Schematic diagram of the glutamine:fructose-6-phosphate amidotransferase 1
(GFPT1)–mediated MTOR signaling pathway affected by glucose and
fructose in porcine trophectoderm cells. Available evidence from our study
indicates that fructose and glucose are metabolized via GFPT1 in the
hexosamine biosysthesis pathway and activate mTOR-RPS6K and mTOR-EIF4EBP1
signal transduction cascades for porcine trophoblast cell proliferation and
mRNA translation, as well as synthesis of glycosaminoglycans such as
hyaluronic acid. Fru, fructose; Glc, glucose; GLUT, glucose/fructose
transporter; Glc-6P, glucose-6-phosphate; Fru-1P, fructose-1-phosphate;
Fru-6P; GlcN-6P, N-acetylglucosamine-6-phosphate;
UDP-GlcNAC, UDP-N-acetylglucosamine; GFPT1, glutamine-fructose-6-phosphate
transaminase 1; TSC2, tuberous sclerosis 2; mTOR, mechanistic target of
rapamycin; RPS6K, ribosomal protein S6K; RPS6, ribosomal protein S6;
EIF4EBP1, eukaryotic translation initiation factor 4E-binding protein 1;
AKT1, protooncogenic protein kinase Akt; MAPK/ERK, mitogen-activated protein
kinase/extracellular signal-regulated kinase.