HGF induces the serine‑phosphorylation and cell surface translocation of ROMK (Kir 1.1) channels in rat kidney cells.

Extracellular potassium homeostasis is dependent on the activity of potassium channels, which are expressed on the apical membrane of epithelial tubular cells. The renal outer medullary potassium channel (ROMK) is considered to be the major route for potassium transport into the tubule lumen. Hepatocyte growth factor (HGF) exerts multiple biological activities and is important for maintaining renal homeostasis. It is also anti-apoptotic and mitogenic for protection and recovery from ARF. Whether HGF regulates the ion channel activities remains to be elucidated, therefore, the present study aimed to investigate the modulation of HGF on the expression of ROMK in cultured renal tubular cells. NRK-52E cells were treated with recombinant HGF, however, no alterations in the total expression of ROMK were observed by western blot analysis. In examining the serine 44 phosphorylation of ROMK in NRK-52E cells, the present study observed that HGF enhanced the serine 44 phosphorylation of ROMK. In addition, to investigate whether HGF-Met signaling induces the movement of ROMK to the cell surface in NRK-52E cells, the protein constituents of cells were separated into plasma membrane and cytoplasm. Using immunofluorescence assay, the expression of ROMK on the plasma membrane was increased in the HGF-treated NRK-52E cells, which suggested that ROMK was translocated to the plasma membrane following the HGF-induced phosphorylation of serine 44. Therefore, HGF may be important in potassium excretion and perform antihyperkalemic effects through the translocation of potassium channels.