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Titolo:
14-3-3 binding to Na+/H+ exchanger isoform-1 is associated with serum-dependent activation of Na+/H+ exchange
Autore:
Lehoux, S; Abe, J; Florian, JA; Berk, BC;
Indirizzi:
Univ Rochester, Sch Med & Dent, Cardiol Res Ctr, Rochester, NY 14642 USA Univ Rochester Rochester NY USA 14642 ol Res Ctr, Rochester, NY 14642 USA Univ Rochester, Sch Med & Dent, Dept Med, Rochester, NY 14642 USA Univ Rochester Rochester NY USA 14642 , Dept Med, Rochester, NY 14642 USA
Titolo Testata:
JOURNAL OF BIOLOGICAL CHEMISTRY
fascicolo: 19, volume: 276, anno: 2001,
pagine: 15794 - 15800
SICI:
0021-9258(20010511)276:19<15794:1BTNEI>2.0.ZU;2-I
Fonte:
ISI
Lingua:
ENG
Soggetto:
VASCULAR SMOOTH-MUSCLE; SPONTANEOUSLY HYPERTENSIVE RAT; WISTAR-KYOTO RATS; NA-H EXCHANGE; PROTEIN-KINASE; GROWTH-FACTORS; IMMORTALIZED LYMPHOBLASTS; SIGNAL-TRANSDUCTION; PHOSPHORYLATION; CELLS;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Life Sciences
Citazioni:
45
Recensione:
Indirizzi per estratti:
Indirizzo: Berk, BC Univ Rochester, Sch Med & Dent, Cardiol Res Ctr, Box 679,601 Elmwood Ave, Rochester, NY 14642 USA Univ Rochester Box 679,601 Elmwood Ave Rochester NY USA 14642 USA
Citazione:
S. Lehoux et al., "14-3-3 binding to Na+/H+ exchanger isoform-1 is associated with serum-dependent activation of Na+/H+ exchange", J BIOL CHEM, 276(19), 2001, pp. 15794-15800

Abstract

Na+/H+ exchanger isoform-1 (NHE1), the ubiquitous form of the Na+/H+ exchanger, has increased activity in hypertensive patients and in animal models of hypertension. Furthermore, NHE1 is activated in cells stimulated with growth factors. We showed previously that activation of the exchanger is dependent on phosphorylation of serine 703 (Ser(P)(703)) by p90 ribosomal S6 kinase (RSK). Because the NHE1 sequence at Ser(P)(703) (RIGSDP) is similar toa consensus sequence (RSXSXP) specific for 14-3-3 ligands, we evaluated whether serum stimulated 14-3-3 binding to NHE1. Five different GST-NHE1 fusion proteins spanning amino acids 515-815 were phosphorylated by RSK and used as ligands in a far Western analysis; only those containing Ser(P)(703) exhibited high affinity 14-3-3 binding. In PS127A cells (NHE1-overexpressingChinese hamster fibroblasts) stimulated with 20% serum, NHE1 co-precipitation with GST-14-3-3 fusion protein increased at 5 min (5.2 +/- 0.4-fold versus control; p < 0.01) and persisted at 40 min (3.9 +/- 0.5-fold; p < 0.01). We confirmed that binding occurs at the RIGSDP motif using PS120 (NHE1 null) cells transfected with S703A-NHE1 or P705A-NHE1 (based on data indicating that 14-3-3 binding requires phosphoserine and +2 proline). Serum failedto stimulate association of 14-3-3 with these mutants. A GST-NHE1 fusion protein was phosphorylated by RSK and used as a ligand to assess the effect of 14-3-3 on protein phosphatase 1-mediated dephosphorylation of Ser(P)(703). GST-14-3-3 limited dephosphorylation (66% of initial state at 60 min) compared with GST alone (27% of initial state; p < 0.01). The protective effect of GST-14-3-3 was lost in the GST-NHE1 P705A mutant. Finally, the baseline rate of pH recovery in acid-loaded cells was equal in unstimulated cellsexpressing wild-type or P705A-NHE1, However, activation of NHE1 by serum was dramatically inhibited in cells expressing P705A-NHE1 compared with wild-type (0.13 +/- 0.02 versus 0.48 +/- 0.06 mmol of H+/min/liter, p < 0.01). These data suggest that 14-3-3 binding to NHE1 participates in serum-stimulated exchanger activation, a new function for 14-3-3.

ASDD Area Sistemi Dipartimentali e Documentali, Università di Bologna, Catalogo delle riviste ed altri periodici
Documento generato il 26/01/20 alle ore 01:19:07