An in Vivo Membrane Density Perturbation Strategy for Identification of Liver Sinusoidal Surface Proteome Accessible from the Vasculature

Liver sinusoidal endothelial cells (LSEC), the predominant nonparenchyma cells in liver, play critical roles in many important physiological and pathological processes by virtue of their unique location at the blood−tissue interface. To uncover the protein composition of LSEC plasma membrane (PM) comprehensively and give implications for the tissue microenvironment heterogeneity, we have developed an in vivo modified membrane density perturbation method for purification of the PM fraction. The proteins were separated and identified by SDS-PAGE combined with LC-MS/MS (GeLC-MS/MS). A total of 837 nonredundant proteins were identified, including a number of proteins previously reported to be localized to the PM of LSEC, as well as others not described. A diversity of membrane proteins involved in signaling, traffic, transporting and adhesion functions were identified. Our results demonstrated that the in vivo membrane density perturbation was an effective strategy to purify LSEC PM.

肝窦内皮细胞（LSEC），作为肝脏中主要的非实质细胞，凭借其在血液-组织界面独特的位置，在众多重要的生理和病理过程中发挥着至关重要的作用。为了全面揭示LSEC质膜（PM）的蛋白质组成，并针对组织微环境的异质性提供启示，我们开发了一种基于体内改良的膜密度扰动方法，用于纯化PM组分。通过SDS-PAGE结合LC-MS/MS（GeLC-MS/MS）技术对蛋白质进行分离和鉴定，共鉴定出837种非冗余蛋白，其中包括一些先前报道定位于LSEC质膜的蛋白质，以及尚未描述的其他蛋白。我们识别出多种参与信号传导、交通、运输和粘附功能的膜蛋白。研究结果证实，体内膜密度扰动是一种有效的纯化LSEC PM的策略。