Our current study using deuterium oxide probed stimulated Raman Scattering (DO-SRS) imaging provides new insights in brain lipid metabolism in female and male Drosophila individuals during aging processes. We found that the 3D volumetric distribution of newly synthesized lipids is heterogeneous, aged male and female flies have different metabolic activities in brain LDs, the glial LDs remain predominantly TAGs during aging, lipogenic diets improve brain functions by promoting lipid biosynthesis, and the IIS pathway mediates diets-regulated brain lipid metabolism.
We use D2O probed stimulated Raman scattering (DO-SRS) and multiphoton fluorescence (MPF) microscopy to visualize metabolic changes in cells and tissues during aging processes and diseases. We further developed deconvolution algorithm to enhance the spatial resolution to generate super resolution metabolic imaging. The cellular spatial distribution of de novo lipogenesis, protein synthesis, NADH, Flavin, unsaturated lipids, and cholesterol were all imaged and quantified with hyperspectral detection of various macromolecules as multiplex imaging. Our study shows that the integrated metabolic imaging and spectroscopy platform can be applied to study nutrition regulated metabolic dynamics in cancer and during aging processes.
We use D2O probed stimulated Raman scattering (DO-SRS) and Multiphoton Fluorescence (MPF) microscopy to visualize metabolic changes in HeLa cells under excess AAA of phenylalanine or tryptophan. The cellular spatial distribution of de novo lipogenesis, protein synthesis, NADH, Flavin, unsaturated lipids, and cholesterol were all imaged and quantified in this experiment. Our studies reveal the increase in NADH to Flavin ratio by 10% and unsaturated lipids to saturated by 50% in cells treated with excess phenylalanine and tryptophan. Our study shows that DO-SRS can be used to as a high resolution imaging platform to study AAA regulated metabolic activities in cells.
Emerging studies have shown that oxidative imbalance is critical in disease progression such as cancer and Alzheimer’s [1, 2]. This variation can lead to the upregulation of certain metabolic pathways inducing diseases and disorders. Aromatic amino acids (AAA) are involved with the production of Reactive Oxygen Species (ROS), resulting in the increase of oxidative stress [3]. AAA studies typically rely on gas chromatography (GC) or mass spectroscopy (MS)-based imaging techniques to study lipids; however, these methods lack the ability to show the cell’s lipid spatial distribution or require fluorescent dyes that can interfere with the cell’s molecular activities [4, 5]. Here, we established an optical imaging approach that combines D2O (heavy water) probed Stimulated Raman scattering (DO-SRS) and Multiphoton Fluorescence (MPF) microscopy to directly visualize metabolic activities in situ in cancer cells under the regulation of excess AAA, specifically Phenylalanine and Tryptophan. The cellular spatial distribution of de novo lipogenesis, unsaturated and saturated lipids, NADH, Flavin, and new protein synthesis were quantitatively imaged and examined. We discovered an increase in de novo lipogenesis, Flavin/(Flavin + NADH), and unsaturated to saturated lipids in the cancer cells treated with excess AAAs. Decrease of protein turnover rate occurred in the same treated cells with observations of higher lipid droplet content. These observed metabolic activities are signs of mitochondrial dysfunction and oxidative stress. Our study demonstrates that DO-SRS can be used as a high-resolution imaging platform to study AAA regulated metabolic activities in cells and elucidates the linkage between lipid metabolism and cancer.
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