Disease relevance of Aqp1

• Impaired aquaporin and urea transporter expression in rats with adriamycin-induced nephrotic syndrome [1].
• Reverse-transcriptase-PCR revealed very low levels of AQP1 mRNA present in the RBE4 rat brain microvessel endothelial cell line, with no expression detected in primary cultures of rat astrocytes or in the C6 rat glioma cell line [2].
• AIMS: The present study was aimed to determine whether there exists an altered regulation of aquaporin (AQP) water channels in hypertension [3].
• Diminished renal expression of aquaporin water channels in rats with experimental bilateral ureteral obstruction [4].
• It is concluded that decreased aquaporin protein abundance in collecting duct cells is a contributing factor in the increased urine flow seen in moderate post-ischernic acute renal failure [5].

Psychiatry related information on Aqp1

• We tested the possibility that food deprivation might affect the expression and activity of aquaporins (AQP1, 2), thereby impairing renal water reabsorption in the kidney [6].
• The purpose of these studies was to examine the urinary concentrating ability, the expression of kidney water channels [aquaporins (AQP1 to AQP3)], and medullary thick ascending limb (mTAL) Na+-dependent transporters in old but not senescent versus young animals in response to water deprivation [7].

High impact information on Aqp1

• These results provide for the first time evidence for the expression of an aquaporin in skeletal muscle correlated to a specific fiber-type metabolism [8].
• The purpose of this study was to investigate whether escape from vasopressin-induced antidiuresis is associated with altered regulation of any of the known aquaporin water channels [9].
• To investigate a potential role for the AQP1 water channel in development, lung membranes from fetal and perinatal rats were analyzed by immunoblot [10].
• AQP1 was not expressed in airway epithelium, and only occasional alveolar pneumocytes were labeled [10].
• Immunoelectron microscopy revealed AQP1 on both apical and basolateral membranes of endothelial cells [10].

Chemical compound and disease context of Aqp1

• The extensive down-regulation of aquaporin and urea transporter expression may represent an appropriate renal response to the extracellular volume expansion observed in nephrotic syndrome, but may occur at the expense of decreased urinary concentrating and diluting capacity [1].
• Renal denervation decreased the degree of DOCA-salt hypertension, along with lower expression of AQP channels [11].
• CONCLUSIONS: CP-induced polyuria in rats is associated with a significant decrease in the expression of collecting duct (AQP2 and AQP3) and proximal nephron and microvascular (AQP1) water channels in the inner medulla [12].
• We investigated the effects of 7-day aldosterone infusion or oral spironolactone treatment on water balance and aquaporin (AQP) 2 expression in rats with 21 days of lithium-induced nephrogenic diabetes insipidus (Li-NDI) [13].
• Effect of age and testosterone on the vasopressin and aquaporin responses to dehydration in Fischer 344/Brown-Norway F1 rats [14].

Biological context of Aqp1

• Expression of mRNA of AQPs (AQP-1-AQP-4) was studied by semi-quantitative reverse-transcription polymerase chain reaction (RT-PCR) [15].
• Because AQP1 is present on the basolateral cholangiocyte membrane in low amounts, we hypothesized that another AQP must be expressed at this domain to facilitate transbasolateral water movement [16].
• These results suggest that a reduced abundance of AQP water channels in the kidney accounts in part for postobstructive diuresis [4].
• The time course and pattern of AQP4 expression suggests that this aquaporin plays an important role in brain water and K+ homeostasis from the second week of development [17].
• In the efferent ducts and epididymis, specificity exists in cell, region, and tissue distribution with respect to the expression of AQP-1 and -9, and their expression does not appear to be regulated by androgens [18].

Anatomical context of Aqp1

• No mRNA or protein for AQPs 0, 4, 6, and 8 were detectable in epithelial cells, and Aqp1 was detected in whole epididymal samples, but not in epithelial cells [19].
• Evidence against functionally significant aquaporin expression in mitochondria [20].
• Here, we systematically examined the functional consequence of AQP expression in mitochondria by measurement of water and glycerol permeabilities in mitochondrial membrane preparations from rat brain, liver, and kidney and from wild-type versus knock-out mice deficient in AQPs -1, -4, or -8 [20].
• AQP-1 was localized to capillary and arteriole endothelial cells, whereas AQP-2 and -3 circumferentially lined the epithelial cell membranes except for the apical membrane of the epithelial cells adjacent to the lumens of both ureter and bladder [21].
• Reverse-transcriptase-polymerase chain reaction (RT-PCR) and immunocytochemistry showed that AQP1 mRNA and protein are present at very low levels in primary rat brain microvessel endothelial cells, and are up-regulated in passaged cells [2].

