Nitric oxide activation of Keap1/Nrf2 signaling in human colon carcinoma cells

Li, Chun-Qi; Kim, Min Young; Godoy, Luiz C.; Thiantanawat, Apinya; Trudel, Laura J.; Wogan, Gerald N.

doi:10.1073/pnas.0907539106

Cited by 97 publications

(82 citation statements)

References 35 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…4: D and E), suggesting that auranofin indirectly changes the Keap1 structure (i.e., it modified Keap1 via iNOS signaling). Recent reports that NO provokes (S)-nitrosation of cysteine residues in Keap1 and induces nuclear accumulation of Nrf2 (34,35), in combination with our data, suggest the possibility that auranofin triggers Keap1 modification through (S)-nitrosation and results in the nuclear translocation of Nrf2. Further study is required to understand the mechanism of auranofin-mediated Keap1 modifications.…”

Section: Discussionsupporting

confidence: 56%

Auranofin, a Gold(I)-Containing Antirheumatic Compound, Activates Keap1/Nrf2 Signaling via Rac1/iNOS Signal and Mitogen-Activated Protein Kinase Activation

Kim

Park

et al. 2010

J Pharmacol Sci

View full text Add to dashboard Cite

Abstract. Auranofin (2,3,4,6-tetra-O-acetyl-1-thio-β-D-glucopyranosato-S-[triethylphosphine] gold) is a gold(I)-containing antirheumatic drug that possesses anti-inflammatory properties. The pharmacological activity of this drug is associated with its ability to induce heme oxygenase-1 (HO-1). However, the mechanism underlying auranofin-mediated HO-1 induction remains unclear. We investigated the action of auranofin on activation of nuclear factor erythroid 2-related factor 2 (Nrf2), an activator of HO-1. Auranofin elevated cellular levels of Nrf2 by increasing protein stability but not transcriptional activation. Coimmunoprecipitation and Western blot analysis indicated that auranofin inhibited Nrf2 degradation by inducing the dissociation of the Nrf2 / Kelchlike ECH-associated protein 1 (Keap1) complex, which resulted in nuclear accumulation of Nrf2. In addition, auranofin treatment activated cellular Rac1 and induced inducible nitric oxide synthase (iNOS) expression. An inhibitor of Rac1 (NSC23766) blocked the iNOS induction as well as Nrf2 activation and HO-1 expression. N G -nitro-L-arginine methyl ester and aminoguanidine, inhibitors of iNOS, diminished the auranofin-induced Nrf2 activation and HO-1 expression. Phosphorylation of mitogen-activated protein kinases (MAPKs) was increased by auranofin treatment, and inhibitors of MAPKs partially diminished the Nrf2 activation. A chromatin immunoprecipitation assay showed that the Nrf2 activated by auranofin was involved in transactivation of the HO-1 gene. These findings indicate that auranofin leads to HO-1 upregulation by activating Keap1/Nrf2 signaling via Rac1/iNOS induction and MAPK activation.

show abstract

Section: Discussionsupporting

confidence: 56%

Auranofin, a Gold(I)-Containing Antirheumatic Compound, Activates Keap1/Nrf2 Signaling via Rac1/iNOS Signal and Mitogen-Activated Protein Kinase Activation

Kim

Park

et al. 2010

J Pharmacol Sci

View full text Add to dashboard Cite

show abstract

“…Cells cultured at a density of 70-80% confluence were plated in 60-mm dishes 24 h before exposure to NO. Using the NO-delivery system described elsewhere (28,29), equipped to maintain NO at steady-state concentration, cells were exposed to 11 μM NO for the indicated time points to produce the following cumulative doses: 622 μM•min (70 min); 1,244 μM•min (140 min); 1,866 μM•min (210 min); and 2,488 μM•min (280 min). Cells exposed to 5% CO 2 :21% O 2 :74% N 2 served as controls.…”

Section: Methodsmentioning

confidence: 99%

Reactive nitrogen species regulate autophagy through ATM-AMPK-TSC2–mediated suppression of mTORC1

Tripathi

Chowdhury

Trudel

et al. 2013

Proc. Natl. Acad. Sci. U.S.A.

