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Genetically encoded reporters for magnetic resonance imaging (MRI) offer a valuable technology for making molecular-scale measurements of biological processes within living organisms with high anatomical resolution and whole-organ coverage without relying on ionizing radiation. However, most MRI reporters rely on synthetic contrast agents, typically paramagnetic metals and metal complexes, which often need to be supplemented exogenously to create optimal contrast. To eliminate the need for synthetic contrast agents, we previously introduced aquaporin-1, a mammalian water channel, as a new reporter gene for the fully autonomous detection of genetically labeled cells using diffusion-weighted MRI. In this study, we aimed to expand the toolbox of diffusion-based genetic reporters by modulating aquaporin membrane trafficking and harnessing the evolutionary diversity of water channels across species. We identified a number of new water channels that functioned as diffusion-weighted reporter genes. In addition, we show that loss-of-function variants of yeast and human aquaporins can be leveraged to design first-in-class diffusion-based sensors for detecting the activity of a model protease within living cells., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 The Authors. Published by Elsevier Inc. All rights reserved.)

Background: Recently, some studies have suggested a link between AQP1 and cancer progression., Aims: The aim of the present study was to investigate the influence of AQP1 on the clinicopathology and prognosis of intrahepatic cholangiocarcinoma (ICC) patients., Methods: We retrospectively detected the expression of AQP1 protein in 307 patients with ICC who underwent partial hepatectomy. Western blot analysis was used to detect AQP1 protein levels in stable AQP1 overexpression and knockdown cell lines. The influence of AQP1 on the invasion and metastasis ability of ICC cells was assessed by wound-healing and Transwell assays in vitro as well as by a splenic liver metastasis model in vivo., Results: Positive membranous AQP1 expression was identified in 34.2% (105/307) of the ICC specimens. Survival data revealed that positive AQP1 expression was significantly associated with favourable disease-free survival (DFS) and overall survival (OS) (p = 0.0290 and p = 0003, respectively). Moreover, high AQP1 expression inhibited the invasion and migration of ICC cells in vitro as well as inhibited liver metastasis in nude mice. Mechanistically, high AQP1 expression in ICC cells increased the levels of E-cadherin but decreased the levels of the Snail transcription factor., Conclusions: AQP1 expression is associated with a favourable prognosis in ICC patients. AQP1 inhibits ICC cell invasion, metastasis, and epithelial-mesenchymal transition (EMT) through downregulation of Snail expression., Competing Interests: Conflict of interest We confirm no potential conflict of interest or financial dependence regarding this study., (Copyright © 2022 The Author(s). Published by Elsevier Ltd.. All rights reserved.)

Aquaporin (AQP) water channels facilitate water transport across cellular membranes and are essential in regulation of body water balance. Moreover, several AQPs are overexpressed or ectopically expressed in breast cancer. Interestingly, several in vitro studies have suggested that AQPs can affect the response to conventional anticancer chemotherapies. Therefore, we took a systematic approach to test how AQP1, AQP3 and AQP5, which are often over-/ectopically expressed in breast cancer, affect total viability of 3-dimensional (3D) breast cancer cell spheroids when treated with the conventional anticancer chemotherapies Cisplatin, 5-Fluorouracil (5-FU) and Doxorubicin, a Combination of the three drugs as well as the Combination plus the Ras inhibitor Salirasib. Total viability of spheroids overexpressing AQP1 were decreased by all treatments except for 5-FU, which increased total viability by 20% compared to DMSO treated controls. All treatments reduced viability of spheroids overexpressing AQP3. In contrast, only Doxorubicin, Combination and Combination + Salirasib reduced total viability of spheroids overexpressing AQP5. Thus, this study supports a significant role of AQPs in the response to conventional chemotherapies. Evaluating the role of individual proteins that contribute to resistance to chemotherapies is essential in advancing personalized medicine in breast carcinomas., Competing Interests: Declaration of competing interest The authors declare no conflict of interest., (Copyright © 2022 The Authors. Published by Elsevier Inc. All rights reserved.)

Introduction: The uterus and placenta transport water during pregnancy recognition signaling, conceptus implantation, and placental development/placentation. This is likely influenced by aquaporins (AQPs) in the reproductive tract. This study determined mRNA and cell-type specific expression of AQP 1, 5, 8, and 9 proteins in the porcine uterus and placenta., Methods: Porcine uteri and Chorioallantois were subjected to real-time PCR and immunofluorescence microscopy., Results: AQP1 mRNA was maximal by Day 25 in endometrium and remained stable thereafter. AQP1 mRNA did not change in chorioallantois. AQP1 protein localized to erythrocytes and endothelium of the endometrium and allantois, and to smooth muscle of the myometrium. AQP5 protein localized to apical and lateral surfaces of the chorionic epithelia of areolae, but mRNA did not change in chorioallantois. AQP8 mRNA was high in the endometrium from Days 15 through 60 of gestation, and protein localized to multiple cell types within the endometrium and chorioallantois. AQP9 mRNA was highest in the endometrium on Days 10, 12 and 25, but did not change in the chorioallantois. AQP9 protein localized to the apical surface of endometrial luminal epithelial cells during early pregnancy, with a shift towards the basal surface later. AQP9 protein was observed in the allantoic epithelium., Discussion: Results reveal pigs can potentially use AQP1, AQP5, AQP8, and AQP9 to transport water from the endometrial bloodstream to the allantoic bloodstream or allantoic fluid. The reverse is also possible and may explain the mechanism for changing volumes of allantoic fluid and hydration of allantoic connective tissues during pregnancy., (Copyright © 2022 Elsevier Ltd. All rights reserved.)

Aquaporins play a crucial role in water homeostasis in the human body, and recently the physiological importance of aquaporins as glycerol channels have been demonstrated. The aquaglyceroporins (AQP3, AQP7, AQP9 and AQP10) represent key glycerol channels, enabling glycerol flux across the membranes of cells. Adipocytes are the major source of glycerol and during lipolysis, glycerol is released to be metabolized by other tissues through a well-orchestrated process. Here we show that both AQP3 and AQP7 bind to the lipid droplet protein perilipin 1 (PLIN1), suggesting that PLIN1 is involved in the coordination of the subcellular translocation of aquaglyceroporins in human adipocytes. Moreover, in addition to aquaglyceroporins, we discovered by transcriptome sequencing that AQP1 is expressed in human primary adipocytes. AQP1 is mainly a water channel and thus is thought to be involved in the response to hyper-osmotic stress by efflux of water during hyperglycemia. Thus, this data suggests a contribution of both orthodox aquaporin and aquaglyceroporin in human adipocytes to maintain the homeostasis of glycerol and water during fasting and feeding., (Copyright © 2021 The Authors. Published by Elsevier B.V. All rights reserved.)

Aquaporin's (AQPs) are the major superfamily of small integral membrane proteins that facilitates transportation of water, urea, ammonia, glycerol and ions across biological cell membranes. Despite of recent advancements made in understanding the biology of Aquaporin's, only few isoforms of aquaporin 1 (AQP1) some of the teleost fish species have been characterized at molecular scale. In this study, we made an attempt to elucidate the molecular mechanism of water transportation in AQP1 from walking catfish (Clarias batrachus), a model species capable of breathing in air and inhabits in challenging environments. Using state-of-the-art computational modelling and all-atoms molecular dynamics simulation, we explored the structural dynamics of full-length aquaporin 1 from walking catfish (CbAQP1) in lipid mimetic bilayers. Unlike AQP1 of human and bovine, structural ensembles of CbAQP1 from MD revealed discrete positioning of pore lining residues at the intracellular end. Snapshots from MD simulation displayed differential dynamics of aromatic/arginine (ar/R) filter and extracellular loop C bridging transmembrane (TM) helix H3 and H4. Distinct conformation of large extracellular loops, loop bridging TM2 domain and HB helix along with positioning of selectivity filter lining residues controls the permeability of water across the bilayer. Moreover, the identified unique and conserved lipid binding sites with 100% lipid occupancy signifies lipid mediated structural dynamics of CbAQP1. All-together, this is the first ever report on structural-dynamics of aquaporin 1 in walking catfish which will be useful to understand the molecular basis of transportation of water and other small molecules under varying degree of hyperosmotic environment., (Copyright © 2021. Published by Elsevier B.V.)

