Cloning of a New Aquaporin (AQP10) Abundantly Expressed in Duodenum and Jejunum

Hatakeyama, Satoru; Yoshida, Yutaka; Tani, Tadaaki; Koyama, Yu; Nihei, Kouei; Ohshiro, Kazufumi; Kamiie, Junichi; Yaoita, Eishin; Suda, Takeyasu; Hatakeyama, Katsuyoshi; Yamamoto, Tadashi

doi:10.1006/bbrc.2001.5661

Cited by 139 publications

(115 citation statements)

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“…When assayed in Xenopus oocytes, hAQP10 was reported to be primarily a glycerol transporter with limited water transport (2,3). In contrast, our work in proteoliposomes clearly shows a high intrinsic water transport activity for hAQP10 that was comparable with that obtained for other pure water transporters such as hAQP1; Pf ϭ 9.1 Ϯ 0.4 (control: 3.1 Ϯ 0.01) (25) and hAQP4; Pf ϭ 7.5 Ϯ 0.03 (control: 2.4 Ϯ 0.01).…”

Section: Discussionmentioning

confidence: 99%

“…Aquaporins (AQPs) 2 primarily facilitate the transport of water across biological membranes, where water movements are driven by hypertonic or hypotonic conditions. AQPs consist of six transmembrane domains and five connecting loops ( Fig.…”

mentioning

confidence: 99%

“…Human aquaporin10 (hAQP10) was first identified in a human jejunum cDNA library and was observed to have 264 amino acids and dual copies of the aquaporin signature NPA motifs, confirming it as a member of the aquaporin family located in the small intestine (2). From homology studies the protein had been classified as an aquaglyceroporin, but surprisingly it did not show any glycerol or urea transport and only a low permeability to water in Xenopus oocytes (2).…”

mentioning

confidence: 99%

“…From homology studies the protein had been classified as an aquaglyceroporin, but surprisingly it did not show any glycerol or urea transport and only a low permeability to water in Xenopus oocytes (2). Shortly thereafter, an independent study identified a 301-amino acid protein with a different sixth transmembrane domain which transported both glycerol and water in Xenopus oocytes (3).…”

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confidence: 99%

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Glycosylation Increases the Thermostability of Human Aquaporin 10 Protein

Öberg

Sjöhamn

Fischer

et al. 2011

Journal of Biological Chemistry

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Human aquaporin10 (hAQP10) is a transmembrane facilitator of both water and glycerol transport in the small intestine. This aquaglyceroporin is located in the apical membrane of enterocytes and is believed to contribute to the passage of water and glycerol through these intestinal absorptive cells. Here we overproduced hAQP10 in the yeast Pichia pastoris and observed that the protein is glycosylated at Asn-133 in the extracellular loop C. This finding confirms one of three predicted glycosylation sites for hAQP10, and its glycosylation is unique for the human aquaporins overproduced in this host. Nonglycosylated protein was isolated using both glycan affinity chromatography and through mutating asparagine 133 to a glutamine. All three forms of hAQP10 where found to facilitate the transport of water, glycerol, erythritol, and xylitol, and glycosylation had little effect on functionality. In contrast, glycosylated hAQP10 showed increased thermostability of 3-6°C compared with the nonglycosylated protein, suggesting a stabilizing effect of the N-linked glycan. Because only one third of hAQP10 was glycosylated yet the thermostability titration was mono-modal, we suggest that the presence of at least one glycosylated protein within each tetramer is sufficient to convey an enhanced structural stability to the remaining hAQP10 protomers of the tetramer.Intrinsic membrane proteins are essential for the selective transport of molecules in and out of cells and hence the regulation of their concentration within the cell. Aquaporins (AQPs) 2 primarily facilitate the transport of water across biological membranes, where water movements are driven by hypertonic or hypotonic conditions. AQPs consist of six transmembrane domains and five connecting loops ( Fig. 1) with both termini located on the intracellular side of the membrane. Aquaporins also contain two half-helices in loops B and E which align to form a pseudo-transmembrane helix, the focus of which contains the signature motif asparagine-proline-alanine (NPA). In vivo the protein assemblies into homotetramers, and each monomer functions as a water channel. Thirteen aquaporin family members exist within humans, with varying tissue distribution and substrate specificity (1). Two major subclasses have been identified: the orthodox aquaporins (hAQP0, hAQP1, hAQP2, hAQP4, hAQP5, hAQP6, and hAQP8) mainly facilitating the movement of water, and the aquaglyceroporins (hAQP3, hAQP7, hAQP9, and hAQP10) which facilitate both the transport of water and of other small solutes.Human aquaporin10 (hAQP10) was first identified in a human jejunum cDNA library and was observed to have 264 amino acids and dual copies of the aquaporin signature NPA motifs, confirming it as a member of the aquaporin family located in the small intestine (2). From homology studies the protein had been classified as an aquaglyceroporin, but surprisingly it did not show any glycerol or urea transport and only a low permeability to water in Xenopus oocytes (2). Shortly thereafter, an independent study identified...

