Maytin E V, Wimberly J M, Anderson R R
Department of Dermatology, Harvard Medical School, Massachusetts General Hospital, Boston 02114.
J Invest Dermatol. 1990 Dec;95(6):635-42. doi: 10.1111/1523-1747.ep12514303.
Protective responses of normal human epidermal keratinocytes in culture, after exposure to elevated temperatures ("heat shock"), were examined. Cell viability, measured 24-48 h after a 20-min heat challenge at temperatures between 37 degrees C and 54 degrees C, declined sharply within a narrow 2 degrees-3 degrees C range. However, conditioning with a mild thermal pretreatment (40 degrees C or 42 degrees C for 1 h) protected the keratinocytes against a subsequent heat challenge. This induced thermotolerance was apparent when cells were challenged at 1, 3, and 6 h after the thermal pre-treatment, but disappeared by 24 h. Heating conditions that induce thermotolerance also stimulated the synthesis of heat-shock proteins (hsp) in these cells. Inductions of prominent 35S-methionine labeled bands at 70, 78, and 90 kDa were observed. However, the increases in synthesis of these heat-shock proteins did not correlate well with thermotolerance, because large increases were also observed at certain elevated temperatures that did not produce improved survival. Keratins observed in these cells (50 and 58 kDa classes) were not induced by heat shock. The development of thermotolerance, and the induction of hsp, were both completely blocked by 3'-deoxyadenosine (cordycepin), an inhibitor of newly synthesized messenger RNA, but not by adenosine, the normal analog. While heat-inducible mRNA apparently mediate some function important for the development of thermotolerance, the nature of that role remains speculative. Overall, our findings establish the existence of a functional thermal protective mechanism in human keratinocytes that appears to require the synthesis of new mRNA.
研究了培养的正常人表皮角质形成细胞在暴露于高温（“热休克”）后的保护反应。在37℃至54℃之间进行20分钟热刺激后24 - 48小时测量细胞活力，在狭窄的2℃ - 3℃范围内急剧下降。然而，用温和的热预处理（40℃或42℃处理1小时）可保护角质形成细胞免受随后的热刺激。当细胞在热预处理后1、3和6小时受到刺激时，这种诱导的耐热性很明显，但在24小时时消失。诱导耐热性的加热条件也刺激了这些细胞中热休克蛋白（hsp）的合成。观察到在70、78和90 kDa处有明显的35S - 甲硫氨酸标记条带的诱导。然而，这些热休克蛋白合成的增加与耐热性并没有很好的相关性，因为在某些不会提高存活率的高温下也观察到了大幅增加。在这些细胞中观察到的角蛋白（50和58 kDa类别）不会因热休克而诱导。耐热性的发展和hsp的诱导都被3'-脱氧腺苷（虫草素）完全阻断，3'-脱氧腺苷是新合成信使RNA的抑制剂，但正常类似物腺苷则不会。虽然热诱导的mRNA显然介导了对耐热性发展很重要的某些功能，但其作用的性质仍具有推测性。总体而言，我们的研究结果证实了人类角质形成细胞中存在一种功能性热保护机制，该机制似乎需要新mRNA的合成。
