Dataset Information

Relative CO2/NH3 selectivities of AQP1, AQP4, AQP5, AmtB, and RhAG.

ABSTRACT: The water channel aquaporin 1 (AQP1) and certain Rh-family members are permeable to CO(2) and NH(3). Here, we use changes in surface pH (pH(S)) to assess relative CO(2) vs. NH(3) permeability of Xenopus oocytes expressing members of the AQP or Rh family. Exposed to CO(2) or NH(3), AQP1 oocytes exhibit a greater maximal magnitude of pH(S) change (DeltapH(S)) compared with day-matched controls injected with H(2)O or with RNA encoding SGLT1, NKCC2, or PepT1. With CO(2), AQP1 oocytes also have faster time constants for pH(S) relaxation (tau(pHs)). Thus, AQP1, but not the other proteins, conduct CO(2) and NH(3). Oocytes expressing rat AQP4, rat AQP5, human RhAG, or the bacterial Rh homolog AmtB also exhibit greater DeltapH(S)(CO(2)) and faster tau(pHs) compared with controls. Oocytes expressing AmtB and RhAG, but not AQP4 or AQP5, exhibit greater DeltapH(S)(NH(3)) values. Only AQPs exhibited significant osmotic water permeability (P(f)). We computed channel-dependent (*) DeltapH(S) or P(f) by subtracting values for H(2)O oocytes from those of channel-expressing oocytes. For the ratio DeltapH(S)(CO(2))*/P(f)*, the sequence was AQP5 > AQP1 congruent with AQP4. For DeltapH(S)(CO(2))*/DeltapH(S)(NH(3))*, the sequence was AQP4 congruent with AQP5 > AQP1 > AmtB > RhAG. Thus, each channel exhibits a characteristic ratio for indices of CO(2) vs. NH(3) permeability, demonstrating that, like ion channels, gas channels can exhibit selectivity.

SUBMITTER: Musa-Aziz R

PROVIDER: S-EPMC2664022 | biostudies-literature | 2009 Mar

REPOSITORIES: biostudies-literature

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Relative CO2/NH3 selectivities of AQP1, AQP4, AQP5, AmtB, and RhAG.

Musa-Aziz Raif R Chen Li-Ming LM Pelletier Marc F MF Boron Walter F WF

Proceedings of the National Academy of Sciences of the United States of America 20090309 13

The water channel aquaporin 1 (AQP1) and certain Rh-family members are permeable to CO(2) and NH(3). Here, we use changes in surface pH (pH(S)) to assess relative CO(2) vs. NH(3) permeability of Xenopus oocytes expressing members of the AQP or Rh family. Exposed to CO(2) or NH(3), AQP1 oocytes exhibit a greater maximal magnitude of pH(S) change (DeltapH(S)) compared with day-matched controls injected with H(2)O or with RNA encoding SGLT1, NKCC2, or PepT1. With CO(2), AQP1 oocytes also have faste ...[more]

PMID: 19273840

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Project description:BackgroundIncreasing evidence has demonstrated aquaporins (AQPs) to be critical players in carcinogenesis. Here, we aimed to explore the role of hydropenia in the progression of bladder cancer (BCa), as well as to assess the expression of AQP1, AQP3, and AQP4 in bladder tissues from hydropenic and N-methyl-N-nitrosourea (MNU)-treated rats.MethodsAn orthotopic BCa model was induced by administering Sprague Dawley rats with MNU. A hydropenic rat model was established by administrating rats with 2/3 of the amount of water given to the control group. At week 8, the rats were sacrificed and their bladder tissues were collected. Then, pathological alterations in the rat bladders were assessed by hematoxylin and eosin staining. The RNA and protein expression levels of AQP1, AQP3, and AQP4 were determined by using qRT-PCR and western blot assays.ResultsAll of the rats (100%) administrated with MNU developed tumors, of which 5 were large (diameter, 0.5-1.0 cm), 10 were medium (diameter, 0.2-0.5 cm), and 5 were small (diameter, <0.2 cm) in size. The tumors were nodular and cauliflower shaped, with multiple satellite focus, and were accompanied by bleeding, ulcers, stones, and residual urine. Hematoxylin and eosin staining revealed that the bladder mucosa was incomplete, with a large amount of necrotic tissue and obvious leukocytic infiltration. The tumor volume in the MNU + hydropenia group was significantly larger than that in the MNU group. Noticeably, hydropenia exacerbated pathological changes induced by MNU administration. QRT-PCR and western blot analysis revealed that the MNU group, hydropenia group, and MNU + hydropenia group had significantly increased levels of AQP1, AQP3, and AQP4 compared to the control group, with the most dramatic increase seen in the MNU + hydropenia group.ConclusionsHydropenia exacerbates pathological alterations induced by MNU in rats with orthotopic BCa by increasing the expression levels of AQP1, AQP3, and AQP4. This study reveals a possible mechanism of the occurrence of BCa.

Dataset Information

Relative CO2/NH3 selectivities of AQP1, AQP4, AQP5, AmtB, and RhAG.

Publications

Relative CO2/NH3 selectivities of AQP1, AQP4, AQP5, AmtB, and RhAG.

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