The Effect of Shen Qi Wan Medicated Serum on NRK-52E Cells Proliferation and Migration by Targeting Aquaporin 1 (AQP1)

BACKGROUND Shen Qi Wan (SQW) as a well-known formula for the amelioration of kidney yang deficiency syndrome (KYDS), and it has been widely employed in traditional Chinese medicine (TCM). This study aimed to investigate the effect and underlying mechanism of SQW medicated serum on proliferation and migration in NRK-52E cells. MATERIAL AND METHODS We employed the real-time cell analysis (RTCA) system to investigate the effect of SQW medicated serum on proliferation and migration in NRK-52E cells. In addition, the migration was further investigated by using a wound-healing assay. The mRNA and protein expression level of aquaporin 1 (AQP1) of NRK-52E cells with SQW medicated serum-treated were quantified by real-time quantitative polymerase chain reaction (q-PCR) and western blot assay, respectively. Furthermore, NRK-52E cells were transfected with lentivirus AQP1-RNAi to assess migratory cell abilities in vitro. RESULTS The migratory abilities of NRK-52E cells were significantly increased after SQW medicated serum treatment (P<0.05), and no significant difference in cell proliferation. In addition, SQW medicated serum was significantly upregulated the mRNA and protein expression level of AQP1 in NRK-52E cells (P<0.05). Additionally, the in vitro metastasis test proved that knockdown of AQP1 suppressed migratory abilities according to RTCA and wound healing test while was reversed by SQW medicated serum (P<0.05). CONCLUSIONS Our study demonstrates that SQW medicated serum effectively promotes the migration of NRK-52E cells by increasing AQP1 expression, and AQP1 may be as a therapeutic target of SQW for renal injury treatment under KYDS.

Aldosterone Contributed to Pulmonary Arterial Hypertension Development via Stimulating Aquaporin Expression and Pulmonary Arterial Smooth Muscle Cells Proliferation

INTRODUCTION AND OBJECTIVE

The regulatory network of aquaporin (AQP) 1 and renin-angiotensin-aldosterone (ALDO) system are not quite clear in pulmonary arterial hypertension (PAH). Thus, we explored the role of AQP1, ALDO and spirolactone (SP) in the PAH animal model and pulmonary arterial smooth muscle cells (PASMCs).

METHOD

PAH rat model was established by monocrotaline (MCT) via intraperitoneal in SD rat. Hemodynamic measurement was conducted via the external jugular vein cannula. PASMCs were extracted from normal SD rat and cultured in SmGM medium. α-Actin expression was identified by immunocytochemistry. Protein levels were assessed by Western blot. Cell viability was assayed using the MTT method. Apoptosis rate was evaluated by flow cytometry. ALDO level was measured by ELISA.

RESULT

SP decreased AQP1 and β-catenin expressions in PAH rat model induced successfully by MCT. Moreover, ALDO increased AQP1 expression and cell viability in PASMCs, which were extracted from rat and identified by α-actin expression. AQP1 downregulation decreased β-catenin expression, and SP lowered AQP1 and β-catenin expressions elevated by ALDO in PASMCs. SP offset ALDO's effect on the upregulation of cell viability as well as AQP1 and β-catenin expressions in PASMCs. In addition, AQP1 downregulation and SP have a negative effect on Ki-67 and proliferating cell nuclear antigen expressions as well as cell viability after ALDO treatment in PASMCs.

CONCLUSION

ALDO might contribute to PAH development via stimulating AQP1 expression and PASMCs proliferation. However, SP could be considered an effective drug regulating PASMCs proliferation through modulating AQP1 and β-catenin expressions in PAH.

Expression patterns of aquaporins 1 and 4 in stroke

Ischemic stroke occurs through embolic or thrombotic obliteration of an artery from cerebral circulation and represents over 80% of all stroke cases. One of the fiercest complications after stroke is edema, which results from imbalanced water diffusion around the blood vessels walls. Water diffusion around blood vessel walls occurs physiologically mainly through two protein-formed pores, namely aquaporins (AQPs) 1 and 4. Here, we compare for the first time the expression patterns and colocalization degrees of the two AQPs in control brain tissue and in peri-ischemic regions, on tissue obtained from eight patients with confirmed ischemic pathology and from five control cases. Our analysis showed that AQP4 is more abundant that AQP1, especially in the cortex and in the organized scar areas. The colocalization of the two markers was high, both located on the astrocytes membranes, but the colocalization degree decreased in the scar peri-ischemic regions. Colocalization with basement membranes was also lower for AQP1 compared to AQP4, in all regions analyzed.

Pistacia integerrima ameliorates airway inflammation by attenuation of TNF-α, IL-4, and IL-5 expression levels, and pulmonary edema by elevation of AQP1 and AQP5 expression levels in mouse model of ovalbumin-induced allergic asthma

BACKGROUND

Natural products are considered as an essential source for the search of new drugs. Pistacia integerrima galls (PI) have been used for the treatment of asthma and cough in traditional system of medicine.

AIM/HYPOTHESIS

Current study investigates the immunomodulatory and anti-inflammatory activities of P. integerrima in mouse model of ovalbumin-induced allergic asthma.

METHODS

Mice were intraperitoneally sensitized and subsequently challenged intranasally with ovalbumin to induce allergic asthma. Experimental group mice were treated with methanol extract of P. integerrima extract (200mg/kg b. w.) and Methylprednisolone (MP) (15mg/kg b. w.) for 07 consecutive days, alongside intranasal challenge. Lung tissues were stained with Hematoxyline and Eosin (H & E), and Periodic Acid-Schiff (PAS) stains for histopathological evaluation. Lung wet/dry weight ratio was measured as an index of lung tissue edema. Albumin was injected in the right ear 24h before sacrificing the mice and difference of weight was taken as a degree of delayed type hypersensitivity (DTH). mRNA expression levels of TNF-α, IL-4, IL-5, Aquaporin-1 (AQP1), and AQP5 were evaluated using reverse transcription polymerase chain reaction (RT-PCR) followed by gel electrophoresis.

RESULTS

The data showed both PI extract and MP significantly alleviated DTH and nearly normalized total leukocyte count and differential leukocyte count in both blood and BALF. We found significantly suppressed goblet cell hyperplasia and inflammatory cell infiltration after treatment with both PI extract and MP. Expression levels of TNF-α, IL-4, and IL-5 were also found significantly reduced after treatment with both PI extract and MP, which might have resulted in the amelioration of airway inflammation. Current study displayed that both PI extract and MP significantly decreased lung wet/dry ratio, suggesting reduction in pulmonary edema. RT-PCR analysis showed significant increase in AQP1 and AQP5 expression levels after treatment with both PI extract and MP, which might have caused the alleviation of pulmonary edema.

CONCLUSION

Our study displays that P. integerrima possesses significant anti-asthmatic activity which may be attributed to reduction in TNF-α, IL-4, and IL-5 expression levels, and increase in AQP1 and AQP5 expression levels.

Aquaporin 1 protein expression is associated with BRAF V600 mutation and adverse prognosis in cutaneous melanoma

Despite experimental findings suggesting the prognostic significance of Aquaporin 1 (AQP1) in human melanoma, no published clinical data are available. We studied the expression of AQP1 protein in cutaneous melanoma, correlated our findings with standard histological and genetic markers, and long-term clinical follow-up. Our study evaluated the AQP1 protein expression in 78 melanoma patients, representing two predefined risk cohorts using the immune labeling technique with commercially available anti-AQP1 antibodies on routinely formalin-fixed and paraffin-embedded tumor tissue samples. BRAF V600E mutation analyses were carried out successfully in 70 patients using PCR and restriction fragment length polymorphism analyses, followed by confirmatory analysis with the Sanger sequencing technique. AQP1-expressing melanoma cells were found in 52 cases (66.7%, median H-score=124.24). Significantly higher AQP1 H-scores (P=0.047) were found in the 'high-risk' patients. No correlations were found with the established histological markers, such as mitotic index (P=0.42), Clark level (P=0.95), and Breslow thickness (P=0.51). BRAF V600 mutation analyses were successful in 89%, and showed a two times higher mutation frequency in the 'high-risk' group. The BRAF V600 mutations were significantly associated with AQP1 expression (P=0.014). Long-term follow-up indicated a reduced progression-free survival (P=0.036) and overall survival (P=0.017) for the AQP1-positive cutaneous melanoma patients. AQP1 expression is likely to be associated with an adverse prognosis in cutaneous melanoma.

