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Gene Review

AQP9  -  aquaporin 9

Homo sapiens

Synonyms: AQP-9, Aquaglyceroporin-9, Aquaporin-9, HsT17287, SSC1, ...
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Disease relevance of AQP9


High impact information on AQP9

  • Multifunctional aquaglyceroporins AQP3, AQP7, and AQP9 are permeated by water, glycerol, and some other solutes [3].
  • AQP9 is associated with elevated levels of active Cdc42 and filopodia formation [4]
  • AQP9 plays an active role in neutrophil volume regulation and migration. The display of AQP9 at the plasma membrane depends on AQP9 phosphorylation, which appeared to be regulated through a Rac1-dependent pathway. [5]
  • Similarly, the chronic myeloid leukemia line K562 expressed low levels of AQP9 and was As(2)O(3) insensitive [2].
  • Little AQP7 or AQP9 mRNA was detected by reverse transcription-PCR in either cell line, whereas AQP3 mRNA expression was 2-fold lower in R15 cells than in CL3 cells [6].
  • AQP9 mediates passage of a wide variety of non-charged solutes including carbamides, polyols, purines, and pyrimidines in a phloretin- and mercury-sensitive manner, whereas amino acids, cyclic sugars, Na+, K+, Cl-, and deprotonated monocarboxylates are excluded [7].
  • Unique expression and localization of aquaporin-4 and aquaporin-9 in murine and human neural stem cells and in their glial progeny [8].

Chemical compound and disease context of AQP9

  • Pretreatment of the myeloid leukemia line HL-60 with all-trans retinoic acid (ATRA) up-regulated AQP9, leading to a significantly increased arsenic uptake and As(2)O(3)-induced cytotoxicity on incubation with As(2)O(3), which might explain the synergism between ATRA and As(2)O(3) [2].

Biological context of AQP9

  • The human AQP9 gene is composed of 6 exons and 5 introns distributed over approximately approximately 25 kb [9].
  • The promoter region contains putative tonicity and glucocorticoid-responsive elements, suggesting that AQP9 may be regulated by osmolality and catabolism [9].
  • Here we report a reevaluation of the functional characteristics of hAQP9, its tissue distribution, the structure of its gene, and its chromosomal localization [9].
  • A human homolog (hAQP9) with 76% amino acid sequence identity to rat AQP9 (rAQP9) was described, but its permeability was found to be restricted to water and urea (K. Ishibashi, M. Kuwahara, Y. Gu, Y. Tanaka, F. Marumo, and S. Sasaki. Biochem. Biophys. Res. Commun. 244: 268-274, 1998) [9].
  • Insulin alone had no discernable influence on AQP9 gene expression or its cellular protein levels [10].

Anatomical context of AQP9

  • AQP9 is enriched on the apical (but not basolateral) membrane of nonciliated cells in the efferent duct and principal cells of the epididymis (rat and human) and vas deferens, where it could play a role in fluid reabsorption [11].
  • Intracellular vesicles in epithelial cells along the reproductive tract were generally poorly stained for AQP9 [11].
  • AQP9 was detectable in the epididymis and vas deferens of 1-wk postnatal rats, but its expression was comparable with adult rats only after 3--4 wk [11].
  • Furthermore, the apical membrane distribution of AQP9 was unaffected by microtubule disruption [11].
  • AQP9 is also expressed in epithelial cells of the prostate and coagulating gland where fluid transport across the epithelium is important for secretory activity [11].

Associations of AQP9 with chemical compounds

  • When expressed in Xenopus oocytes, hAQP9 allowed passage of a wide variety of noncharged solutes, including carbamides, polyols, purines, and pyrimidines in a phloretin- and mercurial-sensitive manner [9].
  • 3-beta-diol injections restored AQP9 expression, similar to DHT and estradiol [12].
  • AQP9 displays unique hormonal regulation in the efferent ductules and epididymis, as it is regulated by both estrogen and dihydrotestosterone (DHT) in the efferent ductules, but only by DHT in the initial segment epididymis [12].
  • A molecular analysis indicated lack of expression of aquaporin 9, thus excluding its involvement in the membrane translocation of cisplatin [13].

