Stowers Institute for Medical Research, Kansas City, MO, 64110, USA.
Department of Pathology & Laboratory Medicine, University of Kansas Medical Center, Kansas City, KS, 66160, USA.
Sci Rep. 2018 Sep 12;8(1):13712. doi: 10.1038/s41598-018-32009-w.
HDAC1 and HDAC2 are components of several corepressor complexes (NuRD, Sin3, CoREST and MiDAC) that regulate transcription by deacetylating histones resulting in a more compact chromatin environment. This limits access of transcriptional machinery to genes and silences transcription. While using an AP-MS approach to map HDAC1/2 protein interaction networks, we noticed that N-terminally tagged versions of HDAC1 and HDAC2 did not assemble into HDAC corepressor complexes as expected, but instead appeared to be stalled with components of the prefoldin-CCT chaperonin pathway. These N-terminally tagged HDACs were also catalytically inactive. In contrast to the N-terminally tagged HDACs, C-terminally tagged HDAC1 and HDAC2 captured complete histone deacetylase complexes and the purified proteins had deacetylation activity that could be inhibited by SAHA (Vorinostat), a Class I/II HDAC inhibitor. This tag-mediated reprogramming of the HDAC1/2 protein interaction network suggests a mechanism whereby HDAC1 is first loaded into the CCT complex by prefoldin to complete folding, and then assembled into active, functional HDAC complexes. Imaging revealed that the prefoldin subunit VBP1 colocalises with nuclear HDAC1, suggesting that delivery of HDAC1 to the CCT complex happens in the nucleus.
组蛋白去乙酰化酶 1（HDAC1）和组蛋白去乙酰化酶 2（HDAC2）是几种核心抑制复合物（NuRD、Sin3、CoREST 和 MiDAC）的组成部分，这些复合物通过去乙酰化组蛋白来调节转录，从而导致更紧凑的染色质环境。这限制了转录机制对基因的访问，并使转录沉默。在使用 AP-MS 方法绘制 HDAC1/2 蛋白相互作用网络时，我们注意到，N 端标记的 HDAC1 和 HDAC2 版本没有如预期那样组装成 HDAC 核心抑制复合物，而是似乎与 Prefoldin-CCT 伴侣蛋白途径的成分停滞不前。这些 N 端标记的 HDACs 也是无催化活性的。与 N 端标记的 HDACs 相反，C 端标记的 HDAC1 和 HDAC2 捕获了完整的组蛋白去乙酰化酶复合物，并且纯化的蛋白质具有去乙酰化活性，可被 SAHA（伏立诺他）抑制，SAHA 是一种 I/II 类 HDAC 抑制剂。这种标签介导的 HDAC1/2 蛋白相互作用网络的重新编程表明了一种机制，即通过 Prefoldin 将 HDAC1 首先加载到 CCT 复合物中以完成折叠，然后组装成具有活性和功能的 HDAC 复合物。成像显示 Prefoldin 亚基 VBP1 与核内的 HDAC1 共定位，表明 HDAC1 被递送到 CCT 复合物的过程发生在核内。
