Cell Culture Technology, Faculty of Technology, Bielefeld University, Germany.
Bielefeld University, Center for Biotechnology (CeBiTec), Germany.
Biotechnol J. 2018 Mar;13(3):e1700232. doi: 10.1002/biot.201700232. Epub 2017 Dec 7.
Promoters play a pivotal role in integrating and processing the signals related to transcription initiation. Strong natural viral promoters, such as hCMV or SV40E, have been routinely employed to achieve a high rate of gene expression in ubiquitously used Chinese hamster ovary (CHO) cells. However, viral promoters are susceptible to epigenetic silencing and lack precise regulation levers. This has paved the way to more sensible control elements: endogenous, inducible, and synthetic promoters. In this review we summarize and discuss the use of natural viral, mammalian, and endogenous promoters, as well as recent advances in synthetic promoters and inducible systems for protein expression in CHO cells. Not only the level of transcription, but its long-term stability is crucial for recombinant protein production. Epigenetic chromatin-modifying elements, such as ubiquitously acting chromatin opening elements (UCOEs), matrix attachment regions (MARs), insulators and stabilizing anti-repressors (STARs) significantly improve transcription levels over extended cultivation time and are also discussed here. This review provides up-to date information to facilitate the choice of a suitable promoter and adjacent chromatin-modifying elements to maximize transgene expression as well as ensure long-term expression stability in CHO cell culture.
启动子在整合和处理与转录起始相关的信号方面起着关键作用。强的天然病毒启动子，如 hCMV 或 SV40E，已被常规用于实现普遍使用的中国仓鼠卵巢（CHO）细胞中的高基因表达率。然而，病毒启动子易受表观遗传沉默的影响，并且缺乏精确的调控手段。这为更合理的控制元件铺平了道路：内源性、诱导性和合成启动子。在这篇综述中，我们总结和讨论了天然病毒、哺乳动物和内源性启动子的使用，以及最近在 CHO 细胞中用于蛋白质表达的合成启动子和诱导系统的进展。不仅转录水平，而且其长期稳定性对于重组蛋白生产至关重要。表观遗传染色质修饰元件，如普遍作用的染色质开放元件（UCOE）、基质附着区（MAR）、绝缘子和稳定的抗阻遏物（STAR），在延长培养时间内显著提高转录水平，本文也对此进行了讨论。本综述提供了最新信息，以方便选择合适的启动子和相邻的染色质修饰元件，以最大限度地提高转基因表达，并确保 CHO 细胞培养中的长期表达稳定性。
