Phosphoglycerate mutase regulates Treg differentiation through control of serine synthesis and one-carbon metabolism

Godfrey et al., eLife, 2025 asked which glycolytic enzyme decides whether a CD4 T cell becomes a regulatory T cell. Published human transcriptomic and proteomic datasets pointed at phosphoglycerate mutase, which was the most differentially expressed glycolytic gene in induced regulatory T cells and was raised again in the most suppressive subset of tumour infiltrating regulatory T cells. The team then had to test the enzyme directly in primary mouse T cells.

They did it with AUMsilence sdASO. Two custom sets were used, one against Pgam and one against Phgdh, alongside a scrambled control set and a fluorescein labelled scrambled control. The oligonucleotides were dissolved in phosphate buffered saline and added to the culture medium at 10 μM from day zero. No transfection reagent appears anywhere in the study, and the labelled control showed near complete uptake by cultured CD4 cells within 24 hours. Silencing Pgam cut PGAM1 protein by about 40% by mean fluorescence intensity, a figure the authors give in their published response to review rather than in the article itself.

Silencing Pgam reduced regulatory T cell differentiation by CD25 and FOXP3, without costing viability, and pushed the transcriptome toward a T helper 17 profile with Il17, Il22 and Il9 up and Foxp3 down. Those cells were then measurably worse at suppressing effector T cell proliferation, and methylation at the Foxp3 Treg specific demethylated region went up. The second oligonucleotide made the argument mechanistic: silencing Phgdh, the rate limiting enzyme of serine synthesis, moved differentiation in the opposite direction and increased regulatory T cell generation. Read together, the two silencing arms show that phosphoglycerate mutase supports regulatory T cells by holding down flux into de novo serine synthesis, which feeds one carbon metabolism and the methylation of regulatory T cell genes. The animal work in the paper, a serine and glycine free diet in experimental autoimmune encephalomyelitis and an adoptive transfer colitis model, tested the same axis with diet and a small molecule rather than with oligonucleotides.