tRNA m1A modification ensures HSPC production via modulating Nrf1 translation in zebrafish.

During embryogenesis, nascent hematopoietic stem and progenitor cells (HSPCs) arise from hemogenic endothelium via endothelial-to-hematopoietic transition (EHT). While this process is orchestrated by multiple intrinsic factors, the role of tRNA-mediated translational control during EHT remains poorly understood. Here, we identify tRNA m1A58 as a predominant tRNA modification in specifying HSPC fate in zebrafish embryos. Depletion of trmt61a compromises HSPC production in the aorta-gonad-mesonephros (AGM) region, accompanied by attenuated tRNA m1A58 levels and evident p53-dependent apoptosis. Mechanistically, Trmt61a-mediated tRNA m1A58 modification enhances translation efficiency of nuclear respiratory factor 1 (Nrf1), a key regulator of mitochondrial biogenesis. Consequently, trmt61a deficiency leads to mitochondrial dysfunction and compromises cell survival, ultimately impairing HSPC production. Our findings establish that tRNA m1A58 modification is essential for HSPC generation by supporting translation efficiency, providing new insights into improved strategies for in vitro HSPC induction.