The Leishmania aquaglyceroporin 1 (AQP1) plays an important role in osmoregulation and antimony (Sb) uptake, being determinant for resistance to antimony. We have previously demonstrated that G133D mutation on L. guyanensis AQP1 (LgAQP1) leads to reduced Sb uptake. Here, we investigated the effects of G133D mutation on LgAQP1 structure, associated with Sb uptake and alterations in osmoregulation capacity. High confidence molecular models of wild-type LgAQP1 as well as the LgAQP1::G133D mutant were constructed and optimized via comparative homology modeling. Computational methods from the mCSM platform were used to evaluate the effects on protein stability and on its ability to bind to glycerol. Functional validation of the disruptive effect of the mutation on LgAQP1 was done by challenging the parasites with hypo-osmotic chock. Glycine 133 is on transmembrane helix 3, buried in the membrane in both open and closed conformation. G133D mutation was predicted to be highly destabilizing, as it alters the helical bundling arrangement in order to accommodate the aspartic acid side chain. The shift in helices also resulted in fewer favorable contacts with glycerol in the channel, which would explain the reduced affinity for similar small molecules as SbO 3 . Under hypo-osmotic condition, L. guyanensis AQP1G133D presented a 3-fold increase in cellular volume and pronounced delay to recover osmosis homeostasis when compared to the wild-type, a profile that was enhanced in LgAQP1-/- mutants. In conclusion, G133D is a highly disruptive mutation that will destabilize the monomer, compromise tetramer formation and alter pore conformation, leading to reduced Sb uptake and deficient osmoregulation., (Copyright © 2021 Elsevier B.V. All rights reserved.)

Background: Aquaporins are membrane water channel proteins that are expressed in the epithelium and endothelium. Their primary function is to control the flow of water in the membranes of the cells., Objective: In this study, we investigated whether there is increased expression of aquaporin-1 in the tunica vaginalis of hydrocele patients in childhood that do not regress spontaneously an whether it has an effect on the etiology of hydrocele., Study Design: Boys who were diagnosed with hydrocele and scheduled for surgery were included and formed the hydrocele group. Boys in the same age range who underwent surgery for inguinal hernia or undescended testicles were included as a control group. Aquaporin-1 expression was evaluated by immunohistochemical examination of capillaries in tissue samples taken from the tunica vaginalis during the operation. Aquaporin-1-positive vessels were counted by selecting 5 unrelated areas with the highest vascular density, and the average number of vessels was calculated for each case., Results: A total of 48 male patients were included in the study. Of these, 27 constituted the hydrocele group (mean age 3.51 ± 2.59 years), and 21 constituted the control group (inguinal hernia, n = 17; undescended testicle, n = 4) (mean age 3.95 ± 3.80 years). The mean ages of both groups were statistically similar (p = 0.32). The mean numbers of aquaporin-1-positive vessels at the capillaries in the tunica vaginalis of the patients were 20.74 ± 7.10 in hydrocele group and 17.23 ± 4.07 in the control group. The expression of aquaporin-1 in the hydrocele group was significantly higher (p = 0.037)., Discussion: It was shown that aquaporin-1 expression was higher in adult cases with hydrocele. Also an increase in aquaporin-1 expression was detected in tunica vaginalis of children with hydrocele in our study., Conclusion: It was thought that aquaporin-1 overexpression may play a role in non-communicating hydroceles in children., Competing Interests: Conflicts of interest The authors declare no conflicts of interest., (Copyright © 2021 Journal of Pediatric Urology Company. Published by Elsevier Ltd. All rights reserved.)

Aquaporin 1 (AQP1) is the archetype of all aquaporins and involved in rapid cellular water fluxes and cell volume regulation., An Objective: This study was conducted for the investigation of AQP1 expression in normal testicular tissues and those with I/R injury in a rat model., Study Design: A TT rat model was established using male Wister rats (4 weeks old, 180-220 g), and AQP1 distribution in the testicular tissues was detected by immunohistochemistry. The wet/dry (W/D) weight ratios of the testes were determined at 12 h, 24 h, 36 h, 48 h, or 5 days after the establishment of the TT model. At each time point, pathological sections were prepared and the mRNA and protein expression levels of AQP1 were determined by RT-qPCR and Western blotting, respectively., Results: Immunohistochemical staining indicated that AQP1 distributes in testicular vascular endothelial cells and interstitial connective tissues. The testicular edema was observed 12 and 24 h after TT, as indicated by the increase in wet/dry weight ratio and pathological changes, such as enlarged testicular interstitium, atrophy of spermatogenic tubules, and epineurium tubule exfoliation. Increase in the expression levels of Aqp1 mRNA and AQP1 protein levels peaked at 24 h. Edema was alleviated at 36 and 48 h, as manifested by the gradual thinning of the spermatogenic tubules epithelium with narrowed interstitium and weakened inflammatory cell infiltration. Meanwhile, the mRNA and protein levels of AQP1 dramatically decreased. At 5 days after TT, edema was nearly absent, and the mRNA and protein levels of AQP1 were restored to basal levels., Discussion: Testicular torsion increases AQP1 expression and W/D ratios in testis tissues. The upregulation of AQP1 expression and decline in AQP1 level are consistent to the development and alleviation of edema in testis tissues that underwent testicular torsion., Conclusion: Changes in AQP1 expression were consistent with edema severity in the testes, indicating a close relationship between the expression of AQP1 and the extent of edema in testicular I/R., (Copyright © 2020 Journal of Pediatric Urology Company. Published by Elsevier Ltd. All rights reserved.)

Background: Administration of antenatal steroids is standard of care for women assessed to be at imminent risk of preterm delivery. There is a marked variation in antenatal steroid dosing strategy, selection for treatment criteria, and agent choice worldwide. This, combined with very limited optimization of antenatal steroid use per se, means that treatment efficacy is highly variable, and the rate of respiratory distress syndrome is decreased to perhaps as low as 40%. In some cases, antenatal steroid use is associated with limited benefit and potential harm., Objective: We hypothesized that individual differences in maternofetal steroid exposure would contribute to observed variability in antenatal steroid treatment efficacy. Using a chronically catheterized sheep model of pregnancy, we aimed to explore the relationship between maternofetal steroid exposure and antenatal steroid treatment efficacy as determined by functional lung maturation in preterm lambs undergoing ventilation., Study Design: Ewes carrying a single fetus underwent surgery to catheterize a fetal and maternal jugular vein at 119 days' gestation. Animals recovered for 24 hours before being randomized to either (1) a single maternal intramuscular injection of 2 mL saline (negative control group, n=10) or (2) a single maternal intramuscular injection of 0.25 mg/kg betamethasone phosphate plus acetate (antenatal steroid group, n=20). Serial maternal and fetal plasma samples were collected from each animal after 48 hours before fetuses were delivered and ventilated for 30 minutes. Total and free plasma betamethasone concentration was measured by mass spectrometry. Fetal lung tissue was collected for analysis using quantitative polymerase chain reaction., Results: One animal from the control group and one animal from the antenatal steroid group did not complete their treatment protocol and were removed from analyses. Animals in the antenatal steroid group were divided into a responder subgroup (n=12/19) and a nonresponder subgroup (n=7/19) using a cutoff of partial pressure of arterial CO 2 at 30-minute ventilation within 2 standard deviations of the mean value from saline-treated negative control group animals. Although antenatal steroid improved fetal lung maturation in the undivided antenatal steroid group and in the responder subgroup both physiologically (blood gas- and ventilation-related data) and biochemically (messenger ribonucleic acid expression related to fetal lung maturation), these values did not improve relative to saline-treated control group animals in the antenatal steroid nonresponder subgroup. No differences in betamethasone distribution, clearance, or protein binding were identified between the antenatal steroid responder and nonresponder subgroups., Conclusion: This study correlated individual maternofetal steroid exposures with preterm lung maturation as determined by pulmonary ventilation. Herein, approximately 40% of preterm lambs exposed to antenatal steroids had lung maturation that was not significantly different to saline-treated control group animals. These nonresponsive animals received maternal and fetal betamethasone exposures identical to animals that had a significant improvement in functional lung maturation. These data suggest that the efficacy of antenatal steroid therapy is not solely determined by maternofetal drug levels and that individual fetal or maternal factors may play a role in determining treatment outcomes in response to glucocorticoid signaling., (Copyright © 2020 Elsevier Inc. All rights reserved.)

