Division of Biochemistry Mannheim Institute for Innate Immunoscience (MI3) and Mannheim Cancer Center (MCC), Medical Faculty Mannheim of Heidelberg University, Mannheim, Germany.
Center for Molecular Biology of Heidelberg University (ZMBH), DKFZ-ZMBHAlliance, Heidelberg, Germany.
RNA Biol. 2022;19(1):437-452. doi: 10.1080/15476286.2022.2048562. Epub 2021 Dec 31.
The transcription factor p53 exerts its tumour suppressive effect through transcriptional activation of numerous target genes controlling cell cycle arrest, apoptosis, cellular senescence and DNA repair. In addition, there is evidence that p53 influences the translation of specific mRNAs, including translational inhibition of ribosomal protein synthesis and translational activation of MDM2. A challenge in the analysis of translational control is that changes in mRNA abundance exert a kinetic (passive) effect on ribosome densities. In order to separate these passive effects from active regulation of translation efficiency in response to p53 activation, we conducted a comprehensive analysis of translational regulation by comparative analysis of mRNA levels and ribosome densities upon DNA damage induced by neocarzinostatin in wild-type and TP53 HCT116 colorectal carcinoma cells. Thereby, we identified a specific group of mRNAs that are preferentially translated in response to p53 activation, many of which correspond to p53 target genes including MDM2, SESN1 and CDKN1A. By subsequent polysome profile analysis of SESN1 and CDKN1A mRNA, we could demonstrate that p53-dependent translational activation relies on a combination of inducing the expression of translationally advantageous isoforms and -acting mechanisms that further enhance the translation of these mRNAs.
转录因子 p53 通过转录激活众多控制细胞周期停滞、细胞凋亡、细胞衰老和 DNA 修复的靶基因发挥其肿瘤抑制作用。此外，有证据表明 p53 影响特定 mRNA 的翻译，包括核糖体蛋白合成的翻译抑制和 MDM2 的翻译激活。在翻译控制分析中面临的一个挑战是，mRNA 丰度的变化对核糖体密度产生动力学（被动）影响。为了将这些被动效应与 p53 激活时对翻译效率的主动调节区分开来，我们通过比较新制癌菌素诱导的野生型和 TP53 HCT116 结直肠癌细胞中的 DNA 损伤后 mRNA 水平和核糖体密度，对翻译调控进行了全面分析。由此，我们确定了一组特定的 mRNAs，它们可优先响应 p53 激活进行翻译，其中许多对应于 p53 靶基因，包括 MDM2、 SESN1 和 CDKN1A。通过对 SESN1 和 CDKN1A mRNA 的后续多核糖体谱分析，我们可以证明 p53 依赖性翻译激活依赖于诱导有利翻译的异构体表达的组合，以及进一步增强这些 mRNA 翻译的作用机制。
