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Identification of a novel, actin-rich structure, the actin nodule, in the early stages of platelet spreading

Calaminus, S. D. J.; Calaminus, Simon D J; Thomas, S.; McCarty, O. J. T.; Machesky, L. M.; McCarty, O. J T; Watson, S. P.

Authors

S. D. J. Calaminus

S. Thomas

O. J. T. McCarty

L. M. Machesky

O. J T McCarty

S. P. Watson



Abstract

During platelet spreading, the actin cytoskeleton undergoes marked changes, forming filopodia, lamellipodia and stress fibres. In the present study, we report the identification of a novel actin-rich structure, termed an actin nodule, which appears prior to lamellipodia and stress fibre formation. Methods: Platelet spreading was monitored using human platelets and mouse GFP-actin platelets using real-time and end-point DIC, and fluorescent and electron microscopy (EM). Results: We identified a small, novel actin structure, the actin nodule, in the early stages of adhesion and spreading, which we hypothesize to be a precursor of lamellipodia and stress fibres. Nodule formation shows an inverse correlation to Rho kinase and myosin-II activity, is independent of PI3-kinase, but dependent on Src kinase activity. Actin nodules contain multiple proteins, including Arp2/3, Fyn, Rac, and β1- and β3- integrins, but not Src. EM analysis revealed that actin filaments extend in all directions from the nodules. Actin nodules are present on multiple matrices, including fibrinogen, laminin and VWF+botrocetin. Conclusion: This work identifies a novel platelet actin structure, which we propose is a precursor to both lamellipodia and stress fibres and acts to drive platelet spreading.

Citation

Calaminus, S. D. J., Thomas, S., McCarty, O. J. T., Machesky, L. M., & Watson, S. P. (2008). Identification of a novel, actin-rich structure, the actin nodule, in the early stages of platelet spreading. Journal of thrombosis and haemostasis : JTH, 6(11), 1944-1952. https://doi.org/10.1111/j.1538-7836.2008.03141.x

Journal Article Type Article
Publication Date Oct 24, 2008
Deposit Date Nov 13, 2014
Publicly Available Date Mar 29, 2024
Journal Journal Of Thrombosis And Haemostasis
Print ISSN 1538-7933
Electronic ISSN 1538-7836
Publisher Wiley
Peer Reviewed Peer Reviewed
Volume 6
Issue 11
Pages 1944-1952
DOI https://doi.org/10.1111/j.1538-7836.2008.03141.x
Keywords actin, cytoskeleton, Arp2/3, platelet spreading, Rho kinase, Src kinases,
Public URL https://hull-repository.worktribe.com/output/469026