Disruption of nucleotide biosynthesis reprograms mitochondrial metabolism to inhibit adipogenesis
Ontology highlight
ABSTRACT: A key organismal response to overnutrition involves the development of new adipocytes through the process of adipogenesis. Preadipocytes sense changes in the systemic nutrient status and metabolites can directly modulate adipogenesis. We previously identified a role of de novo nucleotide biosynthesis in adipogenesis induction, whereby inhibition of nucleotide biosynthesis suppresses the expression of the transcriptional regulators PPARg and C/EBPa. Here, we set out to identify the global transcriptomic changes associated with the inhibition of nucleotide biosynthesis. Through RNA sequencing (RNAseq), we discovered that mitochondria were the most altered transcriptional signature in response to inhibition of nucleotide biosynthesis. Blocking nucleotide biosynthesis induced rounded mitochondrial morphology, and altered mitochondrial function, and metabolism, reducing levels of tricarboxylic acid cycle intermediates, and increasing fatty acid oxidation (FAO). The loss of mitochondrial function induced by suppression of nucleotide biosynthesis was rescued by exogenous expression of PPARg. Moreover, inhibition of FAO restored PPARg expression, mitochondrial protein expression, and adipogenesis in the presence of nucleotide biosynthesis inhibition, suggesting a regulatory role of nutrient oxidation in differentiation. Collectively, our studies shed light on the link between substrate oxidation and transcription in cell fate determination.
Project description:In cancer patients, metastasis of tumors to sentinel lymph nodes (LN) predicts disease progression and often guides treatment decisions. The mechanisms underlying tumor LN metastasis are poorly understood. Using comparative transcriptomics and metabolomics analyses of primary and LN metastatic tumors in mice, we found that LN metastasis requires that tumor cells undergo a metabolic shift toward fatty acid oxidation (FAO). Transcriptional co-activator yes-associated protein (YAP) is selectively activated in LN metastatic tumors, leading to upregulation of genes in the FAO signaling pathway. Pharmacological inhibition of FAO or genetic ablation of YAP suppressed LN metastasis in mice. Several bioactive bile acids were highly accumulated in the LN metastatic tumor. Inhibition of FAO or YAP may merit exploration as therapeutic strategies for mitigating tumor LN metastasis.
Project description:full title: A mitochondrial long-chain fatty acid oxidation defect in a mouse model leads to dysregulation of plasma long-chain acylcarnitines, dysregulation of plasma amino acids, and an increased reliance on glucocorticoid signaling to maintain euglycemia during fasting. [liver] The liver is a major source of energy substrates during metabolic stress: fasting, prolonged exercise, febrile illness. Fasting-induced hypoglycemia is a characteristic feature of FAO disorders including very long chain acyl-CoA dehydrogenase (VLCAD) deficiency (VLCADD). However, the pathophysiological mechanisms that underlie the diversity of clinical presentation of FAO dysfunction are not known. Here, we investigated the transcriptional response in liver tissue to the FAO defect in a model of VLCADD: the long-chain acyl-CoA dehydrogenase (LCAD) knockout (KO) mouse. We found that differentially expressed genes from the liver were associated with molecular networks annotated for fatty acid oxidation and cholesterol biosynthesis from population-based networks.
Project description:Developmental transitions are guided by master regulatory transcription factors. During adipogenesis, a transcriptional cascade culminates in expression of PPARg and C/EBPa, which orchestrate activation of the adipocyte gene expression program. However, the coactivators controlling PPARg and C/EBPa expression are less well characterized. Here we show the bromodomain-containing protein, BRD4, regulates transcription of PPARg and C/EBPa. Analysis of BRD4 chromatin occupancy reveals that induction of adipogenesis in 3T3L1 fibroblasts provokes dynamic redistribution of BRD4 to de novo super enhancers proximal to genes controlling adipocyte differentiation. BET bromodomain inhibition impedes BRD4 occupancy at these de novo enhancers and disrupts transcription of Pparg and Cebpa, thereby blocking adipogenesis. Furthermore, silencing of these BRD4-occupied distal regulatory elements at the Pparg locus by CRISPRi demonstrates a critical role for these enhancers in the control of Pparg gene expression and adipogenesis in 3T3L1s. Together, these data establish BET bromodomain proteins as time- and context-dependent coactivators of the adipocyte cell state transition.
Project description:We report the HDAC inhibiton of glioblastoma cells causes histone H3K27 acetylation and leads to upreguated OXPHOS master regulator PGC1a which then leads to an increase in mitochondrial fusion, mitochondrial biogenesis and higher mitochondrial oxygen consumption rate coupled with increased fatty acid oxidation (FAO).
Project description:Little is known about metabolic changes accompanying endothelial cell (EC) quiescence. Nonetheless, when dysfunctional, quiescent ECs (QECs) contribute to multiple cardiovascular diseases. ECs need fatty acid β-oxidation (FAO) for proliferation. Surprisingly, we now report that QECs are not hypo-metabolic, but upregulate FAO >3-fold higher than proliferating ECs (PECs), not to support biomass or energy production, but to sustain the TCA cycle for redox homeostasis through NADPH production. Hence, inhibition of FAO-controlling CPT1A promotes EC dysfunction (anti-fibrinolysis, leukocyte infiltration, barrier disruption) by increasing oxidative stress in CPT1AΔEC mice with endothelial CPT1A loss. Mechanistically, Notch1 orchestrates the use of FAO for redox balance in QECs. Supplementation of acetate (metabolized to acetyl-CoA) induces vasculoprotection against oxidative stress and EC dysfunction in CPT1AΔEC mice, possibly creating therapeutic opportunities. Thus, ECs use FAO for vasculoprotection against their high oxygen (oxidative stress-prone) milieu, and for different metabolic purposes dependent on their proliferation versus quiescence status.
