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Guinard I, Brassard-Jollive N, Ruch L, Weber J, Eckly A, Boscher J, Léon C. Mechanical confinement prevents ectopic platelet release. Proc Natl Acad Sci U S A 2024; 121:e2407829121. [PMID: 39236232 PMCID: PMC11420179 DOI: 10.1073/pnas.2407829121] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2024] [Accepted: 08/03/2024] [Indexed: 09/07/2024] Open
Abstract
Blood platelets are produced by megakaryocytes (MKs), their parent cells, which are in the bone marrow. Once mature, MK pierces through the sinusoid vessel, and the initial protrusion further elongates as proplatelet or buds to release platelets. The mechanisms controlling the decision to initiate proplatelet and platelet formation are unknown. Here, we show that the mechanical properties of the microenvironment prevent proplatelet and platelet release in the marrow stroma while allowing this process in the bloodstream. Loss of marrow confinement following myelosuppression led to inappropriate proplatelet and platelet release into the extravascular space. We further used an inert viscoelastic hydrogel to evaluate the impact of compressive stress. Transcriptional analysis showed that culture in three-dimensional gel induced upregulation of genes related to the Rho-GTPase pathway. We found higher Rho-GTPase activation, myosin light chain phosphorylation and F-actin under mechanical constraints while proplatelet formation was inhibited. The use of latrunculin-A to decrease F-actin promoted microtubule-dependent budding and proplatelet extension inside the gel. Additionally, ex vivo exposure of intact bone marrow to latrunculin-A triggered proplatelet extensions in the interstitial space. In vivo, this confinement-mediated high intracellular tension is responsible for the formation of the peripheral zone, a unique actin-rich structure. Cytoskeleton reorganization induces the disappearance of the peripheral zone upon reaching a liquid milieu to facilitate proplatelet and platelet formation. Hence, our data provide insight into the mechanisms preventing ectopic platelet release in the marrow stroma. Identifying such pathways is especially important for understanding pathologies altering marrow mechanics such as chemotherapy or myelofibrosis.
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Affiliation(s)
- Ines Guinard
- University of Strasbourg, INSERM, Etablissement Français du Sang (EFS) Grand-Est, UMR_S1255 Biologie et Pharmacologie des Plaquettes Sanguines (BPPS), FMTS, Strasbourg F-67065, France
| | - Noémie Brassard-Jollive
- University of Strasbourg, INSERM, Etablissement Français du Sang (EFS) Grand-Est, UMR_S1255 Biologie et Pharmacologie des Plaquettes Sanguines (BPPS), FMTS, Strasbourg F-67065, France
| | - Laurie Ruch
- University of Strasbourg, INSERM, Etablissement Français du Sang (EFS) Grand-Est, UMR_S1255 Biologie et Pharmacologie des Plaquettes Sanguines (BPPS), FMTS, Strasbourg F-67065, France
| | - Josiane Weber
- University of Strasbourg, INSERM, Etablissement Français du Sang (EFS) Grand-Est, UMR_S1255 Biologie et Pharmacologie des Plaquettes Sanguines (BPPS), FMTS, Strasbourg F-67065, France
| | - Anita Eckly
- University of Strasbourg, INSERM, Etablissement Français du Sang (EFS) Grand-Est, UMR_S1255 Biologie et Pharmacologie des Plaquettes Sanguines (BPPS), FMTS, Strasbourg F-67065, France
| | - Julie Boscher
- University of Strasbourg, INSERM, Etablissement Français du Sang (EFS) Grand-Est, UMR_S1255 Biologie et Pharmacologie des Plaquettes Sanguines (BPPS), FMTS, Strasbourg F-67065, France
| | - Catherine Léon
- University of Strasbourg, INSERM, Etablissement Français du Sang (EFS) Grand-Est, UMR_S1255 Biologie et Pharmacologie des Plaquettes Sanguines (BPPS), FMTS, Strasbourg F-67065, France
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2
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Antkowiak A, Batut J, Gaits-Iacovoni F. Linear podosomes display low Cdc42 activity for proplatelet elongation by megakaryocytes. Biochem Biophys Res Commun 2024; 734:150654. [PMID: 39241623 DOI: 10.1016/j.bbrc.2024.150654] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2024] [Revised: 08/26/2024] [Accepted: 09/02/2024] [Indexed: 09/09/2024]
Abstract
Blood platelets result from differentiation of megakaryocytes (MKs) into the bone marrow. It culminates with the extension of proplatelets (PPT) through medullar sinusoids and release of platelets in the blood stream. Those processes are regulated by contact with the microenvironment mediated by podosomes. We previously demonstrated that contact of megakaryocytes to Collagen I fibers initiated the formation of linear podosomes required for proplatelets extension and release of mature platelets. MKs linear podosomes have the particularity of displaying mechanical pulling activity but, unlike other linear podosomes, they lack the ability of digesting the extracellular matrix (ECM), as we recently demonstrated. The Cdc42 small GTPase is required for actomyosin-dependent maturation of the demarcation membrane system (DMS), a membrane reservoir for PPT and platelets components. Cdc42 is a known protein of the podosomes core, and is instrumental to accurate platelets release into the sinusoids. Indeed, FRET analysis showed that Cdc42 activity was very high and central to DMS formation. Unexpectedly, even though we found the protein in linear podosomes, almost undetectable Cdc42 activity was detected in those structures. This observation suggests that Cdc42 could also act as scaffold to assemble proteins required for PPT formation/elongation along Collagen I fibers in MKs. Eventually, we demonstrated that linear podosomes appear as points of contact between Collagen I fibers and DMS membranes, to mechanically extend PPT along Collagen bundles, independently of Cdc42 activity.
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Affiliation(s)
- Adrien Antkowiak
- Univ. Grenoble Alpes, Inserm, U1216, Grenoble Institut Neurosciences, 38000, Grenoble, France
| | - Julie Batut
- Unité de Biologie Moléculaire, Cellulaire et du Développement (MCD, UMR 5077), Centre de Biologie Intégrative (CBI, FR 3743), Université de Toulouse, CNRS, UPS, 118 Route de Narbonne F-31062, Toulouse, France
| | - Frédérique Gaits-Iacovoni
- Unité de Biologie Moléculaire, Cellulaire et du Développement (MCD, UMR 5077), Centre de Biologie Intégrative (CBI, FR 3743), Université de Toulouse, CNRS, UPS, 118 Route de Narbonne F-31062, Toulouse, France.
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3
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Carminita E, Becker IC, Italiano JE. What It Takes To Be a Platelet: Evolving Concepts in Platelet Production. Circ Res 2024; 135:540-549. [PMID: 39088641 DOI: 10.1161/circresaha.124.323579] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 08/03/2024]
Abstract
Platelets are among the most abundant cells within the circulation. Given that the platelet lifespan is 7 to 10 days in humans, a constant production of around 100 billion platelets per day is required. Platelet production from precursor cells called megakaryocytes is one of the most enigmatic processes in human biology. Although it has been studied for over a century, there is still controversy about the exact mechanisms leading to platelet release into circulation. The formation of proplatelet extensions from megakaryocytes into bone marrow sinusoids is the best-described mechanism explaining the origin of blood platelets. However, using powerful imaging techniques, several emerging studies have recently raised challenging questions in the field, suggesting that small platelet-sized structures called buds might also contribute to the circulating platelet pool. How and whether these structures differ from microvesicles or membrane blebs, which have previously been described to be released from megakaryocytes, is still a matter of discussion. In this review, we will summarize what the past and present have revealed about platelet production and whether mature blood platelets might emerge via different mechanisms.
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Affiliation(s)
- Estelle Carminita
- Vascular Biology Program, Boston Children's Hospital, Boston, MA (E.C., I.C.B., J.E.I.)
- Harvard Medical School, Boston, MA (E.C., I.C.B.)
| | - Isabelle C Becker
- Vascular Biology Program, Boston Children's Hospital, Boston, MA (E.C., I.C.B., J.E.I.)
- Harvard Medical School, Boston, MA (E.C., I.C.B.)
| | - Joseph E Italiano
- Vascular Biology Program, Boston Children's Hospital, Boston, MA (E.C., I.C.B., J.E.I.)
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4
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Liu H, Welburn JPI. A circle of life: platelet and megakaryocyte cytoskeleton dynamics in health and disease. Open Biol 2024; 14:240041. [PMID: 38835242 DOI: 10.1098/rsob.240041] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2024] [Accepted: 04/24/2024] [Indexed: 06/06/2024] Open
Abstract
Platelets are blood cells derived from megakaryocytes that play a central role in regulating haemostasis and vascular integrity. The microtubule cytoskeleton of megakaryocytes undergoes a critical dynamic reorganization during cycles of endomitosis and platelet biogenesis. Quiescent platelets have a discoid shape maintained by a marginal band composed of microtubule bundles, which undergoes remarkable remodelling during platelet activation, driving shape change and platelet function. Disrupting or enhancing this process can cause platelet dysfunction such as bleeding disorders or thrombosis. However, little is known about the molecular mechanisms underlying the reorganization of the cytoskeleton in the platelet lineage. Recent studies indicate that the emergence of a unique platelet tubulin code and specific pathogenic tubulin mutations cause platelet defects and bleeding disorders. Frequently, these mutations exhibit dominant negative effects, offering valuable insights into both platelet disease mechanisms and the functioning of tubulins. This review will highlight our current understanding of the role of the microtubule cytoskeleton in the life and death of platelets, along with its relevance to platelet disorders.
