期刊
EUROPEAN JOURNAL OF PHARMACOLOGY
卷 732, 期 -, 页码 32-42出版社
ELSEVIER SCIENCE BV
DOI: 10.1016/j.ejphar.2014.03.005
关键词
Epithelial Na+ channel; Serum and glucocorticoid regulated; kinase 1; Protein kinase A; Pulmonary Na+ absorption; Cellular signalling
资金
- MRC
- BBRC
- Government of Malaysia
- BBSRC [BB/E013597/1] Funding Source: UKRI
- MRC [G1001173] Funding Source: UKRI
- Biotechnology and Biological Sciences Research Council [BB/E013597/1] Funding Source: researchfish
- Medical Research Council [G1001173] Funding Source: researchfish
Neural precursor cell expressed, developmentally down-regulated protein 4-2 (Nedd4-2) mediates the internalisation / degradation of epithelial Na+ channel subunits (alpha-, beta- and gamma-ENaC). Serum / glucocorticoid inducible kinase 1 (SGK1) and protein kinase A (PKA) both appear to inhibit this process by phosphorylating Nedd4-2-Ser(221), -Ser(327) and -Thr(246). This Nedd4-2 inactivation process is thought to be central to the hormonal control of Na+ absorption. The present study of H441 human airway epithelial cells therefore explores the effects of SGK1 and / or PKA upon the phosphorylation / abundance of endogenous Nedd4-2; the surface expression of ENaC subunits, and electrogenic Na+ transport. Effects on Nedd4-2 phosphorylation/abundance and the surface expression of ENaC were monitored by western analysis, whilst Na+ absorption was quantified electrometrically. Acutely (20min) activating PKA in glucocorticoid-deprived (24h) cells increased the abundance of Ser(221)-phosphorylated, Ser(327)-phosphorylated and total Nedd4-2 without altering the abundance of Thr(246)-phosphorylated Nedd4-2. Activating PKA under these conditions did not cause a co-ordinated increase in the surface abundance of alpha-, beta- and.-ENaC and had only a very small effect upon electrogenic Na+ absorption. Activating PKA (20min) in glucocorticoid-treated (0.2 mu M dexamethasone, 24h) cells, on the other hand, increased the abundance of Ser(221)-, Ser327- and Thr(246)-phosphorylated and total Nedd4-2; increased the surface abundance of alpha-,beta- and gamma-ENaC and evoked a clear stimulation of Na+ transport. Chronic glucocorticoid stimulation therefore appears to allow cAMP-dependent control of Na+ absorption by facilitating the effects of PKA upon the Nedd4-2 and ENaC subunits. (C) 2014 The Authors. Published by Elsevier B.V.
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