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Phospholipase D is a central regulator of collagen I‐induced cytoskeletal rearrangement and podosome formation in megakaryocytes
Author(s) -
Stritt S.,
Thielmann I.,
Dütting S.,
Stegner D.,
Nieswandt B.
Publication year - 2014
Publication title -
journal of thrombosis and haemostasis
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.947
H-Index - 178
eISSN - 1538-7836
pISSN - 1538-7933
DOI - 10.1111/jth.12623
Subject(s) - podosome , microbiology and biotechnology , platelet , phospholipase d , actin , cytoskeleton , cytoplasm , biology , chemistry , cell , immunology , signal transduction , biochemistry
Summary Background Blood platelets are small anucleated cell fragments generated from bone marrow megakaryocytes ( MK s) by a cytoskeleton‐driven process. Thereby, mature MK s form long cytoplasmic protrusions (pro‐platelets), which extend into the sinusoids within the bone marrow and finally release platelets. Podosomes are F‐actin rich matrix contacts that have been suggested to play an important role in cell migration, but also in pro‐platelet formation by MK s. Phospholipase D ( PLD ) has been proposed to contribute to the regulation of actin dynamics through the local generation of phosphatidic acid but its role in platelet formation is unknown. Objective We sought to investigate the significance of PLD in MK podosome formation and thrombocytopoiesis. Methods Podosome formation, spreading and ultra‐structure of PLD single‐ and double‐deficient MK s were analyzed using confocal and transmission electron microscopy. Results Phospholipase D‐deficient MK s displayed a highly altered ultra‐structure in vivo and abnormal actin rearrangement, with almost abolished formation of podosomes upon spreading on collagen I in vitro . However, MK endomitosis and platelet production were not altered by PLD deficiency. Conclusion Together, our findings point to a specific function of PLD in actin dynamics as well as podosome formation and size determination in MK s on a collagen I matrix. The normal platelet number in PLD ‐deficient mice, however, suggests the existence of compensatory mechanisms in vivo that overcome the defective podosome formation observed in vitro .