Targeting the Mapk13-Tcf1-Slc7a5 Axis via One-Carbon Metabolic Regulation to Prevent Chronic Allograft Vasculopathy.

Chronic allograft vasculopathy (CAV) is driven in part by stem-like CD4(+) T cells, but how these cells sustain their progenitor programs during chronic rejection remains unclear. Here, a metabolic-epigenetic axis is identified in which Mapk13 phosphorylates Tcf1 at T289, enabling Tcf1 to activate the amino acid transporter Slc7a5 and enhance methionine uptake. This rewires one-carbon metabolism and increases H3K4me3 enrichment at the Tcf7 locus, thereby maintaining stem-like CD4(+) T cells within rejecting grafts. Disruption of this circuit-via genetic deletion of Mapk13 or Slc7a5, or through dietary methionine restriction-reduces Tcf1(+) CD4(+) T cell stemness and prevents CAV in mouse models. These findings reveal the Mapk13-Tcf1-Slc7a5 axis as a critical metabolic dependency of pathogenic T cells and highlight one-carbon metabolism as a promising target to promote long-term graft survival.