Inhibition of miR-34a-5p alleviates hypoxia-reoxygenation injury by enhancing autophagy in steatotic hepatocytes

MicroRNA-34a-5p promotes the progression of osteoarthritis secondary to developmental dysplasia of the hip by restraining SESN2-induced autophagy

Osteoarthritis (OA), a late-stage complication of developmental dysplasia of the hip (DDH), is a key factor leading to further degeneration of joint function. Studies have shown that Sestrin2 (SESN2) is a positive regulator in protecting articular cartilage from degradation. However, the regulatory effects of SESN2 on DDH-OA and its upstream regulators remain obscure. Here, we first identified that the expression of SESN2 significantly decreased in the cartilage of DDH-OA samples, with an expression trend negatively correlated with OA severity. Using RNA sequencing, we identified that the upregulation of miR-34a-5p may be an important factor for the decrease in SESN2 expression. Further exploring the regulation mechanism of miR-34a-5p/SESN2 is of great significance for understanding the mechanism of DDH occurrence and development. Mechanistically, we showed that miR-34a-5p could significantly inhibit the expression of SESN2, thereby promoting the activity of the mTOR signaling pathway. We also found that miR-34a-5p significantly inhibited SESN2-induced autophagy, thereby suppressing the proliferation and migration of chondrocytes. We further validated that knocking down miR-34a-5p in vivo resulted in a significant increase in SESN2 expression and autophagy activity in DDH-OA cartilage. Our study suggests that miR-34a-5p is a negative regulator of DDH-OA, and may provide a new target for the prevention of DDH-OA.

MicroRNA-520d-3p alleviates hypoxia/reoxygenation-induced damage in human cardiomyocytes by targeting ATG-12

Hypoxia/reoxygenation (H/R) induced injury results in extensive damages to myocardial tissue in patients with coronary heart disease, which leads to heart failure. MicroRNA (miRNA) is thought to be associated with myocardial H/R injury. The purpose of this study was to investigate the in vitro role of microRNA-520d-3p in human myocardial cell (HCM) myocardial H/R injury. MTT method and Annexin V-FITC flow cytometry were employed to measure the viability and apoptosis of H/R treated HCM. RT-qPCR was employed to determine miRNA and mRNA expression. MicroRNA-520d-3p mimic and microRNA-520d-3p inhibitor were used to overexpression and inhibit the expression of microRNA-520d-3p. In addition, pcDNA3.1-ATG12 was used to upregulate ATG12 expression. The protein levels of ATG12, Bcl-2 and autophagy related-genes were determined by western blotting. Hypoxia/reoxygenation (H/R) injury could inhibit cell viability, apoptosis and inhibited microRNA-520d-3p expression in HCM. The down-regulation of microRNA-520d-3p inhibited cell viability and induced apoptosis in HCM. The overexpression of microRNA-520d-3p attenuated the effects of H/R treatment on the viability and apoptosis of HCM cells. In addition, microRNA-520d-3p inhibited the expression of autophagy-associated 12 (ATG12). More importantly, H/R treatment could promote autophagy in HCM, and microRNA-520d-3p mimic transfection could significantly reverse this effect. Our result indicated that overexpression of microRNA-520d-3p attenuated the effect of H/R treatments on cell viability, apoptosis and autophagy, through partly regulating ATG12 expression in HCM.

Generation of sphingosine-1-phosphate by sphingosine kinase 1 protects nonalcoholic fatty liver from ischemia/reperfusion injury through alleviating reactive oxygen species production in hepatocytes

BACKGROUND

Nonalcoholic fatty liver (NAFL) is emerging as a leading risk factor of hepatic ischemia/reperfusion (I/R) injury lacking of effective therapy. Lipid dyshomeostasis has been implicated in the hepatopathy of NAFL. Herein, we investigate the bioactive lipids that critically regulate I/R injury in NAFL.

METHODS

Lipidomics were performed to identify dysregulated lipids in mouse and human NAFL with I/R injury. The alteration of corresponding lipid-metabolizing genes was examined. The effects of the dysregulated lipid metabolism on I/R injury in NAFL were evaluated in mice and primary hepatocytes.

RESULTS

Sphingolipid metabolic pathways responsible for the generation of sphingosine-1-phosphate (S1P) were uncovered to be substantially activated by I/R in mouse NAFL. Sphingosine kinase 1 (Sphk1) was found to be essential for hepatic S1P generation in response to I/R in hepatocytes of NAFL mice. Sphk1 knockdown inhibited the hepatic S1P rise while accumulating ceramides in hepatocytes of NAFL mice, leading to aggressive hepatic I/R injury with upregulation of oxidative stress and increase of reactive oxygen species (ROS). In contrast, administration of exogenous S1P protected hepatocytes of NAFL mice from hepatic I/R injury. Clinical study revealed a significant activation of S1P generation by I/R in liver specimens of NAFL patients. In vitro studies on the L02 human hepatocytes consolidated that inhibiting the generation of S1P by knocking down SPHK1 exaggerated I/R-induced damage and oxidative stress in human hepatocytes of NAFL.

CONCLUSIONS

Generation of S1P by SPHK1 is important for protecting NAFL from I/R injury, which may serve as therapeutic targets for hepatic I/R injury in NAFL.

