Changes in Cholesterol Level Alter Integrin Sequestration in Raft-Mimicking Lipid Mixtures
Changes in Cholesterol Level Alter Integrin Sequestration in Raft-Mimicking Lipid Mixtures
复制标题
DOI：
10.1016/j.bpj.2017.11.005
复制
发表时间：
2018-01-09
影响因子：
3.4
通讯作者：
Naumann, Christoph A.
中科院分区：
文献类型：
--
作者：
Ge, Yifan;Gao, Jiayun;Naumann, Christoph A.
采用互补、单分子灵敏、共聚焦检测方法，研究了胆固醇(Chol)水平对类RAFT类脂混合物中整合素固存的影响，形成了同时存在的液体有序(L(O))和液体无序(L(D))类脂结构域。对模型膜环境中膜蛋白分布的系统分析表明，胆固醇水平的变化对整合素的L(O)-L(D)的截留有深刻的影响，从而在没有配体的情况下表现出整体的L(D)偏好和L(O)对玻璃连结素加成的亲和力。对不同模型膜混合物中整合素的光子计数直方图分析表明，随着膜Chol水平的变化而观察到的整合素截留的变化与整合素齐聚状态的改变无关。相反，我们的实验表明，整合素封存对Chol的强烈依赖可以归因于Chol介导的L(O)和L(D)结构域中脂质堆积和双层厚度的变化，这突显了Chol介导调节整合素封存的生物物理机制的重要性。我们预计，这一膜模型研究可能有助于阐明Chol对质膜整合素功能的影响，从而进一步深入了解脂质异质性在细胞膜环境中膜蛋白分布和功能中的作用。
The influence of cholesterol (CHOL) level on integrin sequestration in raft-mimicking lipid mixtures forming coexisting liquid-ordered (l(o)) and liquid-disordered (l(d)) lipid domains is investigated using complementary, single-molecule-sensitive, confocal detection methods. Systematic analysis of membrane protein distribution in such a model membrane environment demonstrates that variation of CHOL level has a profound influence on l(o)-l(d) sequestration of integrins, thereby exhibiting overall l(d) preference in the absence of ligands and l(o) affinity upon vitronectin addition. Accompanying photon-counting histogram analysis of integrins in the different model membrane mixtures shows that the observed changes of integrin sequestration in response to variations of membrane CHOL level are not associated with altering integrin oligomerization states. Instead, our experiments suggest that the strong CHOL dependence of integrin sequestration can be attributed to CHOL-mediated changes of lipid packing and bilayer thickness in coexisting l(o) and l(d) domains, highlighting the significance of a biophysical mechanism of CHOL-mediated regulation of integrin sequestration. We envision that this model membrane study may help clarify the influence of CHOL in integrin functionality in plasma membranes, thus providing further insight into the role of lipid heterogeneities in membrane protein distribution and function in a cellular membrane environment.