Aquaporin 2

Aquaporin 2

Aquaporin 2 (collecting duct)
Available structures
PDB Ortholog search: PDBe, RCSB
Symbols  ; AQP-CD; WCH-CD
External IDs IUPHAR: GeneCards:
RNA expression pattern
Species Human Mouse
RefSeq (mRNA)
RefSeq (protein)
Location (UCSC)
PubMed search

AQP2 is found in the apical cell membranes of the kidney's collecting duct principal cells and in intracellular vesicles located throughout the cell.


  • Regulation 1
  • Clinical significance 2
  • See also 3
  • References 4
  • Further reading 5
  • External links 6


It is the only aquaporin regulated by vasopressin.[1] The basic job of aquaporin 2 is to reabsorb water from the urine while its being removed from the blood by the kidney. Aquaporin 2 is in kidney epithelial cells and usually lies dormant in intracellular vesicle membranes, but when it is needed vasopressin binds to the cell surface vasopressin receptor, activating a signaling pathway that causes the aquaporin 2 containing vesicles to fuse with the plasma membrane so the aquaporin 2 can be used by the cell.[2]

This aquaporin is regulated in two ways by the peptide hormone vasopressin:

  • short-term regulation (minutes) through trafficking of AQP2 vesicles to the apical region where they fuse with the apical plasma membrane
  • long-term regulation (days) through an increase in AQP2 gene expression.

This aquaporin is also regulated by food intake. Fasting reduces expression of this aquaporin independently of vasopressin.

Clinical significance

Mutations in this channel are associated with nephrogenic diabetes insipidus, which can be autosomal dominant or recessive. Mutations in the vasopressin receptor cause a similar X-linked phenotype.

Lithium, which is often used to treat bipolar disorder, can cause acquired diabetes insipidus (characterized by the excretion of large volumes of dilute urine) by decreasing the expression of the AQP2 gene.

The expression of the AQP2 gene is increased during conditions associated with water retention such as pregnancy and congestive heart failure.

See also


  1. ^ Dibas AI, Mia AJ, Yorio T (1998). "Aquaporins (water channels): role in vasopressin-activated water transport". Proc. Soc. Exp. Biol. Med. 219 (3): 183–99.  
  2. ^ Lodish, Harvey F. Molecular Cell Biology. New York: W.H. Freeman, 2008. Print. 445.

