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1. A catalogue of somatic NRF2 gain-of-function mutations in cancer

   https://doi.org/10.1038/s41598-018-31281-0  

   Kerins, Michael John ; Ooi, Aikseng ( August 2018 , Scientific Reports)

   Identification and characterization of somatic mutations in cancer have important prognostication and treatment implications. Genes encoding the Nuclear factor (erythroid-derived 2)-like 2 (NRF2) transcription factor and its negative regulator, Kelch-like ECH-associated protein 1 (KEAP1), are frequently mutated in cancer. These mutations drive constitutive NRF2 activation and correlate with poor prognosis. Despite its apparent significance, a comprehensive catalogue of somatic NRF2 mutations across different tumor types is still lacking. Here, we catalogue NRF2 mutations in The Cancer Genome Atlas (TCGA) database. 226 unique NRF2-mutant tumors were identified from 10,364 cases. NRF2 mutations were found in 21 out of the 33 tumor types. A total of 11 hotspots were identified. Of these, mutation to the R34 position was most frequent. Notably, R34 and D29 mutations were overrepresented in bladder, lung, and uterine cancers. Analyses of corresponding RNA sequencing data using a de novo derived gene expression classifier showed that the R34 mutations drive constitutive NRF2 activation with a selection pressure biased against the formation of R34L. Of all R34 mutants, R34L conferred the least degree of protein stabilization, suggesting a pro-tumor NRF2 half-life threshold. Our findings offer a comprehensive catalogue of NRF2 mutations in cancer that can help prognostication and NRF2 research.

    

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2. Sulforaphane prevents age‐associated cardiac and muscular dysfunction through Nrf2 signaling

   https://doi.org/10.1111/acel.13261  

   Bose, Chhanda ; Alves, Ines ; Singh, Preeti ; Palade, Philip T. ; Carvalho, Eugenia ; Børsheim, Elisabet ; Jun, Se‐Ran ; Cheema, Amrita ; Boerma, Marjan ; Awasthi, Sanjay ; et al ( November 2020 , Aging Cell)

   Age‐associated mitochondrial dysfunction and oxidative damage are primary causes for multiple health problems including sarcopenia and cardiovascular disease (CVD). Though the role of Nrf2, a transcription factor that regulates cytoprotective gene expression, in myopathy remains poorly defined, it has shown beneficial properties in both sarcopenia and CVD. Sulforaphane (SFN), a natural compound Nrf2‐related activator of cytoprotective genes, provides protection in several disease states including CVD and is in various stages of clinical trials, from cancer prevention to reducing insulin resistance. This study aimed to determine whether SFN may prevent age‐related loss of function in the heart and skeletal muscle. Cohorts of 2‐month‐old and 21‐ to 22‐month‐old mice were administered regular rodent diet or diet supplemented with SFN for 12 weeks. At the completion of the study, skeletal muscle and heart function, mitochondrial function, and Nrf2 activity were measured. Our studies revealed a significant drop in Nrf2 activity and mitochondrial functions, together with a loss of skeletal muscle and cardiac function in the old control mice compared to the younger age group. In the old mice, SFN restored Nrf2 activity, mitochondrial function, cardiac function, exercise capacity, glucose tolerance, and activation/differentiation of skeletal muscle satellite cells. Our results suggest that the age‐associated decline in Nrf2 signaling activity and the associated mitochondrial dysfunction might be implicated in the development of age‐related disease processes. Therefore, the restoration of Nrf2 activity and endogenous cytoprotective mechanisms by SFN may be a safe and effective strategy to protect against muscle and heart dysfunction due to aging.

    

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3. Inhibiting the Keap1/Nrf2 Protein‐Protein Interaction with Protein‐Like Polymers

   https://doi.org/10.1002/adma.202311467  

   Carrow, Kendal P. ; Hamilton, Haylee L. ; Hopps, Madeline P. ; Li, Yang ; Qiao, Baofu ; Payne, N. Connor ; Thompson, Matthew P. ; Zhang, Xiaoyu ; Magassa, Assa ; Fattah, Mara ; et al ( February 2024 , Advanced Materials)

   Successful and selective inhibition of the cytosolic protein‐protein interaction (PPI) between nuclear factor erythroid 2‐related factor 2 (Nrf2) and Kelch‐like ECH‐associating protein 1 (Keap1) can enhance the antioxidant response, with the potential for a therapeutic effect in a range of settings including in neurodegenerative disease (ND). Small molecule inhibitors have been developed, yet many have off‐target effects, or are otherwise limited by poor cellular permeability. Peptide‐based strategies have also been attempted to enhance specificity, yet face challenges due to susceptibility to degradation and lack of cellular penetration. Herein, these barriers are overcome utilizing a polymer‐based proteomimetics. The protein‐like polymer (PLP) consists of a synthetic, lipophilic polymer backbone displaying water soluble Keap1‐binding peptides on each monomer unit forming a brush polymer architecture. The PLPs are capable of engaging Keap1 and displacing the cellular protective transcription factor Nrf2, which then translocates to the nucleus, activating the antioxidant response element (ARE). PLPs exhibit increased Keap1 binding affinity by several orders of magnitude compared to free peptides, maintain serum stability, are cell‐penetrant, and selectively activate the ARE pathway in cells, including in primary cortical neuronal cultures. Keap1/Nrf2‐inhibitory PLPs have the potential to impact the treatment of disease states associated with dysregulation of oxidative stress, such as NDs.

