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Kenichi Ishibashi - One of the best experts on this subject based on the ideXlab platform.
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Quantitative Analysis of Aquaporin Expression Levels during the Development and Maturation of the Inner Ear
Journal of the Association for Research in Otolaryngology, 2017Co-Authors: Takushi Miyoshi, Kenichi Ishibashi, Taro Yamaguchi, Kiyokazu Ogita, Yasuko Tanaka, Hiroaki Ito, Taisuke Kobayashi, Takayuki Nakagawa, Juichi Ito, Koichi OmoriAbstract:Aquaporins (AQPs) are a family of small membrane proteins that transport water molecules across the plasma membrane along the osmotic gradient. Mammals express 13 subtypes of AQPs, including the recently reported “subcellular AQPs”, AQP11 and 12. Each organ expresses specific subsets of AQP subtypes, and in the inner ear, AQPs are essential for the establishment and maintenance of two distinct fluids, endolymph and perilymph. To evaluate the contribution of AQPs during the establishment of inner ear function, we used quantitative reverse transcription polymerase chain reaction to quantify the expression levels of all known AQPs during the entire development and maturation of the inner ear. Using systematic and longitudinal quantification, we found that AQP11 was majorly and constantly expressed in the inner ear, and that the expression levels of several AQPs follow characteristic longitudinal patterns: increasing ( Aqp0 , 1 , and 9 ), decreasing ( Aqp6 , 8 , and 12 ), and peak of expression on E18 ( Aqp2 , 5 , and 7 ). In particular, the expression level of AQP9 increased by 70-fold during P3–P21. We also performed in situ hybridization of Aqp11 , and determined the unique localization of Aqp11 in the outer hair cells. Immunohistochemistry of AQP9 revealed its localization in the supporting cells inside the organ of Corti, and in the root cells. The emergence of AQP9 expression in these cells was during P3–P21, which was coincident with the marked increase of its expression level. Combining these quantification and localization data, we discuss the possible contributions of these AQPs to inner ear function.
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The distribution and function of aquaporins in the kidney: resolved and unresolved questions
Anatomical Science International, 2017Co-Authors: Toshiyuki Matsuzaki, Kenichi Ishibashi, Tomoyuki Yaguchi, Kinue Shimizu, Aoi Kita, Kuniaki TakataAbstract:The membrane water channel aquaporin (AQP) family is composed of 13 isoforms in mammals, eight of which are reportedly expressed in the kidney: AQP1, 2, 3, 4, 6, 7, 8, and 11. These isoforms are differentially expressed along the renal tubules and collecting ducts. AQP1 and 7 are distributed in the proximal tubules, whereas AQP2, 3, and 4 occur in the collecting duct system. They play important roles in the reabsorption of water and some solutes across the plasma membrane. In contrast to other aquaporins found in the kidney, AQP6, 8, and 11 are localized to the cytoplasm rather than to the apical or basolateral membranes. It is therefore doubtful that these isoforms are directly involved in water or solute reabsorption. AQP6 is localized in acid-secreting type A intercalated cells of the collecting duct. AQP8 has been found in the proximal tubule but its cellular location has not yet been defined by immunohistochemistry. AQP11 seems to be localized in the endoplasmic reticulum (ER) of proximal tubule cells. Interestingly, polycystic kidneys develop in AQP11-null mice. Many vacuole-like structures are seen in proximal tubule cells in kidneys of newborn AQP11-null mice. Subsequently, cysts are generated, and most of the mice die within a month due to severe renal failure. Although ER stress and impairment of polycystin-1, the product of the gene mutated in autosomal-dominant polycystic kidney disease, are possible causes of cystogenesis in AQP11-null mice, the exact mechanism of pathogenesis and the physiological function of AQP11 are yet to be resolved.
