کد مقاله | کد نشریه | سال انتشار | مقاله انگلیسی | نسخه تمام متن |
---|---|---|---|---|
2812329 | 1569300 | 2007 | 17 صفحه PDF | دانلود رایگان |
![عکس صفحه اول مقاله: Seemingly Neutral Polymorphic Variants May Confer Immunity to Splicing-Inactivating Mutations: A Synonymous SNP in Exon 5 of MCAD Protects from Deleterious Mutations in a Flanking Exonic Splicing Enhancer Seemingly Neutral Polymorphic Variants May Confer Immunity to Splicing-Inactivating Mutations: A Synonymous SNP in Exon 5 of MCAD Protects from Deleterious Mutations in a Flanking Exonic Splicing Enhancer](/preview/png/2812329.png)
The idea that point mutations in exons may affect splicing is intriguing and adds an additional layer of complexity when evaluating their possible effects. Even in the best-studied examples, the molecular mechanisms are not fully understood. Here, we use patient cells, model minigenes, and in vitro assays to show that a missense mutation in exon 5 of the medium-chain acyl-CoA dehydrogenase (MCAD) gene primarily causes exon skipping by inactivating a crucial exonic splicing enhancer (ESE), thus leading to loss of a functional protein and to MCAD deficiency. This ESE functions by antagonizing a juxtaposed exonic splicing silencer (ESS) and is necessary to define a suboptimal 3′ splice site. Remarkably, a synonymous polymorphic variation in MCAD exon 5 inactivates the ESS, and, although this has no effect on splicing by itself, it makes splicing immune to deleterious mutations in the ESE. Furthermore, the region of MCAD exon 5 that harbors these elements is nearly identical to the exon 7 region of the survival of motor neuron (SMN) genes that contains the deleterious silent mutation in SMN2, indicating a very similar and finely tuned interplay between regulatory elements in these two genes. Our findings illustrate a mechanism for dramatic context-dependent effects of single-nucleotide polymorphisms on gene-expression regulation and show that it is essential that potential deleterious effects of mutations on splicing be evaluated in the context of the relevant haplotype.
Journal: - Volume 80, Issue 3, March 2007, Pages 416–432