Bone marrow mesenchymal stem cells (BMSCs) support bone formation through osteogenic differentiation and pro-angiogenic paracrine activity, but the mechanisms coordinating these functions remain incompletely understood. Here, we identified dual-specificity phosphatase 26 (DUSP26) as a regulator of BMSC osteogenesis and mitochondrial homeostasis. DUSP26 expression increased during osteogenic differentiation and was reduced in osteoporotic femoral tissues. p300 gain- and loss-of-function experiments, together with analysis of the Yin Yang1(YY1) K183R mutant, supported the conclusion that p300-regulated YY1 lactylation contributes to DUSP26 transcriptional activation. DUSP26 interacted with the mitochondrial processing peptidase subunit beta(PMPCB) and reduced its tyrosine phosphorylation, with mass spectrometry and mutational analyses implicating Y141 as involved in this regulation. Functional assays supported a model in which DUSP26 limits mitochondrial processing peptidase (MPP)-mediated PTEN-induced kinase 1 (PINK1) processing and promotes PINK1-dependent mitophagy, thereby supporting mitochondrial homeostasis. DUSP26 enhanced osteogenic differentiation and the pro-angiogenic activity of BMSC-conditioned medium(CM), whereas its knockdown impaired bone formation and reduced type H vessels in vivo. Furthermore, BMSC-derived exosomes carrying a runt-related transcription factor 2 (RUNX2) promoter-driven DUSP26 plasmid produced preferential transgene expression in osteogenic-lineage cells and attenuated ovariectomy-induced bone loss in mice. These findings link lactylation-associated transcriptional regulation to mitochondrial protein processing and support further preclinical evaluation of DUSP26-directed approaches for osteoporosis.
