In summary, this study demonstrated that Mtu1 deficiency caused inefficient 2-thiouridine modification of U34 of mitochondrial tRNAGln, tRNAGlu, and tRNALys in both primary mouse bone marrow MSCs and MS5 stromal cells, subsequently impairing mitochondrial translation and mitochondrial ATP production, leading to decreased osteogenesis and osteopenia in the mice. This evidence concerns the gene TRMU and Osteopenia.