Circadian rhythms are a fundamental biological phenomena that control various physiological functions. The suprachiasmatic nucleus (SCN) is a master clock that integrates various peripheral clocks. Recently, the choroid plexus (CP) was reported to be one such peripheral clock, a circadian oscillator that might conversely affect the SCN. Hence, the principle aim of our study was to unravel the circadian oscillator within the CP. Quantitative PCR against rPer1, rPer2, and rBmal1 showed that CP in the lateral ventricle (CP-LV) and fourth ventricle (CP-4V) has a robust circadian oscillator. The phases of the CP oscillator are between those of the pineal gland (PG) and SCN. Bioluminescence monitoring of explants showed that the intrinsic circadian period of CP-LV and CP-4V was approximately 21 h, which is shorter than SCN and PG. It is possible that interaction between oscillators of the CP-LV, CP-4V, PG, and SCN ensures the SCN adopts a stable 24 h rhythm, with each of the regions having an intrinsic oscillator with different phases and periods. In situ hybridization analysis revealed that dusk-to-dawn variation of rPer2 expression was found in epithelial cells of the CP only. Furthermore, the CP circadian oscillator might control cerebrospinal fluid secretion. However, no dusk-to-dawn variation in expression of the water channel, aquaporin 1, was observed. Further investigations are needed to clarify the involvement of circadian rhythm on CP., Competing Interests: Declaration of competing interests The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2020 The Author(s). Published by Elsevier Inc. All rights reserved.)

Cholangiocytes are the epithelial cells that line bile ducts, and ductal plate malformation is a developmental anomaly of bile ducts that causes severe congenital biliary disorders. However, because of a lack of specific marker genes, methods for the stepwise differentiation and isolation of human induced pluripotent stem cell (hiPSC)-derived cholangiocyte progenitors at ductal plate stages have not been established. We herein generated an AQP1-GFP reporter hiPSC line and developed a combination treatment with transforming growth factor (TGF) β2 and epidermal growth factor (EGF) to induce hiPSC-derived hepatoblasts into AQP1 + cells in vitro. By confirming that the isolated AQP1 + cells showed similar gene expression patterns to cholangiocyte progenitors at the remodeling ductal plate stage around gestational week (GW) 20, we established a differentiation protocol from hiPSCs through SOX9 + CK19 + AQP1 - ductal plate-like cells into SOX9 + CK19 + AQP1 + remodeling ductal plate-like cells. We further generated 3D bile duct-like structures from the induced ductal plate-like cells. These results suggest that AQP1 is a useful marker for the generation of remodeling ductal plate cells from hiPSCs. Our methods may contribute to elucidating the differentiation mechanisms of ductal plate cells and the pathogenesis of ductal plate malformation., (Copyright © 2019 The Authors. Published by Elsevier B.V. All rights reserved.)

Aquaporin-4, present in ependymal cells, in glia limiting and abundantly in pericapillary astrocyte foot processes, and aquaporin-1, expressed in choroid plexus epithelial cells, play an important role in cerebrospinal fluid production and may be involved in the pathophysiology of age-dependent hydrocephalus. The finding that brain aquaporins expression is regulated by low oxygen tension led us to investigate how hypoxia and elevated levels of cerebral aquaporins may result in an increase in cerebrospinal fluid production that could be associated with a hydrocephalic condition. Here we have explored, in young and aged mice exposed to hypoxia, whether aquaporin-4 and aquaporin-1 participate in the development of age-related hydrocephalus. Choroid plexus, striatum, cortex and ependymal tissue were analyzed separately both for mRNA and protein levels of aquaporins. Furthermore, parameters such as total ventricular volume, intraventricular pressure, cerebrospinal fluid outflow rate, ventricular compliance and cognitive function were studied in wild type, aquaporin-1 and aquaporin-4 knock-out animals subjected to hypoxia or normoxia. Our data demonstrate that hypoxia is involved in the development of age-related hydrocephalus by a process that depends on aquaporin-4 channels as a main route for cerebrospinal fluid movement. Significant increases in aquaporin-4 expression that occur over the course of animal aging, together with a reduced cerebrospinal fluid outflow rate and ventricular compliance, contribute to produce more severe hydrocephalus related to hypoxic events in aged mice, with a notable impairment in cognitive function. These results indicate that physiological events and/or pathological conditions presenting with cerebral hypoxia/ischemia contribute to the development of chronic adult hydrocephalus., (Copyright © 2018 Elsevier B.V. All rights reserved.)

Objective: To explore the role of aquaporin 1 (AQP1) in regulation of amniotic fluid volume and composition. To investigate the effects of AQP1 gene knockout on expression of other aquaporin water channels (AQP3, AQP8 and AQP9) in placentas and fetal membranes., Methods: Mice were sacrificed at 9.5, 13.5 and 16.5 gestational day (GD). Amniotic fluid volume, osmolality and composition, fetal membranes, placental and fetal weights as well as placenta areas were recorded in Aqp1 homozygote conceptus group, heterozygote conceptus group and wild-type group, respectively. The expression of AQP1, AQP3, AQP8 and AQP9 mRNA and protein in placenta and fetal membranes were examined by quantitative Reverse Transcription-Polymerase Chain Reaction (RT-PCR) and Western blotting., Results: Aqp1 homozygote conceptus had a greater volume of amniotic fluid, lower osmolality and calcium concentration than their wild-type counterparts at 16.5 GD. There was no significant difference in expression of AQP1, AQP3, AQP8 and AQP9 in placentas among three groups. While expression of AQP8 was increased at 13.5 and 16.5 GD in fetal membranes, the expression of AQP9 was significantly decreased in fetal membranes in Aqp1 homozygote group compared with Aqp1 heterozygote and wild-type groups., Conclusion: AQP1 may play an important role in the homeostasis of maternal-fetal fluid at late gestation days. The mechanism of mutual compensation among AQPs gene needs further investigation., (Copyright © 2018 Elsevier B.V. All rights reserved.)

