained actively or passively, we isolated integrin complexes from nonadherent hematopoietic cells and determined their influence on the polymerization of actin. RESULTS We observed that alpha(V)beta3 complexes are capable of dramatically accelerating the rate of actin assembly, resulting in actin fibers tethered at their growing ends by clustered integrins. The ability to enhance actin polymerization was dependent upon Arg-Gly-Asp-ligand-induced beta3 tyrosine phosphorylation, agonist-induced cellular activation, sequestration of Diaphanous formins, and clustering of the receptor. CONCLUSIONS These results suggest that adhesion complexes actively promote actin assembly from their cytosolic face in order to establish a mechanical linkage with the extracellular matrix.
Collapse
Affiliation(s)
- Boyd Butler
- Department of Cell and Developmental Biology, SUNY Upstate Medical University, 750 East Adams St, Syracuse, New York 13210, USA
| | | | | | | |
Collapse
|
42
|
Abstract
PURPOSE OF REVIEW Over the past few years, a large portion of platelet research has focused on intracellular signaling events that contribute to stable platelet adhesion and aggregation. RECENT FINDINGS Studies of knockout mice have suggested critical roles for several previously unappreciated signaling molecules including phosphatidylinositol 3-kinase, the exchange factor CalDAG-GEFI, and the small GTPase Rap1b. These proteins may function to remodel the platelet cytoskeleton and thereby regulate both adhesion and aggregation. The abundant cytoskeletal protein talin appears to be a key regulator of the platelet integrin alphaIIbbeta3. Recent evidence suggests that talin binding to the cytoplasmic tail of beta3 promotes integrin oligomerization, thereby increasing the binding avidity the alphaIIbbeta3 complex for fibrinogen. SUMMARY The identification of platelet signaling pathways not only has clinical implications for diagnosis, but perhaps more importantly for rationale drug design. Aspirin, dipyridamole (Persantine), and thienopyridines (ticlopidine and clopidogrel) are all examples of agents that specifically target discrete platelet signaling pathways. These drugs have already been proven to be beneficial in the treatment of cardiovascular disease. Novel agents that target newly identified signaling pathways hold promise of greater specificity and efficacy.
Collapse
Affiliation(s)
- Charles S Abrams
- University of Pennsylvania, Room 912, Biomedical Research Building II/III, 421 Curie Blvd., Philadelphia, PA 19104, USA.
| |
Collapse
|
43
|
Abstract
This review summarizes recent developments in our understanding of the molecular basis of platelet activation by two distinct types of surface receptor, the immunoglobulin GPVI, and the integrin alphaIIb beta3 (also known as GPIIbIIIa). These two classes of receptor signal through similar yet distinct tyrosine kinase-based signaling cascades leading to activation of phospholipase C gamma2. The significance of these signaling cascades in platelet adhesion and platelet aggregation at arterial rates of shear is discussed.
Collapse
Affiliation(s)
- S P Watson
- Division of Medical Sciences, Centre for Cardiovascular Sciences, Institute of Biomedical Research, The Medical School, University of Birmingham, Birmingham, UK.
| | | | | | | |
Collapse
|
44
|
Abstract
The development and integrity of the cardiovascular system depends on integrins, a family of adhesion receptors, vitally important for homeostasis of animal species from fruit fly to man. Integrins are critical players in cell migration, cell adhesion, cell cycle progression, differentiation, and apoptosis. Consequently, integrins have a major impact on the patterning and functions of the blood and cardiovascular system. Integrins undergo conformational changes, which alter their affinity for ligands through a process operationally defined as integrin activation. Integrin activation is important for platelet aggregation, leukocyte extravasation, and cell adhesion and migration, thus influencing such processes as hemostasis, inflammation and angiogenesis. Recently, a series of studies have begun to define the mechanism of integrin activation by demonstrating that binding of a cytoskeletal protein, talin, to integrin beta subunit cytoplasmic tail is a last common step in integrin activation. These findings indicate that talin is likely to be at the center of converging signaling pathways regulating integrin activation.
