Glutaredoxin 2 is essential for AML survival through mitochondrial permeability transition pore regulation

Acute myeloid leukemia (AML) patients have a poor five-year survival rate highlighting the need for the identification of new approaches to target this disease. AML is highly dependent on glutathione (GSH) metabolism for survival. While the metabolic role of GSH is well-characterized in AML, the contribution of protein glutathionylation-a reversible modification that protects protein thiols from oxidative damage-remains largely unexplored. Therefore, we sought to elucidate the role of protein glutathionylation in AML pathogenesis. Here, we demonstrate that protein glutathionylation is essential for AML cell survival. Specifically, the loss of glutaredoxin 2 (GLRX2), an enzyme that removes glutathione modifications, resulted in selective primary AML cell death while sparing normal human hematopoietic stem and progenitor cells. Unbiased proteomic analysis revealed increased mitochondrial protein glutathionylation upon GLRX2 depletion, accompanied by mitochondrial dysfunction, including impaired oxidative phosphorylation, reduced mitochondrial membrane potential, and increased opening of the mitochondrial permeability transition pore (mPTP). Further investigation identified ATP5PO, a key regulator of mPTP opening and a component of the ATP synthase complex, as a critical GLRX2 target. Disruption of ATP5PO glutathionylation partially restored mPTP function and rescued AML cell viability following GLRX2 depletion. Moreover, both genetic and pharmacologic inhibition of mPTP opening restored the leukemic potential of primary AML specimens in the absence of GLRX2. By disrupting glutathionylation-dependent mitochondrial homeostasis, this study reveals a novel vulnerability in AML that could inform future therapeutic strategies.