Background: Intramedullary ependymal cysts of the spinal cord are rare, benign, fluid-filled cysts usually situated along the ventral surface of the spinal cord. Only 32 cases have been reported since they were first described. Thus, owing to the rarity at which these cysts are encountered, their management and pathogenesis remain controversial. Whereas some investigators have advocated for cystosubarachnoid shunt placement for symptomatic ependymal cysts, others have argued for complete cyst resection or simple fenestration. Here we report the case of a 56-year-old female with a T11-T12 ependymal cyst that was successfully managed with cyst fenestration. We further investigated a potential pathological mechanism of cyst formation by performing immunohistochemistry to detect aquaporin expression in the cyst lining., Case Description: A 56-year-old female was found to harbor an enlarging cystic lesion of the conus that was discovered on workup of progressive paraparesis and urinary incontinence. She had lower extremity weakness and progressive myelopathy. Thoracic laminectomy with cyst fenestration arrested her neurologic deterioration. Pathological analysis revealed an intramedullary ependymal cyst. Immunohistochemistry was subsequently performed for expression of aquaporin-1 and aquaporin-4. There was dense staining of the underlying neuropil with concurrent membranous staining pattern of the cyst lining., Conclusions: Intramedullary ependymal cysts are rare, cystic lesions of the spinal cord. Early cyst fenestration decompresses the cyst and prevents neurologic deterioration. Here we report for the first time that aquaporins are expressed in the cyst wall, which is consistent with a passive, osmotic pathogenic mechanism of cyst formation., (Published by Elsevier Inc.)

In this study, effects of estradiol, progesterone and genistein on uterine aquaporin (AQP)-1, 2, 5 and 7 expression were investigated in sex-steroid deficient state which could help to elucidate the mechanisms underlying uterine fluid volume changes that were reported under these hormone and hormone-like compound influences., Methods: Uteri from ovariectomized, female Sprague-Dawley rats receiving seven days estradiol, progesterone or genistein (25, 50 and 100mg/kg/day) were harvested and levels of AQP-1, 2, 5 and 7 proteins and mRNAs were determined by Western blotting and Real-time PCR (qPCR) respectively. Distribution of these proteins in uterus was observed by immunohistochemistry., Results: Genistein caused a dose-dependent increase in uterine AQP-1, 2, 5 and 7 protein and mRNA expression, however at the levels lower than following estradiol or progesterone stimulations. Effects of genistein were antagonized by estradiol receptor blocker, ICI 182780. Estradiol caused the highest AQP-2 protein and mRNA expression while progesterone caused the highest AQP-1, 5 and 7 protein and mRNA expression in uterus. AQP-1, 2, 5 and 7 protein were found to be distributed in the myometrium as well as in uterine luminal and glandular epithelia and endometrial blood vessels. In conclusion, the observed effects of estradiol, progesterone and genistein on uterine AQP-1, 2, 5 and 7 expression could help to explain the differences in the amount of fluid accumulated in the uterus under these different conditions., (Copyright © 2016 Elsevier Inc. All rights reserved.)

Aims: One-lung ventilation (OLV) is a standard practice in thoracic surgery. However, OLV can give rise to arterial hypoxemia. Hypoxia-inducible transcription factor-1 alpha (HIF-1α), vascular endothelial growth factor (VEGF) and aquaporin-1 (AQP-1) may be involved in arterial hypoxemia and contribute to cellular injury. Therefore, in the present study, these moieties were investigated in an OLV rat model., Main Methods: Forty Sprague-Dawley (S-D) rats were randomly divided into four groups: right lung mechanical ventilation for 0.5 h (Group A); 1 h (Group B); 2 h (Group C) and mechanical ventilation of both lungs (control group). Rat lung tissue was examined using electron microscopy. Serum and lung tissue levels of VEGF were measured by ELISA, Western blot analyses were used to detect the protein expression of HIF-1α and immunohistochemical staining and real-time polymerase chain reaction (PCR) were performed to examine protein expression and gene levels, respectively, of VEGF and AQP-1 after hypoxia., Key Findings: Electron microscopy revealed that increased duration of OLV was correlated with greater destruction of the non-ventilated lung. The protein expression of HIF-1α was significantly increased in the non-ventilated lungs of the experimental hypoxia groups (A-C) compared to the control group, whereas VEGF and AQP-1 protein expression and gene levels were decreased in the non-ventilated lungs of the hypoxia groups (A-C) compared to the control group., Significance: The OLV caused hypoxia in the non-ventilated lung and subsequent injury. The altered expression of HIF-1α, VEGF, and AQP-1 may be involved in the pathological process of lung injury caused by hypoxia., (Copyright © 2015 Elsevier Inc. All rights reserved.)

Aquaporins (AQPs) are water channels responsible for transport of water and, in some cases, transport of small solutes such as urea and glycerol across lipid bilayer membranes. Hematophagous insects, such as Rhodnius prolixus, ingest large volumes of fluid and must rapidly eliminate the excess of water and salts from the blood meal within the gut. In order to deal with this increase in body fluid volume, a hormone-controlled diuresis is activated, during which a high rate of water and salt absorption occurs across the anterior midgut, followed by secretion of water and salts by the Malpighian tubules (MTs). Previously, one member of the MIP family (major intrinsic protein that includes the AQP family) was identified in the MTs of R. prolixus, and named RpMIP. We have described here that the RpMIP gene has different variants, and is present in tissues other than MTs. In addition, we have characterized a new AQP (RhoprAQP1) found in different tissues of R. prolixus. The expression of these transcripts in unfed insects as well as blood fed insects was evaluated using real-time quantitative PCR. Molecular models of the predicted proteins were constructed and the characteristics of their pores evaluated. A yeast complementation assay was used to validate that the products of these transcripts were bona fide AQPs. Both RhoprAQP1 and RhoprMIP-A were capable of transporting water whereas RhoprMIP-A was also capable of transporting H2O2. Taken together, these analyses suggest that RhoprMIP is probably an aquaglyceroporin, while RhoprAQP1 appears to be a strict aquaporin that transports only water., (Copyright © 2013 Elsevier Ltd. All rights reserved.)

Introduction: Aquaporin channels (AQPs) are a group of integral membrane proteins that regulate the transport of water through cell membranes. Previous studies have shown that up-regulation of AQP1 and AQP4, two of the predominant AQPs in the human brain, in high grade glial tumors contribute to cerebral edema. Others link AQPs to the regulation of human glioma cell migration and invasion. The aim of this study was to determine AQPs expression in tumor tissue harboring 5-aminolevulinic acid (ALA)-induced porphyrin fluorescence with flow cytometry and compare it to the expression in normal brain tissue., Methods: Tissue samples were obtained from fluorescing brain tumors of 26 patients treated with ALA prior to surgery (20 mg/kg b.w.). Expression levels of aquaporin channels were measured in primary tissue cultures using a FACS CANTO I flow cytometer. A control group consisted of four non-fluorescing tissue samples, the C6 and the U87 cell line., Results: Nineteen gliomas (14 high grade, 5 low grade) and 7 metastases were analyzed. On the 4th post-operative day, expression levels of AQP4 channels, but not of AQP1 channels, were significantly increased in samples from fluorescing tissue compared to non-fluorescing tissue. In addition we could see how ALA induces fluorescence in metastases., Conclusion: Flow cytometry appears to be an auspicious method for the analysis of porphyrins and AQPs in primary brain cell tumor cultures. ALA fluorescing tissue showed higher AQP4 expression compared to normal brain tissue. The demonstrated expression in a context with ALA could open a targeted therapeutic spectrum, for example to selectively target AQP4., (Copyright © 2013 Elsevier B.V. All rights reserved.)

