Investigation of the functional and structural role of podosomes in megakaryocytes

Q Science (General);R Medicine (General)

Schachtner, Hannah ; Machesky, L.M.

University:University of Glasgow

Department:Institute of Cancer Sciences

关键词: podosomes, cell adhesion, cell migration, megakaryocytes;   

Others  :  http://theses.gla.ac.uk/4032/1/2013schachtner1phd.pdf

来源: University of Glasgow

【 摘 要 】

Megakaryocytes (Mks) give rise to platelets via extension of proplatelet arms, which are released through the vascular sinusoids into the bloodstream. Mksand their precursors undergo varying interactions with the extracellular environment in the bone marrow during their maturation and positioning in the vascular niche. The dynamic remodeling of the actin cytoskeleton and the formation of cell -matrix contacts such as podosomes are fundamental for this process. However, the role and function of podosome structures in Mks are poorly understood.Podsomes are well characterized in different cell-types of the myeloid lineage such as macrophages and dendritic cells. Their formation is associated with a dynamic F-actin turnover, fascilitated cell migration and the degradation of extracellular matrix (ECM). Thefunction of podosome organellesis multifaceted and is described in association with cell adhesion, motility, ECM lysis, invasion and mechanosensors.A fundamental analysis of podosomes was necessary to define a potential function for these structures in Mks. I determined an abundant formation of classical podosomes with an F-actin core and a Vinculin ring in primary murine Mks, which were adherent on different physiological relevant ECM substrates such as fibrinogen, collagen I and a native basement membrane. Lifetime analysis was performed and was demonstrated to be dependent on the substrate as well as on Myosin-II activity. Another key feature of podosomes, the degradation of ECM proteins, could be detected and was mediated in an MMP associated manner. Furthermore, I verified that podosomesare necessary to penetrate a native basement membrane, which is amongst others part of blood vessels. IIIn this thesis I therefore demonstrate multifaceted properties of Mk podosomes and direct a potential function of these structures in the process of Mk maturation and possibly in platelet formation