The putative interplay between DJ-1/NRF2 and Dimethyl Fumarate: A potentially important pharmacological target

Riboflavin protects against heart failure via SCAD-dependent DJ-1-Keap1-Nrf2 signalling pathway

BACKGROUND AND PURPOSE

Our recent studies have shown that flavin adenine dinucleotide (FAD) exerts cardiovascular protective effects by supplementing short-chain acyl-CoA dehydrogenase (SCAD). The current study aimed to elucidate whether riboflavin (the precursor of FAD) could improve heart failure via activating SCAD and the DJ-1-Keap1-Nrf2 signalling pathway.

EXPERIMENTAL APPROACH

Riboflavin treatment was given to the mouse transverse aortic constriction (TAC)-induced heart failure model. Cardiac structure and function, energy metabolism and apoptosis index were assessed, and relevant signalling proteins were analysed. The mechanisms underlying the cardioprotection by riboflavin were analysed in the cell apoptosis model induced by tert-butyl hydroperoxide (tBHP).

KEY RESULTS

In vivo, riboflavin ameliorated myocardial fibrosis and energy metabolism, improved cardiac dysfunction and inhibited oxidative stress and cardiomyocyte apoptosis in TAC-induced heart failure. In vitro, riboflavin ameliorated cell apoptosis in H9C2 cardiomyocytes by decreasing reactive oxygen species (ROS). At the molecular level, riboflavin significantly restored FAD content, SCAD expression and enzymatic activity, activated DJ-1 and inhibited the Keap1-Nrf2/HO1 signalling pathway in vivo and in vitro. SCAD knockdown exaggerated the tBHP-induced DJ-1 decrease and Keap1-Nrf2/HO1 signalling pathway activation in H9C2 cardiomyocytes. The knockdown of SCAD abolished the anti-apoptotic effects of riboflavin on H9C2 cardiomyocytes. DJ-1 knockdown hindered SCAD overexpression anti-apoptotic effects and regulation on Keap1-Nrf2/HO1 signalling pathway in H9C2 cardiomyocytes.

CONCLUSIONS AND IMPLICATIONS

Riboflavin exerts cardioprotective effects on heart failure by improving oxidative stress and cardiomyocyte apoptosis via FAD to stimulate SCAD and then activates the DJ-1-Keap1-Nrf2 signalling pathway.

Research Progress on Targeted Antioxidant Therapy and Vitiligo

Vitiligo is a common acquired depigmenting disease characterized by the loss of functional melanocytes and epidermal melanin. Vitiligo has a long treatment cycle and slow results, which is one of the most difficult challenges for skin diseases. Oxidative stress plays an important role as an initiating and driving factor in the pathogenesis of vitiligo. Antioxidant therapy has recently become a research hotspot in vitiligo treatment. A series of antioxidants has been discovered and applied to the treatment of vitiligo, which has returned satisfactory results. This article briefly reviews the relationship between oxidative stress and vitiligo. We also describe the progress of targeted antioxidant therapy in vitiligo, with the aim of providing a reference for new drug development and treatment options for this condition.

Recent Advances in Understanding Nrf2 Agonism and Its Potential Clinical Application to Metabolic and Inflammatory Diseases

Oxidative stress is a major component of cell damage and cell fat, and as such, it occupies a central position in the pathogenesis of metabolic disease. Nuclear factor-erythroid-derived 2-related factor 2 (Nrf2), a key transcription factor that coordinates expression of genes encoding antioxidant and detoxifying enzymes, is regulated primarily by Kelch-like ECH-associated protein 1 (Keap1). However, involvement of the Keap1–Nrf2 pathway in tissue and organism homeostasis goes far beyond protection from cellular stress. In this review, we focus on evidence for Nrf2 pathway dysfunction during development of several metabolic/inflammatory disorders, including diabetes and diabetic complications, obesity, inflammatory bowel disease, and autoimmune diseases. We also review the beneficial role of current molecular Nrf2 agonists and summarize their use in ongoing clinical trials. We conclude that Nrf2 is a promising target for regulation of numerous diseases associated with oxidative stress and inflammation. However, more studies are needed to explore the role of Nrf2 in the pathogenesis of metabolic/inflammatory diseases and to review safety implications before therapeutic use in clinical practice.

