Purinoceptor regulation of renal tubular transport is coming of age

Purinergic signalling in the kidney in health and disease

The involvement of purinergic signalling in kidney physiology and pathophysiology is rapidly gaining recognition and this is a comprehensive review of early and recent publications in the field. Purinergic signalling involvement is described in several important intrarenal regulatory mechanisms, including tuboglomerular feedback, the autoregulatory response of the glomerular and extraglomerular microcirculation and the control of renin release. Furthermore, purinergic signalling influences water and electrolyte transport in all segments of the renal tubule. Reports about purine- and pyrimidine-mediated actions in diseases of the kidney, including polycystic kidney disease, nephritis, diabetes, hypertension and nephrotoxicant injury are covered and possible purinergic therapeutic strategies discussed.

The P2Y13 receptor regulates phosphate metabolism and FGF-23 secretion with effects on skeletal development

Purinergic signaling mediates many cellular processes, including embryonic development and regulation of endocrine signaling. The ADP P2Y13 receptor is known to regulate bone and stem cells activities, although relatively little is known about its role in bone development. In this study we demonstrate, using contemporary techniques, that deletion of the P2Y13 receptor results in an age-dependent skeletal phenotype that is governed by changes in phosphate metabolism and hormone levels. Neonatal and postnatal (2 wk) P2Y13 receptor-knockout (KO) mice were indistinguishable from their wild-type (WT) littermate controls. A clear bone phenotype was observed in young (4-wk-old) KO mice compared WT controls, with 14% more trabecular bone, 35% more osteoblasts, 73% fewer osteoclasts, and a 17% thicker growth plate. Mature (>10 wk of age) KO mice showed the opposite bone phenotype, with 14% less trabecular bone, 22% fewer osteoblasts, and 10% thinner growth plate. This age-dependent phenotype correlated with serum fibroblast growth factor-23 (FGF-23) and phosphorus levels that were 65 and 16% higher, respectively, in young KO mice but remained unchanged in mature mice. These findings provide novel insights for the role of the P2Y13 receptor in skeletal development via coordination with hormonal regulators of phosphate homeostasis.