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Gene Review

Aqp8  -  aquaporin 8

Rattus norvegicus

Synonyms: AQP-8, Aquaporin-8
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Disease relevance of Aqp8


High impact information on Aqp8

  • Furthermore, exposure of isolated hepatocytes to glucagon, a choleretic agonist, significantly increased the expression of AQP8 associated with the apical microdomain fractions but had no effect on AQP9 expression in the basolateral microdomain fractions [3].
  • We recently demonstrated that mixed plasma membrane fractions isolated from rat hepatocyte couplets contain lipid microdomains ("rafts") enriched in cholesterol and sphingolipids and AQP8 and 9 [3].
  • In nontransfected NMCs, the transcellular water flow, P(f), value was relatively high (i.e., 16.4 +/- 3.2 microm/sec) and likely was a reflection of endogenous expression of AQP1 and AQP8 [4].
  • Confocal immunofluorescence microscopy in cultured hepatocytes confirmed the glucagon-induced redistribution of AQP8 from intracellular vesicles to plasma membrane [5].
  • The inhibitors of protein kinase A, H-89, and PKI, as well as the microtubule blocker colchicine, prevented the glucagon effect on both AQP8 redistribution to hepatocyte surface and cell membrane water permeability [5].

Biological context of Aqp8


Anatomical context of Aqp8


Associations of Aqp8 with chemical compounds


Regulatory relationships of Aqp8


Other interactions of Aqp8

  • We found transcripts of three of 10 aquaporins in hepatocytes (aquaporin 8 aquaporin 9 > aquaporin 0) by reverse transcription-polymerase chain reaction and quantitative ribonuclease protection assays; immunohistochemistry confirmed the presence of these three proteins in liver [12].
  • The ontogeny and distribution of AQP7 and AQP8 in rat testis suggest involvement in major physiologic changes in testis development and spermatogenesis [11].
  • In the testis of normal adult animals, AQP-8 was expressed exclusively in Sertoli cells, while AQP-9 outlined Leydig cells [17].
  • Here, we show the presence of a member of the aquaporin family of water channels, AQP8, and demonstrate the strikingly high water permeability (Pf) characterizing the rat liver IMM [8].
  • AQP6 is present in intracellular vesicles in collecting duct intercalated cells and AQP8 are present intracellularly at low abundance in proximal tubules and collecting duct principal cells but the physiological function of these 2 channels remain undefined [18].