    

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4. Flight and Dietary Antioxidants Influence Antioxidant Expression and Activity in a Migratory Bird

   https://doi.org/10.1093/iob/obab035  

   DeMoranville, Kristen J. ; Carter, Wales A. ; Pierce, Barbara J. ; McWilliams, Scott R. ( December 2021 , Integrative Organismal Biology)

   Ecologically relevant factors such as exercise and diet quality can directly influence how physiological systems work including those involved in maintaining oxidative balance; however, to our knowledge, no studies to date have focused on how such factors directly affect expression of key components of the endogenous antioxidant system (i.e., transcription factors, select antioxidant genes, and corresponding antioxidant enzymes) in several metabolically active tissues of a migratory songbird. We conducted a three-factor experiment that tested the following hypotheses: (H1) Daily flying over several weeks increases the expression of transcription factors NRF2 and PPARs as well as endogenous antioxidant genes (i.e., CAT, SOD1, SOD2, GPX1, GPX4), and upregulates endogenous antioxidant enzyme activities (i.e., CAT, SOD, GPx). (H2) Songbirds fed diets composed of more 18:2n-6 PUFA are more susceptible to oxidative damage and thus upregulate their endogenous antioxidant system compared with when fed diets with less PUFA. (H3) Songbirds fed dietary anthocyanins gain additional antioxidant protection and thus upregulate their endogenous antioxidant system less compared with songbirds not fed anthocyanins. Flight training increased the expression of 3 of the 6 antioxidant genes and transcription factors measured in the liver, consistent with H1, but for only one gene (SOD2) in the pectoralis. Dietary fat quality had no effect on antioxidant pathways (H2), whereas dietary anthocyanins increased the expression of select antioxidant enzymes in the pectoralis, but not in the liver (H3). These tissue-specific differences in response to flying and dietary antioxidants are likely explained by functional differences between tissues as well as fundamental differences in their turnover rates. The consumption of dietary antioxidants along with regular flying enables birds during migration to stimulate the expression of genes involved in antioxidant protection likely through increasing the transcriptional activity of NRF2 and PPARs, and thereby demonstrates for the first time that these relevant ecological factors affect the regulation of key antioxidant pathways in wild birds. What remains to be demonstrated is how the extent of these ecological factors (i.e., intensity or duration of flight, amounts of dietary antioxidants) influences the regulation of these antioxidant pathways and thus oxidative balance.

    

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5. Activation of PERK-Nrf2 oncogenic signaling promotes Mdm2-mediated Rb degradation in persistently infected HCV culture

   https://doi.org/10.1038/s41598-017-10087-6  

   Aydin, Yucel ; Chedid, Milad ; Chava, Srinivas ; Danielle Williams, Donkita ; Liu, Shuanghu ; Hagedorn, Curt H. ; Sumitran-Holgersson, Suchitra ; Reiss, Krzysztof ; Moroz, Krzysztof ; Lu, Hua ; et al ( December 2017 , Scientific Reports)

   null (Ed.)

   Abstract The mechanism of how chronic hepatitis C virus (HCV) infection leads to such a high rate of hepatocellular carcinoma (HCC) is unknown. We found that the PERK axis of endoplasmic reticulum (ER) stress elicited prominent nuclear translocation of Nrf2 in 100% of HCV infected hepatocytes. The sustained nuclear translocation of Nrf2 in chronically infected culture induces Mdm2-mediated retinoblastoma protein (Rb) degradation. Silencing PERK and Nrf2 restored Mdm2-mediated Rb degradation, suggesting that sustained activation of PERK/Nrf2 axis creates oncogenic stress in chronically infected HCV culture model. The activation of Nrf2 and its nuclear translocation were prevented by ER-stress and PERK inhibitors, suggesting that PERK axis is involved in the sustained activation of Nrf2 signaling during chronic HCV infection. Furthermore, we show that HCV clearance induced by interferon-α based antiviral normalized the ER-stress response and prevented nuclear translocation of Nrf2, whereas HCV clearance by DAAs combination does neither. In conclusion, we report here a novel mechanism for how sustained activation of PERK axis of ER-stress during chronic HCV infection activates oncogenic Nrf2 signaling that promotes hepatocyte survival and oncogenesis by inducing Mdm2-mediated Rb degradation. 

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