College of Life Sciences, TaiKang Center for Life and Medical Sciences, RNA Institute, Hubei Key Laboratory of Cell Homeostasis, Wuhan University, Wuhan, China; Frontier Science Center for Immunology and Metabolism, State Key Laboratory of Virology, Wuhan University, Wuhan, China.
Institute of Advanced Studies, Wuhan University, Wuhan, China.
Mol Cell. 2023 Dec 21;83(24):4494-4508.e6. doi: 10.1016/j.molcel.2023.10.040. Epub 2023 Nov 27.
In the cytoplasm, mRNAs are dynamically partitioned into translating and non-translating pools, but the mechanism for this regulation has largely remained elusive. Here, we report that mA regulates mRNA partitioning between polysome and P-body where a pool of non-translating mRNAs resides. By quantifying the mA level of polysomal and cytoplasmic mRNAs with mA-LAIC-seq and mA-LC-MS/MS in HeLa cells, we observed that polysome-associated mRNAs are hypo-mA-methylated, whereas those enriched in P-body are hyper-mA-methylated. Downregulation of the mA writer METTL14 enhances translation by switching originally hyper-mA-modified mRNAs from P-body to polysome. Conversely, by proteomic analysis, we identify a specific mA reader IGF2BP3 enriched in P-body, and via knockdown and molecular tethering assays, we demonstrate that IGF2BP3 is both necessary and sufficient to switch target mRNAs from polysome to P-body. These findings suggest a model for the dynamic regulation of mRNA partitioning between the translating and non-translating pools in an mA-dependent manner.
在细胞质中，mRNA 被动态地分配到翻译和非翻译池中，但这种调节的机制在很大程度上仍未被揭示。在这里，我们报告说 mA 调节 mRNA 在多核糖体和 P 体之间的分配，非翻译的 mRNAs 就存在于 P 体中。通过在 HeLa 细胞中使用 mA-LAIC-seq 和 mA-LC-MS/MS 定量测定多核糖体和细胞质 mRNA 的 mA 水平，我们观察到与多核糖体相关的 mRNA 是低 mA 甲基化的，而那些在 P 体中富集的则是高 mA 甲基化的。mA 书写器 METTL14 的下调通过将原本高 mA 修饰的 mRNA 从 P 体切换到多核糖体来增强翻译。相反，通过蛋白质组学分析，我们鉴定了一个在 P 体中富集的特定 mA 阅读器 IGF2BP3，并通过敲低和分子牵引实验，我们证明了 IGF2BP3 是将靶 mRNA 从多核糖体切换到 P 体所必需的和充分的。这些发现表明了一种模型，即 mA 依赖性地调节翻译和非翻译池之间的 mRNA 分配的动态平衡。
