Transforming growth factor-ßs as modulators of pericellular proteolytic events.

Since the discovery of transforming growth factor-ß:s an increasing number of different biological effects have been attributed to this group of proteins. Analysis of the cellular responses to TGFß stimulation at the molecular level has indicated that TGFß acts as an activator of transcription of several genes. This may in part explain the plethora of various functions that have been ascribed to TGFß. In addition to the TGFß family of polypeptides there is an increasing number of related factors, whose major roles appear to be involved in developmental processes. A distinct feature of TGFß is its ability to regulate pericellular proteolysis of cultured cells. As yet this property has not been associated with other members of this group of polypeptides. Depending on the target cell type TGFß may either increase or decrease pericellular proteolytic activity. Proteolytic activation of latent TGFß and its possible inhibition by TGFß-induced protease inhibitors could be a physiological feed-back mechanism in the control of proteolytic activity in the vicinity of cells.