Fig. 4

IL-20 inhibited axonal regeneration. a Expression of IL-20 and its receptors (IL-20R1, IL-20R2, and IL-22R1) in PC-12 cells and nerve growth factor (NGF)-differentiated PC-12 cells were analyzed using immunocytochemistry staining. Data from one representative experiment of three independent experiments is shown. b NGF-differentiated PC-12 cells were incubated with IL-20, 7E, or IL-20 plus 7E for 72 h. Cell viability was determined using the MTT assay. *P < 0.05 compared with the untreated controls (Ctrl). ^#P < 0.05 compared with the corresponding controls. Data are expressed as mean ± SD and are representative of three independent experiments performed in quadruplicate. c PC-12 cells were treated with NGF or with NGF plus IL-20 (200 ng/ml). Immunofluorescence staining was performed using anti-β-tubulin mAb (green) to mark neurite outgrowth. Data from one representative experiment of three independent experiments is shown. d NGF-differentiated PC-12 cells were treated with IL-20 (200 ng/ml), 7E (2 μg/ml), or IL-20 (200 ng/ml) plus 7E (2 μg/ml) for 6 h. Total RNA was isolated, and the transcripts of Sema3A, NRP-1, and NgR were analyzed using RT-qPCR with specific primers. GAPDH was an internal control. *P < 0.05 compared with the untreated controls (Ctrl). ^#P < 0.05 compared with IL-20-treated group. Data are expressed as mean ± SD and are representative of three independent experiments performed in quadruplicate