Ascorbic acid alters cell fate commitment of human neural progenitors in a WNT/β-catenin/ROS signaling dependent manner

Abstract

BackgroundImproving the neuronal yield from in vitro cultivated neural progenitor cells (NPCs) is an essential challenge in transplantation therapy in neurological disorders. In this regard, Ascorbic acid (AA) is widely used to expand neurogenesis from NPCs in cultures although the mechanisms of its action remain unclear. Neurogenesis from NPCs is regulated by the redox-sensitive WNT/β-catenin signaling pathway. We therefore aimed to investigate how AA interacts with this pathway and potentiates neurogenesis.MethodsEffects of 200 μM AA were compared with the pro-neurogenic reagent and WNT/β-catenin signaling agonist lithium chloride (LiCl), and molecules with antioxidant activities i.e. N-acetyl-L-cysteine (NAC) and ruthenium red (RuR), in differentiating neural progenitor ReNcell VM cells. Cells were supplemented with reagents for two periods of treatment: a full period encompassing the whole differentiation process versus an early short period that is restricted to the cell fate commitment stage. Intracellular redox balance and reactive oxygen species (ROS) metabolism were examined by flow cytometry using redox and ROS sensors. Confocal microscopy was performed to assess cell viability, neuronal yield, and levels of two proteins: Nucleoredoxin (NXN) and the WNT/β-catenin signaling component Dishevelled 2 (DVL2). TUBB3 and MYC gene responses were evaluated by quantitative real-time PCR. DVL2-NXN complex dissociation was measured by fluorescence resonance energy transfer (FRET).ResultsIn contrast to NAC which predictably exhibited an antioxidant effect, AA treatment enhanced ROS metabolism with no cytotoxic induction. Both drugs altered ROS levels only at the early stage of the differentiation as no changes were held beyond the neuronal fate commitment stage. FRET studies showed that AA treatment accelerated the redox-dependent release of the initial pool of DVL2 from its sequestration by NXN, while RuR treatment hampered the dissociation of the two proteins. Accordingly, AA increased WNT/β-catenin signaling output i.e. MYC mRNA level, whereas RuR attenuated it. Moreover, AA improved neurogenesis as much as LiCl as both TUBB3-positive cell yield and TUBB3 mRNA level increased, while NAC or RuR attenuated neurogenesis. Markedly, the neurogenesis outputs between the short and the full treatment with either NAC or AA were found unchanged, supporting our model that neuronal yield is altered by events taking place at the early phase of differentiation.ConclusionsOur findings demonstrate that AA treatment elevates ROS metabolism in a non-lethal manner prior to the NPCs commitment to their neuronal fate. Such effect stimulates the redox-sensitive DVL2 activation and WNT/β-catenin signaling response that would enhance the ensuing neuronal cell differentiation.Electronic supplementary materialThe online version of this article (10.1186/s12929-017-0385-1) contains supplementary material, which is available to authorized users.

Induction of Neuroinflammation and Neurotoxicity by Synthetic Hemozoin

“…In this study, we showed for the first time that hemozoin-induced damage to differentiated human neural progenitor cells is accompanied by marked induction of oxidative stress. These results are consistent with previous reports showing that oxidative stress mediates toxicity to human neural progenitor cells (Rharass et al 2017; Chang et al 2013). Remarkably, our experiments showed hemozoin induced caspase-6 activation in differentiated ReNcell VM human neural progenitor cells.…”

Supporting Cell-Based Tendon Therapy: Effect of PDGF-BB and Ascorbic Acid on Rabbit Achilles Tenocytes In Vitro

“…Hence, although not elucidated in detail up to date, AA may influence tenascin-C gene expression by other regulatory pathways than PDGF-BB does; and JAK/STAT pathway may play a role. In addition, AA has been reported to act via Wnt signaling [81,82], but the regulation of tenascin-C expression by the Wnt/β-catenin signaling pathway has not been reported for tenocytes yet, but only for macrophages [83] or smooth muscle cells [84].…”

Niacin in the Central Nervous System: An Update of Biological Aspects and Clinical Applications

“…Like other vitamins (ascorbic acid, calcitriol and retinoic acid) [ 118 , 119 , 120 , 121 , 122 ], nicotinamide affects neurogenesis by accelerating differentiation of embryonic stem cells or neural progenitors into post-mitotic neurons [ 123 , 124 ]. In vitro vitamin supplementation promotes progression of undifferentiated stem cells to neural progenitors, which further mature into efficient GABAergic neurons; the pro-inducing action is time-dependent as the effects are more pronounced when the vitamin is early received early (day 0) [ 124 ].…”