1
|
Guan IA, Liu JST, Sawyer RC, Li X, Jiao W, Jiramongkol Y, White MD, Hagimola L, Passam FH, Tran DP, Liu X, Schoenwaelder SM, Jackson SP, Payne RJ, Liu X. Integrating Phenotypic and Chemoproteomic Approaches to Identify Covalent Targets of Dietary Electrophiles in Platelets. ACS Cent Sci 2024; 10:344-357. [PMID: 38435523 PMCID: PMC10906253 DOI: 10.1021/acscentsci.3c00822] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 07/05/2023] [Revised: 12/24/2023] [Accepted: 12/28/2023] [Indexed: 03/05/2024]
Abstract
A large variety of dietary phytochemicals has been shown to improve thrombosis and stroke outcomes in preclinical studies. Many of these compounds feature electrophilic functionalities that potentially undergo covalent addition to the sulfhydryl side chain of cysteine residues within proteins. However, the impact of such covalent modifications on the platelet activity and function remains unclear. This study explores the irreversible engagement of 23 electrophilic phytochemicals with platelets, unveiling the unique antiplatelet selectivity of sulforaphane (SFN). SFN impairs platelet responses to adenosine diphosphate (ADP) and a thromboxane A2 receptor agonist while not affecting thrombin and collagen-related peptide activation. It also substantially reduces platelet thrombus formation under arterial flow conditions. Using an alkyne-integrated probe, protein disulfide isomerase A6 (PDIA6) was identified as a rapid kinetic responder to SFN. Mechanistic profiling studies revealed SFN's nuanced modulation of PDIA6 activity and substrate specificity. In an electrolytic injury model of thrombosis, SFN enhanced the thrombolytic activity of recombinant tissue plasminogen activator (rtPA) without increasing blood loss. Our results serve as a catalyst for further investigations into the preventive and therapeutic mechanisms of dietary antiplatelets, aiming to enhance the clot-busting power of rtPA, currently the only approved therapeutic for stroke recanalization that has significant limitations.
Collapse
Affiliation(s)
- Ivy A. Guan
- School
of Chemistry, Faculty of Science, The University
of Sydney, Sydney, New South Wales 2006, Australia
- The
Heart Research Institute, The University
of Sydney, Newtown, New South Wales 2042, Australia
| | - Joanna S. T. Liu
- The
Heart Research Institute, The University
of Sydney, Newtown, New South Wales 2042, Australia
- School
of Medical Sciences, Faculty of Medicine and Health, The University of Sydney, Sydney, New South Wales 2006, Australia
| | - Renata C. Sawyer
- School
of Chemistry, Faculty of Science, The University
of Sydney, Sydney, New South Wales 2006, Australia
- The
Heart Research Institute, The University
of Sydney, Newtown, New South Wales 2042, Australia
| | - Xiang Li
- Department
of Medicine, Washington University in St.
Louis, St. Louis, Missouri 63110, United States
- McDonnell
Genome Institute, Washington University
in St. Louis, St. Louis, Missouri 63108, United States
| | - Wanting Jiao
- Ferrier Research
Institute, Victoria University of Wellington, Wellington 6140, New Zealand
- Maurice Wilkins Centre for Molecular Biodiscovery, Auckland 1142, New Zealand
| | - Yannasittha Jiramongkol
- School
of Chemistry, Faculty of Science, The University
of Sydney, Sydney, New South Wales 2006, Australia
- Charles
Perkins Centre, The University of Sydney, Sydney, New South Wales 2006, Australia
| | - Mark D. White
- School
of Chemistry, Faculty of Science, The University
of Sydney, Sydney, New South Wales 2006, Australia
| | - Lejla Hagimola
- School
of Medical Sciences, Faculty of Medicine and Health, The University of Sydney, Sydney, New South Wales 2006, Australia
| | - Freda H. Passam
- School
of Medical Sciences, Faculty of Medicine and Health, The University of Sydney, Sydney, New South Wales 2006, Australia
| | - Denise P. Tran
- Sydney
Mass Spectrometry, The University of Sydney, Camperdown, New South Wales 2006, Australia
| | - Xiaoming Liu
- School
of Medical Sciences, Faculty of Medicine and Health, The University of Sydney, Sydney, New South Wales 2006, Australia
| | - Simone M. Schoenwaelder
- The
Heart Research Institute, The University
of Sydney, Newtown, New South Wales 2042, Australia
- School
of Medical Sciences, Faculty of Medicine and Health, The University of Sydney, Sydney, New South Wales 2006, Australia
| | - Shaun P. Jackson
- The
Heart Research Institute, The University
of Sydney, Newtown, New South Wales 2042, Australia
- Charles
Perkins Centre, The University of Sydney, Sydney, New South Wales 2006, Australia
| | - Richard J. Payne
- School
of Chemistry, Faculty of Science, The University
of Sydney, Sydney, New South Wales 2006, Australia
- Australian
Research Council Centre of Excellence for Innovations in Peptide and
Protein Science, The University of Sydney, Sydney, New South Wales 2006, Australia
| | - Xuyu Liu
- School
of Chemistry, Faculty of Science, The University
of Sydney, Sydney, New South Wales 2006, Australia
- The
Heart Research Institute, The University
of Sydney, Newtown, New South Wales 2042, Australia
| |
Collapse
|
2
|
Ellis ML, Terreaux A, Alwis I, Smythe R, Perdomo J, Eckly A, Cranmer SL, Passam FH, Maclean J, Schoenwaelder SM, Ruggeri ZM, Lanza F, Taoudi S, Yuan Y, Jackson SP. GPIbα-filamin A interaction regulates megakaryocyte localization and budding during platelet biogenesis. Blood 2024; 143:342-356. [PMID: 37922495 DOI: 10.1182/blood.2023021292] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2023] [Revised: 09/27/2023] [Accepted: 10/24/2023] [Indexed: 11/05/2023] Open
Abstract
ABSTRACT Glycoprotein Ibα (GPIbα) is expressed on the surface of platelets and megakaryocytes (MKs) and anchored to the membrane skeleton by filamin A (flnA). Although GPIb and flnA have fundamental roles in platelet biogenesis, the nature of this interaction in megakaryocyte biology remains ill-defined. We generated a mouse model expressing either human wild-type (WT) GPIbα (hGPIbαWT) or a flnA-binding mutant (hGPIbαFW) and lacking endogenous mouse GPIbα. Mice expressing the mutant GPIbα transgene exhibited macrothrombocytopenia with preserved GPIb surface expression. Platelet clearance was normal and differentiation of MKs to proplatelets was unimpaired in hGPIbαFW mice. The most striking abnormalities in hGPIbαFW MKs were the defective formation of the demarcation membrane system (DMS) and the redistribution of flnA from the cytoplasm to the peripheral margin of MKs. These abnormalities led to disorganized internal MK membranes and the generation of enlarged megakaryocyte membrane buds. The defective flnA-GPIbα interaction also resulted in misdirected release of buds away from the vasculature into bone marrow interstitium. Restoring the linkage between flnA and GPIbα corrected the flnA redistribution within MKs and DMS ultrastructural defects as well as restored normal bud size and release into sinusoids. These studies define a new mechanism of macrothrombocytopenia resulting from dysregulated MK budding. The link between flnA and GPIbα is not essential for the MK budding process, however, it plays a major role in regulating the structure of the DMS, bud morphogenesis, and the localized release of buds into the circulation.
Collapse
Affiliation(s)
- Marc L Ellis
- Thrombosis Research Group, The Heart Institute, Newtown, NSW, Australia
- Charles Perkins Centre, The University of Sydney, Camperdown, NSW, Australia
| | - Antoine Terreaux
- Blood Cell Formation Lab, Walter and Eliza Hall Institute, Parkville, VIC, Australia
| | - Imala Alwis
- Thrombosis Research Group, The Heart Institute, Newtown, NSW, Australia
- Charles Perkins Centre, The University of Sydney, Camperdown, NSW, Australia
| | - Rhyll Smythe
- Thrombosis Research Group, The Heart Institute, Newtown, NSW, Australia
- Charles Perkins Centre, The University of Sydney, Camperdown, NSW, Australia
| | - Jose Perdomo
- Haematology Research Unit, St George and Sutherland Clinical School, Faculty of Medicine, University of New South Wales, Sydney, NSW, Australia
| | - Anita Eckly
- Université de Strasbourg, INSERM, French Blood Establishment (EFS) Grand Est, BPPS UMR-S 1255, FMTS, Strasbourg, France
| | - Susan L Cranmer
- Eastern Health Clinical School, Monash University, Box Hill, VIC, Australia
| | - Freda H Passam
- Thrombosis Research Group, The Heart Institute, Newtown, NSW, Australia
- Charles Perkins Centre, The University of Sydney, Camperdown, NSW, Australia
| | - Jessica Maclean
- Thrombosis Research Group, The Heart Institute, Newtown, NSW, Australia
- Charles Perkins Centre, The University of Sydney, Camperdown, NSW, Australia
| | - Simone M Schoenwaelder
- Thrombosis Research Group, The Heart Institute, Newtown, NSW, Australia
- Charles Perkins Centre, The University of Sydney, Camperdown, NSW, Australia
- School of Medical Sciences, University of Sydney, Camperdown, NSW, Australia
| | - Zaverio M Ruggeri
- Department of Molecular Medicine, MERU-Roon Research Center on Vascular Biology, The Scripps Research Institute, La Jolla, CA
| | - Francois Lanza
- Université de Strasbourg, INSERM, French Blood Establishment (EFS) Grand Est, BPPS UMR-S 1255, FMTS, Strasbourg, France
| | - Samir Taoudi
- Blood Cell Formation Lab, Walter and Eliza Hall Institute, Parkville, VIC, Australia
- The University of Melbourne, Parkville, VIC, Australia
| | - Yuping Yuan
- Thrombosis Research Group, The Heart Institute, Newtown, NSW, Australia
- Charles Perkins Centre, The University of Sydney, Camperdown, NSW, Australia
| | - Shaun P Jackson
- Thrombosis Research Group, The Heart Institute, Newtown, NSW, Australia
- Charles Perkins Centre, The University of Sydney, Camperdown, NSW, Australia
- Department of Molecular Medicine, MERU-Roon Research Center on Vascular Biology, The Scripps Research Institute, La Jolla, CA
| |
Collapse
|
3
|
Hosseini E, Solouki A, Haghshenas M, Ghasemzadeh M, Schoenwaelder SM. Correction to: agitation-dependent biomechanical forces modulate GPVI receptor expression and platelet adhesion capacity during storage. Thromb J 2022; 20:16. [PMID: 35387657 PMCID: PMC8985334 DOI: 10.1186/s12959-022-00371-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
Affiliation(s)
- Ehteramolsadat Hosseini
- Blood Transfusion Research Centre, High Institute for Research and Education in Transfusion Medicine, Tehran, Iran
| | - Amin Solouki
- Blood Transfusion Research Centre, High Institute for Research and Education in Transfusion Medicine, Tehran, Iran
| | - Masood Haghshenas
- Blood Transfusion Research Centre, High Institute for Research and Education in Transfusion Medicine, Tehran, Iran
| | - Mehran Ghasemzadeh
- Blood Transfusion Research Centre, High Institute for Research and Education in Transfusion Medicine, Tehran, Iran.
| | - Simone M Schoenwaelder
- Charles Perkins Centre, The University of Sydney, Camperdown, NSW, Australia.,Heart Research Institute, Newtown, NSW, Australia
| |
Collapse
|
4
|
Hosseini E, Solouki A, Haghshenas M, Ghasemzadeh M, Schoenwaelder SM. Agitation-dependent biomechanical forces modulate GPVI receptor expression and platelet adhesion capacity during storage. Thromb J 2022; 20:3. [PMID: 35022046 PMCID: PMC8756730 DOI: 10.1186/s12959-021-00359-7] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2021] [Accepted: 12/09/2021] [Indexed: 02/02/2023] Open
Abstract
BACKGROUND Continuous agitation during storage slows down the platelet storage lesions. However, in special circumstances, manual-mixing can be alternatively used to store products for short time periods without compromising platelet quality. Based on this finding, and given the role of shear stress in modulating receptor expression, we were interested in comparing the levels of platelet adhesion receptor, GPVI and platelet adhesion capacity under each storage condition. METHODS Platelet concentrates (PCs) were divided into three groups: continuously-agitated PCs (CAG-PCs) with or without PP2 (Src kinase inhibitor) and manually-mixed PCs (MM-PCs). Platelet count/MPV, swirling, GPVI and P-selectin expression, GPVI shedding, platelet adhesion/spreading to collagen were examined during 5 days of storage. RESULTS While MM- and CAG-PCs showed similar levels of P-selectin expression, GPVI expression was significantly elevated in MM-PCs with lower GPVI shedding/expression ratios, enhanced platelet adhesion/spreading and swirling in manually-mixed PCs. Of note, CAG-PCs treated with PP2 also demonstrated lower P-selectin expression and GPVI shedding, higher GPVI expression and attenuated swirling and spreading capability. CONCLUSION Given the comparable platelet activation state in MM and CAG-PCs as indicated by P-selectin expression, enhanced platelet adhesion/spreading in MM-PCs, along with relatively higher GPVI expression here, supports previous studies demonstrating a role for biomechanical forces in modulating GPVI-dependent function. Thus, lower GPVI expression in CAG-PCs may be due to shear forces induced by agitation, which keeps this receptor down-regulated while also attenuating platelet adhesion/spreading capacities during storage. Low platelet function in PP2-CAG-PCs also highlights the importance of Src-kinases threshold activity in maintaining platelets quality.
Collapse
Affiliation(s)
- Ehteramolsadat Hosseini
- Blood Transfusion Research Centre, High Institute for Research and Education in Transfusion Medicine, Tehran, Iran
| | - Amin Solouki
- Blood Transfusion Research Centre, High Institute for Research and Education in Transfusion Medicine, Tehran, Iran
| | - Masood Haghshenas
- Blood Transfusion Research Centre, High Institute for Research and Education in Transfusion Medicine, Tehran, Iran
| | - Mehran Ghasemzadeh
- Blood Transfusion Research Centre, High Institute for Research and Education in Transfusion Medicine, Tehran, Iran.
| | - Simone M Schoenwaelder
- Charles Perkins Centre, The University of Sydney, Camperdown, NSW, Australia.,Heart Research Institute, Newtown, NSW, Australia
| |
Collapse
|
5
|
Ju LA, Kossmann S, Zhao YC, Moldovan L, Zhang Y, De Zoysa Ramasundara S, Zhou F, Lu H, Alwis I, Schoenwaelder SM, Yuan Y, Jackson SP. Microfluidic post method for 3-dimensional modeling of platelet–leukocyte interactions. Analyst 2022; 147:1222-1235. [DOI: 10.1039/d2an00270a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
These studies demonstrate the versatility and relevance of a novel ‘platelet post’ model to examine the adhesive interactions between platelets and neutrophils under 3D disturbed flow conditions relevant to thromboinflammation.