Decreased Expression of Aquaporin-1 in Lung Tissue of Silicotic Rats

BACKGROUND

Aquaporin-1 (AQP-1), found in the early 1990s, a water channel protein in the cell membranes of mammals, has been reported to play an important role in water balance of the respiratory system. However, there are a few studies about the role of AQP in occupational pulmonary disease such as silicosis. This study is to explore the information of aquaporin-1 (AQP-1) in the pathogenesis of silicosis by examining AQP expression, distribution, and location in the lung tissue of a silicotic rat model.

METHODS

Male Wistar SPF rats were divided randomly into the following 8 groups (n = 8 per group): (1) saline control group: instillation of 1 mL sterile physiological saline; (2) silica groups (ld, 7d, 14d, 28d, 42d, 56d): instillation of a suspension of 50 mg silica dust in a total volume of 1 mL sterile physiological saline; (3) the normal control group without treatment. Immunohistochemistry, immunofluorescence, and western blot were used to detect distribution and expression of AQP-1 in the lung tissue of rats exposed to silica.

RESULTS

The expression of AQP-1 between normal and the saline control rats showed no significant difference, but was decreased in the silicotic model rats' lung.

CONCLUSIONS

The expression of AQP-1 decreased in silicotic rats, which suggests that AQP-1 may play an important role in the formation of silicosis.

Water Channels Aquaporin 4 and -1 Expression in Subependymoma Depends on the Localization of the Tumors

BACKGROUND

We analyzed aquaporin 4 and -1 expression in subependymomas, benign and slow growing brain tumors WHO grade I. Ten subependymoma cases were investigated, five of the fossa inferior and five of the fossa superior.

METHODS AND RESULTS

Using immunohistochemistry, we observed different aquaporin expression patterns depending on localization: aquaporin 4 and -1 were detected in infratentorial subependymomas in the entire tumor tissue. In contrast, supratentorial subependymomas revealed aquaporin 4 and -1 expression only in border areas of the tumor. PCR analyses however showed no difference in aquaporin 4 expression between all subependymomas independent of localization but at higher levels than in normal brain. In contrast, aquaporin 1 RNA levels were found to be higher only in infratentorial samples compared to supratentorial and normal brain samples. The reason for the different distribution pattern of aquaporin 4 in subependymomas still remains unclear. On the cellular level, aquaporin 4 was redistributed on the surface of the tumor cells, and in freeze fracture replicas no orthogonal arrays of particles were found. This was similar to our previous findings in malignant glioblastomas. From these studies, we know that extracellular matrix molecules within the tumor like agrin and its receptor alpha-dystroglycan are involved in forming orthogonal arrays of particles. In subependymomas neither agrin nor alpha-dystroglycan were detected around blood vessels.

CONCLUSIONS

Taken together, we show in this study that in the benign subependymomas aquaporins 1 and 4 are dramatically redistributed and upregulated. We speculate that extracellular environments of infra- and supratentorial subependymomas are different and lead to different distribution patterns of aquaporin 4 and -1.

Reciprocity in the developmental regulation of aquaporins 1, 3 and 5 during pregnancy and lactation in the rat

Milk secretion involves significant flux of water, driven largely by synthesis of lactose within the Golgi apparatus. It has not been determined whether this flux is simply a passive consequence of the osmotic potential between cytosol and Golgi, or whether it involves regulated flow. Aquaporins (AQPs) are membrane water channels that regulate water flux. AQP1, AQP3 and AQP5 have previously been detected in mammary tissue, but evidence of developmental regulation (altered expression according to the developmental and physiological state of the mammary gland) is lacking and their cellular/subcellular location is not well understood. In this paper we present evidence of developmental regulation of all three of these AQPs. Further, there was evidence of reciprocity since expression of the rather abundant AQP3 and less abundant AQP1 increased significantly from pregnancy into lactation, whereas expression of the least abundant AQP5 decreased. It would be tempting to suggest that AQP3 and AQP1 are involved in the secretion of water into milk. Paradoxically, however, it was AQP5 that demonstrated most evidence of expression located at the apical (secretory) membrane. The possibility is discussed that AQP5 is synthesized during pregnancy as a stable protein that functions to regulate water secretion during lactation. AQP3 was identified primarily at the basal and lateral membranes of the secretory cells, suggesting a possible involvement in regulated uptake of water and glycerol. AQP1 was identified primarily at the capillary and secretory cell cytoplasmic level and may again be more concerned with uptake and hence milk synthesis, rather than secretion. The fact that expression was developmentally regulated supports, but does not prove, a regulatory involvement of AQPs in water flux through the milk secretory cell.

Visceral and post-Kala-Azar dermal leishmaniasis isolates show significant difference in their in vitro drug susceptibility pattern

Visceral leishmaniasis (VL) remains a major health problem in old world, and India accounts for half of the world burden. The widespread emergence of resistance to standard drug in India poses a major obstacle in the control of leishmaniasis. Post-Kala-Azar dermal leishmaniasis (PKDL) is considered as main source of drug resistance. Experimental data indicate that resistance against newer drugs is also imminent. Therefore, in vitro studies were carried out to test minimum parasiticidal concentration of five conventional and newly introduced anti-leishmanial drugs against 20 field isolates of Leishmania donovani obtained from visceral and post-Kala-Azar dermal leishmaniasis patients of India. Study revealed wide range of variation in minimum inhibitory concentration of sodium antimony gluconate (SAG). PKDL isolates displayed significantly lower susceptibility to SAG and miltefosine than VL isolates with P value of 0.0006 and 0.0243, respectively. All clinical isolates had higher IC(50) value for paromomycin and miltefosine as compared to reference strain indicating their vulnerability to develop unresponsiveness. However, isolates were uniformly susceptible to pentamidine and amphotericin B. The results of gene expression analysis of AQP1 were largely in agreement with phenotypic drug sensitivity results. Interestingly, significant down-regulation of AQP1 was observed in PKDL isolates as compared to VL isolates indicating their increased propensity for drug unresponsiveness. However, no significant difference in mRNA expression of LdMT and LdRos3 gene was found for two groups. The present study unravels valuable baseline scientific data showing variation in the drug susceptibility pattern in the L. donovani isolates. The information might have impact on the management and control of Indian visceral leishmaniasis.

The effects of copper on Na(+)/K (+)-ATPase and aquaporin expression in two euryhaline invertebrates

We used immunocytochemical and fluorometric techniques to show that gill cells of two marine invertebrates, the crab Neohelice granulata (osmoregulator) and the clam Mesodesma mactroides (osmoconformer), increase the expression of membrane transporters [Na(+)/K(+)-ATPase and aquaporin (AQP1)] after whole-animals exposure (96 h) to sublethal concentrations of copper in water of salinity 30 ppt, when both clams and crabs are isosmotic with respect to the environmental medium. A plausible interpretation of our findings is that this increased expression in membrane transporters may serve as an attempt to ameliorate the deleterious effects of copper on the mechanisms involved in ion and volume regulation in gill cells.

