AGING, BRAIN MEMBRANE CHOLESTEROL DOMAINS AND CALCIUM

这项拨款申请的总体目标是研究潜在的 与调节神经元跨双层和外侧 胆固醇结构域以及胆固醇结构域如何与钙相互作用 不同年龄组小鼠神经元膜的动态平衡。我们有 最近在年轻C57 BL小鼠的突触质膜（SPM）中显示， 两个膜小叶的流动性是不对称的， 胆固醇分布膜胆固醇也被发现是 位于可交换和不可交换池和膜中 胆固醇结构域可以通过鞘磷脂的水解而改变， 也改变了细胞内的钙。来自我们实验室的初步数据 表明两个SPM小叶之间的流动性不对称， 在6个月大的动物中观察到的28 月龄的动物，外面小叶受到的影响更大， 与细胞面小叶相比。膜脂的研究进展 不同年龄组动物的结构已经检查了 膜脂质结构的平均流动性，而其他研究 没有观察到年龄差异。我们认为，年龄的增长是 与膜脂质结构的显著变化有关， 改变发生在特定的脂质结构域和脂质结构域的变化。 结构域有助于改变钙稳态， 以前显示随着年龄的增长而不同。拟议的实验 将重点研究4、16和28个月龄C57 BL/NNia的SPM和突触体 小鼠本申请的具体目的是：1）确定 胆固醇在SPM外表面的跨双层分布， 细胞面小叶; 2）检查SPM中的胆固醇侧域; 3） SPM外表面和细胞表面小叶中的磷脂分布; 4） 鞘磷脂参与胆固醇结构域的调节; 5） 脑固醇载体蛋白和胆固醇结构域的调节;以及 6)胆固醇结构域和突触前钙。这是我们的工作 衰老损害膜调节能力的假说 胆固醇结构域和胆固醇结构域中的这种变化修饰 神经元钙

The overall goals of this grant application are to study potential mechanisms associated with regulation of neuronal transbilayer and lateral cholesterol domains and how cholesterol domains interact with calcium homeostasis in neuronal membranes of different age groups of mice. We have recently shown in synaptic plasma membranes (SPM) of young C57BL mice, that the two membrane leaflets are asymmetric in their fluidity and cholesterol distribution. Membrane cholesterol was also found to be located in exchangeable and non-exchangeable pools and membrane cholesterol domains could be altered by hydrolysis of sphingomyelin that also altered intracellular calcium. Preliminary data from out laboratory showed that the asymmetry of fluidity between the two SPM leaflets observed in 6 month old animals was significantly reduced in SPM of 28 month old animals and that the exofacial leaflet was more affected as compared to the cytofacial leaflet. Previous studies on membrane lipid structure in different age groups of animals have examined changes in the average fluidity of the membrane lipid structure, whereas other studies have not observed age differences. We propose that increasing age is associated with marked changes in membrane lipid structure but that such changes are occurring in specific lipid domains and changes in lipid domains contribute to modification of calcium homeostasis that has been previously shown to differ with increasing age. The proposed experiments will focus on SPM and synaptosomes of 4, 16, and 28 month old C57BL/NNia mice. The specific aims of this application are to: 1) determine transbilayer distribution of cholesterol in the SPM exofacial and cytofacial leaflets; 2) examine cholesterol lateral domains in SPM; 3) phospholipid distribution in SPM exofacial and cytofacial leaflets; 4) involvement of sphingomyelin in regulation of cholesterol domains; 5) brain sterol carrier proteins and regulation of cholesterol domains; and 6) cholesterol domains and presynaptic calcium. It is our working hypothesis that aging impairs the capacity of the membrane to regulate cholesterol domains and such changes in cholesterol domains modify neuronal calcium.