• KSBB Journal
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• 제28권6호
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• pp.394-399
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• 2013

Astragalus membranaceus Bunge is used in herbal medicine in Eastern Asian countries including Korea. In this study, we assessed the effects of A. membranaceus extract (AM) on the aquaporin-3 (AQP3) protein expression in HaCaT cells. AM did not affect viability of HaCaT cells. AQP3 expression and cell migration seem to be maximal at $100{\mu}g/mL$ concentration. Epidermal growth factor receptor (EGFR) kinase inhibitor, PD153035, blocked AM-induced AQP3 expression and cell migration. In addition, an 80% ethanol extracts of herbal prescription, SinhyoTakleesan (ST), which is composed of A. membranaceus, Angelicae gigantis, Glycyrrhiza glabra Linne, and Lonicera japonica Flos also induced AQP3 expression at $20{\mu}g/mL$ in HaCaT cells. Collectively, these results suggest that AM induce AQP3 expression via EGFR pathway.

• Journal of Korean Neurosurgical Society
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• 제41권1호
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• pp.30-38
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• 2007

Objective : To elucidate the role of aquaporin-4[AQP4] in cerebral edema formation, we studied the expression and subcellular localization of AQP4 in astrocytes after focal cerebral ischemia. Methods : Cerebral ischemia were induced by permanent middle cerebral artery[MCA] occlusion in rats and estimated by the discoloration after triphenyltetrazolium chloride[TTC] immersion. Change of AQP4 expression were evaluated using western blot. Localization of AQP4 was assessed by confocal microscopy and its interaction with ${\alpha}-syntrophin$ was analyzed by immunoprecipitation. Results : After right MCA occlusion, the size of infarct and number of apoptotic cells increased with time. The ratio of GluR1/GluR2 expression also increased during ischemia. The polarized localization of AQP4 in the endfeet of astrocytes contacting with ventricles, vessels and pia mater was changed into the diffuse distribution in cytoplasm. The interactions of AQP4 and Kir with ${\alpha}-syntrophin$, an adaptor of dystrophin complex, were disrupted by cerebral ischemia. Conclusion : The deranged spatial buffering function of astrocytes due to mislocalized AQP4/Kir4.1 channel as well as increased assembly of $Ca^{2+}$ permeable AMPA receptors might contribute to the development of edema formation and the excitotoxic neuronal cell death during ischemia.

• Childhood Kidney Diseases
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• 제20권1호
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• pp.11-17
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• 2016

Appropriate control of diet and water intake is important for maintaining normal blood pressure, fluid and electrolyte homeostasis in the body. It is relatively understood that the amount of sodium and potassium intake directly affects blood pressure and regulates ion transporters; Na and K channel functions in the kidney. However, little is known about whether diet and water intake regulates Aquaporin (AQP) function. AQPs, a family of aquaporin proteins with different types being expressed in different tissues, are important for water absorption by the cell. Water reabsorption is a passive process driven by osmotic gradient and water permeability is critical for this process. In most of the nephron, however, water reabsorption is unregulated and coupled to solute reabsorption, such as AQP1 mediated water absorption in the proximal tubule. AQP2 is the only water channel founded so far that can be regulated by hormones in the kidney. AQP2 expressed in the apical membrane of the principal cells in the collecting tubule can be regulated by vasopressin (antidiuretic hormone) controlling the final volume of urine excretion. When vasopressin binds to its receptor on the collecting duct cells, it stimulates the translocation of AQP2 to the membrane, leading to increased water absorption via this AQP2 water channel. However, some studies also indicated that the AQP2 is also been regulated by vasopressin independent mechanism. This review is focused on the regulation of AQP2 by diet and the amount of water intake on salt and water homeostasis.

• IMMUNE NETWORK
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• 제21권5호
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• pp.34.1-34.16
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• 2021

Sjögren's syndrome (SS) is an autoimmune disease characterized by dryness of the mouth and eyes. The glandular dysfunction in SS involves not only T cell-mediated destruction of the glands but also autoantibodies against the type 3 muscarinic acetylcholine receptor or aquaporin 5 (AQP5) that interfere with the secretion process. Studies on the breakage of tolerance and induction of autoantibodies to these autoantigens could benefit SS patients. To break tolerance, we utilized a PmE-L peptide derived from the AQP5-homologous aquaporin of Prevotella melaninogenica (PmAqp) that contained both a B cell "E" epitope and a T cell epitope. Repeated subcutaneous immunization of C57BL/6 mice with the PmE-L peptide efficiently induced the production of Abs against the "E" epitope of mouse/human AQP5 (AQP5E), and we aimed to characterize the antigen specificity, the sequences of AQP5E-specific B cell receptors, and salivary gland phenotypes of these mice. Sera containing anti-AQP5E IgG not only stained mouse Aqp5 expressed in the submandibular glands but also detected PmApq and PmE-L by immunoblotting, suggesting molecular mimicry. Characterization of the AQP5E-specific autoantibodies selected from the screening of phage display Ab libraries and mapping of the B cell receptor repertoires revealed that the AQP5E-specific B cells acquired the ability to bind to the Ag through cumulative somatic hypermutation. Importantly, animals with anti-AQP5E Abs had decreased salivary flow rates without immune cell infiltration into the salivary glands. This model will be useful for investigating the role of anti-AQP5 autoantibodies in glandular dysfunction in SS and testing new therapeutics targeting autoantibody production.

