Mestre-Fos Santi, Ferguson Lucas, Trinidad Marena I, Ingolia Nicholas T, Cate Jamie H D
Innovative Genomics Institute, University of California, Berkeley, Berkeley, United States.
Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, United States.
Elife. 2025 Jan 29;13:RP102977. doi: 10.7554/eLife.102977.
Stem cell differentiation involves a global increase in protein synthesis to meet the demands of specialized cell types. However, the molecular mechanisms underlying this translational burst and the involvement of initiation factors remains largely unknown. Here, we investigate the role of eukaryotic initiation factor 3 (eIF3) in early differentiation of human pluripotent stem cell (hPSC)-derived neural progenitor cells (NPCs). Using Quick-irCLIP and alternative polyadenylation (APA) Seq, we show eIF3 crosslinks predominantly with 3' untranslated region (3'-UTR) termini of multiple mRNA isoforms, adjacent to the poly(A) tail. Furthermore, we find that eIF3 engagement at 3'-UTR ends is dependent on polyadenylation. High eIF3 crosslinking at 3'-UTR termini of mRNAs correlates with high translational activity, as determined by ribosome profiling, but not with translational efficiency. The results presented here show that eIF3 engages with 3'-UTR termini of highly translated mRNAs, likely reflecting a general rather than specific regulatory function of eIF3, and supporting a role of mRNA circularization in the mechanisms governing mRNA translation.
干细胞分化涉及蛋白质合成的整体增加，以满足特殊细胞类型的需求。然而，这种翻译爆发背后的分子机制以及起始因子的作用在很大程度上仍不清楚。在这里，我们研究了真核起始因子3（eIF3）在人多能干细胞（hPSC）来源的神经祖细胞（NPC）早期分化中的作用。使用快速红外交联免疫沉淀（Quick-irCLIP）和可变聚腺苷酸化（APA）测序，我们发现eIF3主要与多个mRNA异构体的3'非翻译区（3'-UTR）末端交联，靠近聚（A）尾。此外，我们发现eIF3在3'-UTR末端的结合依赖于聚腺苷酸化。通过核糖体分析确定，mRNA的3'-UTR末端的高eIF3交联与高翻译活性相关，但与翻译效率无关。这里呈现的结果表明，eIF3与高翻译mRNA的3'-UTR末端结合，这可能反映了eIF3的一般而非特定调节功能，并支持mRNA环化在控制mRNA翻译机制中的作用。