Background: The aim of this study was to investigate the mechanism by which low-dose mifepristone serves as an antiimplantation contraceptive drug. A human endometrial explant system was used to study the effects of low-dose mifepristone (65 nmol/L and 200 nmol/L) on expression of the water channel family aquaporins, aquaporin-1 and aquaporin-2 (AQP1/AQP2), at the time of implantation., Study Design: Endometrial samples from 17 normally cycling patients at the "window of implantation" were treated with different concentrations of mifepristone. The protein and mRNA expression of AQP1/AQP2 in the endometrium was examined using immunohistochemistry (IHC) and reverse transcriptase-polymerase chain reaction (RT-PCR), respectively., Results: The IHC and RT-PCR analyses demonstrated that expression of AQP1/AQP2 was increased by mifepristone in a dose-dependent manner, with the highest AQP1/AQP2 expression levels detected in subjects treated with 200-nmol/L mifepristone., Conclusion: Low-dose mifepristone may negatively regulate implantation by increasing AQP1/AQP2 protein and mRNA expression. The findings from this study provide further evidence to support the potential contraceptive activity of low-dose mifepristone., (Copyright © 2013 Elsevier Inc. All rights reserved.)

In marine teleosts, the aqp1ab water channel plays a vital role in the development of the pelagic egg phenotype. However, the developmental control of aqp1ab activation during oogenesis remains to be established. Here, we report the isolation of the 5'-flanking region of the teleost gilthead seabream aqp1ab gene, in which we identify conserved cis-regulatory elements for the binding of the nuclear progestin receptor (Pgr) and members of the Sox family of transcription factors. Subcellular localization studies indicated that the Pgr, as well as sox3 and -8b transcripts, are co-expressed in seabream oogonia, whereas in meiosis-arrested primary growth (pre-vitellogenic) oocytes, when aqp1ab mRNA and protein are first synthesized, the Pgr appears to be completely translocated from the ooplasm into the nucleus. By contrast, sox9b is highly expressed in more advanced oocytes, coinciding with a strong depletion of aqp1ab transcripts in the oocyte. Functional characterization of wild-type and mutated aqp1ab promoter constructs, using mammalian cells and Xenopus laevis oocytes, demonstrated that aqp1ab transcription is initiated by the Pgr, which is activated by the progestin 17α,20β-dihydroxy-4-pregnen-3-one (17,20β-P), the natural ligand of the seabream Pgr. In vitro incubation of seabream primary ovarian explants with the follicle-stimulating hormone or 17,20β-P confirmed that progestin-activated Pgr enhanced Aqp1ab synthesis via the aqp1ab promoter. However, transactivation assays in heterologous systems showed that Sox transcription factors can potentially modulate this mechanism. These data uncover the existence of an endocrine pathway involved in the early activation of a water channel necessary for egg formation in marine teleosts., (Copyright © 2013 Elsevier Inc. All rights reserved.)

Erythroid ontogeny is characterized by overlapping waves of primitive and definitive erythroid lineages that share many morphologic features during terminal maturation but have marked differences in cell size and globin expression. In the present study, we compared global gene expression in primitive, fetal definitive, and adult definitive erythroid cells at morphologically equivalent stages of maturation purified from embryonic, fetal, and adult mice. Surprisingly, most transcriptional complexity in erythroid precursors is already present by the proerythroblast stage. Transcript levels are markedly modulated during terminal erythroid maturation, but housekeeping genes are not preferentially lost. Although primitive and definitive erythroid lineages share a large set of nonhousekeeping genes, annotation of lineage-restricted genes shows that alternate gene usage occurs within shared functional categories, as exemplified by the selective expression of aquaporins 3 and 8 in primitive erythroblasts and aquaporins 1 and 9 in adult definitive erythroblasts. Consistent with the known functions of Aqp3 and Aqp8 as H2O2 transporters, primitive, but not definitive, erythroblasts preferentially accumulate reactive oxygen species after exogenous H2O2 exposure. We have created a user-friendly Web site (http://www.cbil.upenn.edu/ErythronDB) to make these global expression data readily accessible and amenable to complex search strategies by the scientific community.

Laminar shear stress (LSS) due to blood flow contributes to the maintenance of endothelial health by multiple mechanisms including promotion of wound healing. The present study examined the hypothesis that the induction of water channel aquaporin 1 (AQP1) expression by LSS might be functionally associated with endothelial wound healing. When human umbilical vein endothelial cells were exposed to LSS at 12 dyn cm(-2) for 24h, significant increases in AQP1 expression were observed at the mRNA and protein levels as compared with static control. In the in vitro scratch wound healing assay, LSS treatments before and after wound creation enhanced endothelial wound healing and this effect was significantly attenuated by selective suppression of AQP1 expression using small interfering RNA. Ectopic expression of AQP1 enhanced wound healing in the absence of LSS. This study demonstrated that LSS stimulates the endothelial expression of AQP1 that plays a role in wound healing., (Copyright © 2012 Elsevier Inc. All rights reserved.)

Changes in hepatic vasculature accompany fibrogenesis, and targeting angiogenic molecules often attenuates fibrosis in animals. Aquaporin-1 (AQP1) is a water channel, overexpressed in cirrhosis, that promotes angiogenesis by enhancing endothelial invasion. The effect of AQP1 on fibrogenesis in vivo and the mechanisms driving AQP1 expression during cirrhosis remain unclear. The purpose of this study was to test the effect of AQP1 deletion in cirrhosis and explore mechanisms regulating AQP1. After bile duct ligation, wild-type mice overexpress AQP1 that colocalizes with vascular markers and sites of robust angiogenesis. AQP1 knockout mice demonstrated reduced angiogenesis compared with wild-type mice, as evidenced by immunostaining and endothelial invasion/proliferation in vitro. Fibrosis and portal hypertension were attenuated based on immunostaining, portal pressure, and spleen/body weight ratio. AQP1 protein, but not mRNA, was induced by hyperosmolality in vitro, suggesting post-transcriptional regulation. Endothelial cells from normal or cirrhotic mice were screened for microRNA (miR) expression using an array and a quantitative PCR. miR-666 and miR-708 targeted AQP1 mRNA and were decreased in cirrhosis and in cells exposed to hyperosmolality, suggesting that these miRs mediate osmolar changes via AQP1. Binding of the miRs to the untranslated region of AQP1 was assessed using luciferase assays. In conclusion, AQP1 promotes angiogenesis, fibrosis, and portal hypertension after bile duct ligation and is regulated by osmotically sensitive miRs., (Copyright © 2011 American Society for Investigative Pathology. Published by Elsevier Inc. All rights reserved.)

Excessive intraperitoneal absorption of glucose during peritoneal dialysis has both local cytotoxic and systemic metabolic effects. Here we evaluate peritoneal dialysis solutions containing L-carnitine, an osmotically active compound that induces fluid flow across the peritoneum. In rats, L-carnitine in the peritoneal cavity had a dose-dependent osmotic effect similar to glucose. Analogous ultrafiltration and small solute transport characteristics were found for dialysates containing 3.86% glucose, equimolar L-carnitine, or combinations of both osmotic agents in mice. About half of the ultrafiltration generated by L-carnitine reflected facilitated water transport by aquaporin-1 (AQP1) water channels of endothelial cells. Nocturnal exchanges with 1.5% glucose and 0.25% L-carnitine in four patients receiving continuous ambulatory peritoneal dialysis were well tolerated and associated with higher net ultrafiltration than that achieved with 2.5% glucose solutions, despite the lower osmolarity of the carnitine-containing solution. Addition of L-carnitine to endothelial cells in culture increased the expression of AQP1, significantly improved viability, and prevented glucose-induced apoptosis. In a standard toxicity test, the addition of L-carnitine to peritoneal dialysis solution improved the viability of L929 fibroblasts. Thus, our studies support the use of L-carnitine as an alternative osmotic agent in peritoneal dialysis.

