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Histone H1 isoforms purified from rat liver bind nonspecifically to the nuclear factor 1 recognition sequence and serve as generalized transcriptional repressors

Authors
  • Gao, Bin1
  • Jaffe, Howard2
  • Kunos, George1
  • 1 Medical College of Virginia, Virginia Commonwealth University, Department of Pharmacology and Toxicology, Richmond, VA, 23298, USA , Richmond
  • 2 National Institutes of Health, National Institute on Neurological Disorders and Stroke, Bethesda, MD, 20892, USA , Bethesda
Type
Published Article
Journal
Molecular and Cellular Biochemistry
Publisher
Springer-Verlag
Publication Date
Jan 01, 1998
Volume
178
Issue
1-2
Pages
187–196
Identifiers
DOI: 10.1023/A:1006843514666
Source
Springer Nature
Keywords
License
Yellow

Abstract

Two polypeptides with molecular masses of 34 and 30 kDa were copurified from rat liver during DNA affinity purification of a sequence-specific transcription factor binding to the footprint II sequence within the P2 promoter of the rat α1B adrenergic receptor (α1BAR) gene, and were identified by microsequencing their endoproteinase Lys-C-derived peptides as histone H1d and histone H1c, respectively. Histone H1 was previously reported to bind to the nuclear factor 1 (NF1) recognition sequence, although the specificity of this binding has been controversial. Here, DNA mobility shift and supershift assays, DNase I footprinting and mutational analyses indicated that the binding of histone H1 to the NF1 sites located within footprint II of the α1BAR gene P2 promoter is nonspecific. Transient cotransfections into Hep3B cells of histone H1d cDNA with CAT constructs containing promoter regions of different genes resulted in generalized and non-specific suppression of CAT activity. The histone H1d-mediated repression of the activities of the α1BAR gene P2/CAT or β2AR gene P(-186/1307)/CAT constructs was reversed by the cotransfection of a cDNA encoding the sequence-specific transcription factor NF1/X, and the fold increase in CAT activities was similar to that obtained in the absence of histone H1d. These results suggest that sequence-specific transcription factors counteract the histone H1-mediated transcriptional repression in vivo by a true activation, which is different from the in vitro antirepression in histone H1-repressed chromatin templates (Laybourn and Kadonaga, (1991) Science 254: 238-245).

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