Associations of Aqp1 with chemical compounds

• To further specify the primary point of dysregulation of AQP channels that are activated by the arginine vasopressin/cyclic adenosine monophosphate (AVP/cAMP) pathway, different components of adenylyl cyclase complex were separately examined for their cAMP-generating activities [22].
• On the other hand, in the CHG group, expression of AQP-1 and AQP-4 were significantly suppressed, and ultrafiltration volume was lost [15].
• The use of PSL with CHG completely restored the expression of AQP-1 and AQP-4, and peritoneal function improved [15].
• Cisplatin decreases the abundance of aquaporin water channels in rat kidney [23].
• Before the identification of aquaporin (AQP) proteins, vasopressin-regulated "water channels" were identified by freeze-fracture electron microscopy as aggregates or clusters of intramembraneous particles (IMPs) on hormonally stimulated target cell membranes [24].

Co-localisations of Aqp1

• In thymocytes, AQP-1 is present and was shown to colocalize with the plasma membrane receptor tumor necrosis factor receptor-1 (TNF-R1) both before and after the AVD, which suggests that this protein is not proteolytically cleaved and remains on the cell membrane [25].

Regulatory relationships of Aqp1

• In retin, AQP1 is expressed approximately six-fold higher than AQP4, the only other aquaporin expressed [26].
• In cornea, AQP1 is expressed approximately three-fold higher than AQP3 and 2.5 fold higher than AQP5 [26].
• We recently reported that secretin induces the exocytic insertion of functional aquaporin-1 water channels (AQP1) into the apical membrane of cholangiocytes and proposed that this was a key process in ductal bile secretion [16].
• We conclude that the descending thin limbs shift from expressing AQP1 to expressing ClC-K1 some distance before the point where they turn and begin to ascend [27].
• Expression and distribution of aquaporin of collecting duct are regulated by vasopressin V2 receptor in rat kidney [28].

Other interactions of Aqp1

• Analysis of the expression of aquaporin-1 and aquaporin-9 in pig liver tissue: comparison with rat liver tissue [29].
• Expression of AQP1 and AQP4 in rat brain microvessel endothelial cells was investigated in order to determine whether these isoforms were present and, in particular, to examine the hypothesis that brain endothelial expression of AQPs is dynamic and regulated by astrocytic influences [2].
• Neither the expression of AQP1 nor that of AQP3 was significantly affected in the cortex, outer medulla, or inner medulla [22].
• Results from the study demonstrate that water channels AQP1 and AQP6, and the heterotrimeric Go protein are associated with SVs and participate in their swelling [30].
• To specify further the primary point of derangement in the pathway that activates the arginine vasopressin-mediated AQP channels, different components of adenylyl cyclase complex were examined separately [23].

Analytical, diagnostic and therapeutic context of Aqp1

• In passage 4 endothelial cells, AQP1 mRNA levels are reduced by coculture above rat astrocytes, demonstrating that astrocytic influences are important in maintaining the low levels of AQP1 characteristic of the blood-brain barrier endothelium [2].
• In the TZ group, expression of AQP-1 and AQP-4 were significantly enhanced, in parallel with an increment in ultrafiltration volume [15].
• Our results suggest that AQP-1 and AQP-4 may be important factors in water transport in patients undergoing CAPD [15].
• The renal expression of AQP1 to AQP4 proteins was then determined by Western blot and immunohistochemical analyses [4].
• Rats were sacrificed and the kidneys were homogenized at various time points after release of the clamp for semiquantitative immunoblotting of collecting duct aquaporins, as well as the thick ascending limb Na-K-2Cl cotransporter and the proximal tubule water channel, aquaporin-1 [5].

References