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Background: Aquaporin-1 (AQP1) protein plays a crucial role in intracellular and extracellular water homeostasis and fluid transport in organs and tissues associated with diverse life activities and is extremely abundant in the kidney. Accurate detection of AQP1 in urine can be applied as screening of early-stage disease. Application of magnetic preconcentration and probe-based signal amplification strategy coupling to inductively coupled plasma mass spectrometry (ICP-MS) is a more accurate, sensitive and specific detection method for AQP1 in complex biological samples compared to conventional methods., Results: We described an element-labelling strategy based on magnetic preconcentration and probe-based immunoassay coupling to ICP-MS detection. The magnetic beads (MBs) modified with epoxy groups were capable of enriching AQP1 proteins and separating them from complex matrices. The probe constructed by conjugating anti-AQP1 antibody molecules on the surface of gold nanoparticles could specifically recognize AQP1 proteins attached on MBs and be analyzed by ICP-MS. The concentration of AQP1 protein could be precisely quantified and amplified by 14,000 times through the corresponding signal of Au atoms. This assay for AQP1 protein quantification achieved a detection limit down to 0.023 ng mL -1 , a broad linear calibration curve between 0.3 ng mL -1 and 30 ng mL -1 , as well as outstanding specificity., Significance: The proposed method was successfully applied to detect AQP1 protein in human urine samples, showing the potential for its applications concerning accurate AQP1 quantification. It can also screen a wide range of proteins provided the antibodies specific to these target proteins are available., 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 Elsevier B.V. All rights reserved.)

Systemic inflammation is a serious condition that can affect various tissues and organs, such as the kidneys, and can be life-threatening. Selenium (Se) is an antioxidant and anti-inflammatory trace element. In this study, we aimed to examine the effects of Se, which has antioxidant and anti-inflammatory properties, on lipopolysaccharide (LPS)-induced kidney damage to maintain aquaporin-1 (AQP-1) levels. Four experimental rat groups (n = 8) consisting of the control, LPS alone, LPS + Se, and Se alone were so applied for 7 consecutive days. Upon sacrifice, histopathological results, diagnostic markers of kidney functions, oxidative stress, and inflammation were analyzed. Our results showed that LPS induced mononuclear cell infiltration, cellular residue, and protein deposition in the kidney proximal tubules, and also decreased total antioxidant status levels and increased total antioxidant status and oxidative stress index values. LPS increased the level of creatinine, increased the level of Nuclear Factor kappa B, which has an important role in the inflammation process, and decreased the levels of AQP-1 due to the damage it caused. Se has shown its effect by reversing all these situations. This data suggests that Se can be used as an additive to mitigate LPS-induced toxicity in the kidney., (© 2023. The Author(s), under exclusive licence to Springer Science+Business Media, LLC, part of Springer Nature.)

Background and Purpose: Decreased aortic compliance is a precursor to numerous cardiovascular diseases. Compliance is regulated by the rigidity of the aortic wall and the vascular smooth muscle cells (VSMCs). Extracellular matrix stiffening, observed during ageing, reduces compliance. In response to increased rigidity, VSMCs generate enhanced contractile forces that result in VSMC stiffening and a further reduction in compliance. Mechanisms driving VSMC response to matrix rigidity remain poorly defined., Experimental Approach: Human aortic-VSMCs were seeded onto polyacrylamide hydrogels whose rigidity mimicked either healthy (12 kPa) or aged/diseased (72 kPa) aortae. VSMCs were treated with pharmacological agents prior to agonist stimulation to identify regulators of VSMC volume regulation., Key Results: On pliable matrices, VSMCs contracted and decreased in cell area. Meanwhile, on rigid matrices VSMCs displayed a hypertrophic-like response, increasing in area and volume. Piezo1 activation stimulated increased VSMC volume by promoting calcium ion influx and subsequent activation of PKC and aquaporin-1. Pharmacological blockade of this pathway prevented the enhanced VSMC volume response on rigid matrices whilst maintaining contractility on pliable matrices. Importantly, both piezo1 and aquaporin-1 gene expression were up-regulated during VSMC phenotypic modulation in atherosclerosis and after carotid ligation., Conclusions and Implications: In response to extracellular matrix rigidity, VSMC volume is increased by a piezo1/PKC/aquaporin-1 mediated pathway. Pharmacological targeting of this pathway specifically blocks the matrix rigidity enhanced VSMC volume response, leaving VSMC contractility on healthy mimicking matrices intact. Importantly, upregulation of both piezo1 and aquaporin-1 gene expression is observed in disease relevant VSMC phenotypes., (© 2023 The Authors. British Journal of Pharmacology published by John Wiley & Sons Ltd on behalf of British Pharmacological Society.)

Leptin is an obesity-related hormone that plays an important role in breast cancer progression. Vasculogenic mimicry (VM) refers to the formation of vascular channels lined by tumor cells. This study aimed to investigate the relationship between leptin and VM in human breast cancer cells. VM was measured by a 3D culture assay. Signal transducers and activators of transcription 3 (STAT3) signaling, aquaporin-1 (AQP1), and the expression of VM-related proteins, including vascular endothelial cadherin (VE-cadherin), twist, matrix metalloproteinase-2 (MMP-2), and laminin subunit 5 gamma-2 (LAMC2), were examined by Western blot. AQP1 mRNA was analyzed by a reverse transcriptase-polymerase chain reaction (RT-PCR). Leptin increased VM and upregulated phospho-STAT3, VE-cadherin, twist, MMP-2, and LAMC2. These effects were inhibited by the leptin receptor-blocking peptide, Ob-R BP, and the STAT3 inhibitor, AG490. A positive correlation between leptin and AQP1 mRNA was observed and was confirmed by RT-PCR. Leptin upregulated AQP1 expression, which was blocked by Ob-R BP and AG490. AQP1 overexpression increased VM and the expression of VM-related proteins. AQP1 silencing inhibited leptin-induced VM and the expression of VM-related proteins. Thus, these results showed that leptin facilitates VM in breast cancer cells via the Ob-R/STAT3 pathway and that AQP1 is a key mediator in leptin-induced VM., Competing Interests: The authors declare no conflicts of interest.

Aquaporin-1 (Aqp1), a water channel, has garnered significant interest for cell-based medicine and in vivo synthetic biology due to its ability to be genetically encoded to produce magnetic resonance signals by increasing the rate of water diffusion in cells. However, concerns regarding the effects of Aqp1 overexpression and increased membrane diffusivity on cell physiology have limited its widespread use as a deep-tissue reporter. In this study, we present evidence that Aqp1 generates strong diffusion-based magnetic resonance signals without adversely affecting cell viability or morphology in diverse cell lines derived from mice and humans. Our findings indicate that Aqp1 overexpression does not induce ER stress, which is frequently associated with heterologous expression of membrane proteins. Furthermore, we observed that Aqp1 expression had no detrimental effects on native biological activities, such as phagocytosis, immune response, insulin secretion, and tumor cell migration in the analyzed cell lines. These findings should serve to alleviate any lingering safety concerns regarding the utilization of Aqp1 as a genetic reporter and should foster its broader application as a noninvasive reporter for in vivo studies., (© 2024. The Author(s).)

Alpinetin has been reported to play a protective role in lung diseases, while its special mechanisms remain indistinct. In this study, acute lung injury (ALI) model was constructed by inducing MLE-12 cells with lipopolysaccharide (LPS). Cell activity together with apoptosis was judged employing cell counting kit-8 (CCK-8), flow cytometry along with western blot. Oxidative stress levels were measured by dichloro-dihydro-fluorescein diacetate (DCFH-DA) staining and corresponding kits. In addition, enzyme-linked immunosorbent assay (ELISA) was to examine the levels of inflammatory factors. The protein expressions of aquaporin-1 (AQP1), p38 and extracellular signal-regulated kinase (ERK) 1/2 pathway were estimated utilizing western blot. The data showed that alpinetin increased the viability, reduced the apoptosis, oxidative stress and inflammation and inactivated p38 and ERK1/2 signaling in LPS-induced MLE-12 cells. Moreover, alpinetin also increased AQP1 expression and AQP1 knockdown reversed the impacts of alpinetin on LPS-induced MLE-12 cells. Additionally, AQP1 agonist AqF026 also exerted anti-apoptotic and anti-inflammatory activities in LPS-treated MLE-12 cells. Evidently, alpinetin may exert its protective role in LPS-induced ALI by inactivation of p38 and ERK1/2 signaling through regulating AQP1., (Copyright © 2024 Elsevier Ltd. All rights reserved.)

