The evolution of sex chromosome dosage compensation in animals
The evolution of sex chromosome dosage compensation in animals
复制标题
动物性染色体剂量补偿的演变
DOI：
10.1016/j.jgg.2020.10.005
复制
发表时间：
2020-11-20
影响因子：
5.9
通讯作者：
Chen, Xiaoshu
中科院分区：
文献类型：
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作者：
Chen, Jiabi;Wang, Menghan;Chen, Xiaoshu
异形性染色体的进化将导致基因表达剂量的问题，因为至少在一种性别中，性连锁基因的剂量已经减少了一半。有人提出，在异配子性别中，整个X或Z染色体的转录输出应加倍以实现完全剂量补偿。然而，由于现有的方法来确定性染色体和常染色体之间的转录差异（S：A比）在不同的研究中的变化，我们收集了500多个公共RNA-Seq数据集，从多个组织和物种的主要分支，并提出了一个统一的计算框架，用于无偏和可比的测量多个物种的S：A比。我们还测试了剂量补偿的演变更直接地通过评估当前的性连锁基因相对于祖先的性连锁基因的表达水平的变化。我们发现，在哺乳动物和鸟类中，S：A比率约为0.5，而在昆虫，鱼类和扁形虫中，S：A比率约为1.0。进一步的分析表明，剂量敏感的管家基因在X/Z染色体上的分数与S：A比显着相关。此外，Y染色体的变性程度可能是哺乳动物中S：A比率变化的原因，而没有剂量补偿机制。我们的观察提供明确的支持动物的性染色体不敏感性假说，并建议性染色体的剂量敏感性状态是一个主要因素，不同的进化策略的剂量补偿。版权所有（C）2020，作者。中国科学院遗传与发育生物学研究所、中国遗传学会。由Elsevier Limited和Science Press出版。
The evolution of heteromorphic sex chromosomes shall lead to gene expression dosage problems, as in at least one of the sexes, the sex-linked gene dose has been reduced by half. It has been proposed that the transcriptional output of the whole X or Z chromosome should be doubled for complete dosage compensation in heterogametic sex. However, owing to the variability of the existing methods to determine the transcriptional differences between sex chromosomes and autosomes (S:A ratios) in different studies, we collected more than 500 public RNA-Seq data set from multiple tissues and species in major clades and proposed a unified computational framework for unbiased and comparable measurement of the S:A ratios of multiple species. We also tested the evolution of dosage compensation more directly by assessing changes in the expression levels of the current sex-linked genes relative to those of the ancestral sex-linked genes. We found that in mammals and birds, the S:A ratio is approximately 0.5, whereas in insects, fishes, and flatworms, the S:A ratio is approximately 1.0. Further analysis showed that the fraction of dosage-sensitive housekeeping genes on the X/Z chromosome is significantly correlated with the S:A ratio. In addition, the degree of degeneration of the Y chromosome may be responsible for the change in the S:A ratio in mammals without a dosage compensation mechanism. Our observations offer unequivocal support for the sex chromosome insensitivity hypothesis in animals and suggest that dosage sensitivity states of sex chromosomes are a major factor underlying different evolutionary strategies of dosage compensation. Copyright (C) 2020, The Authors. Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, and Genetics Society of China. Published by Elsevier Limited and Science Press.