Document Detail


HIV-1 Tat regulates the SOD2 basal promoter by altering Sp1/Sp3 binding activity.
MedLine Citation:
PMID:  15706661     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
Regulation of the basal manganese superoxide dismutase (SOD2) promoter depends on the transcriptional activity of the Sp family of transcription factors. Here we report that reduced expression in the presence of Tat is independent of induction with Tumor necrosis factor alpha and that Tat affects the interaction of Sp1 and Sp3 with the basal promoter. Footprinting and electrophoretic mobility shift assay (EMSA) analyses with extracts from HeLa cells showed that Sp1/Sp3 complexes populate the proximal SOD2 promoter, and that Tat leads to an increase in the binding activity of Sp3. In Drosophila S2 cells, both Sp1 and Sp3 activated the basal SOD2 promoter (88.1 +/- 39.4 fold vs. 10.3 +/- 3.5 fold, respectively), demonstrating a positive, yet lower transcriptional regulatory function for Sp3. Additionally, the inability of Sp3 to synergistically affect promoter activity indicates an efficient competition of Sp3 with Sp1 for the multiple Sp binding sites in the SOD2 basal promoter. Tat potentiated both Sp1 and Sp3 activation of the promoter in S2 cells, though the activity of Sp3 was still lower than that of Sp1. Thus, the consequence of a shift by Tat to increased Sp3-containing complexes on the basal SOD2 promoter is decreased SOD2 expression. Together, our studies demonstrate the functional importance of the interaction of Sp1, Sp3, and Tat, revealing a possible mechanism for the attenuation of basal manganese superoxide dismutase expression.
Authors:
John C Marecki; Adela Cota-Gomez; Gisela M Vaitaitis; Jennifer R Honda; Sureerut Porntadavity; Daret K St Clair; Sonia C Flores
Publication Detail:
Type:  Journal Article    
Journal Detail:
Title:  Free radical biology & medicine     Volume:  37     ISSN:  0891-5849     ISO Abbreviation:  Free Radic. Biol. Med.     Publication Date:  2004 Sep 
Date Detail:
Created Date:  2005-02-11     Completed Date:  2005-02-18     Revised Date:  2007-11-15    
Medline Journal Info:
Nlm Unique ID:  8709159     Medline TA:  Free Radic Biol Med     Country:  United States    
Other Details:
Languages:  eng     Pagination:  869-80     Citation Subset:  IM    
Affiliation:
Cardiovascular Pulmonary Research Laboratory, University of Colorado Health Sciences Center, Denver, CO 80262, USA. John.Marecki@UCHSC.edu
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MeSH Terms
Descriptor/Qualifier:
Acetylcysteine / chemistry
Animals
Binding Sites
Blotting, Northern
Blotting, Western
Cell Differentiation
Cell Line
Cell Line, Tumor
Cell Nucleus / metabolism
DNA / metabolism
DNA-Binding Proteins / genetics,  metabolism*
Drosophila
Free Radicals
Gene Expression Regulation, Viral*
Gene Products, tat / genetics*,  physiology*
HIV-1 / genetics*
Hela Cells
Humans
Luciferases / metabolism
Models, Chemical
Oxidative Stress
Plasmids / metabolism
Protein Binding
Sp1 Transcription Factor / genetics,  metabolism*
Sp3 Transcription Factor
Superoxide Dismutase / biosynthesis*,  genetics,  metabolism
Transcription Factors / genetics,  metabolism*
Transfection
tat Gene Products, Human Immunodeficiency Virus
Chemical
Reg. No./Substance:
0/DNA-Binding Proteins; 0/Free Radicals; 0/Gene Products, tat; 0/SP3 protein, human; 0/Sp1 Transcription Factor; 0/Transcription Factors; 0/tat Gene Products, Human Immunodeficiency Virus; 148710-94-5/Sp3 Transcription Factor; 616-91-1/Acetylcysteine; 9007-49-2/DNA; EC 1.13.12.-/Luciferases; EC 1.15.1.1/Superoxide Dismutase; EC 1.15.1.1/superoxide dismutase 2

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine


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