Epoxide hydrolase 3 (Ephx3) gene disruption reduces ceramide linoleate epoxide hydrolysis and impairs skin barrier function.
Epoxide hydrolase 3 (Ephx3) gene disruption reduces ceramide linoleate epoxide hydrolysis and impairs skin barrier function.
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DOI：
10.1074/jbc.ra120.016570
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发表时间：
2021-01
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影响因子：
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通讯作者：
Brash AR
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作者：
Edin ML;Yamanashi H;Boeglin WE;Graves JP;DeGraff LM;Lih FB;Zeldin DC;Brash AR
从体外实验中已知哺乳动物环氧化物水解酶 (EPHX)3 可有效地将亚油酸酯环氧化物 9,10-环氧十八碳烯酸 (EpOME) 和环氧醇 9R,10R-反式环氧-11E-13R-羟基十八碳烯酸酯分别水解为相应的二醇和三醇。在此，我们研究了 EPHX3 与体内两种底物水解的生理相关性。 Ephx3−/− 小鼠没有表现出 EpOME 衍生的血浆二醇缺乏，从而削弱了 EPHX3 在其形成中的作用，而表皮 12R-脂氧合酶途径的酰基神经酰胺中酯化的环氧醇衍生的三醇则减少。尽管Ephx3−/−幼鼠看起来正常，但与野生型或杂合子小鼠相比，经表皮水分流失的测量发现有适度且统计学上显着的增加，反映了皮肤屏障损伤，这在小鼠微粒体（EPHX1/微粒体环氧化物水解酶）或可溶性（EPHX2/sEH）敲除中并不明显。 Ephx3−/− 幼崽中的这种屏障表型与表皮中共价结合的神经酰胺的显着减少相关（减少 40%，p < 0.05），表明水屏障完整性相应的结构受损。对小鼠表皮中酯化亚油酸酯衍生三醇的定量 LC-MS 分析显示，主要三羟基异构体 9R,10S,13R-三羟基-11E-十八碳烯酸酯在 Ephx3−/− 表皮中显着且异构体特异性减少（~85%）。我们得出结论，EPHX3（而不是 EPHX1 或 EPHX2）催化酰基神经酰胺中酯化的 12R-LOX/eLOX3 衍生的环氧醇的水解，并且可能通过 SDR9C7 脱氢途径控制通过替代和关键代谢途径的通量。重要的是，我们的研究结果还确定了 EPHX3 在天然酯化环氧化物底物转化中的功能作用，表明其在其他组织中的潜在贡献。
The mammalian epoxide hydrolase (EPHX)3 is known from in vitro experiments to efficiently hydrolyze the linoleate epoxides 9,10-epoxyoctadecamonoenoic acid (EpOME) and epoxyalcohol 9R,10R-trans-epoxy-11E-13R-hydroxy-octadecenoate to corresponding diols and triols, respectively. Herein we examined the physiological relevance of EPHX3 to hydrolysis of both substrates in vivo. Ephx3−/− mice show no deficiency in EpOME-derived plasma diols, discounting a role for EPHX3 in their formation, whereas epoxyalcohol-derived triols esterified in acylceramides of the epidermal 12R-lipoxygenase pathway are reduced. Although the Ephx3−/− pups appear normal, measurements of transepidermal water loss detected a modest and statistically significant increase compared with the wild-type or heterozygote mice, reflecting a skin barrier impairment that was not evident in the knockouts of mouse microsomal (EPHX1/microsomal epoxide hydrolase) or soluble (EPHX2/sEH). This barrier phenotype in the Ephx3−/− pups was associated with a significant decrease in the covalently bound ceramides in the epidermis (40% reduction, p < 0.05), indicating a corresponding structural impairment in the integrity of the water barrier. Quantitative LC-MS analysis of the esterified linoleate-derived triols in the murine epidermis revealed a marked and isomer-specific reduction (∼85%) in the Ephx3−/− epidermis of the major trihydroxy isomer 9R,10S,13R-trihydroxy-11E-octadecenoate. We conclude that EPHX3 (and not EPHX1 or EPHX2) catalyzes hydrolysis of the 12R-LOX/eLOX3-derived epoxyalcohol esterified in acylceramide and may function to control flux through the alternative and crucial route of metabolism via the dehydrogenation pathway of SDR9C7. Importantly, our findings also identify a functional role for EPHX3 in transformation of a naturally esterified epoxide substrate, pointing to its potential contribution in other tissues.