Collapse
Affiliation(s)
- Lining Arnold Ju
- Heart Research Institute, Newtown, NSW, 2042, Australia
- School of Biomedical Engineering, Faculty of Engineering, The University of Sydney, Darlington, NSW, 2008, Australia
- Charles Perkins Centre, The University of Sydney, Camperdown, NSW, 2006, Australia
| | - Sabine Kossmann
- Heart Research Institute, Newtown, NSW, 2042, Australia
- Charles Perkins Centre, The University of Sydney, Camperdown, NSW, 2006, Australia
| | - Yunduo Charles Zhao
- School of Biomedical Engineering, Faculty of Engineering, The University of Sydney, Darlington, NSW, 2008, Australia
| | - Laura Moldovan
- Heart Research Institute, Newtown, NSW, 2042, Australia
- Charles Perkins Centre, The University of Sydney, Camperdown, NSW, 2006, Australia
| | - Yingqi Zhang
- School of Biomedical Engineering, Faculty of Engineering, The University of Sydney, Darlington, NSW, 2008, Australia
| | - Savindi De Zoysa Ramasundara
- Heart Research Institute, Newtown, NSW, 2042, Australia
- School of Biomedical Engineering, Faculty of Engineering, The University of Sydney, Darlington, NSW, 2008, Australia
- Charles Perkins Centre, The University of Sydney, Camperdown, NSW, 2006, Australia
| | - Fangyuan Zhou
- Coulter Department of Biomedical Engineering, Georgia Institute of Technology, Atlanta, Georgia 30332, USA
- School of Chemical & Biomolecular Engineering, Georgia Institute of Technology, Atlanta, Georgia 30332, USA
- Petit Institute for Bioengineering and Biosciences, Georgia Institute of Technology, Atlanta, Georgia 30332, USA
| | - Hang Lu
- School of Chemical & Biomolecular Engineering, Georgia Institute of Technology, Atlanta, Georgia 30332, USA
- Petit Institute for Bioengineering and Biosciences, Georgia Institute of Technology, Atlanta, Georgia 30332, USA
| | - Imala Alwis
- Heart Research Institute, Newtown, NSW, 2042, Australia
- Charles Perkins Centre, The University of Sydney, Camperdown, NSW, 2006, Australia
| | - Simone M. Schoenwaelder
- Heart Research Institute, Newtown, NSW, 2042, Australia
- Charles Perkins Centre, The University of Sydney, Camperdown, NSW, 2006, Australia
| | - Yuping Yuan
- Heart Research Institute, Newtown, NSW, 2042, Australia
- Charles Perkins Centre, The University of Sydney, Camperdown, NSW, 2006, Australia
| | - Shaun P. Jackson
- Heart Research Institute, Newtown, NSW, 2042, Australia
- Charles Perkins Centre, The University of Sydney, Camperdown, NSW, 2006, Australia
- Department of Molecular Medicine, MERU-Roon Research Center on Vascular Biology, Scripps Research, La Jolla, California 92037, USA
| |
Collapse
|
6
|
Ju L, McFadyen JD, Al-Daher S, Alwis I, Chen Y, Tønnesen LL, Maiocchi S, Coulter B, Calkin AC, Felner EI, Cohen N, Yuan Y, Schoenwaelder SM, Cooper ME, Zhu C, Jackson SP. Compression force sensing regulates integrin α IIbβ 3 adhesive function on diabetic platelets. Nat Commun 2018; 9:1087. [PMID: 29540687 PMCID: PMC5852038 DOI: 10.1038/s41467-018-03430-6] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2017] [Accepted: 02/09/2018] [Indexed: 01/25/2023] Open
Abstract
Diabetes is associated with an exaggerated platelet thrombotic response at sites of vascular injury. Biomechanical forces regulate platelet activation, although the impact of diabetes on this process remains ill-defined. Using a biomembrane force probe (BFP), we demonstrate that compressive force activates integrin αIIbβ3 on discoid diabetic platelets, increasing its association rate with immobilized fibrinogen. This compressive force-induced integrin activation is calcium and PI 3-kinase dependent, resulting in enhanced integrin affinity maturation and exaggerated shear-dependent platelet adhesion. Analysis of discoid platelet aggregation in the mesenteric circulation of mice confirmed that diabetes leads to a marked enhancement in the formation and stability of discoid platelet aggregates, via a mechanism that is not inhibited by therapeutic doses of aspirin and clopidogrel, but is eliminated by PI 3-kinase inhibition. These studies demonstrate the existence of a compression force sensing mechanism linked to αIIbβ3 adhesive function that leads to a distinct prothrombotic phenotype in diabetes.
Collapse
Affiliation(s)
- Lining Ju
- Heart Research Institute, Thrombosis Group, Newtown, New South Wales, 2042, Australia
- Charles Perkins Centre, Level 3E Cardiovascular Division, The University of Sydney, New South Wales, 2006, Australia
- Australian Centre for Blood Diseases, Central Clinical School, Monash University, Melbourne, Victoria, 3004, Australia
| | - James D McFadyen
- Australian Centre for Blood Diseases, Central Clinical School, Monash University, Melbourne, Victoria, 3004, Australia
| | - Saheb Al-Daher
- Australian Centre for Blood Diseases, Central Clinical School, Monash University, Melbourne, Victoria, 3004, Australia
| | - Imala Alwis
- Heart Research Institute, Thrombosis Group, Newtown, New South Wales, 2042, Australia
- Charles Perkins Centre, Level 3E Cardiovascular Division, The University of Sydney, New South Wales, 2006, Australia
- Australian Centre for Blood Diseases, Central Clinical School, Monash University, Melbourne, Victoria, 3004, Australia
| | - Yunfeng Chen
- Heart Research Institute, Thrombosis Group, Newtown, New South Wales, 2042, Australia
- Coulter Department of Biomedical Engineering; and Woodruff School of Mechanical Engineering, Georgia Institute of Technology, Atlanta, GA, 30332, USA
- Parker H. Petit Institute for Bioengineering and Bioscience, Georgia Institute of Technology, Atlanta, GA, 30332, USA
- Department of Molecular and Experimental Medicine, The Scripps Research Institute, La Jolla, 92037, CA, USA
| | - Lotte L Tønnesen
- Heart Research Institute, Thrombosis Group, Newtown, New South Wales, 2042, Australia
- Charles Perkins Centre, Level 3E Cardiovascular Division, The University of Sydney, New South Wales, 2006, Australia
- Australian Centre for Blood Diseases, Central Clinical School, Monash University, Melbourne, Victoria, 3004, Australia
| | - Sophie Maiocchi
- Heart Research Institute, Thrombosis Group, Newtown, New South Wales, 2042, Australia
- Charles Perkins Centre, Level 3E Cardiovascular Division, The University of Sydney, New South Wales, 2006, Australia
| | - Brianna Coulter
- Heart Research Institute, Thrombosis Group, Newtown, New South Wales, 2042, Australia
- Charles Perkins Centre, Level 3E Cardiovascular Division, The University of Sydney, New South Wales, 2006, Australia
| | - Anna C Calkin
- Australian Centre for Blood Diseases, Central Clinical School, Monash University, Melbourne, Victoria, 3004, Australia
- Lipid Metabolism and Cardiometabolic Disease Laboratory, Baker Heart and Diabetes Institute, Melbourne, Victoria, 3004, Australia
| | - Eric I Felner
- Division of Pediatric Endocrinology, Emory University School of Medicine, Atlanta, GA, 30322, USA
| | - Neale Cohen
- Clinical Diabetes, Baker Heart and Diabetes Institute, Melbourne, Victoria, 3004, Australia
| | - Yuping Yuan
- Heart Research Institute, Thrombosis Group, Newtown, New South Wales, 2042, Australia
- Charles Perkins Centre, Level 3E Cardiovascular Division, The University of Sydney, New South Wales, 2006, Australia
- Australian Centre for Blood Diseases, Central Clinical School, Monash University, Melbourne, Victoria, 3004, Australia
| | - Simone M Schoenwaelder
- Heart Research Institute, Thrombosis Group, Newtown, New South Wales, 2042, Australia
- Charles Perkins Centre, Level 3E Cardiovascular Division, The University of Sydney, New South Wales, 2006, Australia
- Australian Centre for Blood Diseases, Central Clinical School, Monash University, Melbourne, Victoria, 3004, Australia
| | - Mark E Cooper
- Department of Diabetes, Central Clinical School, Monash University, Melbourne, 3004, Victoria, Australia
| | - Cheng Zhu
- Heart Research Institute, Thrombosis Group, Newtown, New South Wales, 2042, Australia.
- Coulter Department of Biomedical Engineering; and Woodruff School of Mechanical Engineering, Georgia Institute of Technology, Atlanta, GA, 30332, USA.
- Parker H. Petit Institute for Bioengineering and Bioscience, Georgia Institute of Technology, Atlanta, GA, 30332, USA.
| | - Shaun P Jackson
- Heart Research Institute, Thrombosis Group, Newtown, New South Wales, 2042, Australia.
- Charles Perkins Centre, Level 3E Cardiovascular Division, The University of Sydney, New South Wales, 2006, Australia.
- Australian Centre for Blood Diseases, Central Clinical School, Monash University, Melbourne, Victoria, 3004, Australia.
- Department of Molecular and Experimental Medicine, The Scripps Research Institute, La Jolla, 92037, CA, USA.
| |
Collapse
|
7
|
Schoenwaelder SM, Darbousset R, Cranmer SL, Ramshaw HS, Orive SL, Sturgeon S, Yuan Y, Yao Y, Krycer JR, Woodcock J, Maclean J, Pitson S, Zheng Z, Henstridge DC, van der Wal D, Gardiner EE, Berndt MC, Andrews RK, James DE, Lopez AF, Jackson SP. Correction: Corrigendum: 14-3-3ζ regulates the mitochondrial respiratory reserve linked to platelet phosphatidylserine exposure and procoagulant function. Nat Commun 2017; 8:16125. [PMID: 28853434 PMCID: PMC5582346 DOI: 10.1038/ncomms16125] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
|
8
|
Samson AL, Ho B, Au AE, Schoenwaelder SM, Smyth MJ, Bottomley SP, Kleifeld O, Medcalf RL. Physicochemical properties that control protein aggregation also determine whether a protein is retained or released from necrotic cells. Open Biol 2017; 6:rsob.160098. [PMID: 27810968 PMCID: PMC5133435 DOI: 10.1098/rsob.160098] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2016] [Accepted: 10/05/2016] [Indexed: 12/11/2022] Open
Abstract
Amyloidogenic protein aggregation impairs cell function and is a hallmark of many chronic degenerative disorders. Protein aggregation is also a major event during acute injury; however, unlike amyloidogenesis, the process of injury-induced protein aggregation remains largely undefined. To provide this insight, we profiled the insoluble proteome of several cell types after acute injury. These experiments show that the disulfide-driven process of nucleocytoplasmic coagulation (NCC) is the main form of injury-induced protein aggregation. NCC is mechanistically distinct from amyloidogenesis, but still broadly impairs cell function by promoting the aggregation of hundreds of abundant and essential intracellular proteins. A small proportion of the intracellular proteome resists NCC and is instead released from necrotic cells. Notably, the physicochemical properties of NCC-resistant proteins are contrary to those of NCC-sensitive proteins. These observations challenge the dogma that liberation of constituents during necrosis is anarchic. Rather, inherent physicochemical features including cysteine content, hydrophobicity and intrinsic disorder determine whether a protein is released from necrotic cells. Furthermore, as half of the identified NCC-resistant proteins are known autoantigens, we propose that physicochemical properties that control NCC also affect immune tolerance and other host responses important for the restoration of homeostasis after necrotic injury.
Collapse
Affiliation(s)
- Andre L Samson
- Australian Centre for Blood Diseases, Alfred Medical Research and Education Precinct (AMREP), Monash University, Melbourne, Victoria 3004, Australia .,Department of Biochemistry and Molecular Biology, Monash University, Clayton, Victoria 3800, Australia.,Heart Research Institute, and Charles Perkins Centre, University of Sydney, Camperdown, New South Wales 2006, Australia
| | - Bosco Ho
- Department of Biochemistry and Molecular Biology, Monash University, Clayton, Victoria 3800, Australia
| | - Amanda E Au
- Australian Centre for Blood Diseases, Alfred Medical Research and Education Precinct (AMREP), Monash University, Melbourne, Victoria 3004, Australia
| | - Simone M Schoenwaelder
- Australian Centre for Blood Diseases, Alfred Medical Research and Education Precinct (AMREP), Monash University, Melbourne, Victoria 3004, Australia.,Heart Research Institute, and Charles Perkins Centre, University of Sydney, Camperdown, New South Wales 2006, Australia
| | - Mark J Smyth
- Immunology in Cancer and Infection Laboratory, QIMR Berghofer Medical Research Institute, Herston, Queensland 4006, Australia.,School of Medicine, University of Queensland, Herston, Queensland 4006, Australia
| | - Stephen P Bottomley
- Department of Biochemistry and Molecular Biology, Monash University, Clayton, Victoria 3800, Australia
| | - Oded Kleifeld
- Department of Biochemistry and Molecular Biology, Monash University, Clayton, Victoria 3800, Australia.,Faculty of Biology, Technion-Israel Institute of Technology, Haifa 3200003, Israel
| | - Robert L Medcalf
- Australian Centre for Blood Diseases, Alfred Medical Research and Education Precinct (AMREP), Monash University, Melbourne, Victoria 3004, Australia
| |
Collapse
|
9
|
Yuan Y, Alwis I, Wu MCL, Kaplan Z, Ashworth K, Bark D, Pham A, Mcfadyen J, Schoenwaelder SM, Josefsson EC, Kile BT, Jackson SP. Neutrophil macroaggregates promote widespread pulmonary thrombosis after gut ischemia. Sci Transl Med 2017; 9:eaam5861. [PMID: 28954929 DOI: 10.1126/scitranslmed.aam5861] [Citation(s) in RCA: 44] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2016] [Revised: 05/02/2017] [Accepted: 08/21/2017] [Indexed: 11/02/2022]
Abstract
Gut ischemia is common in critically ill patients, promoting thrombosis and inflammation in distant organs. The mechanisms linking hemodynamic changes in the gut to remote organ thrombosis remain ill-defined. We demonstrate that gut ischemia in the mouse induces a distinct pulmonary thrombotic disorder triggered by neutrophil macroaggregates. These neutrophil aggregates lead to widespread occlusion of pulmonary arteries, veins, and the microvasculature. A similar pulmonary neutrophil-rich thrombotic response occurred in humans with the acute respiratory distress syndrome. Intravital microscopy during gut ischemia-reperfusion injury revealed that rolling neutrophils extract large membrane fragments from remnant dying platelets in multiple organs. These platelet fragments bridge adjacent neutrophils to facilitate macroaggregation. Platelet-specific deletion of cyclophilin D, a mitochondrial regulator of cell necrosis, prevented neutrophil macroaggregation and pulmonary thrombosis. Our studies demonstrate the existence of a distinct pulmonary thrombotic disorder triggered by dying platelets and neutrophil macroaggregates. Therapeutic targeting of platelet death pathways may reduce pulmonary thrombosis in critically ill patients.
