Molecular mechanisms regulating Proteinase-Activated Receptors (PARs)

Proteinase-activated receptors (PARs) are a four-member family of G protein-coupled receptors defined by their irreversible proteolytic mechanism of activation. PARs have emerged as important regulators of various physiological responses and are implicated in numerous pathological conditions. Importantly, PAR1 and PAR4 are critical regulators of platelet function, while PAR2 is well established as a driver of inflammatory responses. PAR-targeted drug development efforts are therefore of great interest. In this review, we provide an overview of recent advances in our understanding of molecular mechanisms underlying PAR activation, effector interaction, and signaling. We also provide an overview of the diverse proteolytic enzymes that are now established as PAR regulators and describe the ability of different enzymes to elicit biased signaling through PARs. Finally, we highlight recent advances in the development of PAR-targeted pharmacological agents and discuss recent structure-activity relationship studies.