1. RhoA Kinase (Rock) and p90 Ribosomal S6 Kinase (p90Rsk) phosphorylation of the sodium hydrogen exchanger (NHE1) is required for lysophosphatidic acid-induced transport, cytoskeletal organization and migration.
- Author
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Wallert MA, Hammes D, Nguyen T, Kiefer L, Berthelsen N, Kern A, Anderson-Tiege K, Shabb JB, Muhonen WW, Grove BD, and Provost JJ
- Subjects
- Amino Acid Sequence, Amino Acid Substitution, Animals, Cell Line, Cell Movement drug effects, Cell Proliferation, Cricetinae, Humans, Hydrogen-Ion Concentration, Molecular Sequence Data, Phosphopeptides analysis, Phosphorylation drug effects, Recombinant Proteins biosynthesis, Recombinant Proteins genetics, Ribosomal Protein S6 Kinases, 90-kDa genetics, Sequence Alignment, Sodium-Hydrogen Exchangers genetics, Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization, rhoA GTP-Binding Protein genetics, Cytoskeleton drug effects, Lysophospholipids pharmacology, Ribosomal Protein S6 Kinases, 90-kDa metabolism, Sodium-Hydrogen Exchangers metabolism, rhoA GTP-Binding Protein metabolism
- Abstract
The sodium hydrogen exchanger isoform one (NHE1) plays a critical role coordinating asymmetric events at the leading edge of migrating cells and is regulated by a number of phosphorylation events influencing both the ion transport and cytoskeletal anchoring required for directed migration. Lysophosphatidic acid (LPA) activation of RhoA kinase (Rock) and the Ras-ERK growth factor pathway induces cytoskeletal reorganization, activates NHE1 and induces an increase in cell motility. We report that both Rock I and II stoichiometrically phosphorylate NHE1 at threonine 653 in vitro using mass spectrometry and reconstituted kinase assays. In fibroblasts expressing NHE1 alanine mutants for either Rock (T653A) or ribosomal S6 kinase (Rsk; S703A) we show that each site is partially responsible for the LPA-induced increase in transport activity while NHE1 phosphorylation by either Rock or Rsk at their respective site is sufficient for LPA stimulated stress fiber formation and migration. Furthermore, mutation of either T653 or S703 leads to a higher basal pH level and a significantly higher proliferation rate. Our results identify the direct phosphorylation of NHE1 by Rock and suggest that both RhoA and Ras pathways mediate NHE1-dependent ion transport and migration in fibroblasts., (Copyright © 2015 Elsevier Inc. All rights reserved.)
- Published
- 2015
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