Transforming growth factor-β1 induces type II collagen and aggrecan expression via activation of extracellular signal-regulated kinase 1/2 and Smad2/3 signaling pathways.

Transforming growth factor (TGF)‑β regulates the anabolic metabolism of articular cartilage and prevents cartilage degradation. TGF‑β1 influences cellular proliferation, differentiation and the extracellular matrix through activation of the extracellular signal‑regulated kinase (ERK)1/2 and Smad2/3 signaling pathways. However, it has remained to be fully elucidated precisely how the ERK1/2 and Smad2/3 signaling pathways mediate anabolic processes of articular cartilage.

Interaction of ERK1/2 and Smad2/3 signaling pathways in TGF-β1-induced TIMP-3 expression in rat chondrocytes.

Tissue inhibitor of metalloproteinase-3 (TIMP-3) is an important natural inhibitor of matrix metalloproteinases (MMPs) and of a disintegrin and metalloproteinase with thrombospondin motif (ADAMTs), which can cleave cartilage extracellular matrix components to cause cartilage degradation. In this study, our data suggest TGF-β1 induces TIMP-3 expression through activations of both the ERK1/2 and Smad2/3 signaling pathways. TGF-β1-stimulated TIMP-3 expression was significantly inhibited by SB525334 (TGF-β receptor I kinase inhibitor), accompanied by a reduction in ERK1/2 and Smad3 phosphorylation.