Ross J F, Liu X, Dynlacht B D
Department of Molecular and Cellular Biology, Cambridge, Massachusetts 02138, USA.
Mol Cell. 1999 Feb;3(2):195-205. doi: 10.1016/s1097-2765(00)80310-x.
The retinoblastoma tumor suppressor protein (pRB) is a transcriptional repressor, critical for normal cell cycle progression. We have undertaken studies using a highly purified reconstituted in vitro transcription system to demonstrate how pRB can repress transcriptional activation mediated by the E2F transcription factor. Remarkably, E2F activation became resistant to pRB-mediated repression after the establishment of a partial (TFIIA/TFIID) preinitiation complex (PIC). DNase I footprinting studies suggest that E2F recruits TFIID to the promoter in a step that also requires TFIIA and confirm that recruitment of the PIC by E2F is blocked by pRB. These studies suggest a detailed mechanism by which E2F activates and pRB represses transcription without the requirement of histone-modifying enzymes.
视网膜母细胞瘤肿瘤抑制蛋白（pRB）是一种转录抑制因子，对正常细胞周期进程至关重要。我们开展了研究，使用高度纯化的体外重组转录系统来证明pRB如何抑制由E2F转录因子介导的转录激活。值得注意的是，在形成部分（TFIIA/TFIID）预起始复合物（PIC）后，E2F激活对pRB介导的抑制产生了抗性。DNase I足迹研究表明，E2F在一个也需要TFIIA的步骤中将TFIID募集到启动子上，并证实E2F对PIC的募集被pRB阻断。这些研究提示了一种详细的机制，通过该机制E2F激活转录而pRB抑制转录，且无需组蛋白修饰酶。
