Increased Expression of EZH2 Is Mediated by Higher Glycolysis and mTORC1 Activation in Lupus CD4+ T Cells.

Objective: EZH2 is overexpressed in CD4⁺ T cells from patients with systemic lupus erythematosus (SLE). Increased disease activity in SLE patients is associated with a proinflammatory epigenetic shift in naïve CD4⁺ T cells, likely mediated by EZH2. Here we aim to understand the upstream mechanisms underlying EZH2 overexpression in SLE CD4⁺ T cells.

Methods: Naïve CD4⁺ T cells were isolated from SLE patients and then stimulated with anti-CD3/anti-CD28. qPCR and Western blotting were used to measure mRNA and protein expression levels, respectively. 2-Deoxy-d-glucose (2-DG) was used to inhibit glycolysis. mTORC1 signaling was inhibited using rapamycin. Oxidative stress was induced by H₂O₂.

Results: Because glycolysis is increased in SLE CD4⁺ T cells and glycolysis regulates miR-26a and miR-101, which target EZH2, we examined the effect of inhibiting glycolysis on EZH2 expression. 2-DG significantly inhibited EZH2 expression in SLE CD4⁺ T cells. In addition, 2-DG restored the expression of miR-26a and miR-101, suggesting that suppression of EZH2 by 2-DG occurs at the post-transcriptional level. Because mTORC1 is activated in SLE CD4⁺ T cells in part due to increased oxidative stress, and mTORC1 activation increases glycolysis, we hypothesized that mTORC1 mediates increased EZH2 expression. Indeed, inhibiting mTORC1 increased miR-26a and miR-101 and suppressed EZH2 expression in SLE CD4⁺ T cells. Further, H₂O₂ treatment increased EZH2 expression, however, this effect appears to be independent of miR-26a and miR-101.

Conclusion: Increased EZH2 is mediated by activation of mTORC1 and increased glycolysis in SLE CD4⁺ T cells. Therapeutic effects from inhibiting mTOR or glycolysis in SLE might be in part mediated by suppression of EZH2.