Recombinant production of human Aquaporin-1 to an exceptional high membrane density in Saccharomyces cerevisiae

In the present paper we explored the capacity of yeast Saccharomyces cerevisiae as host for heterologous expression of human Aquaporin-1. Aquaporin-1 cDNA was expressed from a galactose inducible promoter situated on a plasmid with an adjustable copy number. Human Aquaporin-1 was C-terminally tagged with yeast enhanced GFP for quantification of functional expression, determination of sub-cellular localization, estimation of in vivo folding efficiency and establishment of a purification protocol. Aquaporin-1 was found to constitute 8.5 percent of total membrane protein content after expression at 15°C in a yeast host over-producing the Gal4p transcriptional activator and growth in amino acid supplemented minimal medium. In-gel fluorescence combined with western blotting showed that low accumulation of correctly folded recombinant Aquaporin-1 at 30°C was due to in vivo mal-folding. Reduction of the expression temperature to 15°C almost completely prevented Aquaporin-1 mal-folding. Bioimaging of live yeast cells revealed that recombinant Aquaporin-1 accumulated in the yeast plasma membrane. A detergent screen for solubilization revealed that CYMAL-5 was superior in solubilizing recombinant Aquaporin-1 and generated a monodisperse protein preparation. A single Ni-affinity chromatography step was used to obtain almost pure Aquaporin-1. Recombinant Aquaporin-1 produced in S. cerevisiae was not N-glycosylated in contrast to the protein found in human erythrocytes.

Correlation of aquaporin-1 water channel protein expression with tumor angiogenesis in human astrocytoma

Aquaporin-1 (AQP1) is a water channel protein, widely expressed in epithelial and endothelial cells, known to be associated with invasion, angiogenesis, cell migration and formation of tumour oedema in several malignancies. We investigated the pattern of immunohistochemical expression of AQP1 in human astrocytomas and its role in tumour angiogenesis and infiltration. Immunohistochemical staining of AQP1 was performed in astrocytomas of grade II, III and IV. Intensity and pattern of expression were analysed. Non-neoplastic brain tissues served as control. There was a significant increase in the intensity of AQP1 expression from low-grade to high-grade astrocytomas (p<0.0001). Despite intense expression of AQP1 in astrocytoma grade IV, we observed strong regional differences. AQP1 up-regulation was predominantly located perivascularly, in areas of tumour infiltration, distant from the necrotic tumour core. AQP1 expression correlates with the grade of malignancy and is associated with angiogenesis, as well as with invasion of grade IV tumour in areas of tumour infiltration. Suppression of AQP1 expression could be a potential means of reducing invasion of glioma cells.

Early alteration of urinary exosomal aquaporin 1 and transforming growth factor β1 after release of unilateral pelviureteral junction obstruction

BACKGROUND/PURPOSE

Down-regulation of aquaporin 1 (AQP1) and up-regulation of transforming growth factor β(1) (TGF-β(1)) in the renal parenchyma have been demonstrated in children who underwent pyeloplasty for pelviureteral junction obstruction. However, no information about urinary exosomal AQP1 and TGF-β(1) during postobstructive polyuria in children with congenital unilateral hydronephrosis is available. The aim of the present study is to evaluate the urine concentration of exosomal AQP1 and TGF-β(1) on the first and the second day after surgery in children who underwent pyeloplasty.

METHODS

Twenty-two patients (age, 36.2 ± 17.1 months) with unilateral pelviureteral junction obstruction were examined in the study. For the first 2 days after the operation, the urine was collected separately from pyelostomy draining only from the postobstructed kidney and from the bladder catheter draining mostly from the contralateral kidney, which was used as an internal control. Urinary output, urinary osmolality, sodium, β(2)-microglobulin (β(2)-MG), and creatinine, as well as urinary exosomal AQP1 and TGF-β(1) excretion, were tested in each sample.

RESULTS

After pyeloplasty, a significantly decreased urinary excretion of exosomal AQP1 (≈ 64%) was found in the postobstructed kidney. The patients developed polyuria (807 ± 216 mL/24 h vs 484 ± 144 mL/24 h at day 1, 1021 ± 348 mL/24 h vs 603 ± 228 mL/24 h at day 2; P < .01) and reduced urine osmolality (115 ± 44 mOsm/kg vs 282 ± 61 mOsm/kg at day 1, 139 ± 39 vs 303 ± 46 mOsm/kg at day 2; P < .01) that persisted for 48 hours. In parallel, urinary TGF-β(1) and β(2)-MG (normalized for creatinine) from the postobstructed kidney were significantly higher compared with the contralateral kidney. The urine output and urinary sodium concentration from the postobstructed kidney elevated significantly on the second day after the release of obstruction compared with those on the first day. The contralateral kidney also showed same trends.

CONCLUSIONS

The down-regulation of urinary exosomal AQP1 in the postobstructed kidney may account for the polyuria, hypotonic urine, and elevated urinary β(2)-MG. The urinary TGF-β(1) level locally increased in the postobstructed kidney may be involved in renal AQP1 down-regulation.

Aquaporin-1: a potential membrane channel for facilitating the adaptability of rabbit nucleus pulposus cells to an extracellular matrix environment

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.

Expression of aquaporin-1 in nasopharyngeal cancer tissues

OBJECTIVE

To investigate the expression of aquaporin-1 (AQP1) in nasopharyngeal tumour and nontumour tissues.

METHOD

Thirty nasopharyngeal biopsy samples were collected and examined with both immunohistochemistry and real-time fluorescence quantitative polymerase chain reaction (RT-PCR) to detect the expression level of AQP1 in tissues.

RESULTS

Immunohistochemistry data suggested that AQP1 was expressed in both nasopharyngeal tumour and normal tissues, but tumour tissues were stained a lot stronger than nontumour tissues. RT-PCR analysis further confirmed the overexpression of AQP1 in tumour tissues; migrated tumour tissue had even higher expression.

CONCLUSION

The expression level of aquaporin-1 in nasopharyngeal cancer tissue could be involved in tumour migration.

Assessing aquaglyceroporin gene status and expression profile in antimony-susceptible and -resistant clinical isolates of Leishmania donovani from India

OBJECTIVES

Clinical resistance to pentavalent antimonials results from an interplay between uptake, efflux and sequestration in Leishmania. Aquaglyceroporins (AQPs) have been shown to facilitate uptake of trivalent metalloids. Down-regulation of AQP1 in Leishmania results in resistance to trivalent antimony, whereas overexpression of AQP1 in drug-resistant parasites can reverse the resistance. The present work investigates the role of AQP1 in monitoring antimonial resistance in Indian leishmaniasis.

METHODS AND RESULTS

Susceptibility to trivalent antimony as determined in vitro with intracellular amastigotes from both visceral leishmaniasis (VL) and post-kala-azar dermal leishmaniasis (PKDL) patients correlated well with the clinical response. Higher accumulation of trivalent antimony (SbIII) was observed in all susceptible isolates compared with resistant isolates. Reduced accumulation of SbIII correlated, with a few exceptions, with down-regulation of AQP1 RNA as determined by real-time PCR. Cloning and sequencing of the AQP1 gene from both VL and PKDL isolates showed sequence variation in four of the clinical isolates. None of the isolates had an alteration of Glu152 and Arg230, which have been previously shown to affect metalloid transport. Transfection of the AQP1 gene in a sodium antimony gluconate-resistant field isolate conferred susceptibility to the resistant isolate.

CONCLUSIONS

Our studies indicate genetic variation in VL and PKDL isolates. Down-regulation of AQP1 correlates well with clinical drug resistance in a majority of Indian VL and PKDL isolates. AQP1 gene expression at both the genetic and transcriptional level showed positive correlation with SbIII accumulation, with some exceptions.

Correlation between the expression of aquaporin 1 and hypoxia-inducible factor 1 in breast cancer tissues

The correlation between aquaporin 1 (AQP1) and hypoxia-inducible factor 1 (HIF 1) in breast cancer tissues was preliminarily studied. In 155 cases of breast cancer, the expression levels of AQP1 were detected by immunohistochemistry in HIF1-positive group or HIF1-negative group, and the correlation between AQP1 and HIF1 was analyzed. The overexpression of AQP1 and HIF1 were observed in 155 cases of breast cancer tissues. The expression level of AQP1 in HIF1-positive group was significantly higher than that in HIF1-negative group. The positive expression rate of AQP1 was 296.55+/-24.67 and 168.37+/-37.53 in HIF1-positive group and HIF1-negative group respectively with the difference being very significant between them (P<0.001). It was concluded that AQP1 was overexpressed in the HIF1-positive group and there were some correlations between AQP1 and HIF1, suggesting they interact each other and regulate the oncogenesis of breast cancer.