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Affiliation(s)
- Haonan Liu
- Wellcome Trust Centre for Cell Biology, School of Biological Sciences, University of Edinburgh, Edinburgh EH9 3BF, UK
| | - Julie P I Welburn
- Wellcome Trust Centre for Cell Biology, School of Biological Sciences, University of Edinburgh, Edinburgh EH9 3BF, UK
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5
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Kim OV, Litvinov RI, Gagne AL, French DL, Brass LF, Weisel JW. Megakaryocyte-induced contraction of plasma clots: cellular mechanisms and structural mechanobiology. Blood 2024; 143:548-560. [PMID: 37944157 PMCID: PMC11033616 DOI: 10.1182/blood.2023021545] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2023] [Revised: 10/17/2023] [Accepted: 11/02/2023] [Indexed: 11/12/2023] Open
Abstract
ABSTRACT Nonmuscle cell contractility is an essential feature underlying diverse cellular processes such as motility, morphogenesis, division and genome replication, intracellular transport, and secretion. Blood clot contraction is a well-studied process driven by contracting platelets. Megakaryocytes (MKs), which are the precursors to platelets, can be found in bone marrow and lungs. Although they express many of the same proteins and structures found in platelets, little is known about their ability to engage with extracellular proteins such as fibrin and contract. Here, we have measured the ability of MKs to compress plasma clots. Megakaryocytes derived from human induced pluripotent stem cells (iPSCs) were suspended in human platelet-free blood plasma and stimulated with thrombin. Using real-time macroscale optical tracking, confocal microscopy, and biomechanical measurements, we found that activated iPSC-derived MKs (iMKs) caused macroscopic volumetric clot shrinkage, as well as densification and stiffening of the fibrin network via fibrin-attached plasma membrane protrusions undergoing extension-retraction cycles that cause shortening and bending of fibrin fibers. Contraction induced by iMKs involved 2 kinetic phases with distinct rates and durations. It was suppressed by inhibitors of nonmuscle myosin IIA, actin polymerization, and integrin αIIbβ3-fibrin interactions, indicating that the molecular mechanisms of iMK contractility were similar or identical to those in activated platelets. Our findings provide new insights into MK biomechanics and suggest that iMKs can be used as a model system to study platelet contractility. Physiologically, the ability of MKs to contract plasma clots may play a role in the mechanical remodeling of intravascular blood clots and thrombi.
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Affiliation(s)
- Oleg V. Kim
- Department of Cell and Developmental Biology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA
- Department of Biomedical Engineering and Mechanics, Fralin Biomedical Research Institute, Center for Soft Matter and Biological Physics, Virginia Tech, Blacksburg, VA
| | - Rustem I. Litvinov
- Department of Cell and Developmental Biology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA
| | - Alyssa L. Gagne
- Center for Cellular and Molecular Therapeutics, The Children’s Hospital of Philadelphia, Philadelphia, PA
| | - Deborah L. French
- Department of Pathology and Laboratory Medicine, The Children’s Hospital of Philadelphia, Philadelphia, PA
| | - Lawrence F. Brass
- Division of Hematology and Oncology, Department of Medicine, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA
| | - John W. Weisel
- Department of Cell and Developmental Biology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA
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6
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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] [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.
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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
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7
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Puhm F, Laroche A, Boilard E. Diversity of Megakaryocytes. Arterioscler Thromb Vasc Biol 2023; 43:2088-2098. [PMID: 37675634 DOI: 10.1161/atvbaha.123.318782] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2023] [Accepted: 08/14/2023] [Indexed: 09/08/2023]
Abstract
Megakaryocytes are commonly known as large, polyploid, bone marrow resident cells that contribute to hemostasis through the production of platelets. Soon after their discovery in the 19th century, megakaryocytes were described in tissue locations other than the bone marrow, specifically in the lungs and the blood circulation. However, the localization of megakaryocytes in the lungs and the contribution of lung megakaryocytes to the general platelet pool has only recently been appreciated. Moreover, the conception of megakaryocytes as uniform cells with the sole purpose of platelet production has been challenged. Here, we review the literature on megakaryocyte cell identity and location with a special focus on recent observations of megakaryocyte subpopulations identified by transcriptomic analyses.
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Affiliation(s)
- Florian Puhm
- Department of Infectious Diseases and Immunity, Centre de Recherche du Centre Hospitalier Universitaire de Québec - Université Laval, Canada (F.P., A.L., E.B.)
- Centre de Recherche ARThrite, Faculté de Médecine de l'Université Laval, Québec, Canada (F.P., A.L., E.B.)
| | - Audrée Laroche
- Department of Infectious Diseases and Immunity, Centre de Recherche du Centre Hospitalier Universitaire de Québec - Université Laval, Canada (F.P., A.L., E.B.)
- Centre de Recherche ARThrite, Faculté de Médecine de l'Université Laval, Québec, Canada (F.P., A.L., E.B.)
| | - Eric Boilard
- Department of Infectious Diseases and Immunity, Centre de Recherche du Centre Hospitalier Universitaire de Québec - Université Laval, Canada (F.P., A.L., E.B.)
- Centre de Recherche ARThrite, Faculté de Médecine de l'Université Laval, Québec, Canada (F.P., A.L., E.B.)
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8
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Scherlinger M, Richez C, Tsokos GC, Boilard E, Blanco P. The role of platelets in immune-mediated inflammatory diseases. Nat Rev Immunol 2023; 23:495-510. [PMID: 36707719 PMCID: PMC9882748 DOI: 10.1038/s41577-023-00834-4] [Citation(s) in RCA: 51] [Impact Index Per Article: 51.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 12/15/2022] [Indexed: 01/28/2023]
Abstract
Immune-mediated inflammatory diseases (IMIDs) are characterized by excessive and uncontrolled inflammation and thrombosis, both of which are responsible for organ damage, morbidity and death. Platelets have long been known for their role in primary haemostasis, but they are now also considered to be components of the immune system and to have a central role in the pathogenesis of IMIDs. In patients with IMIDs, platelets are activated by disease-specific factors, and their activation often reflects disease activity. Here we summarize the evidence showing that activated platelets have an active role in the pathogenesis and the progression of IMIDs. Activated platelets produce soluble factors and directly interact with immune cells, thereby promoting an inflammatory phenotype. Furthermore, platelets participate in tissue injury and promote abnormal tissue healing, leading to fibrosis. Targeting platelet activation and targeting the interaction of platelets with the immune system are novel and promising therapeutic strategies in IMIDs.
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Affiliation(s)
- Marc Scherlinger
- Service de Rhumatologie, Centre de référence des maladies auto-immunes systémiques rares RESO, Hôpitaux Universitaires de Strasbourg, Strasbourg, France.
- Department of Medicine, Beth Israel Deaconess Medical Center, Boston, MA, USA.
- Laboratoire d'ImmunoRhumatologie Moléculaire UMR_S 1109, Institut National de la Santé et de la Recherche Médicale (INSERM), Strasbourg, France.
| | - Christophe Richez
- Service de Rhumatologie, Centre de référence des maladies auto-immunes systémiques rares RESO, Hôpital Pellegrin, Centre Hospitalier Universitaire, Bordeaux, France
- CNRS-UMR 5164, ImmunoConcept, Université de Bordeaux, Bordeaux, France
| | - George C Tsokos
- Department of Medicine, Beth Israel Deaconess Medical Center, Boston, MA, USA
| | - Eric Boilard
- Centre de Recherche du Centre Hospitalier Universitaire de Québec-Université Laval, Quebec City, Quebec, Canada
- Centre de Recherche ARThrite, Université Laval, Quebec City, Quebec, Canada
| | - Patrick Blanco
- CNRS-UMR 5164, ImmunoConcept, Université de Bordeaux, Bordeaux, France.
- Laboratoire d'Immunologie et Immunogénétique, FHU ACRONIM, Hôpital Pellegrin, Centre Hospitalier Universitaire, Bordeaux, France.
