Abstract 361: Deacetylation of Lc3 Drives Autophagy and Proteome Remodeling in Skeletal Muscle During Oncometabolic Stress

Abstract

Metabolic rewiring is a hallmark of cancer and muscle cells. In isocitrate dehydrogenase 1 and 2 mutant tumors, increased plasma levels of the oncometabolite D-2-hydroxyglutarate (D2-HG) are associated with systemic effects, including myopathy. Our recent in vivo work showed that increased D2-HG supply by IDH-mutant cells causes heart and skeletal muscle atrophy, and decreases cellular ATP and NADH. Although heart failure and cachexia in cancer are commonly associated with chemotherapy, cancer survivors have a 5-fold increased risk of heart failure independent of any cytostatic treatment. The connection between metabolic and proteomic remodeling in this context remain poorly understood. We hypothesize that D2-HG-mediated alpha-ketoglutarate dehydrogenase (AKGDH) inhibition in myocytes results in metabolomic perturbations, increases autophagy and proteomic remodeling. Here, we report that LC3, a key regulator of autophagy, is activated in the nucleus of myocytes in presence of D2-HG through deacetylation by the nuclear deacetylase Sirt1. Activation of Sirt1 is driven by increased NAD + levels through D2-HG-mediated AKGDH inhibition. We used LC3 mutants with arginine and glutamine replacements at lysine residues to show that deacetylation of LC3 at K49 and K51 by Sirt1 shifts LC3 distribution from the nucleus into the cytosol, where it is able to undergo lipidation at pre-autophagic membranes. Live cell imaging with GFP-tagged LC3 in L6 myocytes indicated that the cycle of acetylation-deacetylation allows LC3 to redistribute from the nucleus to the cytosol within less than 24 h. Co-immunoprecipitation of LC3 followed by proteomics analysis revealed that LC3 binds to dynein in presence of D2-HG. Furthermore, D2-HG promoted skeletal muscle atrophy and reduced grip strength in wild-type C57BL/J6 mice in vivo. Using LC-MS/MS-based proteomics and metabolomics combined with RNA-sequencing, we assessed the effect of D2-HG on a systems level in skeletal muscle. Pathway-enrichment analysis revealed that D2-HG induces upregulation of key metabolic enzymes involved in glycolysis and the pentose phosphate pathway. In short, autophagy activation supports proteome remodeling in muscle cells during IDH-mutant leukemia.