Choi Hyun Kyung, Kim Hyun-Ji, Liu Kwang-Hyeon, Park Chang Seo
Department of Chemical Engineering, Dongguk University, 3-26, Pil-dong, Chung-gu, Seoul, 100-715, Republic of Korea.
BK21 Plus Multi-Omics based Creative Drug Research Team, College of Pharmacy and Research Institute of Pharmaceutical Sciences, Kyungpook National University, 80, Daehak-ro, Buk-gu, Daegu, 41566, Republic of Korea.
Lipids. 2018 Sep;53(9):909-918. doi: 10.1002/lipd.12097.
Ceramide NP is known to be the most abundant class of 12 ceramide (CER) families that form a permeability barrier in the human skin barrier. However, not many studies have been reported on the regulation of the biosynthesis of ceramide NP. Recently, it has been reported that phytosphingosine (PHS) treatment in the cultured keratinocytes (KC) notably increased the content of ceramide NP. However, the mechanism behind the PHS-induced enhancement of ceramide NP has not been elucidated. In this study, we investigated the effects of PHS on the expression of several essential genes for the biosynthesis of CER. Also, we determined the molecular mechanism behind the unique enhancement of ceramide NP upon treatment of PHS in the cultured KC. The expressions of all of the three genes (SPT, ceramide synthase 3 [CERS3], and ELOVL4) and their respective proteins were markedly increased in PHS-treated KC. In addition, the expression of the dihydroceramide C4-desaturase (DES2) responsible for conversion of dihydroceramide into ceramide NP was uniquely enhanced only by PHS treatment. Liquid chromatography-tandem mass spectrometry (LC-MS/MS) analysis revealed that more than 20-fold increase of ceramide NP by PHS was observed while no significant enhancement of ceramide NS and NDS was observed. This study demonstrates that PHS plays a fundamental role in strengthening the epidermal permeability barrier by stimulating the overall processes of biosynthesis of all classes of CER in epidermis. The dramatic increase of ceramide NP upon PHS treatment seemed to be the outcome of transformation of dihydroceramide and/or ceramide NS by C4-hydroxylase activity.
神经酰胺NP是已知的12种神经酰胺（CER）家族中含量最丰富的一类，在人体皮肤屏障中形成渗透屏障。然而，关于神经酰胺NP生物合成调控的研究报道并不多。最近，有报道称在培养的角质形成细胞（KC）中进行植物鞘氨醇（PHS）处理可显著增加神经酰胺NP的含量。然而，PHS诱导神经酰胺NP增加的背后机制尚未阐明。在本研究中，我们研究了PHS对CER生物合成几个关键基因表达的影响。此外，我们确定了在培养的KC中用PHS处理后神经酰胺NP独特增加背后的分子机制。在PHS处理的KC中，所有三个基因（丝氨酸棕榈酰转移酶[SPT]、神经酰胺合酶3[CERS3]和脂肪酸延长酶4[ELOVL4]）及其各自蛋白质的表达均显著增加。此外，负责将二氢神经酰胺转化为神经酰胺NP的二氢神经酰胺C4-去饱和酶（DES2）的表达仅通过PHS处理得到独特增强。液相色谱-串联质谱（LC-MS/MS）分析显示，PHS处理使神经酰胺NP增加了20多倍，而神经酰胺NS和NDS未观察到显著增强。本研究表明，PHS通过刺激表皮中所有类型CER生物合成的整体过程，在加强表皮渗透屏障方面发挥着重要作用。PHS处理后神经酰胺NP的显著增加似乎是二氢神经酰胺和/或神经酰胺NS通过C4-羟化酶活性转化的结果。