Collapse
Affiliation(s)
- B I Ratnikov
- Department of Medicine, University of California San Diego, La Jolla, CA 92093-0726, USA
| | | | | |
Collapse
|
45
|
Prévost N, Woulfe DS, Jiang H, Stalker TJ, Marchese P, Ruggeri ZM, Brass LF. Eph kinases and ephrins support thrombus growth and stability by regulating integrin outside-in signaling in platelets. Proc Natl Acad Sci U S A 2005; 102:9820-5. [PMID: 15994237 PMCID: PMC1174973 DOI: 10.1073/pnas.0404065102] [Citation(s) in RCA: 116] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The ability of activated platelets to adhere to each other at sites of vascular injury depends on the integrin alpha(IIb)beta(3). However, as aggregation continues, other signaling and adhesion molecules can contribute as well. We have previously shown that human platelets express on their surface the Eph receptor kinases EphA4 and EphB1 and the Eph kinase ligand ephrinB1. We now show that EphA4 is physically associated with alpha(IIb)beta(3) in resting platelets, increases its surface expression when platelets are activated, and colocalizes with alpha(IIb)beta(3) at sites of contact between platelets. We also show that Eph/ephrin interactions can support the stable accumulation of platelets on collagen under flow and contribute to postengagement "outside-in" signaling through alpha(IIb)beta(3) by stabilizing platelet aggregates and facilitating tyrosine phosphorylation of the beta(3) cytoplasmic domain. beta(3) phosphorylation allows myosin to bind to alpha(IIb)beta(3) and clot retraction to occur. The data support a model in which the onset of aggregation permits Eph/ephrin interactions to occur, after which signaling downstream from ephrinB1 and its receptors favors continued growth and stability of the thrombus by several mechanisms, including positive effects on outside-in signaling through alpha(IIb)beta(3).
Collapse
Affiliation(s)
- Nicolas Prévost
- Department of Medicine, and Center for Experimental Therapeutics, University of Pennsylvania, 421 Curie Boulevard, Philadelphia, PA 19104, USA
| | | | | | | | | | | | | |
Collapse
|
46
|
Yamniuk AP, Vogel HJ. Calcium- and magnesium-dependent interactions between calcium- and integrin-binding protein and the integrin alphaIIb cytoplasmic domain. Protein Sci 2005; 14:1429-37. [PMID: 15883187 PMCID: PMC2253396 DOI: 10.1110/ps.041312805] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Abstract
Calcium- and integrin-binding protein (CIB) is a small EF-hand calcium-binding protein that is involved in hemostasis through its interaction with the alphaIIb cytoplasmic domain of integrinalphaIIbbeta(3). We have previously demonstrated that CIB lacks structural stability in the absence of divalent metal ions but that it acquires a well-folded conformation upon addition of Ca(2+) or Mg(2+). Here, we have used fluorescence spectroscopy, NMR spectroscopy, and isothermal titration calorimetry to demonstrate that both Ca(2+)-bound CIB (Ca(2+)-CIB) and the Mg(2+)-bound protein (Mg(2+)-CIB) bind with high affinity and through a similar mechanism to alphaIIb cytoplasmic domain peptides, but that metal-free CIB (apo-CIB) binds in a different manner. The interactions are thermodynamically distinct for Ca(2+)-CIB and Mg(2+)-CIB, but involve hydrophobic interactions in each case. Since the Mg(2+) concentration inside the cell is sufficient to saturate CIB at all times, our results imply that CIB would be capable of binding to the alphaIIb cytoplasmic domain independent of an intracellular Ca(2+) stimulus in vivo. This raises the question of whether CIB can act as a Ca(2+) sensor in alphaIIbbeta(3) signaling or if other regulatory mechanisms such as fibrinogen-induced conformational changes in alphaIIbbeta(3), post-translational modifications, or the binding of other accessory proteins mediate the interactions between CIB and alphaIIbbeta(3). Differences in NMR spectra do suggest, however, that Ca(2+)-binding to the Mg(2+)- CIB-alphaIIb complex induces subtle structural changes that could further modulate the activity of alphaIIbbeta(3).
Collapse
Affiliation(s)
- Aaron P Yamniuk
- Structural Biology Research Group, Department of Biological Sciences, University of Calgary, 2500 University Drive NW, Calgary, AB, Canada T2N 1N4
| | | |
Collapse
|
47
|
Abstract
Extracellular matrix (ECM) molecules and growth factors have a crucial role in the signalling that controls cell behaviour during development. Integrins, which are cell-surface receptors for ECM molecules, and growth factor receptors cooperate with each other to regulate this signalling by several mechanisms. In particular, direct interactions between the integrin and growth factor receptors themselves, which often occur within a single macromolecular complex, amplify signalling by mechanisms that include posttranslational modifications and integrin shape changes that are related to activation. As a result, growth factor concentrations in the physiological range, which are too low to initiate signalling alone, do so in the presence of the ECM, enabling integrins to control the time and space of growth factor signalling.
