MTHFD2 is a metabolic checkpoint controlling effector and regulatory T cell fate and function.

Antigenic stimulation promotes T cell metabolic reprogramming to meet increased biosynthetic, bioenergetic, and signaling demands. We show that the one-carbon (1C) metabolism enzyme methylenetetrahydrofolate dehydrogenase 2 (MTHFD2) regulates de novo purine synthesis and signaling in activated T cells to promote proliferation and inflammatory cytokine production. In pathogenic T helper-17 (Th17) cells, MTHFD2 prevented aberrant upregulation of the transcription factor FoxP3 along with inappropriate gain of suppressive capacity. MTHFD2 deficiency also promoted regulatory T (Treg) cell differentiation. Mechanistically, MTHFD2 inhibition led to depletion of purine pools, accumulation of purine biosynthetic intermediates, and decreased nutrient sensor mTORC1 signaling. MTHFD2 was also critical to regulate DNA and histone methylation in Th17 cells. Importantly, MTHFD2 deficiency reduced disease severity in multiple in vivo inflammatory disease models. MTHFD2 is thus a metabolic checkpoint to integrate purine metabolism with pathogenic effector cell signaling and is a potential therapeutic target within 1C metabolism pathways.
Competing Interests: Declaration of interests J.C.R. is a founder, scientific advisory board member, and stockholder of Sitryx Therapeutics; a scientific advisory board member and stockholder of Caribou Biosciences; a member of the scientific advisory board of Nirogy Therapeutics; has consulted for Merck, Pfizer, and Mitobridge within the past 3 years; and has received research support from Incyte Corp., Calithera Biosciences, and Tempest Therapeutics. J.D.R. is a co-founder and stockholder in Raze Therapeutics, Toran, Serien Therapeutics, and Farber Partners and an advisor and stockholder in Agios Pharmaceuticals, Kadmon Pharmaceuticals, Bantam Pharmaceuticals, Colorado Research Partners, Rafael Holdings, the Barer Institute, and L.E.A.F. Pharmaceuticals; he has received consulting fees and research funding from Pfizer and Rafael and is the inventor of patents held by Princeton University. A.M.C., P.F., and T.B. are employees of Sitryx Therapeutics.
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