Analytical, diagnostic and therapeutic context of Aqp8


  1. Rat hepatocyte aquaporin-8 water channels are down-regulated in extrahepatic cholestasis. Carreras, F.I., Gradilone, S.A., Mazzone, A., García, F., Huang, B.Q., Ochoa, J.E., Tietz, P.S., Larusso, N.F., Calamita, G., Marinelli, R.A. Hepatology (2003) [Pubmed]
  2. Canalicular membrane localization of hepatocyte aquaporin-8 is preserved in estradiol-17beta-D-glucuronide-induced cholestasis. Mottino, A.D., Carreras, F.I., Gradilone, S.A., Marinelli, R.A., Vore, M. J. Hepatol. (2006) [Pubmed]
  3. Isolation and characterization of lipid microdomains from apical and basolateral plasma membranes of rat hepatocytes. Mazzone, A., Tietz, P., Jefferson, J., Pagano, R., LaRusso, N.F. Hepatology (2006) [Pubmed]
  4. AQP4 transfected into mouse cholangiocytes promotes water transport in biliary epithelia. Splinter, P.L., Masyuk, A.I., Marinelli, R.A., LaRusso, N.F. Hepatology (2004) [Pubmed]
  5. Glucagon induces the plasma membrane insertion of functional aquaporin-8 water channels in isolated rat hepatocytes. Gradilone, S.A., García, F., Huebert, R.C., Tietz, P.S., Larocca, M.C., Kierbel, A., Carreras, F.I., Larusso, N.F., Marinelli, R.A. Hepatology (2003) [Pubmed]
  6. Aquaporin-8 is involved in water transport in isolated superficial colonocytes from rat proximal colon. Laforenza, U., Cova, E., Gastaldi, G., Tritto, S., Grazioli, M., LaRusso, N.F., Splinter, P.L., D'Adamo, P., Tosco, M., Ventura, U. J. Nutr. (2005) [Pubmed]
  7. Cloning and functional expression of a second new aquaporin abundantly expressed in testis. Ishibashi, K., Kuwahara, M., Kageyama, Y., Tohsaka, A., Marumo, F., Sasaki, S. Biochem. Biophys. Res. Commun. (1997) [Pubmed]
  8. The inner mitochondrial membrane has aquaporin-8 water channels and is highly permeable to water. Calamita, G., Ferri, D., Gena, P., Liquori, G.E., Cavalier, A., Thomas, D., Svelto, M. J. Biol. Chem. (2005) [Pubmed]
  9. Expression and immunolocalization of the aquaporin-8 water channel in rat gastrointestinal tract. Calamita, G., Mazzone, A., Bizzoca, A., Cavalier, A., Cassano, G., Thomas, D., Svelto, M. Eur. J. Cell Biol. (2001) [Pubmed]
  10. Evidence against functionally significant aquaporin expression in mitochondria. Yang, B., Zhao, D., Verkman, A.S. J. Biol. Chem. (2006) [Pubmed]
  11. Possible involvement of aquaporin-7 and -8 in rat testis development and spermatogenesis. Calamita, G., Mazzone, A., Bizzoca, A., Svelto, M. Biochem. Biophys. Res. Commun. (2001) [Pubmed]
  12. Expression and localization of aquaporin water channels in rat hepatocytes. Evidence for a role in canalicular bile secretion. Huebert, R.C., Splinter, P.L., Garcia, F., Marinelli, R.A., LaRusso, N.F. J. Biol. Chem. (2002) [Pubmed]
  13. The water channel aquaporin-8 is mainly intracellular in rat hepatocytes, and its plasma membrane insertion is stimulated by cyclic AMP. García, F., Kierbel, A., Larocca, M.C., Gradilone, S.A., Splinter, P., LaRusso, N.F., Marinelli, R.A. J. Biol. Chem. (2001) [Pubmed]
  14. Expression and immunolocalization of aquaporin water channels in rat exocrine pancreas. Hurley, P.T., Ferguson, C.J., Kwon, T.H., Andersen, M.L., Norman, A.G., Steward, M.C., Nielsen, S., Case, R.M. Am. J. Physiol. Gastrointest. Liver Physiol. (2001) [Pubmed]
  15. Expression and localization of aquaporins in rat gastrointestinal tract. Koyama, Y., Yamamoto, T., Tani, T., Nihei, K., Kondo, D., Funaki, H., Yaoita, E., Kawasaki, K., Sato, N., Hatakeyama, K., Kihara, I. Am. J. Physiol. (1999) [Pubmed]
  16. Cholera toxin induces expression of ion channels and carriers in rat small intestinal mucosa. Flach, C.F., Lange, S., Jennische, E., Lönnroth, I. FEBS Lett. (2004) [Pubmed]
  17. Expression and regulation of aquaporins 1, 8, and 9 in the testis, efferent ducts, and epididymis of adult rats and during postnatal development. Badran, H.H., Hermo, L.S. J. Androl. (2002) [Pubmed]
  18. Physiology and pathophysiology of renal aquaporins. Kwon, T.H., Hager, H., Nejsum, L.N., Andersen, M.L., Frøkiaer, J., Nielsen, S. Semin. Nephrol. (2001) [Pubmed]
  19. Expression and localization of the aquaporin-8 water channel in rat testis. Calamita, G., Mazzone, A., Cho, Y.S., Valenti, G., Svelto, M. Biol. Reprod. (2001) [Pubmed]
  20. Immunolocalization of aquaporin-8 in rat kidney, gastrointestinal tract, testis, and airways. Elkjaer, M.L., Nejsum, L.N., Gresz, V., Kwon, T.H., Jensen, U.B., Frøkiaer, J., Nielsen, S. Am. J. Physiol. Renal Physiol. (2001) [Pubmed]
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