In this study, the effects of vitamin D 3 (Vit. D) and a stinging nettle [ Urtica dioica  L. (UD)] extract were examined using histopathological and immunohistochemical methods in the stomach tissues of an experimentally created rat model of Crohn's disease (CD). The CD model was created using trinitrobenzene sulfonic acid (TNBS). The animals in the study were divided into control, TNBS, TNBS+Vit. D, and TNBS+UD groups. At the end of the experiment, the animals were euthanised and their stomach tissues were evaluated for necrosis, degeneration, apoptosis, and inflammation. Additionally, an immunohistochemical method was applied to determine the somatostatin (SSTR), aquaporin-1 (AQP-1), caspase-3, and tumour necrosis factor-alpha (TNF-α) immunoreactivity in the gastric tissues. In the evaluations, degenerative and necrotic changes and mononuclear cell infiltration areas were observed in the TNBS group, but such changes could be improved with Vit. D and UD applications. The results suggest that the combination of the Vit. D and UD extract may have a protective and therapeutic role in mitigating TNBS-induced damage to the gastric tissues, potentially through the regulation of SSTR, AQP-1, caspase-3, and TNF-α expression. This indicates a promising avenue for further research and the exploration of these compounds in the context of gastrointestinal health., Competing Interests: The authors declare no conflict of interest., (Copyright: © 2024 Gezer et al.)

Background: Nephroblastoma, also known as Wilms' tumor (WT), is an embryonic malignant tumor and one of the most common malignant tumors in the abdominal region of children. The exact role and underlying mechanisms of aquaporin-1 (AQP1) in the occurrence and development of nephroblastoma remain unclear., Methods: After overexpression of AQP1, cell proliferation was assessed using the CCK-8 proliferation assay and EdU staining. Flow cytometry was employed to assess cell apoptosis, and Western blotting (WB) analysis was conducted to validate the expression of relevant protein markers. mRNA sequencing (mRNA-Seq) was performed on WT cells overexpressing AQP1 to predict and characterize the associated mechanisms. Transmission electron microscopy was utilized to observe changes in the ultrastructure of WT cells undergoing apoptosis and pyroptosis following AQP1 overexpression. Functional in vivo validation was conducted through animal experiments., Results: We validated that overexpression of AQP1 inhibited cell proliferation and promoted cell apoptosis and pyroptosis both in vitro and in vivo. mRNA-Seq analysis of WT cells with AQP1 overexpression suggested that these effects might be mediated through the inhibition of the JAK-STAT signaling pathway. Additionally, we discovered that overexpression of AQP1 activated the classical pyroptosis signaling pathway dependent on caspase-1, thereby promoting pyroptosis in WT., Conclusion: These findings highlight the important functional role of AQP1 in the pathobiology of nephroblastoma, providing novel insights into the development of this disease. Moreover, these results offer new perspectives on the potential therapeutic targeting of AQP1 as a treatment strategy for nephroblastoma., (© 2024. The Author(s).)

Aquaporins (AQPs) are water channel proteins, and the expression of AQPs in carcinoma cells has received much attention over the last 15 years. In the veterinary field, however, little is known about the expression of AQPs. In the present study using immunohistochemistry, we examined the expression of AQP1, AQP3, and AQP5 in canine mammary gland carcinomas. The 27 samples comprised 10 grade I, 12 grade II, and 5 grade III samples (See Materials and Methods section for grade classification method). AQP1 was expressed in only 2 of the grade III carcinomas, and the expression was limited to spindle-shaped cells in the solid structure and on the outside of the solid mass. AQP3-positive cells were observed in 20 of 22 grade I and II samples. On the other hand, among grade III carcinomas, AQP3 was expressed only in spindle-shaped cells in 1 sample. AQP5 was expressed in all grade I and II carcinomas but not in the grade III tumors. In addition, enhanced expression of basolateral AQP3 and apical AQP5 was observed in lobular hyperplastic cells. These results suggest that the expression patterns of AQP3 and AQP5 can be of help for judging the grading of canine mammary tumors and that AQP1 is likely to be involved in metastasis. Moreover, AQP3 and AQP5 might be relevant to lactation in female dogs.

The choroid plexus (CP) is a structure in the brain ventricles that produces the main part of the cerebrospinal fluid (CSF). It is covered with specialized cells which show epithelial characteristics and are the site of the blood-CSF barrier. These cells form a contiguous cell sheet with ventricle-lining ependymal cells which are known to express aquaporin-4 (AQP4). In contrast, CP epithelial cells express aquaporin-1 (AQP1) apically. We investigated the expression patterns of aquaporins in the CP-ependyma transition from human body donors using immunofluorescence and electron microscopy. Ependymal cells and subependymal astrocytes at the base of the CP showed a particularly high AQP4 immunoreactivity. Astrocytic processes formed a dense meshwork or glial plate around the blood vessels entering the CP. Interestingly, some of these astrocytic processes were in direct contact with the CP stroma, which contains fenestrated blood vessels, separated only by a basal lamina. Electron microscopy confirmed the continuity of the subastrocytic basal lamina with the CP epithelium. We also probed for components of the AQP4 anchoring dystrophin-dystroglycan complex. Immunolabeling for dystrophin and AQP4 showed an overlapping staining pattern in the glial plate but not in previously reported AQP4-positive CP epithelial cells. In contrast, dystroglycan expression was associated with laminin staining in the glial plate and the CP epithelium. This suggests different mechanisms for AQP4 anchoring in the cell membrane. The high AQP4 density in the connecting glial plate might facilitate the transport of water in and out of the CP stroma and could possibly serve as a drainage and clearing pathway for metabolites.

Background: Cerebral malaria (CM) is associated with sequestration of parasitized red blood cells (PRBCs) in the capillaries. Often, the association of CM with cerebral oedema is related with high mortality rate. Morphological changes of the choroid plexus (CP) and caspase-3 expression in CM have not been reported. In addition, limited knowledge is known regarding the role of aquaporin (AQP)-1 in CM. The present study evaluated changes in the CP, explored apoptotic changes and AQP-1 expression in CP epithelial cells (CPECs) in fatal CM patients., Methods: CP from fatal Plasmodium falciparum malaria patients (5 non-CM [NCM], 16 CM) were retrieved and prepared for histopathological evaluation. Caspase-3 and AQP-1 expressions in CPECs were investigated by immunohistochemistry., Results: Histologically, apoptotic changes in CPECs were significantly observed in the CM group compared with the NCM and normal control (NC) groups (p < 0.05). These changes included cytoplasmic and nuclear condensation/shrinkage of CPECs and detachment of CPECs from the basement membrane. The apoptotic changes were positively correlated with caspase-3 expression in the nuclei of CPECs. In addition, AQP-1 expression in CPECs was significantly decreased in the CM group compared with the NCM and NC groups (all p < 0.001). A negative correlation (r s  =  - 0.450, p = 0.024) was documented between caspase-3 expression in the nuclei of CPECs and AQP-1., Conclusions: Apoptotic changes and altered AQP-1 expression may contribute to CPEC dysfunction and subsequently reduce cerebrospinal fluid production, affecting the water homeostasis in the brains of patients with CM., (© 2022. The Author(s).)

In this study, the neuroprotective effects of melatonin (MEL) with changes in apoptosis, inflammation, and histopathological morphology were evaluated in the medulla oblongata of cisplatin (CIS) administered rats. Although the side effects of CIS are known in many tissues, its reaction on the medulla oblongata and the molecular association underlying this effect is unclear. Male wistar albino rats were separated into four groups (control, CIS, CIS+MEL, and MEL) (n = 24). CIS and CIS+MEL groups were given 4 mg/kg CIS at 4-day intervals (days 1, 5, 9, and 13) by the first day of the study. The MEL and CIS+MEL groups were given 10 mg/kg MEL daily for 13 days. At the end of the study, the medulla oblongata sections of the rats were harvested on the 14th day, and the changes in gene expressions were examined. Expression levels of inflammation markers ( TNF-α and IL-6 ), apoptotic markers ( Bax and Casp-3 ), and Aqp-1 and Aqp-4 were found to significantly increase with CIS administration. On microscopic examination, hemorrhage, edema, and perivascular edema were detected in the CIS applied group compared with controls. MEL treatment significantly reduced perivascular edema (p = 0.0152) and hemorrhage (p = 0.0087). Besides, there was a significant difference between the control and CIS groups regarding pyknosis and a significant increase in pyknotic neurons in the CIS treatment group (p < 0.001). This study indicates that CIS treatment significantly impaired medulla oblongata, and combined treatment with MEL ameliorates the injury in rats., (© TÜBİTAK.)

The canonical function of aquaporin (AQP) water channels is to facilitate passive transport of water across cellular membranes making them essential in the regulation of body water homeostasis. Moreover, AQPs, including AQP1, have been found to be overexpressed in multiple cancer types, including breast cancer, where AQP1 overexpression is associated with poor prognosis. AQPs have been shown to affect cellular processes associated with cancer progression and spread including cell migration, angiogenesis, and proliferation. Moreover, AQPs can regulate levels of adhesion proteins at cell-cell junctions, a regulatory role, which is still largely unexplored in cancer. Understanding the molecular mechanisms of how AQP1 contributes to breast cancer progression and metastatic processes is essential to establish AQP1 as a biomarker and to develop targeted anticancer treatments for breast cancer patients. This mini-review focuses on the role of AQP1 in breast cancer., (© 2021 Scandinavian Societies for Medical Microbiology and Pathology.)

