The pH sensitivity of Aqp0 channels in tetraploid and diploid teleosts

Water homeostasis and the structural integrity of the vertebrate lens is partially mediated by AQP0 channels. Emerging evidence indicates that external pH may be involved in channel gating. Here we show that a tetraploid teleost, the Atlantic salmon, retains 4 aqp0 genes (aqp0a1, -0a2, -0b1, and -0b...

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Bibliographic Details
Published in:The FASEB Journal
Main Authors: Chauvigné, Francois, Zapater, Cinta, Stavang, Jon Anders, Taranger, Geir Lasse, Cerdà, Joan, Finn, Roderick Nigel
Format: Article in Journal/Newspaper
Language:English
Published: Federation of American Society of Experimental Biology 2015
Subjects:
aquaporin
water transport
permeability lens
cataract
VDP::Matematikk og naturvitenskap: 400::Zoologiske og botaniske fag: 480::Marinbiologi: 497
VDP::Mathematics and natural scienses: 400::Zoology and botany: 480::Marine biology: 497
Finn
Atlantic salmon
Online Access:http://hdl.handle.net/1956/11046
https://doi.org/10.1096/fj.14-267625
Description
Summary:Water homeostasis and the structural integrity of the vertebrate lens is partially mediated by AQP0 channels. Emerging evidence indicates that external pH may be involved in channel gating. Here we show that a tetraploid teleost, the Atlantic salmon, retains 4 aqp0 genes (aqp0a1, -0a2, -0b1, and -0b2), which are highly, but not exclusively, expressed in the lens. Functional characterization reveals that, although each paralog permeates water efficiently, the permeability is respectively shifted to the neutral, alkaline, or acidic pH in Aqp0a1, -0a2, and -0b1, whereas that of Aqp0b2 is not regulated by external pH. Mutagenesis studies demonstrate that Ser38, His39, and His40 residues in the extracellular transmembrane domain of α-helix 2 facing the water pore are critical for the pH modulation of water transport. To validate these findings, we show that both zebrafish Aqp0a and -0b are functional water channels with respective pH sensitivities toward alkaline or acid pH ranges and that an N-terminal allelic variant (Ser19) of Aqp0b exists that abolishes water transport in Xenopus laevis oocytes. The data suggest that the alkaline pH sensitivity is a conserved trait in teleost Aqp0 a-type channels, whereas mammalian AQP0 and some teleost Aqp0 b-type channels display an acidic pH permeation preference.—Chauvigné, F., Zapater, C., Stavang, J. A., Taranger, G. L., Cerdà, J., Finn, R. N. The pH sensitivity of Aqp0 channels in tetraploid and diploid teleosts. publishedVersion

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