Evidence that tRNA modifying enzymes are important in vivo targets for 5-fluorouracil in yeast
Evidence that tRNA modifying enzymes are important in vivo targets for 5-fluorouracil in yeast
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DOI：
10.1261/rna.966208
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发表时间：
2008-04-01
期刊：
影响因子：
4.5
通讯作者：
Ronne, Hans
中科院分区：
文献类型：
--
作者：
Gustavsson, Marie;Ronne, Hans
我们已经筛选了一组单倍体酵母基因敲除菌株，以提高对5-氟尿嘧啶(5-FU)的敏感性。共检出138株5-FU敏感菌株。影响rRNA和tRNA成熟的突变体对5-FU特别敏感，其中tRNA甲基化突变体trm10最为敏感。这很耐人寻味，因为trm10和许多其他tRNA修饰突变体一样，在正常条件下缺乏表型。然而，非必需tRNA修饰酶的双突变通常是温度敏感的，这是由于低修饰的tRNA不稳定所致。因此，我们测试了我们的突变体对5-FU的敏感性是否受温度的影响。我们发现，在38℃时，5-FU对tRNA修饰突变体的细胞毒作用显著增强。此外，tRNA修饰突变体在温度敏感性和对5-FU的敏感性方面表现出类似的合成相互作用。提出了一个模型，说明5-FU如何通过减少tRNA修饰的数量来杀死这些突变体，从而破坏tRNA的稳定。最后，我们发现野生型细胞对较高浓度的5-FU也是温度敏感的。这表明tRNA失稳导致了5-FU对野生型细胞的细胞毒作用，并可能解释了为什么热疗可以增强5-FU在癌症治疗中的作用。
We have screened a collection of haploid yeast knockout strains for increased sensitivity to 5-fluorouracil (5-FU). A total of 138 5-FU sensitive strains were found. Mutants affecting rRNA and tRNA maturation were particularly sensitive to 5-FU, with the tRNA methylation mutant trm10 being the most sensitive mutant. This is intriguing since trm10, like many other tRNA modification mutants, lacks a phenotype under normal conditions. However, double mutants for nonessential tRNA modification enzymes are frequently temperature sensitive, due to destabilization of hypomodified tRNAs. We therefore tested if the sensitivity of our mutants to 5-FU is affected by the temperature. We found that the cytotoxic effect of 5-FU is strongly enhanced at 38 C for tRNA modification mutants. Furthermore, tRNA modification mutants show similar synthetic interactions for temperature sensitivity and sensitivity to 5-FU. A model is proposed for how 5-FU kills these mutants by reducing the number of tRNA modifications, thus destabilizing tRNA. Finally, we found that also wild-type cells are temperature sensitive at higher concentrations of 5-FU. This suggests that tRNA destabilization contributes to 5-FU cytotoxicity in wild-type cells and provides a possible explanation why hyperthermia can enhance the effect of 5-FU in cancer therapy.