Objective: The study aimed to investigate the effects of quercetin on Aquaporin 1 (AQP1) translocation in high glucose condition and made an attempt to clarify the underlying mechanisms and provide new ideas for the treatment of diabetic cataract (DC)., Methods: The human lens epithelial line SRA01/04 cells were divided into groups mentioned below: normal glucose, high glucose with a specific time (0 h, 2 h, 4 h, 8 h, 12 h, 24 h), high glucose plus the phosphoinositide 3-kinase (PI3K) inhibitor LY294002, high glucose plus the mammalian target of rapamycin (mTOR) inhibitor rapamycin, and high glucose plus quercetin with different doses (2 μmol/L, 4 μmol/L and 8 μmol/L). The western blotting assay was used to detect the protein kinase B (Akt), phosphorylated protein kinase B (p-Akt), mammalian target of rapamycin (m- TOR), phosphorylated mammalian target of rapamycin (p-mTOR) and AQP1. Real-time polymerase chain reaction (RT-PCR) was used to detect the expression of AQP1. A Membrane and Cytosol Protein Extraction Kit was applied to separate membrane proteins. Immunofluorescence assay was performed to evaluate the expression and location of AQP1. The effect of quercetin on the expression of AQP1 and PI3K/Akt/mTOR signaling was detected., Results: AQP1 protein was found to be significantly increased in 24 hour when exposed to high glucose condition (P<0.01). LY294002 and rapamycin inhibited PI3K/Akt/mTOR and AQP1 expression (P<0.01), preventing the change of AQP1 location in the SRA01/04 plasma membrane (P<0.01). This effect was further proved by immunofluorescence. In different doses of quercetin groups (2 μmol/L, 4 μmol/L and 8 μmol/L), the phosphorylation of mTOR and Akt were decreased and AQP1 in the membrane was changed compared with high glucose group (P<0.01)., Conclusion: Quercetin significantly decreased the AQP1 elevation and prevented the change of AQP1 location through inhibiting the activation of the PI3K/Akt/mTOR signaling in high-glucose-- cultured SRA01/04 cells, which might have the preventable and inhibitory effects on the early development of diabetic cataract. The specific pathophysiological role of quercetin still needs to be verified., (Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.net.)

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.)

Bile secretion by hepatocytes is an osmotic process. The output of bile salts and other organic anions (e.g. glutathione), through the bile salt transporter BSEP/ABCB11 and the organic anion transporter MRP2/ABCC2, respectively, are considered to be the major osmotic driving forces for water secretion into bile canaliculi mainly via aquaporin-8 (AQP8) channels. The down-regulated canalicular expression of these key solute transporters and AQP8 would be a primary event in the establishment of hepatocellular cholestasis. Recent studies in animal models of hepatocellular cholestasis show that the hepatic delivery of AdhAQP1, an adenovector encoding for the archetypical water channel human aquaporin-1 (hAQP1), improves bile secretion and restores to normal the elevated serum bile salt levels. AdhAQP1-transduced hepatocytes show that the canalicularly-expressed hAQP1 not only enhances osmotic membrane water permeability but also induces the transport activities of BSEP/ABCB11 and MRP2/ABCC2 by redistribution in canalicular cholesterol-rich microdomains likely through interactions with the cholesterol-binding protein caveolin-1. Thus, the hepatic gene transfer of hAQP1 improves the bile secretory failure in hepatocellular cholestasis by increasing both biliary output and choleretic efficiency of key osmotic solutes, such as, bile salts and glutathione. The study of hepatocyte aquaporins has provided new insights into the mechanisms of bile formation and cholestasis, and may lead to innovative treatments for cholestatic liver diseases., (Copyright © 2021 Elsevier B.V. and Société Française de Biochimie et Biologie Moléculaire (SFBBM). All rights reserved.)

Although several studies have shown that release of water channel proteins, aquaporin 1 (AQP1) and AQP2 in urinary extracellular vesicles (uEV-AQP1 and -AQP2), were altered in experimental kidney injury models, their release in human chronic kidney disease (CKD) has been largely unexplored. The aim of the present study was to clarify whether the release of uEV-AQP1 and -AQP2 is altered in patients with CKD. Urine samples were collected from 15 healthy volunteers (normal group) and 62 CKD patients who were categorized into six glomerular filtration rate (GFR) categories (G1, G2, G3a, G3b, G4, and G5) in between 2005 and 2016 at Miyazaki Prefectural Miyazaki Hospital, Japan. uEV-proteins were evaluated by immunoblot analysis. The release of AQP1 and AQP2 were significantly decreased in patients with both CKD G4 and G5, in comparison with the normal group. The area under the receiver operating characteristic (ROC) curve (AUC) values for AQP1 and AQP2 in patients with CKD G4 and G5 were 0.926 and 0.881, respectively. On the other hand, the AUC values in patients with CKD G1-G3 were 0.512 for AQP1 and 0.680 for AQP2. Multiple logistic regression analysis showed that AQP1 and AQP2 in combination were useful for detecting CKD G4 and G5, with a higher AUC value of 0.945. These results suggest that the release of uEV-AQP1 and -AQP2 was decreased in patients with CKD G4 and G5, and these proteins might be helpful to detect advanced CKD., (© 2021 The Authors. Physiological Reports published by Wiley Periodicals LLC on behalf of The Physiological Society and the American Physiological Society.)

Rheumatoid arthritis (RA) is an autoimmune disease that causes inflammation of the synovial membrane ultimately leading to permanent damage in the affected joints. For this study, synovial fluids from 16 patients diagnosed with either RA or osteoarthritis (OA) were used to examine volume regulation and cooperative water channels, both of which are involved in the cytotoxic edema identified in RA-fibroblast-like synoviocytes (FLS). The osmolarity and inflammatory cytokine interleukin (IL)-6 of synovial fluids from RA patients were mildly enhanced compared to that from OA patients. RA-FLS demonstrated the enhanced property of regulatory volume increase in response to IL-6 and synovial fluids from RA patients. Although there was no difference in the protein expression of the volume-associated protein sodium-potassium-chloride cotransporter1 (NKCC1), its activity was increased by treatment with IL-6. Membrane localization of NKCC1 was also increased by IL-6 treatment. Additionally, both the protein and membrane expressions of aquaporin-1 were increased in RA-FLS by IL-6 stimulation. The IL-6-mediated enhanced osmotic sensitivity of RA-FLS likely involves NKCC1 and aquaporin-1, which mainly constitute the volume-associated ion transporter and water channel elements. These results suggest that RA-FLS provide enhanced electrolytes and concomitant water movement through NKCC1 and aquaporin-1, thereby inducing cellular swelling ultimately resulting in cytotoxic edema. Attenuation of cytotoxic edema and verification of its related mechanism will provide novel therapeutic approaches to RA treatment within the scope of cytotoxic edema., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2021 Ji, Ryu and Hong.)

Peritoneal membrane dysfunction and the resulting ultrafiltration failure are the major disadvantages of long-term peritoneal dialysis (PD). It becomes increasingly clear that mesothelial cells play a vital role in the pathophysiological changes of the peritoneal membrane. Matrix metalloproteinases (MMPs) function in the extracellular environment of cells and mediate extracellular matrix turnover during peritoneal membrane homeostasis. We showed here that dialysate MMP-7 levels markedly increased in the patients with PD, and the elevated MMP-7 level was negatively associated with peritoneal ultrafiltration volume. Interestingly, MMP-7 could regulate the cell osmotic pressure and volume of human peritoneal mesothelial cells. Moreover, we provided the evidence that MMP-7 activated mitogen-activated protein kinases (MAPKs)-extracellular signal-regulated kinase 1/2 (ERK) pathway and subsequently promoted the expression of aquaporin-1 (AQP-1) resulting in the change of cell osmotic pressure. Using a specific inhibitor of ERK pathway abrogated the MMP-7-mediating AQP-1 up-regulation and cellular homeostasis. In summary, all the findings indicate that MMP-7 could modulate the activity of peritoneal cavity during PD, and dialysate MMP-7 might be a non-invasive biomarker and an alternative therapeutic target for PD patients with ultrafiltration failure., (© 2021 The Authors. Journal of Cellular and Molecular Medicine published by Foundation for Cellular and Molecular Medicine and John Wiley & Sons Ltd.)

Several studies have indicated that a vulnerability in the development and regulation of brain function is involved in sudden infant death syndrome (SIDS). The aim of this study was to investigate the genes encoding the brain aquaporins (AQPs) AQP1 and AQP9 in SIDS. The hypothesis was that specific variants of these genes are part of the genetic vulnerability predisposing infants to sudden unexpected death. The study included 168 SIDS cases with a median age of 15.5 (range 2-52) weeks and 372 adolescent/adult deceased controls with a median age of 44 (range 11-91) years. In the AQP1 gene, the rs17159702 CC/CT genotypes were found to be associated with SIDS (p = 0.02). In the AQP9 gene, the combination of a TT genotype of rs8042354, rs2292711 and rs13329178 was more frequent in SIDS cases than in controls (p = 0.03). In the SIDS group, an association was found between genetic variations in the AQP1 gene and maternal smoking and between the 3xTT combination in the AQP9 gene and being found lifeless in a prone position. In conclusion, this study adds further evidence to the involvement of brain aquaporins in SIDS, suggesting that specific variants of AQP genes constitute a genetic predisposition, making the infant vulnerable to sudden death together with external risk factors and probably other genetic factors.

