Baba T, Hanada K, Hashimoto I
Department of Dermatology, Hirosaki University School of Medicine, Japan.
J Dermatol Sci. 1996 Apr;12(1):18-23. doi: 10.1016/0923-1811(95)00452-1.
The responsibility of ultraviolet B (UVB) radiation for the induction of apoptosis in epidermal cells in vitro and in vivo was examined. Using cultured mouse keratinocytes, PAM212 cells, the morphological development of apoptotic cells (AC) after UVB irradiation was observed, and their DNA status was also examined. In addition, histochemical analysis was performed to establish whether the UVB-mediated sunburn cells (SBC) were AC or not. The cultured cells exposed to UVB showed the morphological characteristics of AC, and the electrophoresis of DNA isolated from these cells showed characteristic fragmentation, i.e. 'DNA ladder'. DNA fragmentation was detectable with UVB doses of more than 50 mJ/cm2, and it appeared 12 h after irradiation, indicating endonuclease-mediated DNA damage. In vivo experimentation using the TdT-mediated dUTP-biotin nick end labeling method (TUNEL) for detection of AC showed scattered positive cells in the basal layer of the UVB-irradiated mouse ear skin. The distributed pattern of the TUNEL-positive cells was similar to that of SBCs. These findings suggest that UVB is a causative factor of apoptosis in the epidermal cells, and that SBC is formed as a result of the apoptosis.
研究了紫外线B（UVB）辐射在体外和体内诱导表皮细胞凋亡中的作用。使用培养的小鼠角质形成细胞、PAM212细胞，观察UVB照射后凋亡细胞（AC）的形态学变化，并检测其DNA状态。此外，进行组织化学分析以确定UVB介导的晒伤细胞（SBC）是否为AC。暴露于UVB的培养细胞表现出AC的形态学特征，从这些细胞中分离的DNA电泳显示出特征性片段化，即“DNA梯带”。UVB剂量超过50 mJ/cm2时可检测到DNA片段化，且在照射后12小时出现，表明存在核酸内切酶介导的DNA损伤。使用TdT介导的dUTP生物素缺口末端标记法（TUNEL）在体内检测AC，结果显示在UVB照射的小鼠耳部皮肤基底层有散在的阳性细胞。TUNEL阳性细胞的分布模式与SBC相似。这些发现表明UVB是表皮细胞凋亡的致病因素，且SBC是细胞凋亡的结果。
