Evolution of variable lymphocyte receptor B antibody loci in jawless vertebrates
Evolution of variable lymphocyte receptor B antibody loci in jawless vertebrates
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DOI：
10.1073/pnas.2116522118
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发表时间：
2021-12-14
影响因子：
11.1
通讯作者：
Cooper，Max D.
中科院分区：
文献类型：
--
作者：
Das，Sabyasachi;Rast，Jonathan P.;Cooper，Max D.
VLRA、VLRB和VLRC三种类型的可变淋巴细胞受体基因编码现存的无颌脊椎动物、七鳃鳗和七鳃鳗中的抗原识别受体。这些VLR的体细胞多样性是通过将富含亮氨酸的重复序列(LRR)序列逐步复制到一个不完整的种系VLR基因中而产生的。表达VLRA或VLRC的淋巴细胞为T细胞样细胞，表达VLRB的细胞为B细胞样细胞。在这里，我们分析了不同无颌脊椎动物的VLRBs基因的组成，以阐明其结构和进化修饰。两种鳗鱼的不完全生殖系VLRB1基因含有较短的非编码插入序列，而6种典型七鳃鳗的生殖系VLRB3基因具有更长的插入序列，表现出显著的基因组变异。在日本七鳃鳗和七鳃鳗中发现了潜在的LRRcassette供体的基因组簇，其片段被复制以完成VLRB基因组装。在七鳃鳗中，428LRR盒分布在五个簇中，分布在总共1.7MbP的染色体DNA上。在我们的分析中，优先使用不同的供体盒进行VLRBs的组装，揭示了LampreyVLRB1基因的进化修饰，阐明了复杂的VLRb基因座的组织，并提供了海鳗和日本七鳃鳗中供体VLRB盒的全面目录。
Three types of variable lymphocyte receptor (VLR) genes,VLRA,VLRB, andVLRC,encode antigen recognition receptors in the extant jawless vertebrates, lampreys and hagfish. The somatically diversified repertoires of these VLRs are generated by serial stepwise copying of leucine-rich repeat (LRR) sequences into an incomplete germlineVLRgene. Lymphocytes that express VLRA or VLRC are T cell–like, while VLRB-expressing cells are B cell–like. Here, we analyze the composition of theVLRBlocus in different jawless vertebrates to elucidate its configuration and evolutionary modification. The incomplete germlineVLRBgenes of two hagfish species contain short noncoding intervening sequences, whereas germlineVLRBgenes in six representative lamprey species have much longer intervening sequences that exhibit notable genomic variation. Genomic clusters of potentialLRRcassette donors, fragments of which are copied to completeVLRBgene assembly, are identified in Japanese lamprey and sea lamprey. In the sea lamprey, 428LRRcassettes are located in five clusters spread over a total of 1.7 Mbp of chromosomal DNA. Preferential usage of the different donor cassettes forVLRBassemblage is characterized in our analysis, which reveals evolutionary modifications of the lampreyVLRBgenes, elucidates the organization of the complexVLRBlocus, and provides a comprehensive catalog of donorVLRBcassettes in sea lamprey and Japanese lamprey.