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9
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Di Buduo CA, Miguel CP, Balduini A. Inside-to-outside and back to the future of megakaryopoiesis. Res Pract Thromb Haemost 2023; 7:100197. [PMID: 37416054 PMCID: PMC10320384 DOI: 10.1016/j.rpth.2023.100197] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2023] [Revised: 04/12/2023] [Accepted: 04/23/2023] [Indexed: 07/08/2023] Open
Abstract
A State of the Art lecture titled "Megakaryocytes and different thrombopoietic environments" was presented at the ISTH Congress in 2022. Circulating platelets are specialized cells produced by megakaryocytes. Leading studies point to the bone marrow niche as the core of hematopoietic stem cell differentiation, revealing interesting and complex environmental factors for consideration. Megakaryocytes take cues from the physiochemical bone marrow microenvironment, which includes cell-cell interactions, contact with extracellular matrix components, and flow generated by blood circulation in the sinusoidal lumen. Germinal and acquired mutations in hematopoietic stem cells may manifest in altered megakaryocyte maturation, proliferation, and platelet production. Diseased megakaryopoiesis may also cause modifications of the entire hematopoietic niche, highlighting the central role of megakaryocytes in the control of physiologic bone marrow homeostasis. Tissue-engineering approaches have been developed to translate knowledge from in vivo (inside) to functional mimics of native tissue ex vivo (outside). Reproducing the thrombopoietic environment is instrumental to gain new insight into its activity and answering the growing demand for human platelets for fundamental studies and clinical applications. In this review, we discuss the major achievements on this topic, and finally, we summarize relevant new data presented during the 2022 ISTH Congress that pave the road to the future of megakaryopoiesis.
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Affiliation(s)
| | | | - Alessandra Balduini
- Department of Molecular Medicine, University of Pavia, Pavia, Italy
- Department of Biomedical Engineering, Tufts University, Medford, Massachusetts, USA
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10
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Deciphering actin remodelling in immune cells through the prism of actin-related inborn errors of immunity. Eur J Cell Biol 2023; 102:151283. [PMID: 36525824 DOI: 10.1016/j.ejcb.2022.151283] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2022] [Revised: 11/14/2022] [Accepted: 11/14/2022] [Indexed: 12/14/2022] Open
Abstract
Actin cytoskeleton remodelling drives cell motility, cell to cell contacts, as well as membrane and organelle dynamics. Those cellular activities operate at a particularly high pace in immune cells since these cells migrate through various tissues, interact with multiple cellular partners, ingest microorganisms and secrete effector molecules. The central and multifaceted role of actin cytoskeleton remodelling in sustaining immune cell tasks in humans is highlighted by rare inborn errors of immunity due to mutations in genes encoding proximal and distal actin regulators. In line with the specificity of some of the actin-based processes at work in immune cells, the expression of some of the affected genes, such as WAS, ARPC1B and HEM1 is restricted to the hematopoietic compartment. Exploration of these natural deficiencies highlights the fact that the molecular control of actin remodelling is tuned distinctly in the various subsets of myeloid and lymphoid immune cells and sustains different networks associated with a vast array of specialized tasks. Furthermore, defects in individual actin remodelling proteins are usually associated with partial cellular impairments highlighting the plasticity of actin cytoskeleton remodelling. This review covers the roles of disease-associated actin regulators in promoting the actin-based processes of immune cells. It focuses on the specific molecular function of those regulators across various immune cell subsets and in response to different stimuli. Given the fact that numerous immune-related actin defects have only been characterized recently, we further discuss the challenges lying ahead to decipher the underlying patho-mechanisms.
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11
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Gelon L, Fromont L, Lefrançais E. Occurrence and role of lung megakaryocytes in infection and inflammation. Front Immunol 2022; 13:1029223. [PMID: 36524131 PMCID: PMC9745136 DOI: 10.3389/fimmu.2022.1029223] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2022] [Accepted: 11/09/2022] [Indexed: 12/03/2022] Open
Abstract
Megakaryocytes (MKs) are large cells giving rise to platelets. It is well established that in adults, MKs develop from hematopoietic stem cells and reside in the bone marrow. MKs are also rare but normal constituents of the venous blood returning to the lungs, and MKs are found in the lung vasculature (MKcirc), suggesting that these cells are migrants from the bone marrow and get trapped in lung capillaries where the final steps of platelet production can occur. An unprecedented increase in the number of lung and circulating MKs was described in coronavirus disease 2019 (COVID-19) patients, suggesting that lung thrombopoiesis may be increased during lung infection and/or thromboinflammation. In addition to the population of platelet-producing intravascular MKs in the lung, a population of lung-resident megakaryocytes (MKL) has been identified and presents a specific immune signature compared to its bone marrow counterparts. Recent single-cell analysis and intravital imaging have helped us gain a better understanding of these populations in mouse and human. This review aims at summarizing the recent data on increased occurrence of lung MKs and discusses their origin, specificities, and potential role in homeostasis and inflammatory and infectious lung diseases. Here, we address remaining questions, controversies, and methodologic challenges for further studies of both MKcirc and MKL.
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12
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Novel insights into mouse models of ectopic proplatelet release. Blood Adv 2022; 6:6135-6139. [PMID: 36251748 PMCID: PMC9768245 DOI: 10.1182/bloodadvances.2022007824] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2022] [Revised: 09/01/2022] [Accepted: 09/04/2022] [Indexed: 12/31/2022] Open
Abstract
Mature bone marrow (BM) megakaryocytes (MKs) produce platelets by extending proplatelets into sinusoidal blood vessels. Defects in this process can lead to thrombocytopenia and increased risk of bleeding. Mice lacking the actin-regulatory proteins Profilin 1 (PFN1), Wiskott-Aldrich Syndrome protein (WASp), Actin Related Protein 2/3 complex (Arp2/3), or adhesion and degranulation-promoting adapter protein (ADAP) display thrombocytopenia and ectopic release of (pro)platelet-like particles into the BM compartment, pointing to an important axis of actin-mediated directional proplatelet formation. The mechanism underlying ectopic release in these mice is still not completely understood. However, we hypothesized that similar functional defects account for this observation. We analyzed WASp-, ADAP-, PFN1-, and ARPC2-knockout mice to determine the role of actin reorganization and integrin activation in directional proplatelet formation. ADAP-, ARPC2-, and PFN1-deficient MKs displayed reduced adhesion to collagen, defective F-actin organization, and diminished β1-integrin activation. WASp-deficient MKs showed the strongest reduction in the adhesion assay of collagen and altered F-actin organization with reduced podosome formation. Our results indicate that ADAP, PFN1, WASp, and ARP2/3 are part of the same pathway that regulates polarization processes in MKs and directional proplatelet formation into BM sinusoids.
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13
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Englert M, Aurbach K, Becker IC, Gerber A, Heib T, Wackerbarth LM, Kusch C, Mott K, Araujo GHM, Baig AA, Dütting S, Knaus UG, Stigloher C, Schulze H, Nieswandt B, Pleines I, Nagy Z. Impaired microtubule dynamics contribute to microthrombocytopenia in RhoB-deficient mice. Blood Adv 2022; 6:5184-5197. [PMID: 35819450 PMCID: PMC9631634 DOI: 10.1182/bloodadvances.2021006545] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2021] [Accepted: 06/30/2022] [Indexed: 11/30/2022] Open
Abstract
Megakaryocytes are large cells in the bone marrow that give rise to blood platelets. Platelet biogenesis involves megakaryocyte maturation, the localization of the mature cells in close proximity to bone marrow sinusoids, and the formation of protrusions, which are elongated and shed within the circulation. Rho GTPases play important roles in platelet biogenesis and function. RhoA-deficient mice display macrothrombocytopenia and a striking mislocalization of megakaryocytes into bone marrow sinusoids and a specific defect in G-protein signaling in platelets. However, the role of the closely related protein RhoB in megakaryocytes or platelets remains unknown. In this study, we show that, in contrast to RhoA deficiency, genetic ablation of RhoB in mice results in microthrombocytopenia (decreased platelet count and size). RhoB-deficient platelets displayed mild functional defects predominantly upon induction of the collagen/glycoprotein VI pathway. Megakaryocyte maturation and localization within the bone marrow, as well as actin dynamics, were not affected in the absence of RhoB. However, in vitro-generated proplatelets revealed pronouncedly impaired microtubule organization. Furthermore, RhoB-deficient platelets and megakaryocytes displayed selective defects in microtubule dynamics/stability, correlating with reduced levels of acetylated α-tubulin. Our findings imply that the reduction of this tubulin posttranslational modification results in impaired microtubule dynamics, which might contribute to microthrombocytopenia in RhoB-deficient mice. Importantly, we demonstrate that RhoA and RhoB are localized differently and have selective, nonredundant functions in the megakaryocyte lineage.
