Neurospora chromosomes are organized by blocks of importin alpha-dependent heterochromatin that are largely independent of H3K9me3.
Neurospora chromosomes are organized by blocks of importin alpha-dependent heterochromatin that are largely independent of H3K9me3.
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DOI：
10.1101/gr.203182.115
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发表时间：
2016-08
期刊：
影响因子：
7
通讯作者：
Freitag M
中科院分区：
文献类型：
--
作者：
Galazka JM;Klocko AD;Uesaka M;Honda S;Selker EU;Freitag M
真核基因组被组织成具有三维排列的染色质结构域，这可能是由染色质成分（蛋白质、DNA 和 RNA）在细胞核的物理限制内相互作用产生的。我们使用染色体构象捕获 (3C)，然后对粗糙脉孢菌野生型和突变株进行高通量测序 (Hi-C)，以深入了解异染色质在基因组组织和功能中的作用。我们测试了三种被认为对异染色质建立很重要的蛋白质的作用，即组蛋白 H3 赖氨酸 9 甲基转移酶 DIM-5、异染色质蛋白 1 (HP1)（特异性结合 DIM-5 的产物（三甲基化 H3 赖氨酸 9 [H3K9me3]））和 DIM-3（导入蛋白 α）（参与 DIM-5 定位）。野生型菌株的平均基因组配置揭示了组成型和兼性异染色质结构域之间强烈的染色体内和染色体间关联，着丝粒、亚端粒和散布的异染色质之间的相互作用最强。令人惊讶的是，H3K9me3 或 HP1 的缺失对异染色质压缩仅产生轻微影响，而 dim-3 则引起更剧烈的变化，特别是减少组成型异染色质结构域之间的相互作用。因此，异染色质区域之间的关联是脉孢菌染色体构象的主要组成部分，但两个广泛研究的关键异染色质蛋白并不是必需的，这意味着未定义的蛋白质因子在维持整体染色体组织中发挥着关键作用。
Eukaryotic genomes are organized into chromatin domains with three-dimensional arrangements that presumably result from interactions between the chromatin constituents—proteins, DNA, and RNA—within the physical constraints of the nucleus. We used chromosome conformation capture (3C) followed by high-throughput sequencing (Hi-C) with wild-type and mutant strains of Neurospora crassa to gain insight into the role of heterochromatin in the organization and function of the genome. We tested the role of three proteins thought to be important for establishment of heterochromatin, namely, the histone H3 lysine 9 methyltransferase DIM-5, Heterochromatin Protein 1 (HP1), which specifically binds to the product of DIM-5 (trimethylated H3 lysine 9 [H3K9me3]), and DIM-3 (importin alpha), which is involved in DIM-5 localization. The average genome configuration of the wild-type strain revealed strong intra- and inter-chromosomal associations between both constitutive and facultative heterochromatic domains, with the strongest interactions among the centromeres, subtelomeres, and interspersed heterochromatin. Surprisingly, loss of either H3K9me3 or HP1 had only mild effects on heterochromatin compaction, whereas dim-3 caused more drastic changes, specifically decreasing interactions between constitutive heterochromatic domains. Thus, associations between heterochromatic regions are a major component of the chromosome conformation in Neurospora, but two widely studied key heterochromatin proteins are not necessary, implying that undefined protein factors play key roles in maintaining overall chromosome organization.