Qiu Yanbo, Jiang Junyi, Yi Xiaohua, Wang Shuhui, Sun Xiuzhu
College of Grassland Agriculture, Northwest A&F University, Yangling, China.
College of Animal Science and Technology, Northwest A&F University, Yangling, China.
Dev Comp Immunol. 2025 May;166:105360. doi: 10.1016/j.dci.2025.105360. Epub 2025 Mar 18.
This study investigated the immunoglobulins (IG) gene locus structure and expression diversity in local Chinese horse and donkey breeds, including Ningqiang, Guanzhong horses, and varieties such as Guanzhong, Jiami, and Northern Shaanxi donkey using genome alignment and high-throughput sequencing. The aim was to expand understanding of IG expression patterns in horses, donkeys, and their different breeds. The results revealed that the donkey IGH locus contains 117 VH genes (23 functional), 44 DH genes, and 8 JH genes, arranged in a VH-DH-JH sequence on chromosome 7, spanning approximately 1189 kb. Both horses and donkeys exhibited high frequencies of the IGHV4-IGHD2-IGHJ6, IGHV4-IGHD4-IGHJ6, and IGHV4-IGHD2-IGHJ4 combinations during VDJ recombination. Significant differences in V, D, and J junctions between horses and donkeys, as well as among breeds, were observed, mainly due to variations in N-nucleotide insertion length. The CDR3H region in horses exhibited greater length diversity and a higher Cys content than that in donkeys, which may contribute to species-specific differences in IGH spatial structure. Both horses and donkeys showed a clear preference for A > G and G > A mutations during somatic hypermutation (SHM), with consistent trends across breeds and species. In conclusion, this study reveals that V(D)J recombination, junction diversity, and SHM are key mechanisms driving IGH diversity in horses and donkeys. While the basic mechanisms for IGH diversification are similar across species and breeds, their specific manifestations exhibit both distinct and consistent patterns, reflecting differences in immune system adaptations and providing a theoretical basis for understanding IGH expression diversity in equids.
本研究利用基因组比对和高通量测序技术，对中国地方马和驴品种（包括宁强马、关中马以及关中驴、佳米驴和陕北驴等品种）的免疫球蛋白（IG）基因座结构和表达多样性进行了研究。目的是扩大对马、驴及其不同品种中IG表达模式的了解。结果显示，驴的IGH基因座包含117个VH基因（23个功能性基因）、44个DH基因和8个JH基因，在7号染色体上以VH-DH-JH序列排列，跨度约为1189 kb。在VDJ重排过程中，马和驴的IGHV4-IGHD2-IGHJ6、IGHV4-IGHD4-IGHJ6和IGHV4-IGHD2-IGHJ4组合频率均较高。观察到马和驴之间以及不同品种之间在V、D和J连接上存在显著差异，主要是由于N-核苷酸插入长度的变化。马的CDR3H区域比驴表现出更大的长度多样性和更高的半胱氨酸含量，这可能导致IGH空间结构上的物种特异性差异。在体细胞超突变（SHM）过程中，马和驴对A>G和G>A突变均表现出明显偏好，且品种和物种间趋势一致。总之，本研究表明V(D)J重排、连接多样性和SHM是驱动马和驴IGH多样性的关键机制。虽然IGH多样化的基本机制在物种和品种间相似，但其具体表现既有明显差异又有一致模式，反映了免疫系统适应性的差异，为理解马科动物IGH表达多样性提供了理论依据。
