TGF-BETA LATENCY - BIOLOGICAL SIGNIFICANCE AND MECHANISMS OF ACTIVATION

Transforming growth factor (TGF-)beta is secreted as a latent complex in which the mature growth factor remains associated with its propepti de. In order to elicit a biological response, the cytokine must be rel eased from the latent complex, a process termed latent TGF-beta activa tion or TGF-beta formation. Although latent TGF-beta activation is a c ritical step in the regulation of its activity, little is known about the molecular mechanisms that lead to the production of active TGF-bet a. In this article, we present an overview of the data available on th is topic, and we propose a tentative model for the mechanism of TGF-be ta formation based upon the observations with different cell systems a nd on recent findings on the structure of the latent TGF-beta complex.