COMPARATIVE ROLE OF ANTIOXIDANTS FOR MODULATION OF AP-1 AND NF-B AND THEIR ROLE FOR HEME OXYGENASE-1 GENE EXPRESSION IN THE LIVER AFTER HEMORRHAGIC SHOCK

AbstractStress response genes including heat shock proteins are induced under a variety of conditions to confer cellular protection. This study investigated the role of calcium signaling in the induction of two stress response genes, heme oxygenase-1/hsp32 and hsp70, in isolated rat hepatocytes. Both genes were induced by cellular glutathione depletion. This induction could be inhibited by BAPTA-AM. Culturing in a calcium-free medium prevented the induction of hsp70 gene expression after glutathione depletion without affecting heme oxygenase-1 gene expression. Thapsigargin increased the gene expression of heme oxygenase-1 but not that of hsp70. Thapsigargin-induced heme oxygenase-1 induction was completely inhibited by BAPTA-AM. Incubation with the Ca2+-ionophore A23187 augmented heme oxygenase-1 (two-fold) and hsp70 (5.2-fold) mRNA levels. Our data suggests a significant role of Ca2+-dependent pathways in the induction of the two stress genes. An increase in the cytoplasmic Ca2+ activity seems to play a key role in the cascade of signaling leading to the induction of the two genes. However, the source of Ca2+ that fluxes into the cytoplasm seems to be different. Our data provides evidence for a compartmentalization of calcium fluxes, i.e. the Ca2+ flux from intracellular stores (e.g. the endoplasmic reticulum) plays a major role in the induction of heme oxygenase-1. By contrast, Ca2+ flux from the extracellular medium seems to be a mechanism initiating the cellular signaling cascade leading to hsp70 gene induction.

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Differential Effects Between Maotai and Ethanol on Hepatic Gene Expression in Mice: Possible Role of Metallothionein and Heme Oxygenase-1 Induction by Maotai

Experimental Biology and Medicine ◽

10.1177/153537020623100913 ◽

2006 ◽

Vol 231 (9) ◽

pp. 1535-1541 ◽

Cited By ~ 3

Author(s):

Jie Liu ◽

Min-Liang Cheng ◽

Jin-Zheng Shi ◽

Qin Yang ◽

Jun Wu ◽

...

Keyword(s):

Gene Expression ◽

Heme Oxygenase ◽

Heme Oxygenase 1 ◽

Hepatic Gene Expression ◽

Differential Effects

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Role of Bach-1 in Regulation of Heme Oxygenase-1 in Human Liver Cells

Journal of Biological Chemistry ◽

10.1074/jbc.m409463200 ◽

2004 ◽

Vol 279 (50) ◽

pp. 51769-51774 ◽

Cited By ~ 54

Author(s):

Ying Shan ◽

Richard W. Lambrecht ◽

Tahereh Ghaziani ◽

Susan E. Donohue ◽

Herbert L. Bonkovsky

Keyword(s):

Gene Expression ◽

Heme Oxygenase ◽

Antioxidant Defense ◽

Heme Oxygenase 1 ◽

Small Interfering Rnas ◽

Protein Levels ◽

Defense Enzyme ◽

Antioxidant Defense Enzyme ◽

Si Rna

Heme oxygenase-1 is an antioxidant defense enzyme that converts heme to biliverdin, iron, and carbon monoxide. Bach-1 is a bZip protein that forms heterodimers with small Maf proteins and was reported recently to down-regulate theHO-1gene in mice. Using small interfering RNAs targeted to human Bach-1 mRNA, we investigated whether modulation of human hepatic Bach-1 expression by small interfering (si)RNA technology influences heme oxygenase-1 gene expression. We found that Bach-1 siRNAs transfected into Huh-7 cells significantly reduced Bach-1 mRNA and protein levels ∼80%, compared with non siRNA-treated cells. In contrast, transfection with the same amounts of nonspecific control duplexes or LaminB2-duplex did not reduce Bach-1 mRNA or protein levels, confirming the specificity of Bach-1 siRNA. Expression of the heme oxygenase-1 gene in Bach-1 siRNA-transfected cells was up-regulated 7-fold, compared with cells without Bach-1 siRNA. The effect of increasing concentrations of heme to up-regulate levels of heme oxygenase-1 was more pronounced when Bach-1 siRNA was present. Taken together, these results indicated that Bach-1 has a specific and selective ability to repress expression of human hepatic heme oxygenase-1. Silencing of Bach-1 by siRNAs is a useful method for up-regulatingHO-1gene expression. Exogenous heme produces additional up-regulation, beyond that produced by Bach-1 siRNAs, suggesting that heme does not act solely through its effects on Bach-1.

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