Vitamin E (α-
tocopherol, VitE) was discovered as a nutrient essential to protect fetuses, but its molecular role in embryogenesis remains undefined. We hypothesize that the increased lipid peroxidation due to VitE deficiency drives a complex mechanism of overlapping biochemical pathways needed to maintain
glutathione (GSH) homeostasis that is dependent on
betaine and its methyl group donation. We assess
amino acids and
thiol changes that occur during embryogenesis [12, 24 and 48 h post fertilization (hpf)] in VitE-sufficient (E+) and deficient (E-) embryos using two separate, novel protocols to quantitate changes using UPLC-MS/MS. Using partial least squares discriminant analysis, we found that
betaine is a critical feature separating embryos by VitE status and is higher in E- embryos at all time points. Other important features include:
glutamic acid, increased in E- embryos at 12 hpf;
choline, decreased in E- embryos at 24 hpf; GSH, decreased in E- embryos at 48 hpf. By 48 hpf, GSH was significantly lower in E- embryos (P < 0.01), as were both
S-adenosylmethionine (SAM, P < 0.05) and
S-adenosylhomocysteine (SAH, P < 0.05), while
glutamic acid was increased (P < 0.01). Since GSH synthesis requires
cysteine (which was unchanged), these data suggest that both the conversion of
homocysteine and the uptake of
cystine via the Xc- exchanger are dysregulated. Our data clearly demonstrates the highly inter-related dependence of methyl donors (
choline,
betaine, SAM) and the
methionine cycle for maintenance of
thiol homeostasis. Additional quantitative flux studies are needed to clarify the quantitative importance of these routes.