Figure 6. CircPlek/miR-135b-5p/TGF-βR1 axis regulated the progression of fibrosis. (A) Western blot showing fibronectin and collagen I protein levels in the control, SCI model, SCI + mimic NC, and SCI + miR-135b-5p mimics groups. (B) Western blotting showing fibronectin and collagen I protein levels in the control, SCI model, SCI + siCircRNA NC, and SCI + siCircPlek groups. (C) After co-transfection of spinal fibroblasts with siCircPlek and an miR-135b-5p inhibitor with or without SCI, fibronectin and collagen I protein levels were measured using western blotting. (D) Proposed model of the function of CircPlek in the regulation of fibrosis via the miR-135b-5p/TGF-βR1 axis in spinal fibroblasts. Under SCI, the expression of CircPlek was upregulated. Elevated CircPlek attracting miR-135b-5p, which bound to TGF-βR1, consequently inducing the activation of fibroblasts and fibrous scar formation.