Glycogenolysis-derived G1P initiates PPP via glycogen-G6PD phase separation and compartmentalization (PRJCA039233)

Glucose-6-phosphate (G6P) is a key metabolic molecule that regulates reactive oxygen species (ROS) homeostasis by flowing along the pentose phosphate pathway (PPP) to generate NADPH, which then donates hydrogen atoms to H2O2, thus converting H2O2 to water. Although glucose phosphorylation has long been thought to provide G6P for pentose phosphate pathway (PPP), the role of glycogenolysis-derived G6P is neglected. Here, we show that G6P derived from glycogenolysis, rather than glucose phosphorylation, flows to PPP for ROS clearance using CD8+ memory T (Tm) cells and inflammatory macrophages as model cells both in vitro and in vivo. This is attributable to G1P, the first metabolite of glycogenolysis, which can allosterically act on and allow G6P dehydrogenase (G6PD) to bind to glycogen liquid-liquid phase separation (LLPS). This glycogen-G6PD LLPS further recruits PPP enzymes to undergo compartmentalization to trigger the cascade reaction of PPP enzymes and metabolites. Based on mechanistic elucidation, we additionally showed that G1P can act as an antitumor immunotherapeutic agent by modulating memory fitness and maintenance of tumor-reactive CD8+ T cells. These findings revealed a previously unknown function of glycogen metabolism, which is of paramount importance in the regulation of PPP and redox homeostasis.