MiR-199a-3p in mouse bone marrow mesenchymal stem cell exosomes increases epithelial sodium channel expression in lung injury.

Acute lung injury (ALI) causes significant morbidity and mortality in critically ill patients, which often presents with extensive accumulation of activated inflammatory cells and diffused alveolar damage accompanied by oxidative stress. Exosomes are nanovesicles, which have notable anti-inflammatory and repair properties, thus alleviating the symptoms of ALI. Epithelial sodium channel (ENaC) is essential for the transepithelial absorption of Na+ and fluid from alveolar spaces. We studied the effects of bone marrow mesenchymal stem cell exosomes (BMSC-exo) on the apoptosis and protein expression of ENaC in primary mouse alveolar epithelial type 2 cells (AT 2 cells). Moreover, the change of miR-199a-3p in AT 2 cells was detected by qRT-PCR, and we studied the regulation of miR-199a-3p on ENaC protein expression. Our results demonstrated that BMSC-exo could not only improve viability and reduce apoptosis in AT 2 cells, but also enhance the expression of ENaC protein and miR-199a-3p. Meanwhile, the upregulation of miR-199a-3p resulted in increased expression of ENaC protein. In summary, the BMSC-exo could participate in the regulation of ENaC through miR-199a-3p originated from BMSC-exo, thereby providing a new pharmacological tool for the treatment of ALI.

Airway Basal Cells Mediate Hypoxia-Induced EMT by Increasing Ribosome Biogenesis.

Excessive secretion of airway mucus and fluid accumulation are the common features of many respiratory diseases, which, in turn, induce cell hypoxia in the airway epithelium, resulting in epithelial-mesenchymal transition (EMT) and ultimately fibrosis. However, the mechanisms of EMT induced by hypoxia in the airway are currently unclear. To mimic the status of edematous fluid retention in the airway, we cultured primary mouse tracheal epithelial cells (MTECs) in a liquid-liquid interface (LLI) mode after full differentiation in a classic air-liquid interface (ALI) culture system. The cell hypoxia was verified by the physical characteristics and lactate production in cultured medium as well as HIF expression in MTECs cultured by LLI mode. EMT was evidenced and mainly mediated by basal cells, supported by flow cytometry and immunofluorescence assay. The differently expressed genes of basal and other airway epithelial cells were found to be enriched in the ribosome by our analysis of an MTEC single-cell RNA sequencing data set and Myc, the global regulator of ribosome biogenesis was identified to be highly expressed in basal cells. We next separated basal cells from bulk MTECs by flow cytometry, and the real-time PCR results showed that ribosome biogenesis was significantly upregulated in basal cells, whereas the inhibition of ribosome biogenesis alleviated the phosphorylation of the mammalian target of rapamycin/AKT and abrogated hypoxia-induced EMT in MTECs. Collectively, these observations strongly suggest that basal cells in the airway epithelium may mediate the process of hypoxia-induced EMT, partly through enhancing ribosome biogenesis.

Transcriptomic analysis of cut tree peony with glucose supply using the RNA-Seq technique.

KEY MESSAGE: Several unigenes encoding ACS and ERF involved in ethylene biosynthesis and signal transduction were greatly down-regulated in the petal transcriptome of cut tree peony 'Luoyang Hong' with glucose treatment. Glucose also repressed stress-related transcription factor genes DREB, CBF, NAC, WRKY and bHLH. Tree peony (Paeonia suffruticosa Andrews) is a famous traditional flower in China. Glucose supply prolonging vase life of cut tree peony flowers is associated with its role in the suppression of sensitivity to ethylene and ethylene production, but the regulation mechanism of sugar on ethylene biosynthesis and signaling is unclear. In the present work, a normalized cDNA pool was constructed as the reference transcriptome from mixed petals of different developmental cut tree peony 'Luoyang Hong' and sequenced using the Illumina HiSeq™ 2000 platform. We obtained 33,117 unigenes annotated with public protein databases. In addition, the transcriptome change in petals of cut tree peony with glucose supply and the control treatment was investigated. With non-redundant annotation, 173 differentially expressed genes were identified, with 41 up-regulated genes and 132 down-regulated genes. According to RNA-Seq data and real-time quantitative polymerase chain reaction validation, one unigene encoding ACS, a key ethylene synthetic enzyme, and four unigenes encoding ERF, which is involved in ethylene signal transduction was greatly down-regulated with glucose treatment. Furthermore, stress-related transcription factor genes DREB, CBF, NAC, WRKY and bHLH were also repressed with glucose supply, as well as several other stress-responsive and stress-tolerance genes, indicating that glucose supply probably releases the effects induced by various environmental stress. All the results and analysis are valuable resources for better understanding of the beneficial influence of exogenous sugars on cut tree peony.