Transforming growth factor-beta 1 induces morphological changes accompanied by extracellular matrix reconstitution in cultures of avian retinal pigmented epithelial cells.

The mechanisms of cell differentiation have been extensively studied with an avian retinal pigmented epithelial cell (PEC) culture system. Transforming growth factor-beta (TGF-beta) has been reported to have stimulatory or inhibitory effects on differentiation depending on tissue type. Although the mechanism by which TGF-beta exerts diverse effects is unknown, changes in the extracellular matrix (ECM) are believed to be related to the effects of TGF-beta. Therefore, the effects of TGF-beta 1 on the cellular morphology and the distribution of ECM components such as laminin, tenascin, fibronectin, and types I and IV collagens were investigated in confluent cultures of differentiated PECs during a period of 6 days. We found that differentiated PECs with polygonal morphology and pigmented granules changed to pleomorphic and less pigmented cells 4 days after the addition of TGF-beta 1. These changes were preceded by changes in the distribution of ECM components, particularly laminin and tenascin after 2 days. The effects of TGF-beta on the differentiation of PECs are discussed.