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Becker IC, Wilkie AR, Unger BA, Sciaudone AR, Fatima F, Tsai IT, Xu K, Machlus KR, Italiano JE. Dynamic actin/septin network in megakaryocytes coordinates proplatelet elaboration. Haematologica 2024; 109:915-928. [PMID: 37675512 PMCID: PMC10905084 DOI: 10.3324/haematol.2023.283369] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2023] [Accepted: 08/18/2023] [Indexed: 09/08/2023] Open
Abstract
Megakaryocytes (MK) undergo extensive cytoskeletal rearrangements as they give rise to platelets. While cortical microtubule sliding has been implicated in proplatelet formation, the role of the actin cytoskeleton in proplatelet elongation is less understood. It is assumed that actin filament reorganization is important for platelet generation given that mouse models with mutations in actin-associated proteins exhibit thrombocytopenia. However, due to the essential role of the actin network during MK development, a differential understanding of the contribution of the actin cytoskeleton on proplatelet release is lacking. Here, we reveal that inhibition of actin polymerization impairs the formation of elaborate proplatelets by hampering proplatelet extension and bead formation along the proplatelet shaft, which was mostly independent of changes in cortical microtubule sliding. We identify Cdc42 and its downstream effectors, septins, as critical regulators of intracellular actin dynamics in MK, inhibition of which, similarly to inhibition of actin polymerization, impairs proplatelet movement and beading. Super-resolution microscopy revealed a differential association of distinctive septins with the actin and microtubule cytoskeleton, respectively, which was disrupted upon septin inhibition and diminished intracellular filamentous actin dynamics. In vivo, septins, similarly to F-actin, were subject to changes in expression upon enforcing proplatelet formation through prior platelet depletion. In summary, we demonstrate that a Cdc42/septin axis is not only important for MK maturation and polarization, but is further required for intracellular actin dynamics during proplatelet formation.
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Affiliation(s)
- Isabelle C Becker
- Vascular Biology Program, Boston Children's Hospital, 1 Blackfan Circle, Boston, MA, 02115; Department of Surgery, Harvard Medical School, 25 Shattuck Street, Boston, MA 02115
| | - Adrian R Wilkie
- Vascular Biology Program, Boston Children's Hospital, 1 Blackfan Circle, Boston, MA, 02115; Department of Surgery, Harvard Medical School, 25 Shattuck Street, Boston, MA 02115
| | - Bret A Unger
- Department of Chemistry, University of California, Berkeley, Berkeley, CA, 94720
| | | | - Farheen Fatima
- Vascular Biology Program, Boston Children's Hospital, 1 Blackfan Circle, Boston, MA, 02115; Department of Surgery, Harvard Medical School, 25 Shattuck Street, Boston, MA 02115
| | - I-Ting Tsai
- Vascular Biology Program, Boston Children's Hospital, 1 Blackfan Circle, Boston, MA, 02115; Department of Surgery, Harvard Medical School, 25 Shattuck Street, Boston, MA 02115
| | - Ke Xu
- Department of Chemistry, University of California, Berkeley, Berkeley, CA, 94720
| | - Kellie R Machlus
- Vascular Biology Program, Boston Children's Hospital, 1 Blackfan Circle, Boston, MA, 02115; Department of Surgery, Harvard Medical School, 25 Shattuck Street, Boston, MA 02115
| | - Joseph E Italiano
- Vascular Biology Program, Boston Children's Hospital, 1 Blackfan Circle, Boston, MA, 02115; Department of Surgery, Harvard Medical School, 25 Shattuck Street, Boston, MA 02115.
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Cloos AS, Pollet H, Stommen A, Maja M, Lingurski M, Brichard B, Lambert C, Henriet P, Pierreux C, Pyr dit Ruys S, Van Der Smissen P, Vikkula M, Gatto L, Martin M, Brouillard P, Vertommen D, Tyteca D. Splenectomy improves erythrocyte functionality in spherocytosis based on septin abundance, but not maturation defects. Blood Adv 2023; 7:4705-4720. [PMID: 36753606 PMCID: PMC10468371 DOI: 10.1182/bloodadvances.2022009114] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2022] [Revised: 12/30/2022] [Accepted: 01/13/2023] [Indexed: 02/10/2023] Open
Abstract
Splenectomy improves the clinical parameters of patients with hereditary spherocytosis, but its potential benefit to red blood cell (RBC) functionality and the mechanism behind this benefit remain largely overlooked. Here, we compared 7 nonsplenectomized and 13 splenectomized patients with mutations in the β-spectrin or the ankyrin gene. We showed that hematological parameters, spherocyte abundance, osmotic fragility, intracellular calcium, and extracellular vesicle release were largely but not completely restored by splenectomy, whereas cryohemolysis was not. Affected RBCs exhibited decreases in β-spectrin and/or ankyrin contents and slight alterations in spectrin membrane distribution, depending on the mutation. These modifications were found in both splenectomized and nonsplenectomized patients and poorly correlated with RBC functionality alteration, suggesting additional impairments. Accordingly, we found an increased abundance of septins, small guanosine triphosphate-binding cytoskeletal proteins. Septins-2, -7, and -8 but not -11 were less abundant upon splenectomy and correlated with the disease severity. Septin-2 membrane association was confirmed by immunolabeling. Except for cryohemolysis, all parameters of RBC morphology and functionality correlated with septin abundance. The increased septin content might result from RBC maturation defects, as evidenced by (1) the decreased protein 4.2 and Rh-associated glycoprotein content in all patient RBCs, (2) increased endoplasmic reticulum remnants and endocytosis proteins in nonsplenectomized patients, and (3) increased lysosomal and mitochondrial remnants in splenectomized patients. Our study paves the way for a better understanding of the involvement of septins in RBC membrane biophysical properties. In addition, the lack of restoration of septin-independent cryohemolysis by splenectomy may call into question its recommendation in specific cases.
