Regulated recruitment of HP1 to a euchromatic gene induces mitotically heritable, epigenetic gene silencing: a mammalian cell culture model of gene variegation
Regulated recruitment of HP1 to a euchromatic gene induces mitotically heritable, epigenetic gene silencing: a mammalian cell culture model of gene variegation
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DOI：
10.1101/gad.1102803
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发表时间：
2003-08-01
影响因子：
10.5
通讯作者：
Rauscher, FJ
中科院分区：
文献类型：
--
作者：
Ayyanathan, K;Lechner, MS;Rauscher, FJ
异染色质蛋白1（Heterochromatin protein 1，HP 1）是果蝇异染色质的重要组成部分，是果蝇表观遗传基因沉默的重要组成部分。哺乳动物HP 1蛋白家族知之甚少，其可能是常染色质的，通过阻遏物-辅阻遏物复合物靶向表达的基因座，并通过Lys 9-甲基化组蛋白H3（H3-MeK 9）保留在那里。为了表征由HP 1结合的常染色质基因座的物理性质，我们开发了一种策略，通过使用合成的、酶调节的KRAB抑制结构域来调节HP 1向哺乳动物细胞中表达的转基因的募集。我们发现，它的专性辅阻遏物，KAP 1，可以协调稳定的基因沉默所需的所有机制。在激素的存在下，转基因被迅速沉默，空间募集到HP 1丰富的核区域，假设一个紧凑的染色质结构，并与KAP 1，HP 1，和H3赖氨酸9特异性甲基转移酶，SETDB 1，在一个高度本地化的区域集中在启动子。值得注意的是，在克隆细胞群体中不存在激素的情况下，通过短脉冲激素建立的沉默稳定地维持>50个群体倍增时间，并且这些克隆中的沉默转基因显示启动子超甲基化。因此，像果蝇中的杂色一样，哺乳动物HP 1到常染色质启动子的募集可以建立表观遗传可遗传的沉默状态。
Heterochromatin protein 1 (HP1) is a key component of constitutive heterochromatin in Drosophila and is required for stable epigenetic gene silencing classically observed as position effect variegation. Less is known of the family of mammalian HP1 proteins, which may be euchromatic, targeted to expressed loci by repressor-corepressor complexes, and retained there by Lys 9-methylated histone H3 (H3-MeK9). To characterize the physical properties of euchromatic loci bound by HP1, we developed a strategy for regulated recruitment of HP1 to an expressed transgene in mammalian cells by using a synthetic, hormone-regulated KRAB repression domain. We show that its obligate corepressor, KAP1, can coordinate all the machinery required for stable gene silencing. In the presence of hormone, the transgene is rapidly silenced, spatially recruited to HP1-rich nuclear regions, assumes a compact chromatin structure, and is physically associated with KAP1, HP1, and the H3 Lys 9-specific methyltransferase, SETDB1, over a highly localized region centered around the promoter. Remarkably, silencing established by a short pulse of hormone is stably maintained for >50 population doublings in the absence of hormone in clonal-cell populations, and the silent transgenes in these clones show promoter hypermethylation. Thus, like variegation in Drosophila, recruitment of mammalian HP1 to a euchromatic promoter can establish a silenced state that is epigenetically heritable.