Critical Involvement of Glial Cells in Manganese Neurotoxicity

Over the years, most of the research concerning manganese exposure was restricted to the toxicity of neuronal cells. Manganese is an essential trace element that in high doses exerts neurotoxic effects. However, in the last two decades, efforts have shifted toward a more comprehensive approach that takes into account the involvement of glial cells in the development of neurotoxicity as a brain insult. Glial cells provide structural, trophic, and metabolic support to neurons. Nevertheless, these cells play an active role in adult neurogenesis, regulation of synaptogenesis, and synaptic plasticity. Disturbances in glial cell function can lead to neurological disorders, including neurodegenerative diseases. This review highlights the pivotal role that glial cells have in manganese-induced neurotoxicity as well as the most sounding mechanisms involved in the development of this phenomenon.

Ischemic Postconditioning-Mediated DJ-1 Activation Mitigate Intestinal Mucosa Injury Induced by Myocardial Ischemia Reperfusion in Rats Through Keap1/Nrf2 Pathway

Intestinal mucosal barrier dysfunction induced by myocardial ischemia reperfusion (IR) injury often leads to adverse cardiovascular outcomes after myocardial infarction. Early detection and prevention of remote intestinal injury following myocardial IR may help to estimate and improve prognosis after acute myocardial infarction (AMI). This study investigated the protective effect of myocardial ischemic postconditioning (IPo) on intestinal barrier injury induced by myocardial IR and the underlying cellular signaling mechanisms with a focus on the DJ-1. Adult SD rats were subjected to unilateral myocardial IR with or without ischemic postconditioning. After 30 min of ischemia and 120 min of reperfusion, heart tissue, intestine, and blood were collected for subsequent examination. The outcome measures were (i) intestinal histopathology, (ii) intestinal barrier function and inflammatory responses, (iii) apoptosis and oxidative stress, and (iv) cellular signaling changes. IPo significantly attenuated intestinal injury induced by myocardial IR. Furthermore, IPo significantly increased DJ-1, nuclear Nrf2, NQO1, and HO-1 expression in the intestine and inhibited IR-induced apoptosis and oxidative stress. The protective effect of IPo was abolished by the knockdown of DJ-1. Conversely, the overexpression of DJ-1 provided a protective effect similar to that of IPo. Our data indicate that IPo protects the intestine against myocardial IR, which is likely mediated by the upregulation of DJ-1/Nrf2 pathway.

Vitexin protects melanocytes from oxidative stress via activating MAPK-Nrf2/ARE pathway

INTRODUCTION

Vitiligo is the most common type of depigmented skin disease. Cellular oxidative stress caused by reactive oxygen species (ROS) has been implicated in the pathogenesis of vitiligo. Nuclear factor E2-related factor 2 (Nrf2)/antioxidant response element (ARE) pathway plays an important role in melanocytes against hydrogen peroxide (H₂O₂) induced oxidative stress. In addition, vitexin may protect vitiligo by inhibiting oxidative stress and inflammation.

OBJECTIVE

In the present study, we aimed to investigate the antioxidant effect of vitexin-activated mitogen-activated protein kinase (MAPK)-Nrf2/ARE axis in vitiligo.

METHODS

MTT assay identified cell viability of human melanocyte PIG1. Cell apoptosis was evaluated by flow cytometry. Gene and protein expression levels were analyzed by quantitative real-time PCR (qPCR) and Western blotting. Enzyme-linked immunosorbent assay (ELISA) was used to detect the expressions of inflammatory factors and ROS production.

