ß-arrestins and G protein-coupled receptor kinases in viral entry: A graphical review.

Viruses rely on host-cell machinery in order to invade host cells and carry out a successful infection. G-protein coupled receptor (GPCR)-mediated signaling pathways are master regulators of cellular physiological processing and are an attractive target for viruses to rewire cells during infection. In particular, the GPCR-associated scaffolding proteins ß-arrestins and GPCR signaling effectors G-protein receptor kinases (GRKs) have been identified as key cellular factors that mediate viral entry and orchestrate signaling pathways that reprogram cells for viral replication. Interestingly, a broad range of viruses have been identified to activate and/or require GPCR-mediated pathways for infection, including polyomaviruses, flaviviruses, influenza virus, and SARS-CoV-2, demonstrating that these viruses may have conserved mechanisms of host-cell invasion. Thus, GPCR-mediated pathways highlight an attractive target for the development of broad antiviral therapies.

The Roles of GRKs in Hemostasis and Thrombosis.

Along with cancer, cardiovascular and cerebrovascular diseases remain by far the most common causes of death. Heart attacks and strokes are diseases in which platelets play a role, through activation on ruptured plaques and subsequent thrombus formation. Most platelet agonists activate platelets via G protein-coupled receptors (GPCRs), which make these receptors ideal targets for many antiplatelet drugs. However, little is known about the mechanisms that provide feedback regulation on GPCRs to limit platelet activation. Emerging evidence from our group and others strongly suggests that GPCR kinases (GRKs) are critical negative regulators during platelet activation and thrombus formation. In this review, we will summarize recent findings on the role of GRKs in platelet biology and how one specific GRK, GRK6, regulates the hemostatic response to vascular injury. Furthermore, we will discuss the potential role of GRKs in thrombotic disorders, such as thrombotic events in COVID-19 patients. Studies on the function of GRKs during platelet activation and thrombus formation have just recently begun, and a better understanding of the role of GRKs in hemostasis and thrombosis will provide a fruitful avenue for understanding the hemostatic response to injury. It may also lead to new therapeutic options for the treatment of thrombotic and cardiovascular disorders.