Huynh Nha V, Mendoza Luciano D, Nguyen Hung, Rehage Cassidy, Saurage Elizabeth B, Davis Parker, Hyndman Kelly A
Section of Cardio-Renal Physiology and Medicine, Division of Nephrology, Department of Medicine, University of Alabama at Birmingham, Birmingham, Alabama, United States.
Am J Physiol Renal Physiol. 2025 Apr 1;328(4):F517-F529. doi: 10.1152/ajprenal.00037.2025. Epub 2025 Mar 10.
Aquaporin-3 (AQP3) mediates basolateral water transport in the kidney principal cells contributing to urine concentration. We previously identified the acetylation of lysine 282 (K282) in the C-terminus of AQP3, which we hypothesized as a positive regulator of AQP3 water permeability. AQP3 acetylation (K282Q or Q) or deacetylation (K282R or R) mimetic mutant mice models were created using CRISPR/Cas9. Male and female wild-type (WT) and mutant mice were assigned to hydrating diets and water deprivation protocols. Urine and plasma osmolality in response to acute vasopressin receptor-2 activation with desmopressin (dDAVP) or inhibition by tolvaptan were determined. In vitro water permeability of murine principal kidney cortical collecting duct (mpkCCD) cells stably expressing AQP3 WT, Q, or R was measured. Acetylated AQP3 was prominent in the cortical to inner medullary collecting ducts of dehydrated versus hydrated mice. At baseline, the mutations did not affect the kidney transcriptome, AQP3 abundance, or subcellular localization. Urine osmolality of the mutant mice was within the normal range. With dehydration, all mice excreted concentrated urine; however, the female Q mutants exhibited significantly greater 24-h urine osmolality than WT, suggesting greater water reabsorption. In response to acute dDAVP, all mice produced concentrated urine; however, female Q mutants had a more dilute plasma than WT, further suggesting greater water retention. mpkCCD Q mutant cells exhibited greater water permeability than WT and R cells. We conclude that AQP3 K282 acetylation promotes principal cell water permeability in a sex-dependent manner; however, it is not essential for urine concentration. The water channel, AQP3, is lysine 282 acetylated (acAQP3) in rodents and humans. When dehydrated, mouse cortical to inner medullary collecting ducts express acAQP3, suggesting that it promotes water reabsorption. acAQP3 expressing principal cells have high water permeability, and in vivo acute desmopressin resulted in a dilute plasma in female acAQP3 mice. However, all mice produced concentrated urine during water deprivation. Thus, acAQP3 promotes water permeability but is not essential for urine concentration during antidiuresis.
水通道蛋白3（AQP3）介导肾脏主细胞基底外侧的水转运，有助于尿液浓缩。我们之前鉴定了AQP3 C末端赖氨酸282（K282）的乙酰化，我们推测其为AQP3水通透性的正向调节因子。使用CRISPR/Cas9创建了AQP3乙酰化（K282Q或Q）或去乙酰化（K282R或R）模拟突变小鼠模型。将雄性和雌性野生型（WT）及突变小鼠分配到补水饮食和禁水方案中。测定了用去氨加压素（dDAVP）急性激活血管加压素受体2或用托伐普坦抑制后尿液和血浆的渗透压。测量了稳定表达AQP3 WT、Q或R的小鼠主肾皮质集合管（mpkCCD）细胞的体外水通透性。与补水小鼠相比，脱水小鼠皮质至髓质内集合管中乙酰化的AQP3更为显著。在基线时，这些突变不影响肾脏转录组、AQP3丰度或亚细胞定位。突变小鼠的尿渗透压在正常范围内。脱水时，所有小鼠均排出浓缩尿；然而，雌性Q突变体的24小时尿渗透压显著高于WT，表明水重吸收更多。对急性dDAVP的反应中，所有小鼠均产生浓缩尿；然而，雌性Q突变体的血浆比WT更稀释，进一步表明水潴留更多。mpkCCD Q突变体细胞的水通透性高于WT和R细胞。我们得出结论，AQP3 K282乙酰化以性别依赖的方式促进主细胞水通透性；然而，它对尿液浓缩并非必不可少。水通道蛋白AQP3在啮齿动物和人类中赖氨酸282被乙酰化（acAQP3）。脱水时，小鼠皮质至髓质内集合管表达acAQP3，表明其促进水重吸收。表达acAQP3的主细胞具有高水通透性，体内急性去氨加压素导致雌性acAQP3小鼠血浆稀释。然而，所有小鼠在禁水期间均产生浓缩尿。因此，acAQP3促进水通透性，但在抗利尿期间对尿液浓缩并非必不可少。
