Fig 2: Dose-dependent changes in ZIP8 and MTF1 protein expression after IL-1ß stimulation in nucleus pulposus (NP) cells. Human NP cells were cultured for 72 hours in serum with different concentrations of IL-1ß. (A) ZIP8 protein expression changes with ß-actin normalization. (B) Nuclear MTF1 protein expression changes with PCNA normalization. Data are the mean ± standard deviation (SD) of triplicate results. **, P<0.01.

Fig 3: MTF1 is a target gene of miRNA-25-3p. (A) Schematic representation of the MTF 3'UTR showing the putative miRNA target site. (B) Luciferase activity of the MTF1 3'UTR reporter was analyzed in nucleus pulposus (NP) cells. An miRNA-25-3p mimic and its negative control (NC) were co-transfected with the wild-type MTF1 3'UTR or mutant vector. (C) The relative MTF1 mRNA and (D) protein expression of transfected NP cells with the miRNA-25-3p mimic and the NC were assessed using qRT-PCR and western blotting, respectively. ß-actin was used as an internal control. (E) Illustration depicting the IL-1ß/ZIP8/MTF1 signaling pathway regulatory mechanisms and miRNA-25-3p targets. Data are represented as the mean ± standard deviation (SD). *, P<0.05.