Anion exchanger 1b, but not sodium-bicarbonate cotransporter 1b, plays a role in transport functions of zebrafish H+-ATPase-rich cells.
Similar to mammalian proximal tubular cells, H(+)-ATPase rich (HR) cells in zebrafish skin and gills are also responsible for Na(+) uptake and acid secretion functions. However, the basolateral transport pathways in HR cells are still unclear. In the present study, we tested the hypothesis if there are specific slc4 members involved in basolateral ion transport pathways in HR cells. Fourteen isoforms were identified in the zebrafish(z) slc4 family, and the full-length cDNAs of two novel isoforms, zslc4a1b (anion exchanger, zAE1b) and zslc4a4b (Na(+)/HCO(3)(-) cotransporter, zNBCe1b), were sequenced. mRNA signals of zslc4a1b and zslc4a4b were mainly detected in certain groups of ionocytes in zebrafish skin/gills. Further double immunocytochemistry or in situ hybridization demonstrated that zAE1b, but not zNBCe1b, was localized to basolateral membranes of HR cells. Acclimation to low-Na(+) or acidic environments stimulated the mRNA expression of zslc4a1b in zebrafish gills, and loss-of-function of zslc4a1b with specific morpholinos caused significant decreases in both the whole body Na(+) content and the skin H(+) activity in the morphants. On the basis of these results, it was concluded that zAE1b, but not zNBCe1b, is involved in the basolateral transport pathways in Na(+) uptake/acid secretion mechanisms in zebrafish HR cells.
Institute of Cellular and Organismic Biology, Academia Sinica, Nankang, Taipei, Taiwan 11529, Republic of China.
Yi-Chun
YC
Lee
Jia-Jiun
JJ
Yan
Shelly A
SA
Cruz
Jiun-Lin
JL
Horng
Pung-Pung
PP
Hwang
D000595:Amino Acid Sequence; D000818:Animals; D001457:Anion Exchange Protein 1, Erythrocyte / Q000235:genetics / Q000378:metabolism*; D017136:Ion Transport; D008969:Molecular Sequence Data; D009154:Mutation; D006180:Proton-Translocating ATPases / Q000378:metabolism*; D012867:Skin / Q000378:metabolism*; D012964:Sodium / Q000032:analysis / Q000378:metabolism; D027982:Sodium-Bicarbonate Symporters / Q000235:genetics / Q000378:metabolism*; D015027:Zebrafish / Q000235:genetics / Q000378:metabolism*; D029961:Zebrafish Proteins / Q000235:genetics / Q000378:metabolism*
D001457:Anion Exchange Protein 1, Erythrocyte; D027982:Sodium-Bicarbonate Symporters; D029961:Zebrafish Proteins; C545212:slc4a4a protein, zebrafish; D012964:Sodium; D006180:Proton-Translocating ATPases