Figure 4.

IL‐6 induced IDD through YAP1/β‐catenin signaling. (a) NP cells were cultured with or without 100 ng/ml IL‐6 for 48 hr, YAP1 and β‐catenin were detected by western blot. (b) NP cells were cultured with 100 ng/ml IL‐6, after 60 min or 120 min. The cells were fixed and stained with antibodies against YAP1 (green) and β‐catenin (red), and the nucleus was stained with DAPI (blue). (c) NP cells were cultured with or with 100 ng/ml IL‐6; Co‐IP was performed to detect the interaction between YAP1 and β‐catenin. (d) NP cells were transfected with scramble sequence or β‐catenin siRNA (si‐β‐catenin); qPCR and western blot showed that β‐catenin was knocked down in NP cells. (e) NP cells were pretransfected with si‐β‐catenin for 12 hr; then they were treated with IL‐6. Col‐II, Aggrecan, MMP‐13 were detected by qPCR after 48 hr. (f) NP cells were transfected with control plasmid, YAP1 plasmid or YAP1 plasmid and si‐β‐catenin for 48 hr; then Col‐II, Aggrecan, MMP‐13 were detected by qPCR. Data represent means ± standard deviation of three independent experiments performed in triplicate (n = 3). *p < .05, **p < .01 indicates significant differences between groups. DAPI: 4′,6‐diamidino‐2‐phenylindole; IDD: intervertebral disc degeneration; IL‐6: interleukin 6; MMP‐13: matrix metalloproteinases 13; NP cells: nucleus pulposus cells; siRNA: small interfering RNA; YAP1: yes‐associated protein 1 [Color figure can be viewed at wileyonlinelibrary.com]