G‐protein coupled receptor kinases’ (GRKs) role in APC/PAR1‐induced endothelial cells

Abstract

Endothelial dysfunction is a hallmark of inflammation and prevalent in vascular diseases. Recent efforts are focused on developing new strategies to enhance endothelial resistance to inflammation. One promising candidate is activated Protein C (APC), which has been shown in preclinical studies to increase endothelial barrier protection and reduce inflammatory responses. APC enhances endothelial cytoprotection by activation of PAR1 through cleavage at an N‐terminal arginine (R)‐46 site, that is distinct from the canonical thrombin cleavage site at R‐41. This results in the generation of a distinct tethered ligand that promotes PAR1 bias signaling. G‐protein coupled receptor kinase (GRK) family plays a role in phosphorylating PAR1 and recruiting b‐arrestins, however, the contribution of GRKs to b‐arrestin driven cytoprotection is unknown. Our study focuses on determining the role and mechanisms by which GRKs regulate APC/PAR1‐induced endothelial cytoprotection to delineate their function in this pathway. Here we will present studies examining the function and mechanism by which GRKs regulate endothelial cytoprotective responses using GRK‐specific siRNA to assess function as well as confocal immunofluorescence imaging and biochemical sucrose fraction to examine GRK localization and compartmentalization in caveolae. The work is expected to provide important new insight into the role of GRKs in regulating APC/PAR1 cytoprotection in human cultured endothelial cells.Support or Funding InformationThis work is funded by NIH R01 GM090689, NIH R35GM127121, and IRACDA K12 GM068524.