Aims: The cystic fibrosis transmembrane conductance regulator (CFTR) is a cyclic AMP regulated chloride channel expressed in the apical plasma membrane of pancreatic duct cells where it plays an important role in fluid secretion. The purpose of this study was to elucidate the role of the CFTR chloride channel on ion and fluid secretion from the guinea-pig pancreas by manipulating the expression of CFTR by RNA interference or by luminal application of a CFTR selective activator, MPB91, in isolated cultured pancreatic ducts., Materials and Methods: Using cDNA isolated from the guinea-pig small intestine, fragments of the CFTR gene were generated by polymerase chain reaction and directly sequenced. Two different RNA duplexes for small interference RNA (siRNA) were designed from the sequence obtained. Fluid secretion from the isolated guinea-pig pancreatic ducts was measured using video-microscopy. The amount of CFTR chloride channel or AQP1 water channel expressed in pancreatic ducts was examined by immunoblotting with antibodies against CFTR or AQP1, respectively., Results: Guinea-pig CFTR consists of 1481 amino acid residues. An additional glutamine residue was found to be inserted between amino acid residues 403 and 404 of human CFTR. Forskolin-stimulated fluid secretion from intact pancreatic ducts was significantly higher in the presence of MPB91 compared to fluid secretion in the absence of MPB91. Both basal and forskolin-stimulated fluid secretion in pancreatic ducts transfected with CFTR specific siRNAs were reduced by ∼50% compared to fluid secretion from ducts transfected with scrambled negative control dsRNAs. The amount of CFTR and AQP1 proteins was reduced to 34% and 45% of control, respectively., Conclusions: The activity of the CFTR chloride channel or the amount of CFTR protein expressed determines the rate of fluid secretion from the isolated guinea-pig pancreatic ducts., (Copyright © 2011 Elsevier Inc. All rights reserved.)

Background: During the process of degenerative aging of the intervertebral disc (IVD), the extracellular matrix (ECM) environment changes, with osmolarity and oxygen (O(2)) concentration important components of such changes. The IVD cells respond to maintain the homeostasis and function of the IVD by several mechanisms. Aquaporin-1 (AQP-1) is a transmembrane channel protein that is permeable to water and O(2), which prevents rapid volume deformation under osmotic stress and facilitates O(2) diffusion across the plasma membrane. One hypothesis is that AQP-1 has potential roles in aging degeneration of IVDs., Methods: In this study, AQP-1 expression levels were investigated in aging rabbit nucleus pulposus (NP) cells using immunohistochemistry and Western blotting in vivo, and different osmolarities and O(2) concentrations in vitro by quantitative real-time PCR., Results: The results showed that AQP-1 was expressed at different levels in aging rabbit's NPs and AQP-1 was regulated by the NP cells in different ECM environmental conditions. AQP-1 was downregulated under hypo-osmotic stress to prevent rapid swelling deformation and was upregulated under hypoxic stress to facilitate O(2) utilization., Conclusion: It is suggested that AQP-1 may reflect the status of aged IVDs and have a potential role in reflecting the adaptability of NP cells under different adverse ECM environments in aging degenerated IVDs.

Prevention of cation permeation in wild-type aquaporin-1 (AQP1) is believed to be associated with the Asn-Pro-Ala (NPA) region and the aromatic/arginine selectivity filter (SF) domain. Previous work has suggested that the NPA region helps to impede proton permeation due to the protein backbone collective macrodipoles that create an environment favoring a directionally discontinuous channel hydrogen-bonded water chain and a large electrostatic barrier. The SF domain contributes to the proton permeation barrier by a spatial restriction mechanism and direct electrostatic interactions. To further explore these various effects, the free-energy barriers and the maximum cation conductance for the permeation of various cations through the AQP1-R195V and AQP1-R195S mutants are predicted computationally. The cations studied included the hydrated excess proton that utilizes the Grotthuss shuttling mechanism, a model "classical" charge localized hydronium cation that exhibits no Grotthuss shuttling, and a sodium cation. The hydrated excess proton was simulated using a specialized multi-state molecular dynamics method including a proper physical treatment of the proton shuttling and charge defect delocalization. Both AQP1 mutants exhibit a surprising cooperative effect leading to a reduction in the free-energy barrier for proton permeation around the NPA region due to altered water configurations in the SF region, with AQP1-R195S having a higher conductance than AQP1-R195V. The theoretical predictions are experimentally confirmed in wild-type AQP1 and the mutants expressed in Xenopus oocytes. The combined results suggest that the SF domain is a specialized structure that has evolved to impede proton permeation in aquaporins., (Copyright © 2011 Elsevier Ltd. All rights reserved.)

The aim of this study was to investigate the protective effect of inhibition of aquaporin-1 (AQP1) expression against aristolochic acid I (AA-I)-induced apoptosis. HK-2 cells impaired by AA-I were used in this study as the cell model of aristolochic acid nephropathy. Apoptosis was studied by different methods, including 3-(4,5-dimethyl-thiazol-2-yl)-2,5-diphenyl-tetrazolium bromide (MTT) assays, flow cytometry, and caspase 3 activity assays. We compared AA-I-mediated apoptosis in HK-2 cells with or without knockdown of AQP1 expression by RNA interference. MTT assays showed that AA-I inhibited the viability of HK-2 cells in a time- and concentration-dependent manner. Apoptosis was evidenced by the results of the Annexin V/propidium iodide assay and the occurrence of a sub-G1 peak in cell-cycle analysis. The activity of caspase 3 was found to have been increased by AA-I in a concentration-dependent manner. However, AQP1 RNA interference provided protection against injury in cells treated with AA-I (40 μM) for 24 h and attenuated the number of apoptotic cells. These results suggested that AQP1 plays an important role in AA-I-induced apoptosis and that inhibition of AQP1 expression may protect HK-2 cells from AA-I-induced apoptotic damage., (Copyright © 2011. Published by Elsevier Inc.)

The mRNA and protein levels of aquaporin (AQP)5 in the parotid gland were found to be potentially decreased by lipopolysaccharide (LPS) in vivo in C3H/HeN mice, but only weakly in C3H/HeJ, a TLR4 mutant mouse strain. In the LPS-injected mice, pilocarpine-stimulated saliva production was reduced by more than 50%. In a tissue culture system, the LPS-induced decrease in the AQP5 mRNA level was blocked completely by pyrrolidine dithiocarbamate, MG132, tyrphostin AG126, SP600125, and partially by SB203580, which are inhibitors for IkappaB kinase, 26S proteasome, ERK1/2, JNK, and p38 MAPK, respectively. In contrast, the expression of AQP1 mRNA was down-regulated by LPS and such down-regulation was blocked only by SP600125. The transcription factors NF-kappaB (p65 subunit), p-c-Jun, and c-Fos were increased by LPS given in vivo, whereas the protein-binding activities of the parotid gland extract toward the sequences for NF-kappaB but not AP-1-responsive elements present at the promoter region of the AQP5 gene were increased by LPS injection. Co-immunoprecipitation by using antibody columns suggested the physical association of the three transcription factors. These results suggest that LPS-induced potential down-regulation of expression of AQP5 mRNA in the parotid gland is mediated via a complex(es) of these two classes of transcription factors, NF-kappaB and p-c-Jun/c-Fos.

