Insight into the Intermolecular Recognition Mechanism between Keap1 and IKKβ Combining Homology Modelling, Protein-Protein Docking, Molecular Dynamics Simulations and Virtual Alanine Mutation

Jiang, Zhengyu; Chu, Hongxi; Xi, Meiyang; Yang, Tingting; Jia, Jianmin; Huang, Jingjie; Guo, Xiaoke; Zhang, Xiaojin; You, Qidong; Sun, Haopeng

doi:10.1371/journal.pone.0075076

Cited by 43 publications

(35 citation statements)

References 67 publications

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“…These studies showed that Keap1 regulated TNF-induced NF-κB activity via IKKβ. The E(T/S)GE motif, which is found only in the IKKβ subunit of the IKK complex, was essential for direct interaction with the C-terminal Kelch domain of Keap1 (27,41). However, we show evidence that the entire IKK complex, along with its homolog TBK1, is significantly affected by Keap1, even though only IKKβ seemed to be ubiquitinated and possibly degraded through Keap1.…”

Section: Discussionmentioning

confidence: 55%

Keap1 regulates inflammatory signaling in Mycobacterium avium -infected human macrophages

Awuh

Haug

Mildenberger

et al. 2015

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

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Several mechanisms are involved in controlling intracellular survival of pathogenic mycobacteria in host macrophages, but how these mechanisms are regulated remains poorly understood. We report a role for Kelch-like ECH-associated protein 1 (Keap1), an oxidative stress sensor, in regulating inflammation induced by infection with Mycobacterium avium in human primary macrophages. By using confocal microscopy, we found that Keap1 associated with mycobacterial phagosomes in a time-dependent manner, whereas siRNA-mediated knockdown of Keap1 increased M. aviuminduced expression of inflammatory cytokines and type I interferons (IFNs). We show evidence of a mechanism whereby Keap1, as part of an E3 ubiquitin ligase complex with Cul3 and Rbx1, facilitates ubiquitination and degradation of IκB kinase (IKK)-β thus terminating IKK activity. Keap1 knockdown led to increased nuclear translocation of transcription factors NF-κB, IFN regulatory factor (IRF) 1, and IRF5 driving the expression of inflammatory cytokines and IFN-β. Furthermore, knockdown of other members of the Cul3 ubiquitin ligase complex also led to increased cytokine expression, further implicating this ligase complex in the regulation of the IKK family. Finally, increased inflammatory responses in Keap1-silenced cells contributed to decreased intracellular growth of M. avium in primary human macrophages that was reconstituted with inhibitors of IKKβ or TANK-binding kinase 1 (TBK1). Taken together, we propose that Keap1 acts as a negative regulator for the control of inflammatory signaling in M. avium-infected human primary macrophages. Although this might be important to avoid sustained or overwhelming inflammation, our data suggest that a negative consequence could be facilitated growth of pathogens like M. avium inside macrophages.Keap1 | human primary macrophages | infection | Mycobacterium avium | inflammation

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Section: Discussionmentioning

confidence: 55%

Keap1 regulates inflammatory signaling in Mycobacterium avium -infected human macrophages

Awuh

Haug

Mildenberger

et al. 2015

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

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“…These results are sustained by the presence of a NF-B binding site in the Nrf2 gene (42) (Fig. 8B) and by the fact that IK-␤ (IB␣ kinase) contains an ETGE motif that enables it to bind to KEAP1 (43,44). Also, NRF2 deficiency results in increased ROS levels, which induce IB␣ phosphorylation and subsequent degradation, increasing p65-NF-B levels and NF-B proinflammatory processes (Fig.…”

Section: Discussionmentioning

confidence: 93%

Transcription Factors NRF2 and NF-κB Are Coordinated Effectors of the Rho Family, GTP-binding Protein RAC1 during Inflammation

Cuadrado

Martín‐Moldes

et al. 2014

Journal of Biological Chemistry

280

186

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Background: RAC1 is a small G-protein of the Rho family that activates the transcription factor NF-B to elicit an inflammatory response. Results: We have found that RAC1 also induces the NRF2/ARE pathway, which in term blocks RAC1-dependent NF-B activation. Conclusion: RAC1 modulates inflammation by coordinating the activity of pro-inflammatory NF-B and anti-oxidant NRF2 transcription factors. Significance: Therapeutic intervention on RAC1 could help modulate pro-and anti-inflammatory processes.

