Generation and phenotype of mice harboring a nonsense mutation in the V2 vasopressin receptor gene

Yun, June; Schöneberg, Torsten; Liu, Jie; Schulz, Angela; Ecelbarger, Carolyn A.; Promeneur, Dominique; Nielsén, Sören; Sheng, Hua; Grinberg, Alexander; Deng, Chu Xia; Wess, Jürgen

doi:10.1172/jci9154

Cited by 107 publications

(66 citation statements)

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“…For several reasons, we believe that the early death is because of polyuria and its consequences, rather than to other causes related to expression of the mutated AQP2 protein. First, mice lacking an unrelated protein (the V2 receptor), which probably have comparable polyuria to the mutant AQP2 mice, also fail to thrive and die early (32). Other knockout mouse models (AQP3, NKCC2) having polyuria appear to develop kidney damage (33,34).…”

Section: Discussionmentioning

confidence: 99%

Neonatal Mortality in an Aquaporin-2 Knock-in Mouse Model of Recessive Nephrogenic Diabetes Insipidus

Yang

Gillespie

Carlson

et al. 2001

Journal of Biological Chemistry

155

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Hereditary non-X-linked nephrogenic diabetes insipidus (NDI) is caused by mutations in the aquaporin-2 (AQP2) water channel. In transfected cells, the human disease-causing mutant AQP2-T126M is retained at the endoplasmic reticulum (ER) where it is functional and targetable to the plasma membrane with chemical chaperones. A mouse knock-in model of NDI was generated by targeted gene replacement using a Cre-loxP strategy. Along with T126M, mutations H122S, N124S, and A125T were introduced to preserve the consensus sequence for N-linked glycosylation found in human AQP2. Breeding of heterozygous mice yielded the expected Mendelian distribution with 26 homozygous mutant offspring of 99 live births. The mutant mice appeared normal at 2-3 days after birth but failed to thrive and generally died by day 6 if not given supplemental fluid. Urine/serum analysis showed a urinary concentrating defect with serum hyperosmolality and low urine osmolality that was not increased by a V2 vasopressin agonist. Northern blot analysis showed up-regulated AQP2-T126M transcripts of identical size to wild-type AQP2. Immunoblots showed complex glycosylation of wild-type AQP2 but mainly endoglycosidase H-sensitive core glycosylation of AQP2-T126M indicating ER-retention. Biochemical analysis revealed that the AQP2-T126M protein was resistant to detergent solubilization. Kidneys from mutant mice showed collecting duct dilatation, papillary atrophy, and unexpectedly, some plasma membrane AQP2 staining. The severe phenotype of the AQP2 mutant mice compared with that of mice lacking kidney water channels AQP1, AQP3, and AQP4 indicates a critical role for AQP2 in neonatal renal function in mice. Our results establish a mouse model of human autosomal NDI and provide the first in vivo biochemical data on a diseasecausing AQP2 mutant.The formation of concentrated urine by the kidney requires high osmotic water permeability across the collecting duct epithelium. Collecting duct epithelial cells express aquaporin water channels AQP2, 1 AQP3, and AQP4 (1-4). AQP2 is the vasopressin (antidiuretic hormone)-regulated water channel (5, 6). Vasopressin induces the fusion of intracellular vesicles containing AQP2 with the apical plasma membrane resulting in increased water permeability (7-9). AQP2 is of considerable clinical importance in fluid and electrolyte balance. Mutations in human AQP2 cause hereditary non-X-linked nephrogenic diabetes insipidus (10 -13). Down-regulation of AQP2 expression occurs in several forms of acquired NDI (14), and AQP2 up-regulation is important in the pathophysiology of fluidretaining states such as congestive heart failure (15, 16). AQP3 and AQP4 are expressed constitutively at the basolateral membrane of collecting duct epithelial cells, with AQP3 mainly in cortical collecting duct and AQP4 in inner medullary collecting duct. Transgenic mice lacking AQP3 have low water permeability in cortical collecting duct and manifest NDI with marked polyuria and decreased urine osmolality (17). In contrast, mice lacking AQP4 show onl...

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Section: Discussionmentioning

confidence: 99%

Neonatal Mortality in an Aquaporin-2 Knock-in Mouse Model of Recessive Nephrogenic Diabetes Insipidus

Yang

Gillespie

Carlson

et al. 2001

Journal of Biological Chemistry

155

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“…Considering the low stability of ER-retained folding mutants (8), the lack of increased V2R mutant degradation upon activation by nonpeptide agonists provides an additional advantage for their therapeutic use. Determination of their in vivo therapeutic value for NDI, however, awaits approval for their use and testing in patients, because mice lacking functional V2Rs die soon after birth (30) and OPC51 (803), VA (9990)88, and VA(9990)89-like compounds are still in early phase clinical trials. However, the observed decrease in urine output with OPC51803 in Brattleboro rats, which have functional V2Rs but lack AVP, already reveals the in vivo activity of nonpeptide V2R agonists on a normal functioning renal concentrating mechanism (29) and underscores the potential of nonpeptide V2R agonists as therapeutic agents for NDI patients due to retained, but intrinsicallyfunctional, V2R mutants.…”

Section: Potential Implications Of the Use Of V2r Nonpeptide Agonistsmentioning

confidence: 99%

Intracellular activation of vasopressin V2 receptor mutants in nephrogenic diabetes insipidus by nonpeptide agonists

Robben

Kortenoeven²,

Sze³

et al. 2009

Proc. Natl. Acad. Sci. U.S.A.

