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Cell Res:抗生素抗性基因可经反式剪接参与蛋白产生

  1. 反式剪接
  2. 抗性基因
  3. 抗生素

来源:上海生命科学研究院 2013-11-15 20:16

人ACAT1 56-kD异构体的编码RNA,是由跨染色体反式剪接成熟的内源性人ACAT1 mRNA与来自氨苄青霉素抗性重组质粒的外源性转录本通过又一轮反式剪接产生。

7月9日,国际知名学术期刊Cell Research在线发表了中科院上海生科院生物化学与细胞生物学研究所李伯良研究组题为Production of ACAT1 56-kDa isoform in human cells via trans-splicing involving the ampicillin resistance gene的研究论文,报道了来自氨苄青霉素抗性基因的外源转录本通过与内源人ACAT1 mRNA反式剪接并翻译产生人ACAT1 56-kD异构体的新机制。

抗生素抗性基因在自然环境和人体肠道广泛分布,正在成为影响公众安全的一个潜在威胁。某些抗生素抗性基因,如氨苄青霉素抗性基因,已作为最为常见的选择标记用于重组质粒中,并随之在近40年间广泛应用于科研、农业及医药等领域。RNA反式剪接能够将不同来源的转录本拼接起来,扩展并丰富了真核生物的转录组和蛋白质组。在此之前,来自重组质粒的外源性转录本与真核细胞内源性mRNA发生反式剪接的研究还未见有报道。

在研究酰基辅酶A:胆固醇酰基转移酶(Acyl-coenzyme A:cholesterol acyltransferase, ACAT)——胆固醇代谢平衡关键酶——的基因表达调控过程,研究人员胡光晶、陈佳、赵晓楠等发现,人ACAT1 56-kD异构体的编码RNA,是由跨染色体反式剪接成熟的内源性人ACAT1 mRNA与来自氨苄青霉素抗性重组质粒的外源性转录本通过又一轮反式剪接产生。同时,在正常人血液细胞和细胞系中均检测到氨苄青霉素抗性重组质粒来源转录本及其DNA片段。这一研究工作揭示了人ACAT1 56-kD异构体产生的独特分子机制,提出了来自重组质粒的外源转录本与人细胞中内源性mRNA发生反式剪接的模式,并表明外源性DNA对人体内细胞的基因表达影响可发生在DNA、RNA等多层次水平上。

该项研究工作得到了国家科技部、国家自然科学基金委、中国科学院的经费支持。

该研究工作内容被Cell Research选为2013年8月刊的封面论文。(生物谷Bioon.com)

生物谷推荐的英文摘要

Cell Research       doi:10.1038/cr.2013.86

Production of ACAT1 56-kDa isoform in human cells via trans-splicing involving the ampicillin resistance gene

Guang-Jing Hu1,*, Jia Chen1,*, Xiao-Nan Zhao1,*, Jia-Jia Xu1, Dong-Qing Guo1, Ming Lu1, Ming Zhu1, Ying Xiong1, Qin Li1, Catherine CY Chang2, Bao-Liang Song1, Ta-Yuan Chang2 and Bo-Liang Li1

Trans-splicing, a process involving the cleavage and joining of two separate transcripts, can expand the transcriptome and proteome in eukaryotes. Chimeric RNAs generated by trans-splicing are increasingly described in literatures. The widespread presence of antibiotic resistance genes in natural environments and human intestines is becoming an important challenge for public health. Certain antibiotic resistance genes, such as ampicillin resistance gene (Ampr), are frequently used in recombinant plasmids. Until now, trans-splicing involving recombinant plasmid-derived exogenous transcripts and endogenous cellular RNAs has not been reported. Acyl-CoA:cholesterol acyltransferase 1 (ACAT1) is a key enzyme involved in cellular cholesterol homeostasis. The 4.3-kb human ACAT1 chimeric mRNA can produce 50-kDa and 56-kDa isoforms with different enzymatic activities. Here, we show that human ACAT1 56-kDa isoform is produced from an mRNA species generated through the trans-splicing of an exogenous transcript encoded by the antisense strand of Ampr (asAmp) present in common Ampr-plasmids and the 4.3-kb endogenous ACAT1 chimeric mRNA, which is presumably processed through a prior event of interchromosomal trans-splicing. Strikingly, DNA fragments containing the asAmp with an upstream recombined cryptic promoter and the corresponding exogenous asAmp transcripts have been detected in human cells. Our findings shed lights on the mechanism of human ACAT1 56-kDa isoform production, reveal an exogenous-endogenous trans-splicing system, in which recombinant plasmid-derived exogenous transcripts are linked with endogenous cellular RNAs in human cells, and suggest that exogenous DNA might affect human gene expression at both DNA and RNA levels.

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