Schreck S, Panozzo J, Milton J, Libertin C R, Woloschak G E
Argonne National Laboratory, Center for Mechanistic Biology and Biotechnology, IL 60439-4833, USA.
Photochem Photobiol. 1995 Apr;61(4):378-82. doi: 10.1111/j.1751-1097.1995.tb08626.x.
Previous studies have shown that cellular stress agents such as UV radiation induce transcription from the long terminal repeat (LTR) of the human immunodeficiency virus (HIV). Using HeLa cells stably transfected with the HIV-LTR sequence, which transcriptionally drives the chloramphenicol acetyl transferase (CAT) reporter gene, we examined the effects of multiple exposures to UVC (254 nm) on HIV-LTR-CAT expression. Low doses (< or = 5 J m-2) had no effect on CAT expression, but up to 29-fold induction was observed with 10 J m-2 when cells were harvested 48 h after completion of the exposure. Little difference was noted in induction levels when cells were exposed to one 25 J m-2 dose, viable cells were harvested at 24 h, 48 h or 72 h, and cell lysates were assayed for CAT expression. Two sequential 12.5 J m-2 exposures, given 24 h apart, resulted in an additive effect on CAT expression; these two exposures produced CAT activity equivalent to that induced following a single 25 J m-2 dose. This additive effect was not evident at the lower doses (< or = 5 J m-2) or at the higher doses. Maximal induction was observed using doses from 25 to 37.5 J m-2. Multiple exposures with either the low (< or = 5 J m-2) or high doses (> 25 J m-2) did not result in an additive effect.(ABSTRACT TRUNCATED AT 250 WORDS)
先前的研究表明，紫外线辐射等细胞应激因子可诱导人类免疫缺陷病毒（HIV）长末端重复序列（LTR）的转录。我们使用稳定转染了HIV-LTR序列的HeLa细胞，该序列转录驱动氯霉素乙酰转移酶（CAT）报告基因，研究了多次暴露于UVC（254 nm）对HIV-LTR-CAT表达的影响。低剂量（≤5 J m-2）对CAT表达无影响，但在暴露结束后48小时收获细胞时，10 J m-2可观察到高达29倍的诱导。当细胞暴露于一次25 J m-2剂量，在24小时、48小时或72小时收获活细胞，并检测细胞裂解物中的CAT表达时，诱导水平差异不大。相隔24小时进行的两次连续12.5 J m-2暴露对CAT表达产生累加效应；这两次暴露产生的CAT活性与单次25 J m-2剂量诱导的活性相当。这种累加效应在较低剂量（≤5 J m-2）或较高剂量时不明显。使用25至37.5 J m-2的剂量观察到最大诱导。低剂量（≤5 J m-2）或高剂量（>25 J m-2）的多次暴露均未产生累加效应。（摘要截短于250字）
