Effect of c-fos on aggrecan (Agg) and collagen type II (Col2) expression and cell proliferation in NP cells.

<p>(<b>A</b>) NP cells or stable AP-1 reporter cell were cotransfected with the Agg (400 ng) or Col2 (400 ng) reporter constructs and increasing concentrations of the WT-c-fos plasmid (100–500 ng), the DN-c-fos (100–500 ng) plasmid, or empty backbone. *<i>P</i> < 0.05 indicates differences between groups. Error bars represent the SD. (<b>B</b>) Detection of Agg protein expression by immunofluorescence microscopy. NP cells were cultured with (<b>a</b>) or without (<b>b</b>) WT-c-fos for 24 h, fixed, and stained with an antibody against Agg (green). Scale bar= 100 μm(C) Real-time-RT-PCR analysis of c-fos, Agg or Col2 expression in cells treated with vehicle (control) or a WT-c-fos expression plasmid. Total RNA was extracted from transfected cells and real-time RT-PCR was used to determine c-fos, Agg, Col2 and GAPDH RNA levels as an internal control. (<b>D</b>) The NP cells were treated with c-fos (1 ng/mL) in 96-well plates. Cell proliferation was evaluated using the MTT viability assay 12 or 24 h after treatment. n.s. = not significant.