Theodor Boveri Institute and Comprehensive Cancer Center Mainfranken, Biocenter, University of Würzburg, Am Hubland, 97074 Würzburg, Germany.
Faculty of Biological Sciences, University of Leeds, Leeds LS2 9JT, UK; University of Leicester, Leicester LE1 9HN, UK.
Cell Rep. 2017 Dec 19;21(12):3483-3497. doi: 10.1016/j.celrep.2017.11.090.
MYC proteins bind globally to active promoters and promote transcriptional elongation by RNA polymerase II (Pol II). To identify effector proteins that mediate this function, we performed mass spectrometry on N-MYC complexes in neuroblastoma cells. The analysis shows that N-MYC forms complexes with TFIIIC, TOP2A, and RAD21, a subunit of cohesin. N-MYC and TFIIIC bind to overlapping sites in thousands of Pol II promoters and intergenic regions. TFIIIC promotes association of RAD21 with N-MYC target sites and is required for N-MYC-dependent promoter escape and pause release of Pol II. Aurora-A competes with binding of TFIIIC and RAD21 to N-MYC in vitro and antagonizes association of TOP2A, TFIIIC, and RAD21 with N-MYC during S phase, blocking N-MYC-dependent release of Pol II from the promoter. Inhibition of Aurora-A in S phase restores RAD21 and TFIIIC binding to chromatin and partially restores N-MYC-dependent transcriptional elongation. We propose that complex formation with Aurora-A controls N-MYC function during the cell cycle.
MYC 蛋白与活跃的启动子广泛结合,并通过 RNA 聚合酶 II(Pol II)促进转录延伸。为了鉴定介导此功能的效应蛋白,我们在神经母细胞瘤细胞中对 N-MYC 复合物进行了质谱分析。分析表明,N-MYC 与 TFIIIC、TOP2A 和 RAD21(黏合蛋白的一个亚基)形成复合物。N-MYC 和 TFIIIC 结合到数千个 Pol II 启动子和基因间区域的重叠位点。TFIIIC 促进 RAD21 与 N-MYC 靶位点的结合,并且对于 N-MYC 依赖性启动子逃避和 Pol II 的暂停释放是必需的。Aurora-A 在体外与 TFIIIC 和 RAD21 与 N-MYC 的结合竞争,并在 S 期拮抗 TOP2A、TFIIIC 和 RAD21 与 N-MYC 的结合,阻止 Pol II 从启动子上的 N-MYC 依赖性释放。S 期抑制 Aurora-A 可恢复 RAD21 和 TFIIIC 与染色质的结合,并部分恢复 N-MYC 依赖性转录延伸。我们提出,与 Aurora-A 的复合物形成在细胞周期中控制 N-MYC 的功能。