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“…Phosphoglycerate mutase 5 (PGAM5) may also be degraded in a Keap1-dependent fashion [282], as may inhibitor of κB kinase β (IKKβ) [283, 284]. In the former case, PGAM5, a serine–threonine phosphatase known to activate ASK1 [285], contains a conserved N-terminal ESGE motif, which binds to Keap1 in a manner similar to that of the Nrf2 ETGE motif.…”

Section: Molecular Regulation Of Nrf2mentioning

confidence: 99%

Mechanisms of activation of the transcription factor Nrf2 by redox stressors, nutrient cues, and energy status and the pathways through which it attenuates degenerative disease

Tebay

Robertson

Durant

et al. 2015

Free Radical Biology and Medicine

711

604

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Nuclear factor-erythroid 2 p45-related factor 2 (Nrf2) regulates the basal and stress-inducible expression of a battery of genes encoding key components of the glutathione-based and thioredoxin-based anti-oxidant systems, as well as aldo-keto reductase, glutathione S-transferase, and NAD(P)H:quinone oxi-doreductase-1 drug-metabolizing isoenzymes along with multidrug-resistance-associated efflux pumps. It therefore plays a pivotal role in both intrinsic resistance and cellular adaptation to reactive oxygen species (ROS) and xenobiotics. Activation of Nrf2 can, however, serve as a double-edged sword because some of the genes it induces may contribute to chemical carcinogenesis by promoting futile redox cycling of polycyclic aromatic hydrocarbon metabolites or confer resistance to chemotherapeutic drugs by increasing the expression of efflux pumps, suggesting its cytoprotective effects will vary in a context-specific fashion. In addition to cytoprotection, Nrf2 also controls genes involved in intermediary metabolism, positively regulating those involved in NADPH generation, purine biosynthesis, and the β-oxidation of fatty acids, while suppressing those involved in lipogenesis and gluconeogenesis. Nrf2 is subject to regulation at multiple levels. Its ability to orchestrate adaptation to oxidants and electrophiles is due principally to stress-stimulated modification of thiols within one of its repressors, the Kelch-like ECH-associated protein 1 (Keap1), which is present in the cullin-3 RING ubiquitin ligase (CRL) complex CRLKeap1. Thus modification of Cys residues in Keap1 blocks CRLKeap1 activity, allowing newly translated Nrf2 to accumulate rapidly and induce its target genes. The ability of Keap1 to repress Nrf2 can be attenuated by p62/sequestosome-1 in a mechanistic target of rapamycin complex 1 (mTORC1)-depen-dent manner, thereby allowing refeeding after fasting to increase Nrf2-target gene expression. In parallel with repression by Keap1, Nrf2 is also repressed by β-transducin repeat-containing protein (β-TrCP), present in the Skp1–cullin-1–F-box protein (SCF) ubiquitin ligase complex SCFβ-TrCP. The ability of SCFβ-TrCP to suppress Nrf2 activity is itself enhanced by prior phosphorylation of the transcription factor by glycogen synthase kinase-3 (GSK-3) through formation of a DSGIS-containing phosphodegron. However, formation of the phosphodegron in Nrf2 by GSK-3 is inhibited by stimuli that activate protein kinase B (PKB)/Akt. In particular, PKB/Akt activity can be increased by phosphoinositide 3-kinase and mTORC2, thereby providing an explanation of why antioxidant-responsive element-driven genes are induced by growth factors and nutrients. Thus Nrf2 activity is tightly controlled via CRLKeap1 and SCFβ-TrCP by oxidative stress and energy-based signals, allowing it to mediate adaptive responses that restore redox homeostasis and modulate intermediary metabolism. Based on the fact that Nrf2 influences multiple biochemical pathways in both positive and negative ways, it is likely its dose–response curve, in te...

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Insight into the Intermolecular Recognition Mechanism between Keap1 and IKKβ Combining Homology Modelling, Protein-Protein Docking, Molecular Dynamics Simulations and Virtual Alanine Mutation

Cited by 43 publications

References 67 publications

Keap1 regulates inflammatory signaling in Mycobacterium avium -infected human macrophages

Keap1 regulates inflammatory signaling in Mycobacterium avium -infected human macrophages

Transcription Factors NRF2 and NF-κB Are Coordinated Effectors of the Rho Family, GTP-binding Protein RAC1 during Inflammation

Mechanisms of activation of the transcription factor Nrf2 by redox stressors, nutrient cues, and energy status and the pathways through which it attenuates degenerative disease

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