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Affiliation(s)
- Maximilian Englert
- Institute of Experimental Biomedicine, University Hospital, University of Würzburg, Würzburg, Germany
- Rudolf Virchow Center for Integrative and Translational Bioimaging, University of Würzburg, Würzburg, Germany
| | - Katja Aurbach
- Institute of Experimental Biomedicine, University Hospital, University of Würzburg, Würzburg, Germany
- Rudolf Virchow Center for Integrative and Translational Bioimaging, University of Würzburg, Würzburg, Germany
| | - Isabelle C. Becker
- Institute of Experimental Biomedicine, University Hospital, University of Würzburg, Würzburg, Germany
- Rudolf Virchow Center for Integrative and Translational Bioimaging, University of Würzburg, Würzburg, Germany
| | - Annika Gerber
- Institute of Experimental Biomedicine, University Hospital, University of Würzburg, Würzburg, Germany
- Rudolf Virchow Center for Integrative and Translational Bioimaging, University of Würzburg, Würzburg, Germany
| | - Tobias Heib
- Institute of Experimental Biomedicine, University Hospital, University of Würzburg, Würzburg, Germany
- Rudolf Virchow Center for Integrative and Translational Bioimaging, University of Würzburg, Würzburg, Germany
| | - Lou M. Wackerbarth
- Institute of Experimental Biomedicine, University Hospital, University of Würzburg, Würzburg, Germany
- Rudolf Virchow Center for Integrative and Translational Bioimaging, University of Würzburg, Würzburg, Germany
| | - Charly Kusch
- Institute of Experimental Biomedicine, University Hospital, University of Würzburg, Würzburg, Germany
- Rudolf Virchow Center for Integrative and Translational Bioimaging, University of Würzburg, Würzburg, Germany
| | - Kristina Mott
- Institute of Experimental Biomedicine, University Hospital, University of Würzburg, Würzburg, Germany
| | - Gabriel H. M. Araujo
- Institute of Experimental Biomedicine, University Hospital, University of Würzburg, Würzburg, Germany
- Rudolf Virchow Center for Integrative and Translational Bioimaging, University of Würzburg, Würzburg, Germany
| | - Ayesha A. Baig
- Institute of Experimental Biomedicine, University Hospital, University of Würzburg, Würzburg, Germany
- Rudolf Virchow Center for Integrative and Translational Bioimaging, University of Würzburg, Würzburg, Germany
| | - Sebastian Dütting
- Institute of Experimental Biomedicine, University Hospital, University of Würzburg, Würzburg, Germany
- Rudolf Virchow Center for Integrative and Translational Bioimaging, University of Würzburg, Würzburg, Germany
| | - Ulla G. Knaus
- Conway Institute, School of Medicine, University College Dublin, Dublin, Ireland; and
| | | | - Harald Schulze
- Institute of Experimental Biomedicine, University Hospital, University of Würzburg, Würzburg, Germany
| | - Bernhard Nieswandt
- Institute of Experimental Biomedicine, University Hospital, University of Würzburg, Würzburg, Germany
- Rudolf Virchow Center for Integrative and Translational Bioimaging, University of Würzburg, Würzburg, Germany
| | - Irina Pleines
- Institute of Experimental Biomedicine, University Hospital, University of Würzburg, Würzburg, Germany
- Rudolf Virchow Center for Integrative and Translational Bioimaging, University of Würzburg, Würzburg, Germany
| | - Zoltan Nagy
- Institute of Experimental Biomedicine, University Hospital, University of Würzburg, Würzburg, Germany
- Rudolf Virchow Center for Integrative and Translational Bioimaging, University of Würzburg, Würzburg, Germany
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14
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Tilburg J, Becker IC, Italiano JE. Don't you forget about me(gakaryocytes). Blood 2022; 139:3245-3254. [PMID: 34582554 PMCID: PMC9164737 DOI: 10.1182/blood.2020009302] [Citation(s) in RCA: 15] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2021] [Accepted: 09/08/2021] [Indexed: 11/20/2022] Open
Abstract
Platelets (small, anucleate cell fragments) derive from large precursor cells, megakaryocytes (MKs), that reside in the bone marrow. MKs emerge from hematopoietic stem cells in a complex differentiation process that involves cytoplasmic maturation, including the formation of the demarcation membrane system, and polyploidization. The main function of MKs is the generation of platelets, which predominantly occurs through the release of long, microtubule-rich proplatelets into vessel sinusoids. However, the idea of a 1-dimensional role of MKs as platelet precursors is currently being questioned because of advances in high-resolution microscopy and single-cell omics. On the one hand, recent findings suggest that proplatelet formation from bone marrow-derived MKs is not the only mechanism of platelet production, but that it may also occur through budding of the plasma membrane and in distant organs such as lung or liver. On the other hand, novel evidence suggests that MKs not only maintain physiological platelet levels but further contribute to bone marrow homeostasis through the release of extracellular vesicles or cytokines, such as transforming growth factor β1 or platelet factor 4. The notion of multitasking MKs was reinforced in recent studies by using single-cell RNA sequencing approaches on MKs derived from adult and fetal bone marrow and lungs, leading to the identification of different MK subsets that appeared to exhibit immunomodulatory or secretory roles. In the following article, novel insights into the mechanisms leading to proplatelet formation in vitro and in vivo will be reviewed and the hypothesis of MKs as immunoregulatory cells will be critically discussed.
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Affiliation(s)
- Julia Tilburg
- Vascular Biology Program, Boston Children's Hospital, Boston, MA
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15
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Lee RH, Ghalloussi D, Harousseau GL, Kenny JP, Kramer PA, Proamer F, Nieswandt B, Flick MJ, Gachet C, Casari C, Eckly A, Bergmeier W. Rasa3 deficiency minimally affects thrombopoiesis but promotes severe thrombocytopenia due to integrin-dependent platelet clearance. JCI Insight 2022; 7:e155676. [PMID: 35290242 PMCID: PMC9089782 DOI: 10.1172/jci.insight.155676] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2021] [Accepted: 03/09/2022] [Indexed: 01/26/2023] Open
Abstract
Platelet homeostasis is dependent on a tight regulation of both platelet production and clearance. The small GTPase Rap1 mediates platelet adhesion and hemostatic plug formation. However, Rap1 signaling is also critical for platelet homeostasis as both Rap1 deficiency and uninhibited Rap1 signaling lead to marked thrombocytopenia in mice. Here, we investigated the mechanism by which deficiency in Rasa3, a critical negative regulator of Rap1, causes macrothrombocytopenia in mice. Despite marked morphological and ultrastructural abnormalities, megakaryocytes in hypomorphic Rasa3hlb/hlb (R3hlb/hlb) or Rasa3-/- mice demonstrated robust proplatelet formation in vivo, suggesting that defective thrombopoiesis is not the main cause of thrombocytopenia. Rather, we observed that R3hlb/hlb platelets became trapped in the spleen marginal zone/red pulp interface, with evidence of platelet phagocytosis by macrophages. Clearance of mutant platelets was also observed in the liver, especially in splenectomized mice. Platelet count and platelet life span in Rasa3-mutant mice were restored by genetic or pharmacological approaches to inhibit the Rap1/talin1/αIIbβ3 integrin axis. A similar pattern of splenic clearance was observed in mice injected with anti-αIIbβ3 but not anti-glycoprotein Ibα platelet-depleting antibodies. In summary, we describe a potentially novel, integrin-based mechanism of platelet clearance that could be critical for our understanding of select inherited and acquired thrombocytopenias.
