Abi Rached L, McDermott M F, Pontarotti P
Institut de Cancérologie et d'Immunologie de Marseille, INSERM U119, France.
Immunol Rev. 1999 Feb;167:33-44. doi: 10.1111/j.1600-065x.1999.tb01380.x.
The human Major Histocompatibility Complex (MHC) shares similarities with three other chromosome regions in human. This could be the vestige of ancestral large scale duplications. We discuss here the possibility i) that these duplications occurred during two rounds of tetraploidization supposed to have taken place during chordate evolution before the jawed vertebrate radiation, and ii) that one of the quadruplicate regions, relaxed of functional constraints, gave rise to the vertebrate MHC by a quick round of gene cis-duplication and cis-exon shuffling. These different rounds of cis-duplications and exon shufflings allowed the emergence of new genes participating in novel biological functions i.e. adaptive immune responses. Cis-duplications and cis-exon shufflings are ongoing processes in the evolution of some of these genes in this region as they have occurred and were fixed at different times and in different lineages during vertebrate evolution. In contrast, other genes within the MHC have remained stable since the emergence of jawed vertebrates.
人类主要组织相容性复合体（MHC）与人类其他三个染色体区域存在相似性。这可能是祖先大规模基因复制的遗迹。我们在此讨论以下可能性：i）这些复制发生在两轮四倍体化过程中，这两轮四倍体化被认为发生在有颌脊椎动物辐射之前的脊索动物进化过程中；ii）四个重复区域之一，由于功能限制的放松，通过一轮快速的基因顺式复制和顺式外显子改组产生了脊椎动物的MHC。这些不同轮次的顺式复制和外显子改组使得参与新生物学功能（即适应性免疫反应）的新基因得以出现。顺式复制和顺式外显子改组在该区域某些基因的进化过程中仍在持续进行，因为它们在脊椎动物进化过程中于不同时间和不同谱系中发生并固定下来。相比之下，自颌口类脊椎动物出现以来，MHC内的其他基因一直保持稳定。
