在甲基丙二酸血症和丙酸血症的细胞模型的多组学研究中揭示了丝氨酸代谢的失调。
Multi-omics studies in cellular models of methylmalonic acidemia and propionic acidemia reveal dysregulation of serine metabolism.
机构信息
Department of Genetic Medicine, Johns Hopkins University School of Medicine, Baltimore, MD, United States of America.
Institute of Bioinformatics, Bengalaru, India; Manipal Academy of Higher Education (MAHE), Manipal 576104, India.
出版信息
Biochim Biophys Acta Mol Basis Dis. 2019 Dec 1;1865(12):165538. doi: 10.1016/j.bbadis.2019.165538. Epub 2019 Aug 23.
BACKGROUND
Methylmalonic acidemia (MMA) and propionic acidemia (PA) are related disorders of mitochondrial propionate metabolism, caused by defects in methylmalonyl-CoA mutase (MUT) and propionyl-CoA carboxylase (PCC), respectively. These biochemical defects lead to a complex cascade of downstream metabolic abnormalities, and identification of these abnormal pathways has important implications for understanding disease pathophysiology. Using a multi-omics approach in cellular models of MMA and PA, we identified serine and thiol metabolism as important areas of metabolic dysregulation.
METHODS
We performed global proteomic analysis of fibroblasts and untargeted metabolomics analysis of plasma from individuals with MMA to identify novel pathways of dysfunction. We probed these novel pathways in CRISPR-edited, MUT and PCCA null HEK293 cell lines via targeted metabolomics, gene expression analysis, and flux metabolomics tracing utilization of C-glucose.
RESULTS
Proteomic analysis of fibroblasts identified upregulation of multiple proteins involved in serine synthesis and thiol metabolism including: phosphoserine amino transferase (PSAT1), cystathionine beta synthase (CBS), and mercaptopyruvate sulfurtransferase (MPST). Metabolomics analysis of plasma revealed significantly increased levels of cystathionine and glutathione, central metabolites in thiol metabolism. CRISPR-edited MUT and PCCA HEK293 cells recapitulate primary defects of MMA and PA and have upregulation of transcripts associated with serine and thiol metabolism including PSAT1. C-glucose flux metabolomics in MUT and PCCA null HEK293 cells identified increases in serine de novo biosynthesis, serine transport, and abnormal downstream TCA cycle utilization.
CONCLUSION
We identified abnormal serine metabolism as a novel area of cellular dysfunction in MMA and PA, thus introducing a potential new target for therapeutic investigation.
背景
甲基丙二酸血症（MMA）和丙酸血症（PA）是与线粒体丙酸代谢相关的疾病，分别由甲基丙二酰辅酶 A 变位酶（MUT）和丙酰辅酶 A 羧化酶（PCC）缺陷引起。这些生化缺陷导致下游代谢异常的复杂级联反应，识别这些异常途径对理解疾病发病机制具有重要意义。我们在 MMA 和 PA 的细胞模型中采用多组学方法，发现丝氨酸和硫醇代谢是代谢失调的重要领域。
方法
我们对成纤维细胞进行了全局蛋白质组分析，并对 MMA 个体的血浆进行了非靶向代谢组学分析，以确定功能障碍的新途径。我们通过靶向代谢组学、基因表达分析和 C-葡萄糖通量代谢追踪利用，在 CRISPR 编辑的、MUT 和 PCCA 缺失的 HEK293 细胞系中探究这些新途径。
结果
成纤维细胞的蛋白质组分析鉴定出多个涉及丝氨酸合成和硫醇代谢的蛋白质上调，包括磷酸丝氨酸氨基转移酶（PSAT1）、胱硫醚-β 合酶（CBS）和巯基丙酮酸硫转移酶（MPST）。血浆代谢组学分析显示半胱氨酸和谷胱甘肽水平显著升高，这是硫醇代谢的中心代谢物。CRISPR 编辑的 MUT 和 PCCA HEK293 细胞重现了 MMA 和 PA 的主要缺陷，并上调了与丝氨酸和硫醇代谢相关的转录本，包括 PSAT1。MUT 和 PCCA 缺失的 HEK293 细胞的 C-葡萄糖通量代谢组学鉴定出丝氨酸从头合成、丝氨酸转运和异常下游 TCA 循环利用增加。
结论
我们确定异常的丝氨酸代谢是 MMA 和 PA 细胞功能障碍的一个新领域，从而为治疗研究引入了一个潜在的新靶点。
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