Lau Alyssa C, Csankovszki Györgyi
Department of Molecular, Cellular, and Developmental Biology, University of Michigan, USA.
Department of Molecular, Cellular, and Developmental Biology, University of Michigan, USA.
Curr Opin Genet Dev. 2015 Apr;31:50-6. doi: 10.1016/j.gde.2015.04.001. Epub 2015 May 16.
In Caenorhabditis elegans, males have one X chromosome and hermaphrodites have two. Emerging evidence indicates that the male X is transcriptionally more active than autosomes to balance the single X to two sets of autosomes. Because upregulation is not limited to males, hermaphrodites need to strike back and downregulate expression from the two X chromosomes to balance gene expression in their genome. Hermaphrodite-specific downregulation involves binding of the dosage compensation complex to both Xs. Advances in recent years revealed that the action of the dosage compensation complex results in compaction of the X chromosomes, changes in the distribution of histone modifications, and ultimately limiting RNA Polymerase II loading to achieve chromosome-wide gene repression.
在秀丽隐杆线虫中，雄性有一条X染色体，雌雄同体有两条。新出现的证据表明，雄性的X染色体在转录上比常染色体更活跃，以平衡单条X染色体与两套常染色体。由于上调并不局限于雄性，雌雄同体需要反击并下调两条X染色体的表达，以平衡其基因组中的基因表达。雌雄同体特异性下调涉及剂量补偿复合体与两条X染色体的结合。近年来的进展表明，剂量补偿复合体的作用导致X染色体压缩、组蛋白修饰分布改变，并最终限制RNA聚合酶II的装载，以实现全染色体范围的基因抑制。
