Essential role of Dhx16-mediated ribosome assembly in maintenance of hematopoietic stem cells.

Hematopoietic stem cells (HSCs) are vital for the differentiation of all mature blood cells, with their homeostasis being tightly regulated by intrinsic and extrinsic factors. Alternative splicing, mediated by the spliceosome complex, plays a crucial role in regulating HSC homeostasis by increasing protein diversity. This study focuses on the ATP-dependent RNA helicase DHX16, a key spliceosome component, and its role in HSC regulation. Using conditional knockout mice, we demonstrate that loss of Dhx16 in the hematopoietic system results in significant depletion of hematopoietic stem and progenitor cells, bone marrow failure, and rapid mortality. Dhx16-deficient HSCs exhibit impaired quiescence, G2-M phase cell cycle arrest, reduced protein synthesis, abnormal ribosome assembly, increased apoptosis, and decreased self-renewal capacity. Multi-omics analysis identified intron 4 retention in Emg1 mRNA in Dhx16 knockout HSCs, leading to reduced EMG1 protein expression, disrupted ribosome assembly, and nucleolar stress, activating the p53 pathway. Overexpression of Emg1 in Dhx16-deficient HSCs partially restored ribosome assembly and HSC function, suggesting Emg1 as a potential therapeutic target for ribosomopathies. Our findings reveal the critical role of Dhx16 in HSC homeostasis through the regulation of alternative splicing and ribosome assembly, providing insights into the molecular mechanisms underlying hematopoietic diseases and potential therapeutic strategies.