1. Hematopoiesis II JC Kostyak 10-22-09

3. Megakaryocytes Must Migrate When Ready to Produce Platelets SDF-1 CXCR4 Stromal Cells

5. Migration Through the Basement Membrane Bone Sinusoidal Vessel Endothelial Cells MMP

6. Megakaryocyte Docking ? PECAM-1 ? MK MK Once the Mk has docked, it can begin to produce proplatelet processes ?

7. Is PECAM-1 Required for MK Docking? Dhanjal et al., Blood 2007

8. Once Docked MKs Produce Proplatelets Patel et al., JCI 2005

9. Microtubule Elongation MT form long extensions which bend and branch MT line the membrane of the newly formed platelet In order to branch MT must elongate, then fold (B) and extend due to sliding (C). This bending allows the MT to form the next platelet (as seen above). Patel et al., JCI 2005

10. MT Review Conde and Cesares, Nature 2009

11. Microtubule Sliding www.Stanford.edu Mitotic Kinesin Small molecular motors use ATP

12. Kinesins and Dynein V Kinesin Retrograde MTOC Anterograde + - + - Retrograde Dynein There are many examples of each! V

13. Proplatelet Formation Originates Opposite the Nucleus Italiano et al., JCB 1999

14. The Theatrical Version

15. Kinesins Localize in the Cytosol while Dynein is Localized to the Proplatelets Patel et al., Blood 2005

16. Proplatelets Extend into BM Sinusoidal Vessels PI = Circulating platelet, BI = Bulbous tip, Er = Erythrocyte, MP = Proplatelet, SW = Sinusoidal vessel Kessel and Kardon, Tissues and Organs 1979

21. In Vivo Biotinylation to Track Platelet Clearance NH 2 Sulfo-NHS-Biotin + +

22. IVB Procedure Tail vein injection of biotin Collect blood sample (~5ul) at various times beginning 1 hr after injection Stain with streptavidin and Thiazole Orange and analyze by flow cytometry

24. Platelet Related Disorders