目的:恶病质是一种代谢紊乱,与癌症和心力衰竭并存。这种综合症影响了全世界超过三千万人,占所有癌症死亡人数的20%。在急性髓细胞性白血病中,代谢酶异柠檬酸脱氢酶1和2的体细胞突变会导致代谢产物D2-羟基戊二酸(D2-HG)的产生。D2-HG的产生增加与心脏和骨骼肌萎缩有关,但是代谢和蛋白质组重塑之间的机制联系仍然知之甚少。因此,我们评估了D2-HG引起的细胞代谢应激如何激活自噬并导致骨骼肌损失.
方法:我们量化了基因组,代谢组学,和蛋白质组的变化在培养的骨骼肌细胞和小鼠模型的IDH突变白血病使用RNA测序,质谱,和计算建模。
结果:D2-HG损害肌管中的NADH氧化还原稳态。增加的NAD+水平驱动核脱乙酰酶Sirt1的激活,这导致自噬的关键调节因子LC3的脱乙酰和激活。使用LC3突变体,我们证实通过Sirt1对LC3的去乙酰化将其分布从细胞核转移到细胞质中,在那里它可以在自噬前膜经历脂化。Sirt1沉默或p300过表达减弱了肌管中的自噬激活。在体内,我们发现男性与男性对D2-HG的反应增加了肌肉萎缩和握力降低雌性老鼠在雄性小鼠中,糖酵解中间体积累,氧化磷酸化机制的蛋白质表达减少。相比之下,雌性动物上调相同的蛋白质,减弱体内表型。网络建模和机器学习算法使我们能够识别出调节小鼠骨骼肌代谢适应所必需的候选蛋白质。
结论:我们的多组学方法揭示了骨骼肌中响应D2-HG的新的代谢脆弱性,并为识别恶病质的治疗靶点提供了一个概念框架。
OBJECTIVE: Cachexia is a metabolic disorder and comorbidity with cancer and heart failure. The syndrome impacts more than thirty million people worldwide, accounting for 20% of all cancer deaths. In acute myeloid leukemia, somatic mutations of the metabolic enzyme isocitrate dehydrogenase 1 and 2 cause the production of the oncometabolite D2-hydroxyglutarate (D2-HG). Increased production of D2-HG is associated with heart and skeletal muscle atrophy, but the mechanistic links between metabolic and proteomic remodeling remain poorly understood. Therefore, we assessed how oncometabolic stress by D2-HG activates autophagy and drives skeletal muscle loss.
METHODS: We quantified genomic, metabolomic, and proteomic changes in cultured skeletal muscle cells and mouse models of IDH-mutant leukemia using RNA sequencing, mass spectrometry, and computational modeling.
RESULTS: D2-HG impairs NADH redox homeostasis in myotubes. Increased NAD+ levels drive activation of nuclear deacetylase Sirt1, which causes deacetylation and activation of LC3, a key regulator of autophagy. Using LC3 mutants, we confirm that deacetylation of LC3 by Sirt1 shifts its distribution from the nucleus into the cytosol, where it can undergo lipidation at pre-autophagic membranes. Sirt1 silencing or p300 overexpression attenuated autophagy activation in myotubes. In vivo, we identified increased muscle atrophy and reduced grip strength in response to D2-HG in male vs. female mice. In male mice, glycolytic intermediates accumulated, and protein expression of oxidative phosphorylation machinery was reduced. In contrast, female animals upregulated the same proteins, attenuating the phenotype in vivo. Network modeling and machine learning algorithms allowed us to identify candidate proteins essential for regulating oncometabolic adaptation in mouse skeletal muscle.
CONCLUSIONS: Our multi-omics approach exposes new metabolic vulnerabilities in response to D2-HG in skeletal muscle and provides a conceptual framework for identifying therapeutic targets in cachexia.