Studies on the role of cytoskeletal proteins in megakaryo- and thrombopoiesis

• Applicant: Professor Dr. Markus Bender
• Subject Area: Cell Biology
• Term: from 2012 to 2014
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 217885151

At sites of vascular injury, blood platelets come into contact with exposed thrombogenic subendothelial components, and form a plug to prevent excessive blood loss. The mechanisms orchestrating the complex process by which the platelet precursor cells in the bone marrow, the megakaryocytes (MKs), form and release platelets are still poorly understood. Mature MKs generate long cytoplasmic extensions, termed proplatelets, which have the capacity to generate platelets in the blood circulation. Cytoskeletal proteins have been shown to be critically involved in the process of platelet production. In this project, two important aspects of thrombopoiesis will be addressed: (1) The actin-binding protein filamin A (FLNa), a scaffold protein with multiple binding partners, is crucial for normal MK maturation and platelet function. However, the involvement of FLNa binding partners in this process has remained elusive. Thus, lethally irradiated mice will be analysed after adaptive transfer of MKs carrying point mutations in defined binding sites of FLNa to determine their role in platelet production. (2) Glycosidases and glycotransferases regulate at least in part the life span of platelets. How these proteins are specifically packaged, transported, and finally released after platelet activation or storage is not understood. A better understanding of these processes is however required for the development of new strategies for the treatment of thrombocytopenic patients and to overcome current problems in blood banking. To address this experimentally, fluorescently tagged versions of these proteins will be expressed in MKs in vitro and their packaging in MK and proplatelets as well as their upregulation in isolated platelets will be visualized in realtime. Furthermore, the use of specific inhibitors or "knockdown" approaches will provide deeper insights into these processes.

• DFG Programme: Research Fellowships
• International Connection: USA
• Host: Professor Dr. John H. Hartwig