Exploring the Structure and Dynamics of Ceramide Channels

知识价值。膜将细胞内部分隔开来，并将每个细胞与其环境分开。一般的教条是，蛋白质形成了特定分子在这些膜上转移的运输途径。然而，一种天然存在的脂质，神经酰胺，也被证明可以形成能够跨膜转运蛋白质的大通道。这与神经酰胺启动一种称为细胞凋亡的程序性细胞死亡的能力相吻合。这个过程的关键一步是从线粒体中释放蛋白质，很可能是通过神经酰胺通道。已知调节蛋白质释放的蛋白质（Bcl-2家族成员）也调节神经酰胺通道。提出的研究是了解蛋白质如何控制神经酰胺通道。由于许多证据表明神经酰胺通道是刚性结构，由氢键高度交联，一个可行的假设是，蛋白质与通道结合导致结构变化，这种变化波及整个结构，形成通道。这个和其他的假设将使用动力学和热力学方法以及微流体进行测试。此外，蛋白质和神经酰胺通道之间的相互作用将通过蛋白质突变和神经酰胺化学类似物的使用来探测。这些补充性的实验将深入了解蛋白质对脂质宏观结构的新调控，并将把对细胞生物学功能的生物物理和机制理解联系起来。这项研究也将增加我们对极其重要的细胞凋亡过程的理解。更广泛的影响：这项工作已经并将继续涉及高中、本科、研究生和博士后水平的学生培训。通常情况下，五到七名本科生（主修工程、化学或生物）和一名来自当地高中的暑期学生将与首席研究员密切合作。这项研究也对研究者的教学产生了很大的影响。他越来越认识到理解生物学基础物理学的重要性，这促使他倡导对本科生命科学专业的物理学教学进行彻底改变。作为试点项目，PI将继续教授一门名为“生命系统物理学”的荣誉课程，作为新物理课程的一部分，该课程将在项目期间扩大。

Intellectual merit. Membranes compartmentalize the cell interior and separate each cell from its environment. The general dogma is that proteins form the transport pathways by which specific molecules are translocated across these membranes. However, a naturally-occurring lipid, ceramide, has also been shown to form large channels capable of translocating proteins across membranes. This coincides with ability of ceramide to initiate a form of programmed cell death called apoptosis. A key step in this process is the release of proteins from mitochondria, likely through ceramide channels. Proteins known to regulate the protein release (members of the Bcl-2 family) also regulate ceramide channels. The proposed research is to understand how proteins control ceramide channels. Since much evidence suggests that ceramide channels are rigid structures, highly cross-linked by hydrogen bonding, a working hypothesis is that proteins bind to the channel causing a structural change that ripples through the entire structure to form the channel. This and other hypotheses will be tested using both kinetic and thermodynamics approaches and microfluidics. In addition, the interactions between the proteins and ceramide channels will be probed by mutations in the protein and the use of chemical analogs of ceramide. These complementary experiments will yield insights into the novel regulation of lipid macrostructures by proteins and will link biophysical and mechanistic understanding of cell biological function. This research will also add to our understanding of the extremely important cellular process of apoptosis.Broader impacts: The work has and will continue to involve the training of students at the high school, undergraduate, graduate, and post-doctoral levels. Typically five to seven undergraduates (majoring in engineering, chemistry or biology) and one summer student from a local high school will work closely with the principal investigator. The research has also greatly influenced the teaching of the investigator. His growing recognition of the importance of understanding the underlying physics of biology has led him to advocate for a radical change in the teaching of physics to undergraduate life science majors. As a pilot project, the PI will continue to teach an honors course entitled 'Physics of Living Systems' as part of a new physics curriculum, which will be expanded during the project period.