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Affiliation(s)
- Robert H. Lee
- Department of Biochemistry and Biophysics and
- Blood Research Center, School of Medicine, University of North Carolina at Chapel Hill, North Carolina, USA
| | - Dorsaf Ghalloussi
- Department of Biochemistry and Biophysics and
- Blood Research Center, School of Medicine, University of North Carolina at Chapel Hill, North Carolina, USA
| | | | | | | | - Fabienne Proamer
- Université de Strasbourg, INSERM, EFS Grand Est, BPPS UMR-S 1255, FMTS, F-67065 Strasbourg, France
| | - Bernhard Nieswandt
- Institute of Experimental Biomedicine I, University Hospital Würzburg, Würzburg, Germany
- Rudolf Virchow Center, University of Würzburg, Würzburg, Germany
| | - Matthew J. Flick
- Blood Research Center, School of Medicine, University of North Carolina at Chapel Hill, North Carolina, USA
- Department of Pathology and Laboratory Medicine, School of Medicine, University of North Carolina at Chapel Hill, North Carolina, USA
| | - Christian Gachet
- Université de Strasbourg, INSERM, EFS Grand Est, BPPS UMR-S 1255, FMTS, F-67065 Strasbourg, France
| | - Caterina Casari
- Department of Biochemistry and Biophysics and
- HITh, UMR_S1176, INSERM, Université Paris-Saclay, Le Kremlin-Bicêtre, France
| | - Anita Eckly
- Université de Strasbourg, INSERM, EFS Grand Est, BPPS UMR-S 1255, FMTS, F-67065 Strasbourg, France
| | - Wolfgang Bergmeier
- Department of Biochemistry and Biophysics and
- Blood Research Center, School of Medicine, University of North Carolina at Chapel Hill, North Carolina, USA
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16
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Oprescu A, Michel D, Antkowiak A, Vega E, Viaud J, Courtneidge SA, Eckly A, de la Salle H, Chicanne G, Léon C, Payrastre B, Gaits-Iacovoni F. Megakaryocytes form linear podosomes devoid of digestive properties to remodel medullar matrix. Sci Rep 2022; 12:6255. [PMID: 35428815 PMCID: PMC9012751 DOI: 10.1038/s41598-022-10215-x] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2021] [Accepted: 04/01/2022] [Indexed: 12/20/2022] Open
Abstract
Bone marrow megakaryocytes (MKs) undergo a maturation involving contacts with the microenvironment before extending proplatelets through sinusoids to deliver platelets in the bloodstream. We demonstrated that MKs assemble linear F-actin-enriched podosomes on collagen I fibers. Microscopy analysis evidenced an inverse correlation between the number of dot-like versus linear podosomes over time. Confocal videomicroscopy confirmed that they derived from each-other. This dynamics was dependent on myosin IIA. Importantly, MKs progenitors expressed the Tks4/5 adaptors, displayed a strong gelatinolytic ability and did not form linear podosomes. While maturing, MKs lost Tks expression together with digestive ability. However, those MKs were still able to remodel the matrix by exerting traction on collagen I fibers through a collaboration between GPVI, ß1 integrin and linear podosomes. Our data demonstrated that a change in structure and composition of podosomes accounted for the shift of function during megakaryopoiesis. These data highlight the fact that members of the invadosome family could correspond to different maturation status of the same entity, to adapt to functional responses required by differentiation stages of the cell that bears them.
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Affiliation(s)
- Antoine Oprescu
- INSERM, UMR1297, Université Toulouse III, Institut des Maladies Métaboliques et Cardiovasculaires, Toulouse, France
| | - Déborah Michel
- INSERM, UMR1297, Université Toulouse III, Institut des Maladies Métaboliques et Cardiovasculaires, Toulouse, France
| | - Adrien Antkowiak
- INSERM, UMR1297, Université Toulouse III, Institut des Maladies Métaboliques et Cardiovasculaires, Toulouse, France
| | - Elodie Vega
- INSERM, UMR1297, Université Toulouse III, Institut des Maladies Métaboliques et Cardiovasculaires, Toulouse, France
| | - Julien Viaud
- INSERM, UMR1297, Université Toulouse III, Institut des Maladies Métaboliques et Cardiovasculaires, Toulouse, France
| | - Sara A Courtneidge
- Department of Cell, Development and Cancer Biology, Oregon Health & Science University, Oregon, USA
| | - Anita Eckly
- INSERM, UMR_S1255, Université de Strasbourg, Etablissement Français du Sang-GEST, Strasbourg, France
| | - Henri de la Salle
- INSERM, UMR_S1255, Université de Strasbourg, Etablissement Français du Sang-GEST, Strasbourg, France
| | - Gaëtan Chicanne
- INSERM, UMR1297, Université Toulouse III, Institut des Maladies Métaboliques et Cardiovasculaires, Toulouse, France
| | - Catherine Léon
- INSERM, UMR_S1255, Université de Strasbourg, Etablissement Français du Sang-GEST, Strasbourg, France
| | - Bernard Payrastre
- INSERM, UMR1297, Université Toulouse III, Institut des Maladies Métaboliques et Cardiovasculaires, Toulouse, France.,CHU de Toulouse, laboratoire d'Hématologie, Toulouse, France
| | - Frédérique Gaits-Iacovoni
- INSERM, UMR1297, Université Toulouse III, Institut des Maladies Métaboliques et Cardiovasculaires, Toulouse, France. .,Molecular, Cellular and Developmental Biology Department (MCD, UMR5077), Centre de Biologie Intégrative (CBI, FR3743), University of Toulouse, CNRS, UPS, 31062, Toulouse, France.
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17
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Factors Associated with Platelet Activation-Recent Pharmaceutical Approaches. Int J Mol Sci 2022; 23:ijms23063301. [PMID: 35328719 PMCID: PMC8955963 DOI: 10.3390/ijms23063301] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2022] [Revised: 03/16/2022] [Accepted: 03/17/2022] [Indexed: 02/06/2023] Open
Abstract
Platelets are at the forefront of human health and disease following the advances in their research presented in past decades. Platelet activation, their most crucial function, although beneficial in the case of vascular injury, may represent the initial step for thrombotic complications characterizing various pathologic states, primarily atherosclerotic cardiovascular diseases. In this review, we initially summarize the structural and functional characteristics of platelets. Next, we focus on the process of platelet activation and its associated factors, indicating the potential molecular mechanisms involving inflammation, endothelial dysfunction, and miRs. Finally, an overview of the available antiplatelet agents is being portrayed, together with agents possessing off-set platelet-inhibitory actions, while an extensive presentation of drugs under investigation is being given.
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18
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Deletion of Grin1 in mouse megakaryocytes reveals NMDA receptor role in platelet function and proplatelet formation. Blood 2022; 139:2673-2690. [PMID: 35245376 DOI: 10.1182/blood.2021014000] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2021] [Accepted: 02/18/2022] [Indexed: 11/20/2022] Open
Abstract
The process of proplatelet formation (PPF) requires coordinated interaction between megakaryocytes (MKs) and the extracellular matrix (ECM), followed by a dynamic reorganization of the actin and microtubule cytoskeleton. Localized fluxes of intracellular calcium ions (Ca2+) facilitate MK-ECM interaction and PPF. Glutamate-gated N-methyl-D--aspartate receptor (NMDAR) is highly permeable to Ca2+. NMDAR antagonists inhibit MK maturation ex vivo, however there is no in vivo data. Using the Cre-loxP system, we generated a platelet lineage-specific knockout mouse model of reduced NMDAR function in MKs and platelets (Pf4-Grin1-/- mice). Effects of NMDAR deletion were examined using well-established assays of platelet function and production in vivo and ex vivo. We found that Pf4-Grin1-/- mice had defects in megakaryopoiesis, thrombopoiesis and platelet function, which manifested as reduced platelet counts, lower rates of platelet production in the immune model of thrombocytopenia, and a prolonged tail bleeding time. Platelet activation was impaired to a range of agonists associated with reduced Ca2+ responses, including metabotropic-like, and defective platelet spreading. MKs showed reduced colony and proplatelet formation. Impaired reorganization of intracellular F-actin and α-tubulin was identified as the main cause of reduced platelet function and production. Pf4-Grin1-/- MKs also had lower levels of transcripts encoding crucial ECM elements and enzymes, suggesting NMDAR signaling is involved in ECM remodeling. In summary, we provide the first genetic evidence that NMDAR plays an active role in platelet function and production. NMDARs regulate PPF through the mechanism that involves MK-ECM interaction and cytoskeletal reorganization. Our results suggest that NMDAR helps guide PPF in vivo.
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19
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Yang X, Chitalia SV, Matsuura S, Ravid K. Integrins and their role in megakaryocyte development and function. Exp Hematol 2022; 106:31-39. [PMID: 34910941 PMCID: PMC8795491 DOI: 10.1016/j.exphem.2021.11.007] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2021] [Accepted: 11/24/2021] [Indexed: 02/03/2023]
Abstract
Mature megakaryocytes, the platelet precursors, originate from hematopoietic stem cell progenitors, which, once committed to this lineage, undergo endomitosis leading to polyploidization. The process entails repeated rounds of DNA replication without cell division, yielding polyploid cells. Supporting the cell's developmental process and various cellular functions are integrin receptors, a conduit of communication between the extracellular environment and the cell actin cytoskeleton. Integrins are heterodimers of α and β subunits, where different combinations of the known 18 α and 8 β subunits confer specificity to the receptor. Integrin ligands range from extracellular matrices through soluble ligands, infectious agents, and counterreceptors, to cells. In this review, we describe the different integrins expressed on bone marrow megakaryocytes and their attributed roles in lineage development and cellular functions, including adhesion, spreading, proplatelet formation, and functional interaction with other cells. Pathologies associated with dysregulated megakaryocyte integrin expression are also reviewed.
