Washington University in St. Louis

The Patti Lab
Metabolomics to elucidate novel biochemical mechanisms of disease
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Isotope Tracing Untargeted Metabolomics Reveals Macrophage Polarization-State-Specific Metabolic Coordination across Intracellular Compartments

Puchalska P, Huang X, Martin SE, Han X, Patti GJ, and Crawford PA
Isotope Tracing Untargeted Metabolomics Reveals Macrophage Polarization-State-Specific Metabolic Coordination across Intracellular Compartments
iScience, 9, 298-313, 2018
doi:10.1016/j.isci.2018.10.029

We apply stable isotope tracing, mass-spectrometry-based untargeted metabolomics, to reveal thebiochemical space labeled by 13C-substrates in bone-marrow-derived macrophages. At the pathwaylevel, classically (lipopolysaccharide [LPS]-polarized, M1) and alternatively (interleukin [IL]-4-polar-ized, M2) polarized macrophages were 13C-labeled with surprising concordance. Total pools of uridinediphosphate N-acetylglucosamine (UDP-GlcNAc), an intermediate in the hexosamine biosyntheticpathway, were equally abundant in LPS- and IL-4-polarized macrophages. Informatic scrutiny of 13C-isotopologues revealed that LPS-polarized macrophages leverage the pentose phosphatepathway to generate UDP-GlcNAc, whereas IL-4-polarized macrophages rely on intact glucose andmitochondrial metabolism of glucose carbon. Labeling from [13C]glucose is competed by unlabeledfatty acids and acetoacetate, underscoring the broad roles for substrate metabolism beyond energyconversion. Finally, the LPS-polarized macrophage metabolite itaconate is imported into IL-4-polar-ized macrophages, in which it reprograms [13C]glucose metabolism. Thus, use of fully unsupervisedisotope tracing metabolomics in macrophages reveals polarization-state-specific metabolic pathwayconnectivity, substrate competition, and metabolite allocation among cellular compartments.

Washington University, Departments of Chemistry, Genetics, and Medicine. Saint Louis, Missouri 63110 USA