Phosphoproteomic insights into GFPT2-Associated cellular phospho-signaling networks

The GFPT2 protein, also known as glutamine-fructose-6-phosphate aminotransferase 2, regulates glucose flux through the hexosamine biosynthesis pathway (HBP). It is primarily expressed in the spinal cord and central nervous system and is notably abundant in various cancers while being dysregulated in diabetes. Despite its significant role in critical diseases, the phospho-regulatory mechanisms governing GFPT2 function remain largely unexplored. To investigate the phospho-signaling networks of GFPT2, an analysis of the global phosphoproteomes examining GFPT2 phosphorylation sites (PS) across diverse experimental conditions was conducted. By compiling 448 qualitative and 74 quantitative differential cellular phosphoproteome datasets, a key phosphorylation site, S244, was identified in GFPT2, appearing in approximately 81 % of these datasets. Surprisingly, the functional significance of this phosphosite had not been studied or reported. A targeted strategy was employed to identify PS in proteins whose expression coregulated with the primary GFPT2 phosphorylation site. Subsequent functional analysis of these coregulated proteins revealed associations with neuronal disorders. Classification of coregulated phosphosites in proteins as known and predicted GFPT2 interactors, kinases, and substrates enabled the inference of regulatory phospho-signaling dynamics associated with GFPT2. Further, GFPT2 phosphorylation at S244 was identified to be regulated by two potential upstream kinases CHEK1 and PKN1, that showed positive coregulation with kinase activity increasing phosphosites. These findings provide novel insights into the cellular phospho-signaling networks associated with GFPT2, offering potential implications for therapeutic interventions.