Background: Some circular RNAs (circRNAs) are reported to attend to the pathogenesis of pneumonia. This study tested the impact of circRNA ankyrin repeat domain 36 (circANKRD36) on human embryonic lung fibroblast MRC-5 cell injury irritated by lipopolysaccharide (LPS).
Methods: After LPS irritation, viability, apoptosis, ROS, protein, and cytokines, along with circANKRD36 were tested by CCK-8, Annexin V-FITC, DCFH-DA, and ELISA or Western blot. si-circANKRD36 and microRNA-31-3p/5p (miR-31-3p/5p) inhibitor were applied to silence circANKRD36 and miR-31-3p/5p. miR-31-3p/5p mimic was utilized to upregulate miR-31-3p/5p. RT-qPCR was used to detect miRNAs. The relationship between miRNAs and MyD88 or IL-34 was analyzed by luciferase activity reporter assay.
Results: LPS aroused a decrease in viability, increases in apoptosis, ROS, and IL-6, IL-8, and TNF-α, along with circANKRD36, and activation of NF-κB pathway. Silencing circANKRD36 weakened the above-mentioned influences of LPS. Moreover, silencing circANKRD36 hoisted miR-31-3p expression. Silencing miR-31-3p mitigated the impacts of circANKRD36 silence on LPS-irritated MRC-5 cells. Besides, MyD88 was a downstream target of miR-31-3p, and 3'UTR of IL-34 mRNA was targeted by miR-31-5p. LPS induced the accumulation of MyD88. Silencing MyD88 was constructive to maintain cell viability, retard apoptosis and inhibit adverse oxidation and inflammation.
Conclusion: This research verified that silencing circANKRD36 could weaken LPS-irritated MRC-5 cell injury via regulating miR-31/MyD88-mediated repression of NF-κB pathway.
Keywords: MyD88; NF-κB pathway; circular RNA ankyrin repeat domain 36; human embryonic lung fibroblast cells; microRNA-31; pneumonia.
© 2019 International Union of Biochemistry and Molecular Biology.