Higuchi M, Maas S, Single F N, Hartner J, Rozov A, Burnashev N, Feldmeyer D, Sprengel R, Seeburg P H
Department of Molecular Neurobiology, Max-Planck Institute for Medical Research, Heidelberg, Germany.
Nature. 2000 Jul 6;406(6791):78-81. doi: 10.1038/35017558.
RNA editing by site-selective deamination of adenosine to inosine alters codons and splicing in nuclear transcripts, and therefore protein function. ADAR2 (refs 7, 8) is a candidate mammalian editing enzyme that is widely expressed in brain and other tissues, but its RNA substrates are unknown. Here we have studied ADAR2-mediated RNA editing by generating mice that are homozygous for a targeted functional null allele. Editing in ADAR2-/- mice was substantially reduced at most of 25 positions in diverse transcripts; the mutant mice became prone to seizures and died young. The impaired phenotype appeared to result entirely from a single underedited position, as it reverted to normal when both alleles for the underedited transcript were substituted with alleles encoding the edited version exonically. The critical position specifies an ion channel determinant, the Q/R site, in AMPA (alpha-amino-3-hydroxy-5-methyl-4-isoxazole propionate) receptor GluR-B pre-messenger RNA. We conclude that this transcript is the physiologically most important substrate of ADAR2.
通过腺苷向肌苷的位点选择性脱氨作用进行的RNA编辑会改变核转录本中的密码子和剪接，进而影响蛋白质功能。ADAR2（参考文献7、8）是一种候选的哺乳动物编辑酶，在大脑和其他组织中广泛表达，但其RNA底物尚不清楚。在此，我们通过生成靶向功能性无效等位基因纯合的小鼠来研究ADAR2介导的RNA编辑。在ADAR2基因敲除小鼠中，多种转录本中25个位置的大多数编辑水平都大幅降低；突变小鼠容易癫痫发作且寿命较短。这种受损表型似乎完全由一个编辑不足的位置导致，当该编辑不足转录本的两个等位基因在编码外显子的位置被编码编辑版本的等位基因取代时，表型恢复正常。关键位置在AMPA（α-氨基-3-羟基-5-甲基-4-异恶唑丙酸）受体GluR-B前体信使RNA中指定了一个离子通道决定因素，即Q/R位点。我们得出结论，该转录本是ADAR2在生理上最重要的底物。
