LSH cooperates with DNA Methyltransferases to repress transcription
LSH cooperates with DNA Methyltransferases to repress transcription
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DOI：
10.1128/mcb.01073-07
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发表时间：
2008-01-01
影响因子：
5.3
通讯作者：
Stancheva, Irina
中科院分区：
文献类型：
--
作者：
Myant, Kevin;Stancheva, Irina
LSH是一种与SNF2家族染色质重塑ATP酶相关的蛋白质，是哺乳动物有效DNA甲基化所必需的。LSH如何支持DNA甲基化以及它是否与含有DNA甲基转移酶（DNMT）的大蛋白复合物相关目前尚不清楚。在这里，我们表明，与许多其他染色质重塑ATP酶，天然LSH主要是作为一个单体蛋白在哺乳动物细胞的核提取物，不能检测到一个大的多亚基复合物。然而，当靶向报告基因的启动子时，LSH充当有效的转录阻遏物。使用此作为鉴定LSH介导的抑制所需的蛋白质的测定，我们发现LSH与DNMT DNMT 1和DNMT 3B以及与组蛋白脱乙酰基酶（HDAC）HDAC 1和HDAC 2协作以沉默转录。我们发现，LSH的转录抑制和与HDAC的相互作用在DNMT 1和DNMT 3B敲除细胞中丢失，但DNMT的酶活性不需要LSH介导的沉默。我们的数据表明，LSH作为DNMT和HDAC的招募因子，以建立转录抑制性染色质，其可能通过靶位点的DNA甲基化进一步稳定。
LSH, a protein related to the SNF2 family of chromatin-remodeling ATPases, is required for efficient DNA methylation in mammals. How LSH functions to support DNA methylation and whether it associates with a large protein complex containing DNA methyltransferase (DNMT) enzymes is currently unclear. Here we show that, unlike many other chromatin-remodeling ATPases, native LSH is present mostly as a monomeric protein in nuclear extracts of mammalian cells and cannot be detected in a large multisubunit complex. However, when targeted to a promoter of a reporter gene, LSH acts as an efficient transcriptional repressor. Using this as an assay to identify proteins that are required for LSH-mediated repression we found that LSH cooperates with the DNMTs DNMT1 and DNMT3B and with the histone deacetylases (HDACs) HDAC1 and HDAC2 to silence transcription. We show that transcriptional repression by LSH and interactions with HDACs are lost in DNMT1 and DNMT3B knockout cells but that the enzymatic activities of DNMTs are not required for LSH-mediated silencing. Our data suggest that LSH serves as a recruiting factor for DNMTs and HDACs to establish transcriptionally repressive chromatin which is perhaps further stabilized by DNA methylation at targeted loci.