G9a/GLP-dependent histone H3K9me2 patterning during human hematopoietic stem cell lineage commitment
G9a/GLP-dependent histone H3K9me2 patterning during human hematopoietic stem cell lineage commitment
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DOI：
10.1101/gad.200329.112
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发表时间：
2012-11-15
影响因子：
10.5
通讯作者：
Paddison, Patrick J.
中科院分区：
文献类型：
--
作者：
Chen, Xiaoji;Skutt-Kakaria, Kyobi;Paddison, Patrick J.
G9 a和GLP是保守的蛋白质甲基转移酶，其在哺乳动物发育期间通过组蛋白H3 Lys 9（H3 K9 me 1/2）的单和二甲基化（与转录抑制相关的修饰）发挥关键作用。在胚胎发生过程中，出现了大的H3 K9 me 2染色质区域，已经提出通过影响高阶染色质结构来加强谱系选择。在这里，我们报告说，在成人造血干细胞和祖细胞（HSPCs），H3 K9 me 2染色质领土是不存在的原始细胞和从头形成的谱系承诺。在定向HSPC中，G9 a/GLP活性使基因区域内的CpG岛和其他基因组位点处的H3 K9 me 2标记成核，然后在分化期间扩散到大多数基因区域。免疫荧光测定揭示了H3 K9 me 2核斑点在定向HSPC中的出现，与进行性标记一致。此外，基因表达分析表明，G9 a/GLP活性抑制谱系相关基因和某些基因簇的混杂转录，提示HSPC染色质结构的调节。值得注意的是，用G9 a/GLP小分子抑制剂UNC 0638连续处理的HSPC在体外扩增期间更好地保留了干细胞样表型和功能。这些结果表明，G9 a/GLP活性在HSPC谱系特化期间促进进行性H3 K9 me 2模式化，并且其抑制延迟HSPC谱系定型。它们还为供体来源的HSPC的临床操作提供信息。
G9a and GLP are conserved protein methyltransferases that play key roles during mammalian development through mono-and dimethylation of histone H3 Lys 9 (H3K9me1/2), modifications associated with transcriptional repression. During embryogenesis, large H3K9me2 chromatin territories arise that have been proposed to reinforce lineage choice by affecting high-order chromatin structure. Here we report that in adult human hematopoietic stem and progenitor cells (HSPCs), H3K9me2 chromatin territories are absent in primitive cells and are formed de novo during lineage commitment. In committed HSPCs, G9a/GLP activity nucleates H3K9me2 marks at CpG islands and other genomic sites within genic regions, which then spread across most genic regions during differentiation. Immunofluorescence assays revealed the emergence of H3K9me2 nuclear speckles in committed HSPCs, consistent with progressive marking. Moreover, gene expression analysis indicated that G9a/GLP activity suppresses promiscuous transcription of lineage-affiliated genes and certain gene clusters, suggestive of regulation of HSPC chromatin structure. Remarkably, HSPCs continuously treated with UNC0638, a G9a/GLP small molecular inhibitor, better retain stem cell-like phenotypes and function during in vitro expansion. These results suggest that G9a/GLP activity promotes progressive H3K9me2 patterning during HSPC lineage specification and that its inhibition delays HSPC lineage commitment. They also inform clinical manipulation of donor-derived HSPCs.