Collapse
Affiliation(s)
- Yuping Yuan
- Australian Centre for Blood Diseases, Alfred Medical and Research Education Precinct, Monash University, Melbourne, Victoria 3004, Australia
- Heart Research Institute, Newtown, New South Wales 2042, Australia
- Charles Perkins Centre, University of Sydney, New South Wales 2006, Australia
| | - Imala Alwis
- Australian Centre for Blood Diseases, Alfred Medical and Research Education Precinct, Monash University, Melbourne, Victoria 3004, Australia
- Heart Research Institute, Newtown, New South Wales 2042, Australia
- Charles Perkins Centre, University of Sydney, New South Wales 2006, Australia
| | - Mike C L Wu
- Australian Centre for Blood Diseases, Alfred Medical and Research Education Precinct, Monash University, Melbourne, Victoria 3004, Australia
- Heart Research Institute, Newtown, New South Wales 2042, Australia
- Charles Perkins Centre, University of Sydney, New South Wales 2006, Australia
| | - Zane Kaplan
- Australian Centre for Blood Diseases, Alfred Medical and Research Education Precinct, Monash University, Melbourne, Victoria 3004, Australia
| | - Katrina Ashworth
- Australian Centre for Blood Diseases, Alfred Medical and Research Education Precinct, Monash University, Melbourne, Victoria 3004, Australia
| | - David Bark
- Australian Centre for Blood Diseases, Alfred Medical and Research Education Precinct, Monash University, Melbourne, Victoria 3004, Australia
| | - Alan Pham
- Department of Anatomical Pathology, Alfred Hospital, Prahran, Victoria 3181, Australia
| | - James Mcfadyen
- Australian Centre for Blood Diseases, Alfred Medical and Research Education Precinct, Monash University, Melbourne, Victoria 3004, Australia
| | - Simone M Schoenwaelder
- Australian Centre for Blood Diseases, Alfred Medical and Research Education Precinct, Monash University, Melbourne, Victoria 3004, Australia
- Heart Research Institute, Newtown, New South Wales 2042, Australia
| | - Emma C Josefsson
- Walter and Eliza Hall Institute of Medical Research, Parkville, Victoria 3052, Australia
- Department of Medical Biology, University of Melbourne, Parkville, Victoria 3010, Australia
| | - Benjamin T Kile
- Walter and Eliza Hall Institute of Medical Research, Parkville, Victoria 3052, Australia
- Department of Medical Biology, University of Melbourne, Parkville, Victoria 3010, Australia
- Department of Anatomy and Developmental Biology, Monash Biomedicine Discovery Institute, Monash University, Clayton, Victoria 3168, Australia
| | - Shaun P Jackson
- Australian Centre for Blood Diseases, Alfred Medical and Research Education Precinct, Monash University, Melbourne, Victoria 3004, Australia.
- Heart Research Institute, Newtown, New South Wales 2042, Australia
- Charles Perkins Centre, University of Sydney, New South Wales 2006, Australia
- Department of Molecular and Experimental Medicine, The Scripps Research Institute, La Jolla, CA 92037, USA
| |
Collapse
|
10
|
Zheng Z, Pinson JA, Mountford SJ, Orive S, Schoenwaelder SM, Shackleford D, Powell A, Nelson EM, Hamilton JR, Jackson SP, Jennings IG, Thompson PE. Discovery and antiplatelet activity of a selective PI3Kβ inhibitor (MIPS-9922). Eur J Med Chem 2016; 122:339-351. [PMID: 27387421 DOI: 10.1016/j.ejmech.2016.06.010] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2016] [Revised: 06/06/2016] [Accepted: 06/08/2016] [Indexed: 01/08/2023]
Abstract
A series of amino-substituted triazines were developed and examined for PI3Kβ inhibition and anti-platelet function. Structural adaptations of a morpholine ring of the prototype pan-PI3K inhibitor ZSTK474 yielded PI3Kβ selective compounds, where the selectivity largely derives from an interaction with the non-conserved Asp862 residue, as shown by site directed mutagenesis. The most PI3Kβ selective inhibitor from the series was studied in detail through a series of in vitro and in vivo functional studies. MIPS-9922, 10 potently inhibited ADP-induced washed platelet aggregation. It also inhibited integrin αIIbβ3 activation and αIIbβ3 dependent platelet adhesion to immobilized vWF under high shear. It prevented arterial thrombus formation in the in vivo electrolytic mouse model of thrombosis without inducing prolonged bleeding or excess blood loss.
Collapse
Affiliation(s)
- Zhaohua Zheng
- Medicinal Chemistry, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, Victoria 3052, Australia; Australian Centre for Blood Diseases, Monash University, Alfred Medical Research and Education Precinct (AMREP), 89 Commercial Road, Prahran, Victoria 3004, Australia
| | - Jo-Anne Pinson
- Medicinal Chemistry, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, Victoria 3052, Australia
| | - Simon J Mountford
- Medicinal Chemistry, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, Victoria 3052, Australia
| | - Stephanie Orive
- Australian Centre for Blood Diseases, Monash University, Alfred Medical Research and Education Precinct (AMREP), 89 Commercial Road, Prahran, Victoria 3004, Australia
| | - Simone M Schoenwaelder
- Australian Centre for Blood Diseases, Monash University, Alfred Medical Research and Education Precinct (AMREP), 89 Commercial Road, Prahran, Victoria 3004, Australia
| | - David Shackleford
- Centre for Drug Candidate Optimisation, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, Victoria 3052, Australia
| | - Andrew Powell
- Centre for Drug Candidate Optimisation, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, Victoria 3052, Australia
| | - Erin M Nelson
- Australian Centre for Blood Diseases, Monash University, Alfred Medical Research and Education Precinct (AMREP), 89 Commercial Road, Prahran, Victoria 3004, Australia
| | - Justin R Hamilton
- Australian Centre for Blood Diseases, Monash University, Alfred Medical Research and Education Precinct (AMREP), 89 Commercial Road, Prahran, Victoria 3004, Australia
| | - Shaun P Jackson
- Australian Centre for Blood Diseases, Monash University, Alfred Medical Research and Education Precinct (AMREP), 89 Commercial Road, Prahran, Victoria 3004, Australia
| | - Ian G Jennings
- Medicinal Chemistry, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, Victoria 3052, Australia
| | - Philip E Thompson
- Medicinal Chemistry, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, Victoria 3052, Australia.
| |
Collapse
|
11
|
Kaplan ZS, Zarpellon A, Alwis I, Yuan Y, McFadyen J, Ghasemzadeh M, Schoenwaelder SM, Ruggeri ZM, Jackson SP. Thrombin-dependent intravascular leukocyte trafficking regulated by fibrin and the platelet receptors GPIb and PAR4. Nat Commun 2015. [PMID: 26204458 DOI: 10.1038/ncomms8835] [Citation(s) in RCA: 48] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Thrombin is a central regulator of leukocyte recruitment and inflammation at sites of vascular injury, a function thought to involve primarily endothelial PAR cleavage. Here we demonstrate the existence of a distinct leukocyte-trafficking mechanism regulated by components of the haemostatic system, including platelet PAR4, GPIbα and fibrin. Utilizing a mouse endothelial injury model we show that thrombin cleavage of platelet PAR4 promotes leukocyte recruitment to sites of vascular injury. This process is negatively regulated by GPIbα, as seen in mice with abrogated thrombin-platelet GPIbα binding (hGPIbα(D277N)). In addition, we demonstrate that fibrin limits leukocyte trafficking by forming a physical barrier to intravascular leukocyte migration. These studies demonstrate a distinct 'checkpoint' mechanism of leukocyte trafficking involving balanced thrombin interactions with PAR4, GPIbα and fibrin. Dysregulation of this checkpoint mechanism is likely to contribute to the development of thromboinflammatory disorders.
Collapse
Affiliation(s)
- Zane S Kaplan
- Australian Centre for Blood Diseases, Monash University, Melbourne, Victoria 3004, Australia
| | - Alessandro Zarpellon
- Department of Molecular and Experimental Medicine, The Scripps Research Institute, La Jolla, California 92037, USA
| | - Imala Alwis
- Australian Centre for Blood Diseases, Monash University, Melbourne, Victoria 3004, Australia.,Heart Research Institute &Charles Perkins Centre, The University of Sydney, Sydney, New South Wales 2006, Australia
| | - Yuping Yuan
- Australian Centre for Blood Diseases, Monash University, Melbourne, Victoria 3004, Australia
| | - James McFadyen
- Australian Centre for Blood Diseases, Monash University, Melbourne, Victoria 3004, Australia
| | - Mehran Ghasemzadeh
- Australian Centre for Blood Diseases, Monash University, Melbourne, Victoria 3004, Australia.,Blood Transfusion Research Center, High Institute for Research and Education in Transfusion Medicine, Tehran, Iran
| | - Simone M Schoenwaelder
- Australian Centre for Blood Diseases, Monash University, Melbourne, Victoria 3004, Australia.,Heart Research Institute &Charles Perkins Centre, The University of Sydney, Sydney, New South Wales 2006, Australia
| | - Zaverio M Ruggeri
- Department of Molecular and Experimental Medicine, The Scripps Research Institute, La Jolla, California 92037, USA
| | - Shaun P Jackson
- Australian Centre for Blood Diseases, Monash University, Melbourne, Victoria 3004, Australia.,Department of Molecular and Experimental Medicine, The Scripps Research Institute, La Jolla, California 92037, USA.,Heart Research Institute &Charles Perkins Centre, The University of Sydney, Sydney, New South Wales 2006, Australia
| |
Collapse
|
12
|
Mountford JK, Petitjean C, Putra HWK, McCafferty JA, Setiabakti NM, Lee H, Tønnesen LL, McFadyen JD, Schoenwaelder SM, Eckly A, Gachet C, Ellis S, Voss AK, Dickins RA, Hamilton JR, Jackson SP. The class II PI 3-kinase, PI3KC2α, links platelet internal membrane structure to shear-dependent adhesive function. Nat Commun 2015; 6:6535. [PMID: 25779105 DOI: 10.1038/ncomms7535] [Citation(s) in RCA: 57] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2014] [Accepted: 02/05/2015] [Indexed: 12/29/2022] Open
Abstract
PI3KC2α is a broadly expressed lipid kinase with critical functions during embryonic development but poorly defined roles in adult physiology. Here we utilize multiple mouse genetic models to uncover a role for PI3KC2α in regulating the internal membrane reserve structure of megakaryocytes (demarcation membrane system) and platelets (open canalicular system) that results in dysregulated platelet adhesion under haemodynamic shear stress. Structural alterations in the platelet internal membrane lead to enhanced membrane tether formation that is associated with accelerated, yet highly unstable, thrombus formation in vitro and in vivo. Notably, agonist-induced 3-phosphorylated phosphoinositide production and cellular activation are normal in PI3KC2α-deficient platelets. These findings demonstrate an important role for PI3KC2α in regulating shear-dependent platelet adhesion via regulation of membrane structure, rather than acute signalling. These studies provide a link between the open canalicular system and platelet adhesive function that has relevance to the primary haemostatic and prothrombotic function of platelets.
