Controlling mesenchymal stem cell differentiation by TGFBeta family members

Mesenchymal stem cells can differentiate into various tissue types including bone, cartilage, fat, and muscle. Transforming growth factor-Beta (TGFBeta) family members, including TGFBetas and bone morphogenetic proteins (BMPs), play important roles in directing fate decisions for mesenchymal stem cells. TGFBeta can provide competence for early stages of chondroblastic and osteoblastic differentiation, but it inhibits myogenesis, adipogenesis, and late-stage osteoblast differentiation. BMPs also inhibit adipogenesis and myogenesis, but they strongly promote osteoblast differentiation. TGFBeta family members signal via specific serine/threonine kinase receptors and their nuclear effectors, termed Smad proteins. In this review we discuss recent advances in our understanding of the molecular mechanisms by which TGFBeta family members control mesenchymal stem cell differentiation.