NRF2 Activation Restores Disease Related Metabolic Deficiencies in Olfactory Neurosphere-Derived Cells from Patients with Sporadic Parkinson's Disease

Abstract

BackgroundWithout appropriate cellular models the etiology of idiopathic Parkinson's disease remains unknown. We recently reported a novel patient-derived cellular model generated from biopsies of the olfactory mucosa (termed olfactory neurosphere-derived (hONS) cells) which express functional and genetic differences in a disease-specific manner. Transcriptomic analysis of Patient and Control hONS cells identified the NRF2 transcription factor signalling pathway as the most differentially expressed in Parkinson's disease.ResultsWe tested the robustness of our initial findings by including additional cell lines and confirmed that hONS cells from Patients had 20% reductions in reduced glutathione levels and MTS [3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)-2H-tetrazolium, inner salt] metabolism compared to cultures from healthy Control donors. We also confirmed that Patient hONS cells are in a state of oxidative stress due to higher production of H2O2 than Control cultures. siRNA-mediated ablation of NRF2 in Control donor cells decreased both total glutathione content and MTS metabolism to levels detected in cells from Parkinson's Disease patients. Conversely, and more importantly, we showed that activation of the NRF2 pathway in Parkinson's disease hONS cultures restored glutathione levels and MTS metabolism to Control levels. Paradoxically, transcriptomic analysis after NRF2 pathway activation revealed an increased number of differentially expressed mRNAs within the NRF2 pathway in L-SUL treated Patient-derived hONS cells compared to L-SUL treated Controls, even though their metabolism was restored to normal. We also identified differential expression of the PI3K/AKT signalling pathway, but only post-treatment.ConclusionsOur results confirmed NRF2 as a potential therapeutic target for Parkinson's disease and provided the first demonstration that NRF2 function was inducible in Patient-derived cells from donors with uniquely varied genetic backgrounds. However, our results also demonstrated that the response of PD patient-derived cells was not co-ordinated in the same way as in Control cells. This may be an important factor when developing new therapeutics.

The multifaceted role of Nrf2 in mitochondrial function

“…Second, Nrf2 function has been reported to be impaired in mitochondria-related disorders, whereas Nrf2 activation has beneficial effects. For example, the Nrf2 pathway is suppressed in Parkinson's disease patient derived olfactory neurosphere cells [44], and Nrf2 activation restores the glutathione levels in these cells [45]. This Nrf2 suppression is especially prominent in Friedrich's ataxia where Nrf2 activation upon oxidative stress was found to be blocked in patient fibroblasts [46].…”

Sulforaphane Decreases Endothelial Cell Apoptosis in Fuchs Endothelial Corneal Dystrophy: A Novel Treatment

“…Sulforaphane (1-isothiocyanato-[4R]-[methylsulfinyl]-butane; SFN) is one of the best-studied Nrf2 level enhancers, whose cytoprotective effects have been widely described as potential treatment for multiple chronic oxidative stressrelated conditions. 9,13 SFN is a naturally occurring glucosinolate 14 found in green cruciferous vegetables such as broccoli. 14 SFN has been shown to cause post-transplantation modification of Keap1/Nrf2 proteins by modifying sulfhydryl residues of Keap1, causing the release and activation of Nrf2, 15 and/or by induction of ERK and JNK-mediated phosphorylation and activation of Nrf2.…”

Role of the Transcription Factor Nrf2 in Parkinson’s Disease: New Insights

“…Related to PD, patient-derived cellular model generated from biopsies of the olfactory mucosa (termed olfactory neurosphere-derived (hONS) cells) had a 20% reduction in reduced glutathione levels and MTS [3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)-2H-tetrazolium, inner salt] metabolism compared to cultures from healthy control donors. But more importantly, activation of the NRF2 pathway with SFN in PD hONS cultures restored glutathione and MTS metabolism to control levels [93]. In wild-type mice, but not in Nrf2-knockout mice, SFN protected against MPTPinduced death of nigral dopaminergic neurons.…”