Collapse
Affiliation(s)
- Jessica K Mountford
- Australian Centre for Blood Diseases, Monash University, Level 6, 89 Commercial Road, Melbourne, Victoria 3004, Australia
| | - Claire Petitjean
- Australian Centre for Blood Diseases, Monash University, Level 6, 89 Commercial Road, Melbourne, Victoria 3004, Australia
| | - Harun W Kusuma Putra
- Australian Centre for Blood Diseases, Monash University, Level 6, 89 Commercial Road, Melbourne, Victoria 3004, Australia
| | - Jonathan A McCafferty
- Australian Centre for Blood Diseases, Monash University, Level 6, 89 Commercial Road, Melbourne, Victoria 3004, Australia
| | - Natasha M Setiabakti
- Australian Centre for Blood Diseases, Monash University, Level 6, 89 Commercial Road, Melbourne, Victoria 3004, Australia
| | - Hannah Lee
- Australian Centre for Blood Diseases, Monash University, Level 6, 89 Commercial Road, Melbourne, Victoria 3004, Australia
| | - Lotte L Tønnesen
- Australian Centre for Blood Diseases, Monash University, Level 6, 89 Commercial Road, Melbourne, Victoria 3004, Australia
| | - James D McFadyen
- Australian Centre for Blood Diseases, Monash University, Level 6, 89 Commercial Road, Melbourne, Victoria 3004, Australia
| | - Simone M Schoenwaelder
- 1] Australian Centre for Blood Diseases, Monash University, Level 6, 89 Commercial Road, Melbourne, Victoria 3004, Australia [2] The Heart Research Institute and Charles Perkins Centre, The University of Sydney, Newtown 2050, Australia
| | - Anita Eckly
- Unité mixte de recherche S949 Institut National de la Santé et de la Recherche Médicale, Université de Strasbourg, Etablissement Français du Sang-Alsace 67000, Strasbourg, France
| | - Christian Gachet
- Unité mixte de recherche S949 Institut National de la Santé et de la Recherche Médicale, Université de Strasbourg, Etablissement Français du Sang-Alsace 67000, Strasbourg, France
| | - Sarah Ellis
- Sir Peter MacCallum Department of Oncology, Peter MacCallum Cancer Centre and The University of Melbourne, Melbourne, Victoria 3052, Australia
| | - Anne K Voss
- 1] Walter and Eliza Hall Institute of Medical Research, Melbourne, Victoria 3052, Australia [2] Department of Medical Biology, University of Melbourne, Melbourne, Victoria 3052, Australia
| | - Ross A Dickins
- 1] Walter and Eliza Hall Institute of Medical Research, Melbourne, Victoria 3052, Australia [2] Department of Medical Biology, University of Melbourne, Melbourne, Victoria 3052, Australia
| | - Justin R Hamilton
- Australian Centre for Blood Diseases, Monash University, Level 6, 89 Commercial Road, Melbourne, Victoria 3004, Australia
| | - Shaun P Jackson
- 1] Australian Centre for Blood Diseases, Monash University, Level 6, 89 Commercial Road, Melbourne, Victoria 3004, Australia [2] The Heart Research Institute and Charles Perkins Centre, The University of Sydney, Newtown 2050, Australia [3] Department of Molecular and Experimental Medicine, The Scripps Research Institute, San Diego, CA 92037, USA
| |
Collapse
|
13
|
Hughan SC, Spring CM, Schoenwaelder SM, Sturgeon S, Alwis I, Yuan Y, McFadyen JD, Westein E, Goddard D, Ono A, Yamanashi Y, Nesbitt WS, Jackson SP. Dok-2 adaptor protein regulates the shear-dependent adhesive function of platelet integrin αIIbβ3 in mice. J Biol Chem 2014; 289:5051-60. [PMID: 24385425 DOI: 10.1074/jbc.m113.520148] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023] Open
Abstract
The Dok proteins are a family of adaptor molecules that have a well defined role in regulating cellular migration, immune responses, and tumor progression. Previous studies have demonstrated that Doks-1 to 3 are expressed in platelets and that Dok-2 is tyrosine-phosphorylated downstream of integrin αIIbβ3, raising the possibility that it participates in integrin αIIbβ3 outside-in signaling. We demonstrate that Dok-2 in platelets is primarily phosphorylated by Lyn kinase. Moreover, deficiency of Dok-2 leads to dysregulated integrin αIIbβ3-dependent cytosolic calcium flux and phosphatidylinositol(3,4)P2 accumulation. Although agonist-induced integrin αIIbβ3 affinity regulation was unaltered in Dok-2(-/-) platelets, Dok-2 deficiency was associated with a shear-dependent increase in integrin αIIbβ3 adhesive function, resulting in enhanced platelet-fibrinogen and platelet-platelet adhesive interactions under flow. This increase in adhesion was restricted to discoid platelets and involved the shear-dependent regulation of membrane tethers. Dok-2 deficiency was associated with an increased rate of platelet aggregate formation on thrombogenic surfaces, leading to accelerated thrombus growth in vivo. Overall, this study defines an important role for Dok-2 in regulating biomechanical adhesive function of discoid platelets. Moreover, they define a previously unrecognized prothrombotic mechanism that is not detected by conventional platelet function assays.
Collapse
Affiliation(s)
- Sascha C Hughan
- From the Australian Centre for Blood Diseases, Faculty of Medicine, Nursing, and Health Sciences, Monash University, Alfred Medical Research and Education Precinct, Commercial Road, Melbourne, Victoria 3004
| | | | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
14
|
|
15
|
Guerreiro AS, Fattet S, Kulesza DW, Atamer A, Elsing AN, Shalaby T, Jackson SP, Schoenwaelder SM, Grotzer MA, Delattre O, Arcaro A. A sensitized RNA interference screen identifies a novel role for the PI3K p110γ isoform in medulloblastoma cell proliferation and chemoresistance. Mol Cancer Res 2011; 9:925-35. [PMID: 21652733 DOI: 10.1158/1541-7786.mcr-10-0200] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Medulloblastoma is the most common malignant brain tumor in children and is associated with a poor outcome. We were interested in gaining further insight into the potential of targeting the human kinome as a novel approach to sensitize medulloblastoma to chemotherapeutic agents. A library of small interfering RNA (siRNA) was used to downregulate the known human protein and lipid kinases in medulloblastoma cell lines. The analysis of cell proliferation, in the presence or absence of a low dose of cisplatin after siRNA transfection, identified new protein and lipid kinases involved in medulloblastoma chemoresistance. PLK1 (polo-like kinase 1) was identified as a kinase involved in proliferation in medulloblastoma cell lines. Moreover, a set of 6 genes comprising ATR, LYK5, MPP2, PIK3CG, PIK4CA, and WNK4 were identified as contributing to both cell proliferation and resistance to cisplatin treatment in medulloblastoma cells. An analysis of the expression of the 6 target genes in primary medulloblastoma tumor samples and cell lines revealed overexpression of LYK5 and PIK3CG. The results of the siRNA screen were validated by target inhibition with specific pharmacological inhibitors. A pharmacological inhibitor of p110γ (encoded by PIK3CG) impaired cell proliferation in medulloblastoma cell lines and sensitized the cells to cisplatin treatment. Together, our data show that the p110γ phosphoinositide 3-kinase isoform is a novel target for combinatorial therapies in medulloblastoma.
Collapse
Affiliation(s)
- Ana S Guerreiro
- Department of Oncology, University Children's Hospital, Zurich, Switzerland
| | | | | | | | | | | | | | | | | | | | | |
Collapse
|
16
|
De Laurentiis A, Pardo OE, Palamidessi A, Jackson SP, Schoenwaelder SM, Reichmann E, Scita G, Arcaro A. The catalytic class I(A) PI3K isoforms play divergent roles in breast cancer cell migration. Cell Signal 2010; 23:529-41. [PMID: 21056654 DOI: 10.1016/j.cellsig.2010.10.021] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2010] [Accepted: 10/23/2010] [Indexed: 02/05/2023]
Abstract
Transforming growth factor-β (TGFβ) plays an important role in breast cancer metastasis. Here phosphoinositide 3-kinase (PI3K) signalling was found to play an essential role in the enhanced migration capability of fibroblastoid cells (FibRas) derived from normal mammary epithelial cells (EpH4) by transduction of oncogenic Ras (EpRas) and TGFβ1. While expression of the PI3K isoform p110δ was down-regulated in FibRas cells, there was an increase in the expression of p110α and p110β in the fibroblastoid cells. The PI3K isoform p110β was found to specifically contribute to cell migration in FibRas cells, while p110α contributed to the response in EpH4, EpRas and FibRas cells. Akt, a downstream targets of PI3K signalling, had an inhibitory role in the migration of transformed breast cancer cells, while Rac, Cdc42 and the ribosomal protein S6 kinase (S6K) were necessary for the response. Together our data reveal a novel specific function of the PI3K isoform p110β in the migration of cells transformed by oncogenic H-Ras and TGF-β1.
Collapse
Affiliation(s)
- Angela De Laurentiis
- Division of Clinical Chemistry and Biochemistry, University Children's Hospital Zurich, 8032 Zurich, Switzerland
| | | | | | | | | | | | | | | |
Collapse
|
17
|
Qiu MR, Jiang L, Matthaei KI, Schoenwaelder SM, Kuffner T, Mangin P, Joseph JE, Low J, Connor D, Valenzuela SM, Curmi PMG, Brown LJ, Mahaut-Smith M, Jackson SP, Breit SN. Generation and characterization of mice with null mutation of the chloride intracellular channel 1 gene. Genesis 2010; 48:127-36. [PMID: 20049953 DOI: 10.1002/dvg.20590] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
CLIC1 belongs to a family of highly conserved and widely expressed intracellular chloride ion channel proteins existing in both soluble and membrane integrated forms. To study the physiological and biological role of CLIC1 in vivo, we undertook conditional gene targeting to engineer Clic1 gene knock-out mice. This represents creation of the first gene knock-out of a vertebrate CLIC protein family member. We first generated a Clic1 Knock-in (Clic1(FN)) allele, followed by Clic1 knock-out (Clic1(-/-)) mice by crossing Clic1(FN) allele with TNAP-cre mice, resulting in germline gene deletion through Cre-mediated recombination. Mice heterozygous or homozygous for these alleles are viable and fertile and appear normal. However, Clic1(-) (/-) mice show a mild platelet dysfunction characterized by prolonged bleeding times and decreased platelet activation in response to adenosine diphosphate stimulation linked to P2Y(12) receptor signaling.
Collapse
Affiliation(s)
- Min Ru Qiu
- St. Vincent's Centre for Applied Medical Research, St. Vincent's Hospital and University of New South Wales, Sydney, New South Wales, Australia
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
18
|
Qiu MR, Jiang L, Matthaei KI, Schoenwaelder SM, Kuffner T, Mangin P, Joseph JE, Low J, Connor D, Valenzuela SM, Curmi PM, Brown LJ, Mahaut-Smith M, Jackson SP, Breit SN. Generation and characterization of mice with null mutation of the chloride intracellular channel 1 gene. Genesis 2010. [DOI: 10.1002/dvg.20616] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
|
19
|
Abstract
Hemopoietic cells express relatively high levels of the type I phosphoinositide (PI) 3-kinase isoforms, with p110δ and γ exhibiting specialized signaling functions in neutrophils, monocytes, mast cells, and lymphocytes. In platelets, p110β appears to be the dominant PI 3-kinase isoform regulating platelet activation, irrespective of the nature of the primary platelet activating stimulus. Based on findings with isoform-selective p110β pharmacological inhibitors and more recently with p110β-deficient platelets, p110β appears to primarily signal downstream of G(i)- and tyrosine kinase-coupled receptors. Functionally, inhibition of p110β kinase function leads to a marked defect in integrin α(IIb)β₃ adhesion and reduced platelet thrombus formation in vivo. This defect in platelet adhesive function is not associated with increased bleeding, suggesting that therapeutic targeting of p110β may represent a safe approach to reduce thrombotic complications in patients with cardiovascular disease.
Collapse
Affiliation(s)
- Shaun P Jackson
- Australian Centre for Blood Diseases, Alfred Medical Research and Education Precinct (AMREP), Monash University, Melbourne, VIC, 3004, Australia.
| | | |
Collapse
|
20
|
Calkin AC, Drew BG, Ono A, Duffy SJ, Gordon MV, Schoenwaelder SM, Sviridov D, Cooper ME, Kingwell BA, Jackson SP. Reconstituted High-Density Lipoprotein Attenuates Platelet Function in Individuals With Type 2 Diabetes Mellitus by Promoting Cholesterol Efflux. Circulation 2009; 120:2095-104. [PMID: 19901191 DOI: 10.1161/circulationaha.109.870709] [Citation(s) in RCA: 144] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
Background—
Individuals with diabetes mellitus have an increased risk of cardiovascular disease and exhibit platelet hyperreactivity, increasing their resistance to antithrombotic therapies such as aspirin and clopidogrel. Reconstituted high-density lipoprotein (rHDL) has short-term beneficial effects on atherosclerotic plaques, but whether it can effectively reduce the reactivity of diabetic platelets is not known.
Methods and Results—
Individuals with type 2 diabetes mellitus were infused with placebo or rHDL (CSL-111; 20 mg · kg
−1
· h
−1
) for 4 hours, resulting in an ≈1.4-fold increase in plasma HDL cholesterol levels. rHDL infusion was associated with a >50% reduction in the ex vivo platelet aggregation response to multiple agonists, an effect that persisted in washed platelets. In vitro studies in platelets from healthy individuals revealed that the inhibitory effects of rHDL on platelet function were time and dose dependent and resulted in a widespread attenuation of platelet function and a 50% reduction in thrombus formation under flow. These effects could be recapitulated, in part, by the isolated phospholipid component of rHDL, which enhanced efflux of cholesterol from platelets and reduced lipid raft assembly. In contrast, the apolipoprotein AI component of rHDL had minimal effect on platelet function, cholesterol efflux, or lipid raft assembly.
Conclusion—
These findings suggest that rHDL therapy is highly effective at inhibiting the heightened reactivity of diabetic platelets, partly through reducing the cholesterol content of platelet membranes. These properties, combined with the known short-term beneficial effects of rHDL on atherosclerotic lesions, suggest that rHDL infusions may be an effective approach to reduce atherothrombotic complications in diabetic individuals.
Clinical Trial Registration Information—
URL: http://www.clinicaltrials.gov. Unique identifier: NCT00395148.
