Circular RNA Plek promotes fibrogenic activation by regulating the miR-135b-5p/TGF-βR1 axis after spinal cord injury

Objectives: The spinal cord rarely repairs itself when damaged; however, methods for encouraging nerves to regrow are on the horizon. Although circular RNAs (circRNAs) contribute to various biological processes, including neuronal processes, their functions in the subacute phase of spinal cord injury (SCI) have not been elucidated. In this study, we identified a novel circRNA, named CircPlek, with increased expression in spinal tissues after SCI. Materials and Methods: We predicted a regulatory relationship between CircPlek and miR-135b-5p, which showed the most obvious decrease in post-SCI expression. We established the CircPlek/miR-135b-5p/transforming growth factor-beta receptor type I (TGF-beta R1) axis using a bioinformatics approach and further evaluated the potential function of the interaction network in vitro. Results: We confirmed that in TGF-beta 1-induced fibroblasts, the overexpression of miR-135b-5p or/and inhibition of CircPlek inhibited fibrosis activation via the Smad pathway. Inhibitors of miR-135b-5p had antagonistic effects on CircPlek. Conclusions: the CircPlek/miR-135b-5p/TGF-beta R1 axis may exert important functions in SCI and is a potential therapeutic target.

Automated summary

A novel circRNA, named CircPlek, was identified with increased expression in spinal tissues after SCI, potentially involving a regulatory relationship with miR-135b-5p and TGF-β R1. Experimental results showed that the CircPlek/miR-135b-5p/TGF-β R1 axis may play an important role in controlling the pathogenesis of SCI.