[Expression of aquaporin 1 in human placenta and fetal membranes]

OBJECTIVE

To detect aquaporin1 (AQP1) expression in normal human placenta and fetal membranes.

METHODS

Human placenta and fetal membrane specimens were collected from 5 pregnant women with intact membranes undergoing elective cesarean sections at term. Expression and localization of AQP1 was detected by RT-PCR, Western blotting and immunohistochemistry.

RESULTS

AQP1 mRNA was detected in the placenta and fetal membranes by RT-PCR, and Western blotting also yielded positive results for the specimens, showing a specific band around 28 kD. Immunohistochemical staining showed AQP1 expression in the vascular endothelial cells and syncytiotrophoblasts of the placenta, epithelial cells of the amnion, and cytotrophoblasts of the chorion.

CONCLUSION

The presence of AQP1 expression in the placenta and fetal membranes suggest that AQP1 may play an important role in maternal-fetal fluid exchange and amniotic fluid balance.

[Correlation of aquaporin 1 with hypoxia-inducible factor 1 in breast cancer]

OBJECTIVE

To determinate the correlation of aquaporin 1 (AQP1) and hypoxia-inducible 1 (HIF-1).

METHODS

155 samples of breast cancer obtained during radical mastectomy underwent immunohistochemistry to detect the expression of AQP1 and HIF-1.

RESULTS

The positive rates of AQP1 in the HIF1 positive group was 297 +/- 25, significantly higher than that of HIF1 negative group (168 +/- 38, P < 0.001).

CONCLUSION

AQP1 is positively correlated with HIF1. The interaction of AQP1 and HIF1 may co-regulate the progress of breast cancer.

Regulation and function of aquaporin-1 in glioma cells

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.

Exceptional overproduction of a functional human membrane protein

Eukaryotic--especially human--membrane protein overproduction remains a major challenge in biochemistry. Heterologously overproduced and purified proteins provide a starting point for further biochemical, biophysical and structural studies, and the lack of sufficient quantities of functional membrane proteins is frequently a bottleneck hindering this. Here, we report exceptionally high production levels of a correctly folded and crystallisable recombinant human integral membrane protein in its active form; human aquaporin 1 (hAQP1) has been heterologously produced in the membranes of the methylotrophic yeast Pichia pastoris. After solubilisation and a two step purification procedure, at least 90 mg hAQP1 per liter of culture is obtained. Water channel activity of this purified hAQP1 was verified by reconstitution into proteoliposomes and performing stopped-flow vesicle shrinkage measurements. Mass spectrometry confirmed the identity of hAQP1 in crude membrane preparations, and also from purified protein reconstituted into proteoliposomes. Furthermore, crystallisation screens yielded diffraction quality crystals of untagged recombinant hAQP1. This study illustrates the power of the yeast P. pastoris as a host to produce exceptionally high yields of a functionally active, human integral membrane protein for subsequent functional and structural characterization.

[Effect of hypertonic medium on expression of aquaporin-1 in pleural mesothelial cells: experiment with rats]

OBJECTIVE

To study the expression of aquaporin-1 (AQP-1) in pleural mesothelial cells (PMCs) and the influence of hypertonic medium thereupon.

METHODS

Rat PMCs were isolated, cultured, and divided into 2 groups: hypertonic group, cultured in hypertonic media with NaCl of different concentrations for 24 h and control group, cultured in D-MEM/F-12 medium. The 100 mmol/L NaCI group was examined at the time points 6, 12, 18, and 24 h respectively. RT-PCR and Western blotting were used to analyze the mRNA and protein expression of AQP-1.

RESULTS

The A values of AQP-1 protein expression were 24.0 +/- 1.8, 27.8 +/- 2.4, 31.7 +/- 2.5, 89.7 +/- 6.2, and 107.7 +/- 9.3 respectively in the PMCs treated with hypertonic media with NaCl of the concentrations of 25, 50, 75, 100, and 150 mmol/L, all significantly higher than that in the control group (10.8 +/- 1.5, all P < 0.01). The A values of AQP-1 protein expression were 42.1 +/- 2.6, 78.9 +/- 3.6, 109.6 +/- 7.6, and 123.4 +/- 8.7 in the PMCs treated with hypertonic media with NaCl of the concentration of 100 mmol/L after 6 h, 12 h, 18 h, and 24 h, all significantly higher than that in the control group (12.9 +/- 1.9, P < 0. 01). The a values of AQP-1 mRNA expression were 62.6 +/- 6.4, 75.3 +/- 5.5, 122.3 +/- 11.4, 196.2 +/- 18.1, and 223.0 +/- 19.3 respectively in the PMCs treated with hypertonic media with NaCl of the concentrations of 25, 50, 75, 100, and 150 mmol/L, all significantly higher than that in the control group (23.5 +/- 2.7, all P < 0.01). The A values of AQP-1 protein expression were 83.6 +/- 6.1, 159.3 +/- 6.9, 266.2 +/- 24.1, and 196.2 +/- 15.7 in the PMCs treated with hypertonic media with NaCl of the concentration of 100 mmol/L after 6 h, 12 h, 18 h, and 24 h, all significantly higher than that in the control group (26.5 +/- 2.8, P < 0.01).

CONCLUSION

Hypertonic medium increases the expression of AQP-1 mRNA and protein. AQP-1 participates in the pleural fluid formation.

Increased expression of aquaporin-1 on the pleura of rats with a tuberculous pleural effusion

OBJECTIVE

The purpose of this study was to investigate whether the expression of AQP-1 on the pleura is altered in a rat model with a tuberculous pleural effusion (TPE) and to study its function.

METHODS

A TPE model was established by intrapleural inoculation with 0.03 mg (2 ml) standard tuberculosis bacillus (H(37)Rv). The rats with TPE were sacrificed at different time points (day 1, 3, or 5) after inoculation. The control group received a 2-ml intrapleural injection of saline. The visceral and parietal pleural tissues were harvested and processed for real-time RT-PCR, Western blot, immunohistochemistry, and determination of tissue AQP-1 levels. Recombinant adenovirus Ad-rAQP-1 containing full-length cDNA of AQP-1 was constructed. Six groups of seven Wistar rats were assigned to receive the following treatments: group 1: intrapleural administration of normal saline; group 2: intrapleural administration of tuberculosis bacilli (TB); group 3: intrapleural inoculation with TB at day 7 following intrapleural administration of Ad-rAQP-1 vector; group 4: intrapleural inoculation with 0.03 mg TB at day 7 following intrapleural administration of control Ad-GFP vector; group 5: intrapleural administration of Ad-rAQP-1; group 6: intrapleural administration of control Ad-GFP vector. The expression of AQP-l on the pleural tissue was detected by immunohistochemistry and Western blot analysis. Histopathologic changes of the pleura and the volume of pleural fluid were examined on day 7 following gene intervention or on day 3 following TB inoculation.

RESULTS

Bilateral pleural effusions appeared within 5 days in all rats who received an intrapleural inoculation with TB. The peak amount of pleural fluid occurred on day 3. The AQP-1 expression at protein and mRNA was increased in the early phase of TPE. The expression of AQP-1 was increased in the Ad-rAQP-1 gene transfer group, indicating successful adenovirus gene transfer. The volume of pleural fluid in group 3 (6.1 +/- 0.7 ml) was significantly increased compared with that in group 2 (3.8 +/- 1.0 ml) and group 4 (4.0 +/- 1.1 ml).

