Specific targeting of the NRF2/ß-TrCP axis promotes beneficial effects in NASH.

Non-alcoholic steatohepatitis (NASH) is a common chronic liver disease that compromises liver function, for which there is not a specifically approved medicine. Recent research has identified transcription factor NRF2 as a potential therapeutic target. However, current NRF2 activators, designed to inhibit its repressor KEAP1, exhibit unwanted side effects. Alternatively, we previously introduced PHAR, a protein-protein interaction inhibitor of NRF2/ß-TrCP, which induces a mild NRF2 activation and selectively activates NRF2 in the liver, close to normal physiological levels. Herein, we assessed the effect of PHAR in protection against NASH and its progression to fibrosis. We conducted experiments to demonstrate that PHAR effectively activated NRF2 in hepatocytes, Kupffer cells, and stellate cells. Then, we used the STAM mouse model of NASH, based on partial damage of endocrine pancreas and insulin secretion impairment, followed by a high fat diet. Non-invasive analysis using MRI revealed that PHAR protects against liver fat accumulation. Moreover, PHAR attenuated key markers of NASH progression, including liver steatosis, hepatocellular ballooning, inflammation, and fibrosis. Notably, transcriptomic data indicate that PHAR led to upregulation of 3 anti-fibrotic genes (Plg, Serpina1a, and Bmp7) and downregulation of 6 pro-fibrotic (including Acta2 and Col3a1), 11 extracellular matrix remodeling, and 8 inflammatory genes. Overall, our study suggests that the mild activation of NRF2 via the protein-protein interaction inhibitor PHAR holds promise as a strategy for addressing NASH and its progression to liver fibrosis.

Dipeptide Repeat Pathology in C9orf72-ALS Is Associated with Redox, Mitochondrial and NRF2 Pathway Imbalance.

The hexanucleotide expansion of the C9orf72 gene is found in 40% of familial amyotrophic lateral sclerosis (ALS) patients. This genetic alteration has been connected with impaired management of reactive oxygen species. In this study, we conducted targeted transcriptional profiling in leukocytes from C9orf72 patients and control subjects by examining the mRNA levels of 84 redox-related genes. The expression of ten redox genes was altered in samples from C9orf72 ALS patients compared to healthy controls. Considering that Nuclear factor erythroid 2-Related Factor 2 (NRF2) modulates the expression of a wide range of redox genes, we further investigated its status on an in vitro model of dipeptide repeat (DPR) toxicity. This model mimics the gain of function, toxic mechanisms attributed to C9orf72 pathology. We found that exposure to DPRs increased superoxide levels and reduced mitochondrial potential as well as cell survival. Importantly, cells overexpressing DPRs exhibited reduced protein levels of NRF2 and its target genes upon inhibition of the proteasome or its canonical repressor, the E3 ligase adapter KEAP1. However, NRF2 activation was sufficient to recover cell viability and redox homeostasis. This study identifies NRF2 as a putative target in precision medicine for the therapy of ALS patients harboring C9orf72 expansion repeats.

An inhibitor of interaction between the transcription factor NRF2 and the E3 ubiquitin ligase adapter ß-TrCP delivers anti-inflammatory responses in mouse liver.

It is widely accepted that activating the transcription factor NRF2 will blast the physiological anti-inflammatory mechanisms, which will help combat pathologic inflammation. Much effort is being put in inhibiting the main NRF2 repressor, KEAP1, with either electrophilic small molecules or disrupters of the KEAP1/NRF2 interaction. However, targeting ß-TrCP, the non-canonical repressor of NRF2, has not been considered yet. After in silico screening of ∼1 million compounds, we now describe a novel small molecule, PHAR, that selectively inhibits the interaction between ß-TrCP and the phosphodegron in transcription factor NRF2. PHAR upregulates NRF2-target genes such as Hmox1, Nqo1, Gclc, Gclm and Aox1, in a KEAP1-independent, but ß-TrCP dependent manner, breaks the ß-TrCP/NRF2 interaction in the cell nucleus, and inhibits the ß-TrCP-mediated in vitro ubiquitination of NRF2. PHAR attenuates hydrogen peroxide induced oxidative stress and, in lipopolysaccharide-treated macrophages, it downregulates the expression of inflammatory genes Il1b, Il6, Cox2, Nos2. In mice, PHAR selectively targets the liver and greatly attenuates LPS-induced liver inflammation as indicated by a reduction in the gene expression of the inflammatory cytokines Il1b, TNf, and Il6, and in F4/80-stained liver resident macrophages. Thus, PHAR offers a still unexplored alternative to current NRF2 activators by acting as a ß-TrCP/NRF2 interaction inhibitor that may have a therapeutic value against undesirable inflammation.

