1. GLUD1 determines murine muscle stem cell fate by controlling mitochondrial glutamate levels.
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Soro-Arnáiz, Inés, Fitzgerald, Gillian, Cherkaoui, Sarah, Zhang, Jing, Gilardoni, Paola, Ghosh, Adhideb, Bar-Nur, Ori, Masschelein, Evi, Maechler, Pierre, Zamboni, Nicola, Poms, Martin, Cremonesi, Alessio, Garcia-Cañaveras, Juan Carlos, De Bock, Katrien, and Morscher, Raphael Johannes
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KREBS cycle , *STEM cells , *MUSCLE regeneration , *MUSCLE cells , *METABOLIC regulation - Abstract
Muscle stem cells (MuSCs) enable muscle growth and regeneration after exercise or injury, but how metabolism controls their regenerative potential is poorly understood. We describe that primary metabolic changes can determine murine MuSC fate decisions. We found that glutamine anaplerosis into the tricarboxylic acid (TCA) cycle decreases during MuSC differentiation and coincides with decreased expression of the mitochondrial glutamate deaminase GLUD1. Deletion of Glud1 in proliferating MuSCs resulted in precocious differentiation and fusion, combined with loss of self-renewal in vitro and in vivo. Mechanistically, deleting Glud1 caused mitochondrial glutamate accumulation and inhibited the malate-aspartate shuttle (MAS). The resulting defect in transporting NADH-reducing equivalents into the mitochondria induced compartment-specific NAD+/NADH ratio shifts. MAS activity restoration or directly altering NAD+/NADH ratios normalized myogenesis. In conclusion, GLUD1 prevents deleterious mitochondrial glutamate accumulation and inactivation of the MAS in proliferating MuSCs. It thereby acts as a compartment-specific metabolic brake on MuSC differentiation. [Display omitted] • Glutamine is the main TCA cycle substrate in MuSCs, decreasing with differentiation • Glud1 loss impairs MuSC self-renewal and causes imbalanced differentiation and fusion • Glud1 loss traps mitochondrial glutamate and disrupts the malate-aspartate shuttle (MAS) • Restoring MAS in Glud1- deficient MuSCs blocks early differentiation and fusion imbalance Soro-Arnáiz and Fitzgerald et al. leverage ex vivo and in vivo models to identify how Glud1 determines muscle stem cell (MuSC) fate by controlling mitochondrial glutamate levels and, in turn, the activity of the malate aspartate shuttle. The resulting compartment-specific shift in NAD+/NADH ratios promotes precocious MuSC differentiation and fusion. [ABSTRACT FROM AUTHOR]
- Published
- 2024
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