The protein kinase A pathway contributes to Hg2+-induced alterations in phosphorylation and subcellular distribution of occludin associated with increased tight junction permeability of salivary epithelial cell monolayers.
J Pharmacol Exp Ther
; 326(3): 829-37, 2008 Sep.
Article
em En
| MEDLINE
| ID: mdl-18550693
ABSTRACT
Hg(2+) is commonly used as an inhibitor of many aquaporins during measurements of transcellular water transport. To investigate whether it could also act on the paracellular water transport pathway, we asked whether addition of Hg(2+) affected transport of radiolabeled probes through tight junctions of a salivary epithelial cell monolayer. Inclusion of 1 mM Hg(2+) decreased transepithelial electrical resistance by 8-fold and augmented mannitol and raffinose flux by 13-fold, which translated into an estimated 44% increase in pore radius at the tight junction. These Hg(2+)-induced effects could be partially blocked by the protein kinase A (PKA) inhibitor N-[2-((p-bromocinnamyl) amino) ethyl]-5-isoquinolinesulfonamide, 2HCl (H89), suggesting that both-PKA dependent and PKA-independent mechanisms contribute to tight junction regulation. Western blot analyses showed a 2-fold decrease in tight junction-associated occludin after Hg(2+) treatment and the presence of a novel hyperphosphorylated form of occludin in the cytoplasmic fraction. These findings were corroborated by confocal imaging. The results from this study reveal a novel contribution of the PKA pathway in Hg(2+)-induced regulation of tight junction permeability in the salivary epithelial barrier. Therapeutically, this could be explored for pharmacological intervention in the treatment of dry mouth, Sjögren's syndrome, and possibly other disorders of fluid transport.
Texto completo:
1
Base de dados:
MEDLINE
Assunto principal:
Permeabilidade da Membrana Celular
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Proteínas Quinases Dependentes de AMP Cíclico
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Junções Íntimas
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Células Epiteliais
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Proteínas de Membrana
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Mercúrio
Tipo de estudo:
Risk_factors_studies
Limite:
Animals
Idioma:
En
Revista:
J Pharmacol Exp Ther
Ano de publicação:
2008
Tipo de documento:
Article
País de afiliação:
Estados Unidos