Document Detail

Hydrogen peroxide- and cell-density-regulated expression of NADH-cytochrome b5 reductase in HeLa cells.
MedLine Citation:
PMID:  12887015     Owner:  NLM     Status:  MEDLINE    
Environmental conditions regulate the expression of different antioxidant enzymes in cell culture. We have studied the effect of cell density and hydrogen peroxide on the expression of NADH-cytochrome b5 reductase in HeLa cells. Polypeptide levels of the NADH-cytochrome b5 reductase increased about three fold in confluent HeLa cells compared to sparse cells. Addition of H2O2 to HeLa cells altered expression levels of the NADH-cytochrome b5 reducatase in a concentration-dependent way, being sparse cells more sensitive to H2O2 addition than confluent cells. The presence of pyruvate, a H2O2 scavenger, produced a significant increment (200%) in the levels of NADH-cytochrome b5 reductase in sparse cells, but less increase (25%) in confluent cells, suggesting that generation of endogenous H2O2 could repress NADH-cytochrome b5 reductase expression, particularly in sparse cultures. Accordingly, confluent HeLa cells showed significantly lower levels of reactive oxygen species than cells in sparse cultures. Addition of tert-butylhydroquinone, a compound which generates reactive oxygen species through redox cycling, also reduced expression of the NADH-cytochrome b5 reductase. Increments in several antioxidant enzymes taking place during confluency could participate in the increase of NADH-cytochrome b5 reductase expression by reducing reactive oxygen species levels in cells. Overall, our results support that acute oxidative stress caused by H2O2 inhibits the expression levels of NADH-cytochrome b5 reductase, most likely due to inhibition of SP1 transcriptional activity. On the other hand, adaptation to H2O2 involved increased expression of the cytochrome b5 reductase, supporting the existence of additional regulatory mechanisms.
Rosario I Bello; Francisco J Alcaín; Consuelo Gómez-Díaz; Guillermo López-Lluch; Plácido Navas; José M Villalba
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't    
Journal Detail:
Title:  Journal of bioenergetics and biomembranes     Volume:  35     ISSN:  0145-479X     ISO Abbreviation:  J. Bioenerg. Biomembr.     Publication Date:  2003 Apr 
Date Detail:
Created Date:  2003-07-30     Completed Date:  2004-04-06     Revised Date:  2006-11-15    
Medline Journal Info:
Nlm Unique ID:  7701859     Medline TA:  J Bioenerg Biomembr     Country:  United States    
Other Details:
Languages:  eng     Pagination:  169-79     Citation Subset:  IM    
Departamento de Biología Celular, Fisiología e Inmunología, Facultad de Ciencias, Campus Universitario de Rabanales, Edificio Severo Ochoa, Universidad de Córdoba, 14014-Córdoba, Spain.
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MeSH Terms
Cell Count*
Cytochrome-B(5) Reductase / metabolism*
Dose-Response Relationship, Drug
Gene Expression Regulation, Enzymologic / drug effects*
Hela Cells
Hydrogen Peroxide / pharmacology*
Reg. No./Substance:
7722-84-1/Hydrogen Peroxide; EC Reductase

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