Propranolol, a nonselective β-adrenergic receptor (ADRB) antagonist, is the first-line therapy for severe infantile hemangiomas (IH). Since the incidental discovery of propranolol efficacy in IH, preclinical and clinical investigations have shown evidence of adjuvant propranolol response in some malignant tumors. However, the mechanism for propranolol antitumor effect is still largely unknown, owing to the absence of a tumor model responsive to propranolol at nontoxic concentrations. Immunodeficient mice engrafted with different human tumor cell lines were treated with anti-VEGF bevacizumab to create a model sensitive to propranolol. Proteomics analysis was used to reveal propranolol-mediated protein alteration correlating with tumor growth inhibition, and Aquaporin-1 (AQP1), a water channel modulated in tumor cell migration and invasion, was identified. IH tissues and cells were then functionally investigated. Our functional protein association networks analysis and knockdown of ADRB2 and AQP1 indicated that propranolol treatment and AQP1 down-regulation trigger the same pathway, suggesting that AQP1 is a major driver of beta-blocker antitumor response. Examining AQP1 in human hemangioma samples, we found it exclusively in a perivascular layer, so far unrecognized in IH, made of telocytes (TCs). Functional in vitro studies showed that AQP1-positive TCs play a critical role in IH response to propranolol and that modulation of AQP1 in IH-TC by propranolol or shAQP1 decreases capillary-like tube formation in a Matrigel-based angiogenesis assay. We conclude that IH sensitivity to propranolol may rely, at least in part, on a cross talk between lesional vascular cells and stromal TCs., Competing Interests: Competing interest statement: A patent has been granted for the use of beta-blockers in infantile capillary hemangiomas, with A.T. and C.L.-L. as inventors and Bordeaux University and Bordeaux University Hospital as owners of the patent. None of the authors have any other financial interests related to this work.

Objective: This study aimed to explore the relationship between diabetic xerostomia and changes in aquaporin-1 (AQP1), aquaporin-5 (AQP5), and aquaporin-8 (AQP8) expression in the submandibular glands (SMGs), to further study the pathogenesis of diabetic xerostomia and to observe the therapeutic effect of insulin (INS)., Methods: Thirty SD rats were randomized equally into 3 groups: control group, diabetic model (DM) group and insulin (INS) group (n=10, respectively). The control group received no treatment. DM group and INS group were induced by a high-fat diet and streptozotocin intraperitoneal injection. After establishment of a diabetic rat model, the rats in INS group were treated with insulin. Then all rats were fed continuously with ordinary diet for 2 months. H&E staining was used to describe morphologic changes in the SMGs of rats. Immunohistochemistry was used to analyze the expressions and localization of AQP1, AQP5, and AQP8 in the SMGs. Computer image analysis was used to detect the mean optical density (MOD) values of AQP1, AQP5, and AQP8 expression, and changes in the diameters of acini and ducts., Results: The acini were mildly atrophied and the acinar cells were rearranged in an irregular way. The morphology of insulin-administered diabetic SMGs was similar to that of the control group. The acinar average circumference and GCT average diameter in DM group were significantly reduced (P<0.05). The acinar average circumference and GCT average diameter of INS group were significantly increased (P<0.05). The expressions of AQP1, AQP5, and AQP8 were significantly reduced in DM group (P<0.05). The expressions of AQP1, AQP5, and AQP8 in INS group were significantly increased (P<0.05)., Conclusion: The decreased expressions of AQP1, AQP5, and AQP8 led to decreased salivary secretion of SMGs in diabetic rats, which may be involved in the pathogenesis of diabetic xerostomia. Insulin could up-regulate the expressions of AQP1, AQP5 and AQP8, and play a protective role in the secretory function of diabetic SMGs., Competing Interests: None., (IJCEP Copyright © 2021.)

Aquaporin 1 (AQP1), a transmembrane protein that forms water channels, has previously been shown to facilitate growth and progression of many types of tumors by modulating tumor cell migration, proliferation and angiogenesis. Here, we determined the impact of AQP1 expression in the tumor environment on the progression of brain tumors. Primary microglia from wild type(WT) and AQP1 knockout(KO) mice were used to test AQP1 effect on microglia function by using Western blot, quantative PCR, in an experimental in vivo mouse glioma model and organotypic brain slice culture. Deletion of AQP1 in the host tissue significantly reduced the survival of the mice implanted with GL261 glioma cells. The density of glioma-associated microglia/macrophages was almost doubled in AQP1KO mice. We found that factors secreted from GL261 cells decrease microglial AQP1 expression via the MEK/ERK pathway, and that inhibition of this pathway with Trametinib reduced tumor growth and prolonged the survival of tumor bearing mice, an effect which required the presence of microglia. Deletion of AQP1 in cultured microglia resulted in an increase in migratory activity and a decrease in TLR4-dependent innate immune responses. Our study demonstrates a functional relevance of AQP1 expression in microglia and hints to AQP1 as a potential novel target for glioma therapy., (Copyright © 2020 Elsevier Inc. All rights reserved.)

Background: This study aimed to investigate the long-term prognosis value of serum galectin-3, aquaporin (AQP)-1 and AQP-3 in young patients with colon cancer., Methods: A total of 100 young patients with colon cancer, 100 cases of benign colon and 100 healthy people were collected. All colon cancer patients were followed up for 42 months., Results: Compared with the benign lesion group and the control group, preoperative serum galectin-3, AQP-1 and AQP-3 concentrations were significantly increased in patients with colon cancer ( P  <   0.05). The immunohistochemistry scores of galectin-3, AQP-1 and AQP-3 in colon cancer patients were positively correlated with serum galectin-3, AQP-1 and AQP-3 concentrations ( P  <   0.05). Serum galectin-3, AQP-1 and AQP-3 concentrations were positively correlated with TNM staging (galectin-3: r Pearson  = 0.502, P  <   0.001; AQP-1: r Pearson  = 0.415, P  <   0.001; AQP-3: r Pearson  = 0.454, P  <   0.001) and differentiation (galectin-3: r Pearson  = 0.377, P  = 0.004; AQP-1: r Pearson  = 0.411, P  = 0.001; AQP-3: r Pearson  = 0.483, P  <   0.001). Receiver operator characteristic curve (ROC) analysis showed that the area under ROC curve (AUC) of the combination of galectin-3, AQP-1 and AQP-3 in distinguishing colon cancer was 0.907. The sensitivity in the parallel mode was 87.6%, and the specificity in the serial mode was 98.2%. Compared with the low galectin-3 group, low AQP-1 group and low AQP-3 group, the survival time of patients in the high galectin-3 group (χ 2  = 13.929, P  <   0.001), high AQP-1 group (χ 2  = 10.157, P  = 0.001) and high AQP-3 group (χ 2  = 4.364, P  = 0.037) were significantly shortened., Conclusion: Galectin-3 combined with AQP-1 and AQP-3 had important value in the identification of young patients with colon cancer and was of great value in evaluating long-term prognosis.

Objective: To investigate the therapeutic roles of hyperbaric oxygen exposure on high-altitude pulmonary edema and to determine whether aquaporin-1 and aquaporin-5 were involved in the pathogenesis of HAPE in rats., Methods: Rats were divided into 5 groups: The control group, the HAPE group (HAPE model), the HBO group (hyperbaric oxygen exposure), the NBO group (normobaric oxygen exposure), and the NA group (normal air exposure). Western blot and real-time PCR were used to analyze the pulmonary expressions of AQP1 and AQP5. The wet-to-dry (W/D) weight ratio and the morphology of the lung were also examined., Results: The lung W/D weight ratio in the HAPE group was increased compared with the control group. The injury score in the HBO group was noticeably lower than that in the control group. The mRNA and proteins expressions of AQP1 and AQP5 were significantly downregulated in the HAPE group., Conclusions: Oxygen exposure alleviated high-altitude hypobaric hypoxia-induced lung injury in rats. Additionally, HBO therapy had significant advantage on interstitial HAPE., Competing Interests: Declaration of Conflicting Interests: The author(s) declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article., (© The Author(s) 2020.)

