Acute regulation of NaH exchanger NHE3 activity by protein kinase C: role of NHE3 phosphorylation

Citation
Mr. Wiederkehr et al., Acute regulation of NaH exchanger NHE3 activity by protein kinase C: role of NHE3 phosphorylation, AM J P-CELL, 45(5), 1999, pp. C1205-C1217
Citations number
30
Language
INGLESE
art.tipo
Article
Categorie Soggetti
Cell & Developmental Biology
Journal title
AMERICAN JOURNAL OF PHYSIOLOGY-CELL PHYSIOLOGY
ISSN journal
0363-6143 → ACNP
Volume
45
Issue
5
Year of publication
1999
Pages
C1205 - C1217
Database
ISI
SICI code
0363-6143(199905)45:5<C1205:ARONEN>2.0.ZU;2-O
Abstract
Acute hormonal modulation of NHE3 activity is partly mediated by kinases, i ncluding protein kinase C (PKC). We examined the role of NHE3 phosphorylati on in regulating its activity in response to PKC activation by phorbol 12-m yristate 13-acetate (PIMA). In pooled NHE-deficient fibroblasts transfected with NHE3, PMA increased NHE3 activity and phosphorylation. When six poten tial PKC target serines were mutated, NHE3 phosphorylation was drastically reduced and PMA failed to regulate NHE3 phosphorylation or function. To exa mine whether NHE3 phosphorylation is sufficient for functional regulation b y PKC, we exploited the heterogeneous response of NHE3 activity to PMA in i ndividual clones of transfectants. Clones with stimulatory, inhibitory, or null responses to PMA were observed. Despite the diverse functional respons e, changes in NHE3 phosphorylation as revealed by tryptic phosphopeptide ma ps were similar in all clones. We conclude that although phosphorylation ap pears to be necessary, it is insufficient to mediate PKC regulation of NHE3 function and factors extrinsic to the NHE3 protein must be involved.