Short interfering RNA-mediated silencing of glutaredoxin 2 increases the sensitivity of HeLa cells toward doxorubicin and phenylarsine oxide

Lillig, Christopher Horst; Lönn, Maria; Enoksson, Mari; Fernandes, Aristi P.; Holmgren, Arne

doi:10.1073/pnas.0401896101

Cited by 142 publications

(105 citation statements)

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“…Depletion of mitochondrial GSH also potentiated peroxide accumulation and sensitized cells to cell death (8,157). Small interferring RNA (siRNA) for Grx-2 increased sensitivity to doxorubicin, whereas overexpression of mitochondrial Grx-2 inhibited cardiolipin loss and prevented apoptosis induced by doxorubicin (41,111). Because Trx and GSH protect against two-electron oxidants, this in vitro research points to the plausibility of oxidant-induce cell death mechanisms signaled by nonradical reactions, which disrupt redox control.…”

Section: Oxidative Stress As a Disruption Of Redox Signaling And Controlmentioning

confidence: 99%

Radical-free biology of oxidative stress

Jones¹

2008

American Journal of Physiology-Cell Physiology

1,032

839

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Free radical-induced macromolecular damage has been studied extensively as a mechanism of oxidative stress, but large-scale intervention trials with free radical scavenging antioxidant supplements show little benefit in humans. The present review summarizes data supporting a complementary hypothesis for oxidative stress in disease that can occur without free radicals. This hypothesis, which is termed the "redox hypothesis," is that oxidative stress occurs as a consequence of disruption of thiol redox circuits, which normally function in cell signaling and physiological regulation. The redox states of thiol systems are sensitive to twoelectron oxidants and controlled by the thioredoxins (Trx), glutathione (GSH), and cysteine (Cys). Trx and GSH systems are maintained under stable, but nonequilibrium conditions, due to a continuous oxidation of cell thiols at a rate of about 0.5% of the total thiol pool per minute. Redox-sensitive thiols are critical for signal transduction (e.g., H-Ras, PTP-1B), transcription factor binding to DNA (e.g., Nrf-2, nuclear factor-B), receptor activation (e.g., ␣IIb␤3 integrin in platelet activation), and other processes. Nonradical oxidants, including peroxides, aldehydes, quinones, and epoxides, are generated enzymatically from both endogenous and exogenous precursors and do not require free radicals as intermediates to oxidize or modify these thiols. Because of the nonequilibrium conditions in the thiol pathways, aberrant generation of nonradical oxidants at rates comparable to normal oxidation may be sufficient to disrupt function. Considerable opportunity exists to elucidate specific thiol control pathways and develop interventional strategies to restore normal redox control and protect against oxidative stress in aging and age-related disease.thioredoxin; glutathione; cysteine; hydrogen peroxide; redox signaling; protein thiol ONE OF THE GREAT REDOX BIOLOGISTS of the past century, Howard S. Mason, professed that to advance science, a scientist must interpret observations at the limit of their meaning. The present review of the redox biology of thiol systems addresses the possibility that disruption of the function and homeostasis of thiol systems is the most central feature of oxidative stress that contributes to mechanisms of aging and age-related disease. I have termed this the "redox hypothesis" to facilitate distinction from free radical hypotheses.Many proteins contain redox-sensitive thiols, and reactions of thiol systems occur largely by nonradical two-electron transfers. Accumulating data show that central thiol-disulfide couples are maintained under nonequilibrium conditions in biological systems. This presents a condition wherein changes in abundance and distribution of redox catalysts and changes in rates of generation of relevant oxidants (e.g., peroxides) and precursors for NADPH supply can account for pathological effects of oxidative stress through altered functions of enzymes, receptors, transporters, transcription factors, and structural elements, without free ra...

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Section: Oxidative Stress As a Disruption Of Redox Signaling And Controlmentioning

confidence: 99%

Radical-free biology of oxidative stress

Jones¹

2008

American Journal of Physiology-Cell Physiology

1,032

839

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“…Previous studies (12,14) have revealed that GLRX2 is central in mitochondrial redox regulation. An RNA interference-induced GLRX2 knockdown sensitized mitochondria toward oxidative damage and apoptosis (12), indicating that GLRX2 could be an interesting intervention point in cancer therapy for sensitizing cells for apoptotic stimuli. It is conceivable that GLRX2 has several roles due to its enzymatic function in glutathionylation and deglutathionylation reactions.…”

Section: Structural Organization Of Dimeric Glrx2 Containing a [2fe-2s]mentioning

confidence: 99%

“…A further striking feature of GLRX2 is that it appears to be destined to function enzymatically primarily under oxidative conditions. First, high GSH/GSSG ratios will drive the GLRX2 equilibrium into a quiescent dimeric Fe-S-bound form (12,14), which can readily be activated as soon as the GSH/GSSG ratio drops under oxidative conditions. Second, GSH appears to be a direct inhibitor, as demonstrated by the non-productive complex of monomeric GLRX2 with reduced glutathione.…”