Collapse
Affiliation(s)
- Anna C. Calkin
- From the Diabetes Complications Laboratory (A.C.C., M.V.G., M.E.C.), Metabolic and Vascular Physiology Laboratory (B.G.D., S.J.D., B.A.K.), and Lipoproteins and Atherosclerosis Laboratory (D.S.), Baker IDI Heart and Diabetes Institute, and Australian Centre for Blood Diseases, Monash University (A.C.C., A.O., S.M.S., S.P.J.), Melbourne, Australia
| | - Brian G. Drew
- From the Diabetes Complications Laboratory (A.C.C., M.V.G., M.E.C.), Metabolic and Vascular Physiology Laboratory (B.G.D., S.J.D., B.A.K.), and Lipoproteins and Atherosclerosis Laboratory (D.S.), Baker IDI Heart and Diabetes Institute, and Australian Centre for Blood Diseases, Monash University (A.C.C., A.O., S.M.S., S.P.J.), Melbourne, Australia
| | - Akiko Ono
- From the Diabetes Complications Laboratory (A.C.C., M.V.G., M.E.C.), Metabolic and Vascular Physiology Laboratory (B.G.D., S.J.D., B.A.K.), and Lipoproteins and Atherosclerosis Laboratory (D.S.), Baker IDI Heart and Diabetes Institute, and Australian Centre for Blood Diseases, Monash University (A.C.C., A.O., S.M.S., S.P.J.), Melbourne, Australia
| | - Stephen J. Duffy
- From the Diabetes Complications Laboratory (A.C.C., M.V.G., M.E.C.), Metabolic and Vascular Physiology Laboratory (B.G.D., S.J.D., B.A.K.), and Lipoproteins and Atherosclerosis Laboratory (D.S.), Baker IDI Heart and Diabetes Institute, and Australian Centre for Blood Diseases, Monash University (A.C.C., A.O., S.M.S., S.P.J.), Melbourne, Australia
| | - Michelle V. Gordon
- From the Diabetes Complications Laboratory (A.C.C., M.V.G., M.E.C.), Metabolic and Vascular Physiology Laboratory (B.G.D., S.J.D., B.A.K.), and Lipoproteins and Atherosclerosis Laboratory (D.S.), Baker IDI Heart and Diabetes Institute, and Australian Centre for Blood Diseases, Monash University (A.C.C., A.O., S.M.S., S.P.J.), Melbourne, Australia
| | - Simone M. Schoenwaelder
- From the Diabetes Complications Laboratory (A.C.C., M.V.G., M.E.C.), Metabolic and Vascular Physiology Laboratory (B.G.D., S.J.D., B.A.K.), and Lipoproteins and Atherosclerosis Laboratory (D.S.), Baker IDI Heart and Diabetes Institute, and Australian Centre for Blood Diseases, Monash University (A.C.C., A.O., S.M.S., S.P.J.), Melbourne, Australia
| | - Dmitri Sviridov
- From the Diabetes Complications Laboratory (A.C.C., M.V.G., M.E.C.), Metabolic and Vascular Physiology Laboratory (B.G.D., S.J.D., B.A.K.), and Lipoproteins and Atherosclerosis Laboratory (D.S.), Baker IDI Heart and Diabetes Institute, and Australian Centre for Blood Diseases, Monash University (A.C.C., A.O., S.M.S., S.P.J.), Melbourne, Australia
| | - Mark E. Cooper
- From the Diabetes Complications Laboratory (A.C.C., M.V.G., M.E.C.), Metabolic and Vascular Physiology Laboratory (B.G.D., S.J.D., B.A.K.), and Lipoproteins and Atherosclerosis Laboratory (D.S.), Baker IDI Heart and Diabetes Institute, and Australian Centre for Blood Diseases, Monash University (A.C.C., A.O., S.M.S., S.P.J.), Melbourne, Australia
| | - Bronwyn A. Kingwell
- From the Diabetes Complications Laboratory (A.C.C., M.V.G., M.E.C.), Metabolic and Vascular Physiology Laboratory (B.G.D., S.J.D., B.A.K.), and Lipoproteins and Atherosclerosis Laboratory (D.S.), Baker IDI Heart and Diabetes Institute, and Australian Centre for Blood Diseases, Monash University (A.C.C., A.O., S.M.S., S.P.J.), Melbourne, Australia
| | - Shaun P. Jackson
- From the Diabetes Complications Laboratory (A.C.C., M.V.G., M.E.C.), Metabolic and Vascular Physiology Laboratory (B.G.D., S.J.D., B.A.K.), and Lipoproteins and Atherosclerosis Laboratory (D.S.), Baker IDI Heart and Diabetes Institute, and Australian Centre for Blood Diseases, Monash University (A.C.C., A.O., S.M.S., S.P.J.), Melbourne, Australia
| |
Collapse
|
21
|
Schoenwaelder SM, Ono A, Nesbitt WS, Lim J, Jarman K, Jackson SP. Phosphoinositide 3-kinase p110 beta regulates integrin alpha IIb beta 3 avidity and the cellular transmission of contractile forces. J Biol Chem 2009; 285:2886-96. [PMID: 19940148 DOI: 10.1074/jbc.m109.029132] [Citation(s) in RCA: 67] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Phosphoinositide (PI) 3-kinase (PI3K) signaling processes play an important role in regulating the adhesive function of integrin alpha(IIb)beta(3), necessary for platelet spreading and sustained platelet aggregation. PI3K inhibitors are effective at reducing platelet aggregation and thrombus formation in vivo and as a consequence are currently being evaluated as novel antithrombotic agents. PI3K regulation of integrin alpha(IIb)beta(3) activation (affinity modulation) primarily occurs downstream of G(i)-coupled and tyrosine kinase-linked receptors linked to the activation of Rap1b, AKT, and phospholipase C. In the present study, we demonstrate an important role for PI3Ks in regulating the avidity (strength of adhesion) of high affinity integrin alpha(IIb)beta(3) bonds, necessary for the cellular transmission of contractile forces. Using knock-out mouse models and isoform-selective PI3K inhibitors, we demonstrate that the Type Ia p110 beta isoform plays a major role in regulating thrombin-stimulated fibrin clot retraction in vitro. Reduced clot retraction induced by PI3K inhibitors was not associated with defects in integrin alpha(IIb)beta(3) activation, actin polymerization, or actomyosin contractility but was associated with a defect in integrin alpha(IIb)beta(3) association with the contractile cytoskeleton. Analysis of integrin alpha(IIb)beta(3) adhesion contacts using total internal reflection fluorescence microscopy revealed an important role for PI3Ks in regulating the stability of high affinity integrin alpha(IIb)beta(3) bonds. These studies demonstrate an important role for PI3K p110 beta in regulating the avidity of high affinity integrin alpha(IIb)beta(3) receptors, necessary for the cellular transmission of contractile forces. These findings may provide new insight into the potential antithrombotic properties of PI3K p110 beta inhibitors.
Collapse
Affiliation(s)
- Simone M Schoenwaelder
- Australian Centre for Blood Diseases, Monash University, Alfred Medical Research and Education Precinct, 89 Commercial Road, Melbourne, Victoria 3004, Australia.
| | | | | | | | | | | |
Collapse
|
22
|
|
23
|
Heller R, Chang Q, Ehrlich G, Hsieh SN, Schoenwaelder SM, Kuhlencordt PJ, Preissner KT, Hirsch E, Wetzker R. Overlapping and distinct roles for PI3Kbeta and gamma isoforms in S1P-induced migration of human and mouse endothelial cells. Cardiovasc Res 2008; 80:96-105. [PMID: 18558630 DOI: 10.1093/cvr/cvn159] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/18/2023] Open
Abstract
AIMS Sphingosine-1-phosphate (S1P), a key regulator of vascular homeostasis and angiogenesis, promotes endothelial cell migration via stimulation of phosphoinositide 3-kinase (PI3K). The aim of this study was to identify the role of PI3Kbeta and gamma isoforms and their downstream effector pathways in mediating endothelial cell migration induced by S1P. METHODS AND RESULTS Experiments were performed in human umbilical vein endothelial cells (HUVEC) and murine lung endothelial cells (MLEC). A combination of specific inhibitors, RNA interference, and PI3Kgamma(-/-) mice were used to investigate the role of PI3Kbeta and gamma isoforms in endothelial cell migration. Both PI3Kbeta and gamma isoforms are required for full migration induced by S1P, with Rac1 being a major mediator downstream of both isoforms. In addition, PI3Kbeta but not PI3Kgamma mediates migration via Akt but independent of Rac1 and endothelial NO synthase (eNOS). Further, a S1P-mediated activation of extracellular signal-regulated kinases (Erk) 1/2 contributes to the chemotactic response independent of PI3Kbeta or PI3Kgamma. CONCLUSIONS Our data demonstrate that both PI3Kbeta and PI3Kgamma isoforms are required for S1P-induced endothelial cell migration through activation of Rac1. In addition, PI3Kbeta initiates an Akt-sensitive chemotactic response which is independent of Rac1 and eNOS. Thus, PI3Kbeta and PI3Kgamma have both overlapping and distinct roles in regulating endothelial cell migration, which may underlie S1P-triggered angiogenic differentiation.
Collapse
Affiliation(s)
- Regine Heller
- Center for Molecular Biomedicine, Institute of Molecular Cell Biology, Friedrich Schiller University, Jena, Am Leutragraben 3, 07743 Jena, Germany.
| | | | | | | | | | | | | | | | | |
Collapse
|
24
|
Straub A, Wendel HP, Dietz K, Schiebold D, Peter K, Schoenwaelder SM, Ziemer G. Selective inhibition of the platelet phosphoinositide 3-kinase p110beta as promising new strategy for platelet protection during extracorporeal circulation. Thromb Haemost 2008; 99:609-15. [PMID: 18327411 DOI: 10.1160/th07-07-0452] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
Extracorporeal circulation (ECC) is used in cardiac surgery for cardiopulmonary bypass as well as in ventricular assist devices and for extracorporeal membrane oxygenation. Blood contact with the artificial surface and shear stress of ECC activates platelets and leukocytes resulting in a coagulopathy and proinflammatory events. Blockers of the platelet glycoprotein (GP) IIb/IIIa (CD41/CD61) can protect platelet function during ECC, a phenomenon called "platelet anaesthesia", but may be involved in post-ECC bleeding. We hypothesized that the new selective phosphoinositide 3-kinase p110beta inhibitor TGX-221 that inhibits shear-induced platelet activation without prolonging the bleeding time in vivo may also protect platelet function during ECC. Heparinized blood of healthy volunteers (n = 6) was treated in vitro with either the GP IIb/IIIa blocker tirofiban, TGX-221 or as control and circulated in an ECC model. Before and after 30 minutes circulation CD41 expression on the ECC-tubing as measure for platelet-ECC binding and generation of the platelet activation marker beta-thromboglobulin were determined using ELISA. Platelet aggregation and platelet-granulocyte binding were analysed in flow cytometry. After log-transforming the data statistical evaluation was performed using multifactor ANOVA in combination with Tukey's HSD test (global alpha = 5%). Tirofiban and TGX-221 inhibited platelet-ECC interaction, platelet aggregation and platelet-granulocyte binding. Tirofiban also inhibited ECC-induced beta-thromboglobulin release. The observed inhibition of platelet-ECC interaction and platelet activation by tirofiban contributes to explain the mechanism of "platelet anaesthesia". TGX-221 represents a promising alternative to GP IIb/IIIa blockade and should be further investigated for use during ECC in vivo.
Collapse
Affiliation(s)
- Andreas Straub
- Dept. of Thoracic, Cardiac and Vascular Surgery, University of Tübingen, Germany.
| | | | | | | | | | | | | |
Collapse
|
25
|
van der Meijden PEJ, Schoenwaelder SM, Feijge MAH, Cosemans JMEM, Munnix ICA, Wetzker R, Heller R, Jackson SP, Heemskerk JWM. Dual P2Y12 receptor signaling in thrombin-stimulated platelets - involvement of phosphoinositide 3-kinase β but not γ isoform in Ca2+ mobilization and procoagulant activity. FEBS J 2007; 275:371-85. [DOI: 10.1111/j.1742-4658.2007.06207.x] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
|
26
|
Arcaro A, Doepfner KT, Boller D, Guerreiro AS, Shalaby T, Jackson SP, Schoenwaelder SM, Delattre O, Grotzer MA, Fischer B. Novel role for insulin as an autocrine growth factor for malignant brain tumour cells. Biochem J 2007; 406:57-66. [PMID: 17506723 PMCID: PMC1948991 DOI: 10.1042/bj20070309] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
AT/RTs (atypical teratoid/rhabdoid tumours) of the CNS (central nervous system) are childhood malignancies associated with poor survival rates due to resistance to conventional treatments such as chemotherapy. We characterized a panel of human AT/RT and MRT (malignant rhabdoid tumour) cell lines for expression of RTKs (receptor tyrosine kinases) and their involvement in tumour growth and survival. When compared with normal brain tissue, AT/RT cell lines overexpressed the IR (insulin receptor) and the IGFIR (insulin-like growth factor-I receptor). Moreover, insulin was secreted by AT/RT cells grown in serum-free medium. Insulin potently activated Akt (also called protein kinase B) in AT/RT cells, as compared with other growth factors, such as epidermal growth factor. Pharmacological inhibitors, neutralizing antibodies, or RNAi (RNA interference) targeting the IR impaired the growth of AT/RT cell lines and induced apoptosis. Inhibitors of the PI3K (phosphoinositide 3-kinase)/Akt pathway also impaired basal and insulin-stimulated AT/RT cell proliferation. Experiments using RNAi and isoform-specific pharmacological inhibitors established a key role for the class I(A) PI3K p110alpha isoform in AT/RT cell growth and insulin signalling. Taken together, our results reveal a novel role for autocrine signalling by insulin and the IR in growth and survival of malignant human CNS tumour cells via the PI3K/Akt pathway.
Collapse
Affiliation(s)
- Alexandre Arcaro
- Division of Clinical Chemistry and Biochemistry, University Children's Hospital Zurich, CH-8032 Zurich, Switzerland.
| | | | | | | | | | | | | | | | | | | |
Collapse
|
27
|
Schoenwaelder SM, Ono A, Sturgeon S, Chan SM, Mangin P, Maxwell MJ, Turnbull S, Mulchandani M, Anderson K, Kauffenstein G, Rewcastle GW, Kendall J, Gachet C, Salem HH, Jackson SP. Identification of a unique co-operative phosphoinositide 3-kinase signaling mechanism regulating integrin alpha IIb beta 3 adhesive function in platelets. J Biol Chem 2007; 282:28648-28658. [PMID: 17673465 DOI: 10.1074/jbc.m704358200] [Citation(s) in RCA: 74] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Phosphoinositide (PI) 3-kinases play an important role in regulating the adhesive function of a variety of cell types through affinity modulation of integrins. Two type I PI 3-kinase isoforms (p110 beta and p110 gamma) have been implicated in G(i)-dependent integrin alpha(IIb)beta(3) regulation in platelets, however, the mechanisms by which they coordinate their signaling function remains unknown. By employing isoform-selective PI 3-kinase inhibitors and knock-out mouse models we have identified a unique mechanism of PI 3-kinase signaling co-operativity in platelets. We demonstrate that p110 beta is primarily responsible for G(i)-dependent phosphatidylinositol 3,4-bisphosphate (PI(3,4)P(2)) production in ADP-stimulated platelets and is linked to the activation of Rap1b and AKT. In contrast, defective integrin alpha(IIb)beta(3) activation in p110 gamma(-/-) platelets was not associated with alterations in the levels of PI(3,4)P(2) or active Rap1b/AKT. Analysis of the effects of active site pharmacological inhibitors confirmed that p110 gamma principally regulated integrin alpha(IIb)beta(3) activation through a non-catalytic signaling mechanism. Inhibition of the kinase function of PI 3-kinases, combined with deletion of p110 gamma, led to a major reduction in integrin alpha(IIb)beta(3) activation, resulting in a profound defect in platelet aggregation, hemostatic plug formation, and arterial thrombosis. These studies demonstrate a kinase-independent signaling function for p110 gamma in platelets. Moreover, they demonstrate that the combined catalytic and non-catalytic signaling function of p110 beta and p110 gamma is critical for P2Y(12)/G(i)-dependent integrin alpha(IIb)beta(3) regulation. These findings have potentially important implications for the rationale design of novel antiplatelet therapies targeting PI 3-kinase signaling pathways.
