Redefinition of exon 7 in the COL1A1 gene of type I collagen by an intron 8 splice-donor-site mutation in a form of osteogenesis imperfecta:: Influence of intron splice order on outcome of splice-site mutation
Redefinition of exon 7 in the COL1A1 gene of type I collagen by an intron 8 splice-donor-site mutation in a form of osteogenesis imperfecta:: Influence of intron splice order on outcome of splice-site mutation
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DOI：
10.1086/302512
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发表时间：
1999-08-01
影响因子：
9.8
通讯作者：
Byers, PH
中科院分区：
文献类型：
--
作者：
Schwarze, U;Starman, BJ;Byers, PH
大多数剪接位点突变导致有限的产物，包括外显子跳变，使用隐剪接受体或供体位点，以及内含子包含。在COL1A1基因的内含子8剪接供体位点，我们发现了一个G+1—> a过渡，导致突变等位基因产生了几个剪接产物。其中一个上游外显子7延长了96 nt，另一个保留了内含子8或内含子7和8，一个外显子8被跳过，一个使用了外显子8的神秘供体位点。为了确定外显子-7重定义可能发生的机制，我们通过使用内含子/外显子引物对扩增外显子5和外显子10之间的前体核mRNA区域，检查了突变区域内内含子去除的顺序。内含子5、6和9的去除速度很快。在正常基因中，去除内含子8通常先于去除内含子7，尽管在一小部分拷贝中，顺序是相反的。异常产物的比例表明，外显子7重定义、内含子7 +内含子8和外显子8跳过都是受损快速途径的产物，而内含子8包含产物是使用慢速内含子7优先途径产生的。极低丰度的隐式外显子8供体位点产物可能来自任一途径。这些结果表明，与突变的存在无关，前mrna对这两种途径有承诺，并且内含子去除的顺序和速率是剪接位点突变结果的重要决定因素，并可能解释一些不寻常的改变。
Most splice-site mutations lead to a limited array of products, including exon skipping, use of cryptic splice-acceptor or -donor sites, and intron inclusion. At the intron 8 splice-donor site of the COL1A1 gene, we identified a G+1-->A transition that resulted in the production of several splice products from the mutant allele. These included one in which the upstream exon 7 was extended by 96 nt, others in which either intron 8 or introns 7 and 8 were retained, one in which exon 8 was skipped, and one that used a cryptic donor site in exon 8. To determine the mechanism by which exon-7 redefinition might occur, we examined the order of intron removal in the region of the mutation by using intron/exon primer pairs to amplify regions of the precursor nuclear mRNA between exon 5 and exon 10. Removal of introns 5, 6, and 9 was rapid. Removal of intron 8 usually preceded removal of intron 7 in the normal gene, although, in a small proportion of copies, the order was reversed. The proportion of abnormal products suggested that exon 7 redefinition, intron 7 plus intron 8 inclusion, and exon 8 skipping all represented products of the impaired rapid pathway, whereas the intron-8 inclusion product resulted from use of the slow intron 7-first pathway. The very low-abundance cryptic exon 8 donor site product could have arisen from either pathway. These results suggest that there is commitment of the pre-mRNA to the two pathways, independent of the presence of the mutation, and that the order and rate of intron removal are important determinants of the outcome of splice-site mutations and may explain some unusual alterations.