A transcriptional coregulator, SPIN.DOC, attenuates the coactivator activity of Spindlin1
A transcriptional coregulator, SPIN.DOC, attenuates the coactivator activity of Spindlin1
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DOI：
10.1074/jbc.m117.814913
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发表时间：
2017-12-22
影响因子：
4.8
通讯作者：
Bedford, Mark T.
中科院分区：
文献类型：
--
作者：
Bae, Narkhyun;Gao, Min;Bedford, Mark T.
Spindlin1 （SPIN1）是一种转录辅激活因子，在胚胎发育和癌症中发挥重要作用。SPIN1包含三个都铎结构域，其中两个通过读取H3- lys -4三甲基化和H3- arg -8不对称二甲基化标记与组蛋白H3尾部相连。为了深入了解SPIN1作为转录辅激活子的作用机制，我们纯化了其相互作用蛋白。我们发现了一个未被鉴定的蛋白（C11orf84），我们将其重新命名为SPIN1对接蛋白（SPIN.DOC），该蛋白直接结合SPIN1并强烈破坏其组蛋白甲基化读取能力，导致其与染色质分离。Spindlin共激活子家族有5个相关成员（SPIN1、2A、2B、3和4），我们发现它们都能结合SPIN.DOC。此前有报道称，SPIN1通过直接与转录因子4 （transcription factor 4, TCF4）相互作用调控Wnt信号通路中的基因表达。我们在这里观察到，在TOPflash报告子实验中，SPIN1 . doc以依赖SPIN1的方式与TCF4结合，并抑制SPIN1共激活子的活性。此外，敲低和过表达实验表明，spin1 . doc抑制了许多spin1调控基因的表达，包括编码核糖体RNA和细胞因子IL1B的基因。总之，我们已经确定了SPIN.DOC是一种结合SPIN1的转录抑制因子，并掩盖了其参与H3-Lys-4三甲基化激活标记的能力。
Spindlin1 (SPIN1) is a transcriptional coactivator with critical functions in embryonic development and emerging roles in cancer. SPIN1 harbors three Tudor domains, two of which engage the tail of histone H3 by reading the H3-Lys-4 trimethylation and H3-Arg-8 asymmetric dimethylation marks. To gain mechanistic insight into how SPIN1 functions as a transcriptional coactivator, here we purified its interacting proteins. We identified an uncharacterized protein (C11orf84), which we renamed SPIN1 docking protein (SPIN.DOC), that directly binds SPIN1 and strongly disrupts its histone methylation reading ability, causing it to disassociate from chromatin. The Spindlin family of coactivators has five related members (SPIN1, 2A, 2B, 3, and 4), and we found that all of them bind SPIN.DOC. It has been reported previously that SPIN1 regulates gene expression in the Wnt signaling pathway by directly interacting with transcription factor 4 (TCF4). Weobserved here that SPIN.DOC associates with TCF4 in a SPIN1-dependent manner and dampens SPIN1 coactivator activity in TOPflash reporter assays. Furthermore, knockdown and overexpression experiments indicated that SPIN.DOC represses the expression of a number of SPIN1-regulated genes, including those encoding ribosomal RNA and the cytokine IL1B. In conclusion, we have identified SPIN.DOC as a transcriptional repressor that binds SPIN1 and masks its ability to engage the H3-Lys-4 trimethylation activation mark.