CONCLUSION

These findings suggested that AQP-1 was increased in TPE and it may be involved in the formation of TPE.

Down-regulation of aquaporin-1 in intrahepatic cholangiocarcinoma is related to tumor progression and mucin expression

Aquaporin-1 (AQP-1) has been found to be important in bile formation across cell membranes of the biliary epithelium, and thus it has been suggested that AQP-1 is involved in the pathogenesis of hepatobiliary disease. To clarify the role of AQP-1 in the development of intrahepatic cholangiocarcinoma, we determined AQP-1 expression in the normal bile duct, 21 cases of biliary dysplasia, and in 112 cases of intrahepatic cholangiocarcinoma by immunohistochemical analysis. Mucus core protein 5AC expression, a poor prognostic marker of intrahepatic cholangiocarcinoma, was also assessed in intrahepatic cholangiocarcinoma cases. High (>50%) expression of AQP-1 was detected in 16% (9/58) of the normal large bile ducts examined, and in 48% (10/21) of the biliary dysplasia samples originating from large bile ducts. High (>50%), low (<or=50%), and negative AQP-1 expression was observed in 46 (41%), 20 (19%), and 46 (41%) cases of intrahepatic cholangiocarcinoma, respectively. Large tumor size (>40 mm) and poorly differentiated histology were significantly more prevalent in the negative AQP-1 group than in the high AQP-1 group. Low or negative AQP-1 expression was associated with positive lymph node metastasis (P=.0001). AQP-1 expression was found to inversely correlate with that of mucus core protein 5AC, and their distributions tended to be complementary. The low and negative AQP-1 expression was an independent prognostic factor by multivariate survival analysis. We concluded that AQP-1 is up-regulated in biliary dysplasia, as compared with in the normal large bile duct, and down-regulation of AQP-1 is associated with mucin production and aggressive progression of intrahepatic cholangiocarcinoma.

[Expression profile of aquaporin 1 in patients with menorrhagia]

OBJECTIVE

To investigate the expression of aquaporin 1 (AQP1) in endometrium of patients with menorrhagia.

METHODS

RT-PCR and immunohistochemistry were carried out in twenty women with normal menstrual cycle to confirm the expression of AQP1 in endometrium and locate it. Then 51 women with menorrhagia and 40 women with normal menstrual cycle were included in the study. RT-PCR and immunohistochemistry were used to examine the expression of AQP1.

RESULT

AQP1 mRNA was expressed in the human endometrium throughout menstruation cycle, which was mainly located in the endothelia of the capillaries and small blood vessels. Quantification of the immunostaining revealed higher density during secretary phase than that in proliferative phase (P<0.01). The staining intensity and density of AQP1-positive microvessel decreased significantly in simple hyperplasia group (P<0.01) and then gradually increased in complex hyperplasia and atypical hyperplasia groups (P<0.001).

CONCLUSION

Decreased expression of AQP1 may lead to disturbed endometrial vascular remodeling and may be involved in the occurrence of menorrhagia.

Development of cytosolic hypoxia and hypoxia-inducible factor stabilization are facilitated by aquaporin-1 expression

O(2) is essential for aerobic life, and the classic view is that it diffuses freely across the plasma membrane. However, measurements of O(2) permeability of lipid bilayers have indicated that it is much lower than previously thought, and therefore, the existence of membrane O(2) channels has been suggested. We hypothesized that, besides its role as a water channel, aquaporin-1 (AQP-1) could also work as an O(2) transporter, because this transmembrane protein appears to be CO(2)-permeable and is highly expressed in cells with rapid O(2) turnover (erythrocytes and microvessel endothelium). Here we show that in mammalian cells overexpressing AQP-1 and exposed to hypoxia, the loss of cytosolic O(2), as well as stabilization of the O(2)-dependent hypoxia-inducible transcription factor and expression of its target genes, is accelerated. In normoxic endothelial cells, knocking down AQP-1 produces induction of hypoxia-inducible genes. Moreover, lung AQP-1 is markedly up-regulated in animals exposed to hypoxia. These data suggest that AQP-1 has O(2) permeability and thus could facilitate O(2) diffusion across the cell membrane.

Human astrocytes express aquaporin-1 and aquaporin-4 in vitro and in vivo

Aquaporins (AQP) constitute an evolutionarily conserved family of integral membrane water transport channel proteins. Previous studies indicate that AQP1 is expressed exclusively in the choroid plexus epithelium, while AQP4 is localized on the vascular foot of astrocytes in the central nervous system (CNS) under physiological conditions. To investigate a role of AQP in the pathophysiology of neurological diseases involving astrogliosis we studied the expression of AQP1 and AQP4 in cultured human astrocytes and brain tissues of multiple sclerosis (MS), cerebral infarction and control cases. By reverse transcriptasepolymerase chain reaction and western blot analysis, cultured human astrocytes co-expressed both AQP1 and AQP4 mRNA and proteins, where AQP4 levels were elevated by exposure to interferon-gamma but neither by tumor necrosis factor-alpha nor interleukin-1beta, whereas AQP1 levels were unaffected by any of the cytokines examined. By western blot analysis, AQP1 and AQP4 proteins were detected in the brain homogenates of the MS and non-MS cases, where both levels were correlated with those of glial fibrillary acid protein. By immunohistochemistry, astrocytes with highly branched processes surrounding blood vessels, along with glial scar, expressed intensely AQP1 and AQP4 in MS and ischemic brain lesions, whereas neither macrophages, neurons nor oligodendrocyte cell bodies were immunopositive. These immunohistochemical results indicate that the expression not only of AQP4 but also of AQP1 was enhanced in MS and ischemic brain lesions located predominantly in astrocytes, suggesting a pivotal role of astrocytic AQP in the maintenance of water homeostasis in the CNS under pathological conditions.

[Protection effect of Salvia miltiorrhiza on model of acute lung injury in rats]

OBJECTIVE

To investigate the effect of SM on aquaporin-1 (AQP1) expression in rats with acute lung injury (ALI), and study protection against ALI.

METHODS

48 SD rats were randomly divided into normal group, ALI 7-day group, ALI 8-hour group, SM prevention group, SM 7-day treatment group, and SM 8-hour treatment group. At 8 hours and 7 days after treatment, lung wet-to-dry weight ratio, lung pathology, electron microscope, AQP1 immunohistochemistry, and AQP1 Western blot were performed.

RESULTS

The model group rats all appeared ALI symptom. Compared with the 7-day ALI group, the degree of lung edema statement alleviated in SM 7-day treatment group. But the expression of AQP-1 was not significant between the two groups (P < 0.05). Compared with the 8-hour ALI group, the degree of lung edema statement alleviated in SM 8-hour treatment group and SM prevention group. The expression of AQP-1 was significantly expression in the group of SM prevention group (P < 0.01).

CONCLUSION

SM may improve the body fluid metabolism and alleviate the degree of the lung edema by regulating the expression of AQP-1. The results suggest SM can regulate the activity of AQP-1 to improve the water metabolism of ALI.

Thyroid transcription factor-1 facilitates cerebrospinal fluid formation by regulating aquaporin-1 synthesis in the brain

In the brain, aquaporin-1 (AQP-1), a water channel for high osmotic water permeability, is mainly expressed in the apical membrane of the ventricular choroid plexus and regulates formation of cerebrospinal fluid (CSF). Although the physiology of AQP-1 has been the subject of several publications, much less is known about the trans-acting factors involved in the control of AQP-1 gene expression. Here we report that TTF-1, a homeodomain-containing transcriptional regulator, is coexpressed with AQP-1 in the rat brain choroid plexus and enhances AQP-1 gene transcription by binding to conserved core TTF-1-binding motifs in the 5'-flanking region of the AQP-1 gene. Intracerebroventricular administration of an antisense TTF-1 oligodeoxynucleotide significantly decreased AQP-1 synthesis and reduced CSF formation. In addition, blockade of TTF-1 synthesis increased survival of the animals following acute water intoxication-induced brain edema. These results suggest that TTF-1 is physiologically involved in the transcriptional control of AQP-1, which is required for CSF formation.