Collapse
Affiliation(s)
- Charles ffrench-Constant
- Departments of Pathology and Medical Genetics, and Cambridge Centre for Brain Repair, University of Cambridge, Tennis Court Road, Cambridge CB2 1QP, UK.
| | | |
Collapse
|
48
|
Beauvais DM, Burbach BJ, Rapraeger AC. The syndecan-1 ectodomain regulates alphavbeta3 integrin activity in human mammary carcinoma cells. ACTA ACUST UNITED AC 2004; 167:171-81. [PMID: 15479743 PMCID: PMC2172512 DOI: 10.1083/jcb.200404171] [Citation(s) in RCA: 204] [Impact Index Per Article: 10.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
The αvβ3 integrin participates in cell morphogenesis, growth factor signaling, and cell survival. Activation of the integrin is central to these processes and is influenced by specific ECM components, which engage both integrins and syndecans. This paper demonstrates that the αvβ3 integrin and syndecan-1 (S1) are functionally coupled. The integrin is dependent on the syndecan to become activated and to mediate signals required for MDA-MB-231 and MDA-MB-435 human mammary carcinoma cell spreading on vitronectin or S1-specific antibody. Coupling of the syndecan to αvβ3 requires the S1 ectodomain (ED), as ectopic expression of glycosylphosphatidylinositol-linked S1ED enhances αvβ3 recognition of vitronectin; and treatments that target this domain, including competition with recombinant S1ED protein or anti-S1ED antibodies, mutation of the S1ED, or down-regulation of S1 expression by small-interfering RNAs, disrupt αvβ3-dependent cell spreading and migration. Thus, S1 is likely to be a critical regulator of many cellular behaviors that depend on activated αvβ3 integrins.
Collapse
Affiliation(s)
- DeannaLee M Beauvais
- Department of Pathology and Laboratory Medicine, University of Wisconsin-Madison, Madison, WI 53706, USA
| | | | | |
Collapse
|
49
|
Higashi T, Yoshioka A, Shirakawa R, Tabuchi A, Nishioka H, Kita T, Horiuchi H. Direct demonstration of involvement of the adaptor protein ShcA in the regulation of Ca2+-induced platelet aggregation. Biochem Biophys Res Commun 2004; 322:700-4. [PMID: 15325286 DOI: 10.1016/j.bbrc.2004.07.177] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2004] [Indexed: 10/26/2022]
Abstract
Platelet aggregation is mediated by conformational change of integrin alpha(IIb)beta(3). Tyrosine-phosphorylation of cytoplasmic domain of beta(3) upon platelet activation has been demonstrated to play a critical role in this process. Recently, the adaptor protein ShcA has been shown to bind to the tyrosine-phosphorylated beta(3), while it remains open whether ShcA plays any role in platelet aggregation. Here, we show that ShcA bound to tyrosine-phosphorylated beta(3)-tail peptide through its phosphotyrosine-binding domain in vitro. Then, we examined the involvement of ShcA in platelet aggregation by a previously established in vitro assay using platelets permeabilized with streptolysin-O, where exogenous addition of platelet cytosol is required for reconstitution of the Ca(2+)-induced aggregation. When ShcA was specifically depleted with anti-ShcA antibody from the cytosol, this ShcA-depleted cytosol lost the aggregation-supporting activity, which was rescued by addition of purified recombinant ShcA. Thus, ShcA is essential for the Ca(2+)-induced platelet aggregation.
Collapse
Affiliation(s)
- Tomohito Higashi
- Department of Cardiovascular Medicine, Graduate School of Medicine, Kyoto University, Kyoto 606-8507, Japan
| | | | | | | | | | | | | |
Collapse
|
50
|
Shattil SJ, Newman PJ. Integrins: dynamic scaffolds for adhesion and signaling in platelets. Blood 2004; 104:1606-15. [PMID: 15205259 DOI: 10.1182/blood-2004-04-1257] [Citation(s) in RCA: 404] [Impact Index Per Article: 20.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023] Open
Abstract
The major platelet integrin, alphaIIbbeta3, is required for platelet interactions with proteins in plasma and the extracellular matrices (ECMs) that are essential for platelet adhesion and aggregation during hemo stasis and arterial thrombosis. Lig and binding to alphaIIbbeta3 is controlled by inside-out signals that modulate receptor conformation and clustering. In turn, ligand binding triggers outside-in signals through alphaIIbbeta3 that, when disrupted, can cause a bleeding diathesis. In the past 5 years there has been an explosion of knowledge about the structure and function ofalphaIIbbeta3 and the related integrin, alphaVbeta3. These developments are discussed here, and current models of bidirectional alphaIIbbeta3 signaling are presented as frameworks for future investigations. An understanding that alphaIIbbeta3 functions as a dynamic molecular scaffold for extracellular and intracellular proteins has translated into diagnostic and therapeutic insights relevant to hematology and cardiovascular medicine, and further advances can be anticipated.
Collapse
Affiliation(s)
- Sanford J Shattil
- Department of Cell Biology, The Scripps Research Institute, La Jolla, CA, USA.
| | | |
Collapse
|