我们机体细胞中的遗传物质包括活跃和非活跃区域，当活跃区域的基因被阅读以后，非活跃的区域依然保持着封锁状态。基因组中这些功能性的保守性、紧密的区域对于基因调节以及细胞分裂期间染色体的稳定性和正确分散至关重要。这些结构区域可以被遗传物质或者组蛋白类进行生化特异性地修饰。在果蝇中识别出的异染色质蛋白质1（HP1）可以特异性地结合修饰过高特异性的组蛋白，并且保证关闭区域的失活。
HP1可以监视遗传物质的失活
HP1可以特异性地集合被标记的组蛋白并且关闭其基因组序列，使用一种酵母生物学及生物物理学的结合技术，研究者从分子水平揭示了这个过程。HP1可以拦截受抑制的遗传物质的RNA转录，并且护送这些分子至细胞机器中，然后降解它们。同时，一种新的HP1可以占据组蛋白中腾出的空间。这种连续性的逆转保证了来自失活区域的RNA转录是持续被破坏的。
动态交互作用
生物物理学的方法揭示了HP1可以动态操控染色质的状态。这种动力循环允许细胞在同一时间、不同水平上来控制基因的钝化。研究者的发现阐述了在酵母中HP1的重要性。然而，HP1一直在进化之中，而且目前只存在于人类细胞中，未来演技组合希望通过揭示其在男性中所扮演的角色，并且进一步研究HP1的结构。相关研究成果刊登在了近日的国际杂志Molecular Cell上。（生物谷Bioon.com）
编译自：Molecular controller switches off genetic material
编译者：T.Shen
doi:10.1016/j.molcel.2012.05.009
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HP1Swi6 Mediates the Recognition and Destruction of Heterochromatic RNA Transcripts
Claudia Keller1, 2, Ricardo Adaixo3, Rieka Stunnenberg1, 2, Katrina J. Woolcock1, 2, Sebastian Hiller3, , , Marc Bühler1, 2, ,
HP1 proteins are major components of heterochromatin, which is generally perceived to be an inert and transcriptionally inactive chromatin structure. Yet, HP1 binding to chromatin is highly dynamic and robust silencing of heterochromatic genes can involve RNA processing. Here, we demonstrate by a combination of in vivo and in vitro experiments that the fission yeast HP1Swi6 protein guarantees tight repression of heterochromatic genes through RNA sequestration and degradation. Stimulated by positively charged residues in the hinge region, RNA competes with methylated histone H3K9 for binding to the chromodomain of HP1Swi6. Hence, HP1Swi6 binding to RNA is incompatible with stable heterochromatin association. We propose a model in which an ensemble of HP1Swi6 proteins functions as a heterochromatin-specific checkpoint, capturing and priming heterochromatic RNAs for the RNA degradation machinery. Sustaining a functional checkpoint requires continuous exchange of HP1Swi6 within heterochromatin, which explains the dynamic localization of HP1 proteins on heterochromatin.