Toxicity and Biodistribution of a First-Generation Recombinant Adenoviral Vector, Encoding Aquaporin-1, After Retroductal Delivery to a Single Rat Submandibular Gland

Before conducting a phase 1/2 clinical trial of a serotype 5 adenovirus encoding human aquaporin-1 (AdhAQP1) for the treatment of radiation-damaged salivary glands, we have conducted a detailed toxicity and biodistribution study in adult rats. AdhAQP1 (2x108-2x1011 particles) was delivered to a single submandibular gland by retroductal cannulation. Administration of this vector resulted in no animal mortality or morbidities, and no adverse signs of clinical toxicity. In addition, over the 92-day time course of the study, with both male and female rats, there were no consistent treatment-related changes in serum indicators of hepatic, renal, and cardiac functions. Importantly, we also observed no vector-associated effects on either water consumption by, or hematocrit levels in, study animals. However, three suggestive mild gender-related response differences were seen. Female, but not male, rats exhibited small reductions in food consumption (10-15%) and body weight gain (5-10%), and evidence of persistent inflammation, after vector treatment. These were vector, but not dose, related. Three days after delivery of 2x1011 particles of AdhAQP1, vector was detected primarily in the targeted gland; 9 of 10 samples from the targeted gland were positive, whereas only 5 of 90 nonoral samples were positive. There was no evidence of the generation of replication-competent adenovirus in saliva or blood samples. In aggregate, these findings show that localized delivery of AdhAQP1 to salivary glands appears to occur without significant toxicity.

Effect of dexamethasone and aquaporin-1 antisense oligonucleotides on the aquaporin-1 expression in cultured human trabecular meshwork cells

The changes in the expression of aquaporin-1 (AQP1) mRNA and protein in cultured human trabecular meshwork (HTM) cells treated with dexamethasone and transfected with antisense oligonucleotides (AS-ODN) were studied, and the implication of AQP1 regulation in corticosteroid-glaucoma and the possibility of AS-ODN inhibiting the AQP1 expression were evaluated. The cultured HTM cells in vitro were treated with different concentrations of dexamethasone and transfected with oligonucleotides for 5 days respectively. Then, total RNA and protein of HTM cells were extracted. The changes of AQP1 mRNA and protein were demonstrated qualitatively and quantitatively by RT-PCR and Western blot. Band intensities were detected by imaging analysis. There was a parallel relationship between the results of RT-PCR and those of Western blot. The expression levels of AQP1 mRNA and protein in dexamethasone-treated groups were increased initially and decreased later as dexamethasone concentration was stepped up. In the 0. 04 microg/mL and 0.4 microg/mL groups, the levels of AQP1 were higher than in control group (0 microg/mL). In the 4 microg/ mL and 40 microg/mL groups, the AQP1 expression levels were lower than in control group. AS-ODN could down-regulate the expression of AQP1 mRNA and protein in a dose-dependent manner. At 5 microg/mL, down-regulation efficiency reached the maximum. There was no statistically significant difference in the expression of AQP1 mRNA and protein between all sense oligonucleotides groups and control group. It was suggested that dexamethasone may induce the changes of the AQP1 expression in HTM cells to be involved in the occurrence of corticosteroid-glaucoma. AS-ODN can down-regulate the AQP1 expression in HTM cells to some extent.

[Expression of aquaporin-1 in a guinea pig model of labyrinth destruction]

OBJECTIVE

To study the expression of aquaporin-1(AQP-1) in the cochlea and endolymphatic sac in guinea pigs with labyrinth destruction.

METHODS

Chloroform was injected into the tympanum to establish the animal model of labyrinth destruction in guinea pigs, and two-step immunohistochemical method was used to examine the expression of AQP-1 in the cochlea and endolymphatic sac at different time points.

RESULTS

AQP-1 expression was fluctuant in accordance with the morphological changes of the spiral ligament fibrocytes in the cochlea: destruction of the spiral ligament cells was followed by AQP-1 expression down-regulation, and AQP-1 up-regulation occurred with the cell regeneration. But no such changes were observed in the endolymphatic sac.

CONCLUSION

AQP-1 may take part in the maintenance of the structural stability of the spiral ligament.

Expression of aquaporin-9 immunoreactivity by catecholaminergic amacrine cells in the rat retina

Aquaporins are involved in the maintenance of ionic and osmotic balance in the central nervous system and in the eye. Whereas the expression of aquaporin-9 immunoreactivity in the brain has been described for catecholaminergic neurons and glial cells, the expression of aquaporin-9 in the neural retina is unclear. We examined the distribution of aquaporin-1 and -9 immunoreactivities in retinas of the rat. Aquaporin-9 immunoreactivity was expressed exclusively by tyrosine hydroxylase (TH) positive amacrine cells, while aquaporin-1 immunoreactivity was expressed by photoreceptor cells and by TH negative amacrine cells. The staining pattern of aquaporin-9 did not change up to 4 weeks after pressure-induced transient retinal ischemia. It is concluded that catecholaminergic, putatively dopaminergic, amacrine cells of the retina express aquaporin-9.

Establishment and characterization of renal progenitor like cells from S3 segment of nephron in rat adult kidney

Kidney is thought to be a regenerative organ in terms of repair from acute tubular injury. It is unknown whether cell population contributes to repair disordered kidney. We attempted to identify and isolate highly proliferative cells from a single cell. We dissected a single nephron from adult rat kidney. Isolated nephrons were separated into segments and cultured. Outgrowing cells were replated after limiting dilution so that each well contained a single cell. One of cell line which was the most potent to grow was designated as rKS56. rKS56 cells showed cobblestone appearance and expressed immature cell markers relating to kidney development and mature tubular cell markers. rKS56 cells grew exponentially and could be maintained for 300 days without transformation. In different culture conditions, rKS56 cells differentiated into mature tubular cells defined by aquaporin-1, 2 expression, and responsiveness to parathyroid hormone or vasopressin. Engrafted to kidney in rat ischemic reperfusion model, rKS56 cells replaced in injured tubules in part after implantation and improved renal function. These results suggest rKS56 cells possess character such as self-renewal, multi-plasticity and capability of tissue repair. rKS56 may possibly contribute to the future development of cell therapy for renal regeneration.

[The action of dexamethasone on trans epithelial electrical resistance and the expression of aquaporin-1 in immortalized trabecular cells]

OBJECTIVE

To study the effect of dexamethasone on trans epithelial electrical resistance (TEER) and the expression of AQP-1 in immortalized trabecular cells.

METHODS

Immortalized human trabecular cells were cultured on PET membrane in 24 wells plate. The cells were treated with Dexamethasone in concentration of 10(-7) mol/L. After the cultured cell became confluence, TEER of the cells was detected to evaluate the resistance of outflow pathway at different time points. Western blot was used to analyze the expression of AQP-1 in the trabecular cells.

RESULTS

The TEER and the expression of AQP-1 were much higher in the cells treated by Dexamethasone in comparison to control without dexamethasone exposure.

CONCLUSIONS

The TEER and expression of AQP-1 in immortalized trabecular cells can be enhanced by Dexamethasone. AQP-1 upregulation induced by Glucocorticoid may relate with the increased resistance of outflow pathway in glaucoma.