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Affiliation(s)
- Anne-Sophie Cloos
- CELL Unit & PICT Imaging Platform, de Duve Institute, UCLouvain, Brussels, Belgium
| | - Hélène Pollet
- CELL Unit & PICT Imaging Platform, de Duve Institute, UCLouvain, Brussels, Belgium
| | - Amaury Stommen
- CELL Unit & PICT Imaging Platform, de Duve Institute, UCLouvain, Brussels, Belgium
| | - Mauriane Maja
- CELL Unit & PICT Imaging Platform, de Duve Institute, UCLouvain, Brussels, Belgium
| | - Maxime Lingurski
- CELL Unit & PICT Imaging Platform, de Duve Institute, UCLouvain, Brussels, Belgium
| | - Bénédicte Brichard
- Pediatric Hematology & Oncology Unit, Saint-Luc Hospital, UCLouvain, Brussels, Belgium
| | | | - Patrick Henriet
- CELL Unit & PICT Imaging Platform, de Duve Institute, UCLouvain, Brussels, Belgium
| | - Christophe Pierreux
- CELL Unit & PICT Imaging Platform, de Duve Institute, UCLouvain, Brussels, Belgium
| | - Sébastien Pyr dit Ruys
- PHOS Unit & MASSPROT Proteomics Platform, de Duve Institute, UCLouvain, Brussels, Belgium
| | | | - Miikka Vikkula
- Human Molecular Genetics Unit, de Duve Institute, UCLouvain, Brussels, Belgium
| | - Laurent Gatto
- Computational Biology and Bioinformatics Unit, de Duve Institute, UCLouvain, Brussels, Belgium
| | - Manon Martin
- Computational Biology and Bioinformatics Unit, de Duve Institute, UCLouvain, Brussels, Belgium
| | - Pascal Brouillard
- Human Molecular Genetics Unit, de Duve Institute, UCLouvain, Brussels, Belgium
| | - Didier Vertommen
- PHOS Unit & MASSPROT Proteomics Platform, de Duve Institute, UCLouvain, Brussels, Belgium
| | - Donatienne Tyteca
- CELL Unit & PICT Imaging Platform, de Duve Institute, UCLouvain, Brussels, Belgium
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Benoit B, Poüs C, Baillet A. Septins as membrane influencers: direct play or in association with other cytoskeleton partners. Front Cell Dev Biol 2023; 11:1112319. [PMID: 36875762 PMCID: PMC9982393 DOI: 10.3389/fcell.2023.1112319] [Citation(s) in RCA: 7] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2022] [Accepted: 01/23/2023] [Indexed: 02/19/2023] Open
Abstract
The cytoskeleton comprises three polymerizing structures that have been studied for a long time, actin microfilaments, microtubules and intermediate filaments, plus more recently investigated dynamic assemblies like septins or the endocytic-sorting complex required for transport (ESCRT) complex. These filament-forming proteins control several cell functions through crosstalks with each other and with membranes. In this review, we report recent works that address how septins bind to membranes, and influence their shaping, organization, properties and functions, either by binding to them directly or indirectly through other cytoskeleton elements.
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Affiliation(s)
- Béatrice Benoit
- INSERM UMR-S 1193, UFR de Pharmacie, University Paris-Saclay, Orsay, France
| | - Christian Poüs
- INSERM UMR-S 1193, UFR de Pharmacie, University Paris-Saclay, Orsay, France.,Laboratoire de Biochimie-Hormonologie, Hôpital Antoine Béclère, AP-HP, Hôpitaux Universitaires Paris-Saclay, Clamart, France
| | - Anita Baillet
- INSERM UMR-S 1193, UFR de Pharmacie, University Paris-Saclay, Orsay, France
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Minor Kinases with Major Roles in Cytokinesis Regulation. Cells 2022; 11:cells11223639. [PMID: 36429067 PMCID: PMC9688779 DOI: 10.3390/cells11223639] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2022] [Revised: 11/07/2022] [Accepted: 11/14/2022] [Indexed: 11/18/2022] Open
Abstract
Cytokinesis, the conclusive act of cell division, allows cytoplasmic organelles and chromosomes to be faithfully partitioned between two daughter cells. In animal organisms, its accurate regulation is a fundamental task for normal development and for preventing aneuploidy. Cytokinesis failures produce genetically unstable tetraploid cells and ultimately result in chromosome instability, a hallmark of cancer cells. In animal cells, the assembly and constriction of an actomyosin ring drive cleavage furrow ingression, resulting in the formation of a cytoplasmic intercellular bridge, which is severed during abscission, the final event of cytokinesis. Kinase-mediated phosphorylation is a crucial process to orchestrate the spatio-temporal regulation of the different stages of cytokinesis. Several kinases have been described in the literature, such as cyclin-dependent kinase, polo-like kinase 1, and Aurora B, regulating both furrow ingression and/or abscission. However, others exist, with well-established roles in cell-cycle progression but whose specific role in cytokinesis has been poorly investigated, leading to considering these kinases as "minor" actors in this process. Yet, they deserve additional attention, as they might disclose unexpected routes of cell division regulation. Here, we summarize the role of multifunctional kinases in cytokinesis with a special focus on those with a still scarcely defined function during cell cleavage. Moreover, we discuss their implication in cancer.
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