Assuntos
Proteínas de Ancoragem à Quinase A/antagonistas & inibidores , Proteínas Quinases Dependentes de AMP Cíclico/antagonistas & inibidores , Inibidores de Proteínas Quinases/química , Piridinas/química , Proteínas de Ancoragem à Quinase A/metabolismo , Sítios de Ligação , Ligação Competitiva , Proteínas Quinases Dependentes de AMP Cíclico/metabolismo , Células HEK293 , Humanos , Simulação de Acoplamento Molecular , Domínios e Motivos de Interação entre Proteínas , Inibidores de Proteínas Quinases/síntese química , Inibidores de Proteínas Quinases/metabolismo , Estrutura Terciária de Proteína , Piridinas/síntese química , Piridinas/metabolismoRESUMO
In the principal cells of the renal collecting duct, arginine vasopressin (AVP) stimulates the synthesis of cAMP, leading to signaling events that culminate in the phosphorylation of aquaporin-2 water channels and their redistribution from intracellular domains to the plasma membrane via vesicular trafficking. The molecular mechanisms that control aquaporin-2 trafficking and the consequent water reabsorption, however, are not completely understood. Here, we used a cell-based assay and automated immunofluorescence microscopy to screen 17,700 small molecules for inhibitors of the cAMP-dependent redistribution of aquaporin-2. This approach identified 17 inhibitors, including 4-acetyldiphyllin, a selective blocker of vacuolar H(+)-ATPase that increases the pH of intracellular vesicles and causes accumulation of aquaporin-2 in the Golgi compartment. Although 4-acetyldiphyllin did not inhibit forskolin-induced increases in cAMP formation and downstream activation of protein kinase A (PKA), it did prevent cAMP/PKA-dependent phosphorylation at serine 256 of aquaporin-2, which triggers the redistribution to the plasma membrane. It did not, however, prevent cAMP-induced changes to the phosphorylation status at serines 261 or 269. Last, we identified the fungicide fluconazole as an inhibitor of cAMP-mediated redistribution of aquaporin-2, but its target in this pathway remains unknown. In conclusion, our screening approach provides a method to begin dissecting molecular mechanisms underlying AVP-mediated water reabsorption, evidenced by our identification of 4-acetyldiphyllin as a modulator of aquaporin-2 trafficking.
Assuntos
Aquaporina 2/metabolismo , Benzodioxóis/farmacologia , Benzofuranos/farmacologia , ATPases Vacuolares Próton-Translocadoras/antagonistas & inibidores , Animais , Células Cultivadas , Colforsina/farmacologia , AMP Cíclico/fisiologia , Fluconazol/farmacologia , Complexo de Golgi/metabolismo , Ensaios de Triagem em Larga Escala , Humanos , Camundongos , Microscopia de Fluorescência , Fosforilação , Transporte Proteico/efeitos dos fármacos , RatosRESUMO
A-kinase anchoring proteins (AKAPs) crucially contribute to the spatial and temporal control of cellular signalling. They directly interact with a variety of protein binding partners and cellular constituents, thereby directing pools of signalling components to defined locales. In particular, AKAPs mediate compartmentalization of cAMP signalling. Alterations in AKAP expression and their interactions are associated with or cause diseases including chronic heart failure, various cancers and disorders of the immune system such as HIV. A number of cellular dysfunctions result from mutations of specific AKAPs. The link between malfunctions of single AKAP complexes and a disease makes AKAPs and their interactions interesting targets for the development of novel drugs. LINKED ARTICLES This article is part of a themed section on Novel cAMP Signalling Paradigms. To view the other articles in this section visit http://dx.doi.org/10.1111/bph.2012.166.issue-2.