Project description:The role of peroxisome proliferator-activated receptor M-NM-4 (PPARM-NM-4) activation on global gene expression and mitochondrial fuel utilization were investigated in human myotubes. Only 21 genes were up-regulated and 3 genes were down-regulated after activation by the PPARM-NM-4 agonist GW501516. Pathway analysis showed up-regulated mitochondrial fatty acid oxidation, TCA cycle and cholesterol biosynthesis. GW501516 increased oleic acid oxidation and mitochondrial oxidative capacity by 2-fold. Glucose uptake and oxidation were reduced, but total substrate oxidation was not affected, indicating a fuel switch from glucose to fatty acid. Cholesterol biosynthesis was increased, but lipid biosynthesis and mitochondrial content were not affected. This study confirmed that the principal effect of PPARM-NM-4 activation was to increase mitochondrial fatty acid oxidative capacity. Our results further suggest that PPARM-NM-4 activation reduced glucose utilization through a switch in mitochondrial substrate preference by up-regulating pyruvate dehydrogenase kinase isozyme 4 and genes involved in lipid metabolism and fatty acid oxidation. Keywords: Expression profiling by array Human myotubes from four donors were exposed to a PPARM-NM-4 agonist or control for 96 h after which gene expression was profiled.
Project description:The solid tumor microenvironment (TME) imprints a compromised metabolic state in tumor infiltrating T cells (TILs) hallmarked by the inability to maintain effective energy synthesis for antitumor function and survival. T cells in the TME must catabolize lipids via mitochondrial fatty acid oxidation (FAO) to supply energy in nutrient stress, and it is established that T cells enriched in FAO are adept at cancer control.However, endogenous TILs and unmodified cellular therapy products fail to sustain bioenergetics in tumors. Using patient samples and mouse models, we reveal that the solid TME imposes perpetual acetyl-CoA carboxylase (ACC) activity, invoking lipid biogenesis and storage in TILs that directly opposes FAO. Using metabolic, lipidomic, and confocal imaging strategies, we find that restricting ACC rewires T cell metabolism, enabling energy maintenance in TME stress. Moreover, limiting ACC activity potentiates a gene and phenotypic program indicative of T cell longevity, engendering T cells with increased survival and polyfunctionality, with the ability to control solid cancer.
Project description:Short chain enoyl-CoA hydratase 1 (ECHS1) is involved in the second step of mitochondrial fatty acid β-oxidation (FAO), catalysing the hydration of short chain enoyl-CoA esters to short chain 3-hyroxyl-CoA esters. Genetic deficiency in ECHS1 (ECHS1D) is associated with a specific subset of Leigh Syndrome, a disease typically caused by defects in oxidative phosphorylation (OXPHOS). Here, we examined the molecular pathogenesis of ECHS1D using a CRISPR/Cas9 edited human cell ‘knockout’ model and fibroblasts from ECHS1D patients. Transcriptome analysis of ECHS1 ‘knockout’ cells showed reductions in key mitochondrial pathways, including the TCA cycle, receptor mediated mitophagy and nucleotide biosynthesis. Subsequent proteomic analyses confirmed these reductions and revealed additional defects in mitochondrial oxidoreductase activity and fatty acid β-oxidation. Functional analysis of ECHS1 ‘knockout’ cells showed reduced mitochondrial oxygen consumption rates when metabolising glucose or OXPHOS complex I-linked substrates, as well as decreased complex I and complex IV enzyme activities. ECHS1 ‘knockout’ cells also exhibited decreased OXPHOS protein complex steady-state levels (complex I, complex III2, complex IV, complex V and supercomplexes CIII2/CIV and CI/CIII2/CIV). Patient fibroblasts exhibit varied reduction of mature OXPHOS complex steady-state levels, with defects detected in CIII2, CIV, CV and the CI/CIII2/CIV supercomplex. Overall, these findings highlight the contribution of defective OXPHOS function, in particular complex I deficiency, to the molecular pathogenesis of ECHS1D.
Project description:By utilizing proteomic and transcriptomic analysis coupled with untargeted polar and non-polar metabolite analysis by liquid chromatography/mass spectrometry, we identified a specific metabolic program elicited by c-MET inhibition. Interference with c-MET drives oxidative metabolism by increasing fatty acid oxidation (FAO) and glucose anaplerosis, which was orchestrated by the master-regulator, PGC1α. Based on a drug screen, we further found that the mitochondrial matrix chaperone inhibitor, gamitrinib, along with c-MET inhibition causes synergistic cell death, which was mechanistically related to the ability of gamitrinib to suppress oxidative metabolism. In alignment with these findings, FAO inhibitor, etomoxir, enhanced the anti-proliferative effects of c-MET inhibition as well. Both combination therapies were active in vivo, suggesting two novel potential combination therapies, involving c-MET inhibitors.