Nrf2 in keratinocytes modulates UVB-induced DNA damage and apoptosis in melanocytes through MAPK signaling

Abstract

Responses of melanocytes (MC) to ultraviolet (UV) irradiation can be influenced by their neighbouring keratinocytes (KC). We investigated the role of Nrf2 in regulating paracrine effects of KC on UVB-induced MC responses through phosphorylation of MAPKs in association with oxidative stress in primary human MC cocultured with primary human KC using a transwell co-culture system and small-interfering RNA-mediated silencing of Nrf2 (siNrf2). The mechanisms by which Nrf2 modulated paracrine factors including α-melanocyte-stimulating hormone (α-MSH) and paracrine effects of KC on UVB-mediated apoptosis were also assessed. Our findings showed that co-culture of MC with siNrf2-transfected KC enhanced UVB-mediated cyclobutane pyrimidine dimer (CPD) formation, apoptosis and oxidant formation, together with phosphorylation of ERK, JNK and p38 in MC. Treatment of MC with conditioned medium (CM) from Nrf2-depleted KC also increased UVB-mediated MC damage, suggesting that KC modulated UVB-mediated MC responses via paracrine effects. Additionally, depletion of Nrf2 in KC suppressed UVB-induced α-MSH levels as early as 30 min post-irradiation, although pretreatment with N-acetylcysteine (NAC) elevated its levels in CM from siNrf2-transfected KC. Furthermore, NAC reversed the effect of CM from Nrf2-depleted KC on UVB-induced apoptosis and inflammatory response in MC. Our study demonstrates for the first time that KC provided a rescue effect on UVB-mediated MC damage, although depletion of Nrf2 in KC reversed its protective effects on MC in a paracrine fashion in association with elevation of ROS levels and activation of MAPK pathways in MC. Nrf2 may indirectly regulate the paracrine effects of KC probably by affecting levels of the paracrine factor α-MSH via a ROS-dependent mechanism.

Nrf2‐lncRNA controls cell fate by modulating p53‐dependent Nrf2 activation as an miRNA sponge for Plk2 and p21 cip1

“…As an adaptive response to cell survival and maintenance of redox homeostasis, Nrf2 is tightly and precisely controlled (51). Despite numerous studies highlighting the need for Nrf2 for cell survival against stress accompanying p53 activation (e.g., DNA damage) (52)(53)(54), the pathways and associated molecules engaged in the event remain unknown. The results from this study support the evidence that both Plk2 and p21 cip1 have the ability to activate Nrf2 as a downstream target of Nrf2-lncRNA.…”

Rapamycin Protects Skin Fibroblasts from Ultraviolet B-Induced Photoaging by Suppressing the Production of Reactive Oxygen Species

“…UVB-exposed MDFs pretreated with RAPA showed a significant decrease in staining intensity and the percentage of SA-β-gal-positive cells and rescue of the elongated cell shape. UVB irradiation-mediated CPD formation can lead to apoptotic cell death in dermal cells, with the severity of DNA damage serving as a crucial molecular trigger [32, 33]. Our previous experiments showed that UVB caused S-phase cell cycle arrest to prevent further DNA damage and minimize the likelihood of introducing gene mutations in daughter cells.…”

Melatonin and its derivatives counteract the ultraviolet B radiation‐induced damage in human and porcine skin ex vivo

“…Nuclear and cytoplasmic fractions of total proteins were isolated separately using a Nuclear Extract Kit according to the manufacturer’s instructions (Active Motif, Carlsbad, CA, USA). Western blot analyses were performed to detect phosphorylated p53, Nrf2, catalase (CAT), CuSOD (superoxide dismutase), and MnSOD protein expression as previously described . The proteins were resolved on the 8%‐16% (w/v) SDS‐PAGE gel and transferred to the PVDF membrane.…”

“…Western blot analyses were performed to detect phosphorylated p53, Nrf2, catalase (CAT), CuSOD (superoxide dismutase), and MnSOD protein expression as previously described. 48 The proteins were resolved on the 8%-16% (w/v) SDS-PAGE gel and transferred to the PVDF membrane. The membranes were blocked in 5% (w/v) skim milk in Trisbuffered saline containing 0.1% Tween 20 for 1 hour and incubated at 4°C overnight with the primary antibody (listed in Table 2B) diluted in 5% skim milk.…”