近日，中科院上海生命科学研究院/上海交通大学医学院健康科学研究所孔祥银课题组张振国等人发现基因重复后基因剪接信号演化特点，以及这些变化对基因新结构形成的影响，该成果在线发表在《基因生物学》(Genome Biology)杂志上。
在物种进化过程中，基因重复是经常发生的。那么基因重复后，基因结构是如何演化的？张振国等人发现基因重复后，早期阶段外显子剪接增强子（Exon splicing enhancers）和外显子剪接沉默子（Exon splicing silencers）快速变化，然后逐渐饱和。基因重复后，外显子剪接增强子严重丢失，这些改变主要与同义突变相关；剪接信号的改变同时导致基因新的剪接形式的发生。这一发现有助于理解新基因结构是如何演化的。（生物谷Bioon.com）
基因组进化研究：
GBE：哺乳动物基因组随进化加速变小
Nature Gene：细菌基因组正在快速进化
Genome Research：胎盘基因进化造就物种特异性
Nature：新性染色体进化驱动脊椎动物新种形成
生物谷推荐原始出处：
Genome Biology 2009, 10:R120doi:10.1186/gb-2009-10-11-r120
Divergence of exonic splicing elements after gene duplication and the impact on gene structures
Zhenguo Zhang , Li Zhou , Ping Wang , Yang Liu , Xianfeng Chen , Landian Hu and Xiangyin Kong
Background
The origin of new genes and their contribution to functional novelty has been the subject of considerable interest. There has been much progress in understanding the mechanisms by which new genes originate. Here we examine a novel way that new gene structures could originate, namely through the evolution of new alternative splicing isoforms after gene duplication.
Results
We studied the divergence of exonic splicing enhancers and silencers after gene duplication and the contributions of such divergence to the generation of new splicing isoforms. We found that exonic splicing enhancers and exonic splicing silencers diverge especially fast shortly after gene duplication. About 10% and 5% of paralogous exons undergo significantly asymmetric evolution of exonic splicing enhancers and silencers, respectively. When compared to pre-duplication ancestors, we found that there is a significant overall loss of exonic splicing enhancers and the magnitude increases with the duplication age. Detailed examination reveals net gains and losses of exonic splicing enhancers and silencers in different copies and paralog clusters after gene duplication. Furthermore, we found that exonic splicing enhancer and silencer changes are mainly caused by synonymous mutations, though nonsynonymous changes also contribute. Finally, we found that exonic splicing enhancer and silencer divergence results in exon splicing state transitions (from constitutive to alternative or vice versa), and that the proportion of paralogous exon pairs with different splicing states also increases over time, consistent with previous predictions.
Conclusions
Our results suggest that exonic splicing enhancer and silencer changes after gene duplication have important roles in alternative splicing divergence and that these changes contribute to the generation of new gene structures.
