Prokineticin receptor 1 (PKR1) signalling in cardiovascular and kidney functions.

Prokineticins (PK1 and PK2) are peptide hormones that exert their biological activity via two common G-protein-coupled receptors: prokineticin receptor (PKR) 1 and 2. Their physiology was originally explored mostly in the context of angiogenic actions in the reproductive tract and gut motility. Since autocrine and paracrine loops have been established between PK2 and PKR1 in the heart, in this review we focus on the PK2/PKR1 signalling in the functions of the heart and kidney. PKR1 signalling is required for cardiomyocyte survival and angiogenesis. In the mouse model of myocardial infarction, intracardiac transient PKR1 transfection protects the structure and function of the heart. Gain- and loss-of-function studies reveal that PKR1 in mouse heart up-regulates its own ligand and PK2, which in turn acts as a paracrine signal and promotes epicardin-positive progenitor cell differentiation into a vasculogenic cell type. Transgenic mice over-expressing PKR1 in cardiomyocytes exhibit increased neovascularization. Loss of PKR1 causes structural and functional changes in the heart and kidney. In isolated epicardin-positive progenitor cells from the kidney, PK2, acting via PKR1, stimulates differentiation of these progenitor cells into endothelial and smooth muscle cells. Taken together, these data show that PK2/PKR1 is involved in postnatal cardiac and renal neovascularization. The knowledge gained from these studies should facilitate the discovery of therapeutic interventions in heart and kidney diseases targeting PKR1.