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Section: Discussionmentioning

confidence: 99%

mentioning

confidence: 99%

mentioning

confidence: 99%

mentioning

confidence: 99%

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Glycosylation Increases the Thermostability of Human Aquaporin 10 Protein

Öberg

Sjöhamn

Fischer

et al. 2011

Journal of Biological Chemistry

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“…There are currently 13 known types of AQPs in humans, AQP0 through AQP12, which are expressed in a variety of tissues (15). Several AQPs are expressed in the intestinal tract, and at least the following eight types are known to exist there: AQP1, AQP2, AQP3, AQP4, AQP7, AQP8, AQP9, and AQP10 (5,7,17,23). The main AQPs expressed in the colon are AQP1, AQP2, AQP3, AQP4, and AQP8 (5,16,23).…”

mentioning

confidence: 99%

The laxative effect of bisacodyl is attributable to decreased aquaporin-3 expression in the colon induced by increased PGE₂secretion from macrophages

Ikarashi

Baba

Ushiki

et al. 2011

American Journal of Physiology-Gastrointestinal and Liver Physi

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Ikarashi N, Baba K, Ushiki T, Kon R, Mimura A, Toda T, Ishii M, Ochiai W, Sugiyama K. The laxative effect of bisacodyl is attributable to decreased aquaporin-3 expression in the colon induced by increased PGE 2 secretion from macrophages. Am J Physiol Gastrointest Liver Physiol 301: G887-G895, 2011. First published August 25, 2011; doi:10.1152/ajpgi.00286.2011.-The purpose of this study was to investigate the role of aquaporin3 (AQP3) in the colon in the laxative effect of bisacodyl. After oral administration of bisacodyl to rats, AQP3, macrophages, cyclooxygenase 2 (COX2), and prostaglandin E 2 (PGE2) were examined in the colon. The mechanism by which bisacodyl decreases the expression of AQP3 was examined using HT-29 and Raw264.7 cells. When diarrhea occurred, a significant increase in the expression of PGE 2 and a decrease in AQP3 expression were observed. Immunostaining showed COX2 expression only in macrophages. The PGE 2 concentration increased significantly 30 min after the addition of bisacodyl to Raw264.7 cells. Thirty minutes after PGE 2 addition to HT-29 cells, the AQP3 expression level decreased to 40% of the control. When pretreated with indomethacin, bisacodyl did not induce an increase in the colon PGE 2 level, a decrease in the AQP3 expression level, or diarrhea. The results suggest that bisacodyl may decrease the expression of AQP3 in the colon, which inhibits water transfer from the luminal to the vascular side and leads to a laxative effect. This study also showed that direct activation of colon macrophages by bisacodyl increases the secretion of PGE 2, which acts as a paracrine factor and decreases AQP3 expression in colon mucosal epithelial cells. aquaporin-3; prostaglandin E 2; bisacodyl; cyclooxygenase IN RECENT YEARS, IT HAS BECOME increasingly clear that aquaporins (AQPs), water channels, are involved in water transport in the intestinal tract (20). There are currently 13 known types of AQPs in humans, AQP0 through AQP12, which are expressed in a variety of tissues (15). Several AQPs are expressed in the intestinal tract, and at least the following eight types are known to exist there: AQP1, AQP2, AQP3, AQP4, AQP7, AQP8, AQP9, and AQP10 (5, 7, 17, 23). The main AQPs expressed in the colon are AQP1, AQP2, AQP3, AQP4, and AQP8 (5,16,23). Of these, extensive research has been conducted on AQP3, which is considered to play an important role in the colon, especially regarding water transfer (13, 34). We have found that the administration of the osmotic laxative magnesium sulfate (MgSO 4 ) to rats increases the expression of AQP3 in the colon, and an increase in the expression of AQP3 plays an essential role in the laxative effect of MgSO 4 (11,12).Bisacodyl is classified as a stimulant laxative and is widely used to treat constipation. Bisacodyl increases the production of prostaglandin E 2 (PGE 2 ) in intestinal epithelial cells and inhibits the activity of Na ϩ -K ϩ -ATPase, and, as a result, the osmotic pressure in the intestinal tract increases. It is believed that this increase in osmoti...

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Water exchange across the blood–brain barrier and epilepsy: Review on pathophysiology and neuroimaging

Abdennadher,

Jacobellis,

Václavů

et al. 2024

Epilepsia Open

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The blood–brain barrier (BBB) is a barrier protecting the brain and a milieu of continuous exchanges between blood and brain. There is emerging evidence that the BBB plays a major role in epileptogenesis and drug‐resistant epilepsy, through several mechanisms, such as water homeostasis dysregulation, overexpression of drug transporters, and inflammation. Studies have shown abnormal water homeostasis in epileptic tissue and altered aquaporin‐4 water channel expression in animal epilepsy models. This review focuses on abnormal water exchange in epilepsy and describes recent non‐invasive MRI methods of quantifying water exchange.Plain Language SummaryAbnormal exchange between blood and brain contribute to seizures and epilepsy. The authors describe why correct water balance is necessary for healthy brain functioning and how it is impacted in epilepsy. This review also presents recent MRI methods to measure water exchange in human brain. These measures would improve our understanding of factors leading to seizures.

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Cloning of a New Aquaporin (AQP10) Abundantly Expressed in Duodenum and Jejunum

Cited by 139 publications

References 22 publications

Glycosylation Increases the Thermostability of Human Aquaporin 10 Protein

Glycosylation Increases the Thermostability of Human Aquaporin 10 Protein

The laxative effect of bisacodyl is attributable to decreased aquaporin-3 expression in the colon induced by increased PGE₂secretion from macrophages

Water exchange across the blood–brain barrier and epilepsy: Review on pathophysiology and neuroimaging

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Cloning of a New Aquaporin (AQP10) Abundantly Expressed in Duodenum and Jejunum

Cited by 139 publications

References 22 publications

Glycosylation Increases the Thermostability of Human Aquaporin 10 Protein

Glycosylation Increases the Thermostability of Human Aquaporin 10 Protein

The laxative effect of bisacodyl is attributable to decreased aquaporin-3 expression in the colon induced by increased PGE2secretion from macrophages

Water exchange across the blood–brain barrier and epilepsy: Review on pathophysiology and neuroimaging

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The laxative effect of bisacodyl is attributable to decreased aquaporin-3 expression in the colon induced by increased PGE₂secretion from macrophages