Endocrine Abstracts

Despite significant progress in understanding the regulation of phosphate (Pi) homeostasis over the past 20 years, the mechanisms underlying the very early step leading to the regulating cascade involving multiple hormones (PTH, vitamin D, FGF23) and organs (kidney, intestine, bone, parathyroid glands) are not deciphered. Progress in this area is based on on the ability to identify and characterise the Pi-sensing mechanism in mammals that allow cells or organisms to detect changes in extracellular Pi levels and trigger appropriate responses. While the molecular players involved in Pi-sensing mechanisms in prokaryotes, yeasts, and plants are well characterised, the molecular actors involved in the detection of Pi in mammals and the mechanisms underlying the Pi-dependent synthesis and/or secretion of FGF23 are poorly defined. We are just beginning to accumulate in vitro and in vivo data that provide invaluable molecular tools to explore and understand the integrated response of the body to variations in extracellular Pi concentration. Particularly, several molecular actors have recently been involved as potential key players in Pi sensing and Pi-dependent control of FGF23 secretion. Among them, the involvement of PiT1/Slc20a1 and PiT2/Slc20a2 proteins is these mechanisms is standing out. We propose here an updated overview describing the main recent key molecular actors in Pi-sensing and Pi-dependent FGF23 secretion.