Understanding the Lipidomic Landscape in Niemann-Pick Disease, Type C by Mass Spectrometry

The work described herein demonstrates the use of mass spectrometry imaging (MSI) and liquid-chromatography-mass spectrometry (LC-MS) as tools to study lipid changes in a genetic neurodegenerative disease model. Chapter 1 introduces the fundamentals of mass spectrometry as a tool for detection and structural characterization of lipids. The chapter also introduces the use of mass spectrometry as an imaging tool of tissue sections and will act as the foundation for the bulk of the data in this work. The latter part of the chapter introduces Niemann-Pick Disease, type C (NPC1), a lysosomal storage disease that is the model used in these studies. A hallmark of NPC1 disease is progressive cerebellar degeneration. Thus, the focus of the projects included have a strong emphasis on cerebellar analysis. Chapter 2 describes the use of MSI to study lipid patterning and alterations in the cerebellum of the Npc1 null mouse at a symptomatic timepoint of 7-weeks of age. At the same time, an algorithm to generate consensus spectra from multiple imaging data sets is introduced. The use of a consensus spectra provides a representative mass spectrum for multiple technical and biological replicates to conduct streamlined analyses between two datasets. Chapter 3 extends the scope of the use of MSI looking at lipids at pre-symptomatic and pre-terminal timepoints to observe the spatial changes of the lipids over disease progression. In addition, newly found altered lipids that are observed are discussed, proposing a possible connection to apoptosis. Chapter 4 describes a liquid-chromatography study investigating lipid alterations in the cerebellum in depth without spatial mapping. Finally, Appendix A is a published work by the author under the mentorship of Dr. Timothy A. Keiderling. This work describes how the amino-acid sequence influences fibril formation after high temperature incubation and under low pH. Vibrational spectroscopy and transmission electron microscopy were used to characterize the macrostructures formed by these dodecapeptides.