Cited by 58Genomics, phytochemicals, and oxidative stressMuscle Physiology and DisordersRedox biology and oxidative stress

Functional, proteomic and bioinformatic analyses of Nrf2- and Keap1- null skeletal muscle

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Gao, Lie, Kumar, Vikas, Vellichirammal, Neetha Nanoth, Park, Song‐Young, Rudebush, Tara L., Yu, Li, Son, Won‐Mok, Pekas, Elizabeth J. +7 more·2020·The Journal of Physiology

Abstract

Key points: Nrf2 is a master regulator of endogenous cellular defences, governing the expression of more than 200 cytoprotective proteins, including a panel of antioxidant enzymes. Nrf2 plays an important role in redox haemostasis of skeletal muscle in response to the increased generation of reactive oxygen species during contraction. Employing skeletal muscle‐specific transgenic mouse models with unbiased‐omic approaches, we uncovered new target proteins, downstream pathways and molecular networks of Nrf2 in skeletal muscle following Nrf2 or Keap1 deletion. Based on the findings, we proposed a two‐way model to understand Nrf2 function: a tonic effect through a Keap1‐independent mechanism under basal conditions and an induced effect through a Keap1‐dependent mechanism in response to oxidative and other stresses. Although Nrf2 has been recognized as a master regulator of cytoprotection, its functional significance remains to be completely defined. We hypothesized that proteomic/bioinformatic analyses from Nrf2‐deficient or overexpressed skeletal muscle tissues will provide a broader spectrum of Nrf2 targets and downstream pathways than are currently known. To this end, we created two transgenic mouse models; the iMS‐Nrf2 flox/flox and iMS‐Keap1 flox/flox, employing which we demonstrated that selective deletion of skeletal muscle Nrf2 or Keap1 separately impaired or improved skeletal muscle function. Mass spectrometry revealed that Nrf2‐KO changed expression of 114 proteins while Keap1‐KO changed expression of 117 proteins with 10 proteins in common between the groups. Gene ontology analysis suggested that Nrf2 KO‐changed proteins are involved in metabolism of oxidoreduction coenzymes, purine ribonucleoside triphosphate, ATP and propanoate, which are considered as the basal function of Nrf2, while Keap1 KO‐changed proteins are involved in cellular detoxification, NADP metabolism, glutathione metabolism and the electron transport chain, which belong to the induced effect of Nrf2. Canonical pathway analysis suggested that Keap1‐KO activated four pathways, whereas Nrf2‐KO did not. Ingenuity pathway analysis further revealed that Nrf2‐KO and Keap1‐KO impacted different signal proteins and functions. Finally, we validated the proteomic and bioinformatics data by analysing glutathione metabolism and mitochondrial function. In conclusion, we found that Nrf2‐targeted proteins are assigned to two groups: one mediates the tonic effects evoked by a low level of Nrf2 at basal condition; the other is responsible for the inducible effects evoked by a surge of Nrf2 that is dependent on a Keap1 mechanism.

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  • Formate triggered upregulation of differentially expressed genes involved in one-carbon metabolism (Shmt2, Cth) and Nrf2-regulated genes (Cth, mt-Nd4, Tkt).

    “formate triggered an upregulation of differentially expressed genes (DEGs) involved in 1C metabolism, such as serine hydroxymethyltransferase 2 (Shmt2)42,58 and cystathionine gamma-lyase (Cth)59, as well as genes regulated by Nrf2 (e.g.: Cth60, NADH dehydrogenase 4 (mt-Nd4)61 and transketolase (Tkt)62,63) (Figure 6L and Table S3).”

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Authors
Gao, L., Kumar, V., Vellichirammal, N. N., Park, S., Rudebush, T. L., Yu, L., Son, W., Pekas, E. J., Wafi, A. M., Hong, J., Xiao, P., Guda, C., Wang, H., Schultz, H. D., & Zucker, I. H.
Affiliations
  • University of Nebraska Medical Center (US)
  • University of Nebraska at Omaha (US)
  • Department of Anesthesiology University of Nebraska Medical Center Omaha NE USA
Corresponding author
  • Gao, Lie
  • Zucker, Irving H.
Venue
The Journal of Physiology
Publisher
Wiley
Published
2020-09-23
Volume
598
Issue
23
Pages
5427-5451
ISSN
  • 0022-3751 (ISSN-L)
  • 1469-7793
OpenAlex
W3122044228
Cited by
58
References
69
Citations by year
2026: 4 · 2025: 14 · 2024: 12 · 2023: 10 · 2022: 9 · 2021: 8 · 2020: 1
FWCI
2.27
Type
journal article
Language
en
Open access
Locations
  • The Journal of Physiology (publishedVersion)
  • PubMed (publishedVersion)
  • PubMed Central (acceptedVersion)
  • DigitalCommons@UNO (submittedVersion)
Funders
National Institutes of Health (P01 HL62222, P20GM103427, P30CA036727)
Topics
  • Life Sciences › Biochemistry, Genetics and Molecular Biology › Molecular Biology › Genomics, phytochemicals, and oxidative stress
  • Life Sciences › Biochemistry, Genetics and Molecular Biology › Molecular Biology › Muscle Physiology and Disorders
  • Life Sciences › Biochemistry, Genetics and Molecular Biology › Molecular Biology › Redox biology and oxidative stress
Keywords
Nrf2, Keap1, skeletal muscle, oxidative stress, reactive oxygen species, glutathione metabolism, mitochondrial function, purine metabolism, electron transport chain, skeletal muscle function, transgenic mouse model, proteomics, bioinformatics
MeSH terms
Kelch-Like ECH-Associated Protein 1, Animals, Oxidative Stress, Muscle, Skeletal, Computational Biology, Proteomics, NF-E2-Related Factor 2, Mice

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