In vivo high-resolution magic angle spinning proton NMR spectroscopy of Drosophila melanogaster flies as a model system to investigate mitochondrial dysfunction in Drosophila GST2 mutants

In vivo nuclear magnetic resonance spectroscopy (NMR), a non-destructive biochemical tool used for investigating live organisms, has recently been performed in studies of the fruit fly Drosophila melanogaster, a useful model organism for investigating genetics and physiology. We used a novel high-resolution magic angle-spinning (HRMAS) NMR method to investigate live Drosophila GST2 mutants using a conventional 14.1-T NMR spectrometer equipped with an HRMAS probe. The results showed that, compared to wild-type (wt) controls, the GST2 mutants had a 48% greater (CH2)n lipid signal at 1.33 ppm, which is an insulin resistance biomarker in Drosophila skeletal muscle (P=0.0444). The mutants also had a 57% greater CH2C= lipid signal at 2.02 ppm (P=0.0276) and a 100% greater -CH=CH- signal at 5.33 ppm (P=0.0251). Since the -CH=CH- signal encompasses protons from ceramide, this latter difference is consistent with the hypothesis that the GST2 mutation is associated with insulin resistance and apoptosis. The findings of this study corroborate our previous results, support the hypothesis that the GST2 mutation is associated with insulin signaling and suggest that the IMCL level may be a biomarker of insulin resistance. Furthermore, direct links between GST2 mutation (the Drosophila ortholog of the GSTA4 gene in mammals) and insulin resistance, as suggested in this study, have not been made previously. These findings may thus be directly relevant to a wide range of metabolically disruptive conditions, such as trauma, aging and immune system deficiencies, that lead to increased susceptibility to infection.