Identification of key miRNA‑mRNA pairs in septic mice by bioinformatics analysis

Circ_UBE2D2 Attenuates the Progression of Septic Acute Kidney Injury in Rats by Targeting miR-370-3p/NR4A3 Axis

As circ_UBE2D2 has been confirmed to have targeted binding sites with multiple miRNAs involved in septic acute kidney injury (SAKI), efforts in this study are directed to unveiling the specific role and relevant mechanism of circ_UBE2D2 in SAKI. HK-2 cells were treated with lipopolysaccharide (LPS) to construct SAKI model in vitro. After sh-circ_UBE2D2 was transfected into cells, the transfection efficiency was detected by qRT-PCR, cell viability and apoptosis were determined by MTT assay and flow cytometry, and expressions of Bcl-2, Bax and Cleaved-caspase 3 were quantified by western blot. Target genes associated with circ_UBE2D2 were predicted using bioinformatics analysis. After the establishment of SAKI rat model, HE staining and TUNEL staining were exploited to observe the effect of circ_UBE2D2 on tissue damage and cell apoptosis. The expression of circ_UBE2D2 was overtly elevated in LPS-induced HK-2 cells. Sh-circ_UBE2D2 can offset the inhibition of cell viability and the promotion of cell apoptosis induced by LPS. Circ_UBE2D2 and miR-370-3p as well as miR-370-3p and NR4A3 have targeted binding sites. MiR-370-3p inhibitor reversed the promoting effect of circ_UB2D2 silencing on viability of LPS-treated cells, but shNR4A3 neutralized the above inhibitory effect of miR-370-3p inhibitor. MiR-370-3p inhibitor weakened the down-regulation of NR4A3, Bax and Cleaved caspase-3 and the up-regulation of Bcl-2 induced by circ_UB2D2 silencing, but these trends were reversed by shNR4A3. In addition, sh-circ_UBE2D2 could alleviate the damage of rat kidney tissue. Circ_UBE2D2 mitigates the progression of SAKI in rats by targeting miR-370-3p/NR4A3 axis.

Identification of potential novel biomarkers for abdominal aortic aneurysm based on comprehensive analysis of circRNA-miRNA-mRNA networks

Abdominal aortic aneurysm (AAA) is a life-threatening disorder and, therefore, investigation into its underlying mechanisms in light of the competing endogenous RNAs (ceRNAs) hypothesis has gradually increased. However, there is still lacking systematic analysis on AAA-associated circular RNA (circRNA)-microRNA (miRNA/miR)-messenger RNA (mRNA) interaction networks based on bioinformatics methods. The present study attempted to identify novel molecular biomarkers for AAA by profiling circRNA-miRNA-mRNA networks using three public microarray datasets (GSE7084, GSE57691 and GSE144431). A total of 135 differentially expressed genes (DEGs) and 142 differentially expressed circRNAs were detected using the limma R package with the statistical threshold of P<0.05 and |log₂fold change (FC)| >1.5. In addition, 12 circRNA-miRNA-mRNA axes were identified to construct upregulated and downregulated ceRNA networks using Cytoscape. Based on molecular complex detection algorithm, (hsa_circ_0057691/0092108/0006845/0082182)- miR-330-5p-calponin 1 (CNN1) and (hsa_circ_0061482/0011450/0008351/0004121)-miR-326-CD8a molecule (CD8A) were recognized as the center axes in ceRNA networks. Reverse transcription-quantitative PCR results verified the significant downregulation of CNN1 and upregulation of CD8A in human AAA tissues (P<0.05). In addition, four upregulated circRNA/mRNA axes, and five downregulated circRNA/mRNA axes were revealed to have possible biological functions in the pathogenesis of AAA using the Cytoscape software. Receiver operating characteristic analysis demonstrated the accuracy of these nine DEGs involved in these axes for AAA diagnosis with area under the curves >0.80. The present study revealed novel circRNA-miRNA-mRNA networks associated with AAA, especially for CNN1 and CD8A axes with the potential function of ‘focal adhesion’ and ‘immune response’, respectively. Overall, the present findings may provide evidence to explore the implicated ceRNAs in the molecular mechanisms and as novel biomarkers for AAA.