Fujita Toshitsugu, Schlegel Werner
University of Geneva, Faculty of Medicine, Geneva, Switzerland.
J Recept Signal Transduct Res. 2010 Feb;30(1):31-42. doi: 10.3109/10799890903517921.
Transcription of eukaryotic genes by RNA polymerase II (pol II) is a complex, highly regulated multiphasic process. Pol II pauses in the proximity of the promoter on a large fraction of transcribed genes. Transcription initiation and elongation of transcripts are under distinct control. Induced gene expression can thus be due to enhanced initiation and/or stimulated elongation. Pausing and resumption of the elongation of transcripts is under the control of transcription elongation factors. Three of them, P-TEFb, DSIF, and NELF have been well characterized as protein complexes with multiple general but also gene specific functions. Elongation factors execute checkpoint functions but serve also as targets for signaling processes which regulate gene expression. Due to the general importance of transcription elongation factors, it is difficult to delineate the mechanisms by which elongation of specific genes is regulated by specific intracellular signals. However, it is clear that the controlled pausing of pol II provides an opportunity to finely control timing and quantity of transcriptional output.
RNA聚合酶II（pol II）对真核基因的转录是一个复杂、高度调控的多阶段过程。在很大一部分转录基因中，pol II会在启动子附近暂停。转录本的起始和延伸受到不同的控制。因此，诱导基因表达可能是由于起始增强和/或延伸受到刺激。转录本延伸的暂停和恢复受转录延伸因子的控制。其中三种，即P-TEFb、DSIF和NELF，作为具有多种一般功能但也具有基因特异性功能的蛋白质复合物，已得到充分表征。延伸因子执行检查点功能，但也作为调节基因表达的信号传导过程的靶点。由于转录延伸因子具有普遍重要性，因此难以描绘特定基因的延伸是如何由特定细胞内信号调控的机制。然而，很明显，pol II的受控暂停为精确控制转录输出的时间和数量提供了一个机会。
