Intestinal Na+-K+-ATPase activity and molecular events downstream of interferon-gamma receptor stimulation

• Type: Article in International Scientific Journal
• Date: 2004

Authors

Magro F (Author) Other; Sonia Fraga (Author) Other; Ribeiro, T (Author) Other; soares-da-silva, p (Author) FMUP

Journal

Title: British Journal of Pharmacology

Vol. 142

Pages: 1281-1292

ISSN: 0007-1188

Publisher: Wiley-Blackwell

Indexing

ISI Web of Knowledge - 13 Citations

Scopus - 14 Citations

Other information

Authenticus ID: P-000-92R

DOI: 10.1038/sj.bjp.0705895

Abstract (EN): 1 This study evaluated the effects of human interferon-gamma (IFN-gamma) on Na+-K+-ATPase activity and the intracellular signaling pathways involved in human intestinal epithelial Caco-2 cells. 2 Na+-K+-ATPase activity was determined as the difference between total and ouabain-sensitive ATPase, p38 MAP kinase activity was analyzed by Western blotting using the p38 MAP kinase assay kit. Total and phosphorylated STAT1 protein levels were detected using the PhosphoPlus(R) Stat1. 3 IFN-gamma decreased Na+-K+-ATPase activity in a time- and concentration-dependent manner. The IFN-gamma-induced decrease in Na+-K+-ATPase activity was accompanied by no changes in the abundance of alpha(1) subunit Na+-K+-ATPase. Downregulation of protein kinase C (PKC) with phorbol-12,13-dibutyrate (PDBu) prevented the inhibitory effect of IFN-gamma on Na+-K+-ATPase activity. Inhibition of Raf-1, mitogen-activated protein kinase kinase (MAPKK/MEK), p38 MAPK and STAT1 with, respectively, GW 5074, PD 98059, SB 203580 and epigallocatechin gallate prevented inhibition of Na+-K+-ATPase activity by IFN-gamma. 4 Treatment with IFN-gamma markedly increased the expression of total and phospho-STAT1, this being accompanied by activation of p38 MAPK. Activation of phospho-STAT1 by IFN-gamma was almost abolished by epigallocatechin gallate and markedly reduced by SB 203580, but insensitive to downregulation of PKC. 5 The increase in short circuit current (I-sc) by 1.0 and 2.5 mug ml(-1) amphotericin B was markedly attenuated in IFN-gamma-treated cells. However, the inhibitory effect of PDBu on the amphotericin B-induced increase in I-sc was of similar magnitude in vehicle- and IFN-gamma-treated cells. 6 It is concluded that IFN-gamma markedly attenuates Na+-K+-ATPase activity. The transduction mechanisms set into motion by IFN-gamma involve the activation of PKC downstream STAT1 phosphorylation and Raf-1, MEK, ERK2 and p38 MAPK pathways, in a complex sequence of events.

Language: English

Type (Professor's evaluation): Scientific

No. of pages: 12