Targeted and extended acetylation of histones H4 and H3 at active and inactive genes in chicken embryo erythrocytes
Targeted and extended acetylation of histones H4 and H3 at active and inactive genes in chicken embryo erythrocytes
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DOI：
10.1074/jbc.m009472200
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发表时间：
2001-06-08
影响因子：
4.8
通讯作者：
Crane-Robinson, C
中科院分区：
文献类型：
--
作者：
Myers, FA;Evans, DR;Crane-Robinson, C
亲和纯化的多克隆抗体可识别组蛋白 H3 和 H4 的最高乙酰化形式，用于通过微球菌核酸酶消化从 15 天鸡胚红细胞中获得的染色质片段进行免疫沉淀测定。超乙酰化的 H4 和 H3 的分布被映射到管家基因甘油醛 S-磷酸脱氢酶 (GAPDH) 上，并且发现组织特异性基因碳酸酐酶 (CA)、H3 和 H4 乙酰化针对这两个基因 5' 端的 CpG 岛区域，并在下游方向脱落。相比之下，在 β (A)-珠蛋白基因中，H3 和 H4 在整个基因和下游增强子处都高度乙酰化，在启动子处乙酰化程度最高。在失活的卵清蛋白基因的 5' 端观察到低水平的乙酰化。测量正在进行的转录的连续测定表明，GAPDH 和 CA 基因的转录速率比成人 β (A)-珠蛋白基因低得多。 β (A)-珠蛋白基因广泛的高水平乙酰化与其高转录率最简单地相关。 GAPDH 和 CA 基因处组蛋白 H3 和 H4 的靶向乙酰化与转录起始中的作用一致，并且意味着转录延伸不一定需要过度乙酰化。
Affinity-purified polyclonal antibodies recognizing the most highly acetylated forms of histones H3 and H4 were used in immunoprecipitation assays with chromatin fragments derived from 15-day chicken embryo erythrocytes by micrococcal nuclease digestion. The distribution of hyperacetylated H4 and H3 was mapped at the housekeeping gene, glyceraldehyde S-phosphate dehydrogenase (GAPDH), and the tissue-specific gene, carbonic anhydrase (CA), H3 and H4 acetylation was found targeted to the CpG island region at the 5' end of both these genes, falling off in the downstream direction. In contrast, at the beta (A)-globin gene, both H3 and H4 are highly acetylated throughout the gene and at the downstream enhancer, with a maximum at the promoter. Low level acetylation was observed at the 5' end of the inactive ovalbumin gene. Run-on assays to measure ongoing transcription showed that the GAPDH and CA genes are transcribed at a much lower rate than the adult beta (A)-globin gene. The extensive high level acetylation at the beta (A)-globin gene correlates most simply with its high rate of transcription. The targeted acetylation of histones H3 and H4 at the GAPDH and CA genes is consistent with a role in transcriptional initiation and implies that transcriptional elongation does not necessarily require hyperacetylation.