Deletion of the mitochondria-shaping protein Opa1 during early thymocyte maturation impacts mature memory T cell metabolism

OPA1, a mitochondria-shaping protein controlling cristae biogenesis and respiration, is required for memory T cell function, but whether it affects intrathymic T cell development is unknown. Here we show that OPA1 is necessary for thymocyte maturation at the double negative (DN)3 stage when rearrangement of the T-cell receptor ß (Tcrß) locus occurs. By profiling mitochondrial function at different stages of thymocyte maturation, we find that DN3 cells rely on oxidative phosphorylation (OXPHOS). Consistently, Opa1 deletion during early T cell development impairs respiration of DN3 cells and reduces their number. Opa1-deficient DN3 cells indeed display stronger TCR signaling and are more prone to cell death. The surviving Opa1-/- thymocytes that reach the periphery as mature T cells display an Effector Memory phenotype even in the absence of antigenic stimulation but are unable to generate metabolically fit long-term memory T cells. Thus, mitochondrial defects early during T cell development affect mature T cell function. Overall design: RNA-seq was performed on DN3 and DN4 thymocytes freshly sorted form 6 weeks old Wt;Lck-Cre+ and Opa1fl/fl;Lck-Cre+ mice