Pyridoxine (VB6) restores the down‐regulation of serine palmitoyltransferase mRNA expression in keratinocytes cultured in highly oxidative conditions through enhancement of the intracellular antioxidant system. (30th January 2019)

• Record Type: Journal Article
• Authors: Mizutani, Taeko; Yamawaki, Yumiko; Okano, Yuri; Masaki, Hitoshi
• Is Part Of: Experimental dermatology. Volume 28(2019)Supplement 1
• Page Start: 43
• Page End: 49
• Publication Date: 2019-01-30
• Subjects: carbonylated proteins -- keratinocytes -- nuclear factor E2‐related factor 2 (Nrf2) -- pyridoxine (VB6) -- serine palmitoyltransferase; Dermatology -- Periodicals; 616.5
• DOI: 10.1111/exd.13822
• Languages: English
• ISSNs: 0906-6705

Abstract

Abstract: Background: Pyridoxine (VB6 ), which acts as a coenzyme in the biosynthesis of niacin, is formulated in pharmaceuticals to treat skin roughness. However, the mechanism of action of VB6 is not known precisely. Objective: This study was conducted to clarify the influence of highly oxidative conditions on the expression of skin moisture‐related mRNAs and to evaluate the preventive effects of VB6 focusing on antioxidant behaviour. Methods: Intracellular levels of reactive oxygen species (ROS) in normal human epidermal keratinocytes (NHEKs) were determined using the 2′, 7′‐dichlorofluorescein diacetate assay. Real‐time PCR was employed to investigate the influence of higher oxidative conditions on the expression of mRNAs encoding serine palmitoyl transferase (SPT) and filaggrin, and to characterize the mechanism of the antioxidant effect of VB6 . Intracellular glutathione was quantified using an assay based on the glutathione recycling system with 5, 5′‐dithiobis (2‐nitrobenzoic acid) reagent and glutathione reductase. Carbonylated proteins (CPs) were semi‐quantified by detecting aldehyde residues. Results: Treatment of NHEKs with BSO increased the level of intracellular CPs by interfering with intracellular glutathione synthesis. Further, treatment with BSO down‐regulated the expression level of SPT mRNA, but VB6 restored SPT mRNA expression in BSO‐treated NHEKs. VB6 decreased the level of intracellular CPs with or without BSO treatment in a dose‐dependent manner. In addition, VB6 increased levels of intracellular NADH/NADPH and glutathione through the activation of nuclear factor E2‐related factor 2 (Nrf2) signalling. Conclusion: These results suggest that highly oxidative conditions cause an impaired skin barrier function due to the down‐regulation of SPT that results in skin roughness. VB6 improved the down‐regulation of SPT mRNA expression initiated by highly oxidative conditions by enhancing the intracellular antioxidant system.