Further reading

  • Bichet DG (2006). "Nephrogenic diabetes insipidus". Advances in chronic kidney disease 13 (2): 96–104.  
  • Bouley R, Hasler U, Lu HAJ, Nunes P, Brown D (2008). "Bypassing vasopressin signaling pathways in nephrogenic diabetes insipidus". Sem. Nephrol. 28 (3): 266–78.  
  • Robben JH, Knoers NV, Deen PM (2006). "Cell biological aspects of the vasopressin type-2 receptor and aquaporin 2 water channel in nephrogenic diabetes insipidus". Am. J. Physiol. Renal Physiol. 291 (2): F257–70.  
  • Sasaki S, Fushimi K, Saito H, et al. (1994). "Cloning, characterization, and chromosomal mapping of human aquaporin of collecting duct". J. Clin. Invest. 93 (3): 1250–6.  
  • Deen PM, Weghuis DO, Sinke RJ, et al. (1994). "Assignment of the human gene for the water channel of renal collecting duct Aquaporin 2 (AQP2) to chromosome 12 region q12→q13". Cytogenet. Cell Genet. 66 (4): 260–2.  
  • Uchida S, Sasaki S, Fushimi K, Marumo F (1994). "Isolation of human aquaporin-CD gene". J. Biol. Chem. 269 (38): 23451–5.  
  • van Lieburg AF, Verdijk MA, Knoers VV, et al. (1994). "Patients with autosomal nephrogenic diabetes insipidus homozygous for mutations in the aquaporin 2 water-channel gene". Am. J. Hum. Genet. 55 (4): 648–52.  
  • Saito F, Sasaki S, Chepelinsky AB, et al. (1994). "Human AQP2 and MIP genes, two members of the MIP family, map within chromosome band 12q13 on the basis of two-color FISH". Cytogenet. Cell Genet. 68 (1–2): 45–8.  
  • Nielsen S, Chou CL, Marples D, et al. (1995). "Vasopressin increases water permeability of kidney collecting duct by inducing translocation of aquaporin-CD water channels to plasma membrane". Proc. Natl. Acad. Sci. U.S.A. 92 (4): 1013–7.  
  • Brown D (2003). "The ins and outs of aquaporin 2 trafficking". Am. J. Physiol. Renal Physiol. 284 (5): F893–901.  
  • Maruyama K, Sugano S (1994). "Oligo-capping: a simple method to replace the cap structure of eukaryotic mRNAs with oligoribonucleotides". Gene 138 (1–2): 171–4.  
  • Deen PM, Verdijk MA, Knoers NV, et al. (1994). "Requirement of human renal water channel aquaporin-2 for vasopressin-dependent concentration of urine". Science 264 (5155): 92–5.  
  • Oksche A, Möller A, Dickson J, et al. (1996). "Two novel mutations in the aquaporin-2 and the vasopressin V2 receptor genes in patients with congenital nephrogenic diabetes insipidus". Hum. Genet. 98 (5): 587–9.  
  • Mulders SM, Knoers NV, Van Lieburg AF, et al. (1997). "New mutations in the AQP2 gene in nephrogenic diabetes insipidus resulting in functional but misrouted water channels". J. Am. Soc. Nephrol. 8 (2): 242–8.  
  • Ma T, Yang B, Umenishi F, Verkman AS (1997). "Closely spaced tandem arrangement of AQP2, AQP5, and AQP6 genes in a 27-kilobase segment at chromosome locus 12q13". Genomics 43 (3): 387–9.  
  • Canfield MC, Tamarappoo BK, Moses AM, et al. (1998). "Identification and characterization of aquaporin-2 water channel mutations causing nephrogenic diabetes insipidus with partial vasopressin response". Hum. Mol. Genet. 6 (11): 1865–71.  
  • Suzuki Y, Yoshitomo-Nakagawa K, Maruyama K, et al. (1997). "Construction and characterization of a full length-enriched and a 5'-end-enriched cDNA library". Gene 200 (1–2): 149–56.  
  • Vargas-Poussou R, Forestier L, Dautzenberg MD, et al. (1998). "Mutations in the vasopressin V2 receptor and aquaporin-2 genes in 12 families with congenital nephrogenic diabetes insipidus". J. Am. Soc. Nephrol. 8 (12): 1855–62.  
  • Kuwahara M (1998). "Aquaporin-2, a vasopressin-sensitive water channel, and nephrogenic diabetes insipidus". Intern. Med. 37 (2): 215–7.  
  • Mulders SM, Bichet DG, Rijss JP, et al. (1998). "An aquaporin-2 water channel mutant which causes autosomal dominant nephrogenic diabetes insipidus is retained in the Golgi complex". J. Clin. Invest. 102 (1): 57–66.  
  • Goji K, Kuwahara M, Gu Y, et al. (1998). "Novel mutations in aquaporin-2 gene in female siblings with nephrogenic diabetes insipidus: evidence of disrupted water channel function". J. Clin. Endocrinol. Metab. 83 (9): 3205–9.  
  • Saito T, Ishikawa S, Ito T, et al. (1999). "Urinary excretion of aquaporin-2 water channel differentiates psychogenic polydipsia from central diabetes insipidus". J. Clin. Endocrinol. Metab. 84 (6): 2235–7.  

External links

  • GeneReviews/NCBI/NIH/UW entry on Nephrogenic Diabetes Insipidus
  • Aquaporin 2 at the US National Library of Medicine Medical Subject Headings (MeSH)