• 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.

• 한국수정란이식학회지
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• 제30권1호
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• pp.17-21
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• 2015

Alteration in ion channel or transporter expression levels affects cell volume which is produced by movement of water and ion across the plasma membrane. In particular, aquaporin (AQP) channels among ion channels play a crucial role in movement of water across the cell membrane. This study was performed to identify whether AQP expression is changed in bovine follicular cystic follicles using microarray, RT-PCR and Western blotting analyses. In microarray data, AQP4 expression was decreased, whereas AQP7 was increased in cystic follicles. Additional experiments were focused on the AQP7 expression increased in cystic follicles. The microarray data was confirmed by semi-quantitative polymerase chain reaction (PCR) and Western blot analysis. AQP7 mRNA and protein expressions were significantly increased in the cystic follicles (p<0.05). Application of estrogen ($10{\mu}g/ml$) to bovine ovarian cells showed a trend of increase in AQP7 expression. From these results, we suggest that the increase in AQP7 expression in cystic follicles may play an important role in movement of water in bovine ovary. In addition, AQP7, a aquaglyceroporin permeating water and glycerol, could be a good target in development of methods for the cryopreservation of bovine ovary.

• 미생물학회지
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• 제47권4호
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• pp.295-301
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• 2011

아쿠아포린(aquaporin)은 MIP (Major Intrinsic Protein) 패밀리에 속하는 물 수송 채널(water transport channel) 단백질로 단세포 생물인 박테리아부터 다세포 고등생물인 인간에 이르기까지 다양한 기관계에서 잘 보존되어 있다. 아쿠아포린은 정통아쿠아포린(orthodox aquaporin)과 아쿠아글리세로포린(aquaglyceroporin)으로 구분되는데, 정통아쿠아포린은 주로 세포내의 물 유입 및 수송에 관여하며 아쿠아글리세로포린은 glycerol, polyol, urea를 비롯한 작은 비극성 분자의 수송에 관여하는 것으로 알려져 있다. 최근까지 효모에서 아쿠아포린 기능이 일부 밝혀졌지만 Aspergillus 속을 포함하는 사상성 진균에서는 거의 연구가 되어있지 않은 실정이다. 본 연구에서는 A. nidulans의 유전체 염기서열 정보를 분석하여 하나의 정통아쿠아포린(aqpA)과 네 개의 아쿠아글리세로포린(aqpB-E)을 발견하였다. 이를 바탕으로 aqpA 유전자 결실돌연변이들을 만들어 그 기능을 분석하였다. aqpA 결실돌연변이는 각종 삼투 스트레스(osmotic stress)에서는 표현형의 변화가 거의 관찰되지 않았으며 이는 이들 유전자가 삼투 스트레스에 반응하지 않거나 유전자의 중복성 때문으로 여겨진다. 그러나 항진균제인 fluconazol에 대해서 그 감수성이 적어지는 것이 관찰 되었다. 이는 aqpA 유전자가 삼투스트레스 반응보다 항진균제의 감지에 더 기능을 가지고 있을 수 있음을 시사한다.

• 생명과학회지
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• 제10권5호
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• pp.456-466
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• 2000

Aquaperin 4 (AQP4) is the mercurial water channel expressed abundantly in brain, especially the region related with cerebrospinal fluid reabsorption and osmoregulation. The primary structure of AQP4 water channel was elucidated but the molecular mechanism of AQP4 channel regulation is still unknown. To investigate the possible regulation of AQP4 water channel by phosphorylation via various protein kinases, osmotic water permeability of AQP4 expressed in Xenopus oocytes was measured by videomicroscopy technique. Forskolin (10 $\mu$M) did not affect osmotic water permeability of oocytes injected with AQP4 cRNA, excluding the regulation of AQP4 water cnannel by protein kinase A. Osmotic water permeability (P아래첨자) of AQP4-expressed oocytes was ingibited by the pretreatmeat of BAPTA/AM (up to 500$\mu$M), an intracellular Ca윗첨자 chelator, and calmidazolium (100$\mu$M), a specific Ca윗첨자/calmodulin antagonist, in a dose-dependent manner. The inhibition of osmotic water permeability (P아래첨자) by the calmidazolium treatment was completely reversed by the addition of calyculin A (0.1$\mu$M), a nonspecific phosphatase inhibitor. Phorbol 12-myristate 13-acetate (PMA), a protein kinase C activator, had biphasic effects on osmotic water permeability in AQP4 cRNA injected oocytes depending on its concentration; 21% increase by 100 nM PMA, 35% decrease by 1$\mu$M PMA. These effects were reversed with 2$\mu$M staurosporine, a nonspecific PKC inhibitor. These results suggest that phosphorylation of AQP4 water channel by Ca윗첨자/calmodulin kinase and protein kinase C might regulate the osmotic water permeability.

• 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.

• The Korean Journal of Physiology and Pharmacology
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• 제1권5호
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• pp.495-504
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• 1997

Water transport is mediated by two distinct pathways, diffusional and channel-mediated water transport. The first molecular water channel was identified from human erythrocytes in 1992. Genetically-related proteins from other mammalian tissues have subsequently been identified to transport water, and the group is referred to as th "Aquaporins". Aquaporin-4 (AQP4) is most abundant in the brain, which may be involved in CSF reabsorption and osmoregulation. However, ontogeny and regulatory mechanisms of AQP4 channels have not been reported. Northern blot analysis showed that AQP4 mRNA began to be expressed in the brain just before birth and that its expression gradually increased by PN7 and then decreased at adult level. AQP4 was expressed predominantly in the ependymal cells of ventricles in newborn rats. And then its expression decreased in ependymal cells and increased gradually in other regions including supraoptic and paraventricular nuclei. AQP4 is also expressed in the subfornical organ, in which the expression level is not changed after birth. Cryogenic brain injury did not affect expression of AQP4 mRNA, while ischemic brain injury decreased it. Osmotic water permeability of AQP4 channel expressed in Xenopus oocytes was inhibited by the pretreatment of BAPTA/AM and calmidazolium, a $Ca^{2+}/Calmodulin$ kinase inhibitor, in a dose-dependent manner. These results indicate that the expression and the function of AQP4 channel are regulated by developmental processes and various pathophysiological conditions. These results will contribute to the understanding of fluid balance in the central nervous system and the osmoregulatory mechanisms of the body.

