Effects of Thioureas, Inhibitors of Melanogenesis, on Lens Transdifferentiation of Cultured Chicken Embryonic Retinal Pigment Cells. (retinal pigment cells/thioureas/transdifferentiation/cell culture)

Abstract

The effects of phenylthiourea (PTU) and its analogs on chick embryonic pigmented epithelial cells (PEC) in culture were studied to elucidate the correlation between inhibition of melanogenesis of PEC and enhancement of their transdifferentiation into lens cells. Both 0.25-0.5 mM PTU and 0.1 mM .alpha.-naphthylthiourea (ANTU) effectively inhibited melanogenesis of PEC and stimulated their transdifferentiation into lens cells at the same time. Thiourea (TU) also inhibited melanogenesis at a much higher concentration (4 mM) but did not stimulate the lens transdifferentiation at all. Methylthiourea (MTU) did not inhibit melanogenesis but stimulated the lens transdifferentiation. Testicular hyaluronidase effectively amplified the above-mentioned stimulating effects of thioureas without their altering optimum concentrations, although this enzyme itself never enhanced the lens transdifferentiation of PEC but suppressed their melanogenesis at a concentration of 100 U/ml medium, onward. The suppression of melanogenesis of PEC by PTU or its analogs apparently does not directly correlate with their transdifferentiation into lens cells. The possible mode of thiourea actions on the lens transdifferentiation of PEC cultured in vitro is discussed.