Browsing by Subject "Energy metabolism"

Now showing 1 - 10 of 11
  • Thumbnail Image
    Item
    Allele-Specific Reprogramming of Cancer Metabolism by the Long Non-coding RNA CCAT2
    (Elsevier, 2016-02-18) Redis, Roxana S.; Vela, Luz E.; Lu, Weiqin; de Oliveira, Juliana Ferreira; Ivan, Cristina; Rodriguez-Aguayo, Cristian; Adamoski, Douglas; Pasculli, Barbara; Taguchi, Ayumu; Chen, Yunyun; Fernandez, Agustin F.; Valledor, Luis; Van Roosbroeck, Katrien; Chang, Samuel; Shah, Maitri; Kinnebrew, Garrett; Han, Leng; Atlasi, Yaser; Cheung, Lawrence H.; Huang, Gilbert Yuanjay; Monroig, Paloma; Ramirez, Marc S.; Ivkovic, Tina Catela; Van, Long; Ling, Hui; Gafà, Roberta; Kapitanovic, Sanja; Lanza, Giovanni; Bankson, James A.; Huang, Peng; Lai, Stephan Y.; Bast, Robert C.; Rosenblum, Michael G.; Radovich, Milan; Ivan, Mircea; Bartholomeusz, Geoffrey; Liang, Han; Fraga, Mario F.; Widger, William R.; Hanash, Samir; Berindan-Neagoe, Ioana; Lopez-Berestein, Gabriel; Ambrosio, Andre L.B.; Dias, Sandra M Gomes; Calin, George A.; Department of Surgery, IU School of Medicine
    Altered energy metabolism is a cancer hallmark as malignant cells tailor their metabolic pathways to meet their energy requirements. Glucose and glutamine are the major nutrients that fuel cellular metabolism, and the pathways utilizing these nutrients are often altered in cancer. Here, we show that the long ncRNA CCAT2, located at the 8q24 amplicon on cancer risk-associated rs6983267 SNP, regulates cancer metabolism in vitro and in vivo in an allele-specific manner by binding the Cleavage Factor I (CFIm) complex with distinct affinities for the two subunits (CFIm25 and CFIm68). The CCAT2 interaction with the CFIm complex fine-tunes the alternative splicing of Glutaminase (GLS) by selecting the poly(A) site in intron 14 of the precursor mRNA. These findings uncover a complex, allele-specific regulatory mechanism of cancer metabolism orchestrated by the two alleles of a long ncRNA.
  • Thumbnail Image
    Item
    Bioenergetic characterization of a shallow-sea hydrothermal vent system: Milos Island, Greece
    (Public Library of Science, 2020-06-05) Lu, Guang-Sin; LaRowe, Douglas E.; Fike, David A.; Druschel, Gregory K.; Gilhooly, William P., III; Price, Roy E.; Amend, Jan P.; Earth and Environmental Sciences, School of Science
    Shallow-sea hydrothermal systems, like their deep-sea and terrestrial counterparts, can serve as relatively accessible portals into the microbial ecology of subsurface environments. In this study, we determined the chemical composition of 47 sediment porewater samples along a transect from a diffuse shallow-sea hydrothermal vent to a non-thermal background area in Paleochori Bay, Milos Island, Greece. These geochemical data were combined with thermodynamic calculations to quantify potential sources of energy that may support in situ chemolithotrophy. The Gibbs energies (ΔGr) of 730 redox reactions involving 23 inorganic H-, O-, C-, N-, S-, Fe-, Mn-, and As-bearing compounds were calculated. Of these reactions, 379 were exergonic at one or more sampling locations. The greatest energy yields were from anaerobic CO oxidation with NO2- (-136 to -162 kJ/mol e-), followed by reactions in which the electron acceptor/donor pairs were O2/CO, NO3-/CO, and NO2-/H2S. When expressed as energy densities (where the concentration of the limiting reactant is taken into account), a different set of redox reactions are the most exergonic: in sediments affected by hydrothermal input, sulfide oxidation with a range of electron acceptors or nitrite reduction with different electron donors provide 85~245 J per kg of sediment, whereas in sediments less affected or unaffected by hydrothermal input, various S0 oxidation reactions and aerobic respiration reactions with several different electron donors are most energy-yielding (80~95 J per kg of sediment). A model that considers seawater mixing with hydrothermal fluids revealed that there is up to ~50 times more energy available for microorganisms that can use S0 or H2S as electron donors and NO2- or O2 as electron acceptors compared to other reactions. In addition to revealing likely metabolic pathways in the near-surface and subsurface mixing zones, thermodynamic calculations like these can help guide novel microbial cultivation efforts to isolate new species.
