Loss of heterozygosity and mitotic linkage maps in the mouse.
Loss of heterozygosity and mitotic linkage maps in the mouse.
复制标题
小鼠杂合性和有丝分裂连锁图谱的丢失。
DOI：
10.1073/pnas.88.15.6486
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发表时间：
1991
影响因子：
11.1
通讯作者：
Carlson,GA
中科院分区：
文献类型：
--
作者：
Henson,V;Palmer,L;Banks,S;Nadeau,JH;Carlson,GA
杂合性缺失是一种重要的致癌机制，可涉及多种机制，包括染色体丢失、缺失和同源染色体间有丝分裂重组。对杂合子小鼠细胞系H-2抗原丢失变异体的分析提供了一个实验系统，以估计不同等位基因丢失机制的相对贡献，并比较有丝分裂和减数分裂重组的染色体模式。用细胞毒性抗H-2D抗体和补体从H-2d/H-2b杂合子细胞系中分离出161个独立的靶抗原阴性克隆，其中131个(84.5%)丢失了编码靶抗原的等位基因。通过限制性内切酶切点变异和Southern分析，对6个H-2D-近端17号染色体标记和1个远端标记的等位基因缺失变异进行分类并评分为杂合或纯合。一个有丝分裂交换可以解释50个克隆(37%)，至少有一个近端标记具有杂合性，而假定重组位点远端的所有标记都具有杂合性丢失。82个等位基因缺失变异体(60%)是所有标记的纯合子；这些克隆的起源可能是染色体丢失或着丝粒与最近端标记之间的有丝分裂重组。只有4个克隆(3%)是通过多次交叉或删除等更复杂的事件而产生的。构建了小鼠17号染色体有丝分裂连锁图谱，由体细胞重组得到的基因序列与传统传递遗传学获得的基因序列完全一致。这些结果表明，尽管缺乏同源染色体频繁体细胞配对的证据，有丝分裂重组是导致等位基因丢失的常见事件。有丝分裂图谱为有丝分裂和减数分裂重组的比较提供了一个明确的系统，并可能在阐明肿瘤发生的体细胞机制和通过同源重组将突变定向到特定位置的基因治疗方面取得实际进展。
Loss of heterozygosity is a significant oncogenetic mechanism and can involve a variety of mechanisms including chromosome loss, deletion, and homologous interchromosomal mitotic recombination. Analysis of H-2 antigen-loss variants from heterozygous murine cell lines provides an experimental system to estimate the relative contributions of different mechanisms for allele loss and to compare the chromosomal patterns of mitotic and meiotic recombination. Cytotoxic anti-H-2D antibodies and complement were used to isolate 161 independent target antigen-negative clones from H-2d/H-2b heterozygous cell lines; of these, 131 (84.5%) lost the allele encoding the target antigen. Allele-loss variants were typed and scored as either heterozygous or homozygous for six H-2D-proximal chromosome 17 markers and for one distal marker by restriction enzyme-site variations and Southern analysis. A single mitotic crossover could account for 50 clones (37%), with heterozygosity for at least one proximal marker and loss of heterozygosity for all markers distal to the putative recombination site. Eighty-two allele-loss variants (60%) were homozygous for all markers; the origin of these clones could be either chromosome loss or mitotic recombination between the centromere and the most proximal marker. Only 4 clones (3%) arose through more complex events such as multiple crossovers or deletion. A mitotic linkage map for mouse chromosome 17 was constructed, and the gene order deduced from somatic recombination was identical to that obtained by conventional transmission genetics. These results demonstrate that mitotic recombination is a common event leading to allele loss, in spite of the lack of evidence for frequent somatic pairing of homologous chromosomes. Mitotic mapping provides a defined system for comparison of mitotic and meiotic recombination and may lead to practical advances for elucidating somatic mechanisms of oncogenesis and for gene therapy in targeting mutations to specific sites through homologous recombination.