CircPalm2 knockdown alleviates LPS-evoked pulmonary microvascular endothelial cell apoptosis and inflammation via miR-450b-5p/ROCK1 axis

Background: Emerging evidence has revealed that circular RNAs (circRNAs) have roles in regulating the complex pathologies of sepsis-induced acute lung injury (sepsis-ALI). Herein, this work aimed to investigate the potential role and mechanism of circPalm2 in the process of sepsis-ALI.

Methods: Primary mice pulmonary microvascular endothelial cells (MPVECs) in functional group were exposed to lipopolysaccharide (LPS). Levels of genes and proteins were measured by qRT-PCR and western blotting. Functional experiments were conducted using In vitro functional experiments were conducted using cell counting kit-8 assay, 5-ethynyl-2'-deoxyuridine (EdU) assay, flow cytometry and ELISA analysis. The binding between miR-450b-5p and circPalm2 or ROCK1 (Rho Associated Coiled-Coil Containing Protein Kinase 1) was validated using dual-luciferase reporter, RNA immunoprecipitation and pull-down assays.

Results: LPS treatment caused the increase of circPalm2 and ROCK1, as well as the decrease of miR-450b-5p in MPVECs. Knockdown of circPalm2 attenuated LPS-induced proliferation arrest, apoptosis, and production of proinflammatory cytokine IL-6, IL-β and TNF-α in MPVECs. Mechanistically, circPalm2 sequestered miR-450b-5p to up-regulate ROCK1 expression, revealing the circPalm2/miR-450b-5p/ROCK1 feedback loop. Moreover, the protective functions mediated by circPalm2 silencing on MPVECs under LPS exposure were abolished by miR-129-5p inhibition or ROCK1 overexpression.

Conclusion: CircPalm2 knockdown can alleviate LPS-evoked MPVEC apoptosis and inflammation via miR-450b-5p/ROCK1 axis, suggesting the potential involvement of this ceRNA network in sepsis-ALI and a broader approach for the therapy of sepsis-ALI.