Collapse
Affiliation(s)
- Simone M Schoenwaelder
- Australian Centre for Blood Diseases, Monash University, Alfred Medical Research and Education Precinct (AMREP), 89 Commercial Road, Melbourne, Victoria, Australia 3004
| | - Akiko Ono
- Australian Centre for Blood Diseases, Monash University, Alfred Medical Research and Education Precinct (AMREP), 89 Commercial Road, Melbourne, Victoria, Australia 3004
| | - Sharelle Sturgeon
- Australian Centre for Blood Diseases, Monash University, Alfred Medical Research and Education Precinct (AMREP), 89 Commercial Road, Melbourne, Victoria, Australia 3004
| | - Siew Mei Chan
- Australian Centre for Blood Diseases, Monash University, Alfred Medical Research and Education Precinct (AMREP), 89 Commercial Road, Melbourne, Victoria, Australia 3004
| | - Pierre Mangin
- Australian Centre for Blood Diseases, Monash University, Alfred Medical Research and Education Precinct (AMREP), 89 Commercial Road, Melbourne, Victoria, Australia 3004
| | - Mhairi J Maxwell
- Australian Centre for Blood Diseases, Monash University, Alfred Medical Research and Education Precinct (AMREP), 89 Commercial Road, Melbourne, Victoria, Australia 3004
| | - Shannon Turnbull
- Australian Centre for Blood Diseases, Monash University, Alfred Medical Research and Education Precinct (AMREP), 89 Commercial Road, Melbourne, Victoria, Australia 3004
| | - Megha Mulchandani
- Australian Centre for Blood Diseases, Monash University, Alfred Medical Research and Education Precinct (AMREP), 89 Commercial Road, Melbourne, Victoria, Australia 3004
| | - Karen Anderson
- Australian Centre for Blood Diseases, Monash University, Alfred Medical Research and Education Precinct (AMREP), 89 Commercial Road, Melbourne, Victoria, Australia 3004
| | - Gilles Kauffenstein
- Auckland Cancer Society Research Centre, Faculty of Medical and Health Sciences, University of Auckland, Auckland 1020, New Zealand
| | - Gordon W Rewcastle
- Auckland Cancer Society Research Centre, Faculty of Medical and Health Sciences, University of Auckland, Auckland 1020, New Zealand
| | - Jackie Kendall
- Auckland Cancer Society Research Centre, Faculty of Medical and Health Sciences, University of Auckland, Auckland 1020, New Zealand
| | | | - Hatem H Salem
- Australian Centre for Blood Diseases, Monash University, Alfred Medical Research and Education Precinct (AMREP), 89 Commercial Road, Melbourne, Victoria, Australia 3004
| | - Shaun P Jackson
- Australian Centre for Blood Diseases, Monash University, Alfred Medical Research and Education Precinct (AMREP), 89 Commercial Road, Melbourne, Victoria, Australia 3004.
| |
Collapse
|
28
|
McCormack MP, Hall MA, Schoenwaelder SM, Zhao Q, Ellis S, Prentice JA, Clarke AJ, Slater NJ, Salmon JM, Jackson SP, Jane SM, Curtis DJ. Scl regulates NF-E2 in megakaryocytes and is required for platelet production during stress thrombopoiesis. Blood Cells Mol Dis 2007. [DOI: 10.1016/j.bcmd.2006.10.092] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
|
29
|
McCormack MP, Hall MA, Schoenwaelder SM, Zhao Q, Ellis S, Prentice JA, Clarke AJ, Slater NJ, Salmon JM, Jackson SP, Jane SM, Curtis DJ. A critical role for the transcription factor Scl in platelet production during stress thrombopoiesis. Blood 2006; 108:2248-56. [PMID: 16763211 PMCID: PMC1895552 DOI: 10.1182/blood-2006-02-002188] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2006] [Accepted: 05/30/2006] [Indexed: 12/12/2022] Open
Abstract
The generation of platelets from megakaryocytes in the steady state is regulated by a variety of cytokines and transcription factors, including thrombopoietin (TPO), GATA-1, and NF-E2. Less is known about platelet production in the setting of stress thrombopoiesis, a pivotal event in the context of cytotoxic chemotherapy. Here we show in mice that the transcription factor Scl is critical for platelet production after chemotherapy and in thrombopoiesis induced by administration of TPO. Megakaryocytes from these mice showed appropriate increases in number and ploidy but failed to shed platelets. Ultrastructural examination of Scl-null megakaryocytes revealed a disorganized demarcation membrane and reduction in platelet granules. Quantitative real-time polymerase chain reaction showed that Scl-null platelets lacked NF-E2, and chromatin immunoprecipitation analysis demonstrated Scl binding to the NF-E2 promoter in the human megakaryoblastic-cell line Meg-01, along with its binding partners E47, Lmo2, and the cofactors Ldb1 and GATA-2. These findings suggest that Scl acts up-stream of NF-E2 expression to control megakaryocyte development and platelet release in settings of thrombopoietic stress.
Collapse
Affiliation(s)
- Matthew P McCormack
- Bone Marrow Research Laboratories, Royal Melbourne Hospital, Melbourne Health Research Directorate, c/o Royal Melbourne Hospital Post Office, Grattan St, Parkville VIC 3050 Australia
| | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
30
|
Abstract
Arterial thrombosis is the single most common cause of death and disability in industrialized societies and is the primary pathogenic mechanism underlying acute myocardial infarction and ischemic stroke. Platelets play a central role in this process, and as a consequence, a great deal of effort has gone into identifying the mechanisms regulating the adhesive function of platelets. Platelet adhesion is controlled by intracellular signaling pathways, with growing evidence for a major role for phosphoinositide 3-kinases (PI3Ks) in this process. Platelets express all type I PI3K isoforms, including p110alpha, p110beta, p110delta and p110gamma, with recent evidence suggesting important roles for p110gamma and p110beta in regulating distinct phases of the platelet activation process. Deficiency of p110 gamma or inhibition of p110beta produces a marked defect in arterial thrombosis without a corresponding increase in bleeding time, raising the possibility that inhibition of one or more PI3K isoforms may represent an effective antithrombotic approach.
Collapse
Affiliation(s)
- S F Jackson
- Australian Centre for Blood Diseases, Monash University, 6th Level Burnet Building, Alfred Medical Research and Education Precinct (AMREP), 89 Commercial Road, Melbourne, Victoria, 3004, Australia.
| | | |
Collapse
|
31
|
Mangin P, Yap CL, Nonne C, Sturgeon SA, Goncalves I, Yuan Y, Schoenwaelder SM, Wright CE, Lanza F, Jackson SP. Thrombin overcomes the thrombosis defect associated with platelet GPVI/FcRgamma deficiency. Blood 2006; 107:4346-53. [PMID: 16391010 DOI: 10.1182/blood-2005-10-4244] [Citation(s) in RCA: 114] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
Fibrillar collagens are among the most potent activators of platelets and play an important role in the initiation of thrombosis. The glycoprotein VI (GPVI)/FcRgamma-chain complex is a central collagen receptor and inhibitors of GPVI produce a major defect in arterial thrombogenesis. In this study we have examined arterial thrombus formation in mice lacking the GPVI/FcRgamma-chain complex (FcRgamma(-/-)). Using 3 distinct arterial thrombosis models involving deep vascular injury, we demonstrate that deficiency of GPVI/FcRgamma is not associated with a major defect in arterial thrombus formation. In contrast, with milder vascular injury deficiency of GPVI/FcRgamma was associated with a 30% reduction in thrombus growth. Analysis of FcRgamma(-/-) platelets in vitro, using thrombin-dependent and -independent thrombosis models, demonstrated a major role for thrombin in overcoming the thrombosis defect associated with GPVI/FcRgamma deficiency. Inhibition of thrombin in vivo produced a much greater defect in thrombus formation in mice lacking GPVI/FcRgamma compared with normal controls. Similarly, thrombin inhibition produced a marked prolongation in bleeding time in FcRgamma(-/-) mice relative to wild-type mice. Our studies define an important role for thrombin in overcoming the hemostatic and thrombotic defect associated with GPVI/FcRgamma deficiency. Moreover, they raise the interesting possibility that the full antithrombotic potential of GPVI receptor antagonists may only be realized through the concurrent administration of anticoagulant agents.
Collapse
Affiliation(s)
- Pierre Mangin
- Australian Centre for Blood Diseases, Monash University, Melbourne, Victoria 3004, Australia
| | | | | | | | | | | | | | | | | | | |
Collapse
|
32
|
Chrzanowska-Wodnicka M, Smyth SS, Schoenwaelder SM, Fischer TH, White GC. Rap1b is required for normal platelet function and hemostasis in mice. J Clin Invest 2005. [DOI: 10.1172/jci22973c1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
|
33
|
Chrzanowska-Wodnicka M, Smyth SS, Schoenwaelder SM, Fischer TH, White GC. Rap1b is required for normal platelet function and hemostasis in mice. J Clin Invest 2005; 115:680-7. [PMID: 15696195 PMCID: PMC546455 DOI: 10.1172/jci22973] [Citation(s) in RCA: 246] [Impact Index Per Article: 12.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2004] [Accepted: 12/14/2004] [Indexed: 11/17/2022] Open
Abstract
Rap1b, an abundant small GTPase in platelets, becomes rapidly activated upon stimulation with agonists. Though it has been implicated to act downstream from G protein-coupled receptors (GPCRs) and upstream of integrin alpha IIbbeta3, the precise role of Rap1b in platelet function has been elusive. Here we report the generation of a murine rap1b knockout and show that Rap1b deficiency results in a bleeding defect due to defective platelet function. Aggregation of Rap1b-null platelets is reduced in response to stimulation with both GPCR-linked and GPCR-independent agonists. Underlying the defective Rap1b-null platelet function is decreased activation of integrin alphaIIbbeta3 in response to stimulation with agonists and signaling downstream from the integrin alpha IIbbeta3. In vivo, Rap1b-null mice are protected from arterial thrombosis. These data provide genetic evidence that Rap1b is involved in a common pathway of integrin activation, is required for normal hemostasis in vivo, and may be a clinically relevant antithrombotic therapy target.
Collapse
Affiliation(s)
- Magdalena Chrzanowska-Wodnicka
- Department of Medicine and Carolina Cardiovascular Biology Center, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599, USA.
| | | | | | | | | |
Collapse
|
34
|
Jackson SP, Schoenwaelder SM, Goncalves I, Nesbitt WS, Yap CL, Wright CE, Kenche V, Anderson KE, Dopheide SM, Yuan Y, Sturgeon SA, Prabaharan H, Thompson PE, Smith GD, Shepherd PR, Daniele N, Kulkarni S, Abbott B, Saylik D, Jones C, Lu L, Giuliano S, Hughan SC, Angus JA, Robertson AD, Salem HH. PI 3-kinase p110beta: a new target for antithrombotic therapy. Nat Med 2005; 11:507-14. [PMID: 15834429 DOI: 10.1038/nm1232] [Citation(s) in RCA: 474] [Impact Index Per Article: 24.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2004] [Accepted: 03/09/2005] [Indexed: 12/20/2022]
Abstract
Platelet activation at sites of vascular injury is essential for the arrest of bleeding; however, excessive platelet accumulation at regions of atherosclerotic plaque rupture can result in the development of arterial thrombi, precipitating diseases such as acute myocardial infarction and ischemic stroke. Rheological disturbances (high shear stress) have an important role in promoting arterial thrombosis by enhancing the adhesive and signaling function of platelet integrin alpha(IIb)beta(3) (GPIIb-IIIa). In this study we have defined a key role for the Type Ia phosphoinositide 3-kinase (PI3K) p110beta isoform in regulating the formation and stability of integrin alpha(IIb)beta(3) adhesion bonds, necessary for shear activation of platelets. Isoform-selective PI3K p110beta inhibitors have been developed which prevent formation of stable integrin alpha(IIb)beta(3) adhesion contacts, leading to defective platelet thrombus formation. In vivo, these inhibitors eliminate occlusive thrombus formation but do not prolong bleeding time. These studies define PI3K p110beta as an important new target for antithrombotic therapy.
Collapse
Affiliation(s)
- Shaun P Jackson
- Australian Centre for Blood Diseases, Monash University, 6th Floor Burnet Building Alfred Medical Research and Education Precinct, Prahran, Victoria, Australia 3181.
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
35
|
Abstract
The central importance of platelets in the development of arterial thrombosis and cardiovascular disease is well established. No other single cell type is responsible for as much morbidity and mortality as the platelet and, as a consequence, it represents a major target for therapeutic intervention. The growing awareness of the importance of platelets is reflected in the increasing number of patients receiving antiplatelet therapy, a trend that is likely to continue in the future. There are, however, significant drawbacks with existing therapies, including issues related to limited efficacy and safety. The discovery of a 'magic bullet' that selectively targets pathological thrombus formation without undermining haemostasis remains elusive, although recent progress in unravelling the molecular events regulating thrombosis has provided promising new avenues to solve this long-standing problem.