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Affiliation(s)
- Xiaosheng Yang
- Department of Medicine and Whitaker Cardiovascular Institute, Boston University School of Medicine, Boston, MA, 02118
| | - Shlok V. Chitalia
- Department of Medicine and Whitaker Cardiovascular Institute, Boston University School of Medicine, Boston, MA, 02118
| | - Shinobu Matsuura
- Department of Medicine and Whitaker Cardiovascular Institute, Boston University School of Medicine, Boston, MA, 02118
| | - Katya Ravid
- Department of Medicine and Whitaker Cardiovascular Institute, Boston University School of Medicine, Boston, MA, 02118,To whom correspondence should be addressed: Katya Ravid, Boston University School of Medicine, 700 Albany St, W-6, Boston, MA 02118, Tel: (617)358-8042,
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20
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The bone marrow niche from the inside out: how megakaryocytes are shaped by and shape hematopoiesis. Blood 2022; 139:483-491. [PMID: 34587234 PMCID: PMC8938937 DOI: 10.1182/blood.2021012827] [Citation(s) in RCA: 16] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2021] [Accepted: 09/10/2021] [Indexed: 01/29/2023] Open
Abstract
Megakaryocytes (MKs), the largest of the hematopoietic cells, are responsible for producing platelets by extending and depositing long proplatelet extensions into the bloodstream. The traditional view of megakaryopoiesis describes the cellular journey from hematopoietic stem cells (HSCs) along the myeloid branch of hematopoiesis. However, recent studies suggest that MKs can be generated from multiple pathways, some of which do not require transit through multipotent or bipotent MK-erythroid progenitor stages in steady-state and emergency conditions. Growing evidence suggests that these emergency conditions are due to stress-induced molecular changes in the bone marrow (BM) microenvironment, also called the BM niche. These changes can result from insults that affect the BM cellular composition, microenvironment, architecture, or a combination of these factors. In this review, we explore MK development, focusing on recent studies showing that MKs can be generated from multiple divergent pathways. We highlight how the BM niche may encourage and alter these processes using different mechanisms of communication, such as direct cell-to-cell contact, secreted molecules (autocrine and paracrine signaling), and the release of cellular components (eg, extracellular vesicles). We also explore how MKs can actively build and shape the surrounding BM niche.
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21
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Neutrophil transit time and localization within the megakaryocyte define morphologically distinct forms of emperipolesis. Blood Adv 2021; 6:2081-2091. [PMID: 34872109 PMCID: PMC9006297 DOI: 10.1182/bloodadvances.2021005097] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2021] [Accepted: 11/10/2021] [Indexed: 11/30/2022] Open
Abstract
Emperipolesis (neutrophil transit through megakaryocytes) occurs in fast and slow forms that differ morphologically. Intramegakaryocytic neutrophils reside in emperisomes and in cytoplasm near the demarcation membrane system, endoplasmic reticulum, and nucleus.
Neutrophils transit through megakaryocytes in a process termed emperipolesis, but it is unknown whether this interaction is a single type of cell-in-cell interaction or a set of distinct processes. Using a murine in vitro model, we characterized emperipolesis by live-cell spinning disk microscopy and electron microscopy. Approximately half of neutrophils exited the megakaryocyte rapidly, typically in 10 minutes or less, displaying ameboid morphology as they passed through the host cell (fast emperipolesis). The remaining neutrophils assumed a sessile morphology, most remaining within the megakaryocyte for at least 60 minutes (slow emperipolesis). These neutrophils typically localized near the megakaryocyte nucleus. By ultrastructural assessment, all internalized neutrophils remained morphologically intact. Most neutrophils resided within emperisomes, but some could be visualized exiting the emperisome to enter the cell cytoplasm. Neutrophils in the cytoplasm assumed close contact with the platelet-forming demarcation membrane system or the perinuclear endoplasmic reticulum. These findings reveal that megakaryocyte emperipolesis reflects at least 2 distinct processes differing in transit time and morphology, fast and slow emperipolesis, suggesting divergent physiologic functions.
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22
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O’Sullivan LR, Cahill MR, Young PW. The Importance of Alpha-Actinin Proteins in Platelet Formation and Function, and Their Causative Role in Congenital Macrothrombocytopenia. Int J Mol Sci 2021; 22:9363. [PMID: 34502272 PMCID: PMC8431150 DOI: 10.3390/ijms22179363] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2021] [Revised: 08/25/2021] [Accepted: 08/26/2021] [Indexed: 12/04/2022] Open
Abstract
The actin cytoskeleton plays a central role in platelet formation and function. Alpha-actinins (actinins) are actin filament crosslinking proteins that are prominently expressed in platelets and have been studied in relation to their role in platelet activation since the 1970s. However, within the past decade, several groups have described mutations in ACTN1/actinin-1 that cause congenital macrothrombocytopenia (CMTP)-accounting for approximately 5% of all cases of this condition. These findings are suggestive of potentially novel functions for actinins in platelet formation from megakaryocytes in the bone marrow and/or platelet maturation in circulation. Here, we review some recent insights into the well-known functions of actinins in platelet activation before considering possible roles for actinins in platelet formation that could explain their association with CMTP. We describe what is known about the consequences of CMTP-linked mutations on actinin-1 function at a molecular and cellular level and speculate how these changes might lead to the alterations in platelet count and morphology observed in CMTP patients. Finally, we outline some unanswered questions in this area and how they might be addressed in future studies.
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Affiliation(s)
- Leanne R. O’Sullivan
- School of Biochemistry & Cell Biology, University College Cork, T12 XF62 Cork, Ireland;
| | - Mary R. Cahill
- Department of Haematology and CancerResearch@UCC, Cork University Hospital, University College Cork, T12 XF62 Cork, Ireland;
| | - Paul W. Young
- School of Biochemistry & Cell Biology, University College Cork, T12 XF62 Cork, Ireland;
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23
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Mbiandjeu S, Balduini A, Malara A. Megakaryocyte Cytoskeletal Proteins in Platelet Biogenesis and Diseases. Thromb Haemost 2021; 122:666-678. [PMID: 34218430 DOI: 10.1055/s-0041-1731717] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
Abstract
Thrombopoiesis governs the formation of blood platelets in bone marrow by converting megakaryocytes into long, branched proplatelets on which individual platelets are assembled. The megakaryocyte cytoskeleton responds to multiple microenvironmental cues, including chemical and mechanical stimuli, sustaining the platelet shedding. During the megakaryocyte's life cycle, cytoskeletal networks organize cell shape and content, connect them physically and biochemically to the bone marrow vascular niche, and enable the release of platelets into the bloodstream. While the basic building blocks of the cytoskeleton have been studied extensively, new sets of cytoskeleton regulators have emerged as critical components of the dynamic protein network that supports platelet production. Understanding how the interaction of individual molecules of the cytoskeleton governs megakaryocyte behavior is essential to improve knowledge of platelet biogenesis and develop new therapeutic strategies for inherited thrombocytopenias caused by alterations in the cytoskeletal genes.
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Affiliation(s)
- Serge Mbiandjeu
- Department of Molecular Medicine, University of Pavia, Pavia, Italy
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24
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Chung J, Jeong D, Kim GH, Go S, Song J, Moon E, Huh YH, Kim D. Super-resolution imaging of platelet-activation process and its quantitative analysis. Sci Rep 2021; 11:10511. [PMID: 34006947 PMCID: PMC8131365 DOI: 10.1038/s41598-021-89799-9] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2020] [Accepted: 04/29/2021] [Indexed: 01/02/2023] Open
Abstract
Understanding the platelet activation molecular pathways by characterizing specific protein clusters within platelets is essential to identify the platelet activation state and improve the existing therapies for hemostatic disorders. Here, we employed various state-of-the-art super-resolution imaging and quantification methods to characterize the platelet spatiotemporal ultrastructural change during the activation process due to phorbol 12-myristate 13-acetate (PMA) stimuli by observing the cytoskeletal elements and various organelles at nanoscale, which cannot be done using conventional microscopy. Platelets could be spread out with the guidance of actin and microtubules, and most organelles were centralized probably due to the limited space of the peripheral thin regions or the close association with the open canalicular system (OCS). Among the centralized organelles, we provided evidence that granules are fused with the OCS to release their cargo through enlarged OCS. These findings highlight the concerted ultrastructural reorganization and relative arrangements of various organelles upon activation and call for a reassessment of previously unresolved complex and multi-factorial activation processes.
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Affiliation(s)
- Jinkyoung Chung
- Department of Chemistry, Hanyang University, Seoul, 04763, Republic of Korea
| | - Dokyung Jeong
- Department of Chemistry, Hanyang University, Seoul, 04763, Republic of Korea
| | - Geun-Ho Kim
- Department of Chemistry, Hanyang University, Seoul, 04763, Republic of Korea
| | - Seokran Go
- Department of Chemistry, Hanyang University, Seoul, 04763, Republic of Korea
| | - Jaewoo Song
- Department of Laboratory Medicine, Yonsei University College of Medicine, Seoul, 03722, Republic of Korea
| | - Eunyoung Moon
- Electron Microscopy Research Center, Korea Basic Science Institute, Cheongju, 28119, Republic of Korea
| | - Yang Hoon Huh
- Electron Microscopy Research Center, Korea Basic Science Institute, Cheongju, 28119, Republic of Korea
| | - Doory Kim
- Department of Chemistry, Hanyang University, Seoul, 04763, Republic of Korea.
