The TGF-beta superfamily: a multitask signalling pathway for the animal kingdom

The TGF-β superfamily consists of numerous members, including TGF-β proper, bone morphogenetic proteins (BMP) and growth differentiation factors (GDF). All TGF-β are dimeric cytokines present a biological active carboxy terminal domain of 110–140 amino acids following proteolysis. Bone morphogenetic proteins (BMPs), first identified for their involvement in vertebrate bone formation, are now widely recognized as key factors in the regulation of many fundamental developmental processes in all deuterostomes. The active gradient established by BMP secreted ligands is one of the essential factors responsible for generating the positional information that underlies developmental patterning, including the regeneration of lost parts. Myostatin or GDF-8, a recently discovered GDF subfamily member, acts as a negative regulator in maintaining the mammalian proper muscle mass during both embryogenesis and post-natal muscle development. Unlike most other members of the BMP/GDF superfamily, mammalian myostatin is secreted as a latent complex, usually linked to regulatory proteins, and its mature dimer produces an effect almost exclusively on muscle tissue. The present chapter deals with the importance of the TGF-β family of growth factors in relation to regulatory spheres through the animal kingdom, focusing in particular on the expression of BMP molecules during regeneration and myostatin in “non-canonical” animal models; it also focuses on the regulative actions of myostatin during the development of vertebrates and in different experimental conditions, including in vitro chick co culture and endurance training. Data available in literature indicate that there is substantial scope for future research in the area of TGF-β /myostatin linked to development.