Collapse
Affiliation(s)
- Shaun P Jackson
- The Australian Centre for Blood Diseases, Department of Medicine, Monash University, Arnold Street, Box Hill Hospital, Box Hill, Victoria 3128, Australia.
| | | |
Collapse
|
36
|
Goncalves I, Hughan SC, Schoenwaelder SM, Yap CL, Yuan Y, Jackson SP. Integrin alpha IIb beta 3-dependent calcium signals regulate platelet-fibrinogen interactions under flow. Involvement of phospholipase C gamma 2. J Biol Chem 2003; 278:34812-22. [PMID: 12832405 DOI: 10.1074/jbc.m306504200] [Citation(s) in RCA: 68] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Platelet adhesion to fibrinogen is important for platelet aggregation and thrombus growth. In this study we have examined the mechanisms regulating platelet adhesion on immobilized fibrinogen under static and shear conditions. We demonstrate that integrin alpha IIb beta 3 engagement of immobilized fibrinogen is sufficient to induce an oscillatory calcium response, necessary for lamellipodial formation and platelet spreading. Released ADP increases the proportion of platelets exhibiting a cytosolic calcium response but is not essential for calcium signaling or lamellipodial extension. Pretreating platelets with the Src kinase inhibitor PP2, the inositol 1,4,5-trisphosphate (IP3) receptor antagonist 2-aminoethoxydiphenyl borate (APB-2), or the phospholipase C (PLC) inhibitor U73122 abolished calcium signaling and platelet spreading, suggesting a major role for Src kinase-regulated PLC isoforms in these processes. Analysis of PLC gamma 2-/- mouse platelets revealed a major role for this isoform in regulating cytosolic calcium flux and platelet spreading on fibrinogen. Under flow conditions, platelets derived from PLC gamma 2-/- mice formed less stable adhesive interactions with fibrinogen, particularly in the presence of ADP antagonists. Our studies define an important role for PLC gamma 2 in integrin alpha IIb beta 3-dependent calcium flux, necessary for stable platelet adhesion and spreading on fibrinogen. Furthermore, they establish an important cooperative signaling role for PLC gamma 2 and ADP in regulating platelet adhesion efficiency on fibrinogen.
Collapse
Affiliation(s)
- Isaac Goncalves
- Australian Centre for Blood Diseases, Department of Medicine, Monash University, Box Hill Hospital, Victoria 3128, Australia
| | | | | | | | | | | |
Collapse
|
37
|
Schoenwaelder SM, Hughan SC, Boniface K, Fernando S, Holdsworth M, Thompson PE, Salem HH, Jackson SP. RhoA sustains integrin alpha IIbbeta 3 adhesion contacts under high shear. J Biol Chem 2002; 277:14738-46. [PMID: 11830597 DOI: 10.1074/jbc.m200661200] [Citation(s) in RCA: 52] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The small GTPase RhoA modulates the adhesive nature of many cell types; however, despite high levels of expression in platelets, there is currently limited evidence for an important role for this small GTPase in regulating platelet adhesion processes. In this study, we have examined the role of RhoA in regulating the adhesive function of the major platelet integrin, alpha(IIb)beta(3). Our studies demonstrate that activation of RhoA occurs as a general feature of platelet activation in response to soluble agonists (thrombin, ADP, collagen), immobilized matrices (von Willebrand factor (vWf), fibrinogen) and high shear stress. Blocking the ligand binding function of integrin alpha(IIb)beta(3), by pretreating platelets with c7E3 Fab, demonstrated the existence of integrin alpha(IIb)beta(3)-dependent and -independent mechanisms regulating RhoA activation. Inhibition of RhoA (C3 exoenzyme) or its downstream effector Rho kinase had no effect on integrin alpha(IIb)beta(3) activation induced by soluble agonists or adhesive substrates, however, both inhibitors reduced shear-dependent platelet adhesion on immobilized vWf and shear-induced platelet aggregation in suspension. Detailed analysis of the sequential adhesive steps required for stable platelet adhesion on a vWf matrix under shear conditions revealed that RhoA did not regulate platelet tethering to vWf or the initial formation of integrin alpha(IIb)beta(3) adhesion contacts but played a major role in sustaining stable platelet-matrix interactions. These studies define a critical role for RhoA in regulating the stability of integrin alpha(IIb)beta(3) adhesion contacts under conditions of high shear stress.
Collapse
Affiliation(s)
- Simone M Schoenwaelder
- Department of Medicine, Australian Centre for Blood Diseases, Monash University, Box Hill Hospital, Arnold St., Box Hill, Victoria 3128, Australia.
| | | | | | | | | | | | | | | |
Collapse
|
38
|
Lawrenson ID, Wimmer-Kleikamp SH, Lock P, Schoenwaelder SM, Down M, Boyd AW, Alewood PF, Lackmann M. Ephrin-A5 induces rounding, blebbing and de-adhesion of EphA3-expressing 293T and melanoma cells by CrkII and Rho-mediated signalling. J Cell Sci 2002; 115:1059-72. [PMID: 11870224 DOI: 10.1242/jcs.115.5.1059] [Citation(s) in RCA: 132] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
Eph receptor tyrosine kinases and ephrins regulate morphogenesis in the developing embryo where they effect adhesion and motility of interacting cells. Although scarcely expressed in adult tissues, Eph receptors and ephrins are overexpressed in a range of tumours. In malignant melanoma, increased Eph and ephrin expression levels correlate with metastatic progression. We have examined cellular and biochemical responses of EphA3-expressing melanoma cell lines and human epithelial kidney 293T cells to stimulation with polymeric ephrin-A5 in solution and with surfaces of defined ephrin-A5 densities. Within minutes, rapid reorganisation of the actin and myosin cytoskeleton occurs through activation of RhoA, leading to the retraction of cellular protrusions,membrane blebbing and detachment, but not apoptosis. These responses are inhibited by monomeric ephrin-A5, showing that receptor clustering is required for this EphA3 response. Furthermore, the adapter CrkII, which associates with tyrosine-phosphorylated EphA3 in vitro, is recruited in vivo to ephrin-A5-stimulated EphA3. Expression of an SH3-domain mutated CrkII ablates cell rounding, blebbing and detachment. Our results suggest that recruitment of CrkII and activation of Rho signalling are responsible for EphA3-mediated cell rounding, blebbing and de-adhesion, and that ephrin-A5-mediated receptor clustering and EphA3 tyrosine kinase activity are essential for this response.
Collapse
Affiliation(s)
- Isobel D Lawrenson
- Ludwig Institute for Cancer Research, PO Box 2008, Royal Melbourne Hospital, Victoria 3050, Australia
| | | | | | | | | | | | | | | |
Collapse
|
39
|
Abstract
Remodeling of filamentous actin into distinct arrangements is precisely controlled by members of the Rho family of small GTPases [1]. A well characterized member of this family is RhoA, whose activation results in reorganization of the cytoskeleton into thick actin stress fibers terminating in integrin-rich focal adhesions [2]. Regulation of RhoA is required to maintain adhesion in stationary cells, but is also critical for cell spreading and migration [3]. Despite its biological importance, the signaling events leading to RhoA activation are not fully understood. Several independent studies have implicated tyrosine phosphorylation as a critical event upstream of RhoA [4]. Consistent with this, our recent studies have demonstrated the existence of a protein tyrosine phosphatase (PTPase), sensitive to the dipeptide aldehyde calpeptin, acting upstream of RhoA [5]. Here we identify the SH2 (Src homology region 2)-containing PTPase Shp-2 as a calpeptin-sensitive PTPase, and show that calpeptin interferes with the catalytic activity of Shp-2 in vitro and with Shp-2 signaling in vivo. Finally, we show that perturbation of Shp-2 activity by a variety of genetic manipulations results in raised levels of active RhoA. Together, these studies identify Shp-2 as a PTPase acting upstream of RhoA to regulate its activity and contribute to the coordinated control of cell movement.
Collapse
Affiliation(s)
- S M Schoenwaelder
- Australian Center for Blood Diseases, Monash University Department of Medicine, 3128,., Melbourne, Australia.
| | | | | | | | | | | |
Collapse
|
40
|
Abstract
Efficient platelet adhesion and aggregation at sites of vascular injury requires the synergistic contribution of multiple adhesion receptors. The initial adhesion of platelets to subendothelial matrix proteins involves GPIb/V/IX and one or more platelet integrins, including integrin alpha IIb beta 3, alpha 2 beta 1, alpha 5 beta 1 and possibly alpha 6 beta 1. In contrast, platelet-platelet adhesion (platelet cohesion or aggregation) is mediated exclusively by GPIb/V/IX and integrin alpha IIb beta 3. Integrin alpha IIb beta 3 is a remarkable receptor that not only stabilizes platelet-vessel wall and platelet-platelet adhesion contacts, but also transduces signals necessary for a range of other functional responses. These signals are linked to cytoskeletal reorganization and platelet spreading, membrane vesiculation and fibrin clot formation, and tension development on a fibrin clot leading to clot retraction. This diverse functional role of integrin alpha IIb beta 3 is reflected by its ability to induce the activation of a broad range of signaling enzymes that are involved in membrane phospholipid metabolism, protein phosphorylation, calcium mobilization and activation of small GTPases. An important calcium-dependent signaling enzyme involved in integrin alpha IIb beta 3 outside-in signaling is the thiol protease, calpain. This enzyme proteolyses a number of key structural and signaling proteins involved in cytoskeletal remodeling and platelet activation. These proteolytic events appear to play a potentially important role in modulating the adhesive and signaling function of integrin alpha IIb beta 3.
Collapse
Affiliation(s)
- S M Schoenwaelder
- Australian Centre for Blood Diseases, Department of Medicine, Monash Medical School, Box Hill Hospital, Victoria, Australia
| | | | | |
Collapse
|
41
|
Schoenwaelder SM, Burridge K. Evidence for a calpeptin-sensitive protein-tyrosine phosphatase upstream of the small GTPase Rho. A novel role for the calpain inhibitor calpeptin in the inhibition of protein-tyrosine phosphatases. J Biol Chem 1999; 274:14359-67. [PMID: 10318859 DOI: 10.1074/jbc.274.20.14359] [Citation(s) in RCA: 86] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Activation of the thiol protease calpain results in proteolysis of focal adhesion-associated proteins and severing of cytoskeletal-integrin links. We employed a commonly used inhibitor of calpain, calpeptin, to examine a role for this protease in the reorganization of the cytoskeleton under a variety of conditions. Calpeptin induced stress fiber formation in both forskolin-treated REF-52 fibroblasts and serum-starved Swiss 3T3 fibroblasts. Surprisingly, calpeptin was the only calpain inhibitor of several tested with the ability to induce these effects, suggesting that calpeptin may act on targets besides calpain. Here we show that calpeptin inhibits tyrosine phosphatases, enhancing tyrosine phosphorylation particularly of paxillin. Calpeptin preferentially inhibits membrane-associated phosphatase activity. Consistent with this observation, in vitro phosphatase assays using purified glutathione S-transferase fusion proteins demonstrated a preference for the transmembrane protein-tyrosine phosphatase-alpha over the cytosolic protein-tyrosine phosphatase-1B. Furthermore, unlike wide spectrum inhibitors of tyrosine phosphatases such as pervanadate, calpeptin appeared to inhibit a subset of phosphatases. Calpeptin-induced assembly of stress fibers was inhibited by botulinum toxin C3, indicating that calpeptin is acting on a phosphatase upstream of the small GTPase Rho, a protein that controls stress fiber and focal adhesion assembly. Not only does this work reveal that calpeptin is an inhibitor of protein-tyrosine phosphatases, but it suggests that calpeptin will be a valuable tool to identify the phosphatase activity upstream of Rho.
Collapse
Affiliation(s)
- S M Schoenwaelder
- Department of Cell Biology and Anatomy, University of North Carolina, Chapel Hill, North Carolina 27599-7090, USA
| | | |
Collapse
|
42
|
Abstract
Clustering of integrins into focal adhesions and focal complexes is regulated by the actin cytoskeleton. In turn, actin dynamics are governed by Rho family GTPases. Integrin-mediated adhesion activates these GTPases, triggering assembly of filopodia, lamellipodia and stress fibers. In the past few years, signaling pathways have begun to be identified that promote focal adhesion disassembly and integrin dispersal. Many of these pathways result in decreased myosin-mediated cell contractility.
Collapse
Affiliation(s)
- S M Schoenwaelder
- The Department of Cell Biology and Anatomy, 108 Taylor Hall, CB#7090, University of North Carolina, Chapel Hill, NC 27599, USA.
| | | |
Collapse
|
43
|
Schoenwaelder SM, Kulkarni S, Salem HH, Imajoh-Ohmi S, Yamao-Harigaya W, Saido TC, Jackson SP. Distinct substrate specificities and functional roles for the 78- and 76-kDa forms of mu-calpain in human platelets. J Biol Chem 1997; 272:24876-84. [PMID: 9312088 DOI: 10.1074/jbc.272.40.24876] [Citation(s) in RCA: 50] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
The intracellular thiol protease mu-calpain exists as a heterodimeric proenzyme, consisting of a large 80-kDa catalytic subunit and a smaller 30-kDa regulatory subunit. Activation of mu-calpain requires calcium influx across the plasma membrane and the subsequent autoproteolytic conversion of the 80-kDa large subunit to a 78-kDa "intermediate" and a 76-kDa fully autolyzed form. Currently, there is limited information on the substrate specificities and functional roles of these distinct active forms of mu-calpain within the cell. Using antibodies that can distinguish among the 80-, 78-, and 76-kDa forms of mu-calpain, we have demonstrated a close correlation between the autolytic generation of the 78-kDa enzyme and the proteolysis of the non-receptor tyrosine phosphatase, PTP-1B, in ionophore A23187-stimulated platelets. Time course studies revealed that pp60(c-)src proteolysis lagged well behind that of PTP-1B and correlated closely with the generation of the fully proteolyzed form of mu-calpain (76 kDa). In vitro proteolysis experiments with purified mu-calpain and immunoprecipitated PTP-1B or pp60(c-)src confirmed selective proteolysis of pp60(c-)src by the 76-kDa enzyme, whereas PTP-1B cleavage was mediated by both the 76- and 78-kDa forms of mu-calpain. Studies using selective pharmacological inhibitors against the different autolytic forms of mu-calpain have demonstrated that the initial conversion of the mu-calpain large subunit to the 78-kDa form is responsible for the reduction in platelet-mediated clot retraction, whereas complete proteolytic activation of mu-calpain (76 kDa) is responsible for the shedding of procoagulant-rich membrane vesicles from the cell surface. These studies demonstrate the existence of multiple active forms of mu-calpain within the cell, that have unique substrate specificities and distinct functional roles.
