Electron transport chain inhibition increases cellular dependence on purine transport and salvage.

Cancer cells reprogram their metabolism to support cell growth and proliferation in harsh environments. While many studies have documented the importance of mitochondrial oxidative phosphorylation (OXPHOS) in tumor growth, some cancer cells experience conditions of reduced OXPHOS in vivo and induce alternative metabolic pathways to compensate. To assess how human cells respond to mitochondrial dysfunction, we performed metabolomics in fibroblasts and plasma from patients with inborn errors of mitochondrial metabolism, and in cancer cells subjected to inhibition of the electron transport chain (ETC).

In vivo isotope tracing reveals a requirement for the electron transport chain in glucose and glutamine metabolism by tumors.

In mice and humans with cancer, intravenous C-glucose infusion results in C labeling of tumor tricarboxylic acid (TCA) cycle intermediates, indicating that pyruvate oxidation in the TCA cycle occurs in tumors. The TCA cycle is usually coupled to the electron transport chain (ETC) because NADH generated by the cycle is reoxidized to NAD by the ETC. However, C labeling does not directly report ETC activity, and other pathways can oxidize NADH, so the ETC's role in these labeling patterns is unverified.

De novo pyrimidine synthesis is a targetable vulnerability in IDH mutant glioma.

Mutations affecting isocitrate dehydrogenase (IDH) enzymes are prevalent in glioma, leukemia, and other cancers. Although mutant IDH inhibitors are effective against leukemia, they seem to be less active in aggressive glioma, underscoring the need for alternative treatment strategies. Through a chemical synthetic lethality screen, we discovered that IDH1-mutant glioma cells are hypersensitive to drugs targeting enzymes in the de novo pyrimidine nucleotide synthesis pathway, including dihydroorotate dehydrogenase (DHODH).

Compartmentalized metabolism supports midgestation mammalian development.

Mammalian embryogenesis requires rapid growth and proper metabolic regulation. Midgestation features increasing oxygen and nutrient availability concomitant with fetal organ development. Understanding how metabolism supports development requires approaches to observe metabolism directly in model organisms in utero.

A Short Isoform of Spermatogenic Enzyme GAPDHS Functions as a Metabolic Switch and Limits Metastasis in Melanoma.

Unlabelled: Despite being the leading cause of cancer deaths, metastasis remains a poorly understood process. To identify novel regulators of metastasis in melanoma, we performed a large-scale RNA sequencing screen of 48 samples from patient-derived xenograft (PDX) subcutaneous melanomas and their associated metastases. In comparison with primary tumors, expression of glycolytic genes was frequently decreased in metastases, whereas expression of some tricarboxylic acid (TCA) cycle genes was increased in metastases.

BMAL1 drives muscle repair through control of hypoxic NAD regeneration in satellite cells.

The process of tissue regeneration occurs in a developmentally timed manner, yet the role of circadian timing is not understood. Here, we identify a role for the adult muscle stem cell (MuSC)-autonomous clock in the control of muscle regeneration following acute ischemic injury. We observed greater muscle repair capacity following injury during the active/wake period as compared with the inactive/rest period in mice, and loss of within MuSCs leads to impaired muscle regeneration.

Loss of glucose 6-phosphate dehydrogenase function increases oxidative stress and glutaminolysis in metastasizing melanoma cells.

The pentose phosphate pathway is a major source of NADPH for oxidative stress resistance in cancer cells but there is limited insight into its role in metastasis, when some cancer cells experience high levels of oxidative stress. To address this, we mutated the substrate binding site of glucose 6-phosphate dehydrogenase (G6PD), which catalyzes the first step of the pentose phosphate pathway, in patient-derived melanomas. mutant melanomas had significantly decreased G6PD enzymatic activity and depletion of intermediates in the oxidative pentose phosphate pathway.

The cardiac-enriched microprotein mitolamban regulates mitochondrial respiratory complex assembly and function in mice.

Emerging evidence indicates that a subset of RNA molecules annotated as noncoding contain short open reading frames that code for small functional proteins called microproteins, which have largely been overlooked due to their small size. To search for cardiac-expressed microproteins, we used a comparative genomics approach and identified mitolamban (Mtlbn) as a highly conserved 47-amino acid transmembrane protein that is abundantly expressed in the heart. Mtlbn localizes specifically to the inner mitochondrial membrane where it interacts with subunits of complex III of the electron transport chain and with mitochondrial respiratory supercomplexes.

Aspartate availability limits hematopoietic stem cell function during hematopoietic regeneration.

The electron transport chain promotes aspartate synthesis, which is required for cancer cell proliferation. However, it is unclear whether aspartate is limiting in normal stem cells. We found that mouse hematopoietic stem cells (HSCs) depend entirely on cell-autonomous aspartate synthesis, which increases upon HSC activation.

The requirement for pyruvate dehydrogenase in leukemogenesis depends on cell lineage.

Cancer cells are metabolically similar to their corresponding normal tissues. Differences between cancers and normal tissues may reflect reprogramming during transformation or maintenance of the metabolism of the specific normal cell type that originated the cancer. Here, we compare glucose metabolism in hematopoiesis and leukemia.

Metabolomic profiling of rare cell populations isolated by flow cytometry from tissues.

Little is known about the metabolic regulation of rare cell populations because most metabolites are hard to detect in small numbers of cells. We previously described a method for metabolomic profiling of flow cytometrically isolated hematopoietic stem cells (HSCs) that detects 60 metabolites in 10,000 cells (Agathocleous et al., 2017).