Department of Dermatology, Seoul National University College of Medicine, Seoul, Republic of Korea; Department of Biomedical Sciences, Seoul National University Graduate School, Seoul, Republic of Korea; Institute of Human-Environment Interface Biology, Medical Research Center, Seoul National University, Seoul, Republic of Korea.
Department of Dermatology, Seoul National University College of Medicine, Seoul, Republic of Korea; Institute of Human-Environment Interface Biology, Medical Research Center, Seoul National University, Seoul, Republic of Korea.
J Dermatol Sci. 2024 Nov;116(2):70-77. doi: 10.1016/j.jdermsci.2024.09.005. Epub 2024 Sep 27.
Overexposure to ultraviolet (UV) radiation accelerates skin aging, resulting in wrinkle formation, reduced skin elasticity, and hyperpigmentation. UV irradiation induces increased matrix metalloproteinases (MMPs) that degrade collagen in the extracellular matrix. Skin aging is also accompanied by epigenetic alterations such as promoter methylation by DNA methyltransferases, leading to the activation or suppression of gene expression. Although carnitine acetyltransferase (CRAT) is implicated in aging, the effect of UV on the expression of CRAT and regulatory mechanisms of UV-induced MMP-1 expression remain unknown.
We investigated changes in CRAT expression upon UV irradiation and its effect on MMP-1 expression.
Primary human dermal fibroblasts were UV irradiated with either control or 5-AZA-dC. CRAT knockdown or overexpression was performed to investigate its effect on MMP-1 expression. The mRNA level was analyzed by quantitative real-time PCR, and protein level by western blotting.
The expression of CRAT was decreased in UV-irradiated human skin in vivo and in human dermal fibroblasts in vitro. CRAT was downregulated upon UV irradiation by hypermethylation, and treatment with 5-Aza-2'-deoxycytidine, a DNA methyltransferase inhibitor, reversed UV-induced downregulation of CRAT. CRAT knockdown activated the JNK, ERK, and p38 MAPK signaling pathways, which increased MMP-1 expression. Stable overexpression of CRAT alleviated UV-induced MMP-1 induction.
CRAT downregulation caused by promoter hypermethylation may play an important role in UV-induced skin aging via upregulation of MMP-1 expression.
过度暴露于紫外线 (UV) 辐射会加速皮肤衰老，导致皱纹形成、皮肤弹性降低和色素沉着过度。UV 照射会诱导基质金属蛋白酶 (MMPs) 的增加，从而降解细胞外基质中的胶原蛋白。皮肤衰老还伴随着表观遗传改变，如 DNA 甲基转移酶引起的启动子甲基化，导致基因表达的激活或抑制。虽然肉碱乙酰转移酶 (CRAT) 与衰老有关，但 UV 对 CRAT 表达的影响及其对 UV 诱导的 MMP-1 表达的调控机制尚不清楚。
研究 CRAT 表达在 UV 照射下的变化及其对 MMP-1 表达的影响。
用对照或 5-AZA-dC 对原代人真皮成纤维细胞进行 UV 照射。进行 CRAT 敲低或过表达，以研究其对 MMP-1 表达的影响。通过定量实时 PCR 分析 mRNA 水平，通过 Western blot 分析蛋白水平。
体内人皮肤和体外人真皮成纤维细胞中，CRAT 的表达在 UV 照射后降低。CRAT 由于 hypermethylation 在 UV 照射后下调，并用 DNA 甲基转移酶抑制剂 5-Aza-2'-脱氧胞苷处理可逆转 CRAT 的 UV 诱导下调。CRAT 敲低激活了 JNK、ERK 和 p38 MAPK 信号通路，增加了 MMP-1 的表达。CRAT 的稳定过表达减轻了 UV 诱导的 MMP-1 诱导。
启动子 hypermethylation 引起的 CRAT 下调可能通过上调 MMP-1 表达在 UV 诱导的皮肤衰老中起重要作用。
