期刊名称：Proceedings of the National Academy of Sciences
印刷版ISSN：0027-8424
电子版ISSN：1091-6490
出版年度：2019
卷号：116
期号：49
页码：24779-24785
DOI：10.1073/pnas.1914163116
出版社：The National Academy of Sciences of the United States of America
摘要：The super-enhancers (SEs) of lineage-specific genes in B cells are off-target sites of somatic hypermutation. However, the inability to detect sufficient numbers of mutations in normal human B cells has precluded the generation of a high-resolution mutational landscape of SEs. Here we captured and sequenced 12 B cell SEs at single-nucleotide resolution from 10 healthy individuals across diverse ethnicities. We detected a total of approximately 9,000 subclonal mutations (allele frequencies T/G > A and A > G/T > C substitutions, consistent with the activities of activation-induced-cytidine deaminase (AID) and the A-T mutator, DNA polymerase η, respectively, in mutagenesis in normal B cells. Analyses of mutational signatures further corroborate the participation of these factors in this process. Single base substitution signatures SBS85, SBS37, and SBS39 were found in the BCL6 SE. While SBS85 is a denoted signature of AID in lymphoid cells, the etiologies of SBS37 and SBS39 are unknown. Our analysis suggests the contribution of error-prone DNA polymerases to the latter signatures. The high-resolution mutation landscape has enabled accurate profiling of subclonal mutations in B cell SEs in normal individuals. By virtue of the fact that subclonal SE mutations are clonally expanded in B cell lymphomas, our studies also offer the potential for early detection of neoplastic alterations..
