Weak Ultraviolet B Enhances the Mislocalization of Claudin-1 Mediated by Nitric Oxide and Peroxynitrite Production in Human Keratinocyte-Derived HaCaT Cells

Abstract

A tight junction (TJ) makes a physical barrier in the epidermal cells of skin. Ultraviolet (UV) light may disrupt the TJ barrier, but the mechanism has not been well clarified. Weak UVB (5 mJ/cm2) caused mislocalization of claudin-1 (CLDN1), a component of the TJ strand, and disruption of TJ barrier in human keratinocyte-derived HaCaT cells. The UVB-induced mislocalization of CLDN1 was inhibited by monodansylcadaverine (MDC), a clathrin-dependent endocytosis inhibitor, suggesting that UVB enhances the internalization of CLDN1. Transepidermal electrical resistance and paracellular flux of lucifer yellow, a fluorescent hydrophilic marker, were rescued by MDC. UVB changed neither the total nor phosphorylation levels of CLDN1, but it increased both mono-ubiquitination and tyrosine nitration levels of CLDN1. Fluorescence measurements revealed that UVB increased intracellular free Ca2+, nitric oxide (NO), and peroxynitrite contents, which were inhibited by Opsin2 (OPN2) siRNA, suggesting that OPN2 functions as a UVB sensor. The effects of UVB were inhibited by an antagonist of transient receptor potential type vanilloid 1 (TRPV1) and Ca2+ chelator. Both NO donor and peroxynitrite donor induced the mislocalization of CLDN1 and disruption of TJ barrier, which were rescued by a NO synthase (NOS) inhibitor and a peroxynitrite scavenger. Weak UVB irradiation induced the disruption of TJ barrier mediated by mislocalization of CLDN1 in HaCaT cells. The OPN2/TRPV1/NOS signaling pathway may be a novel target for preventing destruction of the TJ barrier by UVB irradiation.

Protective Effects of Ethanol Extract of Brazilian Green Propolis and Apigenin against Weak Ultraviolet Ray-B-Induced Barrier Dysfunction via Suppressing Nitric Oxide Production and Mislocalization of Claudin-1 in HaCaT Cells

“…Once the weak UVB irradiated the cells, the generation of reactive nitrogen species (RNS) was stimulated, which induced mislocalization of CLND1 [ 5 ]. Next, the effects on RNS generation were investigated using specific probes for Ca 2+ influx, nitrogen oxide (NO) production, and peroxynitrite production, which is a more reactive form of RNS.…”

“…A severe level of ultraviolet ray-B (UVB) irradiation causes reactive oxygen species (ROS), reactive nitrogen species (RNS), and DNA damage, resulting in the dysfunction of the skin barrier and an elevation of risk factors for skin cancer [ 6 ]. In contrast, non-cytotoxic “weak” UVB irradiation stimulates RNS generation, but not ROS, leading to barrier dysfunction associated with the mislocalization of CLDN1 in our previous report [ 5 ]. Since our skin is constantly exposed to sunlight throughout our lives, an effective protection strategy is needed to maintain skin health against weak UVB.…”

“…Since these reports indicate that the expression level of CLDN1 decreased in the skin with atopic dermatitis [ 2 ] and CLDN1 knockout mice showed skin barrier dysfunction [ 3 ], CLDN1 is considered as a main component for the TJ barriers in the skin among over 20 subtypes of CLDNs. Our recent studies suggest the expression level and the cellular localization of CLDN1 might be related closely to the integrity of the TJ barrier in the skin [ 4 , 5 ].…”

The Role of Cell Adhesion Molecule 1 (CADM1) in Cutaneous Malignancies

“…Overexpression of CADM1 shows an increased Claudin-1 expression, while the silencing CADM1 improves the intestinal barrier function. Claudin-1 is responsible for barrier function in the skin [ 76 , 77 ], therefore CADM1 in keratinocytes is expected to exhibit a positive regulation in the skin barrier and have a beneficial impact on skin barrier-related diseases [ 78 ]. However, the actual impact of CADM1 in epidermal barrier function remains unclear.…”

Skin Epidermis and Barrier Function

“…More importantly, treatment with recombinant TNC polypeptide increased collagen expression by activating the transforming growth factor- β (TGF-β) signaling pathway. Kobayashi et al [ 12 ] showed that UVB enhances the mis-localization of claudin-1 through NO and peroxynitrite production in a human keratinocyte cell line, which can explain the weakening of skin barrier and the deterioration of skin condition upon exposure to UVB. Lee et al [ 13 ] discovered that a synthetic retinoid, seletinoid G, is effective in improving skin barrier function, which they purported to be due to its wound-healing effects.…”