Transcription factors NRF2 and NF-κB are coordinated effectors of the Rho family, GTP-binding protein RAC1 during inflammation.
The small GTPase protein RAC1 participates in innate immunity by activating a complex program that includes cytoskeleton remodeling, chemotaxis, activation of NADPH oxidase, and modulation of gene expression. However, its role in regulating the transcriptional signatures that in term control the cellular inflammatory profiles are not well defined. Here we investigated the functional and mechanistic connection between RAC1 and the transcription factor NRF2 (nuclear factor erythroid 2-related factor 2), master regulator of the anti-oxidant response. Lipopolysaccharide and constitutively active RAC1(Q61L) mutant induced the anti-oxidant enzyme heme-oxygenase-1 (HO-1) through activation of NRF2. The use of KEAP1-insensitive NRF2 mutants indicated that RAC1 regulation of NRF2 is KEAP1-independent. Interestingly, NRF2 overexpression inhibited, whereas a dominant-negative mutant of NRF2 exacerbated RAC1-dependent activation of nuclear factor-κB (NF-κB), suggesting that NRF2 has an antagonistic effect on the NF-κB pathway. Moreover, we found that RAC1 acts through NF-κB to induce NRF2 because either expression of a dominant negative mutant of IκBα that leads to NF-κB degradation or the use of p65-NF-κB-deficient cells demonstrated lower NRF2 protein levels and basally impaired NRF2 signature compared with control cells. In contrast, NRF2-deficient cells showed increased p65-NF-κB protein levels, although the mRNA levels remain unchanged, indicating post-translational alterations. Our results demonstrate a new mechanism of modulation of RAC1 inflammatory pathway through a cross-talk between NF-κB and NRF2.
From the Centro de Investigación Biomédica en Red sobre Enfermedades Neurodegenerativas (CIBERNED), Instituto de Investigación Sanitaria La Paz (IdiPAZ), Departamento de Bioquímica e Instituto de Investigaciones Biomédicas "Alberto Sols" CSIC-UAM, Facultad de Medicina, Universidad Autónoma de Madrid, 28029 Madrid, Spain.
Antonio
A
Cuadrado
From the Centro de Investigación Biomédica en Red sobre Enfermedades Neurodegenerativas (CIBERNED), Instituto de Investigación Sanitaria La Paz (IdiPAZ), Departamento de Bioquímica e Instituto de Investigaciones Biomédicas "Alberto Sols" CSIC-UAM, Facultad de Medicina, Universidad Autónoma de Madrid, 28029 Madrid, Spain, Department of Environmental Biology, Centro de Investigaciones Biológicas, Consejo Superior de Investigaciones Científicas, 28040 Madrid, Spain, and.
Zaira
Z
Martín-Moldes
Pennington Biomedical Research Center, Louisiana State University, Baton Rouge, Louisianna 70808.
Jianping
J
Ye
From the Centro de Investigación Biomédica en Red sobre Enfermedades Neurodegenerativas (CIBERNED), Instituto de Investigación Sanitaria La Paz (IdiPAZ), Departamento de Bioquímica e Instituto de Investigaciones Biomédicas "Alberto Sols" CSIC-UAM, Facultad de Medicina, Universidad Autónoma de Madrid, 28029 Madrid, Spain, ilbecker@iib.uam.es.
Isabel
I
Lastres-Becker
D006160:Guanosine Triphosphate / Q000378:metabolism; D057809:HEK293 Cells; D051547:Heme Oxygenase-1 / Q000235:genetics / Q000276:immunology / Q000378:metabolism; D006801:Humans; D007249:Inflammation / Q000235:genetics / Q000378:metabolism*; D008070:Lipopolysaccharides / Q000494:pharmacology; D017628:Microglia / Q000187:drug effects / Q000276:immunology* / Q000378:metabolism; D051267:NF-E2-Related Factor 2 / Q000235:genetics / Q000276:immunology / Q000378:metabolism*; D016328:NF-kappa B / Q000235:genetics / Q000276:immunology / Q000378:metabolism*; D018384:Oxidative Stress / Q000276:immunology; D017382:Reactive Oxygen Species / Q000378:metabolism; D020830:rac1 GTP-Binding Protein / Q000235:genetics / Q000276:immunology* / Q000378:metabolism; D020741:rho GTP-Binding Proteins / Q000235:genetics / Q000276:immunology / Q000378:metabolism
D008070:Lipopolysaccharides; D051267:NF-E2-Related Factor 2; D016328:NF-kappa B; C495635:NFE2L2 protein, human; C107953:RAC1 protein, human; D017382:Reactive Oxygen Species; D006160:Guanosine Triphosphate; C496541:HMOX1 protein, human; D051547:Heme Oxygenase-1; D020830:rac1 GTP-Binding Protein; D020741:rho GTP-Binding Proteins
Inflammation; Lipopolysaccharide (LPS); Microglia; NF-κ B (NF-KB); Nuclear Factor 2 (Erythroid-derived 2-like Factor) (NFE2L2) (Nrf2); Oxidative Stress; Ras-related C3 Botulinum Toxin Substrate 1 (Rac1); Rho GTPases