Pinto Sandra N, Silva Liana C, Futerman Anthony H, Prieto Manuel
Institute of Nanoscience and Nanotechnology, Lisboa, Portugal.
Biochim Biophys Acta. 2011 Nov;1808(11):2753-60. doi: 10.1016/j.bbamem.2011.07.023. Epub 2011 Jul 30.
Ceramide is an important bioactive sphingolipid involved in a variety of biological processes. The mechanisms by which ceramide regulates biological events are not fully understood, but may involve alterations in the biophysical properties of membranes. We now examine the properties of ceramide with different acyl chains including long chain (C16- and C18-), very long chain (C24-) and unsaturated (C18:1- and C24:1-) ceramides, in phosphatidylcholine model membranes. Our results show that i) saturated ceramides have a stronger impact on the fluid membrane, increasing its order and promoting gel/fluid phase separation, while their unsaturated counterparts have a lower (C24:1-) or no (C18:1-) ability to form gel domains at 37°C; ii) differences between saturated species are smaller and are mainly related to the morphology and size of the gel domains, and iii) very long chain ceramides form tubular structures likely due to their ability to form interdigitated phases. These results suggest that generation of different ceramide species in cell membranes has a distinct biophysical impact with acyl chain saturation dictating membrane lateral organization, and chain asymmetry governing interdigitation and membrane morphology.
神经酰胺是一种重要的生物活性鞘脂，参与多种生物过程。神经酰胺调节生物事件的机制尚未完全明确，但可能涉及膜生物物理性质的改变。我们现在研究了在磷脂酰胆碱模型膜中，具有不同酰基链的神经酰胺的性质，包括长链（C16和C18）、超长链（C24）和不饱和（C18:1和C24:1）神经酰胺。我们的结果表明：i）饱和神经酰胺对流体膜有更强的影响，增加其有序性并促进凝胶/流体相分离，而其不饱和对应物在37°C时形成凝胶域的能力较低（C24:1）或没有（C18:1）；ii）饱和种类之间的差异较小，主要与凝胶域的形态和大小有关；iii）超长链神经酰胺可能由于其形成交错相的能力而形成管状结构。这些结果表明，细胞膜中不同神经酰胺种类的产生具有独特的生物物理影响，酰基链饱和度决定膜的侧向组织，链不对称性控制交错和膜形态。
