Ischemic stroke is a significant disease that can lead to neurological deficits or death; however, only one pharmacological intervention drug is available and it predominately aims to eliminate the physical occlusion within the blood vessel. To explore potential therapeutic targets to improve recovery following an ischemic stroke, we began examining the role of Panx1 channels, which activate downstream purinergic receptors, within the cerebral vasculature. I have recently shown that deletion of endothelial Panx1 profoundly improves post-cerebral ischemia/reperfusion infarct volume. However, endothelial Panx1 could significant contribute to both arterial and venous endothelial functions. In this application, we demonstrate that arterial myogenic tone development (arterial), and inflammation of leukocytes following an ischemic stroke (venous), are significantly decreased in mice lacking endothelial Panx1. This application tests the hypothesis that endothelial Panx1 contributes to the development of ischemic stroke injury through both regulation of cerebral arterial myogenic tone and regulation of leukocyte adhesion and emigration in cerebral venous endothelial cells. Our preliminary data suggest that Panx1 activation during myogenic tone development is regulated through interaction with b3 integrins. Whereas, in cerebral veins, I find leukocyte adhesion in cerebral venules following an ischemic stroke is regulated through Panx1 channel function. These studies will provide insight into the differential roles and regulation of Panx1 within arterial and venous cerebral endothelial cells, their contribution to the etiology of ischemic stroke injury, and lay the foundation for future identification of therapeutic interventions for ischemic stroke patients. During the mentored phase of this application, I will develop novel transgenic mice to evaluate the overexpression of endothelial Panx1 and obtain necessary skills to evaluate the functional consequence of Panx1-b3 interaction and image cerebral inflammation following an ischemic stroke using in vivo intravital microscopy techniques. I will continue my professional and scientific development in preparation for the independent phase with continuous guidance from my mentoring committee. During the independent phase, I will develop a novel transgenic mouse that will delete or overexpress Panx1 specifically within arterial endothelial cells and determine the role of arterial verse venous endothelial Panx1 during an ischemic stroke. In addition, I will establish the downstream purinergic signaling involved in Panx1-dependent leukocyte adhesion, by in vivo imaging of cerebral venules, and emigration, using flow cytometry, and its impact of determining the severity of an ischemic stroke. This project will foster my continued scientific and professional training and facilitate my establishing an independent research program in academia.
Ischemic stroke remains a leading cause of morbidity and mortality in the US; however, there is only one approved drug treatment available, which does not target improving post-reperfusion injury. The arterial and venous cerebral vasculature play important functions, blood flow regulation via myogenic reactivity and post- injury inflammation, respectively, during and following an ischemic injury. This proposal aims to evaluate the role and regulation of Pannexin 1, a potential novel therapeutic target, within arterial and venous cerebral endothelial cells and how these contribute to the etiology of ischemic stroke.
