Hollstein Ronja, Reiz Benedikt, Kötter Lucas, Richter Alev, Schaake Susen, Lohmann Katja, Kaiser Frank J
Section for Functional Genetics at the Institute for Human Genetics, University of Lübeck, Lübeck 23538, Germany.
Institute for Cardiogenetics, University of Lübeck, Lübeck 23538, Germany.
Hum Mol Genet. 2017 Aug 1;26(15):2975-2983. doi: 10.1093/hmg/ddx187.
Thanatos-associated protein domain containing, apoptosis-associated protein 1 (THAP1), the gene mutated in DYT6 dystonia, encodes a transcription factor. While the N-terminal THAP domain allows for specific DNA-binding, the functional relevance of the other regions is largely unknown. The C-terminus contains a 4-amino-acid-spanning host cell factor 1 (HCFC1)-binding domain (HBM) that mediates the interaction with HCFC1. Interestingly, three mutations affecting the HBM (p.N136S, p.N136K, p.Y137C) have been reported in dystonia patients. We investigated the consequences of these mutations on the interaction of THAP1 with HCFC1 and demonstrated that all three mutations abolished HCFC1-THAP1 complex formation. Notably, HCFC1 co-localization was found in >90% of the almost 3,500 chromatin regions loaded with THAP1 in publicly available genome-wide ChIP data. By siRNA-mediated depletion of HCFC1, we detected an increase of THAP1 expression, indicating a co-repressor activity of HCFC1 for THAP1. Quantitative ChIP on selected promoters revealed that none of the mutations significantly decreased the DNA-binding ability of THAP1 while HCFC1 binding was highly reduced. Our findings indicate a THAP1-mediated recruitment of HCFC1 to THAP1 target sites. Of note, dystonia-causing mutations within the HBM in THAP1 abolished this interaction. Thus, we demonstrate disrupted THAP1-HCFC1 complex formation as another mechanism of dystonia-causing mutations leading to transcriptional dysregulation.
含死亡相关蛋白结构域的凋亡相关蛋白1（THAP1）是DYT6肌张力障碍中发生突变的基因，编码一种转录因子。虽然N端的THAP结构域允许特异性DNA结合，但其他区域的功能相关性在很大程度上尚不清楚。C端包含一个跨4个氨基酸的宿主细胞因子1（HCFC1）结合结构域（HBM），该结构域介导与HCFC1的相互作用。有趣的是，在肌张力障碍患者中报道了三个影响HBM的突变（p.N136S、p.N136K、p.Y137C）。我们研究了这些突变对THAP1与HCFC1相互作用的影响，结果表明这三个突变均消除了HCFC1-THAP1复合物的形成。值得注意的是，在公开的全基因组ChIP数据中，在近3500个加载有THAP1的染色质区域中，>90%发现了HCFC1共定位。通过siRNA介导的HCFC1缺失，我们检测到THAP1表达增加，表明HCFC1对THAP1具有共抑制活性。对选定启动子进行的定量ChIP显示，这些突变均未显著降低THAP1的DNA结合能力，而HCFC1结合则大幅减少。我们的研究结果表明，THAP1介导HCFC1募集到THAP1靶位点。值得注意的是，THAP1中HBM内导致肌张力障碍的突变消除了这种相互作用。因此，我们证明THAP1-HCFC1复合物形成中断是导致肌张力障碍的突变导致转录失调的另一种机制。