Circ_0009910 promotes imatinib resistance through ULK1-induced autophagy by sponging miR-34a-5p in chronic myeloid leukemia

BACKGROUND

The occurrence in drug resistance of chronic myeloid leukemia (CML) was accompanied by autophagy activation. Abnormal circular RNAs (circRNAs) participated in this progression. This study attempted to investigate the potential role of circ_0009910 in imatinib resistance of CML cells.

METHODS

The expression of circ_0009910 and miR-34a-5p was measured by quantitative real-time polymerase chain reaction (qRT-PCR). The characterization of circ_0009910 was investigated using oligo (dT)18 primers, Actinomycin D and RNase R. Cell viability (IC₅₀ value) and apoptosis were assessed by Cell Counting Kit-8 (CCK8) assay and flow cytometry assay, respectively. The relative protein expression was quantified by western blot. The relationship among miR-34a-5p, circ_0009910 and ULK1 was predicted by online bioinformatics tool, and verified by dual-luciferase reporter assay and RNA immunoprecipitation (RIP).

RESULTS

The expression of circ_0009910 was up-regulated in the serum of imatinib-resistance CML patients and K562/R cells, and associated with unfavorable clinicopathologic features. Circ_0009910 in K562 and K562/R cells was mainly localized in the cytoplasm. Circ_0009910 knockdown inhibited cell proliferation and autophagy, but induced apoptosis in K562/R cells. Circ_0009910 targeted miR-34a-5p to regulate ULK1. MiR-34a-5p depression rescued the effects of circ_0009910 knockdown on apoptosis and autophagy in K562/R cells.

CONCLUSION

Circ_0009910 accelerated imatinib-resistance in CML cells by modulating ULK1-induced autophagy via targeting miR-34a-5p, providing a potential target in imatinib resistance of CML.

Down-Regulation of miR-34a-5p Potentiates Protective Effect of Adipose-Derived Mesenchymal Stem Cells Against Ischemic Myocardial Infarction by Stimulating the Expression of C1q/Tumor Necrosis Factor-Related Protein-9

Adipose-derived stem cells (ADSCs) have shown great promise for the treatment of myocardial infarction (MI), although their potential therapeutic mechanism remains poorly understood. Growing evidence has implicated microRNAs (miRNAs or miRs) in the biological processes whereby ADSCs could ameliorate cardiovascular disease. In this study, we explored the contribution of miR-34a-5p down-regulation to the protective actions of ADSCs against MI. We initially identified the interaction between miR-34a-5p and C1q/tumor necrosis factor-related protein-9 (CTRP9) through in silico analysis. We next tested the effects of miR-34a-5p and CTRP9 on the expression of extracellular signal-regulated kinase 1 (ERK1), matrix metalloproteinase-9 (MMP-9), nuclear factor (erythroid-derived 2)-like 2 (NRF2), and antioxidant proteins [manganese superoxide dismutase (MnSOD), and heme oxygenase-1 (HO-1)] through gain- and loss-of-function tests. In other experiments, we assessed the proliferation, migration, and apoptosis of ADSCs using the EdU assay, scratch test, Transwell assay, and flow cytometry. Finally, we studied whether miR-34a-5p/CTRP9 axis could modulate the protective effect of ADSCs against MI during stem cell transplantation in MI mouse models. miR-34a-5p could target and down-regulate CTRP9 in cardiomyocytes. Down-regulated miR-34a-5p increased the expression of ERK1, MMP-9, NRF2, MnSOD, and HO-1, whereas down-regulation of miR-34a-5p or up-regulation of CTRP9 in vitro promoted ADSC proliferation and migration and inhibited ADSC apoptosis. Moreover, miR-34a-5p down-regulation or CTRP9 up-regulation promoted the protective role of ADSCs against MI damage in vivo. Thus, inhibition of miR-34a-5p may facilitate ADSC’s protective function against MI damage by stimulating the expression of CTRP9.

Rapamycin- and starvation-induced autophagy are associated with miRNA dysregulation in A549 cells

MicroRNAs (miRNAs) are short (20-23 nt) non-coding RNAs that are involved in post-transcriptional regulation of gene expression in multicellular organisms by affecting both the stability and translation of mRNAs. In recent years, deep sequencing of the transcription is being increasingly utilized with the promise of higher sensitivity for the identification of differential expression patterns as well as the opportunity to discover new transcripts, including new alternative isoforms and miRNAs. In this study, miRNAs from A549 cells treated with/without rapamycin or starvation were subject to genome-wide deep sequencing. A total of 1534 miRNAs were detected from the rapamycin- and starvation-treated A549 cells. Among them, 31 miRNAs were consistently upregulated and 131 miRNAs were downregulated in the treated cells when compared with the untreated cells. Gene ontology and Kyoto Encyclopedia of Genes and Genomes pathway analysis of the predicted target genes of the most significantly differentially expressed miRNAs revealed that the autophagy-related miRNAs are involved in cancer pathway. Taken together, our findings indicate that the underlying mechanism responsible for autophagy is associated with dysregulation of miRNAs in rapamycin- or starvation-induced A549 cells.