title: Interferon-gamma-induced STAT1-mediated membrane retention of NHE1 and associated proteins ezrin, radixin and moesin in HT-29 cells.
abstract: This study evaluated the effect of interferon-gamma (IFN-gamma) upon the function and expression of type 1 Na(+)/H+ exchanger (NHE1) in human intestinal epithelial HT-29 cells, namely that concerning the abundance of surface NHE1 and NHE1 binding to the ezrin, radixin and moesin (ERM) family of proteins. HT-29 cells express endogenous NHE1 and the ERM family of proteins that retain the localization of NHE1 in the membrane. Long-term exposure (24 h) of HT-29 cells to IFN-gamma resulted in a concentration-dependent decrease in NHE1 activity. Inhibition of NHE1 activity by IFN-gamma was absent after pretreatment with cariporide. The long-term exposure to IFN-gamma was accompanied by increase in surface NHE1 and ERM abundance and no changes in total NHE1 and ERM abundance. Inhibition of signal transducer and activator transcription factor 1 (STAT1) with epigallocatechin-3-gallate (EGCG) prevented the inhibitory effect of IFN-gamma. Treatment with IFN-gamma activated phospho-STAT1 was markedly attenuated by EGCG. The IFN-gamma-induced increase in surface NHE1 and ERM abundance was prevented by EGCG. In conclusion, long-term inhibition of NHE1 activity by IFN-gamma involves STAT1 phosphorylation and is accompanied by increased abundance of surface NHE1 and the NHE1 membrane anchoring ERM proteins.
authors.affiliation: Institute of Pharmacology and Therapeutics, Faculty of Medicine, 4200 Porto, Portugal.
authors.forename: Fernando
authors.initials: F
authors.lastname: Magro
authors.forename: Sónia
authors.initials: S
authors.lastname: Fraga
authors.forename: Patrício
authors.initials: P
authors.lastname: Soares-da-Silva
mesh_terms: D002392:Catechin / Q000031:analogs & derivatives / Q000494:pharmacology; D027682:Cation Transport Proteins / Q000037:antagonists & inhibitors* / Q000378:metabolism; D002462:Cell Membrane / Q000737:chemistry; D004268:DNA-Binding Proteins / Q000378:metabolism*; D004305:Dose-Response Relationship, Drug; D019073:HT29 Cells; D006801:Humans; D006863:Hydrogen-Ion Concentration; D007371:Interferon-gamma / Q000494:pharmacology*; D008565:Membrane Proteins / Q000037:antagonists & inhibitors* / Q000378:metabolism; D050794:STAT1 Transcription Factor / Q000502:physiology*; D000074082:Sodium-Hydrogen Exchanger 1; D017923:Sodium-Hydrogen Exchangers / Q000037:antagonists & inhibitors* / Q000378:metabolism; D014157:Transcription Factors / Q000378:metabolism*
chemical_list: D027682:Cation Transport Proteins; D004268:DNA-Binding Proteins; C086680:ETV5 protein, human; D008565:Membrane Proteins; C490998:SLC9A1 protein, human; D050794:STAT1 Transcription Factor; D000074082:Sodium-Hydrogen Exchanger 1; D017923:Sodium-Hydrogen Exchangers; D014157:Transcription Factors; D007371:Interferon-gamma; D002392:Catechin; C045651:epigallocatechin gallate