Modulation of keratinocyte expression of antioxidants by 4-hydroxynonenal, a lipid peroxidation end product

Abstract

4-Hydroxynonenal (4-HNE) is a lipid peroxidation end product generated in response to oxidative stress in the skin. Keratinocytes contain an array of antioxidant enzymes which protect against oxidative stress. In these studies, we characterized 4-HNE-induced changes in antioxidant expression in mouse keratinocytes. Treatment of primary mouse keratinocytes and PAM 212 keratinocytes with 4-HNE increased mRNA expression for heme oxygenase-1 (HO-1), catalase, NADPH:quinone oxidoreductase (NQO1) and glutathione S-transferase (GST) A1-2, GSTA3 and GSTA4. In both cell types, HO-1 was the most sensitive, increasing 86-98 fold within 6 h. Further characterization of the effects of 4-HNE on HO-1 demonstrated concentration- and time-dependent increases in mRNA and protein expression which were maximum after 6 h with 30 μM. 4-HNE stimulated keratinocyte Erk1/2, JNK and p38 MAP kinases, as well as PI3 kinase. Inhibition of these enzymes suppressed 4-HNE-induced HO-1 mRNA and protein expression. 4-HNE also activated Nrf2 by inducing its translocation to the nucleus. 4-HNE was markedly less effective in inducing HO-1 mRNA and protein in keratinocytes from Nrf2−/− mice, when compared to wild type mice, indicating that Nrf2 also regulates 4-HNE-induced signaling. Western blot analysis of caveolar membrane fractions isolated by sucrose density centrifugation demonstrated that 4-HNE-induced HO-1 is localized in keratinocyte caveolae. Treatment of the cells with methyl-β-cyclodextrin, which disrupts caveolar structure, suppressed 4-HNE-induced HO-1. These findings indicate that 4-HNE modulates expression of antioxidant enzymes in keratinocytes, and that this can occur by different mechanisms. Changes in expression of keratinocyte antioxidants may be important in protecting the skin from oxidative stress.

JNK1 ablation in mice confers long‐term metabolic protection from diet‐induced obesity at the cost of moderate skin oxidative damage

“…Therefore, our data do not exclude a non–cell‐autonomous action of JNK1 in promoting oxidative stress tolerance. Nonetheless, a role for JNK in the control of antioxidant gene expression in cultured skin cells has been reported (34, 35, 40, 41), and that theskinwas theonlytissueofJNK1 –/– mice displaying increased oxidative damage is consistent with the idea that JNK1 activity within a specific skin cell type may protect against local oxidative damage. Indeed, because JNK1 deletion improves metabolic homeostasis and reduces adiposity, the expected systemic outcome of JNK1 deletion would be reduced oxidative stress, as observed in liver and adipose tissue.…”

“…By contrast, MDA levels were significantly elevated in skin samples from JNK1 –/– mice compared to WT controls indicating increased oxidative damage in this tissue. To further learn about the mechanisms of increased oxidative damage in the skin of JNK1 –/– mice, we measured mRNA levels of HO‐1, a potent antioxidant and anti‐inflammatory enzyme with expression that has been shown to be elevated in keratinocyte cell cultures by oxidative stress inducers and by lipid peroxidation products in a JNK1‐dependent manner (34, 35). HO‐1 mRNA levels were similar between genotypes in kidney, heart, and liver, but were markedly reduced in white adipose tissue of JNK1 –/– mice compared to WT controls (Fig.…”

Rutin as a Mediator of Lipid Metabolism and Cellular Signaling Pathways Interactions in Fibroblasts Altered by UVA and UVB Radiation

“…However, enhanced Nrf2 phosphorylation may also be associated with the increased anandamide or 2-AG levels observed in this study, while significant downregulation of cannabinoid receptor levels after rutin treatment of UV-irradiated fibroblasts may result in decreased signal transduction via the downregulation of protein phosphorylation. Nrf2 expression in rutin-treated, UV-irradiated fibroblasts was downregulated and positively correlated with expression of another transcription factor, NF κ B, the activation of which is also dependent on the actions of ROS and reactive aldehydes generated during lipid peroxidation [ 80 ].…”

Lipid peroxidation biomarkers in adolescents with or at high-risk for bipolar disorder

“…Such factors include Nrf2, AP-1, PPAR and NF-κB, which have a great impact on gene transcription (Forman et al, 2003; Kim and Yang, 2013; Lim et al, 2006; Miller et al, 2013). Moreover, this molecule could have an important role in the pathophysiology of BD since it could also stimulate protein modification and activation of Erk1/2, JNK and p38 MAP kinases, as well as phosphoinositide-3-kinase (PI3)/Akt (Lin et al, 2014; Zheng et al, 2014). All of these alterations have been observed in adults with BD (Andreazza et al, 2013; Kerner et al, 2013).…”