Floating mitochondrial membrane mimics for investigating apoptosis regulating protein interactions

Mitochondrial apoptosis is a programmed suicide mechanism in cells essential for life. Upon oxidative stress, the mitochondrial outer membrane (MOM) undergoes permeabilization, followed by the release of apoptotic factors. This process is tightly regulated by the Bcl-2 protein family at the MOM. In healthy cells, the soluble, pro-apoptitic Bax is neutralized by the anti-apoptotic Bcl-2 embedded in the MOM, but any imbalance in this interaction can cause disorders including cancer. We are using neutron reflectometry to elucidate the function of the Bcl-2 protein family in supported lipid bilayers. In this experiment we will self-assemble floating bilayers from lipid extracts purified from yeast cells that match the human MOM composition closely, to investigate the pore-formation mechanism of Bax and role of cardiolipin in more realistic mimics of the MOM with an aqueous reservoir on both sides as in mitochondria.

线粒体细胞凋亡（Mitochondrial Apoptosis）是细胞内一类对生命活动至关重要的程序性死亡机制。当细胞遭遇氧化应激时，线粒体外膜（Mitochondrial Outer Membrane，MOM）会发生透化，随后释放各类凋亡因子。该过程在线粒体外膜处受到Bcl-2蛋白家族（Bcl-2 Protein Family）的严格调控。在健康细胞中，可溶性促凋亡蛋白Bax会被嵌入线粒体外膜的抗凋亡Bcl-2蛋白中和，但二者相互作用的任何失衡都可能引发包括癌症在内的多种疾病。本研究采用中子反射法（Neutron Reflectometry）阐释Bcl-2蛋白家族在支撑磷脂双层膜（Supported Lipid Bilayers）中的功能。本次实验将从酵母细胞（Yeast Cells）中纯化得到脂质提取物（Lipid Extracts），以此自组装得到组成与人类线粒体外膜高度匹配的浮动双层膜（Floating Bilayers），进而在双侧带有线粒体样水相储库（Aqueous Reservoir）的更贴近生理状态的线粒体外膜模拟体系中，探究Bax的孔形成机制以及心磷脂（Cardiolipin）所发挥的作用。