Cho Y, Ziboh V A
Department of Dermatology, University of California, Davis 95616.
J Lipid Res. 1994 Feb;35(2):255-62.
Ceramides and phospholipids constitute two important structural lipids of normal skin that are notably rich in polyunsaturated fatty acids. Although linoleic acid (LA) is high in the ceramides, the localization of its 15-lipoxygenase product, 13-hydroxyoctadecadienoic acid (13-HODE) in the epidermis is unknown. In this study, we investigated the relative incorporation of [14C]LA and [14C]13-HODE into ceramides and phospholipids in isolated epidermal slices. Our data revealed minor incorporation of [14C]LA and [14C]13-HODE into ceramides. In contrast, both [14C]LA and [14C]13-HODE are markedly incorporated into phospholipids, particularly, phosphatidylcholine (PC) and phosphatidylinositol (PtdIns). The incorporation of 13-HODE into the PtdIns pool in particular prompted us to investigate into its fate in the signal transduction process and its possible incorporation into diacylglycerol. Our data revealed that 13-HODE is incorporated into epidermal phosphatidylinositol 4,5-bisphosphate (PtdIns4,5-P2) resulting in epidermal phospholipase C-catalyzed release into a novel 13-HODE-containing diacylglycerol (1-acyl-2-13-HODE-glycerol). The possibility now exists that this novel 13-HODE-containing diacylglycerol could function to modulate the activity of epidermal protein kinase C and hyperproliferation/differentiation.
神经酰胺和磷脂是正常皮肤中两种重要的结构脂质，富含多不饱和脂肪酸。虽然亚油酸（LA）在神经酰胺中含量很高，但其15-脂氧合酶产物13-羟基十八碳二烯酸（13-HODE）在表皮中的定位尚不清楚。在本研究中，我们研究了[14C]LA和[14C]13-HODE在分离的表皮切片中相对掺入神经酰胺和磷脂的情况。我们的数据显示[14C]LA和[14C]13-HODE少量掺入神经酰胺。相反，[14C]LA和[14C]13-HODE都显著掺入磷脂，特别是磷脂酰胆碱（PC）和磷脂酰肌醇（PtdIns）。13-HODE尤其大量掺入PtdIns库，这促使我们研究其在信号转导过程中的去向以及其可能掺入二酰基甘油的情况。我们的数据显示，13-HODE掺入表皮磷脂酰肌醇4,5-二磷酸（PtdIns4,5-P2），导致表皮磷脂酶C催化释放到一种新型的含13-HODE的二酰基甘油（1-酰基-2-13-HODE-甘油）中。现在存在这样一种可能性，即这种新型的含13-HODE的二酰基甘油可能起到调节表皮蛋白激酶C活性以及过度增殖/分化的作用。