Atherosclerosis starts with transmural (transwall) pressure-driven advective transport of blood-borne low-density lipoprotein (LDL) cholesterol across rare endothelial cell (EC) monolayer leaks into the arterial subendothelial intima (SI) wall layer where they can spread, bind to extracellular matrix and seed lesions. The local SI LDL concentration, which governs LDL's binding kinetics, depends on the overall diluting transmural liquid flow. Transmural pressures typically compress the SI at physiological pressures, which keeps this flow low. Nguyen et al. (2015) showed that aortic ECs express the water channel protein aquaporin-1 (AQP1) and the transEC (δP) portion of the transmural (ΔP) pressure difference drives, in parallel, water across AQP1s and plasma across interEC junctions. Since the lumen is isotonic, selective AQP1-mediated water flow should quickly render the ECs' lumen side hypertonic and the SI hypotonic; resulting transEC oncotic pressure differences, δπ, should oppose δP and quickly halt transEC flow. Yet Nguyen et al.'s (2015) transAQP1 flows persist for hours. To resolve this paradox, we extend our fluid filtration theory Joshi et al. (2015) to include mass transfer for oncotically active solutes like albumin. This addition nonlinearly couples mass transfer, fluid flow and wall mechanics. We simultaneously solve these problems at steady state. Surprisingly it finds that media layer filtration causes steady SI to exceed EC glycocalyx albumin concentration. Thus δπ reinforces rather than opposes δP, i.e., it sucks water from, rather than pushing water into the lumen from the SI. Endothelial AQP1s raise the overall driving force for flow across the EC above δP, most significantly at pressures too low to compress the SI, and they increase the ΔP needed for SI compression. This suggests the intriguing possibility that increasing EC AQP1 expression can raise this requisite compression pressure to physiological values. That is, increasing EC AQP1 may decompress the SI at physiological pressures, which would significantly increase SI thickness, flow and subsequently SI LDL dilution. This could retard LDL binding and delay preatherosclerotic lesion onset. The model also predicts that glycocalyx-degrading enzymes decrease overall transEC driving forces and thus lower, not raise, transmural water flux., (Copyright © 2020 Elsevier Ltd. All rights reserved.)

(1) Background: Lipopolysaccharide (LPS)-induced systemic inflammation is associated with septic acute kidney injury (AKI). We investigated the time-dependent miRNA expression changes in the kidney caused by LPS. (2) Methods: Male outbred NMRI mice were injected with LPS and sacrificed at 1.5 and 6 h (40 mg/kg i.p., early phase, EP) or at 24 and 48 h (10 mg/kg i.p., late phase, LP). The miRNA profile was established using miRCURY LNA™ microarray and confirmed with qPCR. Total renal proteome was analyzed by LC-MS/MS (ProteomeXchange: PXD014664). (3) Results: Septic AKI was confirmed by increases in plasma urea concentration and in renal TNF-α and IL-6 mRNA expression. Most miRNAs were altered at 6 and 24 h and declined by 48 h. In EP miR-762 was newly identified and validated and was the most elevated miRNA. The predicted target of miR-762, Ras related GTPase 1B (Sar1b) was downregulated. In LP miR-21a-5p was the most influenced miRNA followed by miR-451a, miR-144-3p, and miR-146a-5p. Among the potential protein targets of the most influenced miRNAs, only aquaporin-1, a target of miR-144-3p was downregulated at 24 h. (4) Conclusion: Besides already known miRNAs, septic AKI upregulated miR-762, which may regulate GTP signaling, and miR-144-3p and downregulated its target, aquaporin-1.

Background: Aquaporin (AQP) 1 expression has been linked with tumor malignancy but its role in glioblastoma (GBM), a lethal glioma, remains to be clarified., Methods: AQP1 expression was examined in 33 human GBM specimens by immunohistochemistry. GBM cells (U251 and U87) that stably express AQP1 were established and used for cellular proliferation, migration, invasion, and vascular tube formation assays. The GeneChip assay was used to identify differentially expressed genes in AQP1-expressing cells., Results: AQP1 was expressed only in tumor cells. AQP1 dose-dependently accelerated cell migration and invasion, but not proliferation, in GBM cell lines. AQP1 also upregulated cathepsin B, focal adhesion kinase and activities of matrix metalloproteinase 9. AQP1 in GBM cells induced wall thickness of ECV304, vascular endothelial cells, in a contact-dependent manner. Downregulation of thrombospondin type 1 domain containing 7A (THSD7A) was identified in AQP1-expressing GBM cells in vitro, and was negatively correlated with AQP1 expression in human GBM specimens., Conclusion: AQP1 is involved in tumor malignancy by facilitating the migration and invasion of GBM cells, and promoting the formation of vascular beds that are characteristic of GBM by downregulating THSD7A., (© 2020 The Authors. Cancer Medicine published by John Wiley & Sons Ltd.)

Water influx through aquaporin-1 (AQP-1) has been linked to the ability of different cell types to migrate, and therefore plays an important part in processes like metastasis and angiogenesis. Since the erythroid growth factor erythropoietin (Epo) is now recognized as an angiogenesis promoter, we investigated the participation of AQP-1 as a downstream effector of this cytokine in the migration of endothelial cells. Inhibition of AQP-1 with either mercury ions (Hg 2+ ) or a specific siRNA led to an impaired migration of EA.hy926 endothelial cells exposed to Epo (wound-healing assays). Epo also induced the expression of AQP-1 at mRNA and protein levels, an effect which was dependent on the influx of extracellular calcium through L-type calcium channels as well as TRPC3 channels. The relationship between Epo and AQP-1 was further confirmed at shorter exposure times, as the cytokine was unable to trigger calcium influxes in cells where AQP-1 had previously been knocked down. Moreover, Epo promoted changes in the subcellular localization of AQP-1 as well as rearrangements in the actin cytoskeleton, which are consistent with a migratory phenotype. Worthy of note, carbamylated erythropoietin (cEpo), the non-erythropoietic and non-promigratory derivative of Epo, was incapable of AQP-1 modulation. The therapeutical implications of aquaporin targeting in angiogenesis-related diseases highlight the importance of the present results in the context of the relationship between AQP-1 and Epo., (Copyright © 2019 Elsevier B.V. All rights reserved.)

Objective: This study was designed to investigate the role of AQP1 in the development of LPS-induced AKI and its potential regulatory mechanisms in the inflammatory responses of macrophages., Methods: Male Wistar rats were injected intraperitoneally with LPS, and biochemical and histological renal damage was assessed. The levels of inflammatory mediators, macrophage markers and AQP1 in blood and kidney tissues were assessed by ELISA. RTPCR was used to assess changes in the relative levels of AQP1 mRNA induced by LPS. Western blot and immunofluorescence analyses were performed to assay the activation of the p38 MAPK and NF-κB pathways, respectively. The same detection methods were used in vitro to determine the regulatory mechanisms underlying AQP1 function., Results: AQP1 mRNA levels were dramatically decreased in AKI rats following the increased expression of inflammatory factors. In vitro experiments demonstrated that silencing the AQP1 gene increased inflammatory mediator secretion, altered the classical activation of macrophages, greatly enhanced the phosphorylation of p38 and accelerated the translocation of NF-κB. Furthermore, these results were blocked by doramapimod, a p38 inhibitor. Therefore, these effects were mediated by the increased phosphorylation of p38 MAPK., Conclusion: Our results suggest that altered AQP1 expression may be associated with the development of inflammation in AKI. AQP1 plays a protective role in modulating acute renal injury and can attenuate macrophage-mediated inflammatory responses by downregulating p38 MAPK activity in LPS-induced RAW264.7 cells. The pharmacological targeting of AQP1-mediated p38 MAPK signalling may provide a novel treatment approach for AKI.

Multidrug resistance-associated protein 2 (MRP2/ABCC2), a hepatocyte canalicular transporter involved in bile secretion, is downregulated in cholestasis triggered by lipopolysaccharide. The human aquaporin-1 (hAQP1) adenovirus-mediated gene transfer to liver improves cholestasis by incompletely defined mechanisms. Here we found that hAQP1 did not affect MRP2/ABCC2 expression, but significantly increased its transport activity assessed in situ with endogenous and exogenous substrates, likely by a hAQP1-induced increase in canalicular membrane cholesterol amount. Our results suggest that hAQP1-induced MRP2/ABCC2 activation contributes to the cholestasis improvement., (Copyright © 2019 Elsevier B.V. and Société Française de Biochimie et Biologie Moléculaire (SFBBM). All rights reserved.)

The choroid plexus (ChP) is involved in the production of cerebrospinal fluid (CSF) and is intimately related to CSF physiopathology. Aquaporin-1 (AQP1) is the water channel directly implicated in CSF production and a potential therapeutic target in the management of CSF circulation disorders. Pathologies that present ventriculomegaly are associated with defective CSF turnover and AQPs are involved in both the production and reabsorption of CSF. This work examines the levels of AQP1 and its dynamics in ventriculomegaly conditions such as congenital hydrocephalus (communicating and obstructive) or type II lissencephaly versus control. We specifically address the expression of AQP1 in the CSF of 16 term-pregnancy infants where it was found to be significantly increased in obstructive cases when compared with communicating hydrocephalus or control patients. We also defined histologically the expression of AQP1 in the ChP from 6 nonsurvival preterm-pregnancy infants ranging ages between 20 and 25 gestational weeks in which AQP1 was mainly expressed at the apical pole of the ChP epithelium (ChPE) in control and lissencephalic patients. AQP1 expression from the Chiari malformation case showed an inverted polarity being expressed in the basal pole of the ChPE colocalizing with the glucose transporter 1 where this transporter is naturally located., (© 2019 American Association of Neuropathologists, Inc. All rights reserved.)

