Identification of an HMG-like protein involved in regulation of Na+/H+ exchanger expression.
In this study we characterized regulation of the Na+/H+ exchanger promoter in several tissue types. A conserved poly (dA:dT) region was important in regulation of the promoter. Nuclear extracts from rat myocardium and from mouse proximal tubule cells protected the poly (dA:dT) region of the NHE1 promoter. A protein from nuclear extracts also bound to the poly (dA:dT) element in gel mobility shift binding assays. The binding was specific and was removed by mutations in the poly (dA:dT) region. Characterization of the binding to the poly (dA:dT) region in gel mobility shift assays showed that it was reduced by high concentrations of the divalent cations Mg++ and Mn++. The inhibition by divalent cations was reduced by decreasing the pH of the binding assay. N-terminal sequencing of the poly (dA:dT) binding protein showed that it was a member of the HMG (high mobility group) family of nuclear proteins which are important in cell growth and proliferation. The results are the first direct detection of a protein that regulates the NHE1 promoter.
Wang
H
H
Department of Pediatrics, Faculty of Medicine, University of Alberta, Edmonton, Canada.
Yang
W
W
Fliegel
L
L
D016475:3T3 Cells / Q000378:metabolism; D000595:Amino Acid Sequence; D000818:Animals; D018983:DNA Footprinting; D006609:High Mobility Group Proteins / Q000235:genetics / Q000302:isolation & purification* / Q000378:metabolism; D007668:Kidney / Q000166:cytology / Q000378:metabolism; D051379:Mice; D008969:Molecular Sequence Data; D009206:Myocardium / Q000166:cytology / Q000378:metabolism*; D011067:Poly dA-dT / Q000235:genetics / Q000378:metabolism; D011401:Promoter Regions, Genetic / Q000235:genetics*; D051381:Rats; D016415:Sequence Alignment; D017386:Sequence Homology, Amino Acid; D017923:Sodium-Hydrogen Exchangers / Q000235:genetics* / Q000378:metabolism; D014157:Transcription Factors / Q000378:metabolism
D006609:High Mobility Group Proteins; D017923:Sodium-Hydrogen Exchangers; D014157:Transcription Factors; D011067:Poly dA-dT