Reduced switching in SCID B cells is associated with altered somatic mutation of recombined S regions
Reduced switching in SCID B cells is associated with altered somatic mutation of recombined S regions
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DOI：
10.4049/jimmunol.171.12.6556
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发表时间：
2003-12-15
影响因子：
4.4
通讯作者：
Jolly, CJ
中科院分区：
文献类型：
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作者：
Cook, AJL;Oganesian, L;Jolly, CJ
脱氧核糖核酸双链断裂作为igv (D)J重组的中间产物，可能在IgH C基因之间的类开关重组中起着类似的作用。在slide小鼠中，由于dna依赖性蛋白激酶催化亚基（DNA-PKcs）蛋白缺陷，V(D)J重组被阻断。我们在这项研究中表明，当将SCID突变引入抗鸡蛋溶菌酶转基因B细胞时，可以检测到所有检测的同型转换，但与缺乏RAG1基因的具有相同特异性的对照B细胞相比，转换显着减少。因此，DNA-PKcs参与转换到所有同型，但在转换过程中的作用小于它在V(D) j编码接头形成中的作用。我们在SCID B细胞中观察到的开关水平高于其他人在DNA-PKcs（null）细胞中观察到的开关水平，这提出了激酶缺陷DNA-PKcs在开关中起作用的可能性。与对照RAG1(-/-) B细胞相比，SCID细胞重组开关区G:C碱基对与胞苷的点突变显著减少。SCID细胞中杂化S区意义链胞苷突变的优先丢失表明，在激活的B细胞的S区模板链上可能独立于激活诱导的胞苷脱氨酶形成缺口，并在激活诱导的胞苷脱氨酶对非模板链进行脱氨时转化为双链断裂。
Deoxyribonucleic acid double-stranded breaks act as intermediates in Ig V(D)J recombination and probably perform a similar function in class switch recombination between IgH C genes. In SLID mice, V(D)J recombination is blocked because the DNA-dependent protein kinase catalytic subunit (DNA-PKcs) protein is defective. We show in this study that switching to all isotypes examined was detectable when the SCID mutation was introduced into anti-hen egg lysozyme transgenic B cells capable of undergoing class switch recombination, but switching was significantly reduced in comparison with control B cells of the same specificity lacking the RAG1 gene. Thus, DNA-PKcs is involved in switching to all isotypes, but plays a lesser role in the switching process than it does in V(D)J-coding joint formation. The higher level of switching observed by us in SCID B cells compared with that observed by others in DNA-PKcs(null) cells raises the possibility that kinase-deficient DNA-PKcs can function in switching. Point mutation of G:C base pairs with cytidines on the sense strand was greatly reduced in recombined switch regions from SCID cells compared with control RAG1(-/-) B cells. The preferential loss of sense strand cytidine mutations from hybrid S regions in SCID cells suggests the possibility that nicks might form in S regions of activated B cells on the template strand independently of activation-induced cytidine deaminase and are converted to double-strand breaks when activation-induced cytidine deaminase deaminates the non-template strand.