The chromatin-binding protein HMGN3 stimulates histone acetylation and transcription across the Glyt1 gene.
The chromatin-binding protein HMGN3 stimulates histone acetylation and transcription across the Glyt1 gene.
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DOI：
10.1042/bj20111502
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发表时间：
2012-03-15
期刊：
影响因子：
--
通讯作者：
West KL
中科院分区：
文献类型：
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作者：
Barkess G;Postnikov Y;Campos CD;Mishra S;Mohan G;Verma S;Bustin M;West KL
HMGN是核小体结合蛋白，其改变组蛋白修饰的模式并调节连接体组蛋白与染色质的结合。HMGN 3家族成员以两种剪接形式存在，全长的HMGN 3a和缺乏C末端RD（调节结构域）的HMGN 3b。在本研究中，我们使用Glyt 1（甘氨酸转运蛋白1）基因作为模型系统来研究HMGN蛋白在体内的位点之间的结合，并研究两个HMGN 3剪接变体如何影响组蛋白修饰和基因表达。我们证明，HMGN 1，HMGN 2，HMGN 3a和HMGN 3b的Glyt 1基因位点和周围区域的结合，并没有更高的启动子或推定的增强子富集。我们的结论是，H3 K4 me 3（组蛋白H3的三甲基化赖氨酸4）和H3 K9 ac（组蛋白H3的乙酰化赖氨酸9）在活性Glyt 1a启动子的峰不起主要作用，在招募HMGN蛋白。HMGN 3a/B结合导致H3 K14（组蛋白H3的Lys 14）乙酰化增加，并刺激Glyt 1a表达，但不改变H3 K4 me 3或H3 K9 ac富集水平。乙酰化试验表明，HMGN 3a刺激PCAF [p300/CREB（cAMP反应元件结合蛋白）结合蛋白相关因子]在体外乙酰化核小体H3的能力，而HMGN 3b没有。我们提出了一个模型，其中HMGN 3a/b刺激的H3 K14乙酰化跨越大基因如Glyt 1的身体可以导致更有效的转录延伸和增加mRNA的产生。
HMGNs are nucleosome-binding proteins that alter the pattern of histone modifications and modulate the binding of linker histones to chromatin. The HMGN3 family member exists as two splice forms, HMGN3a which is full-length and HMGN3b which lacks the C-terminal RD (regulatory domain). In the present study, we have used the Glyt1 (glycine transporter 1) gene as a model system to investigate where HMGN proteins are bound across the locus in vivo, and to study how the two HMGN3 splice variants affect histone modifications and gene expression. We demonstrate that HMGN1, HMGN2, HMGN3a and HMGN3b are bound across the Glyt1 gene locus and surrounding regions, and are not enriched more highly at the promoter or putative enhancer. We conclude that the peaks of H3K4me3 (trimethylated Lys4 of histone H3) and H3K9ac (acetylated Lys9 of histone H3) at the active Glyt1a promoter do not play a major role in recruiting HMGN proteins. HMGN3a/b binding leads to increased H3K14 (Lys14 of histone H3) acetylation and stimulates Glyt1a expression, but does not alter the levels of H3K4me3 or H3K9ac enrichment. Acetylation assays show that HMGN3a stimulates the ability of PCAF [p300/CREB (cAMP-response-element-binding protein)-binding protein-associated factor] to acetylate nucleosomal H3 in vitro, whereas HMGN3b does not. We propose a model where HMGN3a/b-stimulated H3K14 acetylation across the bodies of large genes such as Glyt1 can lead to more efficient transcription elongation and increased mRNA production.