A comprehensive functional characterization of BRCA2 variants associated with Fanconi anemia using mouse ES cell-based assay
A comprehensive functional characterization of BRCA2 variants associated with Fanconi anemia using mouse ES cell-based assay
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DOI：
10.1182/blood-2010-12-324541
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发表时间：
2011-09-01
期刊：
影响因子：
20.3
通讯作者：
Sharan, Shyam K.
中科院分区：
文献类型：
--
作者：
Biswas, Kajal;Das, Ranabir;Sharan, Shyam K.
人类乳腺癌易感基因BRCA 2的双等位基因突变与范可尼贫血相关，这意味着一些遗传了BRCA 2的2种有害变体的人能够存活，尽管已经确定BRCA 2对小鼠的生存力是必不可少的。一种这样的变体IVS 7 + 2 T> G由于外显子7的跳跃而导致过早的蛋白质截短。令人惊讶的是，IVS 7 + 2 T> G纯合子或复合杂合子的人出生时存活，但死于与范可尼贫血相关的恶性肿瘤。使用基于小鼠胚胎干细胞的功能测定，我们发现IVS 7 + 2 T> G等位基因产生缺少外显子4-7的选择性剪接转录物，编码具有105个氨基酸的内部缺失的框内BRCA 2蛋白（BRCA 2（Delta 105））。我们证明，BRCA 2（三角洲105）是精通同源重组介导的DNA修复不同的功能测定。在正常和白血病细胞中对这种转录本的评估表明，BRCA 2（Delta 105）可能有助于遗传这种突变的人的生存能力。在这项研究中，我们还鉴定了5种其他BRCA 2变体，发现其中3种（p.L2510P、p.R2336H和p.W2626C）是有害的，2种（p.I2490T和p.K2729N）可能是中性的。这些研究对于了解未分类的BRCA 2变体的功能意义非常重要。（血。2011;118（9）：2430-2442）
Biallelic mutations in the human breast cancer susceptibility gene, BRCA2, are associated with Fanconi anemia, implying that some persons who inherit 2 deleterious variants of BRCA2 are able to survive even though it is well established that BRCA2 is indispensable for viability in mice. One such variant, IVS7 + 2T > G, results in premature protein truncation because of skipping of exon 7. Surprisingly, the persons who are either IVS7 + 2T > Ghomozygous or compound heterozygous are born alive but die of malignancy associated with Fanconi anemia. Using a mouse embryonic stem cell-based functional assay, we found that the IVS7 + 2T > G allele produces an alternatively spliced transcript lacking exons 4-7, encoding an in-frame BRCA2 protein with an internal deletion of 105 amino acids (BRCA2(Delta 105)). We demonstrate that BRCA2(Delta 105) is proficient in homologous recombination-mediated DNA repair as measured by different functional assays. Evaluation of this transcript in normal and leukemia cells suggests that BRCA2(Delta 105) may contribute to the viability of persons inheriting this mutation. In this study, we have also characterized 5 other BRCA2 variants and found 3 of these (p.L2510P, p.R2336H, and p.W2626C) to be deleterious and 2 (p.I2490T and p.K2729N) probably neutral. Such studies are important to understand the functional significance of unclassified BRCA2 variants. (Blood. 2011;118(9):2430-2442)