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The urea transporter UT‐A1 is phosphorylated at serines 486 and 499 downstream of cyclic AMP production
Author(s) -
Thai Tiffany L,
Gumina Diane L,
Ilori Titilayo O,
Klein Janet D,
Blount Mitsi A,
Sands Jeff M
Publication year - 2012
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.26.1_supplement.885.11
Subject(s) - forskolin , phosphorylation , adenylyl cyclase , chemistry , medicine , endocrinology , biology , stimulation , biochemistry
Urea permeability in the renal inner medullary collecting duct (IMCD) is important for urine concentration. Membrane insertion of the urea transporter UT‐A1 is regulated downstream of vasopressin (AVP)‐induced production of cyclic AMP (cAMP). UT‐A1 is phosphorylated downstream of AVP at two sites: serines 486 and 499, both of which are required for membrane insertion. We tested the hypothesis that cAMP production is required for phosphorylation of UT‐A1 at serines 486 and 499. Mouse IMCD3 cells stably transfected with UT‐A1 were treated with the adenylyl cyclase agonist forskolin and levels of phosphorylation of S486 and 499 were tested by western blot. Forskolin‐induced phosphorylation of both serines was observed with maximum effect at 5 min. Rats were fed a diet of 33% lithium for 7 days as a model of long‐term adenylyl cyclase inhibition. Kidneys were harvested and inner medullas were treated with forskolin and analyzed for total UT‐A1 as well as phosphorylation of 486 and 499. Baseline levels of UT‐A1 and phosphorylation at both sites was reduced. Whereas a strong increase in S486 and S499 phosphorylation was observed in response to forskolin in control rats, little response was seen in animals fed lithium. Overall, we conclude that cAMP produced by adenylyl cyclase results in phosphorylation of UT‐A1 serines 486 and 499 in the inner medulla. This work was supported by NIH grants T32 DK007771 and RO1 DK41707.