Whole Blood Expression Pattern of Inflammation and Redox Genes in Mild Alzheimer's Disease.

BACKGROUND: Although Alzheimer's disease (AD) is associated with alterations of the central nervous system, this disease has an echo in blood that might represent a valuable source of biomarkers for improved diagnosis, prognosis and for monitoring drug response. METHODS: We performed a targeted transcriptomics study on 38 mild Alzheimer's disease (AD) patients and 38 matched controls for evaluating the expression levels of 136 inflammation and 84 redox genes in whole blood. Patients were diagnosed as mild AD based on altered levels of total TAU, phospho-TAU and Abeta(1-42) in cerebrospinal fluid, and Abeta(1-40), Abeta(1-42) and total TAU levels in plasma. Whenever possible, blood and brain comparisons were made using public datasets. RESULTS: We found 48 inflammation and 34 redox genes differentially expressed in the blood of AD patients vs controls (FC >1.5, p < 0.01), out of which 22 pro-inflammatory and 12 redox genes exhibited FC >2 and p < 0.001. Receiver operating characteristic (ROC) analysis identified nine inflammation and seven redox genes that discriminated between AD patients and controls (area under the curve >0.9). Correlations of the dysregulated inflammation and redox transcripts indicated that RELA may regulate several redox genes including DUOX1 and GSR. Based on the gene expression profile, we have found that the master regulators of inflammation and redox homeostasis, NFκB and NRF2, were significantly disturbed in the blood of AD patients, as well as several zinc finger and helix-loop-helix transcription factors. CONCLUSION: The selected inflammation and redox genes might be useful biomarkers for monitoring anti-inflammatory therapy in mild AD.

On the Clinical Pharmacology of Reactive Oxygen Species.

Reactive oxygen species (ROS) have been correlated with almost every human disease. Yet clinical exploitation of these hypotheses by pharmacological modulation of ROS has been scarce to nonexistent. Are ROS, thus, irrelevant for disease? No. One key misconception in the ROS field has been its consideration as a rather detrimental metabolic by-product of cell metabolism, and thus, any approach eliminating ROS to a certain tolerable level would be beneficial. We now know, instead, that ROS at every concentration, low or high, can serve many essential signaling and metabolic functions. This likely explains why systemic, nonspecific antioxidants have failed in the clinic, often with neutral and sometimes even detrimental outcomes. Recently, drug development has focused, instead, on identifying and selectively modulating ROS enzymatic sources that in a given constellation cause disease while leaving ROS physiologic signaling and metabolic functions intact. As sources, the family of NADPH oxidases stands out as the only enzyme family solely dedicated to ROS formation. Selectively targeting disease-relevant ROS-related proteins is already quite advanced, as evidenced by several phase II/III clinical trials and the first drugs having passed registration. The ROS field is expanding by including target enzymes and maturing to resemble more and more modern, big data-enhanced drug discovery and development, including network pharmacology. By defining a disease based on a distinct mechanism, in this case ROS dysregulation, and not by a symptom or phenotype anymore, ROS pharmacology is leaping forward from a clinical underperformer to a proof of concept within the new era of mechanism-based precision medicine. SIGNIFICANCE STATEMENT: Despite being correlated to almost every human disease, nearly no ROS modulator has been translated to the clinics yet. Here, we move far beyond the old-fashioned misconception of ROS as detrimental metabolic by-products and suggest 1) novel pharmacological targeting focused on selective modulation of ROS enzymatic sources, 2) mechanism-based redefinition of diseases, and 3) network pharmacology within the ROS field, altogether toward the new era of ROS pharmacology in precision medicine.

Can Activation of NRF2 Be a Strategy against COVID-19?

Acute respiratory distress syndrome (ARDS) caused by SARS-CoV-2 is largely the result of a dysregulated host response, followed by damage to alveolar cells and lung fibrosis. Exacerbated proinflammatory cytokines release (cytokine storm) and loss of T lymphocytes (leukopenia) characterize the most aggressive presentation. We propose that a multifaceted anti-inflammatory strategy based on pharmacological activation of nuclear factor erythroid 2 p45-related factor 2 (NRF2) can be deployed against the virus. The strategy provides robust cytoprotection by restoring redox and protein homeostasis, promoting resolution of inflammation, and facilitating repair. NRF2 activators such as sulforaphane and bardoxolone methyl are already in clinical trials. The safety and efficacy information of these modulators in humans, together with their well-documented cytoprotective and anti-inflammatory effects in preclinical models, highlight the potential of this armamentarium for deployment to the battlefield against COVID-19.