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Aquaporin water channels in mammals
Clinical and Experimental Nephrology, 2009Co-Authors: Kenichi Ishibashi, Shigeki Hara, Shintaro KondoAbstract:Water channels, aquaporins (AQPs), are a family of small integral plasma membrane proteins that primarily transport water across the plasma membrane. There are 13 members (AQP0–12) in humans. This number is final as the human genome project has been completed. They are divided into three subgroups based on the primary sequences: water selective AQPs (AQP0, 1, 2, 4, 5, 6, 8), aquaglyceroporins (AQP3, 7, 9, 10), and superaquaporins (AQP11, 12). Since no specific inhibitors are yet available, functional roles of AQPs are suggested by AQP null mice and humans. Abnormal water metabolism was shown with AQP1, 2, 3, 4, 5 null mice, especially with AQP2 null mice: fatal at neonate due to diabetes insipidus. Abnormal glycerol transport was shown with AQP3, 7, 9 null mice, although they appeared normal. AQP0 null mice suffer from cataracts, although the pathogenesis is not clear. Unexpectedly, AQP11 null mice die from uremia as a result of polycystic kidneys. Interestingly, AQP6, 8, 10, 12 null mice are almost normal. AQP null humans have been reported with AQP0, 1, 2, 3, 7: only AQP2 null humans show an outstanding phenotype, diabetes insipidus. This review summarizes the current knowledge on all mammalian AQPs and hopefully will stimulate future research in both clinical and basic fields.
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Cloning and functional expression of a new aquaporin (AQP9) abundantly expressed in the peripheral leukocytes permeable to water and urea, but not to glycerol.
Biochemical and biophysical research communications, 1998Co-Authors: Kenichi Ishibashi, Fumiaki Marumo, Michio Kuwahara, Yujiro Tanaka, Sei SasakiAbstract:A new member (AQP9) of the aquaporin family was identified from human leukocytes by homology cloning using PCR. A full length clone was obtained by screening human liver cDNA library. AQP9 encodes a 295-amino-acid protein with the amino acid sequence identity with AQP3 (48%), AQP7 (45%), and other aquaporins (approximately 30%), suggesting that AQP3, AQP7, and AQP9 belong to a subfamily of the aquaporin family. Injection of AQP9-cRNA into Xenopus oocytes stimulated the osmotic water permeability 7-folds with a low activation energy (4.2 kcal/mol) which was inhibited by 0.3 mM mercury chloride by 48%. AQP9 also facilitated urea transport 4-folds. However, in contrast to AQP3 and AQP7, AQP9 did not stimulate the glycerol permeability, suggesting a unique permeability character. Northern blot analysis revealed the high expression of 3.5-kb messages in peripheral leukocytes >> liver > lung = spleen, but not in thymus. The possible role of AQP9 in the immunological function of leukocytes is intriguing and the identification of AQP9 with unique permeability profile may expand our understanding of water and small solute transport in the body.
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cloning and functional expression of a new aquaporin AQP9 abundantly expressed in the peripheral leukocytes permeable to water and urea but not to glycerol
Biochemical and Biophysical Research Communications, 1998Co-Authors: Kenichi Ishibashi, Fumiaki Marumo, Michio Kuwahara, Yujiro Tanaka, Sei SasakiAbstract:Abstract A new member (AQP9) of the aquaporin family was identified from human leukocytes by homology cloning using PCR. A full length clone was obtained by screening human liver cDNA library. AQP9 encodes a 295-amino-acid protein with the amino acid sequence identity with AQP3 (48%), AQP7 (45%), and other aquaporins (∼30%), suggesting that AQP3, AQP7, and AQP9 belong to a subfamily of the aquaporin family. Injection of AQP9-cRNA intoXenopusoocytes stimulated the osmotic water permeability 7- folds with a low activation energy (4.2 kcal/mol) which was inhibited by 0.3 mM mercury chloride by 48 %. AQP9 also facilitated urea transport 4-folds. However, in contrast to AQP3 and AQP7, AQP9 did not stimulate the glycerol permeability, suggesting a unique permeability character. Northern blot analysis revealed the high expression of 3.5-kb messages in peripheral leukocytes ⪢ liver > lung = spleen, but not in thymus. The possible role of AQP9 in the immunological function of leukocytes is intriguing and the identification of AQP9 with unique permeability profile may expand our understanding of water and small solute transport in the body.
