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Disuse osteoporosis (DOP) is a common complication resulting from the lack of or disuse of mechanical loading and has been unsatisfactorily treated. We hypothesized that exosomes derived from human umbilical cord mesenchymal stem cells (HUCMSCs) could reduce bone marrow mesenchymal stem cell (BMSC) apoptosis in rat DOP via the miR-1263/Mob1/Hippo signaling pathway. To evaluate the function of exosomes derived from HUCMSCs (HUCMSC-Exos) in DOP, hind limb unloading (HLU)-induced DOP rat models were prepared. In vitro, the proliferation of BMSCs were evaluated using CCK-8 assays. Further, the apoptosis of BMSCs were evaluated using annexin V–FITC assay and Western blots. In vivo, the protective effects of HUCMSC-Exos were evaluated using HE staining and microCT analysis. The underlying molecular mechanism of exosome action on BMSC apoptosis through the miR-1263/Mob1/Hippo pathway was also investigated by high-throughput RNA sequencing, luciferase reporter assays, RNA-pull down assays and Western blots. The RNA-seq and q-PCR results showed that the level of miR-1263 was most abundant among differentially expressed microRNAs. Exosomal miR-1263 could bind to the 3′untranslated region (3′ UTR) of Mob1 and exert its function by directly targeting Mob1 in recipient cells. The inhibition of Mob1 could activate YAP expression. Hippo inhibition reversed the in vitro HLU-induced apoptotic effect on BMSCs. The microCT and HE staining results indicated that HUCMSC-Exos ameliorated DOP in vivo. Exosomes derived from HUCMSCs are effective at inhibiting BMSC apoptosis and preventing rat DOP. This mechanism is mediated by the miR-1263/Mob1/Hippo signaling pathway. • HUCMSCs derived exosomes inhibit apoptosis in DOP. • Exosomal miR-1263 inhibit BMSCs apoptosis. • Exosomal miR-1263 regulated Mob1 to inhibit apoptosis in DOP. [ABSTRACT FROM AUTHOR]

Local inflammatory responses and alveolar epithelial cells (AECs) apoptosis are both important for the development of the acute lung injury (ALI), a clinically important complication causing high morbidity and mortality, but little is known about the molecular mechanisms underlying the pathogenesis. Herein, we showed for the first time that expression of Metastasis-associated protein 1 (MTA1), a master transcriptional regulator with the ability to regulate divergent cellular pathways by modifying the acetylation status of crucial target genes, was up-regulated in the alveolar cells of the Escherichia coli lipopolysaccharide (LPS)-induced murine ALI model. Inhibition of MTA1 expression by in vivo siRNA treatment exacerbated the pathology of LPS-induced ALI, by selectively promoting the expression of NF-κB-regulated inflammatory cytokines. Moreover, ablation of MTA1 expression promoted the LPS-induced apoptosis in AEC II cells, leaving AEC I cells unaffected. These data collectively underscore an alveolar facet of this important chromatin modifier, which may represent as a novel regulator and a new therapeutic target for the treatment of ALI. [ABSTRACT FROM AUTHOR]