P300 regulates Melanophilin expression by modulating TFAP2A binding through histone acetylation

Background: Melanophilin is an effector protein that interacts with Rab27a and Myosin Va and regulates melanosome transport in melanocytes. Type 3 Griscelli syndrome, a mutation in Mlph gene, is characterized by partial pigment dilution, without any associated systemic problems. P300 plays roles in histone acetylation and changes chromatin state. There has been considerable interest in epigenetic regulation of melanocytes. However, epigenetic control of Mlph expression is still poorly understood. Objectives: We investigated the underlying mechanisms by which P300 controls Mlph expression by histone acetylation. Methods: siRNA transfection was performed to knock down gene expression. We used numerous methods, including western blotting, quantitative PCR (qPCR), co-immunoprecipitation (co-IP), and chromatin immunoprecipitation (ChIP), to identify the mechanisms of epigenetic regulation via P300. Results: Perinuclear aggregation of melanosome is induced and Mlph expression is decreased by knockdown of P300. In this process, TFAP2A acts as a transcription factor and regulates Mlph transcription. Knockdown of P300 decreased TFAP2A binding to intron region of Mlph and H3K27ac level and then finally reduced Mlph expression. Our study revealed that P300 facilitates an open chromatin state through acetylation of H3K27 and TFAP2A could regulate Mlph expression by binding to the intron 1 region of Mlph. Conclusion: Mlph expression is regulated by epigenetic regulation via P300 in melanocytes. These findings provide new insights into the epigenetic mechanism of melanosome transport.