Background: Diuresis has been observed within a week following renal transplantation, suggesting that the procedure causes acute disturbance of renal water homeostasis. Aquaporin (AQP) 1 and AQP2, important proteins for renal water reabsorption, have been identified in urinary extracellular vesicles (uEV-AQP1 and -AQP2), and experimental studies have shown that the presence of uEV-AQP1 and -AQP2 may be an indicator of their levels of expression in the kidney. However, the release patterns of uEV-AQP1 and -AQP2 during the acute phase following renal transplantation are largely unknown., Methods: In this study, we examined the release of uEV-AQP1 and -AQP2 in recipients until 6 days (day 6) after renal transplantation. At Miyazaki prefectural Miyazaki Hospital, Japan, uEVs were obtained from 7 recipients, all of whom had received renal allografts from living donors. uEVs were isolated by differential centrifugation., Results: Immunoblotting analysis showed that the release of uEV-AQP2 was significantly decreased on day 1 in comparison with a control sample (from 3 healthy volunteers), accompanied by high urine output and low urine osmolality. Thereafter, the level increased gradually to the control level by day 6. The release pattern of uEV-AQP1 was similar to that of uEV-AQP2, but the levels did not reach statistical significance in comparison with the control level at any of the time points examined. Evaluation of the relationship between urinary osmolality and uEV-AQPs revealed a significant correlation for uEV-AQP2, but not for uEV-AQP1., Conclusion: These results indicate that acute diuresis after renal transplantation might be due to a decrease in the renal expression of AQP2, whose level can be estimated from the amount released in uEVs.

Escin, a natural triterpene saponin mixture obtained from the horse chestnut tree (Aesculus hippocastanum), has been used for the treatment of chronic venous insufficiency (CVI), hemorrhoids, and edema. However, it is unclear how escin protects against endothelial barrier dysfunction induced by pro-inflammatory high mobility group protein 1 (HMGB1). Here, we report that escin can suppress (a) HMGB1-induced overexpression of the aquaporin-1 (AQP1) water channel in endothelial cells and (b) HMGB1-induced increases in endothelial cell permeability. This is the first report that escin inhibits AQP1 and alleviates barrier dysfunction in HMGB1-induced inflammatory response., (© 2019 The Authors. Published by FEBS Press and John Wiley & Sons Ltd.)

To investigate the effect of miR-223 on thyroid cancer cells, further to study its potential mechanisms. The difference in miR-223 expression between normal thyroid Nthy-ori3-l cells and thyroid cancer SW579 cells was detected by PCR. The miR-223 overexpression and silencing vector transfection were verified by qRT-PCR. To further investigate the role of miR-223 in AQP-1, the AQP-1 siRNA vector was transfected on the basis of transfection of miR-223 inhibitor vector. The cell proliferation was detected by plate cloning, MTT, and cellular immunofluorescence assays. Cell cycle and apoptosis were detected by flow cytometry. Western blot was used to detect the expression of AQP-1 protein. The expression of miR-223 in SW579 cells was higher than that in normal cells. After transfection with miR-223 mimic, miR-223 expression was increased in SW579 cells. MiR-223 inhibitor transfection can inhibit SW579 cells proliferation, promote apoptosis, and inhibit cell cycle G0/G1 arrest. The SW579 cells proliferation was decreased, and the apoptosis rate was increased after transfection of AQP-1 silencing vector. Compared with the AQP-1 siRNA group, the SW579 cells proliferation rate was further reduced, and the apoptosis rate was significantly increased after co-transfection of miR-223 silencing vector and AQP-1 silencing vector. AQP-1 protein was highly expressed in SW579 cells, and miR-223 inhibitor can down-regulate the expression of APQ-1 protein. The expression AQP-1 protein was significantly reduced after transfected with AQP-1 silencing vector. Inhibition of miR-223 expression could suppress proliferation and promote apoptosis of SW579, and its mechanism is related to down-regulation of APQ-1 protein expression.

Background: To investigate the expression of Matrix Metalloproteinases 2 and aquaporin-1 in corneoscleral junction and explore the mechanism of trabecular damageafter angle-closure., Methods: Thirty New Zealand white rabbits were randomly assigned into 2 groups, theexperimental group (Group 1) including twenty five rabbits and the control group (Group 2) including 5 rabbits. The rabbits in the experimental group were used to establish angle-closure models, and the rabbits in the control group were not subjected to any operation. All the rabbits were followed by slit lamp microscopy, Tonopen tonometer, and anterior segment optical coherent tomography (AS-OCT). The expressions of metalloproteinase MMP-2, aquaporin-1, and tissue inhibitors of metalloproteinase-2 in corneoscleral junctionwere evaluatedin both groups byimmunofluorescence, quantitative reverse-transcription polymerase chain reaction (qRT-PCR), and enzyme-linked immunosorbent assay (ELISA)., Results: Slit-lamp examination showed that angle-closure model was successfully established in twenty rabbits. The extent of angle-closure was about 2 to 4 clock hours in all the rabbit models, but the intraocular pressure (IOP) of the rabbits distributed from 8.57 to 15.25 mmHg and no significant high IOP was found in the follow-up period. The AQP-1-positive cells mainly located in Schlemm's canal, the inner surface of trabecular meshwork (TM), and the surface of iris, which began to decline on 1 month after angle-closure. MMP2 staining was diffuse in trabecular meshwork and iris. Immunofluorescence signal of MMP2 was strong within 1 month after angle-closure, and subsequently became weak. qRT-PCR and ELISA showed that the expression of MMP-2 and TIMP-2 increased within 1 month after angle-closure and then declined gradually. The AQP-1 levels showed slightly declined on 1 month after angle-closure., Conclusions: Altered levels of MMPs, TIMPs, and AQP-1 were found in the area of angle-closure, which may be involved in the damage of TM and Schlemm's canal after angle-closure.

Introduction: Hydrocephalus is a common complication of subarachnoid haemorrhage (SAH). As transmembrane water channels, aquaporins 1 and 4 (AQP1 and AQP4) are involved in the pathogenesis of hydrocephalus. We aimed to assess the association between the expressions of AQP1 and AQP4 and the severity and duration of hydrocephalus after SAH., Material and Methods: A double haemorrhage model by injection of autologous blood into the cisterna magna was used to induce SAH in rats. Sham rats received the same procedures, but with the injection of normal saline. The SAH group was divided into the SAH with hydrocephalus group and SAH without hydrocephalus group after identifying hydrocephalus histologically. AQP1 and AQP4 in ventricle regions were detected by immunofluorescence, quantitative polymerase chain reaction (qPCR) and western blot., Results: Hydrocephalus was the most severe at day 3 after SAH. AQP1 and AQP4 mRNA and protein levels increased at day 1 and peaked at day 3. The SAH with hydrocephalus group had a higher expression of AQP1 and AQP4 than the SAH without hydrocephalus group. Higher AQP1 levels were found at the apical and basolateral membrane of the choroid plexus epithelium, while higher AQP4 levels were found in the ependymal cells. A positive correlation between the relative lateral ventricle area and the ratio of AQP1/AQP4 proteins was identified., Conclusions: AQP1 and AQP4 are remarkably correlated with the severity of hydrocephalus induced by SAH. AQP1 and AQP4 are potential drug targets for developing therapeutic strategies against hydrocephalus.

Objective: Aquaporin 1 (AQP-1) is a water channel protein found in cell membranes, whose expression has been considered an independent favourable prognostic factor in pleural malignant mesothelioma (MM). The aim of this study was to evaluate the expression of AQP-1 and its prognostic value in a series of pleural MM effusions, from a geographical area with high concentrations of fluoro-edenite (FE)., Methods: We selected 25 MM cases from Biancavilla (Italy), an area with high environmental concentrations of FE. Cytological samples, cell-blocks (CB), clinical and follow-up data were available for all cases. Immunohistochemistry for calretinin, CK5/6, WT1, CK7 and TTF1 was used on CB sections to confirm the cytological diagnosis of MM. Immunohistochemistry for AQP-1 was performed and high expression was defined when ≥50% of tumour cells showed linear and circumferential membranous staining., Results: The cohort included 16 men and nine women (median age: 67.5 years; range: 49-88 years). The median survival was 14 months (range 1.5-60 months), with a significant value (P = 0.006). All cases have been histologically confirmed and classified as epithelioid (16 cases), biphasic (seven cases) and sarcomatoid (two cases). AQP-1 high expression has been observed in 16 cases. Comparing AQP-1 high expression to the survival of corresponding patients, a significant association with a slight increased overall survival of 12 months has been demonstrated. Nine patients with a AQP-1 score less than 50% showed a shorter median overall survival (7 months)., Conclusions: AQP-1 high expression is detectable on cytological samples of FE-induced MM with a prognostic value., (© 2018 John Wiley & Sons Ltd.)

