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.

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
• Journal: Journal Of Thrombosis And Haemostasis
• Print ISSN: 1538-7933
• 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
• Contract Date: Nov 13, 2014