Sei Sasaki - One of the best experts on this subject based on the ideXlab platform.
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Aquaporin 3 is induced in rat alveolar epithelium after birth
Iubmb Life, 1998Co-Authors: Nobuyuki Koyama, Masahiko Ichioka, Naohiko Inase, Michiko Tanaka, Sei Sasaki, Fumiaki MarumoAbstract:Aquaporin (AQP) is the water channel protein associated with water-permeability, in which AQP1, AQP3, AQP4, and AQP5, are expressed in respiratory organs. Because water filling the fetal lung has to be absorbed after birth, aquaporins are postulated to contribute to this water reabsorption. To examine the potential role of AQP3 around birth, we studied mRNA expression and localization of AQP3 in fetal and postnatal rat lung. AQP3 mRNA was most prominently expressed in rat lung on the day of birth, began to decrease on the 2nd day after birth, and was not observed on the 4th day and later. In situ hybridization demonstrated that AQP3 mRNA was expressed in alveolar epithelium. The expression of AQP3 mRNA may influence water reabsorption of the perinatal rat lung.
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Cloning and functional expression of a new aquaporin (AQP9) abundantly expressed in the peripheral leukocytes permeable to water and urea, but not to glycerol.
Biochemical and biophysical research communications, 1998Co-Authors: Kenichi Ishibashi, Fumiaki Marumo, Michio Kuwahara, Yujiro Tanaka, Sei SasakiAbstract:A new member (AQP9) of the aquaporin family was identified from human leukocytes by homology cloning using PCR. A full length clone was obtained by screening human liver cDNA library. AQP9 encodes a 295-amino-acid protein with the amino acid sequence identity with AQP3 (48%), AQP7 (45%), and other aquaporins (approximately 30%), suggesting that AQP3, AQP7, and AQP9 belong to a subfamily of the aquaporin family. Injection of AQP9-cRNA into Xenopus oocytes stimulated the osmotic water permeability 7-folds with a low activation energy (4.2 kcal/mol) which was inhibited by 0.3 mM mercury chloride by 48%. AQP9 also facilitated urea transport 4-folds. However, in contrast to AQP3 and AQP7, AQP9 did not stimulate the glycerol permeability, suggesting a unique permeability character. Northern blot analysis revealed the high expression of 3.5-kb messages in peripheral leukocytes >> liver > lung = spleen, but not in thymus. The possible role of AQP9 in the immunological function of leukocytes is intriguing and the identification of AQP9 with unique permeability profile may expand our understanding of water and small solute transport in the body.
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cloning and functional expression of a new aquaporin AQP9 abundantly expressed in the peripheral leukocytes permeable to water and urea but not to glycerol
Biochemical and Biophysical Research Communications, 1998Co-Authors: Kenichi Ishibashi, Fumiaki Marumo, Michio Kuwahara, Yujiro Tanaka, Sei SasakiAbstract:Abstract A new member (AQP9) of the aquaporin family was identified from human leukocytes by homology cloning using PCR. A full length clone was obtained by screening human liver cDNA library. AQP9 encodes a 295-amino-acid protein with the amino acid sequence identity with AQP3 (48%), AQP7 (45%), and other aquaporins (∼30%), suggesting that AQP3, AQP7, and AQP9 belong to a subfamily of the aquaporin family. Injection of AQP9-cRNA intoXenopusoocytes stimulated the osmotic water permeability 7- folds with a low activation energy (4.2 kcal/mol) which was inhibited by 0.3 mM mercury chloride by 48 %. AQP9 also facilitated urea transport 4-folds. However, in contrast to AQP3 and AQP7, AQP9 did not stimulate the glycerol permeability, suggesting a unique permeability character. Northern blot analysis revealed the high expression of 3.5-kb messages in peripheral leukocytes ⪢ liver > lung = spleen, but not in thymus. The possible role of AQP9 in the immunological function of leukocytes is intriguing and the identification of AQP9 with unique permeability profile may expand our understanding of water and small solute transport in the body.
Joan Vendrell - One of the best experts on this subject based on the ideXlab platform.
