Vasopressin regulation of multisite phosphorylation of UT-A1 in the inner medullary collecting duct.
Am J Physiol Renal Physiol
; 308(1): F49-55, 2015 Jan 01.
Article
em En
| MEDLINE
| ID: mdl-25377918
ABSTRACT
Vasopressin signaling is critical for the regulation of urea transport in the inner medullary collecting duct (IMCD). Increased urea permeability is driven by a vasopressin-mediated elevation of cAMP that results in the direct phosphorylation of urea transporter (UT)-A1. The identification of cAMP-sensitive phosphorylation sites, Ser(486) and Ser(499), in the rat UT-A1 sequence was the first step in understanding the mechanism of vasopressin action on the phosphorylation-dependent modulation of urea transport. To investigate the significance of multisite phosphorylation of UT-A1 in response to elevated cAMP, we used highly specific and sensitive phosphosite antibodies to Ser(486) and Ser(499) to determine cAMP action at each phosphorylation site. We found that phosphorylation at both sites was rapid and sustained. Furthermore, the rate of phosphorylation of the two sites was similar in both mIMCD3 cells and rat inner medullary tissue. UT-A1 localized to the apical membrane in response to vasopressin was phosphorylated at Ser(486) and Ser(499). We confirmed that elevated cAMP resulted in increased phosphorylation of both sites by PKA but not through the vasopressin-sensitive exchange protein activated by cAMP pathway. These results elucidate the multisite phosphorylation of UT-A1 in response to cAMP, thus providing the beginning of understanding the intracellular factors underlying vasopressin stimulation of urea transport in the IMCD.
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Base de dados:
MEDLINE
Assunto principal:
Proteínas de Membrana Transportadoras
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Vasopressinas
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Proteínas Quinases Dependentes de AMP Cíclico
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Túbulos Renais Coletores
Tipo de estudo:
Prognostic_studies
Limite:
Animals
Idioma:
En
Ano de publicação:
2015
Tipo de documento:
Article