Figure 3.

IGF-1 enhances BMP7-mediated anabolism by a potent inhibitory effect on noggin expression. A, To measure the BMP7 mediated noggin upregulation in bovine NP cells, serum-starved NP cells were stimulated by 10, 50, and 100 ng/ml BMP7 for 24 hrs. And then expression level of noggin, natural BMP receptor antagonist, was measured by real-time PCR (upper) and western blotting (bottom). B, To examine whether noggin inhibits BMP7-meidated anabolic effect, serum-starved NP cells were stimulated by endogenous noggin (100 ng/ml), BMP7 (100 ng/ml), and cocktail of noggin and BMP7 for 24 hrs. And then mRNA induction level of aggrecan and transcriptional factor SOX9 were measured by real-time PCR. C, To measure the IGF-1 mediated noggin downregulation, serum-starved NP cells were cultivated with presence of 1, 10, 50, and 100 ng/ml IGF-1 for 24 hrs. And then expression of noggin was measured by real-time PCR (upper) and western blotting (bottom). D, To observe whether IGF-1 inhibits BMP7-mediated noggin induction in bovine disc cells, serum-starved NP cells were stimulated by IGF-1 (100 ng/ml), BMP7 (100 ng/ml), and cocktail of IGF-1 and BMP7 for 24 hrs. Analysis of variance was performed using StatView 5.0 software. P-values lower than 0.05 were considered significant. For independent experiments in triplicates were performed.