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Gene expression of paired abdominal adipose AQP7 and liver AQP9 in patients with morbid obesity: relationship with glucose abnormalities.
Metabolism: clinical and experimental, 2009Co-Authors: Merce Miranda, Victoria Ceperuelo-mallafré, Albert Lecube, Cristina Hernandez, Matilde R. Chacón, José Manuel Fort, Lluis Gallart, Juan Antonio Baena-fustegueras, Rafael Simó, Joan VendrellAbstract:The trafficking of glycerol from adipose and hepatic tissue is mainly mediated by 2 aquaporin channel proteins: AQP7 and AQP9, respectively. In rodents, both aquaporins were found to act in a coordinated manner. The aim was to study the relationship between adipose AQP7 and hepatic AQP9 messenger RNA expression and the presence of glucose abnormalities simultaneously in morbid obesity. Adipose tissue (subcutaneous [SAT] and visceral [VAT]) and liver biopsies from the same patient were obtained during bariatric surgery in 30 (21 male and 9 female) morbidly obese subjects. Real-time quantification of AQP7 in SAT and VAT and hepatic AQP9 gene expression were performed. A 75-g oral glucose tolerance test was performed in all subjects. The homeostasis model assessment of insulin resistance and lipidic profile were also determined. Visceral adipose tissue AQP7 expression levels were significantly higher than SAT AQP7 (P = .009). Subcutaneous adipose tissue AQP7 positively correlated with both VAT AQP7 and hepatic AQP9 messenger RNA expression (r = 0.44, P = .013 and r = 0.45, P = .012, respectively). The correlation between SAT AQP7 and liver AQP9 was stronger in intolerant and type 2 diabetes mellitus subjects (r = 0.602, P = .011). We have found no differences in compartmental AQP7 adipose tissue distribution or AQP9 hepatic gene expression according to glucose tolerance classification. The present study provides, for the first time, evidence of coordinated regulation between adipose aquaglyceroporins, with a greater expression found in visceral fat, and between subcutaneous adipose AQP7 and hepatic AQP9 gene expression within the context of human morbid obesity.
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Influence of Morbid Obesity and Insulin Resistance on Gene Expression Levels of AQP7 in Visceral Adipose Tissue and AQP9 in Liver
Obesity surgery, 2008Co-Authors: Victoria Catalán, Javier Gómez-ambrosi, Carlos Pastor, Fernando Rotellar, Camilo Silva, Amaia Rodríguez, María J. Gil, Javier A. Cienfuegos, Javier Salvador, Joan VendrellAbstract:Glycerol production and its efflux from adipocytes to the liver are key to modulate lipid and glucose homeostasis. Aquaporin 7 (AQP7) is an aquaglyceroporin that acts as the adipose glycerol channel, whereas aquaporin 9 (AQP9) is the specific channel operating in the liver. The aim of the present work was to evaluate the effect of obesity and type 2 diabetes mellitus (T2DM) on gene expression levels of AQP7 in visceral adipose tissue (VAT) and AQP9 in liver. VAT and liver biopsies obtained from 20 women were used in the study. Patients were classified as lean or obese with the last group being further subclassified as normoglycemic (NG), patients with impaired glucose tolerance (IGT), or with T2DM. Anthropometric measurements as well as circulating metabolites, hormones, and adipokines were determined. Real-time polymerase chain reaction analyses were performed to quantify transcript levels of AQP7 in VAT and AQP9 in the liver. Gene expression levels of AQP7 in VAT showed a tendency toward an increase (P = 0.065) in obese patients (both NG and T2DM) compared to lean subjects. AQP9 showed a significant downregulation in the hepatic biopsies obtained from obese T2DM patients compared to obese NG and IGT patients (P = 0.028). The tendency toward an elevation of mRNA expression of VAT AQP7 in obesity together with the decreased hepatic AQP9 expression observed in obese T2DM subjects suggests a potential role in facilitating glycerol release from adipose tissue and reducing glycerol entry into hepatocytes in obesity and T2DM, respectively.