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Binding of the peptide hormone vasopressin to its type-2 receptor (V2R) in kidney triggers a cAMP-mediated translocation of Aquaporin-2 water channels to the apical membrane, resulting in water reabsorption and thereby preventing dehydration. Mutations in the V2R gene lead to Nephrogenic Diabetes Insipidus (NDI), a disorder in which this process is disturbed, because the encoded, often intrinsically functional mutant V2 receptors are misfolded and retained in the endoplasmic reticulum (ER). Since plasma membrane expression is thought to be essential for V2R activation, cell permeable V2R antagonists have been used to induce maturation and rescue cell surface expression of V2R mutants, after which they need to be displaced by vasopressin for activation. Here, however, we show that 3 novel nonpeptide V2R agonists, but not vasopressin, activate NDI-causing V2R mutants at their intracellular location, without changing their maturation and at a sufficient level to induce the translocation of aquaporin-2 to the apical membrane. Moreover, in contrast to plasma membrane V2R, degradation of intracellular V2R mutants is not increased by their activation. Our data reveal that G protein-coupled receptors (GPCRs) normally active at the plasma membrane can be activated intracellularly and that intracellular activation does not induce their degradation; the data also indicate that nonpeptide agonists constitute highly promising therapeutics for diseases caused by misfolded GPCRs in general, and NDI in particular.GPCR ͉ pharmacological chaperones ͉ signaling ͉ ER retention ͉ osmoregulation

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“…Symptoms include excessive thirst, excretion of a large volume of dilute urine, and electrolyte imbalances, including hypernatremia (1,5). Hereditary forms of this disease appear in patients with inactivating mutations in the V2 vasopressin receptor (V2R) or AQP2 (9)(10)(11)(12). Thus, understanding the molecular mechanisms that govern bidirectional control of AQP2 location may lead to new therapeutic approaches for the treatment of NDI.…”

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confidence: 99%

AKAP220 manages apical actin networks that coordinate aquaporin-2 location and renal water reabsorption

Whiting

Ogier

Forbush

et al. 2016

Proc. Natl. Acad. Sci. U.S.A.

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Filtration through the kidney eliminates toxins, manages electrolyte balance, and controls water homeostasis. Reabsorption of water from the luminal fluid of the nephron occurs through aquaporin-2 (AQP2) water pores in principal cells that line the kidney-collecting duct. This vital process is impeded by formation of an "actin barrier" that obstructs the passive transit of AQP2 to the plasma membrane. Bidirectional control of AQP2 trafficking is managed by hormones and signaling enzymes. We have discovered that vasopressin-independent facets of this homeostatic mechanism are under the control of A-Kinase Anchoring Protein 220 (AKAP220; product of the Akap11 gene). CRISPR/Cas9 gene editing and imaging approaches show that loss of AKAP220 disrupts apical actin networks in organoid cultures. Similar defects are evident in tissue sections from AKAP220-KO mice. Biochemical analysis of AKAP220-null kidney extracts detected reduced levels of active RhoA GTPase, a well-known modulator of the actin cytoskeleton. Fluorescent imaging of kidney sections from these genetically modified mice revealed that RhoA and AQP2 accumulate at the apical surface of the collecting duct. Consequently, these animals are unable to appropriately dilute urine in response to overhydration. We propose that membrane-proximal signaling complexes constrained by AKAP220 impact the actin barrier dynamics and AQP2 trafficking to ensure water homeostasis. yet only approximately 1.5 L of urine is excreted. The majority of this water is reabsorbed from the luminal fluid of the nephron (1). Regulated water reabsorption in response to dehydration occurs through aquaporin-2 (AQP2) water pores in the principal cells of the collecting duct (2). This is stimulated by the hormone arginine vasopressin (AVP). Vasopressin induces PKA phosphorylation of serine 256 on AQP2 and stimulates its translocation from intracellular vesicles to the apical membranes of cells lining the collecting ducts. Reabsorption of water through the kidney preserves fluid balance and results in more concentrated urine (3, 4). Conversely, when an animal ingests excess water, decreased plasma osmolality inhibits vasopressin release, and AQP2 is recovered from the apical membrane by endocytosis. This renders the collecting duct impermeable to water, thereby diverting excess water through the ureter to the bladder.Not surprisingly, defects in AQP2 trafficking have pathophysiological outcomes. For example, nephrogenic diabetes insipidus (NDI) is associated with impaired vasopressin signaling to AQP2 (5-8). Symptoms include excessive thirst, excretion of a large volume of dilute urine, and electrolyte imbalances, including hypernatremia (1, 5). Hereditary forms of this disease appear in patients with inactivating mutations in the V2 vasopressin receptor (V2R) or AQP2 (9-12). Thus, understanding the molecular mechanisms that govern bidirectional control of AQP2 location may lead to new therapeutic approaches for the treatment of NDI.Although the enzymes and effector proteins that govern AQP2 in...

show abstract

Generation and phenotype of mice harboring a nonsense mutation in the V2 vasopressin receptor gene

Cited by 107 publications

References 50 publications

Neonatal Mortality in an Aquaporin-2 Knock-in Mouse Model of Recessive Nephrogenic Diabetes Insipidus

Neonatal Mortality in an Aquaporin-2 Knock-in Mouse Model of Recessive Nephrogenic Diabetes Insipidus

Intracellular activation of vasopressin V2 receptor mutants in nephrogenic diabetes insipidus by nonpeptide agonists

AKAP220 manages apical actin networks that coordinate aquaporin-2 location and renal water reabsorption

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