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Title: Mechanisms of shear stress sensing in the vasculature
Author: Gaunt, Hannah Jane
ISNI:       0000 0004 7654 8865
Awarding Body: University of Leeds
Current Institution: University of Leeds
Date of Award: 2018
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Background: Cardiovascular disease is usually associated with endothelial dysfunction. One characteristic of endothelial dysfunction is the lack of nitric oxide production and shear stress is an important contributing factor. Endothelial cells are exposed to the frictional force evoked by the flow of blood. Mechanotransduction of shear stress plays key roles in cardiovascular physiology and pathophysiology and is important in maintaining endothelial cell function. The mechanosensitive non-selective cation channel, Piezo1, is reported to be a direct sensor of shear stress in endothelial cells promoting their alignment, vascular development and as a sensor of whole body physical activity. Activation of Piezo1 by Yoda1 was sought to investigate the mechanism coupling Piezo1 to S1177 endothelial nitric oxide synthase (eNOS) phosphorylation. Methods and Results: Data indicate that the chemical activator of Piezo1, Yoda1, is a useful research tool, not only mimicking mechanical stimulation of the channels but also facilitating study of Piezo1 channels without the need for mechanical stimulation. In human umbilical vein endothelial cells (HUVECs) eNOS was found to be rapidly phosphorylated predominantly at the key activating serine residue 1177/1179 by Yoda1 application independently of ATP and P2Y2 receptors. Instead, Fyn kinase and PKCd are required for the integrity of this response without affecting Yoda1- or hypotonicityevoked Ca2+ signals. Furthermore, the data suggest that Piezo1 somehow cross talks with CD31 and VE-Cadherin proteins of the mechanosensory triad to evoke eNOS phosphorylation. Over-expression studies using two independent methods for detecting protein-protein interaction provided evidence that Piezo1 is capable of interacting with CD31. Conclusion: The data indicate the existence of direct coupling between Piezo1 and eNOS phosphorylation and that Fyn kinase and PKCd are important mediators of this response. Furthermore, an important partnership between Piezo1 and CD31 and VE-Cadherin, key members of the mechanosensitive triad, was determined. Understanding Piezo1 partner proteins and signalling could be important for achieving better appreciation of how shear stress regulates cardiovascular structure and function.
Supervisor: Beech, David J. Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available