Nordihydroguaiaretic Acid: From Herbal Medicine to Clinical Development for Cancer and Chronic Diseases.

Nordihydroguaiaretic acid (NDGA) is a phenolic lignan obtained from Larrea tridentata, the creosote bush found in Mexico and USA deserts, that has been used in traditional medicine for the treatment of numerous diseases such as cancer, renal, cardiovascular, immunological, and neurological disorders, and even aging. NDGA presents two catechol rings that confer a very potent antioxidant activity by scavenging oxygen free radicals and this may explain part of its therapeutic action. Additional effects include inhibition of lipoxygenases (LOXs) and activation of signaling pathways that impinge on the transcription factor Nuclear Factor Erythroid 2-related Factor (NRF2). On the other hand, the oxidation of the catechols to the corresponding quinones my elicit alterations in proteins and DNA that raise safety concerns. This review describes the current knowledge on NDGA, its targets and side effects, and its synthetic analogs as promising therapeutic agents, highlighting their mechanism of action and clinical projection towards therapy of neurodegenerative, liver, and kidney disease, as well as cancer.

Transcription factor NRF2 uses the Hippo pathway effector TAZ to induce tumorigenesis in glioblastomas.

Transcription factor NRF2 orchestrates a cellular defense against oxidative stress and, so far, has been involved in tumor progression by providing a metabolic adaptation to tumorigenic demands and resistance to chemotherapeutics. In this study, we discover that NRF2 also propels tumorigenesis in gliomas and glioblastomas by inducing the expression of the transcriptional co-activator TAZ, a protein of the Hippo signaling pathway that promotes tumor growth. The expression of the genes encoding NRF2 (NFE2L2) and TAZ (WWTR1) showed a positive correlation in 721 gliomas from The Cancer Genome Atlas database. Moreover, NRF2 and TAZ protein levels also correlated in immunohistochemical tissue arrays of glioblastomas. Genetic knock-down of NRF2 decreased, while NRF2 overexpression or chemical activation with sulforaphane, increased TAZ transcript and protein levels. Mechanistically, we identified several NRF2-regulated functional enhancers in the regulatory region of WWTR1. The relevance of the new NRF2/TAZ axis in tumorigenesis was demonstrated in subcutaneous and intracranial grafts. Thus, intracranial inoculation of NRF2-depleted glioma stem cells did not develop tumors as determined by magnetic resonance imaging. Forced TAZ overexpression partly rescued both stem cell growth in neurospheres and tumorigenicity. Hence, NRF2 not only enables tumor cells to be competent to proliferate but it also propels tumorigenesis by activating the TAZ-mediated Hippo transcriptional program.

Therapeutic targeting of the NRF2 and KEAP1 partnership in chronic diseases.

The transcription factor NF-E2 p45-related factor 2 (NRF2; encoded by NFE2L2) and its principal negative regulator, the E3 ligase adaptor Kelch-like ECH-associated protein 1 (KEAP1), are critical in the maintenance of redox, metabolic and protein homeostasis, as well as the regulation of inflammation. Thus, NRF2 activation provides cytoprotection against numerous pathologies including chronic diseases of the lung and liver; autoimmune, neurodegenerative and metabolic disorders; and cancer initiation. One NRF2 activator has received clinical approval and several electrophilic modifiers of the cysteine-based sensor KEAP1 and inhibitors of its interaction with NRF2 are now in clinical development. However, challenges regarding target specificity, pharmacodynamic properties, efficacy and safety remain.

A role for APP in Wnt signalling links synapse loss with ß-amyloid production.

