Functional Contribution of Multienzyme Glucosome Condensates to Cellular Redox Homeostasis in Cancer Cells

Glucosomes, liquid-liquid phase-separated condensates, are formed in human cells involving phosphofructokinase and enzymes crucial to glycolysis and gluconeogenesis. In cancer cells, these condensates exist as small-, medium-, and large-sized assemblies. Researchers have found that medium-sized glucosomes play a functional role in redirecting glucose flux towards the pentose phosphate pathway (PPP). This pathway is crucial for maintaining cytosolic NADPH levels during oxidative stress.

To test their hypothesis that medium-sized glucosomes regulate cellular redox homeostasis, researchers exposed Hs578T cells to hydrogen peroxide (H2O2) and used high-content imaging to observe the impact. The results showed a significant increase in medium-sized glucosomes in both individual cells and populations exposed to H2O2. Further confirmation came from Seahorse extracellular flux analysis, which revealed that H2O2 effectively diverted glycolytic flux to the PPP through the upregulation of medium-sized glucosomes.

The researchers then explored the glutathione redox cycle as a potential link between medium-sized glucosomes and H2O2 detoxification. They found that treating cells with oxidized glutathione (GSSG), but not reduced glutathione (GSH), led to an increase in cells displaying medium-sized glucosomes. Moreover, using shRNA to knock down glutathione reductase—a protein that converts GSSG back to GSH using NADPH—attenuated H2O2-induced glucosome formation in Hs578T cells.

In conclusion, this study demonstrates that glucosomes play a functional role in metabolic reprogramming, linking glucose metabolism to the glutathione redox cycle to facilitate H2O2 detoxification. This establishes the functional role of glucosomes in cellular redox homeostasis.