WNK1 promotes water homeostasis by acting as a central osmolality sensor for arginine vasopressin release
Xin Jin, … , Cheng-Chang Lien, Chou-Long Huang
Xin Jin, … , Cheng-Chang Lien, Chou-Long Huang
Published April 18, 2023
Citation Information: J Clin Invest. 2023;133(11):e164222. https://doi.org/10.1172/JCI164222.
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Research Article Endocrinology Nephrology

WNK1 promotes water homeostasis by acting as a central osmolality sensor for arginine vasopressin release

Abstract

Maintaining internal osmolality constancy is essential for life. Release of arginine vasopressin (AVP) in response to hyperosmolality is critical. Current hypotheses for osmolality sensors in circumventricular organs (CVOs) of the brain focus on mechanosensitive membrane proteins. The present study demonstrated that intracellular protein kinase WNK1 was involved. Focusing on vascular-organ-of-lamina-terminalis (OVLT) nuclei, we showed that WNK1 kinase was activated by water restriction. Neuron-specific conditional KO (cKO) of Wnk1 caused polyuria with decreased urine osmolality that persisted in water restriction and blunted water restriction–induced AVP release. Wnk1 cKO also blunted mannitol-induced AVP release but had no effect on osmotic thirst response. The role of WNK1 in the osmosensory neurons in CVOs was supported by neuronal pathway tracing. Hyperosmolality-induced increases in action potential firing in OVLT neurons was blunted by Wnk1 deletion or pharmacological WNK inhibitors. Knockdown of Kv3.1 channel in OVLT by shRNA reproduced the phenotypes. Thus, WNK1 in osmosensory neurons in CVOs detects extracellular hypertonicity and mediates the increase in AVP release by activating Kv3.1 and increasing action potential firing from osmosensory neurons.

Authors

Xin Jin, Jian Xie, Chia-Wei Yeh, Jen-Chi Chen, Chih-Jen Cheng, Cheng-Chang Lien, Chou-Long Huang

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Figure 8

Knockdown of Kv3.1 by shRNA in OVLT causes partial central diabetes insipidus and impairs copeptin release in response to water restriction.

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Knockdown of Kv3.1 by shRNA in OVLT causes partial central diabetes insi...
(A) OVLT tissues from mice with direct injection scrambled RNA (Ctrl) or shRNA against Kv3.1 were probed by antibody against Kv3.1b. Note that the Kv3.1 shRNA targets both alternatively spliced Kv3.1a and Kv3.1b isoforms. (B) Mean ± SEM of Kv3.1b protein abundance from 3 separate experiments as shown in A (data from each experiment is the average of triplicate samples). Statistical analysis by unpaired t test. (C) Urine volume, (D) urine osmolality, (E) plasma osmolality, and (F) copeptin levels of mice injected with control scrambled RNA (labeled –) or shRNA against Kv3.1b (labeled +) into OVLT and at either ad libitum water intake or after 24-hour water restriction (WR). Unpaired t test for comparison between control scrambled RNA and Kv3.1 shRNA in B. In C–F, n = 5 mice per group injected with control scrambled or with Kv3.1b shRNA as indicated in scatter plots. Statistical analysis was performed with by 2-way repeated ANOVA with Šidák post hoc analysis.