Self Cite

219

180

View full text Add to dashboard Cite

Reactive intermediates such as reactive nitrogen species play essential roles in the cell as signaling molecules but, in excess, constitute a major source of cellular damage. We found that nitrosative stress induced by steady-state nitric oxide (NO) caused rapid activation of an ATM damage-response pathway leading to downstream signaling by this stress kinase to LKB1 and AMPK kinases, and activation of the TSC tumor suppressor. As a result, in an ATM-, LKB1-, TSC-dependent fashion, mTORC1 was repressed, as evidenced by decreased phosphorylation of S6K, 4E-BP1, and ULK1, direct targets of the mTORC1 kinase. Decreased ULK1 phosphorylation by mTORC1 at S757 and activation of AMPK to phosphorylate ULK1 at S317 in response to nitrosative stress resulted in increased autophagy: the LC3-II/LC3-I ratio increased as did GFP-LC3 puncta and acidic vesicles; p62 levels decreased in a lysosomedependent manner, confirming an NO-induced increase in autophagic flux. Induction of autophagy by NO correlated with loss of cell viability, suggesting that, in this setting, autophagy was functioning primarily as a cytotoxic response to excess nitrosative stress. These data identify a nitrosative-stress signaling pathway that engages ATM and the LKB1 and TSC2 tumor suppressors to repress mTORC1 and regulate autophagy. As cancer cells are particularly sensitive to nitrosative stress, these data open another path for therapies capitalizing on the ability of reactive nitrogen species to induce autophagy-mediated cell death. signal transduction | cancer therapyA utophagy is a self-digestion process by which a eukaryotic cell degrades and recycles aggregate-prone proteins, macromolecules, and organelles. During autophagy, cytoplasmic contents are sequestered in double-membrane bound vesicles called autophagosomes and delivered to lysosomes for degradation, thereby allowing cells to eliminate and recycle the contents (1-3). Autophagy participates in both prosurvival (recycling of cellular building blocks) and prodeath (excess catalysis) pathways. A comprehensive understanding of signaling pathways that regulate autophagy holds great promise for new therapeutic opportunities by opening the possibility to compromise prosurvival autophagic pathways that enable tumor cells to evade therapy, or by promoting prodeath autophagic pathways to kill cancer cells.The classical pathway regulating autophagy in mammalian cells involves the serine/threonine kinase, mammalian target of rapamycin (mTOR). Active mTOR kinase in the mTORC1 complex phosphorylates and inhibits ULK1, a key proautophagy adapter involved in nucleation of the autophagophore membrane. Inactivation of mTORC1, either pharmacologically with rapamycin or via activation of the tuberous sclerosis complex (TSC) tumor suppressor, leads to downstream dephosphorylation events, including loss of ULK1 phosphorylation at S757. The TSC1/2 heterodimer is itself regulated by upstream kinases, including the AMP-activated protein kinase (AMPK), which regulates several metabolic processes and activates t...

show abstract

“…Compound 30 was the most active in modifying Keap1 and treatment with 30 was accompanied by nuclear accumulation of both Nrf2 and Keap1, with qualitatively similar kinetics, while cytosolic Keap1 was dissipated. Direct treatment of cells with NO leads to upregulation of HO-1 and NQO1 and likely nitrosylated cysteine of Keap1 (36). The biotin switch assay used in this study employed the much weaker reductant ascorbate that does not reduce disulfides.…”

Section: Class E Compoundsmentioning

confidence: 99%

Chemistry of the Cysteine Sensors in Kelch-Like ECH-Associated Protein 1

Holland

Fishbein

2010

Antioxidants & Redox Signaling

View full text Add to dashboard Cite

The protein Kelch-like ECH-associated protein 1 (Keap1) is a cysteine-rich regulatory and scaffold protein. Human Keap1 contains 27 cysteines. Some of these cysteines are believed to mediate derepression of the transcription factor nuclear factor (erythroid-derived 2)-like 2 (Nrf2), which subsequently upregulates phase 2 enzymes, in response to electrophilic=oxidative assault. Some current models depict a highly select group of two and possibly a few more cysteine residues as key sensors. The assumptions and approaches undergirding these models are commented upon. The chemical reactivity of the cysteines of Keap1 toward an array of electrophiles and one oxidant is reviewed. A number of reports in the recent literature of molecules that putatively modify cysteines of Keap1 are also included. Insights into the current molecular basis of electrophile=oxidant activation of the Nrf2 pathway via reaction at cysteines of Keap1 are discussed. Finally, important knowns and unknowns are summarized. Antioxid. Redox Signal. 13, 1749-1761.

show abstract

Nitric oxide activation of Keap1/Nrf2 signaling in human colon carcinoma cells

Abstract: The transcription factor NF-E2-related nuclear factor 2 (Nrf2) regulates expression of genes that protect cells from oxidative damage. Here, we characterized nitric oxide (

Cited by 97 publications

References 35 publications

Auranofin, a Gold(I)-Containing Antirheumatic Compound, Activates Keap1/Nrf2 Signaling via Rac1/iNOS Signal and Mitogen-Activated Protein Kinase Activation

Auranofin, a Gold(I)-Containing Antirheumatic Compound, Activates Keap1/Nrf2 Signaling via Rac1/iNOS Signal and Mitogen-Activated Protein Kinase Activation

Reactive nitrogen species regulate autophagy through ATM-AMPK-TSC2–mediated suppression of mTORC1

Chemistry of the Cysteine Sensors in Kelch-Like ECH-Associated Protein 1

Contact Info

Product

Resources

About