In Alzheimer's disease (AD), the canonical Wnt inhibitor Dickkopf-1 (Dkk1) is induced by ß-amyloid (Aß) and shifts the balance from canonical towards non-canonical Wnt signalling. Canonical (Wnt-ß-catenin) signalling promotes synapse stability, while non-canonical (Wnt-PCP) signalling favours synapse retraction; thus Aß-driven synapse loss is mediated by Dkk1. Here we show that the Amyloid Precursor Protein (APP) co-activates both arms of Wnt signalling through physical interactions with Wnt co-receptors LRP6 and Vangl2, to bi-directionally modulate synapse stability. Furthermore, activation of non-canonical Wnt signalling enhances Aß production, while activation of canonical signalling suppresses Aß production. Together, these findings identify a pathogenic-positive feedback loop in which Aß induces Dkk1 expression, thereby activating non-canonical Wnt signalling to promote synapse loss and drive further Aß production. The Swedish familial AD variant of APP (APPSwe) more readily co-activates non-canonical, at the expense of canonical Wnt activity, indicating that its pathogenicity likely involves direct effects on synapses, in addition to increased Aß production. Finally, we report that pharmacological inhibition of the Aß-Dkk1-Aß positive feedback loop with the drug fasudil can restore the balance between Wnt pathways, prevent dendritic spine withdrawal in vitro, and reduce Aß load in vivo in mice with advanced amyloid pathology. These results clarify a relationship between Aß accumulation and synapse loss and provide direction for the development of potential disease-modifying treatments.

Deficiency in the transcription factor NRF2 worsens inflammatory parameters in a mouse model with combined tauopathy and amyloidopathy.

Chronic neuroinflammation is a hallmark of the onset and progression of brain proteinopathies such as Alzheimer disease (AD) and it is suspected to participate in the neurodegenerative process. Transcription factor NRF2, a master regulator of redox homeostasis, controls acute inflammation but its relevance in low-grade chronic inflammation of AD is inconclusive due to lack of good mouse models. We have addressed this question in a transgenic mouse that combines amyloidopathy and tauopathy with either wild type (AT-NRF2-WT) or NRF2-deficiency (AT-NRF2-KO). AT-NRF2-WT mice died prematurely, at around 14 months of age, due to motor deficits and a terminal spinal deformity but AT-NRF2-KO mice died roughly 2 months earlier. NRF2-deficiency correlated with exacerbated astrogliosis and microgliosis, as determined by an increase in GFAP, IBA1 and CD11b levels. The immunomodulatory molecule dimethyl fumarate (DMF), a drug already used for the treatment of multiple sclerosis whose main target is accepted to be NRF2, was tested in this preclinical model. Daily oral gavage of DMF during six weeks reduced glial and inflammatory markers and improved cognition and motor complications in the AT-NRF2-WT mice compared with the vehicle-treated animals. This study demonstrates the relevance of the inflammatory response in experimental AD, tightly regulated by NRF2 activity, and provides a new strategy to fight AD.

Transcription factor NFE2L2/NRF2 modulates chaperone-mediated autophagy through the regulation of LAMP2A.

Chaperone-mediated autophagy (CMA) is a selective degradative process for cytosolic proteins that contributes to the maintenance of proteostasis. The signaling mechanisms that control CMA are not fully understood but might involve response to stress conditions including oxidative stress. Considering the role of CMA in redoxtasis and proteostasis, we sought to determine if the transcription factor NFE2L2/NRF2 (nuclear factor, erythroid derived 2, like 2) has an impact on CMA modulation. In this work, we identified and validated 2 NFE2L2 binding sequences in the LAMP2 gene and demonstrated in several human and mouse cell types that NFE2L2 deficiency and overexpression was linked to reduced and increased LAMP2A levels, respectively. Accordingly, lysosomal LAMP2A levels were drastically reduced in nfe2l2-knockout hepatocytes, which also displayed a marked decrease in CMA activity. Oxidant challenge with paraquat or hydrogen peroxide, or pharmacological activation of NFE2L2 with sulforaphane or dimethyl fumarate also increased LAMP2A levels and CMA activity. Overall, our study identifies for the first time basal and inducible regulation of LAMP2A, and consequently CMA activity, by NFE2L2. ABBREVIATIONS: ACTB: actin, beta, ARE: antioxidant response element; ATG5: autophagy related 5; BACH1: BTB domain and CNC homolog 1; ChIP: chromatin immunoprecipitation; CMA: chaperone-mediated autophagy; DHE: dihydroethidium; DMF: dimethyl fumarate; ENCODE: Encyclopedia of DNA elements at the University of California, Santa Cruz; GAPDH: glyceraldehyde-3-phosphate dehydrogenase; GBA: glucosylceramidase beta; GFP: green fluorescent protein; HMOX1: heme oxygenase 1; H2O2: hydrogen peroxide; HSPA8/HSC70: heat shock protein family A (Hsp70) member 8; KEAP1: kelch like ECH associated protein 1; LAMP2A: lysosomal associated membrane protein 2A; LAMP2B: lysosomal associated membrane protein 2B; LAMP2C: lysosomal associated membrane protein 2C; LAMP1: lysosomal associated membrane protein 1; MAFF: MAF bZIP transcription factor F; MAFK: MAF bZIP transcription factor K; NFE2L2/NRF2: nuclear factor, erythroid derived 2, like 2; NQO1: NAD(P)H quinone dehydrogenase 1; PQ: paraquat; PI: protease inhibitors; qRT-PCR: quantitative real-time polymerase chain reaction; RNASE: ribonuclease A family member; SFN: sulforaphane; SQSTM1/p62: sequestosome 1; TBP: TATA-box binding protein.

