Molecular dissection of organization and dynamics of lipid domains in biomembranes

(1)Lysenin是一种特异性结合鞘磷脂（SM）的致孔毒素。毒素与膜的结合伴随着蛋白质的寡聚化，导致孔形成。尽管先前的研究表明SM/胆固醇脂质体在抑制细胞裂解素诱导的溶血方面比SM脂质体有效10，000倍，但胆固醇的作用并不确切。我们的研究结果表明，胆固醇和SM/胞溶素的比例控制胞溶素单体的量，通过改变蛋白质寡聚化的状态，从而影响hemolysis.Duramycin是一种19个氨基酸的四环lantibiotic密切相关的肉桂霉素，这是已知的结合磷脂酰乙醇胺（PE）。未确定耐久霉素的脂质特异性。我们的研究表明，都duramycin和肉桂霉素专门结合乙醇胺磷脂的曲率依赖性的方式。(2)胆固醇对细胞内吞作用的调节当中国仓鼠卵巢（CHO）细胞达到融合时，细胞胆固醇增加。我们发现几种荧光脂质的内吞途径以细胞融合依赖的方式改变。细胞胆固醇在细胞融合依赖的内吞作用中起着至关重要的作用。我们的研究结果还表明，胆固醇控制胞吞途径的一个子集的膜脂通过rab 11。(3)内体脂质结构域对细胞内胆固醇稳态的调节利用D-磷酸二酯和神经节苷脂GM 1，显示富含双（单酰基甘油）磷酸（BMP）的晚期内体脂质结构域的结构改变在细胞胆固醇积累中起关键作用。我们还采用抗BMP单克隆抗体研究了BMP结构域在巨噬细胞胆固醇稳态中的作用。

(1) Characterization of lipid probesLysenin is a pore-forming toxin that specifically binds sphingomyelin (SM). The binding of the toxin to the membrane is accompanied by the oligomerization of the protein, leading to pore formation. Although a previous study showed that SM/cholesterol liposomes were 10,000 times more effective than SM liposomes in inhibiting lysenin-induced hemolysis, the role of cholesterol is not precisely clarified. Our results indicate that both cholesterol and the SM/lysenin ratio control the amount of lysenin monomer via altering the state of protein oligomerization, thus affecting hemolysis.Duramycin is a 19 amino acid tetracyclic lantibiotic closely related to cinnamycin, which is known to bind phosphatidyl-ethanolamine (PE). The lipid specificity of duramycin was not established. Our study indicates that both duramycin and cinnamycin exclusively bind to ethanolamine phospholipids in curvature-dependent manner.(2) Regulation of endocytosis by cholesterolCellular cholesterol increases when cells reach confluency in Chinese hamster ovary (CHO) cells. We showed that the endocytic pathways of several fluorescent lipids were altered in cell confluency-dependent manner. The crucial role of cellular cholesterol in cell-confluency dependent endocytosis was suggested. Our results also suggest that cholesterol controls endocytic routes of a subset of membrane lipids through rab11.(3) Regulation of cellular cholesterol homeostasis by endosome lipid domainsUsing D-PDMP and ganglioside GM1, it is shown that the structure alteration of bis (monoacylglycero) phosphate (BMP)-rich late endosome lipid domain plays a crucial role in cellular cholesterol accumulation. We also employed anti-BMP monoclonal antibody to examine the role of BMP domain in cholesterol homeostasis in macrophages.