Aquaporin-1 (AQP1), a transmembrane pore-forming molecule, facilitates the rapid movement of water and small solutes across cell membranes. We have previously shown that bacopaside II, an extract from the medicinal herb Bacopa monnieri , blocks the AQP1 water channel and impairs migration of cells that express AQP1. The aim of this study was to further elucidate the anti-tumour potential of bacopaside II in colon cancer cells. Expression of AQP1 in HT-29, SW480, SW620 and HCT116 was determined by quantitative PCR and western immunoblot. Cells were treated with bacopaside II, and morphology, growth, autophagy, cell cycle and apoptosis assessed by time-lapse microscopy, crystal violet, acridine orange, propidium iodide (PI) and annexin V/PI staining respectively. AQP1 expression was significantly higher in HT-29 than SW480, SW620 and HCT116. Bacopaside II significantly reduced growth at ≥20 µM for HT-29 and ≥15 µM for SW480, SW620 and HCT116. Inhibition of HT-29 at 20 µM was primarily mediated by G0/G1 cell cycle arrest, and at 30 µM by G2/M arrest and apoptosis. Inhibition of SW480, SW620 and HCT116 at ≥15 µM was mediated by G2/M arrest and apoptosis. These results are the first to show that bacopaside II inhibits colon cancer cell growth by inducing cell cycle arrest and apoptosis.

Background Osmosis drives transcapillary ultrafiltration and water removal in patients treated with peritoneal dialysis. Crystalloid osmosis, typically induced by glucose, relies on dialysate tonicity and occurs through endothelial aquaporin-1 water channels and interendothelial clefts. In contrast, the mechanisms mediating water flow driven by colloidal agents, such as icodextrin, and combinations of osmotic agents have not been evaluated. Methods We used experimental models of peritoneal dialysis in mouse and biophysical studies combined with mathematical modeling to evaluate the mechanisms of colloid versus crystalloid osmosis across the peritoneal membrane and to investigate the pathways mediating water flow generated by the glucose polymer icodextrin. Results In silico studies showed that deletion of aquaporin-1 did not influence osmotic water transport induced by icodextrin but did affect that induced by crystalloid agents. Water flow induced by icodextrin was dependent upon the presence of large, colloidal fractions, with a reflection coefficient close to unity, a low diffusion capacity, and a minimal effect on dialysate osmolality. Combining crystalloid and colloid osmotic agents in the same dialysis solution strikingly enhanced water and sodium transport across the peritoneal membrane, improving ultrafiltration efficiency over that obtained with either type of agent alone. in vivo studies showed that deletion of aquaporin-1 did not influence osmotic water transport induced by icodextrin but did affect that induced by crystalloid agents. Water flow induced by icodextrin was dependent upon the presence of large, colloidal fractions, with a reflection coefficient close to unity, a low diffusion capacity, and a minimal effect on dialysate osmolality. Combining crystalloid and colloid osmotic agents in the same dialysis solution strikingly enhanced water and sodium transport across the peritoneal membrane, improving ultrafiltration efficiency over that obtained with either type of agent alone. Conclusions These data cast light on the molecular mechanisms involved in colloid versus crystalloid osmosis and characterize novel osmotic agents. Dialysis solutions combining crystalloid and colloid particles may help restore fluid balance in patients treated with peritoneal dialysis., (Copyright © 2018 by the American Society of Nephrology.)

The Cl - /HCO 3 - exchanger band 3 is functionally relevant to blood CO 2 transport. Band 3 is the most abundant membrane protein in human red blood cells (RBCs). Our understanding of its physiological functions mainly came from clinical cases associated with band 3 mutations. Severe reduction in band 3 expression affects blood HCO 3 - /CO 2 metabolism. What could happen physiologically if band 3 expression is elevated instead? In some areas of Southeast Asia, about 1-10% of the populations express GP.Mur, a glycophorin B-A-B hybrid membrane protein important in the field of transfusion medicine. GP.Mur functions to promote band 3 expression, and GP.Mur red cells can be deemed as a naturally occurred model for higher band 3 expression. This review first compares the functional consequences of band 3 at different levels, and suggests a critical role of band 3 in postnatal CO 2 respiration. The second part of the review explores the transport of water, which is the other substrate for intra-erythrocytic CO 2 transport). Despite that water is considered unlimited physiologically, it is unclear whether water channel aquaporin-1 (AQP1) abundantly expressed in RBCs is functionally involved in CO 3 - conversion (an essential step in blood CO 2 transport). Despite that water is considered unlimited physiologically, it is unclear whether water channel aquaporin-1 (AQP1) abundantly expressed in RBCs is functionally involved in CO 2 transport. Research in this area is complicated by the fact that the H 2 O/CO 2 -transporting function of AQP1 is replaceable by other erythrocyte channels/transporters (e.g., UT-B/GLUT1 for H 2 O; RhAG for CO 2 ). Recently, using carbonic anhydrase II (CAII)-filled erythrocyte vesicles, AQP1 has been demonstrated to transport water for the CAII-mediated reaction, CO 2(g) + H 2 O ⇌ HCO 3 - (aq) + H + (aq) . AQP1 is structurally associated with some population of band 3 complexes on the erythrocyte membrane in an osmotically responsive fashion. The current findings reveal transient interaction among components within the band 3-central, CO 2 -transport metabolon (AQP1, band 3, CAII and deoxygenated hemoglobin). Their dynamic interaction is envisioned to facilitate blood CO 2 respiration, in the presence of constantly changing osmotic and hemodynamic stresses during circulation.

The aim of the present study was to determine whether acetazolamide (Ace) treatment enhances the chemosensitivity of Hep-2 laryngeal cells to cisplatin (Cis). At the logarithmic growth phase, Hep-2 cells were treated with Ace, Cis or both, and cell viability was detected using an MTT assay. The degree of apoptosis was detected using flow cytometry. Expression levels of apoptosis-related proteins, including BCL2 apoptosis regulator (bcl-2), BCL2 associated X (bax) and caspase-3, and of proliferation-related proteins, including proliferating cell nuclear antigen (PCNA) and tumor protein p53 (P53), were detected using western blotting. mRNA expression levels of aquaporin-1 (AQP1) in each group were detected using reverse transcription-polymerase chain reaction. Compared with the drugs used alone, treatment with both Ace and Cis displayed synergistic effects on the growth inhibition and apoptosis induction in Hep-2 cells. The Ace/Cis combination decreased the expression of PCNA but increased the expression of p53. In addition, the combination treatment decreased the ratio of bcl-2/bax and increased the expression of caspase-3, as well as decreased the expression of AQP1. These results demonstrated that the combined use of Ace and Cis enhanced the chemosensitivity of laryngeal carcinoma cells.

Aristolochic acid I (AA-I), one of the main active components in Aristolochaia herbs, may induce aristolochic acid nephropathy (AAN). Renal interstitial fibrosis is one of the most typical features of AAN. To investigate the mechanism of Aristolochic acid I (AA-I) -induced renal epithelial-mesenchymal transition (EMT) and determine the role of aquaporin-1 (AQP1) in this process, we established an AA-I-induced EMT model in human proximal tubular epithelial cells (HK-2 cells). Morphological examination, MTT assay, and Western blot analysis were performed. Aquaporin 1 (AQP1) and several EMT-related proteins were detected, thereby suggesting the occurrence of AA-I-induced EMT. Two main pathways of transforming growth factor-β (TGF-β) signaling, namely, Smad-dependent and Smad-independent signaling pathways, were also detected. The results showed that the TGF-β / Smad-independent signaling pathways (β-catenin, Ras-Raf-Erk1/2 signaling pathways) were activated, and AQP1 expression was decreased during the AA-I induced EMT on HK-2 cells. With the presence of TGF-β1 receptor inhibitor (LY364947) and Erk1/2 inhibitor (PD98059), AQP1 expression was altered by PD98059, suggested that AQP1 could be adjusted by Erk1/2 signaling. Moreover, the inhibitory effect of AA-I on AQP1 was stronger than that of TGF-β1, suggested that AQP1 may be an important target on AAN clinical therapy., (© 2017 Wiley Periodicals, Inc.)

