Splicing defects in the ataxia-telangiectasia gene, ATM:: Underlying mutations and consequences
Splicing defects in the ataxia-telangiectasia gene, ATM:: Underlying mutations and consequences
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DOI：
10.1086/302418
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发表时间：
1999-06-01
影响因子：
9.8
通讯作者：
Concannon, P
中科院分区：
文献类型：
--
作者：
Teraoka, SN;Telatar, M;Concannon, P
通过蛋白质截断试验以及随后对基因组DNA的序列分析，在共济失调 - 毛细血管扩张症（AT）患者的ATM基因一系列新突变中，导致剪接缺陷的突变占相当大的比例（30/62 [48%]）。不到一半的剪接突变涉及经典的AG剪接受体位点或GT剪接供体位点。更高比例的突变发生在不太严格保守的位点，包括外显子最后一个核苷酸的沉默突变、共有剪接位点中除保守的AG和GT之外的核苷酸突变，以及在内含子或外显子中产生剪接受体或剪接供体位点。这些剪接突变导致了多种后果，包括外显子跳跃，以及在较小程度上的内含子保留、隐蔽剪接位点的激活或新剪接位点的产生。此外，12个无义突变中的5个和1个错义突变与发生突变的外显子在cDNA中的缺失有关。在任何鉴定出剪接突变的AT细胞系中，通过蛋白质印迹法均未检测到ATM蛋白。在正常对照以及在基因组DNA中未发现潜在缺陷的患者中，也观察到了几例外显子跳跃的情况，这提示在没有同时鉴定出基因组突变的情况下，对在ATM cDNA中观察到的外显子缺失进行解释时要谨慎。
Mutations resulting in defective splicing constitute a significant proportion (30/62 [48%]) of a new series of mutations in the ATM gene in patients with ataxia-telangiectasia (AT) that were detected by the protein-truncation assay followed by sequence analysis of genomic DNA. Fewer than half of the splicing mutations involved the canonical AG splice-acceptor site or GT splice-donor site. A higher percentage of mutations occurred at less stringently conserved sites, including silent mutations of the last nucleotide of exons, mutations in nucleotides other than the conserved AG and GT in the consensus splice sites, and creation of splice-acceptor or splice-donor sites in either introns or exons. These splicing mutations led to a variety of consequences, including exon skipping and, to a lesser degree, intron retention, activation of cryptic splice sites, or creation of new splice sites. In addition, 5 of 12 nonsense mutations and 1 missense mutation were associated with deletion in the cDNA of the exons in which the mutations occurred. No ATM protein was detected by western blotting in any AT cell line in which splicing mutations were identified. Several cases of exon skipping in both normal controls and patients for whom no underlying defect could be found in genomic DNA were also observed, suggesting caution in the interpretation of exon deletions observed in ATM cDNA when there is no accompanying identification of genomic mutations.