RESULTS

Vitexin inhibited H₂O₂-induced melanocyte apoptosis and promoted cell proliferation. Moreover, vitexin decreased expression of interleukin-1β (IL-1β), IL-17A, and ROS in melanocytes induced by H₂O₂. Subsequently, activation of MAPK-Nrf2/ARE signaling was readily induced by vitexin treatment, as evidenced by the upregulation of antioxidant genes including heme oxygenase 1 (HO-1) and superoxide dismutase (SOD). Knockdown of Nrf2 reversed the protective effect of vitexin on H₂O₂-induced melanocytes. And, knockdown of Nrf2 increased the expression of IL-1β, IL-17A and ROS, and reduced HO-1 and SOD expression.

CONCLUSIONS

Vitexin protected melanocytes from oxidative stress by activating MAPK-Nrf2/ARE signaling pathway. Our results suggested that the role of the Nrf2/ARE axis in the antioxidant defense of melanocytes, and the potential therapeutic strategy for vitiligo.

AITC induces MRP1 expression by protecting against CS/CSE-mediated DJ-1 protein degradation via activation of the DJ-1/Nrf2 axis

The present study aimed to examine the effect of allyl isothiocyanate (AITC) on chronic obstructive pulmonary disease and to investigate whether upregulation of multidrug resistance-associated protein 1 (MRP1) associated with the activation of the PARK7 (DJ-1)/nuclear factor erythroid 2-related factor 2 (Nrf2) axis. Lung function indexes and histopathological changes in mice were assessed by lung function detection and H&E staining. The expression levels of Nrf2, MRP1, heme oxygenase-1 (HO-1), and DJ-1 were determined by immunohistochemistry, Western blotting and reverse transcription-quantitative polymerase chain reaction. Next, the expression of DJ-1 in human bronchial epithelial (16HBE) cells was silenced by siRNA, and the effect of DJ-1 expression level on cigarette smoke extract (CSE)-stimulated protein degradation and AITC-induced protein expression was examined. The expression of DJ-1, Nrf2, HO-1, and MRP1 was significantly decreased in the wild type model group, while the expression of each protein was significantly increased after administration of AITC. Silencing the expression of DJ-1 in 16HBE cells accelerated CSE-induced protein degradation, and significantly attenuated the AITC-induced mRNA and protein expression of Nrf2 and MRP1. The present study describes a novel mechanism by which AITC induces MRP1 expression by protecting against CS/CSEmediated DJ-1 protein degradation via activation of the DJ-1/Nrf2 axis.

Nrf2 Activation by SK-119 Attenuates Oxidative Stress, UVB, and LPS-Induced Damage

BACKGROUND/AIMS

The Nrf2 signaling pathway plays a pivotal role in neutralizing excess reactive oxygen species formation and therefore enhancing the endogenous cellular protection mechanism. Thus, activating this pathway may provide therapeutic options against oxidative stress-related disorders. We have recently applied a computer-aided drug design approach to the design and synthesis of novel Nrf2 enhancers. The current study was aimed at investigating the potential beneficial impact of (E)-5-oxo-1-(4-((2,4,6-trihydroxybenzylidene)amino)phenyl)pyrrolidine-3-carboxylic acid (SK-119) in skin oxidative damage models.

METHODS

SK-119, tested initially in PC-12 cells, attenuated oxidative stress-induced cytotoxicity concomitantly with Nrf2 activation. The potential impact of this compound was evaluated in skin-based disease models both in vitro (HaCaT cells) and ex vivo (human skin organ culture).

RESULTS

The data clearly showed the marked anti-inflammatory and photoprotection properties of the compound; SK-119-treated cells or tissues displayed a reduction in cytokine secretion induced by lipopolysaccharides (LPS) in a manner comparable with dexamethasone. In addition, topical application of SK-119 was able to block UVB-induced oxidative stress and attenuated caspase-mediated apoptosis, DNA adduct formation, and the concomitant cellular damage.

CONCLUSION

These results indicate that SK-119 is an Nrf2 activator that can be used as a prototype molecule for the development of novel treatments of dermatological disorders related to oxidative stress.