Filamin A regulates caspase-3 cleavage in platelets in a protein kinase C (PKC)-dependent manner
Open Access
- 23 November 2022
- journal article
- research article
- Published by Portland Press Ltd. in Biochemical Journal
- Vol. 479 (22), 2351-2364
- https://doi.org/10.1042/bcj20220177
Abstract
Apoptosis is a critical process for the maintenance of cell populations, and involves mitochondrial depolarization, the sequential cleavage of caspase-9 and -3, followed by the externalization of phosphatidylserine (PS) on the plasma membrane. The actin cytoskeleton and its accessory proteins are known regulators of apoptotic signalling in nucleated cells but their roles in platelet apoptosis are undefined. Filamin A (FLNA) is a ubiquitously-expressed actin-crosslinking protein that also serves as an intracellular signalling scaffold. Here we used platelets from mice with a platelet-specific FLNA deficiency (Flnafl/Y, Pf4-cre/+, termed platelet-specific knockout) to test the role of FLNA in platelet apoptosis. Treatment with the BH3-mimetic drug ABT-737 induced caspase-3 cleavage and PS exposure in platelets from floxed mice (Flnafl/Y, termed control) but these effects were essentially abrogated in FLNA-null platelets (platelet-specific knockout). Protein kinase C (PKC), a known FLNA ligand, was also activated by ABT-737, and PKC’s phosphorylation of its downstream substrates was attenuated in FLNA-null platelets. The PKC inhibitor bisindolylmaleimide (BIM) also reduced caspase-3 cleavage, thus essentially phenocopying the FLNA-null platelets. Notably, the caspase-3 cleavage defect in FLNA-null platelets was rescued by the PKC-activating phorbol ester PMA, suggesting that FLNA and PKC share a common pathway in regulating platelet apoptosis. Mitochondrial depolarization and caspase-9 cleavage were unaffected by BIM treatment, suggesting that PKC specifically controls the downstream caspase-3 point of the pro-apoptotic signalling pathway. These data point to a novel role for FLNA in the regulation of platelet apoptosis, thus providing an improved understanding of how circulating platelet counts are maintained.This publication has 60 references indexed in Scilit:
- The actin cytoskeleton as a sensor and mediator of apoptosisBioArchitecture, 2012
- FlnA-null megakaryocytes prematurely release large and fragile platelets that circulate poorlyBlood, 2011
- BH3-only Activator Proteins Bid and Bim Are Dispensable for Bak/Bax-dependent Thrombocyte Apoptosis Induced by Bcl-xL DeficiencyOnline Journal of Public Health Informatics, 2011
- Oxidative stress and defective platelet apoptosis in naïve patients with Kawasaki diseaseBiochemical and Biophysical Research Communications, 2010
- Platelets Amplify Inflammation in Arthritis via Collagen-Dependent Microparticle ProductionScience, 2010
- Structural Basis of Protein Kinase C Isoform FunctionPhysiological Reviews, 2008
- Apoptosis: A Review of Programmed Cell DeathToxicologic Pathology, 2007
- The F-actin Cross-linking and Focal Adhesion Protein Filamin A Is a Ligand and in Vivo Substrate for Protein Kinase CαOnline Journal of Public Health Informatics, 2003
- Cell Death and Mechanoprotection by Filamin A in Connective Tissues after Challenge by Applied Tensile ForcesOnline Journal of Public Health Informatics, 2002
- The Role of Actin-binding Protein 280 in Integrin-dependent MechanoprotectionOnline Journal of Public Health Informatics, 1998