National Center for Control and Evaluation of Medicines, Istituto Superiore di Sanità, 00161 Rome, Italy.
National Center for Rare Diseases, Istituto Superiore di Sanità, 00161 Rome, Italy.
Biomolecules. 2019 Jul 17;9(7):287. doi: 10.3390/biom9070287.
Cholesterol-enriched functional portions of plasma membranes, such as caveolae and rafts, were isolated from lungs of wild-type (WT) and caveolin-1 knockout (Cav-1 KO) mice within detergent resistant membranes (DRMs). To gain insight into their molecular composition we performed proteomic and lipid analysis on WT and Cav-1 KO-DRMs that showed predicted variations of proteomic profiles and negligible differences in lipid composition, while Langmuir monolayer technique and small and wide-angle X-ray scattering (SAXS-WAXS) were here originally introduced to study DRMs biophysical association state. Langmuir analysis of Cav-1 containing DRMs displayed an isotherm with a clear-cut feature, suggesting the coexistence of the liquid-ordered () phase typical of the raft structure, namely "cholesterol-rich phase," with a phase fully missing in Cav-1 KO that we named "caveolin-induced phase." Furthermore, while the sole lipid component of both WT and KO-DRMs showed qualitatively similar isotherm configuration, the reinsertion of recombinant Cav-1 into WT-DRMs lipids restored the WT-DRM pattern. X-ray diffraction results confirmed that Cav-1 causes the formation of a "caveolin-induced phase," as suggested by Langmuir experiments, allowing us to speculate about a possible structural model. These results show that the unique molecular link between Cav-1 and cholesterol can spur functional order in a lipid bilayer strictly derived from biological sources.
从野生型（WT）和 caveolin-1 敲除（Cav-1 KO）小鼠的肺中分离富含胆固醇的质膜功能部分，如 caveolae 和脂筏，在去污剂抗性膜（DRMs）中。为了深入了解它们的分子组成，我们对 WT 和 Cav-1 KO-DRMs 进行了蛋白质组学和脂质分析，结果表明蛋白质组学图谱存在预测变化，而脂质组成几乎没有差异，同时，我们最初在这里引入 Langmuir 单层技术和小角和广角 X 射线散射（SAXS-WAXS）来研究 DRMs 的生物物理缔合状态。含有 Cav-1 的 DRMs 的 Langmuir 分析显示出具有明显特征的等温线，表明存在典型脂筏结构的有序液体（）相“富含胆固醇相”与 Cav-1 KO 中完全缺失的相共存，我们将其命名为“caveolin-induced 相”。此外，虽然 WT 和 KO-DRMs 的唯一脂质成分的等温线配置定性相似，但重组 Cav-1 重新插入 WT-DRMs 脂质中恢复了 WT-DRM 模式。X 射线衍射结果证实，Cav-1 如 Langmuir 实验所建议的那样，导致“caveolin-induced 相”的形成，这使我们能够推测出一种可能的结构模型。这些结果表明，Cav-1 与胆固醇之间独特的分子联系可以在严格源自生物来源的脂质双层中激发功能有序性。
