Korean J Physiol Pharmacol.  2015 May;19(3):249-255. 10.4196/kjpp.2015.19.3.249.

Ca2+ is a Regulator of the WNK/OSR1/NKCC Pathway in a Human Salivary Gland Cell Line

• Park S
• Ku SK
• Ji HW
• Choi JH
• Shin DM

• KMID: 1791426
• DOI: http://doi.org/10.4196/kjpp.2015.19.3.249

Abstract

Wnk kinase maintains cell volume, regulating various transporters such as sodium-chloride cotransporter, potassium-chloride cotransporter, and sodium-potassium-chloride cotransporter 1 (NKCC1) through the phosphorylation of oxidative stress responsive kinase 1 (OSR1) and STE20/SPS1-related proline/alanine-rich kinase (SPAK). However, the activating mechanism of Wnk kinase in specific tissues and specific conditions is broadly unclear. In the present study, we used a human salivary gland (HSG) cell line as a model and showed that Ca2+ may have a role in regulating Wnk kinase in the HSG cell line. Through this study, we found that the HSG cell line expressed molecules participating in the WNK-OSR1-NKCC pathway, such as Wnk1, Wnk4, OSR1, SPAK, and NKCC1. The HSG cell line showed an intracellular Ca2+ concentration ([Ca2+]i) increase in response to hypotonic stimulation, and the response was synchronized with the phosphorylation of OSR1. Interestingly, when we inhibited the hypotonically induced [Ca2+]i increase with nonspecific Ca2+ channel blockers such as 2-aminoethoxydiphenyl borate, gadolinium, and lanthanum, the phosphorylated OSR1 level was also diminished. Moreover, a cyclopiazonic acid-induced passive [Ca2+]i elevation was evoked by the phosphorylation of OSR1, and the amount of phosphorylated OSR1 decreased when the cells were treated with BAPTA, a Ca2+ chelator. Finally, through that process, NKCC1 activity also decreased to maintain the cell volume in the HSG cell line. These results indicate that Ca2+ may regulate the WNK-OSR1 pathway and NKCC1 activity in the HSG cell line. This is the first demonstration that indicates upstream Ca2+ regulation of the WNK-OSR1 pathway in intact cells.

Keyword

Ca2+ signaling; NKCC; OSR1; Salivary gland; WNK

MeSH Terms

Cell Line*
Cell Size
Gadolinium
Humans
Lanthanum
Oxidative Stress
Phosphorylation
Phosphotransferases
Salivary Glands*
Sodium Chloride Symporters
Sodium-Potassium-Chloride Symporters
Gadolinium
Lanthanum
Phosphotransferases
Sodium Chloride Symporters
Sodium-Potassium-Chloride Symporters