Accumulation of mutations and somatic selection in aging neural stem/progenitor cells
Accumulation of mutations and somatic selection in aging neural stem/progenitor cells
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DOI：
10.1111/j.1474-9728.2004.00128.x
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发表时间：
2004-12-01
期刊：
影响因子：
7.8
通讯作者：
Pruitt, SC
中科院分区：
文献类型：
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作者：
Bailey, KJ;Maslov, AY;Pruitt, SC
体干细胞内的基因组不稳定性可能导致突变的积累，并导致癌症或其他与年龄相关的表型。然而，从整个组织样本中确定个体干细胞之间不同的突变频率是困难的，因为每个事件在干细胞和分化组织的总群体中被稀释。在这里，克隆扩增神经干/祖细胞的能力允许测量来自单个初始细胞的基因组改变。使用C57 B1/6 x DBA/2杂交小鼠，并使用菌株特异性引物进行PCR分析，以检测每个神经球的9条不同染色体上的杂合性缺失。比较了来自2个月和2岁小鼠的神经球发生变化的频率。在15个神经球来自年轻的动物父母的染色体都存在所有9对染色体。相比之下，16/17的老年动物的神经球表现出一个或多个染色体上的杂合性丢失（洛），7个表现出至少一个染色体区域的完全缺失。对于9号和19号染色体，在丢失的等位基因中存在显著的偏差，其中在每种情况下，C57 B1/6等位基因保留在6/6个表现出洛的神经球中。这些数据表明，老化导致神经干细胞隔室内的大量突变负荷，这可以预期会影响这些细胞的正常功能。此外，染色体9和19的特定等位基因的保留表明突变事件的子集导致神经干细胞隔室内的等位基因特异性存活优势。
Genomic instability within somatic stem cells may lead to the accumulation of mutations and contribute to cancer or other age-related phenotypes. However, determining the frequency of mutations that differ among individual stem cells is difficult from whole tissue samples because each event is diluted in the total population of both stem cells and differentiated tissue. Here the ability to expand neural stem/progenitor cells clonally permitted measurement of genomic alterations derived from a single initial cell. C57Bl/6 x DBA/2 hybrid mice were used and PCR analysis with strain-specific primers was performed to detect loss of heterozygosity on nine different chromosomes for each neurosphere. The frequency with which changes occurred in neurospheres derived from 2-month- and 2-year-old mice was compared. In 15 neurospheres derived from young animals both parental chromosomes were present for all nine chromosome pairs. In contrast, 16/17 neurospheres from old animals demonstrated loss of heterozygosity (LOH) on one or more chromosomes and seven exhibited a complete deletion of at least one chromosomal region. For chromosomes 9 and 19 there is a significant bias in the allele that is lost where in each case the C57Bl/6 allele is retained in 6/6 neurospheres exhibiting LOH. These data suggest that aging leads to a substantial mutational load within the neural stem cell compartment which can be expected to affect the normal function of these cells. Furthermore, the retention of specific alleles for chromosomes 9 and 19 suggests that a subset of mutational events lead to an allele-specific survival advantage within the neural stem cell compartment.