  • Thumbnail Image
    Item
    Cilia and Obesity
    (Cold Spring Harbor Laboratory Press, 2017-07-05) Vaisse, Christian; Reiter, Jeremy F.; Berbari, Nicolas F.; Biology, School of Science
    The ciliopathies Bardet-Biedl syndrome and Alström syndrome cause obesity. How ciliary dysfunction leads to obesity has remained mysterious, partly because of a lack of understanding of the physiological roles of primary cilia in the organs and pathways involved in the regulation of metabolism and energy homeostasis. Historically, the study of rare monogenetic disorders that present with obesity has informed our molecular understanding of the mechanisms involved in nonsyndromic forms of obesity. Here, we present a framework, based on genetic studies in mice and humans, of the molecular and cellular pathways underlying long-term regulation of energy homeostasis. We focus on recent progress linking these pathways to the function of the primary cilia with a particular emphasis on the roles of neuronal primary cilia in the regulation of satiety.
  • Thumbnail Image
    Item
    Deletion of mitochondrial calcium uniporter incompletely inhibits calcium uptake and induction of the permeability transition pore in brain mitochondria
    (American Society for Biochemistry and Molecular Biology, 2018-10-05) Hamilton, James; Brustovetsky, Tatiana; Rysted, Jacob E.; Lin, Zhihong; Usachev, Yuriy M.; Brustovetsky, Nickolay; Pharmacology and Toxicology, School of Medicine
    Ca2+ influx into mitochondria is mediated by the mitochondrial calcium uniporter (MCU), whose identity was recently revealed as a 40-kDa protein that along with other proteins forms the mitochondrial Ca2+ uptake machinery. The MCU is a Ca2+-conducting channel spanning the inner mitochondrial membrane. Here, deletion of the MCU completely inhibited Ca2+ uptake in liver, heart, and skeletal muscle mitochondria. However, in brain nonsynaptic and synaptic mitochondria from neuronal somata/glial cells and nerve terminals, respectively, the MCU deletion slowed, but did not completely block, Ca2+ uptake. Under resting conditions, brain MCU-KO mitochondria remained polarized, and in brain MCU-KO mitochondria, the electrophoretic Ca2+ ionophore ETH129 significantly accelerated Ca2+ uptake. The residual Ca2+ uptake in brain MCU-KO mitochondria was insensitive to inhibitors of mitochondrial Na+/Ca2+ exchanger and ryanodine receptor (CGP37157 and dantrolene, respectively), but was blocked by the MCU inhibitor Ru360. Respiration of WT and MCU-KO brain mitochondria was similar except that for mitochondria that oxidized pyruvate and malate, Ca2+ more strongly inhibited respiration in WT than in MCU-KO mitochondria. Of note, the MCU deletion significantly attenuated but did not completely prevent induction of the permeability transition pore (PTP) in brain mitochondria. Expression level of cyclophilin D and ATP content in mitochondria, two factors that modulate PTP induction, were unaffected by MCU-KO, whereas ADP was lower in MCU-KO than in WT brain mitochondria. Our results suggest the presence of an MCU-independent Ca2+ uptake pathway in brain mitochondria that mediates residual Ca2+ influx and induction of PTP in a fraction of the mitochondrial population.
  • Thumbnail Image
    Item
    Food attentional biases and adiposity: are energy intake and external eating mediators of this relationship?
    (2015-08) Vrany, Elizabeth; Stewart, Jesse C.; Cyders, Melissa Anne; Mosher, Catherine Esther
    Obesity is a substantial threat to the health of over a third of adults in the United States. Some evidence suggests that food attentional bias, or the tendency to automatically direct attention toward food-related stimuli in the environment, may contribute to the development of obesity in susceptible individuals. This study hypothesized that (1) food attentional bias would be positively associated with adiposity, (2) food attentional bias would be positively associated with energy intake and external eating, and (3) energy intake and external eating would partially mediate the association between food attentional bias and adiposity. Data were collected from a sample of 120 undergraduate students. Three measures of food attentional bias were obtained: reaction time bias obtained from a visual dot-probe task and direction bias and duration bias obtained from eye tracking. Adiposity indices of body mass index (kg/m2) and body fat percent were measured using standard medical devices. Data were obtained for two mediators: 1) energy intake was assessed by web-based automated 24-hour dietary recall and 2) external eating was assessed using the External Eating Subscale of the Dutch Eating Behavior Questionnaire. Separate linear regression models examining the association between each measure of food attentional bias with each measure of adiposity (adjusted for age, sex, race/ethnicity, and subjective hunger) indicated no associations. Similarly, linear regression analyses revealed no associations between measures of food attentional bias and energy intake or external eating. Models testing for statistical mediation demonstrated that energy intake and external eating were not significant mediators. However, mediation analyses demonstrated a significant overall effect and direct effect between direction bias and BMI in a reduced sample used to test for energy intake as a mediator, suggesting the presence of an association which may not have been detected in the larger sample due to methodological issues, measurement error, or type I error. Despite the overall null results, these findings, in conjunction with previous studies on food attentional biases and adiposity, highlight the need for future investigations examining prospective associations between food attentional bias and adiposity.