Acute kidney injury (AKI) is an important risk factor for the development of chronic kidney disease (CKD), and an alteration in renal water handling has been observed during the transition of AKI to CKD. Urinary exosomal release of aquaporin-1 (AQP1) and AQP2, important proteins for renal water handling, has recently been reported to predict their levels of renal expression. Therefore, we examined the patterns of urinary exosomal release of AQP1 and AQP2, and the exosomal marker proteins tumor susceptibility 101 protein (TSG101) and ALG-2 interacting protein X (Alix), in the acute and chronic phases following induction of AKI by renal bilateral ischemia/reperfusion (I/R) in rats. Blood tests and histological examinations indicated that AKI occurred before at 7 days after renal I/R ( day 7) and that renal fibrosis developed progressively thereafter. Immunoblotting demonstrated significant decreases in the urinary exosomal release of AQP1 and AQP2 during severe AKI. Urinary exosomal release of Alix and TSG101 was significantly increased on day 7. These data were also confirmed in rats with unilateral renal I/R causing more serious AKI. Urinary exosomal release of either the Ser-256- or Ser-269-phosphorylated form of AQP2, both of which are involved in apical trafficking of AQP2, was positively correlated with that of total AQP2. These results suggest that urinary exosomal release of AQP1 and AQP2 is reduced in I/R-induced AKI, whereas that of Alix and TSG101 is increased in the initial phase of renal fibrosis. Furthermore, apical trafficking of AQP2 appears to be related to urinary exosomal release of AQP2.

Aquaporin-1 (AQP1) is a proangiogenic water channel protein promoting endothelial cell migration. We previously reported that AQP1 silencing by RNA interference reduces angiogenesis-dependent primary tumour growth in a mouse model of melanoma. In this study, we tested the hypothesis that AQP1 inhibition also affects animal survival and lung nodule formation. Melanoma was induced by injecting B16F10 cells into the back of C57BL6J mice. Intratumoural injection of AQP1 siRNA and CTRL siRNA was performed 10 days after tumour cell implantation. Lung nodule formation was analysed after the death of the mice. Western blot was used to quantify HIF-1α, caspase-3 (CASP3) and metalloproteinase-2 (MMP2) protein levels. We found that AQP1 knock-down (KD) strongly inhibited metastatic lung nodule formation. Moreover, AQP1 siRNA-treated mice showed a twofold survival advantage compared to mice receiving CTRL siRNAs. The reduced AQP1-dependent tumour angiogenesis caused a hypoxic condition, evaluated by HIF-1α significant increase, in turn causing an increased level of apoptosis in AQP1 KD tumours, assessed by CASP3 quantification and DNA fragmentation. Importantly, a decreased level of MMP2 after AQP1 KD indicated a decreased activity against extracellular matrix associated with reduced vascularization and metastatic formation. In conclusion, these findings highlight an additional role for AQP1 as an important determinant of tumour dissemination by facilitating tumour cell extravasation and metastatic formation. This study adds knowledge on the role played by AQP1 in tumour biology and supports the view of AQP1 as a potential drug target for cancer therapy., (© 2017 The Authors. Journal of Cellular and Molecular Medicine published by John Wiley & Sons Ltd and Foundation for Cellular and Molecular Medicine.)

Carbonic anhydrase II (CAII) is expressed along the nephron where it interacts with a number of transport proteins augmenting their activity. Aquaporin-1 (AQP1) interacts with CAII to increase water flux through the water channel. Both CAII and aquaporin-1 are expressed in the thin descending limb (TDL); however, the physiological role of a CAII-AQP1 interaction in this nephron segment is not known. To determine if CAII was required for urinary concentration, we studied water handling in CAII-deficient mice. CAII-deficient mice demonstrate polyuria and polydipsia as well as an alkaline urine and bicarbonaturia, consistent with a type III renal tubular acidosis. Natriuresis and hypercalciuria cause polyuria, however, CAII-deficient mice did not have increased urinary sodium nor calcium excretion. Further examination revealed dilute urine in the CAII-deficient mice. Urinary concentration remained reduced in CAII-deficient mice relative to wild-type animals even after water deprivation. The renal expression and localization by light microscopy of NKCC2 and aquaporin-2 was not altered. However, CAII-deficient mice had increased renal AQP1 expression. CAII associates with and increases water flux through aquaporin-1. Water flux through aquaporin-1 in the TDL of the loop of Henle is essential to the concentration of urine, as this is required to generate a concentrated medullary interstitium. We therefore measured cortical and medullary interstitial concentration in wild-type and CAII-deficient mice. Mice lacking CAII had equivalent cortical interstitial osmolarity to wild-type mice: however, they had reduced medullary interstitial osmolarity. We propose therefore that reduced water flux through aquaporin-1 in the TDL in the absence of CAII prevents the generation of a maximally concentrated medullary interstitium. This, in turn, limits urinary concentration in CAII deficient mice.

Background and Aim: Recent studies of several carcinomas have reported that aquaporin possesses novel oncogenic properties. The aim of this study was to clarify the involvement of aquaporin-1 and -5 in the proliferation, invasion and metastasis of soft tissue sarcomas., Materials and Methods: The expression of aquaporin-1 and -5 was immunohistochemically examined in 73 soft tissue sarcomas as well as in benign, locally aggressive soft tissue tumors, and in soft tissues of adult humans and human fetuses. The mRNA and protein expression of aquaporin-1 and -5 genes were quantified in 19 sarcoma tissues., Results: Aquaporin-1 was expressed in the tumor cells of 37 (51%) and aquaporin-5 in 29 (40%) of 73 soft tissue sarcomas. Two expression patterns were identified: a differentiation-dependent pattern, similar to their expression in adult human soft tissue and in benign soft tissue tumors, and an aggressiveness-related pattern, that is similar to their expression in the mesenchymal cells of the developing fetal limb. The latter expression pattern proved to be an independent prognostic factor for patients with soft tissue sarcoma, in which aquaporin-1 was related to the invasiveness, and aquaporin-5 to the proliferation of soft tissue sarcoma cells., Conclusion: These results indicate pivotal roles for aquaporin-1 and -5 in the aggressive growth and metastatic potential of soft tissue sarcomas, suggesting that they are promising targets for the treatment of patients with intractable soft tissue sarcoma., (Copyright © 2017 The Authors. Published by Elsevier GmbH.. All rights reserved.)

Lipopolysaccharides (LPS) are known to cause cholestasis in sepsis. There is evidence that a defective expression of canalicular aquaporin water channels contributes to bile secretory failure in LPS-induced cholestasis. Thus, we studied whether the hepatic adenovirus-mediated transfer of human aquaporin-1 gene (haqp1) can improve the cholestasis induced by LPS. Adenoviral vector encoding hAQP1 (AdhAQP1) or control vector was administered to rats by retrograde intrabiliary infusion. Hepatocyte canalicular hAQP1 expression was assessed by liver immunostaining and immunoblotting in purified plasma membranes. LPS reduced bile flow and biliary bile acid excretion by 30% and 45%, respectively. AdhAQP1-treatment normalized both bile flow and biliary bile acid excretion in LPS-induced cholestasis. Moreover, markedly elevated serum bile acid levels in cholestatic rats, were also normalized with the AdhAQP1 hepatic transduction. Bile flow and serum or biliary bile acids in normal rats were not significantly altered by AdhAQP1. AdhAQP1 delivery unaffected the downregulated protein expression of canalicular bile salt export pump (BSEP/ABCB11) in cholestasis, but improved its transport activity restoring reduced canalicular cholesterol content. Our data suggest that the adenovirus-mediated hepatocyte hAQP1 expression improves LPS-induced cholestasis in rats by stimulating the BSEP/ABCB11-mediated biliary bile acid excretion; a finding that might contribute to the understanding and treatment of sepsis-associated cholestatic diseases. © 2017 IUBMB Life, 69(12):978-984, 2017., (© 2017 International Union of Biochemistry and Molecular Biology.)

The present study aimed to evaluate the effects of aquaporin-1 (AQP1) level and intratumoral microvessel density (IMD) on the clinicopathological features of patients with hepatocellular carcinoma (HCC). The AQP1 expression levels, IMD and AQP1/IMD ratios in patients with HCC were measured using a semi-quantitative immunohistochemical technique. The association between these features and clinicopathological variables were evaluated. The prognostic impact of AQP1 and IMD on overall survival (OS), and 5-year disease-free survival (DFS) of HCC patients was investigated retrospectively. P<0.05 was considered to indicate a statistically significant difference. A total of 90 cases of HCC were included in the present study. AQP1 was markedly expressed in the membranes of microvessels and small vessels, but seldom in hepatocellular carcinoma cells. Blood vessels in the tumors were markedly stained by anti-cluster of differentiation 34 antibody. AQP1 expression and IMD was significantly correlated with tumor size, histologic grade, Child-Pugh classification, microvascular invasion and tumor-node-metastasis (TNM) stage (P<0.05). Concurrently, for the 5-year DFS and OS, a larger tumor size, poorly differentiated histological grade, B and C Child-Pugh classification, presence of microvascular invasion, high TNM stage, a high AQP1 expression and a high IMD were significant risk factors for mortality. Multivariate analysis revealed that TNM stage and IMD were independent unfavorable prognostic markers for 5-year DFS (P=0.049 and P=0.025, respectively) and OS (P=0.043 and P=0.042, respectively). These data suggest that high AQP1 expression and IMD are associated with tumor progression and prognosis in HCC. The IMD level may serve as an independent indicator for the 5-year DFS and OS.