• The Korean Journal of Physiology and Pharmacology
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• v.19 no.3
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• pp.249-255
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• 2015

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 $Ca^{2+}$ 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 $Ca^{2+}$ concentration ($[Ca^{2+}]_i$) increase in response to hypotonic stimulation, and the response was synchronized with the phosphorylation of OSR1. Interestingly, when we inhibited the hypotonically induced $[Ca^{2+}]_i$ increase with nonspecific $Ca^{2+}$ channel blockers such as 2-aminoethoxydiphenyl borate, gadolinium, and lanthanum, the phosphorylated OSR1 level was also diminished. Moreover, a cyclopiazonic acid-induced passive $[Ca^{2+}]_i$ elevation was evoked by the phosphorylation of OSR1, and the amount of phosphorylated OSR1 decreased when the cells were treated with BAPTA, a $Ca^{2+}$ chelator. Finally, through that process, NKCC1 activity also decreased to maintain the cell volume in the HSG cell line. These results indicate that $Ca^{2+}$ may regulate the WNK-OSR1 pathway and NKCC1 activity in the HSG cell line. This is the first demonstration that indicates upstream $Ca^{2+}$ regulation of the WNK-OSR1 pathway in intact cells.

• The Korean Journal of Physiology and Pharmacology
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• v.25 no.5
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• pp.449-457
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• 2021

The sleep-wake cycle is regulated by the alternating activity of sleep- and wake-promoting neurons. The dorsal raphe nucleus (DRN) secretes 5-hydroxytryptamine (5-HT, serotonin), promoting wakefulness. Melatonin secreted from the pineal gland also promotes wakefulness in rats. Our laboratory recently demonstrated that daily changes in nitric oxide (NO) production regulates a signaling pathway involving with-no-lysine kinase (WNK), Ste20-related proline alanine rich kinase (SPAK)/oxidative stress response kinase 1 (OSR1), and cation-chloride co-transporters (CCC) in rat DRN serotonergic neurons. This study was designed to investigate the effect of melatonin on NO-regulated WNK-SPAK/OSR1-CCC signaling in wake-inducing DRN neurons to elucidate the mechanism underlying melatonin's wake-promoting actions in rats. Ex vivo treatment of DRN slices with melatonin suppressed neuronal nitric oxide synthase (nNOS) expression and increased WNK4 expression without altering WNK1, 2, or 3. Melatonin increased phosphorylation of OSR1 and the expression of sodium-potassium-chloride co-transporter 1 (NKCC1), while potassium-chloride co-transporter 2 (KCC2) remained unchanged. Melatonin increased the expression of tryptophan hydroxylase 2 (TPH2, serotonin-synthesizing enzyme). The present study suggests that melatonin may promote its wakefulness by modulating NO-regulated WNK-SPAK/OSR1-KNCC1 signaling in rat DRN serotonergic neurons.

• Journal of the Ergonomics Society of Korea
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• v.28 no.3
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• pp.87-94
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• 2009

The aim of the study is to investigate the usability of wheel navigation key(WNK) recently adopted for the new models of mobile phone and MP3 product. In this study, an experiment was designed to evaluate the functional benefit of WNK by using a performance test. A questionnaire was also used to examine the personal preference. In results, a significant difference was found in performance time between wheel-type and button-type product. In general, the difference was more significant as subject's skill level was higher. In particular, the performance time was significantly shortened with the WNK when a searching task was required, but push button was an effective interface for simple search task among beginners. Therefore, the wheel navigation key can be used to improve the usability of product by reducing the searching time in mobile phone and mp3. For practical application, the user's level of skill needs to be considered to maximize the effect of interface when choosing WNK or push button.

• The Korean Journal of Physiology and Pharmacology
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• v.22 no.1
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• pp.91-99
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• 2018

Protein phosphatase 1 (PP1) is involved in various signal transduction mechanisms as an extensive regulator. The PP1 catalytic subunit (PP1c) recognizes and binds to PP1-binding consensus residues (FxxR/KxR/K) in NBCe1-B. Consequently, we focused on identifying the function of the PP1-binding consensus residue, $^{922}FMDRLK^{927}$, in NBCe1-B. Using site-directed mutagenesis and co-immunoprecipitation assays, we revealed that in cases where the residues were substituted (F922A, R925A, and K927A) or deleted (deletion of amino acids 922-927), NBCe1-B mutants inhibited PP1 binding to NBCe1-B. Additionally, by recording the intracellular pH, we found that PP1-binding consensus residues in NBCe1-B were not only critical for NBCe1-B activity, but also relevant to its surface expression level. Therefore, we reported that NBCe1-B, as a substrate of PP1, contains these residues in the C-terminal region and that the direct interaction between NBCe1-B and PP1 is functionally critical in controlling the regulation of the ${HCO_3}^-$ transport. These results suggested that like IRBIT, PP1 was another novel regulator of ${HCO_3}^-$ secretion in several types of epithelia.