Leptin-induced BMP-2 mRNA expression is mediated by JAK2-ERK1/2 signaling in human primary chondrocytes.

(A) Cells were kept as controls or treated with leptin for 10’, 30’, 1, 4, and 8 h, and the phosphorylations of JAK1/2 and ERK1/2 were determined by Western blot. (B-D) Cells were transfected with (B-C) JAK1- or JAK2-specific siRNA or (D) ERK1- or ERK2-specific siRNA and then kept as controls or treated with leptin for 4 h. (B) The phosphorylation of ERK1/2 was determined by Western blot and (C-D) the BMP-2 mRNA expression was determined by real-time PCR. Results in (A) and (B) are representative of three independent experiments with similar results. Data in (C) and (D) are mean ± SEM from three independent experiments. *, P vs. siCL/control or untreated cells. #, P vs. siCL/leptin-treated cells.