Section: Structural Organization Of Dimeric Glrx2 Containing a [2fe-2s]mentioning

confidence: 99%

“…The small interfering RNA-mediated down-regulation of mitochondrial GLRX2 resulted in dramatically increased sensitivity toward apoptotic stimuli such as doxorubicin or phenylarsine oxide (12), whereas overexpression of GLRX2 prevented cardiolipin oxidation, cytochrome c release, * The costs of publication of this article were defrayed in part by the payment of page charges. This article must therefore be hereby marked "advertisement" in accordance with 18 U.S.C.…”

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confidence: 99%

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Reversible Sequestration of Active Site Cysteines in a 2Fe-2S-bridged Dimer Provides a Mechanism for Glutaredoxin 2 Regulation in Human Mitochondria

Johansson¹,

Kavanagh²,

Gileadi

et al. 2007

Journal of Biological Chemistry

134

161

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Human mitochondrial glutaredoxin 2 (GLRX2), which controls intracellular redox balance and apoptosis, exists in a dynamic equilibrium of enzymatically active monomers and quiescent dimers. Crystal structures of both monomeric and dimeric forms of human GLRX2 reveal a distinct glutathione binding mode and show a 2Fe-2S-bridged dimer. The iron-sulfur cluster is coordinated through the N-terminal active site cysteine, Cys-37, and reduced glutathione. The structures indicate that the enzyme can be inhibited by a high GSH/GSSG ratio either by forming a 2Fe-2S-bridged dimer that locks away the N-terminal active site cysteine or by binding non-covalently and blocking the active site as seen in the monomer. The properties that permit GLRX2, and not other glutaredoxins, to form an iron-sulfur-containing dimer are likely due to the proline-toserine substitution in the active site motif, allowing the main chain more flexibility in this area and providing polar interaction with the stabilizing glutathione. This appears to be a novel use of an iron-sulfur cluster in which binding of the cluster inactivates the protein by sequestering active site residues and where loss of the cluster through changes in subcellular redox status creates a catalytically active protein. Under oxidizing conditions, the dimers would readily separate into iron-free active monomers, providing a structural explanation for glutaredoxin activation under oxidative stress.

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“…Conversely, knockdown of Grx2 sensitizes HeLa cells to anticancer drugs (63). A study indicated that Grx2 also has an anti-apoptotic function.…”

Section: Discussionmentioning

confidence: 99%

BMI-1 is important in bufalin-induced apoptosis of K562 cells

Lian

Wang

Wei

et al. 2014

Molecular Medicine Reports

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Abstract. The purpose of this study was to analyze the effects of bufalin on the gene expression of K562 cells and on the expression of BMI-1 pathway constituents in K562 cell apoptosis. K562 cells were treated with bufalin, and the inhibition rate and apoptosis were detected by an MTT assay, flow cytometry and a microarray assay. BMI-1, p16 INK4a and p14 ARF were examined by quantitative polymerase chain reaction (qPCR). Bufalin induced significant changes in the gene expression of the K562 cells; 4296 genes were differentially expressed, 2185 were upregulated and 2111 were downregulated. The most upregulated genes were associated with transcription regulation, while the most downregulated genes were associated with the non-coding RNA metabolic processes and DNA repair. qPCR analysis demonstrated that BMI-1 was overexpressed in the K562 cells. Bufalin is able to downregulate BMI-1 expression levels in K562 cells prematurely and cause an increase in the expression levels of p16 INK4a and p14 ARF . Moreover, bufalin downregulated BCR/ABL expression levels in a time-dependent manner, and the expression of BCR/ABL was not associated with the upregulation or downregulation of BMI-1 expression. Bufalin may induce K562 cell apoptosis by downregulating BMI-1 expression levels and accordingly upregulating the expression levels of p16 INK4a and p14 ARF . Bufalin may also induce K562 cell apoptosis via downregulating BCR/ABL expression levels, and this pathway may be independent of the BMI-1 pathway.

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Short interfering RNA-mediated silencing of glutaredoxin 2 increases the sensitivity of HeLa cells toward doxorubicin and phenylarsine oxide

Cited by 142 publications

References 55 publications

Radical-free biology of oxidative stress

Radical-free biology of oxidative stress

Reversible Sequestration of Active Site Cysteines in a 2Fe-2S-bridged Dimer Provides a Mechanism for Glutaredoxin 2 Regulation in Human Mitochondria

BMI-1 is important in bufalin-induced apoptosis of K562 cells

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