  • Thumbnail Image
    Item
    MondoA deficiency enhances sprint performance in mice
    (Portland Press, 2014-11-15) Imamura, Minako; Hung-Junn Chang, Benny; Kohjima, Motoyuki; Li, Ming; Hwang, Byounghoon; Taegtmeyer, Heinrich; Harris, Robert A.; Chan, Lawrence; Department of Biochemistry & Molecular Biology, IU School of Medicine
    MondoA is a basic helix-loop-helix (bHLH)/leucine zipper (ZIP) transcription factor that is expressed predominantly in skeletal muscle. Studies in vitro suggest that the Max-like protein X (MondoA:Mlx) heterodimer senses the intracellular energy status and directly targets the promoter region of thioredoxin interacting protein (Txnip) and possibly glycolytic enzymes. We generated MondoA-inactivated (MondoA-/-) mice by gene targeting. MondoA-/- mice had normal body weight at birth, exhibited normal growth and appeared to be healthy. However, they exhibited unique metabolic characteristics. MondoA-/- mice built up serum lactate and alanine levels and utilized fatty acids for fuel during exercise. Gene expression and promoter analysis suggested that MondoA functionally represses peroxisome-proliferator-activated receptor γ co-activator-1α (PGC-1α)-mediated activation of pyruvate dehydrogenase kinase 4 (PDK-4) transcription. PDK4 normally down-regulates the activity of pyruvate dehydrogenase, an enzyme complex that catalyses the decarboxylation of pyruvate to acetyl-CoA for entry into the Krebs cycle; in the absence of MondoA, pyruvate is diverted towards lactate and alanine, both products of glycolysis. Dynamic testing revealed that MondoA-/- mice excel in sprinting as their skeletal muscles display an enhanced glycolytic capacity. Our studies uncover a hitherto unappreciated function of MondoA in fuel selection in vivo. Lack of MondoA results in enhanced exercise capacity with sprinting.
  • Thumbnail Image
    Item
    PDK4 drives metabolic alterations and muscle atrophy in cancer cachexia
    (Wiley, 2019-06) Pin, Fabrizio; Novinger, Leah J.; Huot, Joshua R.; Harris, Robert A.; Couch, Marion E.; O'Connell, Thomas M.; Bonetto, Andrea; Anatomy and Cell Biology, School of Medicine
    Cachexia is frequently accompanied by severe metabolic derangements, although the mechanisms responsible for this debilitating condition remain unclear. Pyruvate dehydrogenase kinase (PDK)4, a critical regulator of cellular energetic metabolism, was found elevated in experimental models of cancer, starvation, diabetes, and sepsis. Here we aimed to investigate the link between PDK4 and the changes in muscle size in cancer cachexia. High PDK4 and abnormal energetic metabolism were found in the skeletal muscle of colon-26 tumor hosts, as well as in mice fed a diet enriched in Pirinixic acid, previously shown to increase PDK4 levels. Viral-mediated PDK4 overexpression in myotube cultures was sufficient to promote myofiber shrinkage, consistent with enhanced protein catabolism and mitochondrial abnormalities. On the contrary, blockade of PDK4 was sufficient to restore myotube size in C2C12 cultures exposed to tumor media. Our data support, for the first time, a direct role for PDK4 in promoting cancer-associated muscle metabolic alterations and skeletal muscle atrophy.