Collapse
Affiliation(s)
- S M Schoenwaelder
- Department of Medicine, Monash Medical School, the Australian Centre for Blood Diseases, Victoria 3128, Australia
| | | | | | | | | | | | | |
Collapse
|
44
|
Schoenwaelder SM, Yuan Y, Cooray P, Salem HH, Jackson SP. Calpain cleavage of focal adhesion proteins regulates the cytoskeletal attachment of integrin alphaIIbbeta3 (platelet glycoprotein IIb/IIIa) and the cellular retraction of fibrin clots. J Biol Chem 1997; 272:1694-702. [PMID: 8999848 DOI: 10.1074/jbc.272.3.1694] [Citation(s) in RCA: 103] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023] Open
Abstract
The intracellular thiol protease calpain catalyzes the limited proteolysis of various focal adhesion structural proteins and signaling enzymes in adherent cells. In human platelets, calpain activation is dependent on fibrinogen binding to integrin alphaIIbbeta3 and subsequent platelet aggregation, suggesting a potential role for this protease in the regulation of postaggregation responses. In this study, we have examined the effects of calpain activation on several postaggregation events in human platelets, including the cytoskeletal attachment of integrin alphaIIbbeta3, the tyrosine phosphorylation of cytoskeletal proteins, and the cellular retraction of fibrin clots. We demonstrate that calpain activation in either washed platelets or platelet-rich plasma is associated with a marked reduction in platelet-mediated fibrin clot retraction. This relaxation of clot retraction was observed in both thrombin and ionophore A23187-stimulated platelets. Calcium dose-response studies (extracellular calcium concentrations between 0.1 microM and 1 M) revealed a strong correlation between calpain activation and relaxed clot retraction. Furthermore, pretreating platelets with the calpain inhibitors calpeptin and calpain inhibitor I prevented the calpain-mediated reduction in clot retraction. Relaxed fibrin clot retraction was associated with the cleavage of several platelet focal adhesion structural proteins and signaling enzymes, resulting in the dissociation of talin, pp60(c-)src, and integrin alphaIIbbeta3 from the contractile cytoskeleton and the tyrosine dephosphorylation of multiple cytoskeletal proteins. These studies suggest an important role for calpain in the regulation of multiple postaggregation events in human platelets. The ability of calpain to inhibit clot retraction is likely to be due to the cleavage of both structural and signaling proteins involved in modulating integrin-cytoskeletal interactions.
Collapse
Affiliation(s)
- S M Schoenwaelder
- Department of Medicine, Monash Medical School, Box Hill Hospital, Arnold Street, Box Hill, Victoria, Australia 3128
| | | | | | | | | |
Collapse
|
45
|
Jackson SP, Schoenwaelder SM, Yuan Y, Salem HH, Cooray P. Non-receptor protein tyrosine kinases and phosphatases in human platelets. Thromb Haemost 1996; 76:640-50. [PMID: 8950767] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
There is now a large and rapidly growing body of information on the different types of non-receptor tyrosine kinases and phosphatases present within platelets. These enzymes appear to play a critical role in co-ordinating, integrating and amplifying signals from multiple cell surface receptors. Despite considerable progress in this area of research over the last decade, a coherent understanding of how these enzymes fit into the complex communication networks of platelets remains elusive. The challenge ahead will be to define the molecular interactions and hierarchies between tyrosine kinases, phosphatases and other platelet signalling enzymes, and to pinpoint the key phosphorylation reactions required for the induction of specific platelet responses.
Collapse
Affiliation(s)
- S P Jackson
- Department of Medicine, Monash Medical School, Box Hill Hospital, Victoria, Australia
| | | | | | | | | |
Collapse
|
46
|
Yuan Y, Schoenwaelder SM, Salem HH, Jackson SP. The bioactive phospholipid, lysophosphatidylcholine, induces cellular effects via G-protein-dependent activation of adenylyl cyclase. J Biol Chem 1996; 271:27090-8. [PMID: 8900200 DOI: 10.1074/jbc.271.43.27090] [Citation(s) in RCA: 78] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023] Open
Abstract
The naturally occurring phospholipid, lysophosphatidylcholine (lyso-PC), regulates a broad range of cell processes, including gene transcription, mitogenesis, monocyte chemotaxis, smooth muscle relaxation, and platelet activation. Despite the growing list of cellular effects attributable to lyso-PC, the mechanism(s) by which it alters cell function have not been elucidated. In this report, we have examined the effects of exogenous lyso-PC on signal transduction processes within a variety of lyso-PC-responsive cells, including human platelets, monocyte-like THP-1 cells, and the megakaryoblastic cell line, MEG-01. Pretreatment of each of these cells with increasing concentrations of lyso-PC (25-150 microg/ml) was associated with a progressive increase in the cytosolic concentration of cAMP. The accumulation of cAMP in platelets correlated closely with the ability of lyso-PC to inhibit multiple platelet processes, including platelet aggregation, agonist-induced protein kinase C activation, thromboxane A2 generation, and the tyrosine phosphorylation of platelet proteins. In each of the cell types examined, the ability of lyso-PC to increase the cellular levels of cAMP was synergistically enhanced by pretreating the cells with the cAMP phosphodiesterase inhibitor, theophylline (5 mM), and was specifically inhibited by the P-site inhibitor of adenylyl cyclase, 2,5-dideoxyadenosine. A role for the stimulatory G-protein, Gs, in the lyso-PC-induced activation of adenylyl cyclase was suggested by the ability of the GTPase inhibitor, guanylyl 5'-thiophosphate (0.2 mM), to inhibit the lyso-PC-stimulated increase in cAMP, and also by the ability of cholera toxin to inhibit increases in membrane GTPase activity in response to lyso-PC. The functional significance of lyso-PC-induced activation of adenylyl cyclase was investigated in MEG-01 cells. Treatment of these cells with either lyso-PC or dibutyryl cAMP for 36-40 h resulted in a 3-5-fold increase in the surface expression of the natural anticoagulant protein, thrombomodulin (TM). The ability of lyso-PC to increase TM expression was abolished by pretreating these cells with the adenylyl cyclase inhibitor, 2,5-dideoxyadenosine, whereas the dibutyryl cAMP-induced increase in TM remained insensitive to adenylyl cyclase inhibition. These studies define an important role for the adenylyl cyclase signaling system in mediating cellular effects induced by lyso-PC.
Collapse
Affiliation(s)
- Y Yuan
- Department of Medicine, Monash Medical School, Box Hill Hospital, Victoria, Australia 3128
| | | | | | | |
Collapse
|
47
|
Cooray P, Yuan Y, Schoenwaelder SM, Mitchell CA, Salem HH, Jackson SP. Focal adhesion kinase (pp125FAK) cleavage and regulation by calpain. Biochem J 1996; 318 ( Pt 1):41-7. [PMID: 8761450 PMCID: PMC1217586 DOI: 10.1042/bj3180041] [Citation(s) in RCA: 138] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
Focal adhesion kinase (125 kDa form; pp125FAK) is a widely expressed non-receptor tyrosine kinase that is implicated in integrin-mediated signal transduction. We have identified a novel means of pp 125FAK regulation in human platelets, in which this kinase undergoes sequential proteolytic modification from the native 125 kDa form to 90, 45 and 40 kDa fragments in thrombin-, collagen- and ionophore A23187-stimulated platelets. The proteolysis of pp125FAK was prevented by pretreating platelets with the calpain inhibitors calpeptin or calpain inhibitor-1, and was reproduced in vitro by incubating immunoprecipitated pp125FAK with purified calpain. Proteolysis of pp125FAK resulted in a dramatic reduction in its autokinase activity and led to its dissociation from the cytoskeletal fraction of platelets. These studies define a novel signal-terminating role for calpain, wherein proteolytic modification of pp125FAK attenuates its autokinase activity and induces its subcellular relocation within the cell.
Collapse
Affiliation(s)
- P Cooray
- Department of Medicine, Monash Medical School, Victoria, Australia
| | | | | | | | | | | |
Collapse
|
48
|
Jackson SP, Schoenwaelder SM, Matzaris M, Brown S, Mitchell CA. Phosphatidylinositol 3,4,5-trisphosphate is a substrate for the 75 kDa inositol polyphosphate 5-phosphatase and a novel 5-phosphatase which forms a complex with the p85/p110 form of phosphoinositide 3-kinase. EMBO J 1995; 14:4490-500. [PMID: 7556092 PMCID: PMC394541 DOI: 10.1002/j.1460-2075.1995.tb00128.x] [Citation(s) in RCA: 59] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
Abstract
Agonist-stimulated production of phosphatidylinositol 3,4,5-trisphosphate [PtdIns(3,4,5)P3], is considered the primary output signal of activated phosphoinositide (PI) 3-kinase. The physiological targets of this novel phospholipid and the identity of enzymes involved in its metabolism have not yet been established. We report here the identification of two enzymes which hydrolyze the 5-position phosphate of PtdIns(3,4,5)P3, forming phosphatidylinositol (3,4)-bisphosphate. One of these enzymes is the 75 kDa inositol polyphosphate 5-phosphatase (75 kDa 5-phosphatase), which has previously been demonstrated to metabolize inositol 1,4,5-trisphosphate [Ins(1,4,5)P3], inositol 1,3,4,5-tetrakisphosphate [Ins(1,3,4,5)P4] and phosphatidylinositol 4,5-bisphosphate [PtdIns(4,5)P2]. We have identified a second PtdIns(3,4,5)P3 5-phosphatase in the cytosolic fraction of platelets, which forms a complex with the p85/p110 form of PI 3-kinase. This enzyme is immunologically and chromatographically distinct from the platelet 43 kDa and 75 kDa 5-phosphatases and is unique in that it removes the 5-position phosphate from PtdIns(3,4,5)P3, but does not metabolize PtdIns(4,5)P2, Ins(1,4,5)P3 or Ins(1,3,4,5)P4. These studies demonstrate the existence of multiple PtdIns(3,4,5)P3 5-phosphatases within the cell.
Collapse
Affiliation(s)
- S P Jackson
- Department of Medicine, Monash Medical School, Box Hill Hospital, Victoria, Australia
| | | | | | | | | |
Collapse
|
49
|
Schoenwaelder SM, Jackson SP, Yuan Y, Teasdale MS, Salem HH, Mitchell CA. Tyrosine kinases regulate the cytoskeletal attachment of integrin alpha IIb beta 3 (platelet glycoprotein IIb/IIIa) and the cellular retraction of fibrin polymers. J Biol Chem 1994; 269:32479-87. [PMID: 7798249] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023] Open
Abstract
Integrins promote cell-substratum and cell-cell adhesion by acting as transmembrane linker molecules between extracellular adhesion proteins and the actin-rich cytoskeleton. The integrin alpha IIb beta 3 (platelet glycoprotein IIb/IIIa) is essential for platelet spreading, aggregation, fibrin clot retraction, and for the transduction of extracellular signals. We examined the effect of the specific tyrosine kinase inhibitor herbimycin A on integrin and cytoskeletal-mediated events in thrombin-stimulated platelets. Incubation of washed platelets for 24 h with herbimycin A (5 microM) abolished the thrombin-stimulated cytoskeletal enzyme activity of pp60c-src in parallel with a reduction in the tyrosine phosphorylation of multiple platelet proteins, as assessed with anti-phosphotyrosine immunoblots. However, thrombin-induced activation of protein kinase C and the production of thromboxane A2 were not altered by herbimycin A. Despite the absence of cytoskeletal pp60c-src enzyme activity, platelet shape change, aggregation, and serotonin release were unaltered following platelet stimulation with thrombin (0.05-1.0 unit/ml). Herbimycin A-treated platelets also demonstrated normal platelet aggregation in response to collagen (5 micrograms/ml), ionophore A23187 (2 microM), and ADP/adrenaline (10 microM each). However, the ability of herbimycin A-treated platelets to retract fibrin gels was significantly reduced. This defect in clot retraction was associated with reduced incorporation of integrin alpha IIb beta 3 into the cytoskeletal fraction of thrombin-aggregated platelets. Our studies suggest that tyrosine kinases in platelets regulate the cytoskeletal attachment of alpha IIb beta 3, as an essential process for the transmission of cellular contractile forces to fibrin polymers.
Collapse
Affiliation(s)
- S M Schoenwaelder
- Department of Medicine, Monash Medical School, Box Hill Hospital, Victoria, Australia
| | | | | | | | | | | |
Collapse
|
50
|
Jackson SP, Schoenwaelder SM, Yuan Y, Rabinowitz I, Salem HH, Mitchell CA. Adhesion receptor activation of phosphatidylinositol 3-kinase. von Willebrand factor stimulates the cytoskeletal association and activation of phosphatidylinositol 3-kinase and pp60c-src in human platelets. J Biol Chem 1994; 269:27093-9. [PMID: 7523416] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023] Open
Abstract
The cytoskeleton participates in the coordinated regulation of intracellular signaling molecules, following agonist stimulation of cells. We have demonstrated that von Willebrand factor (vWF) induced the cytoskeletal association and activation of phosphatidylinositol 3-kinase (PtdIns 3-kinase) in human platelets. The activation of PtdIns 3-kinase coincided with the tyrosine phosphorylation of multiple platelet proteins, as assessed by anti-phosphotyrosine immunoblotting. One of these tyrosine-phosphorylated proteins, pp60c-src, became specifically enriched in the cytoskeletal fraction of vWF-stimulated platelets. The vWF-stimulated cytoskeletal association of PtdIns 3-kinase and pp60c-src required platelet stirring and aggregation, was specifically blocked by an anti-GPIb monoclonal antibody, and was not observed in platelets lacking the glycoprotein Ib/IX complex (Bernard-Soulier syndrome). Pretreatment of normal platelets with 5 mM EDTA (37 degrees C for 90 min) or RGDS (2 mM), which disrupts the binding of various adhesive proteins to platelet integrins and inhibits fibrinogen-mediated platelet aggregation, did not alter the vWF-stimulated activation and cytoskeletal association of PtdIns 3-kinase and pp60c-src. Pretreatment of platelets with acetylsalicylic acid (1 mM) completely abolished vWF-stimulated production of thromboxane A2, dense granule release, and the activation of protein kinase C, without altering the activation and cytoskeletal translocation of PtdIns 3-kinase and pp60c-src. Our results suggest that vWF binding to the platelet adhesion receptor glycoprotein Ib/IX can mediate activation and translocation of both tyrosine and lipid kinase(s) independent of other agonists.
Collapse
Affiliation(s)
- S P Jackson
- Department of Medicine, Monash Medical School, Box Hill Hospital, Victoria, Australia
| | | | | | | | | | | |
Collapse
|