• retinal pigment epithelial cell, retinoic acid, TGF-β, proliferation, melanin synthesis

The purpose of this study was to investigate the effects of all-trans retinoic acid (RA) on the induction of transforming growth factor-β (TGF-β) that is concerned with the proliferation and melanin synthesis of chick retinal pigment epithelial (RPE) cells in vitro. Chick RPE cells were cultured in the presence or absence of RA and anti-TGF-β antibody for 7 days. The effects of RA and pan-specific TGF-β antibody on RPE cell proliferation were assessed by counting the number of cells, and their effects on melanin synthesis were evaluated by measuring the melanin content of the cells. TGF-β activity in the culture supernatant of RPE cells was measured using CCL-64 cells. RA significantly inhibited RPE cell proliferation and increased melanin synthesis. The addition of pan-specific TGF-β antibody to the culture blocked the inhibition of RPE cell proliferation and the increased melanin synthesis. RA induced TGF-β production in the culture supernatant of RPE cells. These findings indicate that RA regulates the proliferation and melanin synthesis of RPE cells via induction of TGF-β.