Ras signaling in the inner medullary cell response to urea and NaCl

Wei Tian, Gerry R. Boss, David Cohen

Research output: Contribution to journalArticle

30 Citations (Scopus)

Abstract

The small guanine nucleotide-binding protein Ras, activated by peptide mitogens and other stimuli, regulates downstream signaling events to influence transcription. The role of Ras in solute signaling to gene regulation was investigated in the murine inner medullary collecting duct (mIMCD3) cell line. Urea treatment (100-200 mM), but not sham treatment, increased Ras activation 124% at 2 min; the effect of NaCl did not achieve statistical significance. To determine the contribution of Ras activation to urea-inducible signal transduction, mIMCD3 cells were stably transfected with an expression plasmid encoding a dominant negative-acting N17Ras mutant driven by a dexamethasone-inducible (murine mammary tumor virus) promoter. After 24 h of induction, selected cell lines exhibited sufficient N17Ras overexpression to abolish epidermal growth factor- and hypotonicity-mediated signaling to extracellular signal-regulated kinase (ERK) phosphorylation, as determined by immunoblotting. Conditional N17Ras overexpression inhibited urea- and NaCl-inducible ERK phosphorylation by 40-50%, but only at 15 min, and not 5 min, of treatment. N17Ras induction, however, almost completely inhibited urea-inducible Egr-1 transcription, as quantitated by luciferase reporter gene assay, but failed to influence tonicity-inducible (TonE- mediated) transcription. N17Ras overexpression also blocked urea-inducible expression of the transcription factor Gadd153 but did not influence osmotic or urea-inducible apoptosis. In addition, urea treatment induced recruitment of the Ras activator Sos to the plasma membrane. Taken together, these observations suggest a role for Ras signaling in the IMCD cell response to urea stress.

Original languageEnglish (US)
JournalAmerican Journal of Physiology - Cell Physiology
Volume278
Issue number2 47-2
StatePublished - 2000

Fingerprint

Urea
Transcription
Phosphorylation
Extracellular Signal-Regulated MAP Kinases
Gammaretrovirus
Chemical activation
Cells
Cell Line
Signal transduction
Guanine Nucleotides
Cell membranes
Luciferases
Reporter Genes
Viruses
Mitogens
Immunoblotting
Epidermal Growth Factor
Gene expression
Carcinogens
Ducts

Keywords

  • Cell volume regulation, Gadd153
  • Extracellular signal- regulated kinase
  • Hypertonicity
  • Mitogen-activated protein kinase

ASJC Scopus subject areas

  • Clinical Biochemistry
  • Cell Biology
  • Physiology
  • Physiology (medical)

Cite this

Ras signaling in the inner medullary cell response to urea and NaCl. / Tian, Wei; Boss, Gerry R.; Cohen, David.

In: American Journal of Physiology - Cell Physiology, Vol. 278, No. 2 47-2, 2000.

Research output: Contribution to journalArticle

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