• The Korean Journal of Physiology and Pharmacology
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• 제7권3호
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• pp.181-185
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• 2003

Whether there exists a sympathetic neural regulation on the aquaporin (AQP) channels in the kidney was examined. Male Sprague-Dawley rats were used. They were renal nerve denervated by stripping the nervous and connective tissues passing along the renal artery and vein, and painting these vessels with 10% phenol solution through a midline abdominal incision. Three days later, the expression of AQP1-4 proteins in the denervated kidneys was determined. The content of norepinephrine was found significantly decreased following the denervation. Accordingly, the expression of AQP2 proteins was markedly decreased. The expression of AQP3 and AQP4 was also slightly but significantly decreased, while that of AQP1 was not. Neither the basal nor the AVP-stimulated accumulation of cAMP was significantly affected in the denervated kidney. It is suggested that the sympathetic nervous system has a tonic stimulatory effect on AQP channels in the kidney.

• 한국발생생물학회지:발생과생식
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• 제22권3호
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• pp.263-273
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• 2018

Aquaporin (AQP) 3, a facilitated transporter of water and glycerol, expresses in placenta and fetal membranes, but the detailed localization and function of AQP3 in placenta remain unclear. To elucidate a role of AQP3 in placenta, we defined the expression and cellular localization of AQP3 in placenta and fetal membranes, and investigated the structural and functional differences between wild-type and AQP3 null mice. Gestational sacs were removed during mid-gestational period and amniotic fluid was aspirated for measurements of volume and composition. Fetuses with attached placenta and fetal membranes were weighed and processed for histological assessment. AQP3 strongly expressed in basolateral membrane of visceral yolk sac cells of fetal membrane, the syncytiotrophoblasts of the labyrinthine placenta and fetal nucleated red blood cell membrane. Mice lacking AQP3 did not exhibit a significant defect in differentiation of trophoblast stem cells and normal placentation. However, AQP3 null fetuses were smaller than their control litter mates in spite of a decrease in litter size. The total amniotic fluid volume per gestational sac was reduced, but the amniotic fluid-to-fetal weight ratio was increased in AQP3 null mice compared with wild-type mice. Glycerol, free fatty acid and triglyceride levels in amniotic fluid of AQP3 null mice were significantly reduced, whereas lactate level increased when compared to those of wild-type mice. These results suggest a role for AQP3 in supplying nutrients from yolk sac and maternal blood to developing fetus by facilitating transport of glycerol in addition to water, and its implication for the fetal growth in utero.

• 한국동물생명공학회지
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• 제35권4호
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• pp.315-322
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• 2020

Aquaporin channels (AQPs) are known to play an important role in the development of ovarian follicles through their function in water transport pathways. Compared to other AQPs, research on the role of AQP4 in female reproductive physiology, particularly in cattle, remains limited. In our previous study, gene chip microarray data showed a downregulation of AQP4 in bovine cystic follicles. This study was performed to validate the AQP4 expression level at the protein level in bovine follicles using immunohistochemistry, Western blotting, and immunoprecipitation assays. Immunostaining data showed that AQP4 was expressed in granulosa and theca cells of bovine ovarian follicles. The ovarian follicles were classified according to size as small (< 10 mm) or large (> 25 mm) in diameter. Consistent with earlier microarray data, semi-quantitative PCR data showed a decrease in AQP4 mRNA expression in large follicles. Western blot analysis showed a downregulation of the AQP4 protein in large follicles. In addition, AQP4 was immunoprecipitated and blotted with anti-AQP4 antibody in small and large follicles. Accordingly, AQP4 exhibited a low expression in large follicles. These results show that AQP4 is downregulated in bovine ovarian large follicles, suggesting that the downregulation of AQP4 expression may interfere with follicular water transport, leading to bovine follicular cysts.

