Hypotonicity increases transcription, expression, and action of Egr-1 in murine renal medullary mIMCD3 cells

Zheng Zhang, David M. Cohen

Research output: Contribution to journalArticle

8 Scopus citations

Abstract

In cells of the murine renal inner medullary collecting duct (mIMCD3) cell line, acute hypotonic shock (50% dilution of medium with sterile water but not with sterile 150 mM NaCl) increased Egr-1 mRNA abundance 2.5-fold at 6 h, as determined by Northern analysis. This increase was accompanied by increased Egr-1 transcription, as quantitated by luciferase reporter gene assay. Increased transcription was dose dependent, additive with other Egr-1 transcriptional activators, and occurred in the absence of overt cytotoxicy, as quantitated via a fluorometric viability assay. In addition, hypotonic stress increased Egr-1 protein abundance, which was accompanied by augmented Egr-1-specific DNA binding ability, as measured via electrophoretic mobility shift assay. Increased DNA binding was further associated with increased transactivation by Egr-1, demonstrated through transient transfection of mIMCD3 cells with a luciferase reporter gene driven by tandem repeats of the Egr-1 DNA consensus sequence. Taken together, these data indicate that hypotonic stress activates Egr-1 transcription, translation, DNA binding, and transactivation in renal medullary cells. This phenomenon might play a role in the acquisition of the adaptive phenotype in response to hypotonic stress in cells of the renal medulla in vivo.

Original languageEnglish (US)
Pages (from-to)F837-F842
JournalAmerican Journal of Physiology - Renal Physiology
Volume273
Issue number5 42-5
StatePublished - Dec 9 1997

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Keywords

  • Hypertonicity
  • Kidney
  • Water

ASJC Scopus subject areas

  • Physiology
  • Urology

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