Transcription Factor NRF2 as a Therapeutic Target for Chronic Diseases: A Systems Medicine Approach.

Systems medicine has a mechanism-based rather than a symptom- or organ-based approach to disease and identifies therapeutic targets in a nonhypothesis-driven manner. In this work, we apply this to transcription factor nuclear factor (erythroid-derived 2)-like 2 (NRF2) by cross-validating its position in a protein-protein interaction network (the NRF2 interactome) functionally linked to cytoprotection in low-grade stress, chronic inflammation, metabolic alterations, and reactive oxygen species formation. Multiscale network analysis of these molecular profiles suggests alterations of NRF2 expression and activity as a common mechanism in a subnetwork of diseases (the NRF2 diseasome). This network joins apparently heterogeneous phenotypes such as autoimmune, respiratory, digestive, cardiovascular, metabolic, and neurodegenerative diseases, along with cancer. Importantly, this approach matches and confirms in silico several applications for NRF2-modulating drugs validated in vivo at different phases of clinical development. Pharmacologically, their profile is as diverse as electrophilic dimethyl fumarate, synthetic triterpenoids like bardoxolone methyl and sulforaphane, protein-protein or DNA-protein interaction inhibitors, and even registered drugs such as metformin and statins, which activate NRF2 and may be repurposed for indications within the NRF2 cluster of disease phenotypes. Thus, NRF2 represents one of the first targets fully embraced by classic and systems medicine approaches to facilitate both drug development and drug repurposing by focusing on a set of disease phenotypes that appear to be mechanistically linked. The resulting NRF2 drugome may therefore rapidly advance several surprising clinical options for this subset of chronic diseases.

Amyloid ß synaptotoxicity is Wnt-PCP dependent and blocked by fasudil.

INTRODUCTION: Synapse loss is the structural correlate of the cognitive decline indicative of dementia. In the brains of Alzheimer's disease sufferers, amyloid ß (Aß) peptides aggregate to form senile plaques but as soluble peptides are toxic to synapses. We previously demonstrated that Aß induces Dickkopf-1 (Dkk1), which in turn activates the Wnt-planar cell polarity (Wnt-PCP) pathway to drive tau pathology and neuronal death. METHODS: We compared the effects of Aß and of Dkk1 on synapse morphology and memory impairment while inhibiting or silencing key elements of the Wnt-PCP pathway. RESULTS: We demonstrate that Aß synaptotoxicity is also Dkk1 and Wnt-PCP dependent, mediated by the arm of Wnt-PCP regulating actin cytoskeletal dynamics via Daam1, RhoA and ROCK, and can be blocked by the drug fasudil. DISCUSSION: Our data add to the importance of aberrant Wnt signaling in Alzheimer's disease neuropathology and indicate that fasudil could be repurposed as a treatment for the disease.

Transcription factor NRF2 controls the fate of neural stem cells in the subgranular zone of the hippocampus.

Neural stem/progenitor cells (NSPCs) located at the subgranular zone (SGZ) of the hippocampus participate in the maintenance of synaptic networks that ensure cognitive functions during life. Although it is known that this neurogenic niche losses activity with oxidative stress and ageing, the molecular events involved in its regulation are largely unknown. Here, we studied the role of transcription factor Nuclear Factor-Erythroid 2-Related Factor 2 (NRF2) in the control of NSPCs destinies in the SGZ. We first describe that NRF2-knockout (Nrf2-/-) mice exhibit impaired long term potentiation, a function that requires integrity of the SGZ, therefore suggesting a cognitive deficit that might be linked to hippocampal neurogenesis. Then, we found a reduction in NSCs from birth to adulthood that was exacerbated in Nrf2-/- vs. Nrf2+/+ mice. The clonogenic and proliferative capacity of SGZ-derived NSPCs from newborn and 3-month-old Nrf2-/- mice was severely reduced as determined in neurosphere cultures. Nrf2-deficiency also impaired neuronal differentiation both the SGZ, and in neurosphere differentiation assays, leading to an abnormal production of astrocytes and oligodendrocytes vs. neurons. Rescue of Nrf2-/- NSPCs by ectopic expression of NRF2 attenuated the alterations in clonogenic, proliferative and differentiating capacity of hippocampal NSPCs. In turn, knockdown of the NRF2 gene in wild type NSPCs reproduced the data obtained with Nrf2-/- NSPCs. Our findings demonstrate the importance of NRF2 in the maintenance of proper proliferation and differentiation rates of hippocampal NSPCs and suggest that interventions to up-regulate NRF2 might provide a mechanism to preserve the neurogenic functionality of the hippocampus.