  • Thumbnail Image
    Item
    Restoring cellular energetics promotes axon regeneration and functional recovery after spinal cord injury
    (Cell Press, 2020-03-03) Han, Qi; Xie, Yuxiang; Ordaz, Josue D.; Huh, Andrew J.; Huang, Ning; Wu, Wei; Liu, Naikui; Chamberlain, Kelly A.; Sheng, Zu-Hang; Xu, Xiao-Ming; Neurological Surgery, School of Medicine
    Axonal regeneration in the central nervous system (CNS) is a highly energy-demanding process. Extrinsic insults and intrinsic restrictions lead to an energy crisis in injured axons, raising the question of whether recovering energy deficits facilitates regeneration. Here, we reveal that enhancing axonal mitochondrial transport by deleting syntaphilin (Snph) recovers injury-induced mitochondrial depolarization. Using three CNS injury mouse models, we demonstrate that Snph-/- mice display enhanced corticospinal tract (CST) regeneration passing through a spinal cord lesion, accelerated regrowth of monoaminergic axons across a transection gap, and increased compensatory sprouting of uninjured CST. Notably, regenerated CST axons form functional synapses and promote motor functional recovery. Administration of the bioenergetic compound creatine boosts CST regenerative capacity in Snph-/- mice. Our study provides mechanistic insights into intrinsic regeneration failure in CNS and suggests that enhancing mitochondrial transport and cellular energetics are promising strategies to promote regeneration and functional restoration after CNS injuries.
  • Thumbnail Image
    Item
    Rheumatoid arthritis T cell and muscle oxidative metabolism associate with exercise-induced changes in cardiorespiratory fitness
    (Springer Nature, 2022-05-06) Andonian, Brian J.; Koss, Alec; Koves, Timothy R.; Hauser, Elizabeth R.; Hubal, Monica J.; Pober, David M.; Lord, Janet M.; MacIver, Nancie J.; St. Clair, E. William; Muoio, Deborah M.; Kraus, William E.; Bartlett, David B.; Huffman, Kim M.; Kinesiology, School of Health and Human Sciences
    Rheumatoid arthritis (RA) T cells drive autoimmune features via metabolic reprogramming that reduces oxidative metabolism. Exercise training improves cardiorespiratory fitness (i.e., systemic oxidative metabolism) and thus may impact RA T cell oxidative metabolic function. In this pilot study of RA participants, we took advantage of heterogeneous responses to a high-intensity interval training (HIIT) exercise program to identify relationships between improvements in cardiorespiratory fitness with changes in peripheral T cell and skeletal muscle oxidative metabolism. In 12 previously sedentary persons with seropositive RA, maximal cardiopulmonary exercise tests, fasting blood, and vastus lateralis biopsies were obtained before and after 10 weeks of HIIT. Following HIIT, improvements in RA cardiorespiratory fitness were associated with changes in RA CD4 + T cell basal and maximal respiration and skeletal muscle carnitine acetyltransferase (CrAT) enzyme activity. Further, changes in CD4 + T cell respiration were associated with changes in naïve CD4 + CCR7 + CD45RA + T cells, muscle CrAT, and muscle medium-chain acylcarnitines and fat oxidation gene expression profiles. In summary, modulation of cardiorespiratory fitness and molecular markers of skeletal muscle oxidative metabolism during exercise training paralleled changes in T cell metabolism. Exercise training that improves RA cardiorespiratory fitness may therefore be valuable in managing pathologically related immune and muscle dysfunction.
  • Thumbnail Image
    Item
    The Deterrence of Rapid Metabolic Decline Within 3 Months After Teplizumab Treatment in Individuals at High Risk for Type 1 Diabetes
    (American Diabetes Association, 2021) Sims, Emily K.; Cuthbertson, David; Herold, Kevan C.; Sosenko, Jay M.; Pediatrics, School of Medicine
    End points that provide an early identification of treatment effects are needed to implement type 1 diabetes prevention trials more efficiently. To this end, we assessed whether metabolic end points can be used to detect a teplizumab effect on rapid β-cell decline within 3 months after treatment in high-risk individuals in the TrialNet teplizumab trial. Glucose and C-peptide response curves (GCRCs) were constructed by plotting mean glucose and C-peptide values from 2-h oral glucose tolerance tests on a two-dimensional grid. Groups were compared visually for changes in GCRC shape and movement. GCRC changes reflected marked metabolic deterioration in the placebo group within 3 months of randomization. By 6 months, GCRCs resembled typical GCRCs at diagnosis. In contrast, GCRC changes in the teplizumab group suggested metabolic improvement. Quantitative comparisons, including two novel metabolic end points that indicate GCRC changes, the within-quadrant end point and the ordinal directional end point, were consistent with visual impressions of an appreciable treatment effect at the 3- and 6-month time points. In conclusion, an analytic approach combining visual evidence with novel end points demonstrated that teplizumab delays rapid metabolic decline and improves the metabolic state within 3 months after treatment; this effect extends for at least 6 months.