Jennifer Southgate - One of the best experts on this subject based on the ideXlab platform.
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Nocturnal enuresis—investigating the possible role of water transfer across the urothelium by looking for the presence of vasopressin receptors and aquaporins in urothelium
Archives of Disease in Childhood, 2010Co-Authors: Peter Rubenwolf, P Holland, Nikolaos T. Georgopoulos, Lisa A. Clements, Sally Feather, David Terence Thomas, Jennifer SouthgateAbstract:Aims To test the hypothesis that vasopressin-sensitive aquaporin 2 (AQP2) may be present in the human urothelium and contribute towards obtaining night time continence. Background In studies comparing dry and wet nights in children with enuresis it was hypothesised that there may be water transfer across the urothelium overnight resulting in an increase in urine concentration and a reduction in urine volume. The authors postulated that human urothelium would have to express the vasopressin receptor and AQP2. Methods Using previously evaluated techniques, human urothelium was isolated and used to prepare messenger RNA, perform immunohistological studies and to establish finite NHU cell lines. All samples were then studied for expression of vasopressin receptor and aquaporins 0–12. Results Native and cultured urothelia were negative for vasopressin receptor and AQP2 transcripts, whereas transcripts for aquaporins 3, 4, 7, 9 and 11 were detected. Immunohistochemistry revealed human urothelium to be intensely positive for AQP3 in the basal and intermediate layers of the urothelium, localising to intercellular borders. AQP 4 and 7 showed less intense cytoplasmic expression throughout the urothelium. No immunoreactivity was found for AQP 9. Conclusion The original hypothesis that water transfer might occur across human urothelium due to the presence of vasopressin-sensitive AQP2 is incorrect. The detection of AQP 3 and 4 raises the possibility that water and urea transfer may occur across the urothelium. However, it is yet to be determined whether these proteins contribute to urinary continence mechanisms.
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Expression and localisation of aquaporin water channels in human urothelium in situ and in vitro.
European Urology, 2008Co-Authors: Peter Rubenwolf, Nikolaos T. Georgopoulos, Lisa A. Clements, Sally Feather, Philip Holland, David F.m. Thomas, Jennifer SouthgateAbstract:Abstract Background Urothelium is generally considered to be impermeable to water and constituents of urine. The possibility that human urothelium expresses aquaporin (AQP) water channels as the basis for water and solute transport has not previously been investigated. Objective To investigate the expression of AQP water channels by human urothelium in situ, in proliferating urothelial cell cultures and in differentiated tissue constructs. Design, setting, and participants AQP expression by human urothelium in situ and cultured urothelial cells was assessed by reverse transcriptase–polymerase chain reaction (RT-PCR) and immunolabelling. Expression screening was carried out on samples of freshly isolated urothelia from multiple surgical (bladder and ureteric) specimens and on proliferating and differentiated normal human urothelial (NHU) cells in culture. Urothelial tissue constructs were established and investigated for expression of urothelial differentiation markers and AQPs. Measurements Qualitative study. Results and limitations Transcripts for AQP3, AQP4, AQP7, AQP9, and AQP11 were expressed consistently by freshly isolated urothelia as well as by cultured NHU cells. AQP0, AQP1, AQP2, AQP5, AQP6, AQP8, AQP10, and AQP12 were not expressed. Immunochemistry confirmed expression of AQP3, AQP4, AQP7, and AQP9 at the protein level. AQP3 was shown to be intensely expressed at cell borders in the basal and intermediate layers in both urothelium in situ and differentiated tissue constructs in vitro. Conclusions This is the first study to demonstrate that AQPs are expressed by human urothelium, suggesting a potential role in transurothelial water and solute transport. Our findings challenge the traditional concept of the urinary tract as an impermeable transit and storage unit and provide a versatile platform for further investigations into the biological and clinical relevance of AQPs in human urothelium.
Amaia Rodríguez - One of the best experts on this subject based on the ideXlab platform.
