Jang Eun Jeong, Shin Yoonho, Park Hyen Joo, Kim Donghwa, Jung Cholomi, Hong Ji-Young, Kim Sanghee, Lee Sang Kook
College of Pharmacy, Natural Products Research Institute, Seoul National University, Seoul 151-742, Republic of Korea.
College of Pharmacy, Natural Products Research Institute, Seoul National University, Seoul 151-742, Republic of Korea.
J Dermatol Sci. 2017 Jul;87(1):19-28. doi: 10.1016/j.jdermsci.2017.03.011. Epub 2017 Mar 23.
Microphthalmia-associated transcription factor (MITF) suppresses the expression of enzymes controlling the production of melanin. Phytosphingosine is a well-known cosmetic agent, but its anti-melanogenic activity and mechanism of action remain unclear.
This study was designed to investigate the effects of phytosphingosine on melanin synthesis and elucidate the plausible mechanism of actions in vitro and ex vivo systems.
Melanin content, cell viability, tyrosinase activity, p-CREB DNA binding activity, and the protein gene expression levels of the enzymes and proteins involved in melanogenesis were measured with the treatment of phytosphingosine.
Phytosphingosine inhibits melanin synthesis in cultured melan-a cells and a reconstructed human skin model. One possible mechanism of the anti-melanogenic activity of phytosphingosine appears to be associated with the modulation of MITF, which suppresses the expression of tyrosinase, tyrosinase-related protein-1 (TRP-1), and TRP-2. Further analysis revealed that phytosphingosine suppressed paired box 3 and SRY-related HMG-box 10, critical transcription factors of MITF. Phytosphingosine also effectively downregulated the protein levels of β-catenin and the phospho-cAMP response element binding protein, an upstream regulatory factor of MITF. These results are closely related to the suppression of MITF gene expression. In addition, treatment with phytosphingosine for over 12h, which is a relatively long period of time, did not directly suppress these MITF transcriptional factors. Instead, phytosphingosine induced ERK activation, which led to MITF phosphorylation, followed by its degradation. Therefore, the downregulation of MITF protein levels by phytosphingosine with a long time exposure is in part associated with MITF protein degradation through the MAPK kinase activation pathway.
The modulation of MITF by phytosphingosine is closely related with the signaling pathways, such as the suppression of the MITF gene expression and the degradation of the MITF protein, depending on the duration of treatment time. These results suggest that phytosphingosine might serve as an effective melanogenesis inhibitor in melanocytes via the regulation of the MITF signaling pathways.
小眼畸形相关转录因子（MITF）可抑制控制黑色素生成的酶的表达。植物鞘氨醇是一种知名的化妆品原料，但其抗黑色素生成活性及作用机制尚不清楚。
本研究旨在探讨植物鞘氨醇对黑色素合成的影响，并阐明其在体外和离体系统中的可能作用机制。
通过植物鞘氨醇处理，测定黑色素含量、细胞活力、酪氨酸酶活性、p-CREB DNA结合活性以及参与黑色素生成的酶和蛋白质的蛋白基因表达水平。
植物鞘氨醇可抑制培养的黑色素-a细胞和重建的人皮肤模型中的黑色素合成。植物鞘氨醇抗黑色素生成活性的一种可能机制似乎与MITF的调节有关，MITF可抑制酪氨酸酶、酪氨酸酶相关蛋白-1（TRP-1）和TRP-2的表达。进一步分析表明，植物鞘氨醇可抑制配对盒3和SRY相关的高迁移率族盒10，这是MITF的关键转录因子。植物鞘氨醇还可有效下调β-连环蛋白的蛋白水平以及磷酸化的环磷酸腺苷反应元件结合蛋白，后者是MITF的上游调节因子。这些结果与MITF基因表达的抑制密切相关。此外，用植物鞘氨醇处理超过12小时，这是一段相对较长的时间，并未直接抑制这些MITF转录因子。相反，植物鞘氨醇诱导ERK激活，导致MITF磷酸化，随后降解。因此，长时间暴露的植物鞘氨醇对MITF蛋白水平的下调部分与通过MAPK激酶激活途径导致的MITF蛋白降解有关。
植物鞘氨醇对MITF的调节与信号通路密切相关，如根据处理时间的长短抑制MITF基因表达和降解MITF蛋白。这些结果表明，植物鞘氨醇可能通过调节MITF信号通路，作为黑色素细胞中一种有效的黑色素生成抑制剂。
