Phosphate-Mediated Regulation of Intracellular Calcium Dynamics.

Phosphate (Pi) and calcium (Ca2+) are essential mineral ions that play coordinated roles in maintaining normal cellular functions. While various steps of calcium signaling are well characterized, emerging evidence suggests the critical role of both intracellular and extra cellular phosphate in regulating intracellular Ca2+. In the cytoplasm, phosphate influences ATP production and organelle calcium buffering and influences the activity of calcium pumps, such as sarcoplasmic/endoplasmic reticulum Ca2+-ATPase (SERCA) and the plasma membrane Ca2+-ATPase (PMCA). Extracellular phosphate, taken up via sodium-dependent phosphate transporters, triggers signaling cascades that affect the processes of calcium influx, storage, and release. Additionally, high extracellular phosphate levels can disrupt calcium homeostasis through the systemic interactions of hormones such as fibroblast growth factor 23 (FGF23), vitamin D and parathyroid hormone (PTH), especially under pathological conditions such as chronic kidney disease (CKD). This article briefly summarizes the current understanding of the bidirectional influence of intra- and extracellular phosphate on calcium dynamics at the cellular level, with a focus on the underlying mechanisms.