Human THAP7 is a chromatin-associated, histone tail-binding protein that represses transcription via recruitment of HDAC3 and nuclear hormone receptor corepressor
Human THAP7 is a chromatin-associated, histone tail-binding protein that represses transcription via recruitment of HDAC3 and nuclear hormone receptor corepressor
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DOI：
10.1074/jbc.m411675200
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发表时间：
2005-02-25
影响因子：
4.8
通讯作者：
Chakravarti, D
中科院分区：
文献类型：
--
作者：
Macfarlan, T;Kutney, S;Chakravarti, D
整合组蛋白低乙酰化和转录抑制的信号转导蛋白的身份很大程度上未知。在这里，我们证明 THAP7 是最近鉴定的 THAP（Thanatos 相关蛋白）蛋白家族的一个未表征的成员，它广泛表达，与染色质相关并抑制转录。 THAP7 在体外通过其 C 端 77 个氨基酸优先结合低乙酰化（非乙酰化、单乙酰化和二乙酰化）组蛋白 H4 尾部。删除该结构域或用组蛋白脱乙酰酶抑制剂 TSA 处理细胞会导致组蛋白过度乙酰化，从而部分破坏活细胞中的 THAP7/染色质关联。 THAP7 与组蛋白脱乙酰酶 3 (HDAC3) 和核激素受体辅阻遏物 (NCoR) 共免疫沉淀，并作为 Gal4 融合蛋白抑制转录。染色质免疫沉淀分析表明，这些辅阻遏物以 THAP7 依赖性方式被招募至启动子，并促进组蛋白 H3 低乙酰化。保守的 THAP 结构域是体外 HDAC3 完全关联的关键决定因素，THAP 结构域和组蛋白相互作用结构域对于 THAP7 的抑制特性都很重要。 THAP7 介导的完全抑制也依赖于 NCoR 表达。我们假设 THAP7 是一种双功能阻遏蛋白，它主动靶向组蛋白 H3 的脱乙酰化，这是建立转录抑制所必需的，并且充当低乙酰化组蛋白 H4 的抑制标记的信号转导器。这是人类 THAP 结构域蛋白的转录调控特性的首次证明，也是对高等真核生物中低乙酰化组蛋白 H4 抑制信号的潜在转导器的关键鉴定。
The identities of signal transducer proteins that integrate histone hypoacetylation and transcriptional repression are largely unknown. Here we demonstrate that THAP7, an uncharacterized member of the recently identified THAP (Thanatos-associated protein) family of proteins, is ubiquitously expressed, associates with chromatin, and represses transcription. THAP7 binds preferentially to hypoacetylated (un-, mono-, and di-acetylated) histone H4 tails in vitro via its C-terminal 77 amino acids. Deletion of this domain, or treatment of cells with the histone deacetylase inhibitor TSA, which leads to histone hyperacetylation, partially disrupts THAP7/chromatin association in living cells. THAP7 coimmunoprecipitates with histone deacetylase 3 (HDAC3) and the nuclear hormone receptor corepressor (NCoR) and represses transcription as a Gal4 fusion protein. Chromatin immunoprecipitation assays demonstrate that these corepressors are recruited to promoters in a THAP7 dependent manner and promote histone H3 hypoacetylation. The conserved THAP domain is a key determinant for full HDAC3 association in vitro, and both the THAP domain and the histone interaction domain are important for the repressive properties of THAP7. Full repression mediated by THAP7 is also dependent on NCoR expression. We hypothesize that THAP7 is a dual function repressor protein that actively targets deacetylation of histone H3 necessary to establish transcriptional repression and functions as a signal transducer of the repressive mark of hypoacetylated histone H4. This is the first demonstration of the transcriptional regulatory properties of a human THAP domain protein, and a critical identification of a potential transducer of the repressive signal of hypoacetylated histone H4 in higher eukaryotes.