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Sexual Dimorphism of Adipose and Hepatic Aquaglyceroporins in Health and Metabolic Disorders
Frontiers in Endocrinology, 2015Co-Authors: Amaia Rodríguez, Gema Frühbeck, Raúl A. Marinelli, Angela Tesse, Giuseppe CalamitaAbstract:Gender differences in the relative risk of developing metabolic complications, such as insulin resistance or non-alcoholic fatty liver disease (NAFLD), have been reported. The deregulation of glycerol metabolism partly contributes to the onset of these metabolic diseases, since glycerol constitutes a key substrate for the synthesis of triacylglycerols (TAGs) as well as for hepatic gluconeogenesis. The present mini-review covers the sex−related differences in glycerol metabolism and aquaglyceroporins (AQPs) and its impact in the control of adipose and hepatic fat accumulation as well as in whole-body glucose homeostasis. Plasma glycerol concentrations are increased in women compared to men probably due to the higher lipolytic rate and larger AQP7 amounts in visceral fat as well as the well-known sexual dimorphism in fat mass with women showing higher adiposity. AQP9 represents the primary route for glycerol uptake in hepatocytes, where glycerol is converted by the glycerol-kinase enzyme into glycerol-3-phosphate, a key substrate for de novo synthesis of glucose and TAG. In spite of showing similar hepatic AQP9 protein, women exhibit lower hepatocyte glycerol permeability than men, which might contribute to their lower prevalence of insulin resistance and NAFLD.
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Influence of Morbid Obesity and Insulin Resistance on Gene Expression Levels of AQP7 in Visceral Adipose Tissue and AQP9 in Liver
Obesity surgery, 2008Co-Authors: Victoria Catalán, Javier Gómez-ambrosi, Carlos Pastor, Fernando Rotellar, Camilo Silva, Amaia Rodríguez, María J. Gil, Javier A. Cienfuegos, Javier Salvador, Joan VendrellAbstract:Glycerol production and its efflux from adipocytes to the liver are key to modulate lipid and glucose homeostasis. Aquaporin 7 (AQP7) is an aquaglyceroporin that acts as the adipose glycerol channel, whereas aquaporin 9 (AQP9) is the specific channel operating in the liver. The aim of the present work was to evaluate the effect of obesity and type 2 diabetes mellitus (T2DM) on gene expression levels of AQP7 in visceral adipose tissue (VAT) and AQP9 in liver. VAT and liver biopsies obtained from 20 women were used in the study. Patients were classified as lean or obese with the last group being further subclassified as normoglycemic (NG), patients with impaired glucose tolerance (IGT), or with T2DM. Anthropometric measurements as well as circulating metabolites, hormones, and adipokines were determined. Real-time polymerase chain reaction analyses were performed to quantify transcript levels of AQP7 in VAT and AQP9 in the liver. Gene expression levels of AQP7 in VAT showed a tendency toward an increase (P = 0.065) in obese patients (both NG and T2DM) compared to lean subjects. AQP9 showed a significant downregulation in the hepatic biopsies obtained from obese T2DM patients compared to obese NG and IGT patients (P = 0.028). The tendency toward an elevation of mRNA expression of VAT AQP7 in obesity together with the decreased hepatic AQP9 expression observed in obese T2DM subjects suggests a potential role in facilitating glycerol release from adipose tissue and reducing glycerol entry into hepatocytes in obesity and T2DM, respectively.
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influence of morbid obesity and insulin resistance on gene expression levels of aqp7 in visceral adipose tissue and AQP9 in liver
Obesity Surgery, 2008Co-Authors: Victoria Catalán, Carlos Pastor, Fernando Rotellar, Camilo Silva, Amaia Rodríguez, Javier Gomezambrosi, María J. GilAbstract:Background Glycerol production and its efflux from adipocytes to the liver are key to modulate lipid and glucose homeostasis. Aquaporin 7 (AQP7) is an aquaglyceroporin that acts as the adipose glycerol channel, whereas aquaporin 9 (AQP9) is the specific channel operating in the liver. The aim of the present work was to evaluate the effect of obesity and type 2 diabetes mellitus (T2DM) on gene expression levels of AQP7 in visceral adipose tissue (VAT) and AQP9 in liver.