Distribution of sodium transporters and aquaporin-1 in the human choroid plexus

The choroid plexus epithelium secretes electrolytes and fluid in the brain ventricular lumen at high rates. Several channels and ion carriers have been identified as likely mediators of this transport in rodent choroid plexus. This study aimed to map several of these proteins to the human choroid plexus. Immunoperoxidase-histochemistry was employed to determine the cellular and subcellular localization of the proteins. The water channel, aquaporin (AQP) 1, was predominantly situated in the apical plasma membrane domain, although distinct basolateral and endothelial immunoreactivity was also observed. The Na(+)-K(+)-ATPase alpha(1)-subunit was exclusively localized apically in the human choroid plexus epithelial cells. Immunoreactivity for the Na(+)-K(+)-2Cl(-) cotransporter, NKCC1, was likewise confined to the apical plasma membrane domain of the epithelium. The Cl(-)/HCO(3)(-) exchanger, AE2, was localized basolaterally, as was the Na(+)-dependent Cl(-)/HCO(3)(-) exchanger, NCBE, and the electroneutral Na(+)-HCO(3)(-) cotransporter, NBCn1. No immunoreactivity was found toward the Na(+)-dependent acid/base transporters NHE1 or NBCe2. Hence, the human choroid plexus epithelium displays an almost identical distribution pattern of water channels and Na(+) transporters as the rat and mouse choroid plexus. This general cross species pattern suggests central roles for these transporters in choroid plexus functions such as cerebrospinal fluid production.

[Screening differentially expressed genes in denucleated K562 cells with restriction display technique]

OBJECTIVE

To screen differentially expressed genes in cytochalasin B (CB)-induced denucleated K562 cells by restriction display (RD) technique.

METHODS

The total RNA was isolated and purified from K562 cells before and after CB (10 mug/ml) treatment. The mRNA from both treated and untreated K562 cells were reversely transcribed into cDNA, and the differentially expressed genes were separated using RD technique combined with polyacrylamide gel electrophoresis and sliver staining, followed by cloning, sequencing and homology analysis against GenBank database of these genes.

RESULTS

Seven differentially expressed genes were identified in CB-treated cells including aquaporin 1 (AQP1) gene, which was verified to be up-regulated after CB treatment by RT-PCR.

CONCLUSION

AQP1 gene might be in close association with the regulation of denucleation processes and CB-induced proliferation inhibition of K562 cells.

The influence of aquaporin-1 and microvessel density on ovarian carcinogenesis and ascites formation

This study aimed at investigating aquaporin-1 (AQP1) distribution and expression in primary ovarian epithelial tumors, correlating with clinicopathologic variables and intratumoral microvessel density (IMD). The AQP1 expression and IMD in 105 cases with primary epithelial ovarian tumors were measured by semiquantitative immunohistochemical technique. AQP1 was located mainly in microvessels and small vessels but seldom in tumor cells. Expression of AQP1 and IMD in ovarian malignant tumors was significantly higher than that in borderline tumors (P= 0.000, P= 0.001, respectively), and that in borderline tumors was higher than in benign tumors (P= 0.008, P= 0.028, respectively). The expression of AQP1 in FIGO stage III-IV was more than that in stage I-II (P= 0.001), and cases with ascites volume greater than 1000 mL were more than cases with ascites volume less than 1000 mL (P= 0.000). There is a positively correlated relationship between expression of AQP1 and IMD (correlation coefficient 0.60, P= 0.000) and between expression of AQP1 and ascites volume (correlation coefficient 0.57, P= 0.000). These data implicate that high AQP1 expression may play an important role in the ovarian carcinogenesis, progression, and ascites formation. Further studies into the mechanism of AQP1 regulation and the relationship between AQP1 expression and tumor angiogenesis may lead to novel therapies for ovarian carcinoma.

Effect of Cortisol on Aquaporin Expression in the Esophagus of the European Eel,Anguilla anguilla

Long-term cortisol infusion into freshwater (FW)-adapted eels induced a significant increase in aquaporin-1 (AQP1) mRNA expression within the esophageal epithelium of migratory "silver" eels, but not in nonmigratory, immature "yellow" eels. Cortisol treatment had no significant effect on the mRNA abundance of a second aquaporin-1 isoform, termed AQP1dup, which exhibited a highly variable expression profile among individual members of all fish groups. These results suggest that cortisol, at plasma concentrations similar to that found during FW/seawater (SW) acclimation, induces upregulation in AQP1 expression and thus increases esophageal water permeability during the migration of eels to the SW environment.

Immunocytochemical and Phylogenetic Distribution of Aquaporins in the Frog Ventral Skin and Urinary Bladder

We recently cloned three cDNAs encoding frog aquaporin (AQP-h1, BAC07470; AQP-h2, BAC82379; and AQP-h3, BAC07471) from the ventral pelvic skin of the tree frog, Hyla japonica. The present study demonstrated that Hyla AQP-h2 was translocated from cytoplasmic pools to the apical plasma membranes of the granular cells in the bladder after antidiuretic hormone stimulation and that Hyla AQP-h2 and AQP-h3 behaved similarly in the ventral pelvic skin. Further, we found that terrestrial and tree frogs, but not aquatic and semiterrestrial-adapted frogs, absorbed water from their ventral pelvic skin by AQP-h3-like protein in concert with AQP-h2-like protein.

Expression and distribution of aquaporin-1 in nasal polyps: does it have any significance in edema formation?

BACKGROUND

The aim of this study was to investigate the expression of Aquaporin 1 (AQP1) and AQP4 in polyp tissue.

METHODS

Nasal polyps were obtained from 34 patients with nasal polyposis during endoscopic sinus surgery. Bullous middle turbinates with normal-appearing mucosa of 10 patients were used as controls. Expression of AQP1 and AQP4 water channels were determined by immunohistochemical methods.

RESULTS

AQP1 has been found to be expressed in fibroblasts located in polyp tissue, especially in the subepithelial area, periphery of seromucous glands, and endothelial cells of venules.

CONCLUSION

We have established a high expression of AQP1 water channels in nasal polyp tissue and have suggested two mechanisms to explain this finding. Increased AQP1 expression may be a cause or a consequence of edema formation. Thus, additional studies are needed to elucidate the true mechanism underlying this relationship.

Regulatory effect of dexamethasone on aquaporin-1 expression in cultured bovine trabecular meshwork cells

To evaluate the effect of dexamethasone on the expression of aquaporin-1 (AQP-1) in cultured bovine trabecular meshwork cells, bovine trabecular meshwork cells were cultured in vitro and reproduced to the third and the fourth generation, then treated with dexamethasone at the concentrations of 5, 25, 50, 250 microg/L respectively for 7 days. Immunohistochemical technique-supervision method was employed to measure, and image analysis system to analyze the expression of AQP-1 in normal cultured bovine trabecular meshwork cells and those treated with dexamethasone. In normal bovine trabecular meshwork cells, the grayscale of AQP-1 positive staining was 167.94 +/- 1.18, while it was 168.92 +/- 0.91, 176.72 +/- 1.80, 180.64 +/- 1.31, 185.64 +/- 1.58 in cells treated with 5, 25, 50, 250 microg/L concentrations of dexamethasone. When the concentration of dexamethasone was higher than 25 microg/L, the expression of AQP-1 was significantly inhibited (P < 0.05). The regulation of AQP-1 expression by dexamethasone in cultured bovine trabecular meshwork cells in vitro may be one of causes that retard the aqueous outflow in glucocorticoid- induced glaucoma.

[Influence of estradiol benzoate on fluid reabsorption capacity of rat efferent ductuli]

OBJECTIVE

To study the influence of estradiol benzoate (E2B) on the fluid reabsorption capacity of rat efferent ductuli.

METHODS

Newborn male Sprague-Dawley rats were injected subcutaneously with E2B (0.2 mg/5 g body weight), and the histological morphology of efferent ductulus, epithelial ultrastructure, and immunoexpression of AQP-1 were investigated on postnatal day 14, 21, 28, 42 and 56, respectively. Vehicle was given to the controls.

RESULTS

After exposure to E2B, the lumina of the efferent ductuli dilated greatly (P < 0.05), and the epithelium height decreased significantly (P < 0.01), microvilli of nonciliated cells short and sparse, endocytic apparatus implicated in fluid reabsorption scarce, and with no AQP-1 expression.

CONCLUSION

High dosage of E2 B neonatally administrated to rats damages the fluid reabsorption capacity of efferent ductuli.

