Role of Protease‐activated receptors in Activated protein C‐mediated anti‐inflammatory responses in endothelial cells

Abstract

Endothelial dysfunction is a hallmark of inflammation is and associated with the pathogenesis of vascular diseases induced by infections, oxidative stress or mechanical stress. This results in endothelial cell activation, disruption of endothelial barrier function, sensitivity to apoptosis and organ failure. While there are very limited options for treating diseases associated with endothelial dysfunction (e.g. sepsis, cardiovascular diseases), Activated protein C (APC) has shown pharmacological benefits in various preclinical settings. APC mediates multiple cytoprotective effects including 1) anti‐inflammatory responses, 2) stabilization of the endothelial barrier, and 3) anti‐apoptotic responses. Protease‐activated receptor‐1 (PAR1), a G protein‐coupled receptor (GPCR), is the central mediator of APC cellular signaling. However, there is limited understanding of the signaling pathways by which APC/PAR1 and APC/PAR1/PAR3 promote endothelial anti‐inflammatory responses. The long‐term goal of these studies is to understand the pathways by which the endothelium can resist inflammation and disruption to facilitate the advancement of new targets for therapeutic development. The subsequent studies aim to provide key mechanistic insight into how PAR1 and PAR3 drive endothelial anti‐inflammatory responses. Endothelial cytoprotection is driven by APC activation of PAR1 through cleavage at an N‐terminal arginine (R)‐46 site, that is distinct from the canonical thrombin cleavage site at R41. This results in the generation of a tethered ligand that promotes PAR1 biased signaling. We hypothesize that different co‐receptors including PAR3 and S1PR1 distinctly regulate specific APC/PAR1 anti‐inflammatory responses by influencing distinct beta‐arrestin signaling pathways. Here, we will examine the requirement of PAR1, co‐receptors PAR3 and S1PR1, and beta‐arrestin adaptor proteins to modulate APC‐mediated inhibition of TNF‐alpha pro‐inflammatory signaling in endothelial cells. Other studies aimed at elucidating additional mechanisms of APC‐mediated anti‐inflammatory responses, including post‐transcriptional control of pro‐inflammatory genes.Support or Funding InformationBurroughs Welcome Fund: Post Doctoral Enrichment Program awardNIH/NHLB T32 Cardiovascular Physiology and Pharmacology Training Grant ‐NIGMSR01GM116597 (Trejo)