- Research Institute for Convergence of Basic Sciences, Hanyang University, Seoul, 04763, Republic of Korea.
- Institute of Nano Science and Technology, Hanyang University, Seoul, 04763, Republic of Korea.
- Research Institute for Natural Sciences, Hanyang University, Seoul, 04763, Republic of Korea.
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25
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Heib T, Hermanns HM, Manukjan G, Englert M, Kusch C, Becker IC, Gerber A, Wackerbarth LM, Burkard P, Dandekar T, Balkenhol J, Jahn D, Beck S, Meub M, Dütting S, Stigloher C, Sauer M, Cherpokova D, Schulze H, Brakebusch C, Nieswandt B, Nagy Z, Pleines I. RhoA/Cdc42 signaling drives cytoplasmic maturation but not endomitosis in megakaryocytes. Cell Rep 2021; 35:109102. [PMID: 33979620 DOI: 10.1016/j.celrep.2021.109102] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2020] [Revised: 02/20/2021] [Accepted: 04/18/2021] [Indexed: 12/15/2022] Open
Abstract
Megakaryocytes (MKs), the precursors of blood platelets, are large, polyploid cells residing mainly in the bone marrow. We have previously shown that balanced signaling of the Rho GTPases RhoA and Cdc42 is critical for correct MK localization at bone marrow sinusoids in vivo. Using conditional RhoA/Cdc42 double-knockout (DKO) mice, we reveal here that RhoA/Cdc42 signaling is dispensable for the process of polyploidization in MKs but essential for cytoplasmic MK maturation. Proplatelet formation is virtually abrogated in the absence of RhoA/Cdc42 and leads to severe macrothrombocytopenia in DKO animals. The MK maturation defect is associated with downregulation of myosin light chain 2 (MLC2) and β1-tubulin, as well as an upregulation of LIM kinase 1 and cofilin-1 at both the mRNA and protein level and can be linked to impaired MKL1/SRF signaling. Our findings demonstrate that MK endomitosis and cytoplasmic maturation are separately regulated processes, and the latter is critically controlled by RhoA/Cdc42.
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Affiliation(s)
- Tobias Heib
- Institute of Experimental Biomedicine, University Hospital, University of Würzburg, 97080 Würzburg, Germany; Rudolf Virchow Center, University of Würzburg, 97080 Würzburg, Germany
| | - Heike M Hermanns
- Department of Internal Medicine II, Hepatology Research Laboratory, University Hospital Würzburg, 97080 Würzburg, Germany
| | - Georgi Manukjan
- Institute of Experimental Biomedicine, University Hospital, University of Würzburg, 97080 Würzburg, Germany; Rudolf Virchow Center, University of Würzburg, 97080 Würzburg, Germany
| | - Maximilian Englert
- Institute of Experimental Biomedicine, University Hospital, University of Würzburg, 97080 Würzburg, Germany; Rudolf Virchow Center, University of Würzburg, 97080 Würzburg, Germany
| | - Charly Kusch
- Institute of Experimental Biomedicine, University Hospital, University of Würzburg, 97080 Würzburg, Germany; Rudolf Virchow Center, University of Würzburg, 97080 Würzburg, Germany
| | - Isabelle Carlotta Becker
- Institute of Experimental Biomedicine, University Hospital, University of Würzburg, 97080 Würzburg, Germany; Rudolf Virchow Center, University of Würzburg, 97080 Würzburg, Germany
| | - Annika Gerber
- Institute of Experimental Biomedicine, University Hospital, University of Würzburg, 97080 Würzburg, Germany; Rudolf Virchow Center, University of Würzburg, 97080 Würzburg, Germany
| | - Lou Martha Wackerbarth
- Institute of Experimental Biomedicine, University Hospital, University of Würzburg, 97080 Würzburg, Germany; Rudolf Virchow Center, University of Würzburg, 97080 Würzburg, Germany
| | - Philipp Burkard
- Institute of Experimental Biomedicine, University Hospital, University of Würzburg, 97080 Würzburg, Germany; Rudolf Virchow Center, University of Würzburg, 97080 Würzburg, Germany
| | - Thomas Dandekar
- Department of Bioinformatics, Biocenter, University of Würzburg, 97074 Würzburg, Germany
| | - Johannes Balkenhol
- Department of Internal Medicine II, Hepatology Research Laboratory, University Hospital Würzburg, 97080 Würzburg, Germany; Department of Bioinformatics, Biocenter, University of Würzburg, 97074 Würzburg, Germany
| | - Daniel Jahn
- Department of Internal Medicine II, Hepatology Research Laboratory, University Hospital Würzburg, 97080 Würzburg, Germany
| | - Sarah Beck
- Institute of Experimental Biomedicine, University Hospital, University of Würzburg, 97080 Würzburg, Germany; Rudolf Virchow Center, University of Würzburg, 97080 Würzburg, Germany
| | - Mara Meub
- Department of Biotechnology and Biophysics, Biocenter, University of Würzburg, 97074 Würzburg, Germany
| | - Sebastian Dütting
- Institute of Experimental Biomedicine, University Hospital, University of Würzburg, 97080 Würzburg, Germany; Rudolf Virchow Center, University of Würzburg, 97080 Würzburg, Germany
| | - Christian Stigloher
- Imaging Core Facility, Biocenter, University of Würzburg, 97074 Würzburg, Germany
| | - Markus Sauer
- Department of Biotechnology and Biophysics, Biocenter, University of Würzburg, 97074 Würzburg, Germany
| | - Deya Cherpokova
- Institute of Experimental Biomedicine, University Hospital, University of Würzburg, 97080 Würzburg, Germany; Rudolf Virchow Center, University of Würzburg, 97080 Würzburg, Germany
| | - Harald Schulze
- Institute of Experimental Biomedicine, University Hospital, University of Würzburg, 97080 Würzburg, Germany; Rudolf Virchow Center, University of Würzburg, 97080 Würzburg, Germany
| | - Cord Brakebusch
- Biotech Research and Innovation Centre (BRIC), University of Copenhagen, 2200 Copenhagen, Denmark
| | - Bernhard Nieswandt
- Institute of Experimental Biomedicine, University Hospital, University of Würzburg, 97080 Würzburg, Germany; Rudolf Virchow Center, University of Würzburg, 97080 Würzburg, Germany.
| | - Zoltan Nagy
- Institute of Experimental Biomedicine, University Hospital, University of Würzburg, 97080 Würzburg, Germany; Rudolf Virchow Center, University of Würzburg, 97080 Würzburg, Germany
| | - Irina Pleines
- Institute of Experimental Biomedicine, University Hospital, University of Würzburg, 97080 Würzburg, Germany; Rudolf Virchow Center, University of Würzburg, 97080 Würzburg, Germany.
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26
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Abstract
One of the strategies used by cells to degrade and remodel the extracellular matrix (ECM) is based on invadosomes, actin-based force-producing cell–ECM contacts that function in adhesion and migration and are characterized by their capacity to mediate pericellular proteolysis of ECM components. Invadosomes found in normal cells are called podosomes, whereas invadosomes of invading cancer cells are named invadopodia. Despite their broad involvement in cell migration and in protease-dependent ECM remodeling and their detection in living organisms and in fresh tumor tissue specimens, the specific composition and dynamic behavior of podosomes and invadopodia and their functional relevance in vivo remain poorly understood. Here, we discuss recent findings that underline commonalities and peculiarities of podosome and invadopodia in terms of organization and function and propose an updated definition of these cellular protrusions, which are increasingly relevant in patho-physiological tissue remodeling.
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Affiliation(s)
- Alessandra Cambi
- Department of Cell Biology, Radboud Institute for Molecular Life Sciences, Radboud University Medical Center, Nijmegen, The Netherlands
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27
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Wagner N, Mott K, Upcin B, Stegner D, Schulze H, Ergün S. CXCL12-Abundant Reticular (CAR) Cells Direct Megakaryocyte Protrusions across the Bone Marrow Sinusoid Wall. Cells 2021; 10:722. [PMID: 33804965 PMCID: PMC8063926 DOI: 10.3390/cells10040722] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2021] [Revised: 03/16/2021] [Accepted: 03/22/2021] [Indexed: 11/17/2022] Open
Abstract
Megakaryocytes (MKs) release platelets into the lumen of bone marrow (BM) sinusoids while remaining to reside within the BM. The morphogenetic events of this complex process are still not fully understood. We combined confocal laser scanning microscopy with transmission and serial block-face scanning electron microscopy followed by 3D-reconstruction on mouse BM tissue sections. These analyses revealed that MKs in close vicinity to BM sinusoid (BMS) wall first induce the lateral retraction of CXCL12-abundant reticular (CAR) cells (CAR), followed by basal lamina (BL) degradation enabling direct MK-sinusoidal endothelial cells (SECs) interaction. Subsequently, an endothelial engulfment starts that contains a large MK protrusion. Then, MK protrusions penetrate the SEC, transmigrate into the BMS lumen and form proplatelets that are in direct contact to the SEC surface. Furthermore, such processes are induced on several sites, as observed by 3D reconstructions. Our data demonstrate that MKs in interaction with CAR-cells actively induce BMS wall alterations, including CAR-cell retraction, BL degradation, and SEC engulfment containing a large MK protrusion. This results in SEC penetration enabling the migration of MK protrusion into the BMS lumen where proplatelets that are adherent to the luminal SEC surface are formed and contribute to platelet release into the blood circulation.
