Disease relevance of Aqp9

• We hypothesize that the complement of mitochondrial AQP9 in dopaminergic neurons may relate to the vulnerability of these neurons in Parkinson's disease [1].

High impact information on Aqp9

• 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 [2].
• Immunoblots of subcellular fractions of hepatocytes showed enrichment of aquaporins 0 and 8 in microsomes and canalicular plasma membranes; aquaporin 9 was enriched only in basolateral plasma membranes [3].
• Our data show that, whereas AQP9 is the main AQP of the epididymis, the mRNA specific for Aqp2, 5, 7, and 11 are also expressed in epididymal epithelial cells [4].
• AQP9 is abundantly expressed in the efferent ducts, the epididymis, and the vas deferens, where it could represent an important apical pathway for transmembrane water and solute movement [4].
• Staining of AQP5, -8, and -9 was lost after ovariectomy, and only AQP9 immunoreactivity was restored after estradiol and/or progesterone treatments [5].

Biological context of Aqp9

• Levels of AQP9 varied along the estrous cycle with their highest levels during proestrus and estrus [5].
• We found that aquaporin-9 transcript (AQP9) is present in proestrus oocytes but not in estrus oocytes [6].
• These results suggest that signal transduction via PKA may play important roles in regulating the expression of AQP5 and AQP9, and the effect on AQP9 may be mediated by some factors induced by dbcAMP [7].
• This isoform is likely to correspond to a new AQP9 mRNA that is obtained by alternative splicing and has a shorter ORF than the liver isoform [1].
• All these findings show a unique tissue distribution of AQP9 compared to the other known aquaporins [8].

Anatomical context of Aqp9

• The distribution of AQP5 and -8 was mainly cytoplasmic, whereas we confirmed, by confocal microscopy, that AQP9 localized to the apical plasma membrane [5].
• Regulation of the immunoexpression of aquaporin 9 by ovarian hormones in the rat oviductal epithelium [5].
• Antibody to AQP-9 reacted strongly with small ductules peripheral to the liver lobules, but only weakly with the bile ducts of the portal space [9].
• Immunofluorescence of hepatocyte couplets confirmed the intracellular/canalicular localization of aquaporins 0 and 8 and the basolateral localization of aquaporin 9 [3].
• DHT, but not oestradiol, modulated AQP9 expression in the initial segment of the epididymis [10].

Associations of Aqp9 with chemical compounds

• Interestingly, progesterone administration after progesterone priming also induced AQP9 expression but without a change in mRNA levels [5].
• The recovery of AQP9 reactivity after ovariectomy correlated with increased mRNA and protein levels after treatment with estradiol alone or progesterone administration after estradiol priming [5].
• These results indicate that steroid hormones regulate AQP9 expression at the mRNA and protein level and that other ovarian signals are involved in the expression of AQP5 and -8 [5].
• DHT (5alpha-dihydrotestosterone) also modulated AQP9 in efferent ductules [10].
• In addition, castrated adult rats showed lower levels of epididymal AQP9 compared with adult controls, whereas systemic testosterone treatment of castrated adult rats induced a recovery of the expression of AQP9 to control levels [11].

Other interactions of Aqp9

• Analysis of the expression of aquaporin-1 and aquaporin-9 in pig liver tissue: comparison with rat liver tissue [9].
• In the latter structures, the AQP9 immunopositive mitochondria were located in neurons that were also immunopositive for tyrosine hydroxylase, as demonstrated by double labeling immunogold electron microscopy [1].

Analytical, diagnostic and therapeutic context of Aqp9

• To understand better the regulation of AQP1 and AQP9, we investigated their expression in rat efferent ductules and initial segment of the epididymis after treatment with the pure antioestrogen ICI 182,780 or bilateral efferent duct ligation, or castration, followed by hormone replacement [10].
• With the aim of understanding the pathophysiological role of AQP9, we performed an extensive analysis by Western blotting, RT-PCR, and immunolocalization in rat tissues [8].
• Radioimmunoassay for aquaporin-9 [12].
• The aim of this study was to identify the distribution of aquaporin-9 by immunohistochemistry in rat tissues using specific antipeptide antiserum which we recently produced [13].

References