Disease relevance of Aqp3

• Dehydration resulted in 160-200% increases of AQP-3 signal and 24-49% increases of AQP-2 signal but no change in AQP-1 signal on immunoblots of homogenates of ureters and bladders [1].
• Compensatory increase in AQP2, p-AQP2, and AQP3 expression in rats with diabetes mellitus [2].
• These experiments demonstrated that adriamycin-induced nephrotic syndrome is associated with marked decreases in expression of aquaporin-2, aquaporin-3, aquaporin-4, and the vasopressin-regulated urea transporter in renal inner medulla, indicative of a suppression of the capacity for water and urea absorption by the inner medullary collecting duct [3].
• Reduced renal expression of AQP2, p-AQP2 and AQP3 in haemorrhagic shock-induced acute renal failure [4].
• In conclusion, severe downregulation of AQP2 and AQP3 appears to be important for the development of Li-induced polyuria [5].

High impact information on Aqp3

• In contrast, immunoblotting demonstrated a lack of an increase in expression of AQP1 and AQP3 water channel expression, indicating that the effect on AQP2 was selective [6].
• The present study demonstrates the existence of an additional water channel, AQP3, in epithelial cells of the medullary collecting duct [7].
• AQP3 did not permit passage of monovalent ions (Na, K, Cl); however, it is slightly permeable to urea [7].
• Injection of the complementary RNA of AQP3 into Xenopus oocytes markedly increased the osmotic water permeability [7].
• AQP3 has amino acid sequence identity with major intrinsic protein (MIP) family proteins including AQP-channel-forming integral membrane protein, AQP-collecting duct, MIP, AQP-gamma tonoplast intrinsic protein, nodulin 26, and glycerol facilitator (33-42%) [8].

Chemical compound and disease context of Aqp3

• These results indicate that age-related polyuria is associated with a downregulation of AQP2 and AQP3 expression in the medullary collecting duct, which is independent of vasopressin-mediated cAMP accumulation [9].
• Lithium treatment is associated with development of nephrogenic diabetes insipidus, caused in part by downregulation of collecting duct aquaporin-2 (AQP2) and AQP3 expression [10].
• Treatment with the cAMP-PDE inhibitors rolipram and milrinone in combination (inhibiting PDE IV and PDE III isoenzymes) at day 2 and onward completely prevented the hypercalcemia-induced downregulation of AQP2 and AQP3 (but not AQP1) and completely prevented the development of polyuria [11].

Biological context of Aqp3

• Our results suggest that AQP3 is expressed not only in large airways, but also in bronchioles, and is related to water movement in pulmonary oedema [12].
• Semiquantitative immunoblotting revealed that aldosterone deficiency was associated with a dramatic downregulation of AQP3 abundance [13].
• Up-regulation of cochlear aquaporin-3 mRNA expression after intra-endolymphatic sac application of dexamethasone [14].
• These findings suggest that the intra-endolymphatic sac steroids could make regulatory effects on the inner ear AQP-3 expression via vestibular aqueduct and modulate the homeostasis of endolymphatic fluids, encouraging the possibility that the endolymphatic sac could be a therapeutic window for the inner ear disease [14].
• In addition, they suggest that AQP3 gene expression may depend on the presence of luminal contents [15].

Anatomical context of Aqp3

• No expression of AQP-2 and AQP-3 was seen in the peritoneum [16].
• Consistent with this, immunocytochemistry and immunoelectron microscopy revealed a marked decrease in AQP3 labeling in the basolateral plasma membranes of collecting duct principal cells [13].
• Only AQP-3 mRNA expression in the ipsilateral cochlea was significantly up-regulated in comparison with controls and the up-regulation was demonstrated both in dose-dependent and time-dependent manners [14].
• In contrast, AQP3 is present in basal cells of tracheal and nasopharyngeal epithelium and is abundant in basolateral membranes of surface epithelial cells of nasal conchus [17].
• AQP3 mRNA was expressed abundantly in kidney medulla and colon [8].

Associations of Aqp3 with chemical compounds

• Semi-quantitative RT-PCR showed that AQP3 mRNA in the thiourea group rose significantly, peaking at around 4-8 h [12].
• In conclusion, the results uniformly demonstrate that aldosterone regulates AQP3 abundance independently of Na intake [13].
• Under these circumstances, there were no changes in AQP3 or AQP2 abundance, although the level of the thiazide-sensitive Na-Cl cotransporter was decreased [13].
• Whole kidney abundance of AQP3, the bumetanide-sensitive Na-K-2Cl cotransporter (NKCC2), and gamma-ENaC (85-kDa band) correlated most strongly with blood glucose in study 3 [18].
• The protein expression of AQP1 as well as that of AQP3 was also decreased in the cortex by treatment with the highest dose of gentamicin [19].

Other interactions of Aqp3

• Aquaporin-2 and aquaporin-3 expression was also markedly diminished in the renal cortex, indicating that the effect is not limited to the inner medullary collecting duct [3].
• AQP3 and AQP4 mRNA expression was significantly found at birth but was not changed remarkably thereafter [20].
• Additional cDNA arrays revealed that several transcripts that were increased in abundance after 72 h of dDAVP were also increased after 4 h, including casein kinase IIbeta, beta-ENaC, aquaporin-3, UT-A, and syntaxin 2 [21].

Analytical, diagnostic and therapeutic context of Aqp3

• Northern blot analysis showed a single transcript for AQP3 of approximately 1.9 kb present in the renal medulla, predominantly in the inner medulla [7].
• Immunoblot analysis showed that glycosylated AQP3 protein was increased 4-10 h after treatment [12].
• Osmotic water permeability of Xenopus oocytes measured by videomicroscopy was 10-fold higher in oocytes injected with AQP3 transcript than with water-injected oocytes [8].
• Consistent with this, immunohistochemistry demonstrated reduced AQP3 immunolabeling along the entire collecting duct [11].
• Examination of orchidectomized rats revealed that AQP-3 expression was abolished over basal cells and that it was greatly diminished after efferent duct ligation [22].

References