Maytin E V, Wimberly J M, Kane K S
Cutaneous Biology Research Center, Massachusetts General Hospital, Boston 02114.
J Invest Dermatol. 1994 Oct;103(4):547-53. doi: 10.1111/1523-1747.ep12396274.
The ability of heat shock to induce functional protection against ultraviolet B (UVB) light was examined in keratinocytes cultured from human skin. Cell death, measured with fluorescent vital dyes, increased in a UVB dose-dependent manner (LD50 approximately 20-60 mJ/cm2). However, a 60-min heat shock at 40 degrees C or 42 degrees C, administered several hours before UVB irradiation, reduced cell death by 2.0-2.5 times. Inducible protection took time to develop, with an optimal interval of approximately 6 h between heat and UVB exposures. Heat-inducible protection was completely blocked if either cordycepin (3'-deoxyadenosine), to inhibit mRNA synthesis, or cycloheximide, to inhibit protein synthesis, were present during the heating period. To determine whether apoptosis might be involved in UVB-induced keratinocyte death in this system, evidence for endonuclease activity was sought via in situ enzymatic labeling with terminal deoxynucleotidyl transferase and biotinylated-dUTP. Labeled nuclei were detected in UVB-irradiated cultures, and heat pretreatment at 6 h prior to UVB exposure (< 60 mJ/cm2) resulted in a 50% reduction in labeled nuclei. Overall, the data show that UVB-induced cell death in human keratinocyte cultures is attenuated by a heat-inducible mechanism that requires ongoing synthesis of mRNA and protein.
在从人皮肤培养的角质形成细胞中检测了热休克诱导针对紫外线B（UVB）的功能保护的能力。用荧光活性染料测量的细胞死亡以UVB剂量依赖性方式增加（半数致死剂量约为20 - 60 mJ/cm²）。然而，在UVB照射前数小时给予40℃或42℃的60分钟热休克，可使细胞死亡减少2.0 - 2.5倍。诱导性保护需要时间来发展，热暴露和UVB暴露之间的最佳间隔约为6小时。如果在加热期间存在抑制mRNA合成的虫草素（3'-脱氧腺苷）或抑制蛋白质合成的环己酰亚胺，则热诱导的保护作用会被完全阻断。为了确定在该系统中UVB诱导的角质形成细胞死亡是否可能涉及细胞凋亡，通过用末端脱氧核苷酸转移酶和生物素化dUTP进行原位酶标记来寻找核酸内切酶活性的证据。在UVB照射的培养物中检测到标记的细胞核，并且在UVB暴露（<60 mJ/cm²）前6小时进行热预处理导致标记细胞核减少50％。总体而言，数据表明，人角质形成细胞培养物中UVB诱导的细胞死亡通过一种热诱导机制而减弱，该机制需要mRNA和蛋白质的持续合成。
