Deletion of the Arp2/3 complex in megakaryocytes leads to microthrombocytopenia in mice

David S Paul; Caterina Casari; Congying Wu; Raymond Piatt; Swetha Pasala; Robert A Campbell; Kathryn O Poe; Dorsaf Ghalloussi; Robert H Lee; Jeremy D Rotty; Brian C Cooley; Kellie R Machlus; Joseph E Italiano Jr; Andrew S Weyrich; James E Bear; Wolfgang Bergmeier

doi:10.1182/bloodadvances.2017006973

Deletion of the Arp2/3 complex in megakaryocytes leads to microthrombocytopenia in mice

Blood Adv. 2017 Aug 8;1(18):1398-1408. doi: 10.1182/bloodadvances.2017006973.

Authors

David S Paul¹, Caterina Casari¹, Congying Wu^{2

3}, Raymond Piatt¹, Swetha Pasala⁴, Robert A Campbell⁵, Kathryn O Poe¹, Dorsaf Ghalloussi¹, Robert H Lee¹, Jeremy D Rotty^{2

3}, Brian C Cooley⁶, Kellie R Machlus⁷, Joseph E Italiano Jr^{7

8}, Andrew S Weyrich⁵, James E Bear^{2

3}, Wolfgang Bergmeier^{1

4}

Affiliations

¹ McAllister Heart Institute, University of North Carolina at Chapel Hill (NC), USA.
² UNC Lineberger Comprehensive Cancer Center, University of North Carolina at Chapel Hill (NC), USA.
³ Department of Cell Biology and Physiology, University of North Carolina at Chapel Hill (NC), USA.
⁴ Department of Biochemistry and Biophysics, University of North Carolina at Chapel Hill (NC), USA.
⁵ Program in Molecular Medicine and Department of Internal Medicine, University of Utah, Salt Lake City (UT), USA.
⁶ Rodent Advanced Surgical Core, University of North Carolina at Chapel Hill (NC), USA.
⁷ Division of Hematology, Department of Medicine; Brigham and Women's Hospital and Harvard Medical School; Boston, MA, USA.
⁸ Vascular Biology Program, Department of Surgery; Children's Hospital Boston; Boston, MA, USA.

Abstract

Actin reorganization regulates key processes in platelet activation. Here we examined the role of the Arp2/3 complex, an essential component in actin filament branching, in platelet function. The Arpc2 gene, encoding the p34 subunit of the Arp2/3 complex, was deleted in the megakaryocyte lineage (Arpc2^fl/flPF4-Cre). Deletion of the Arp2/3 complex resulted in marked microthrombocytopenia in mice, caused by premature platelet release into the bone marrow compartment and impaired platelet survival in circulation. Arpc2^fl/flPF4-Cre platelets exhibited alterations in their actin cytoskeleton and their peripheral microtubule coil. Thrombocytopenia was alleviated following clodronate liposome-induced macrophage depletion in Arpc2^fl/flPF4-Cre mice. Arpc2^fl/flPF4-Cre platelets failed to spread and showed a mild defect in integrin activation and aggregation. However, no significant differences in hemostasis or thrombosis were observed between Arpc2^fl/flPF4-Cre and control mice. Thus, Arp2/3 is critical for platelet homeostasis but plays only a minor role for vascular hemostasis.

Abstract

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