NRF2 deficiency replicates transcriptomic changes in Alzheimer's patients and worsens APP and TAU pathology.

Failure to translate successful neuroprotective preclinical data to a clinical setting in Alzheimer's disease (AD) indicates that amyloidopathy and tauopathy alone provide an incomplete view of disease. We have tested here the relevance of additional homeostatic deviations that result from loss of activity of transcription factor NRF2, a crucial regulator of multiple stress responses whose activity declines with ageing. A transcriptomic analysis demonstrated that NRF2-KO mouse brains reproduce 7 and 10 of the most dysregulated pathways of human ageing and AD brains, respectively. Then, we generated a mouse that combines amyloidopathy and tauopathy with either wild type (AT-NRF2-WT) or NRF2-deficiency (AT-NRF2-KO). AT-NRF2-KO brains presented increased markers of oxidative stress and neuroinflammation as well as higher levels of insoluble phosphorylated-TAU and Aß*56 compared to AT-NRF2-WT mice. Young adult AT-NRF2-KO mice exhibited deficits in spatial learning and memory and reduced long term potentiation in the perforant pathway. This study demonstrates the relevance of normal homeostatic responses that decline with ageing, such as NRF2 activity, in the protection against proteotoxic, inflammatory and oxidative stress and provide a new strategy to fight AD.

Discovery of the first dual GSK3ß inhibitor/Nrf2 inducer. A new multitarget therapeutic strategy for Alzheimer's disease.

The formation of neurofibrillary tangles (NFTs), oxidative stress and neuroinflammation have emerged as key targets for the treatment of Alzheimer's disease (AD), the most prevalent neurodegenerative disorder. These pathological hallmarks are closely related to the over-activity of the enzyme GSK3ß and the downregulation of the defense pathway Nrf2-EpRE observed in AD patients. Herein, we report the synthesis and pharmacological evaluation of a new family of multitarget 2,4-dihydropyrano[2,3-c]pyrazoles as dual GSK3ß inhibitors and Nrf2 inducers. These compounds are able to inhibit GSK3ß and induce the Nrf2 phase II antioxidant and anti-inflammatory pathway at micromolar concentrations, showing interesting structure-activity relationships. The association of both activities has resulted in a remarkable anti-inflammatory ability with an interesting neuroprotective profile on in vitro models of neuronal death induced by oxidative stress and energy depletion and AD. Furthermore, none of the compounds exhibited in vitro neurotoxicity or hepatotoxicity and hence they had improved safety profiles compared to the known electrophilic Nrf2 inducers. In conclusion, the combination of both activities in this family of multitarget compounds confers them a notable interest for the development of lead compounds for the treatment of AD.

Modulation of proteostasis by transcription factor NRF2 and impact in neurodegenerative diseases.

Neurodegenerative diseases are linked to the accumulation of specific protein aggregates, suggesting an intimate connection between injured brain and loss of proteostasis. Proteostasis refers to all the processes by which cells control the abundance and folding of the proteome thanks to a wide network that integrates the regulation of signaling pathways, gene expression and protein degradation systems. This review attempts to summarize the most relevant findings about the transcriptional modulation of proteostasis exerted by the transcription factor NRF2 (nuclear factor (erythroid-derived 2)-like 2). NRF2 has been classically considered as the master regulator of the antioxidant cell response, although it is currently emerging as a key component of the transduction machinery to maintain proteostasis. As we will discuss, NRF2 could be envisioned as a hub that compiles emergency signals derived from misfolded protein accumulation in order to build a coordinated and perdurable transcriptional response. This is achieved by functions of NRF2 related to the control of genes involved in the maintenance of the endoplasmic reticulum physiology, the proteasome and autophagy.