Abstract
Protease-activated receptor 1 (PAR1), a G protein-coupled receptor (GPCR), is irreversibly activated upon thrombin cleavage, then internalized via clathrin-coated pit into the cells and degraded in lysosome. This mechanism is critical for the termination of PAR1 signaling. However, the exact mechanism by which PAR1 is internalized and sorted to lysosome is poorly understood. Many studies show that β-arrestin contributes to the desensitization of many activated GPCRs by uncoupling the signal transduction process and mediates the endocytosis of many activated GPCRs. In this thesis, I investigated whether β-arrestin is involved in regulating the intracellular trafficking of PAR1. I found that β-arrestin was rapidly recruited to cell membrane and colocalized with activated PAR1 after agonist stimulation. Then, β-arrestin was sorted together with PAR1 into early endosomes. In addition, the dominant-negative form of β-arrestin (β-arr319-418) blocked agonist-stimulated internalization of PAR1. These results indicate that β-arrestin is involved in regulating the intracellular trafficking of PAR1 by associating with activated receptor into early endosomes.