SP1 transcriptionally activates NLRP6 inflammasome and induces immune evasion and radioresistance in glioma cells.

Glioma accounts for approximately 80% of all malignant brain tumors. This study aimed to investigate the interaction between specificity protein 1 (SP1) and NLR family pyrin domain containing 6 (NLRP6) and their roles in the activity of glioma cells. Differentially expressed genes in glioma were identified using transcriptome analysis tools, and a protein-protein-interaction network was performed based on the DEGs. SP1 and NLRP6 were abundantly expressed in glioma cells and indicated unfavorable prognosis of patients according to the GEO datasets. SP1could bind to the promoter of NLRP6 and induce its transcriptional activity. Downregulation of SP1 reduced proliferation, migration and invasion of glioma U87 cells in vitro as well as tumorigenesis in vivo. The malignancy of cells was restored after NLRP6 upregulation. Downregulation of SP1 in glioma cells also increased proliferation of CD8+ T cells and the immune activity in U87 cells, and it reduced the radioresistance of U87 cells. However, the immune evasion and radioresistance of glioma cells were restored upon NLRP6 upregulation. NLRP6 mediated the innate immune pathway through an ASC/caspase-1/IL-1ß axis. To conclude, this study suggested that SP1 interacts with NLRP6 inflammasome to enhance malignant behaviors, immune evasion and radioresistance in glioma cells.

Exosomal miR-199a-5p derived from endothelial cells attenuates apoptosis and inflammation in neural cells by inhibiting endoplasmic reticulum stress.

Remote ischemic post-conditioning (RIPostC) is a technique that can protect vital organs in an indirect manner, the effects of which are exerted by the long-distance exosome-mediated transfer of functional factors. In the current study, the possible mechanism driving the function of RIPostC was explored using an in vitro system by focusing on miR-199a-5p and its downstream effectors involved in endoplasmic reticulum (ER) stress. Human umbilical vein endothelial cells (HUVECs) were administrated with hypoxia/re-oxygenation (H/R) process and exosomes were collected from the H/R-treated HUVECs. The levels of miR-199a-5p in HUVECs and exosomes were detected. Afterwards, H/R-treated SH-SY5Y neural cells was incubated with H/R HUVEC-derived exosomes, and the effect on cell apoptosis, inflammation, and miR-199a-5p-mediated ER stress was assessed. Furthermore, the key role of miR-199a-5p suppression in the protection effect of HUVEC-derived exosomes was validated by transfecting neural cells with specific inhibitor. The results showed that H/R administration increased miR-199a-5p levels both in HUVECs and exosomes. The incubation of neural cells with exosomes suppressed cell apoptosis and inflammation, and induced the level of miR-199a-5p, which led to suppressed ER stress. Moreover, the transfection of miR-199a-5p inhibitor blocked the anti-H/R function of exosomes. Taken together, the findings outlined in the current study showed that the protection effect of HUVEC derived miR-199a-5p on neural cells was exerted via exosome transfer, which then suppressed the ER stress-induced apoptosis and inflammation by targeting BIP.

Functional importance of the TGF-ß1/Smad3 signaling pathway in oxygen-glucose-deprived (OGD) microglia and rats with cerebral ischemia.

We investigated the transforming growth factor-b1 (TGF-ß1)/Smad3 signaling pathway in rats with cerebral ischemia and oxygen-glucose-deprived (OGD) microglia. Cerebral ischemia is a clinical condition that occurs when insufficient blood flows to the brain to maintain metabolic activity. TGF-ß1 is a well-known functional peptide that regulates cell differentiation, migration, proliferation, and apoptosis. In the current study, we determined the infarct size and TGF-ß1/Smad3 protein expression in stroke-induced rats. Apoptosis and TGF-ß1/Smad3 mRNA and protein expression were determined in transfected OGD human microglial cells. TGF-ß1 treatment resulted in smaller infarct regions than in control cells, whereas TGF-ß1 inhibitor treatment resulted in larger infarcts. The TGF-ß1-treated groups showed substantial TGF-ß1 and Smad3 expression by immunofluorescence compared to the controls. Apoptosis was significantly reduced in TGF-ß1- and Smad3-transfected cells, and an increased rate of apoptosis was observed in Smad3 or TGF-ß1 siRNA-transfected cells. TGF-ß1 and Smad3 mRNA and protein expression increased following TGF-ß1 and Smad3 transfection. Taken together, our experimental results show that Smad3 and TGF-ß1 play a protective role against ischemic stroke, as demonstrated by the reduced infarct size. Smad3 and TGF-ß1 expression was increased in cells transfected with TGF-ß1, whereas Smad3 and TGF-ß1 expression was increased in TGF-ß1 inhibitor-transfected cells.