Fig. 7
From: Osteoarthritis: pathogenic signaling pathways and therapeutic targets
Schematic representation of TGFβ/BMP signaling pathway in OA chondrocytes. TGF-β/BMP family ligands bind to type I and type II receptors on the cell surface. TGF-βs bind TGFβRI and TGFβRII, and BMPs bind BMPRI and BMPRII. TGFβRIII is a coreceptor that facilitates interaction with TβRI and TβRII. TGF-βs induce the phosphorylation of Smad2/3, and BMPs mediate Smad1/5/8 phosphorylation. By forming complexes with Smad4, phosphorylated Smad2/3 and Smad1/5/8 translocate into the nucleus to regulate target gene expression
