Department of Physiology and Bosch Institute, School of Medical Sciences, University of Sydney, NSW, Australia.
School of Chemical Engineering, University of New South Wales, Sydney, NSW, Australia.
Photochem Photobiol. 2022 Sep;98(5):1157-1166. doi: 10.1111/php.13615. Epub 2022 Mar 29.
The epidermis maintains a cellular calcium gradient that supports keratinocyte differentiation from its basal layers (low) to outer layers (high) leading to the development of the stratum corneum, which resists penetration of UV radiation. The calcium-sensing receptor (CaSR) expressed in keratinocytes responds to the calcium gradient with signals that promote differentiation. In this study, we investigated whether the CaSR is involved more directly in protection from UV damage in studies of human keratinocytes in primary culture and in mouse skin studied in vivo. siRNA-directed reductions in CaSR protein levels in human keratinocytes significantly reduced UV-induced direct cyclobutane pyrimidine dimers (CPD) by ~80% and oxidative DNA damage (8-OHdG) by ~65% compared with control transfected cells. Similarly, in untransfected cells, the CaSR negative modulator, NPS-2143 (500 nm), reduced UV-induced CPD and 8-OHdG by ~70%. NPS-2143 also enhanced DNA repair and reduced reactive oxygen species (ROS) by ~35% in UV-exposed keratinocytes, consistent with reduced DNA damage after UV exposure. Topical application of NPS-2143 also protected hairless Skh:hr1 mice from UV-induced CPD, oxidative DNA damage and inflammation, similar to the reductions observed in response to the well-known photoprotection agent 1,25(OH) D (calcitriol). Thus, negative modulators of the CaSR offer a new approach to reducing UV-induced skin damage.
表皮维持着细胞内钙离子梯度，支持角质形成细胞从基底层（低）向表层（高）分化，从而形成抵抗紫外线穿透的角质层。角质形成细胞中表达的钙敏感受体（CaSR）会对钙离子梯度做出反应，发出促进分化的信号。在这项研究中，我们研究了 CaSR 是否更直接参与了人原代角质形成细胞和体内研究的小鼠皮肤中对紫外线损伤的保护作用。siRNA 靶向降低人角质形成细胞中的 CaSR 蛋白水平，与对照转染细胞相比，紫外线诱导的直接环丁烷嘧啶二聚体（CPD）减少了约 80%，氧化 DNA 损伤（8-OHdG）减少了约 65%。同样，在未转染的细胞中，CaSR 负调节剂 NPS-2143（500nm）可使紫外线诱导的 CPD 和 8-OHdG 减少约 70%。NPS-2143 还可增强紫外线暴露的角质形成细胞中的 DNA 修复并减少约 35%的活性氧（ROS），这与紫外线暴露后 DNA 损伤减少一致。NPS-2143 的局部应用也可保护无毛 Skh:hr1 小鼠免受紫外线诱导的 CPD、氧化 DNA 损伤和炎症，这与对众所周知的光保护剂 1,25(OH) D（骨化三醇）的反应观察到的减少相似。因此，CaSR 的负调节剂为减少紫外线引起的皮肤损伤提供了一种新方法。
