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Generation and Phenotype of a Transgenic Knockout Mouse Lacking the Urea Transporters UT‐A2 and UT‐B
Author(s) -
Yang Baoxue,
Lei Tianluo,
Bankir Lise,
Zhou Hong
Publication year - 2010
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.24.1_supplement.1024.22
Subject(s) - microbiology and biotechnology , western blot , knockout mouse , gene , biology , chemistry , genetically modified mouse , transgene , biochemistry
UT‐A2 and UT‐B are two distinct urea‐selective channels, coded by two different genes on the same chromosome. UT‐A2 is mainly expressed in the thin descending limb of Henle's loop, and UT‐B in descending vasa recta and red blood cells. We generated mice with simultaneous knockout (KO) of these two genes (DbleKO). A targeting vector for homologous recombination was constructed using a mouse UT‐A genomic fragment in which UT‐A2 promoter sequence was deleted. UT‐A gene targeting was performed on UT‐B gene knock‐out embryonic stem cells. The [−/−] mice lacked detectable UT‐A2 and UT‐B proteins by Western blot and immunofluorescence. Survival and growth of DbleKO were not different from that in wild‐type mice (WT). Daily urine output was 2.63 ± 0.13 ml in DbleKO, which was higher than that in WT (2.01 ± 0.17, p < 0.01) and lower than that in UT‐B KO (3.65 ± 0.16, p < 0.01). Urine osmolality (U osm , in mosm/kg H 2 O) in DbleKO (2176 ± 181) was between those in UT‐B KO (1697 ± 164, p < 0.01) and WT (2524 ± 193, p < 0.01). After 18 h water deprivation, U osm was 2976 ± 197 in DbleKO, 2375 ± 228 in UT‐B KO and 4281 ± 257 in WT. These results show that UT‐A2 deletion in UT‐B KO mice attenuates the urine concentrating defect caused by UT‐B deletion. They suggest that UT‐A2 may allow an exit of urea from the thin limbs rather than an entry of urea, as usually assumed, and thus challenge established intrarenal urea recycling mechanism.