Age and insertion site dependence of repeat number instability of a human DM1 transgene in individual mouse sperm.
Age and insertion site dependence of repeat number instability of a human DM1 transgene in individual mouse sperm.
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个体小鼠精子中人类 DM1 转基因重复次数不稳定性的年龄和插入位点依赖性。
DOI：
10.1093/hmg/11.7.791
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发表时间：
2002
影响因子：
3.5
通讯作者：
Meistrich,MarvinL
中科院分区：
文献类型：
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作者：
Zhang,Yun;Monckton,DarrenG;Siciliano,MichaelJ;Connor,ThomasH;Meistrich,MarvinL
精确测量生殖系重复数突变对于理解扩展三核苷酸重复疾病的分子病因是重要的。我们采用单基因组等效PCR技术检测了两个具有相同遗传背景的CTG·CAG扩增的Dmt转基因小鼠品系的精子DNA突变频率。单基因组等效PCR表明，在其他研究中从大量精子DNA的PCR中获得的明显突变谱主要是PCR口吃而不是突变的结果。我们发现，8周龄Dmt-D小鼠精子的突变频率（>1个重复的变化）（14.2%）显著高于同龄Dmt-E小鼠精子的突变频率（5.5%），与系谱分析一致。此外，Dmt-D小鼠精子中的突变频率随着年龄的增长而显著增加（17周龄时为28.0%）。扩增程度的年龄依赖性意味着生精干细胞中的突变随着时间的推移而积累。在人类每个精子发生周期中类似的扩增速率将产生在人类疾病如强直性肌营养不良1型中观察到的大扩增。系谱数据显示，女性传播中重复收缩的年龄依赖性偏差显着，男性传播中随着年龄的增长有扩大的趋势。因此，一个男性精子DNA的直接单基因组等效PCR似乎可以预测其后代可能遗传的突变等位基因大小的分布。与最近的一份报告形成进一步对比的是，后代的性别对突变长度变化的方向没有可检测到的影响。
Precise measurement of germline repeat number mutations is important for understanding the molecular etiology of expanded trinucleotide repeat diseases. We used single genome-equivalent PCR of sperm DNA to measure the mutation frequencies in two lines ofDmttransgenic mice containing an expanded CTG·CAG tract on an identical genetic background. Single genome-equivalent PCR indicated that apparent mutational spectra derived in other investigations from PCR of bulk sperm DNA were largely the consequence of PCR stutter and not mutations. Here we show that sperm from 8-week-oldDmt-D mice had a significantly higher mutation frequency (change of >1 repeat) (14.2%) than those ofDmt-E mice of the same age (5.5%), in agreement with pedigree analysis. Furthermore, the mutation frequency in sperm ofDmt-D mice increased significantly with age (28.0% at 17 weeks). The age dependence of the degree of expansion implies that mutations accumulate with time in spermatogenic stem cells. Similar rates of expansion per spermatogenic cycle in man would yield the large expansions observed in human diseases such as myotonic dystrophy type 1. Pedigree data showed a significant age-dependent bias toward repeat contraction in female transmissions and a trend towards expansion with age in male transmissions. Thus, direct single genome-equivalent PCR of the sperm DNA of an individual male appears to predict the distribution of mutant allele sizes that might be inherited by its offspring. In further contrast to a recent report, the sex of the offspring had no detectable effect on the direction of the mutational length change.