• 대한한방내과학회지
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• 제38권2호
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• pp.259-263
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• 2017

We describe the cases of two patients with chronic subdural hematomas who were treated with Oreong-san. The patients' symptoms improved, as verified by brain computed tomography imaging. Oreong-san may control membrane permeability by inhibiting the aquaporin channel of the outer membrane of a hematoma. We speculate that hydrostatic modulation is a key mechanism underlying the effectiveness of Oreong-san in the treatment of subdural hematomas.

• International Journal of Oral Biology
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• 제43권4호
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• pp.185-191
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• 2018

Alcohol intake is known to affect various organs in the human body, causing reduction of salivation in the oral cavity. Hypo-salivation effect of alcohol is a common feature, but the mechanism in salivary glands is still poorly studied. Therefore, in this study, the changes in salivary secretion and water channel protein (aquaporin5, AQP5) in salivary glands of mice were investigated after ethanol administration. Animals were divided in to 4 groups with the control, 4 g/kg ethanol, 8 g/kg ethanol and 16 g/kg ethanol administration groups. One hour after ethanol administration, saliva was collected from the oral cavity, and the animals were killed and parotid and submandibular glands were extracted to analyze the histopathology, AQP5 immunihistochemistry and AQP5 protein level. According to the results, the salivation rate decreased irrespective of the ethanol dose in mice, and viscosities increased with increase in ethanol dose. However, there were no pathological changes in parotid and submandibular glands due to ethanol administration. Expression of AQP5 in parotid and submandibular glands decreased with increase ethanol administration These results indicate that the reduction of salivary secretion due to acute alcohol intake is closely related to decrease of the water channel protein such as AQP5 in parotid glands and submandibular glands, rather than the damage of salivary glands.

• 대한본초학회지
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• 제25권4호
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• pp.85-93
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• 2010

Objectives : This study aimed at evaluation of the effects of Gastrodiae Rhizoma on brain edema and aquaporin water channel expressions in the brain. Methods : Brain edema following intracerebral hemorrhage (ICH) was induced by the stereotaxic intrastriatal injection of bacterial collagenase type VII in Sprague-Dawley rats. Then ethanol extract of Gastrodiae rhizoma was treated once a day for 3 days. Brain edema % and water contents, and cell size of neurons in the cerebral cortex were examined. Immuno-histochemistry was processed for AQP4, AQP1, and AQP9 expressions in the brain sections and area % of immuno-labeling was analyzed with image analysis. Results : 1. Ethanol extract of Gastrodiae Rhizoma reduced brain edema of ICH induced rats significantly. 2. Ethanol extract of Gastrodiae Rhizoma reduced excessive brain tissue water contents of ICH induced rats significantly. 3. Ethanol extract of Gastrodiae Rhizoma reduced cellular edema of neurons in cerebral cortex of ICH induced rats significantly. 4. Ethanol extract of Gastrodiae Rhizoma reduced AQP4 immuno-positive area % in cerebral cortex and external capsule of ICH induced rat brain significantly. 5. Ethanol extract of Gastrodiae Rhizoma reduced AQP9 immuno-positive area % in glia limitans externa of ICH induced rat brain significantly. Conclusions : These results suggest that Gastrodiae Rhizoma reveals protective effects against brain edema and cytotoxic edema of neurons by means of down-regulation of AQP4 expression in the brain.

• 한국발생생물학회지:발생과생식
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• 제25권4호
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• pp.245-255
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• 2021

The spermatozoa become mature in the epididymis which is divided into initial segment and caput, corpus, and cauda epididymis. The water movement across the epididymal epithelium is important for creating luminal microenvironment for sperm maturation. Aquaporins (Aqps) are water channel proteins, and expression of Aqps is regulated by androgens. The current research was focused to examine expressional regulation of Aqp1 and Aqp9 by an androgenic-anabolic steroid, nandrolone decanoate (ND). The ND at the low dose (2 mg/kg body weight/week) or high dose (10 mg) was subcutaneously administrated into male rats for 2 or 12 weeks. Transcript levels of Aqp1 and Aqp9 were determined by quantitative real-time polymerase chain reaction (PCR) analyses. In the initial segment, level of Aqp1 was decreased with 12 week-treatment, while Aqp9 level was decreased by the high dose treatment for 12 weeks. In the caput epididymis, Aqp9 expression was decreased by the low dose treatment. The 2 week-treatment resulted in an increase of Aqp1 level but a decrease of Aqp9 expression in the corpus epididymis. In the corpus epididymis, the 12 week-treatment at the low dose caused the reduction of Aqp1 and Aqp9 levels, but the high dose treatment resulted in an increase of Aqp1 expression and a decrease of Aqp9 level. In the cauda epididymis, Aqp1 expression was decreased by 2 and 12 week-treatments, while increases of Aqp9 levels was detected with the high dose treatment for 2 weeks and with 12 week-treatment. These findings indicate differential regulation of Aqp1 and Aqp9 expression among epididymal segments by ND.