No abstract

Extracellular vesicles (EVs) including exosomes can serve as mediators of cell–cell communication under physiological and pathological conditions. However, cargo molecules carried by EVs to exert their functions, as well as mechanisms for their regulated release and intake, have been poorly understood. In this study, we examined the effects of endothelial cells-derived EVs on neurons suffering from oxygen-glucose deprivation (OGD), which mimics neuronal ischemia-reperfusion injury in human diseases. In a human umbilical endothelial cell (HUVEC)–neuron coculture assay, we found that HUVECs reduced apoptosis of neurons under OGD, and this effect was compromised by GW4869, a blocker of exosome release. Purified EVs could be internalized by neurons and alleviate neuronal apoptosis under OGD. A miRNA, miR-1290, was highly enriched in HUVECs-derived EVs and was responsible for EV-mediated neuronal protection under OGD. Interestingly, we found that OGD enhanced intake of EVs by neurons cultured in vitro. We examined the expression of several potential receptors for EV intake and found that caveolin-1 (Cav-1) was upregulated in OGD-treated neurons and mice suffering from middle cerebral artery occlusion (MCAO). Knock-down of Cav-1 in neurons reduced EV intake, and canceled EV-mediated neuronal protection under OGD. HUVEC-derived EVs alleviated MCAO-induced neuronal apoptosis in vivo. These findings suggested that ischemia likely upregulates Cav-1 expression in neurons to increase EV intake, which protects neurons by attenuating apoptosis via miR-1290.

Rationale: Macrophages play multi-dimensional roles in hepatic fibrosis. Studies have implicated Notch signaling mediated by the transcription factor RBP-J in macrophage activation and plasticity. Additionally, we have previously shown that myeloid-specific disruption of RBP-J can ameliorate hepatic fibrosis in mice. Accordingly, we next asked whether blocking Notch signaling in macrophages could serve as a therapeutic strategy to treat hepatic fibrosis. In this study, we used a combination of transcription factor decoy oligodeoxynucleotides (ODNs) and exosomes to test this possibility. Methods: Hairpin-type decoy oligodeoxynucleotides (ODNs) were designed for the transcription factor RBP-J. The effects of RBP-J decoy ODNs on Notch signaling were evaluated by western blot, quantitative RT-PCR, luciferase reporter assays, and electrophoretic mobility shift assays. ODNs were loaded into HEK293T-derived exosomes by electroporation. A hepatic fibrosis mouse model was established by the intraperitoneal injection of carbon tetrachloride or bile duct ligation. Mice with hepatic fibrosis were administered exosomes loaded with RBP-J decoy ODNs via tail vein injection. The in vivo distribution of exosomes was analyzed by fluorescence labeling and imaging. Liver histology was examined using hematoxylin and eosin, Sirius red, and Masson staining, as well as immunohistochemical staining for Col1α1 and αSMA. Results: We found that RBP-J decoy ODNs could be efficiently loaded into exosomes and inhibit the activation of Notch signaling. Furthermore, exosomes administered via the tail vein were found to be primarily taken up by hepatic macrophages in mice with liver fibrosis. Importantly, RBP-J decoy ODNs delivered by exosomes could efficiently inhibit Notch signaling in macrophages and ameliorate hepatic fibrosis in mice. Conclusions: Combined, our data showed that the infusion of exosomes loaded with RBP-J decoy ODNs represents a promising therapeutic strategy for the treatment of hepatic fibrosis.

Formation of glioma stem cells (GSCs) is considered as one of the main reasons of temozolomide (TMZ) resistance in glioma patients. Recent studies have shown that tumor microenvironment-derived signals could promote GSCs formation. But the critical molecule and underlying mechanism for GSCs formation after TMZ treatment is not entirely identified. Our study showed that TMZ treatment promoted GSCs formation by glioma cells; TMZ treatment of biopsy-derived glioblastoma multiforme cells upregulated HMGB1; HMGB1 altered gene expression profile of glioma cells with respect to mRNA, lncRNA and miRNA. Furthermore, our results showed that TMZ-induced HMGB1 increased the formation of GSCs and when HMGB1 was downregulated, TMZ-mediated GSCs formation was attenuated. Finally, we showed that the effect of HMGB1 on glioma cells was mediated by TLR2, which activated Wnt/β-catenin signaling to promote GSCs. Mechanistically, we found that HMGB1 upregulated NEAT1, which was responsible for Wnt/β-catenin activation. In conclusion, TMZ treatment upregulates HMGB1, which promotes the formation of GSCs via the TLR2/NEAT1/Wnt pathway. Blocking HMGB1-mediated GSCs formation could serve as a potential therapeutic target for preventing TMZ resistance in GBM patients.