• Biomolecules & Therapeutics
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• 제31권6호
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• pp.648-654
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• 2023

Oxidative stress-induced melanocyte apoptosis is linked to the immune system and plays a critical role in the pathogenesis of vitiligo. Aquaporin-3 (AQP3), which is downregulated in vitiligo keratinocytes, regulates intracellular H₂O₂ accumulation. However, the role of AQP3 in oxidative stress is uncertain in vitiligo. This study investigated the effect of downregulated AQP3 on oxidative stress in vitiligo using lesional and non-lesional skin specimen sets from vitiligo patients and primary cultured adult normal human epidermal keratinocytes, with or without downregulation and overexpression of AQP3 in the presence or absence of H₂O₂ treatment. The levels of nuclear factor E2-related factor 2 (NRF2) and/or its main target, NAD(P)H quinone dehydrogenase 1 (NQO-1), were lower in the lesional keratinocytes and cultured keratinocytes with AQP3 knockdown, but were increased in keratinocytes upon AQP3 overexpression. Ratios of NRF2 nuclear translocation and NQO-1 expression levels were further reduced in AQP3-knockdown keratinocytes following H₂O₂ treatment. The conditioned media from AQP3-knockdown keratinocytes treated with H₂O₂ contained higher concentrations of reactive oxygen species (ROS). Moreover, the number of viable melanocytes was reduced when the conditioned media were added to the culture media. Overall, AQP3 downregulation in the keratinocytes of patients with vitiligo can induce oxidative stress in neighboring melanocytes, leading to melanocyte death.

• The Korean Journal of Physiology and Pharmacology
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• 제23권2호
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• pp.113-120
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• 2019

Mannosylerythritol lipids (MELs) are glycolipids and have several pharmacological efficacies. MELs also show skin-moisturizing efficacy through a yet-unknown underlying mechanism. Aquaporin-3 (AQP3) is a membrane protein that contributes to the water homeostasis of the epidermis, and decreased AQP3 expression following ultraviolet (UV)-irradiation of the skin is associated with reduced skin moisture. No previous study has examined whether the skin-moisturizing effect of MELs might act through the modulation of AQP3 expression. Here, we report for the first time that MELs ameliorate the UVA-induced downregulation of AQP3 in cultured human epidermal keratinocytes (HaCaT keratinocytes). Our results revealed that UVA irradiation decreases AQP3 expression at the protein and messenger RNA (mRNA) levels, but that MEL treatment significantly ameliorated these effects. Our mitogen-activated protein kinase inhibitor analysis revealed that phosphorylation of c-Jun N-terminal kinase (JNK), but not extracellular signal-regulated kinase or p38, mediates UVA-induced AQP3 downregulation, and that MEL treatment significantly suppressed the UVA-induced phosphorylation of JNK. To explore a possible mechanism, we tested whether MELs could regulate the expression of peroxidase proliferator-activated receptor gamma ($PPAR-{\gamma}$), which acts as a potent transcription factor for AQP3 expression. Interestingly, UVA irradiation significantly inhibited the mRNA expression of $PPAR-{\gamma}$ in HaCaT keratinocytes, whereas a JNK inhibitor and MELs significantly rescued this effect. Taken together, these findings suggest that MELs ameliorate UVA-induced AQP3 downregulation in HaCaT keratinocytes by suppressing JNK activation to block the decrease of $PPAR-{\gamma}$. Collectively, our findings suggest that MELs can be used as a potential ingredient that modulates AQP3 expression to improve skin moisturization following UVA irradiation-induced damage.

• Asian Pacific Journal of Cancer Prevention
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• 제16권9호
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• pp.3973-3976
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• 2015

Objectives: To explore the expression of aquaporin 1 ($AQP_1$) in bladder uroepithelium cell carcinoma (BUCC) and its relevance to recurrence. Materials and Methods: Tissue samples from 45 BUCC patients who underwent total cystectomy or transurethral resection of bladder tumor (TURBT) and from 40 patients with non-bladder cancers who underwent special detection or treatments were collected. The level of expression of $AQP_1$ in BUCC tissues and normal bladder tissues was assessed by immunohistochemistry so as to analyze the relevance to pathological patterns and time of recurrence in BUCC patients. Results: The expression levels of $AQP_1$ normal bladder tissues and BUCC tissues were $2.175{\pm}0.693$ and $3.689{\pm}0.701$, respectively, and the difference was significant (t=9.99, P<0.0001). Marked increase was noted with BUCC histological grade and pathological stage (P<0.01). Moreover, the expression of $AQP_1$ was evidently higher in cancerous tissues with lymph node metastasis than in those without (P<0.01). With short-term recurrence, the positive cell expression rate of $AQP_1$ was higher in primary tissues, which increased obviously after recurrence. Additionally, the recurrent time of BUCC was negatively associated with the positive cell expression rate of $AQP_1$ and the difference between the expression of $AQP_1$ before and after recurrence (r=-0.843, F=39.302, P=0.000; r=-0.829, F=35.191, P=0.000). Conclusions: $AQP_1$, which reflects the grade, stage, lymph node metastasis and recurrence of BUCC, has potential guiding significance in the diagnosis and treatment of bladder cancarcinoma.