RhoA required for acid-induced stress fiber formation and trafficking and activation of NHE3

Xiaojing Yang, Hai Chang Huang, Helen Yin, Robert J. Alpern, Patricia A. Preisig

Research output: Contribution to journalArticlepeer-review

13 Scopus citations


Exposure to an acid load increases apical membrane Na+/H + antiporter (NHE3) activity, a process that involves exocytic trafficking of the transporter to the apical membrane. We have previously shown that an intact microfilament structure is required for this exocytic process (Yang X, Amemiya M, Peng Y, Moe OW, Preisig PA, Alpern RJ. Am J Physiol Cell Physiol 279: C410-C419, 2000). The present studies demonstrate that acid-induced stress fiber formation is required for stimulation of NHE3 activity. Formation of stress fibers is associated with acid-induced tyrosine phosphorylation and increases in protein abundance of two focal adhesion proteins, p125 FAK and paxillin. The Rho kinase inhibitor Y27632 completely blocks acid-induced stress fiber formation and the increases in apical membrane NHE3 abundance and activity, but it has no effect on acid-induced tyrosine phosphorylation of p125FAK or paxillin. Herbimycin A completely blocks acid-induced tyrosine phosphorylation of p125FAK and paxillin but only partially blocks stress fiber formation and NHE3 activation. These studies demonstrate that Rho kinase mediates acid-induced stress fiber formation, which is required for NHE3 exocytosis, and increases in NHE3 activity. Acid-induced tyrosine phosphorylation of the focal adhesion proteins p125FAK and paxillin is not Rho kinase dependent. Thus these two acid-mediated effects are associated, yet independent processes.

Original languageEnglish (US)
Pages (from-to)F1054-F1064
JournalAmerican Journal of Physiology - Renal Physiology
Issue number4
StatePublished - Oct 2007


  • Actin
  • OKP cells
  • Tyrosine phosphorylation
  • Y27632

ASJC Scopus subject areas

  • Physiology
  • Urology


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