Coomans de Brachène Alexandra, Dif Nicolas, de Rocca Serra Audrey, Bonnineau Chloé, Velghe Amélie I, Larondelle Yvan, Tyteca Donatienne, Demoulin Jean-Baptiste
de Duve Institute MEXP unit Université catholique de Louvain Brussels Belgium.
Institute of Life Sciences Université catholique de Louvain Louvain-La-Neuve Belgium.
FEBS Open Bio. 2017 Feb 2;7(3):414-423. doi: 10.1002/2211-5463.12194. eCollection 2017 Mar.
Stearoyl-coenzyme A desaturase (SCD) catalyzes the Δ9-cis desaturation of saturated fatty acids (SFA) to generate monounsaturated fatty acids (MUFA). This enzyme is highly up-regulated by platelet-derived growth factor (PDGF) in human fibroblasts. Accordingly, the analysis of cellular fatty acids by gas chromatography showed that PDGF significantly increased the proportion of MUFA, particularly palmitoleate, in cellular lipids. To further analyze the role of SCD in fibroblasts, we used small hairpin RNA targeting SCD (shSCD), which decreased the MUFA content. SCD down-regulation blunted the proliferation of fibroblasts in response to PDGF. This was confirmed using a pharmacological inhibitor of SCD. In addition, proliferation was blocked by palmitate and stearate (two SCD substrates) but not by palmitoleate and oleate (two SCD products). In the presence of an equal amount of oleate, palmitate had no effect on cell proliferation. SCD inhibition or down-regulation did not decrease PDGF receptor activity or signaling. However, by measuring plasma membrane lipid lateral diffusion by fluorescence recovery after photobleaching, we showed that the modulation of the MUFA/SFA ratio by PDGF and SCD inhibitor was related to modifications of membrane fluidity. Altogether, our data suggest that SCD is required for the response of normal fibroblasts to growth factors.
硬脂酰辅酶A去饱和酶（SCD）催化饱和脂肪酸（SFA）的Δ9-顺式去饱和反应，生成单不饱和脂肪酸（MUFA）。在人成纤维细胞中，该酶受血小板衍生生长因子（PDGF）的高度上调。因此，通过气相色谱法对细胞脂肪酸进行分析表明，PDGF显著增加了细胞脂质中MUFA的比例，尤其是棕榈油酸酯。为了进一步分析SCD在成纤维细胞中的作用，我们使用了靶向SCD的小发夹RNA（shSCD），其降低了MUFA含量。SCD下调减弱了成纤维细胞对PDGF的增殖反应。使用SCD的药理学抑制剂证实了这一点。此外，增殖被棕榈酸酯和硬脂酸（两种SCD底物）阻断，但未被棕榈油酸酯和油酸（两种SCD产物）阻断。在存在等量油酸的情况下，棕榈酸酯对细胞增殖没有影响。SCD抑制或下调并未降低PDGF受体活性或信号传导。然而，通过光漂白后荧光恢复测量质膜脂质侧向扩散，我们表明PDGF和SCD抑制剂对MUFA/SFA比值的调节与膜流动性的改变有关。总之，我们的数据表明SCD是正常成纤维细胞对生长因子作出反应所必需的。