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Affiliation(s)
- Nicole Wagner
- Institute of Anatomy and Cell Biology, Julius-Maximilians-University Würzburg, 97070 Würzburg, Germany; (N.W.); (B.U.)
| | - Kristina Mott
- Institute of Experimental Biomedicine, Chair I, University Hospital Würzburg, 97080 Würzburg, Germany; (K.M.); (D.S.)
| | - Berin Upcin
- Institute of Anatomy and Cell Biology, Julius-Maximilians-University Würzburg, 97070 Würzburg, Germany; (N.W.); (B.U.)
| | - David Stegner
- Institute of Experimental Biomedicine, Chair I, University Hospital Würzburg, 97080 Würzburg, Germany; (K.M.); (D.S.)
| | - Harald Schulze
- Institute of Experimental Biomedicine, Chair I, University Hospital Würzburg, 97080 Würzburg, Germany; (K.M.); (D.S.)
| | - Süleyman Ergün
- Institute of Anatomy and Cell Biology, Julius-Maximilians-University Würzburg, 97070 Würzburg, Germany; (N.W.); (B.U.)
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28
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Vainchenker W, Arkoun B, Basso-Valentina F, Lordier L, Debili N, Raslova H. Role of Rho-GTPases in megakaryopoiesis. Small GTPases 2021; 12:399-415. [PMID: 33570449 PMCID: PMC8583283 DOI: 10.1080/21541248.2021.1885134] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023] Open
Abstract
Megakaryocytes (MKs) are the bone marrow (BM) cells that generate blood platelets by a process that requires: i) polyploidization responsible for the increased MK size and ii) cytoplasmic organization leading to extension of long pseudopods, called proplatelets, through the endothelial barrier to allow platelet release into blood. Low level of localized RHOA activation prevents actomyosin accumulation at the cleavage furrow and participates in MK polyploidization. In the platelet production, RHOA and CDC42 play opposite, but complementary roles. RHOA inhibits both proplatelet formation and MK exit from BM, whereas CDC42 drives the development of the demarcation membranes and MK migration in BM. Moreover, the RhoA or Cdc42 MK specific knock-out in mice and the genetic alterations in their down-stream effectors in human induce a thrombocytopenia demonstrating their key roles in platelet production. A better knowledge of Rho-GTPase signalling is thus necessary to develop therapies for diseases associated with platelet production defects. Abbreviations: AKT: Protein Kinase BARHGEF2: Rho/Rac Guanine Nucleotide Exchange Factor 2ARP2/3: Actin related protein 2/3BM: Bone marrowCDC42: Cell division control protein 42 homologCFU-MK: Colony-forming-unit megakaryocyteCIP4: Cdc42-interacting protein 4mDIA: DiaphanousDIAPH1; Protein diaphanous homolog 1ECT2: Epithelial Cell Transforming Sequence 2FLNA: Filamin AGAP: GTPase-activating proteins or GTPase-accelerating proteinsGDI: GDP Dissociation InhibitorGEF: Guanine nucleotide exchange factorHDAC: Histone deacetylaseLIMK: LIM KinaseMAL: Megakaryoblastic leukaemiaMARCKS: Myristoylated alanine-rich C-kinase substrateMKL: Megakaryoblastic leukaemiaMLC: Myosin light chainMRTF: Myocardin Related Transcription FactorOTT: One-Twenty Two ProteinPACSIN2: Protein Kinase C And Casein Kinase Substrate In Neurons 2PAK: P21-Activated KinasePDK: Pyruvate Dehydrogenase kinasePI3K: Phosphoinositide 3-kinasePKC: Protein kinase CPTPRJ: Protein tyrosine phosphatase receptor type JRAC: Ras-related C3 botulinum toxin substrate 1RBM15: RNA Binding Motif Protein 15RHO: Ras homologousROCK: Rho-associated protein kinaseSCAR: Suppressor of cAMP receptorSRF: Serum response factorSRC: SarcTAZ: Transcriptional coactivator with PDZ motifTUBB1: Tubulin β1VEGF: Vascular endothelial growth factorWAS: Wiskott Aldrich syndromeWASP: Wiskott Aldrich syndrome proteinWAVE: WASP-family verprolin-homologous proteinWIP: WASP-interacting proteinYAP: Yes-associated protein
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Affiliation(s)
- William Vainchenker
- INSERM, UMR 1287, Gustave Roussy, Equipe Labellisée LNCC, Villejuif, France.,Université Paris Saclay, UMR 1287, Gustave Roussy, Villejuif, France.,Gustave Roussy, UMR 1287, Gustave Roussy, Villejuif, France.,GrEX, Sorbonne Paris Cité, Paris, France
| | - Brahim Arkoun
- INSERM, UMR 1287, Gustave Roussy, Equipe Labellisée LNCC, Villejuif, France.,Université Paris Saclay, UMR 1287, Gustave Roussy, Villejuif, France.,Gustave Roussy, UMR 1287, Gustave Roussy, Villejuif, France.,GrEX, Sorbonne Paris Cité, Paris, France
| | - Francesca Basso-Valentina
- INSERM, UMR 1287, Gustave Roussy, Equipe Labellisée LNCC, Villejuif, France.,Université Paris Saclay, UMR 1287, Gustave Roussy, Villejuif, France.,Gustave Roussy, UMR 1287, Gustave Roussy, Villejuif, France.,Université Sorbonne Paris Cité/Université Paris Dideront, Paris, France
| | - Larissa Lordier
- INSERM, UMR 1287, Gustave Roussy, Equipe Labellisée LNCC, Villejuif, France.,Université Paris Saclay, UMR 1287, Gustave Roussy, Villejuif, France.,Gustave Roussy, UMR 1287, Gustave Roussy, Villejuif, France
| | - Najet Debili
- INSERM, UMR 1287, Gustave Roussy, Equipe Labellisée LNCC, Villejuif, France.,Université Paris Saclay, UMR 1287, Gustave Roussy, Villejuif, France.,Gustave Roussy, UMR 1287, Gustave Roussy, Villejuif, France
| | - Hana Raslova
- INSERM, UMR 1287, Gustave Roussy, Equipe Labellisée LNCC, Villejuif, France.,Université Paris Saclay, UMR 1287, Gustave Roussy, Villejuif, France.,Gustave Roussy, UMR 1287, Gustave Roussy, Villejuif, France
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29
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Boscher J, Guinard I, Eckly A, Lanza F, Léon C. Blood platelet formation at a glance. J Cell Sci 2020; 133:133/20/jcs244731. [DOI: 10.1242/jcs.244731] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
ABSTRACT
The main function of blood platelets is to ensure hemostasis and prevent hemorrhages. The 1011 platelets needed daily are produced in a well-orchestrated process. However, this process is not yet fully understood and in vitro platelet production is still inefficient. Platelets are produced in the bone marrow by megakaryocytes, highly specialized precursor cells that extend cytoplasmic projections called proplatelets (PPTs) through the endothelial barrier of sinusoid vessels. In this Cell Science at a Glance article and the accompanying poster we discuss the mechanisms and pathways involved in megakaryopoiesis and platelet formation processes. We especially address the – still underestimated – role of the microenvironment of the bone marrow, and present recent findings on how PPT extension in vivo differs from that in vitro and entails different mechanisms. Finally, we recapitulate old but recently revisited evidence that – although bone marrow does produce megakaryocytes and PPTs – remodeling and the release of bona fide platelets, mainly occur in the downstream microcirculation.
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Affiliation(s)
- Julie Boscher
- Université de Strasbourg, INSERM, EFS Grand Est, BPPS UMR-S 1255, F-67000 Strasbourg, France
| | - Ines Guinard
- Université de Strasbourg, INSERM, EFS Grand Est, BPPS UMR-S 1255, F-67000 Strasbourg, France
| | - Anita Eckly
- Université de Strasbourg, INSERM, EFS Grand Est, BPPS UMR-S 1255, F-67000 Strasbourg, France
| | - François Lanza
- Université de Strasbourg, INSERM, EFS Grand Est, BPPS UMR-S 1255, F-67000 Strasbourg, France
| | - Catherine Léon
- Université de Strasbourg, INSERM, EFS Grand Est, BPPS UMR-S 1255, F-67000 Strasbourg, France
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