The Prorenin Receptor: Multitasking Its Way Through Cardiovascular, Metabolic and Renal Diseases

The renin–angiotensin–aldosterone system (RAAS) is a fundamental regulator of blood pressure, electrolyte balance, fluid homeostasis, and tissue remodeling. The discovery of the prorenin receptor (PRR), the protein encoded by the ATP6AP2 gene, has substantially expanded the classical RAAS paradigm by demonstrating that prorenin possesses biological activity beyond its proteolytic conversion to renin. Binding of renin or prorenin to PRR enhances local angiotensin II (Ang II) generation while simultaneously initiating Ang II-independent intracellular signaling pathways, including ERK1/2, mitogen-activated protein kinases, PI3K/Akt, transforming growth factor-β, and nuclear factor-κB, thereby promoting inflammation, oxidative stress, fibrosis, cellular proliferation, and extracellular matrix accumulation. Beyond its receptor function, PRR serves as an essential accessory component of the vacuolar H+-ATPase (V-ATPase) complex, regulating vesicular acidification, lysosomal function, autophagy, protein trafficking, cellular metabolism, and Wnt/β-catenin signaling. These diverse functions explain its indispensable role in embryonic development, cell differentiation, and tissue homeostasis, as evidenced by the embryonic lethality associated with ATP6AP2 gene deficiency. PRR is predominantly localized to intracellular organelles, including the endoplasmic reticulum, Golgi apparatus, endosomes, lysosomes, and autophagic vesicles, although membrane-bound and soluble forms also contribute to physiological and pathological processes. Increasing evidence implies dysregulated PRR signaling in the development and progression of hypertension, cardiovascular disease, chronic kidney disease, diabetes, obesity, and other metabolic disorders. This review summarizes current advances in PRR and soluble PRR biology, discusses unresolved mechanistic and translational questions, and evaluates the potential of PRR as a biomarker and therapeutic target for cardiovascular, renal, and metabolic diseases.