The outcome of long-term exposure to dietary isoflavones on estrogen sensitive tissues is discussed controversially. We performed a study on tissue specific effects of lifelong isoflavone exposure on the rat uterus with exposure being initiated prenatally. We compare the effects of the dietary isoflavones, genistein (GEN) and daidzein, or GEN alone to those of isoflavone free diet. Therefore, one group received a phytoestrogen-free diet (PE-free), one an isoflavone-high diet (ISO-high) and one the PE-free diet supplemented with GEN (GEN-rich) throughout their whole lifetime. In ovariectomized adult females a uterotrophic assay was performed, comparing 17beta-estradiol, GEN and two estrogen receptor subtype-specific agonists. The uterus wet weight, the uterine epithelial heights, and uterine markers for proliferation, estrogenicity and estrogen-dependent water channels were determined on mRNA and protein level. The dietary ISO pre-exposure results in a much stronger uterine weight increase following external ERalpha-mediated estrogenic stimuli than seen in the PE-free group. These strongly increased effects were not exclusively due to proliferation hence proliferation associated parameters were almost identical in all groups. Additionally, gene expression analysis showed that estrogen-dependent water channels are highly affected by ISO-containing diets. In conclusion, the lifelong dietary ISO ingestion enhances severely the uterine responsiveness to ERalpha-mediated estrogenic stimuli in female rats. While the uterine proliferation rate was not affected, the water homeostasis was highly affected. Our data clearly demonstrate that estrogen responsiveness is highly modulated by dietary isoflavones. Whether this estrogen sensitivity shift is beneficial or adverse to health remains to be elucidated. However, this is highly relevant for interpreting data from regional differences in endocrine cancer., (Copyright 2010 Elsevier Ireland Ltd. All rights reserved.)

A significant long-term side effect of radiation therapy for head and neck cancers is xerostomia, a dry mouth, due to salivary gland damage. Despite continuing efforts to eliminate this problem, many patients continue to suffer. This brief review describes our efforts to develop a gene transfer approach, employing the aquaporin-1 cDNA, to treat patients with existing radiation-induced salivary hypofunction. A Phase I/II clinical trial, using a recombinant adenoviral vector to mediate gene transfer, is currently underway.

We examined the expression of aquaporin (AQP)-1 in monolayers of the rat gastric epithelial cell line RGM1 and investigated the roles AQP1 plays in the epithelial restitution during wound healing. A round wound of constant size was produced in the center of a confluent cell monolayer using a rotating silicon tip. The RGM1 cells expressed AQP1 mRNA. Hg(2+) (HgCl(2)), an inhibitor of AQPs, suppressed cell migration during wound repair in a concentration-dependent manner. Likewise, cell migration was also impaired in cells in which AQP1 was knocked down by RNA interference, resulting in a marked delay of wound healing. The AQP1 knockdown RGM1 cells showed a decrease in the formation of membrane protrusions (lamellipodia) at the leading edge of the wound as compared with control RGM1 cells. These results suggest for the first time that AQP1 plays a crucial role in gastric epithelial cell migration during wound healing.

Objective: To explore the pathophysiology of oligohydramnios, the association between the expression of aquaporin 1 and aquaporin 3 in fetal membranes and placenta and oligohydramnios was investigated., Methods: Sixty patients underwent elective cesarean sections at term were studied, 30 patients with isolated oligohydramnios and the other 30 with normal amniotic fluid volume (AFV). Real-time polymerase chain reaction and immunohistochemistry were employed to determine expression and localization of aquaporin 1 and aquaporin 3 in amnion, chorion and placenta, respectively., Results: The expression of aquaporin 1 and aquaporin 3 was detected in amnion, chorion and placenta using real-time RT-PCR. By immunohistochemistry, aquaporin 1 and aquaporin 3 protein expressions in amnion epithelia and chorion cytotrophoblasts were identified. In placenta, aquaporin 1 was detected in placental vessels, while aquaporin 3 was found in trophoblast cells. In comparison to normal AFV group, there was a significant decrease of aquaporin 1 expression in amnion in oligohydramnios group, but no significant difference in chorion and placenta between the two groups. The expression of the aquaporin 3 in amnion and chorion in oligohydramnios group was significantly decreased, while expression in placenta was significantly increased compared with that in normal AFV group., Conclusions: Alteration of aquaporin 1 and aquaporin 3 expression in fetal membranes and placenta may be important in the pathophysiology of isolated oligohydramnios.

The permeability of water and cryoprotectants through the plasma membrane is very important for cryopreservation of mammalian cells. Aquaporin 1 (AQP1) is one of the water channel proteins localized on the membranes of various cells including reproductive organs, allowing water to flow rapidly across the plasma membranes in the direction of osmotic gradients. Although mRNA expression of AQP1 was reported in the mammalian testis by reverse transcription polymerase chain reaction (RT-PCR), protein and mRNA expressions of AQP1 have not been confirmed to date in the sperm of any species. The present study was conducted to determine whether AQP1 mRNA is expressed and AQP1 protein exists in canine spermatozoa. Results from RT-PCR showed that AQP1 mRNA was expressed in canine spermatozoa as well as the testis. The size was similar to the one from canine genomic DNA as a positive control. In sperm, AQP1 protein was also detected by canine AQP1 specific antibody. From these results, both AQP1 mRNA and protein are expressed in male gamete in the dog. Expression of AQP1 may be involved in the flux of water during the cryopreservation of spermatozoa.

Polycystic kidney (PCK) rats are a spontaneous model of autosomal recessive polycystic kidney disease that exhibit cholangiocyte-derived liver cysts. We have previously reported that in normal cholangiocytes a subset of vesicles contain three proteins (ie, the water channel AQP1, the chloride channel CFTR, and the anion exchanger AE2) that account for ion-driven water transport. Thus, we hypothesized that altered expression and location of these functionally related proteins contribute to hepatic cystogenesis. We show here that under basal conditions and in response to secretin and hypotonicity, cysts from PCK rats expanded to a greater degree than cysts formed by normal bile ducts. Quantitative reverse transcriptase-polymerase chain reaction, immunoblot analysis, and confocal and immunoelectron microscopy all indicated increased expression of these three proteins in PCK cholangiocytes versus normal cholangiocytes. AQP1, CFTR, and AE2 were localized preferentially to the apical membrane in normal rats while overexpressed at the basolateral membrane in PCK rats. Exposure of the cholangiocyte basolateral membrane to CFTR inhibitors [5-nitro-2-(3-phenylpropylamino)-benzoic acid and CFTRinh172], or Cl(-)/HCO(3)(-) exchange inhibitors (4,4'-diisothiocyanatostilbene-2,2'-disulfonic acid disodium salt hydrate and 4-acetamido-4'-isothiocyanato-2,2'-stilbenedisulfonic acid disodium salt hydrate) blocked secretin-stimulated fluid accumulation in PCK but not in normal cysts. Our data suggest that hepatic cystogenesis in autosomal recessive polycystic kidney disease may involve increased fluid accumulation because of overexpression and abnormal location of AQP1, CFTR, and AE2 in cystic cholangiocytes. Therapeutic interventions that block the activation of these proteins might inhibit cyst expansion in polycystic liver disease.

Aquaporins (AQPs) are water channels that regulate water flow in many tissues. As AQP1 is a candidate to regulate placental fluid exchange, we sought to investigate the effect of arginine vasopressin (AVP) and cAMP agonists on AQP1 gene expression in first trimester-derived extravillous cytotrophoblasts (HTR-8/Svneo) and two highly proliferative carcinoma trophoblast-like cell lines but with a number of functional features of the syncytiotrophoblast namely; JAR and JEG-3 cells. Our data demonstrated that AVP (0.1 nM) significantly increased the expression of AQP1 mRNA at 10 h in HTR-8/SVneo and JEG-3 cells (P<0.05). Both SP-cAMP, a membrane-permeable and phosphodiesterase resistant cAMP, and forskolin, an adenylate cyclase stimulator significantly increased AQP1 mRNA expression in all cell lines after 2 h in a dose-dependent manner (P<0.05) with a parallel increase in protein expression. In the time course study, 5 microM of either SP-cAMP or forskolin significantly stimulated AQP1 mRNA expression after 2 h in HTR-8/SVneo cells and after 10 h in JAR and JEG-3 cells. AQP1 protein expression was highest after 20 h in both HTR-8/SVneo and JEG-3 cells (P<0.05). AVP-stimulated cAMP elevation was blocked in the presence of 9-(tetrahydro-2'-furyl) adenine (SQ22536) (100 microM), a cell-permeable adenylate cyclase inhibitor (P<0.05). These results indicate that in trophoblasts-like cells AQP1 gene expression is upregulated by both AVP and cAMP agonists. Furthermore, our data demonstrate that a cAMP-dependent pathway is responsible for the AVP effect on AQP1. Thus, modulation of AQP1 expression by maternal hormones may regulate invasion and fetal-placental-amnion water homeostasis during gestation.

