Purpose: MITF is a transcription factor. It is responsible for pigmented cell-specific transcription of melanogenic enzyme genes and regulates differentiation and development of retinal pigment epithelium. Melanogenic enzymes TYR and DCT control two critical steps of melanogenesis, and OTX2 can trans-activate both genes’ promoters. This study has considered passage number-dependent changes in gene expression of MITF-A, MITF-H, OTX2, TYR and DCT. Methods: RPE cells were isolated from neonatal human globes and cultured in DMEM: F12 (1:1) supplemented with 10% FBS. When cultures in passages 1-7 reached to 90% confluency, RNA was extracted and reversely transcribed using Qiagen cDNA synthesis kit and subjected to amplification by Real-Time PCR. Results: According to Real-Time RT-PCR results, increasing in passage number of RPE cultures, culminated to decreased transcription rate of MITF-H, TYR, DCT and OTX2. Conclusion: According to the roles of TYR and DCT in melanogenesis, decrease in their gene expression will reduce melanin content in RPE cells, furthermore reduction in gene expression of MITF-H and OTX2 as transcription factors will affect other molecules and transcription factors that will influence proliferation, differentiation and conventional mechanisms of RPE cells.

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