Other interactions of AQP9


Analytical, diagnostic and therapeutic context of AQP9




  1. Drug uptake and pharmacological modulation of drug sensitivity in leukemia by AQP9. Bhattacharjee, H., Carbrey, J., Rosen, B.P., Mukhopadhyay, R. Biochem. Biophys. Res. Commun. (2004) [Pubmed]
  2. Relationship of expression of aquaglyceroporin 9 with arsenic uptake and sensitivity in leukemia cells. Leung, J., Pang, A., Yuen, W.H., Kwong, Y.L., Tse, E.W. Blood (2007) [Pubmed]
  3. Cellular and molecular biology of the aquaporin water channels. Borgnia, M., Nielsen, S., Engel, A., Agre, P. Annu. Rev. Biochem. (1999) [Pubmed]
  4. Filopodia are induced by aquaporin-9 expression. Loitto, V.M., Huang, C., Sigal, Y.J., Jacobson, K. Exp. Cell. Res. (2007) [Pubmed]
  5. Aquaporin 9 phosphorylation mediates membrane localization and neutrophil polarization. Karlsson, T., Glogauer, M., Ellen, R.P., Loitto, V.M., Magnusson, K.E., Magalhães, M.A. J. Leukoc. Biol. (2011) [Pubmed]
  6. Enhanced expression of multidrug resistance-associated protein 2 and reduced expression of aquaglyceroporin 3 in an arsenic-resistant human cell line. Lee, T.C., Ho, I.C., Lu, W.J., Huang, J.D. J. Biol. Chem. (2006) [Pubmed]
  7. Molecular characterization of a broad selectivity neutral solute channel. Tsukaguchi, H., Shayakul, C., Berger, U.V., Mackenzie, B., Devidas, S., Guggino, W.B., van Hoek, A.N., Hediger, M.A. J. Biol. Chem. (1998) [Pubmed]
  8. Unique expression and localization of aquaporin-4 and aquaporin-9 in murine and human neural stem cells and in their glial progeny. Cavazzin, C., Ferrari, D., Facchetti, F., Russignan, A., Vescovi, A.L., La Porta, C.A., Gritti, A. Glia (2006) [Pubmed]
  9. Functional and molecular characterization of the human neutral solute channel aquaporin-9. Tsukaguchi, H., Weremowicz, S., Morton, C.C., Hediger, M.A. Am. J. Physiol. (1999) [Pubmed]
  10. Identification and characterization of aquaporin-9 (AQP9) in porcine hepatic tissue and hepatocytes in monolayer culture. Caperna, T.J., Shannon, A.E., Richards, M.P., Garrett, W.M., Talbot, N.C. Domest. Anim. Endocrinol. (2007) [Pubmed]
  11. Aquaporin 9 expression along the male reproductive tract. Pastor-Soler, N., Bagnis, C., Sabolic, I., Tyszkowski, R., McKee, M., Van Hoek, A., Breton, S., Brown, D. Biol. Reprod. (2001) [Pubmed]
  12. Effects of 3-beta-diol, an androgen metabolite with intrinsic estrogen-like effects, in modulating the aquaporin-9 expression in the rat efferent ductules. Picciarelli-Lima, P., Oliveira, A.G., Reis, A.M., Kalapothakis, E., Mahecha, G.A., Hess, R.A., Oliveira, C.A. Reprod. Biol. Endocrinol. (2006) [Pubmed]
  13. Electron microscopy analysis of early localization of cisplatin in ovarian carcinoma cells. Beretta, G.L., Righetti, S.C., Lombardi, L., Zunino, F., Perego, P. Ultrastructural pathology. (2002) [Pubmed]
  14. Lentiviral transduction of human postnatal skeletal (stromal, mesenchymal) stem cells: in vivo transplantation and gene silencing. Piersanti, S., Sacchetti, B., Funari, A., Di Cesare, S., Bonci, D., Cherubini, G., Peschle, C., Riminucci, M., Bianco, P., Saggio, I. Calcif. Tissue Int. (2006) [Pubmed]
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