Glioblastoma multiformes (GBMs) express increased aquaporin (AQP) 1 compared to normal brain. AQPs may contribute to edema, cell motility, and shuttling of H(2)O and H(+) from intracellular to extracellular space. We sought to gain insight into AQP1 function in GBM. In cultured 9L gliosarcoma cells, AQP1 expression was induced by dexamethasone, platelet-derived growth factor, NaCl, hypoxia, D-glucose (but not L-glucose), and fructose. Induction of AQP1 expression correlated with the level of glycolysis, maximized by increasing medium D-glucose or fructose and decreasing O(2), and was quantified by measuring lactate dehydrogenase (LDH) activity and medium lactate concentration. Upregulation of the protease cathepsin B was also observed in 9L cells cultured under glycolytic conditions. Immunohistochemical staining of human GBM specimens revealed increased coincident expression of AQP1, LDH, and cathepsin B in glioma cells associated with blood vessels at the tumor periphery. GBMs are known to exhibit aerobic glycolysis. Increased glucose metabolism at the tumor periphery may provide a scenario by which upregulation of AQP1, LDH, and cathepsin B contributes to acidification of the extracellular milieu and to invasive potential of glioma cells in perivascular space. The specific upregulation and metabolic consequences of increased AQP1 in gliomas may provide a therapeutic target, both as a cell surface marker and as a functional intervention.

Objectives: To assess the role of aquaporins (AQPs) in the regulation of amniotic fluid (AF) volume, we determined AF volume and composition and placental and fetal membrane AQP expression throughout the second half of murine gestation., Methods: Pregnant CD1 mice were sacrificed at e10-19 and AF volume and composition determined. Placenta and fetal membranes were screened for AQP gene expression. AQP gene expression was quantified by real-time RT PCR and protein location determined by immunohistochemistry. Changes in AF volume were correlated with AQP expression., Results: Both membranes and placenta demonstrated expression of AQP1, -3, -8 and -9. Advancing gestation was associated with increased AF volume from e10 to e16, with a marked decrease in AF volume from e16 to e19. By immunohistochemistry, AQP1 was localized to placental vessels and AQP3 to trophoblast. AF volume was negatively correlated with fetal membrane AQP1 and placental AQP1 and AQP9 expression, and positively correlated with placental AQP3 expression., Conclusion: Changes in AQPs with advancing gestation, and their correlation with AF volume, suggest a role in mediating placental and membrane water flow and ultimately AF volume. AQP1 appears to regulate fetal membrane water flow, and AQP3 is a likely candidate for the regulation of placental water flow.

The water channel aquaporin-1 (AQP1) is considered as the molecular counterpart of the ultrasmall pore predicted by the three-pore model of fluid transport across the peritoneal membrane. However, the definitive proof of the implication of AQP1 in solute-free water transport, sodium sieving, and ultrafiltration (UF) during peritoneal dialysis (PD) is lacking, and the effects of its deletion on the structure of the membrane are unknown. Using real-time reverse transcriptase-polymerase chain reaction and immunogold electron microscopy, we showed that AQP1 is the most abundant member of the AQP gene family expressed in the mouse peritoneum, and the only one located in the capillary endothelium. Transport studies during a 2-h dwell demonstrated that, in comparison with Aqp1(+/+) littermates, Aqp1(-/-) mice had no sodium sieving; an approximately 70% decrease in the initial, solute-free UF; and an approximately 50% decrease in cumulative UF. These modifications occurred despite unchanged osmotic gradient and transport of small solutes in the Aqp1(-/-) mice. Heterozygous Aqp1(+/-) mice showed intermediate values in sodium sieving and initial UF, whereas cumulative UF was similar to Aqp1(+/+) mice. The deletion of AQP1 had no effect on the expression of other AQPs and on the density, structure, or diameter of peritoneal capillaries. These data provide direct evidence for the role of AQP1 during PD. They validate essential predictions of the three-pore model: (i) the ultrasmall pores account for the sodium sieving, and (ii) they mediate 50% of UF during a hypertonic dwell.

The article by Ni et al. solidifies the important role of aquaporin-1 in the process of fluid removal from anephric patients treated with peritoneal dialysis. The presence of the water-only channel in the subperitoneal endothelia provides the mechanism for solute-free ultrafiltrate observed early in dialysis and accounts for approximately half of all the filtration observed in dialysis.

Objective: Polyhydramnios is a condition associated with significant perinatal morbidity. While the exact pathophysiology of this condition is unknown in the absence of obvious anatomic or organic etiologies, impaired intramembranous water transport has been shown. Previous studies from our laboratory have shown that the water channel aquaporin 1 (AQP1) is expressed in human fetal membranes from term pregnancies with normal amniotic fluid (AF) volume. Therefore, we hypothesized that in pregnancies with idiopathic polyhydramnios, AQP1 expression might be reduced in fetal membranes from pregnancies with this AF volume disorder., Study Design: Placentas were collected from women at term (37-40 weeks) who presented with either polyhydramnios (amniotic fluid index [AFI] >24.0 cm) or normal AF volume (AFI 5.0-23.9 cm). Immediately after delivery, the membranes (amnion and chorion) directly overlying the placenta and the free-floating reflected membranes were sampled (total of 4 samples from each placenta). RNA was isolated from each sample and expression was quantified using real-time reverse transcriptase polymerase chain reaction (PCR) and relative quantification of gene expression., Results: Relative to pregnancies with normal AF volume, there was an increase in expression of the water channel AQP1 in all regions of the fetal membranes. The greatest increase (33-fold) was seen in the reflected amnion., Conclusion: AQP1 expression is increased in polyhydramnios. This finding suggests that alterations in AQP1 expression may be a compensatory response to and not a cause of idiopathic polyhydramnios. We speculate that therapies focused on regulating AQP1 expression may be useful for treating this condition.

C57L mice are susceptible and AKR mice are resistant to gallstone formation. We studied in male mice of both strains gallbladder histopathology, cholecystokinin-induced emptying, and concentrating function at 0, 14, 28, and 56 days on a lithogenic diet. Gallbladder wall thickness increased on the diet, with stromal granulocyte infiltration, progressive fibrosis, edema, and epithelial cell indentation, particularly in C57L. Strong basal cholecystokinin octapeptide-induced gallbladder emptying (70% of fasting volumes) occurred in both strains, but fasting gallbladder volumes were significantly larger in C57L (14.8 +/- 2.2 microl vs. 8.8 +/- 1.0 microl). On the diet, fasting volumes increased exclusively in C57L (28.6 +/- 2.9 microl on day 56), with progressively decreased emptying (27% of fasting volumes on day 56). Gallbladder emptying remained normal in AKR. Gallbladder concentrating function decreased on the lithogenic diet (especially in C57L), coinciding with decreased aquaporin-1 (AQP1) and AQP8 expression at the mRNA and protein levels. In additional experiments, similar downregulation of AQP1 and AQP8 mRNA expression occurred in farnesoid X receptor (FXR)-deficient mice after 1 week on the lithogenic diet, without any difference from corresponding wild-type mice. In conclusion, during murine lithogenesis, altered gallbladder histology is associated with impaired motility, reduced concentrating function, and decreased AQP1 and AQP8 expression, the latter without the involvement of the FXR.