Impairment of NtAQP1 gene expression in tobacco plants does not affect root colonisation pattern by arbuscular mycorrhizal fungi but decreases their symbiotic efficiency under drought

We investigated in two tobacco (Nicotiana tabacum) plant lines (wildtype or antisense mutant) whether impairment in expression of the plasma membrane aquaporin gene (NtAQP1) affects the arbuscular mycorrhizal (AM) fungal colonisation pattern or the symbiotic efficiency of AM fungi. These two objectives were investigated under well-watered and drought stress conditions. Both plant lines had a similar pattern of root colonisation under well-watered and drought stress conditions. In contrast, under drought stress, AM wildtype plants grew faster than mycorrhizal antisense plants. Plant gas exchange also appeared to depend on the expression of NtAQP1 and parallelled the determined growth increments. The implications of enhanced symplastic water transport via NtAQP1 for the efficiency of the AM symbiosis under drought stress conditions are further discussed.

[Protein and mRNA expression of aquaporin-1 in epithelial ovarian tumors and its clinic significance]

OBJECTIVE

To investigate protein and mRNA expression of aquaporin-1 (AQP1) in epithelial ovarian tumors and its clinic significance.

METHODS

The protein and mRNA expressions of AQP1 were measured by immunohistochemical technique, western blot and RT-PCR in 65 cases of epithelial ovarian tumors and 13 cases of normal ovary tissue.

RESULTS

AQP1 located in microvascular and small vessel epithelial cells. The protein and mRNA expressions of AQP1 in ovarian cancer (0.39 +/- 0.12, 0.93 +/- 0.51, respectively) and ovarian borderline tumors (0.43 +/- 0.21, 0.95 +/- 0.34, respectively) were significantly higher than that of ovarian benign tumors (0.27 +/- 0.13, 0.51 +/- 0.41, respectively; P < 0.05) and normal ovary tissue (0.24 +/- 0.13, 0.34 +/- 0.29, respectively; P < 0.05). Of all ovarian cancers, expression of AQP1 in cases with ascites more than 1000 ml (0.46 +/- 0.13, 1.25 +/- 0.57, respectively) was higher than that of ascites less than 1 approximately 499 ml (0.35 +/- 0.11, 0.75 +/- 0.45, respectively; P < 0.05).

CONCLUSION

Over-expression of AQP1 plays an important role in development of epithelial ovarian tumors, and may be related with formation of ascites of ovarian carcinoma.

Aquaporin-1 in the choroid plexuses of developing mammalian brain

The normal brain develops within a well-controlled stable internal "milieu" protected by specialised mechanisms referred to collectively as blood-brain barriers. A fundamental feature of this environment is the control of water flow in and out of the developing brain. Because of limited vascularisation of the immature brain, choroid plexuses, via the cerebrospinal fluid, have been proposed as the main route of fluid exchange between the blood and brain interfaces. We describe the temporal expression and appearance of aquaporin-1 (AQP1) which is important for water transfer across adult choroid plexuses. AQP1 expression was studied in rat embryos using real time reverse transcription/polymerase chain reaction. mRNA for AQP1 was present in rat brain at embryonic day 12 (E12) one day before the protein was detectable in the fourth ventricular choroid plexus (the first plexus to appear); its relative levels increased at E13-E14 when more AQP1-immunoreactive cells appeared in all plexuses. The presence of AQP1 was determined immunocytochemically in five different mammalian species (rat, mouse, human, sheep and opossum) in all four choroid plexuses from their earliest appearance. In all five species studied, the appearance of AQP1 immunoreactivity followed the same developmental sequence: the fourth, lateral and, finally, third ventricular choroid plexus. The stage of choroid plexus development when AQP1 was first detected in all five species and in all four choroid plexuses corresponded to the transition between Stages I and II. The cellular localisation of AQP1 in all choroid plexuses, as soon as it was detectable, had the characteristic apical membrane distribution previously described in the adult; a basolateral membrane localisation was also observed.

[Expressions of aquaporin-1 on peritonea in hepatic cirrhotic rats with ascites]

OBJECTIVE

To investigate the changes of aquaporin (AQP-1) expressions on peritonea in liver cirrhotic rats with ascites, and to study the correlation between AQP-1 expressions and ascites form.

METHODS

32 healthy Sprague-Dawley (SD) rats were divided into two groups randomly, 20 rats were used to produce liver cirrhotic models induced with phenobarbitol sodium and CCl(4). The distribution and protein expressions of AQP-1 on the rats' peritonea were measured with immunohistochemistry assay, and the expressions of APQ-1 mRNA were tested with relative GAPDH quantitative RT-PCR.

RESULTS

(1) The expressions of AQP-1 were mainly on the endothelial cells of capillary vessels and venules on the rats' peritonea, and also on mesothelial cells. (2) There was no statistically significant difference between the expressions of AQP-1 protein and mRNA in the two groups on the early stage of liver cirrhosis. (3) Downregulations of the expressions of AQP-1 protein and mRNA were observed in B group on the advanced cirrhotic stage.

CONCLUSION

Expressions of AQP-1 were downregulated on the peritonea of rats with decompensated liver cirrhosis, which may play a role in the formation of ascites. The changes of AQP-1 Expressions on peritoneal mesothelial cells which were fewer than those on the endothelial cells may be few relations to ascites form.

Expression of the Aquaporin-1 Water Channel in Human Glial Tumors

OBJECTIVE

Malignant glial tumors are associated with cerebral edema. The aquaporins (AQPs) are a family of membrane proteins that provide a major pathway for water transport in mammals. In the central nervous system, AQP1 is selectively expressed in the choroid plexus and thought to participate in cerebrospinal fluid production. Prior studies have suggested that AQP1 may be up-regulated in glial tumors, potentially contributing to tumor-associated edema. The objective of this study was to investigate the expression of AQP1 in a large series of human glial tumors.

METHODS

Thirty-six human glial tumors were obtained from the University of California, San Francisco Neurosurgery Tissue Bank. AQP1 expression was evaluated by reverse transcriptase polymerase chain reaction, complementary deoxyribonucleic acid gene array, Western blot analysis, and immunohistochemical analyses.

RESULTS

AQP1, normally restricted to choroid epithelia, was highly expressed in glioblastomas. Complementary deoxyribonucleic acid array, Western blot analysis, and immunohistochemical analysis revealed intense up-regulation of AQP1 expression in all glioblastomas studied.

CONCLUSION

The abnormal up-regulation of AQP1 in glial tumors suggests a potential pathological role for this membrane water channel and raises the possibility that selective AQP1 inhibition might offer a new therapeutic target for treatment of tumor-associated edema.

[Rat alveolar type II injured by bleomycin]

OBJECTIVE

To explore dysfunction mechanism of rat alveolar type II (AT-II) injured by bleomycin (BLM).

METHODS

SD rats were injected with a single intratracheal dose of bleomycin or control saline. On day 7, 14, and 28 following intratracheal bleomycin or saline instillation, animals were killed under overdose of 1.5% sodium pentobarbital (0.25 ml/100 g, i.p.) and bronchoalveolar lavage fluid (BALF) from the lung was tested for the activity of pulmonary surfactant (PS) by the Whihelmy Film Balance. Several concentrations of bleomycin stimulated the culture of rat AT-II cells, and surfactant protein (SP) A, B, and aquaporin-1 (AQP) mRNA were analyzed by fluorescent quantitative polymerase chain reaction (FQ-PCR).

RESULTS

The activity of PS and hypoxemia significantly decreased on day 7 and improved on day 14 and completely recovered to normal status on day 28. SP-A, B, and AQP-1 mRNA expression in BLM-stimulated group were significantly lower than those in the control group (P<0.001).

CONCLUSION

BLM-injured AT-II cells decrease the levels of SP-A, B, and AQP-1 mRNA and cause PS dysfunction, resulting in hypoxemia and pneumonedema.