Transcriptional regulation of rat Na+/H+ exchanger isoform-2 (NHE-2) gene by Sp1 transcription factor

Liqun Bai, James F. Collins, Hua Xu, Fayez K. Ghisha

Research output: Contribution to journalArticle

15 Citations (Scopus)

Abstract

The rat Na+/H+ exchanger isoform-2 (NHE-2) gene promoter lacks a TATA box and is very GC rich. A minimal promoter extending from bp -36 to +116 directs high-level expression of NHE-2 in mouse inner medullary collecting duct (mIMCD-3) cells. Four Sp1 consensus elements were found in this region. The introduction of mutations within these Sp1 consensus elements and DNA footprinting revealed that only two of them were utilized and are critical for basal transcriptional activation in mIMCD-3 cells. The use of Sp1, Sp3, and Sp4 antisera in electrophoretic mobility shift assays demonstrated that Sp1, Sp3, and Sp4 bound to this minimal promoter. We further analyzed the transcriptional regulation of NHE-2 by members of the Sp1 multigene family. In Drosophila SL2 cells, which lack endogenous Sp1, the minimal promoter cannot drive transcription. Introduction of Sp1 activated transcription over 100-fold, suggesting that Sp1 is critical for transcriptional regulation. However, neither Sp3 nor Sp4 was able to activate transcription in these cells. Furthermore, in mIMCD-3 cells, Sp1-mediated transcriptional activation was repressed by expression of Sp3 and Sp4. These data suggest that Sp1 is critical for the basal promoter function of rat NHE-2 and that Sp3 and Sp4 may repress transcriptional activation by competing with Sp1 for binding to core cis-elements.

Original languageEnglish (US)
JournalAmerican Journal of Physiology - Cell Physiology
Volume280
Issue number5 49-5
StatePublished - 2001

Fingerprint

Sp1 Transcription Factor
Sodium-Hydrogen Antiporter
Rats
Protein Isoforms
Transcription
Genes
Chemical activation
Transcriptional Activation
DNA Footprinting
Electrophoretic mobility
TATA Box
Ducts
Immune Sera
Electrophoretic Mobility Shift Assay
Assays
Multigene Family
Drosophila
DNA
Mutation

Keywords

  • Drosophila SL2 cells
  • mIMCD-3 cells
  • Sodium-hydrogen exchanger
  • Sp3
  • Sp4

ASJC Scopus subject areas

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

Cite this

Transcriptional regulation of rat Na+/H+ exchanger isoform-2 (NHE-2) gene by Sp1 transcription factor. / Bai, Liqun; Collins, James F.; Xu, Hua; Ghisha, Fayez K.

In: American Journal of Physiology - Cell Physiology, Vol. 280, No. 5 49-5, 2001.

Research output: Contribution to journalArticle

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