Hayashi Masanobu, Hamasu Taku, Endoh Daiji, Kawana Ai, Matsumoto Minako, Okui Toyo
Department of Veterinary Radiology, School of Veterinary Medicine, Rakuno Gakuen University, Ebetsu, Japan.
J Vet Med Sci. 2004 Oct;66(10):1177-82. doi: 10.1292/jvms.66.1177.
A fibroblast cell line derived from LEC rat was approximately twofold more sensitive to heat treatment at 45 degrees C than were that from WKAH rat in terms of heating time required to attain 50% loss of survival in a colony forming assay. The present study was carried out for understanding the mechanism underlying the higher sensitivity of LEC rat cells to heat treatment. Although apoptosis was not found in WKAH rat cells, the percentages of apoptotic cells in LEC rat cells significantly increased after heat treatment. LEC rat cells showed significantly lower sensitivity in induction of cell death and apoptosis to ceramide, a lipid signaling molecule that is associated with heat-induced apoptosis, than did WKAH rat cells. SP600125, an inhibitor of JNK suppressed the induction of cell death in both heated LEC and WKAH rat cells, but SB203580, an inhibitor of p38 mapk, did not. The relative surviving fractions of heated LEC and WKAH rat cells in the presence of both SB203580 and SP600125 were higher than those of cells in the presence of SP600125 alone. The amounts of hsp70 protein in WKAH rat cells increased from 4 to 12 hr after heat treatment, but did not in LEC rat cells. These results suggest that higher thermosensitivity in the fibroblast cell line from LEC rat is due to low inducibility of hsp70 protein after heat treatment.
从LEC大鼠衍生的成纤维细胞系在集落形成试验中，达到50%存活丧失所需的加热时间方面，比从WKAH大鼠衍生的细胞系对45摄氏度热处理的敏感性高约两倍。本研究旨在了解LEC大鼠细胞对热处理更高敏感性的潜在机制。虽然在WKAH大鼠细胞中未发现细胞凋亡，但热处理后LEC大鼠细胞中的凋亡细胞百分比显著增加。与热诱导凋亡相关的脂质信号分子神经酰胺诱导细胞死亡和凋亡时，LEC大鼠细胞的敏感性明显低于WKAH大鼠细胞。JNK抑制剂SP600125抑制加热后的LEC和WKAH大鼠细胞中的细胞死亡诱导，但p38丝裂原活化蛋白激酶抑制剂SB203580则没有。在同时存在SB203580和SP600125的情况下，加热后的LEC和WKAH大鼠细胞的相对存活分数高于仅存在SP600125时的细胞。热处理后4至12小时，WKAH大鼠细胞中的hsp70蛋白量增加，但LEC大鼠细胞中则没有。这些结果表明，LEC大鼠成纤维细胞系中较高的热敏感性是由于热处理后hsp70蛋白的诱导性较低。
