Chiantia Salvatore, Kahya Nicoletta, Schwille Petra
Biophysics group, Biotechnologisches Zentrum (BIOTEC), Technische Universität, Tatzberg 47-51, 01307, Dresden, Germany.
Langmuir. 2007 Jul 3;23(14):7659-65. doi: 10.1021/la7010919. Epub 2007 Jun 12.
Naturally occurring long-chain ceramides (Cer) are known to alter the lateral organization of biological membranes. In particular, they produce alterations of microdomains that are involved in several cellular processes, ranging from apoptosis to immune response. In order to induce similar biological effects, short-chain Cer are extensively used in in vivo experiments to replace their long-chain analogues. In this work, we used the combined approach of atomic force microscopy (AFM) and fluorescence correlation spectroscopy (FCS) to investigate the effect of Cer chain length in lipid bilayers composed of sphingomyelin, dioleoyl-phosphatidylcholine, and cholesterol. Our results show that only long-chain Cer, like C18 and C16, are able to segregate from the liquid-ordered phase, forming separate Cer-enriched domains. Conversely, short-chain Cer do not form a separate phase but alter the physical properties of the liquid-ordered domains, decreasing their stability and viscosity and perturbing the lipid packing. These differences may contribute to the explanation of the different physiological effects that are often observed for the long- and short-chain Cer.
天然存在的长链神经酰胺（Cer）已知会改变生物膜的侧向组织。特别是，它们会导致微结构域发生改变，这些微结构域参与了从细胞凋亡到免疫反应等多种细胞过程。为了诱导类似的生物学效应，短链Cer被广泛用于体内实验以替代其长链类似物。在这项工作中，我们使用原子力显微镜（AFM）和荧光相关光谱（FCS）的联合方法，来研究Cer链长对由鞘磷脂、二油酰磷脂酰胆碱和胆固醇组成的脂质双层的影响。我们的结果表明，只有像C18和C16这样的长链Cer能够从液晶相分离出来，形成单独的富含Cer的结构域。相反，短链Cer不会形成单独的相，但会改变液晶结构域的物理性质，降低其稳定性和粘度，并扰乱脂质堆积。这些差异可能有助于解释长链和短链Cer经常观察到的不同生理效应。
