scholarly journals Anaplerotic pathways in Halomonas elongata: the role of the sodium gradient

2020 ◽  
Author(s):  
Karina Hobmeier ◽  
Marie C. Goëss ◽  
Christiana Sehr ◽  
Hans Jörg Kunte ◽  
Andreas Kremling ◽  
...  
Keyword(s):  
Tca Cycle ◽  
Compatible Solute ◽  
Metabolic Demand ◽  
Biotechnological Production ◽  
Biochemical Basis ◽  
Sodium Gradient ◽  
Halomonas Elongata ◽  
Anaplerotic Reactions

AbstractSalt tolerance in the γ-proteobacterium Halomonas elongata is linked to its ability to produce the compatible solute ectoine. The metabolism of ectoine production is of great interest since it can shed light on the biochemical basis of halotolerance as well as pave the way for the improvement of the biotechnological production of such compatible solute. The ectoine production pathway uses oxaloacetate as a precursor, thereby connecting ectoine production to the anaplerotic reactions that refill carbon into the TCA cycle. This places a high demand on these reactions and creates the need to regulate them not only in response to growth but also in response to extracellular salt concentration. In this work we combine modeling and experiments to analyze how these different needs shape the anaplerotic reactions in H. elongata. First, the stoichiometric and thermodynamic factors that condition the flux distributions are analyzed, then the optimal patterns of operation for oxaloacetate production are calculated. Finally, the phenotype of two deletion mutants lacking potentially relevant anaplerotic enzymes: Phosphoenolpyruvate carboxylase (Ppc) and Oxaloacetate decarboxylase (Oad) is experimentally characterized. The results show that the anaplerotic reactions in H. elongata are indeed subject to different evolutionary pressures than those of other gram-negative bacteria. Ectoine producing halophiles must meet a higher metabolic demand for oxaloacetate and the reliance of many marine bacteria on the Entner-Doudoroff pathway compromises the anaplerotic efficiency of Ppc, which is usually one of the main enzymes fulfilling this role. The anaplerotic flux in H. elongata is contributed not only by Ppc but also by Oad, an enzyme that has not yet been shown to play this role in vivo. Ppc is necessary for H. elongata to grow normally at low salt concentrations but it is not required to achieve near maximal growth rates as long as there is a steep sodium gradient. On the other hand, the lack of Oad presents serious difficulties to grow at high salt concentrations. This points to a shared role of these two enzymes in guaranteeing the supply of OAA for biosynthetic reactions.

scholarly journals MPC1 Deficiency Promotes CRC Liver Metastasis via Facilitating Nuclear Translocation of β-Catenin

2020 ◽  
Vol 2020 ◽  
pp. 1-11
Author(s):  
Guang-Ang Tian ◽  
Chun-Jie Xu ◽  
Kai-Xia Zhou ◽  
Zhi-Gang Zhang ◽  
Jian-Ren Gu ◽  
...  
Keyword(s):  
Tumor Metastasis ◽  
Nuclear Translocation ◽  
Tca Cycle ◽  
Mitochondrial Pyruvate Carrier ◽  
Human Sample ◽  
Metastatic Capacity ◽  
Tcga Dataset

Accumulating evidence has pointed out that metastasis is the leading cause of death in several malignant tumor, including CRC. During CRC, metastatic capacity is closely correlated with reprogrammed energy metabolism. Mitochondrial Pyruvate Carrier 1 (MPC1), as the carrier of transporting pyruvate into mitochondria, linked the glycolysis and TCA cycle, which would affect the energy production. However, the specific role of MPC1 on tumor metastasis in CRC remains unexplored. Here, by data mining of genes involved in pyruvate metabolism using the TCGA dataset, we found that MPC1 was significantly downregulated in CRC compared to nontumor tissues. Similar MPC1 expression pattern was also found in multiple GEO datasets. IHC staining in both human sample and AOM/DSS induced mouse CRC model revealed significant downregulation of MPC1. What is more, we found that MPC1 expression was gradually decreased in normal tissue, primary CRC, and metastasis CRC. Additionally, poor prognosis emerged in the MPC1 low expression patients, especially in patients with metastasis. Following, functional tests showed that MPC1 overexpression inhibited the motility of CRC cells in vitro and MPC1 silencing enhanced liver metastases in vivo. Furthermore, we uncovered that decreased MPC1 activated the Wnt/β-catenin pathway by promoting nuclear translocation of β-catenin to mediate the expression of MMP7, E-cadherin, Snail1, and myc. Collectively, our data suggest that MPC1 has the potential to be served as a promising biomarker for diagnosis and a therapeutic target in CRC.

scholarly journals Hepatic triglyceride contents are genetically determined in mice: results of a strain survey

2005 ◽  
Vol 288 (6) ◽  
pp. G1179-G1189 ◽  
Author(s):  
Xiaobo Lin ◽  
Pin Yue ◽  
Zhouji Chen ◽  
Gustav Schonfeld
Keyword(s):  
Tolerance Test ◽  
Biochemical Basis ◽  
Glucose Levels ◽  
Oxidation Rates ◽  
Males And Females ◽  
The One ◽  
Genetically Determined ◽  
Strain Dependent

To assess whether genetic factor(s) determine liver triglyceride (TG) levels, a 10-mouse strain survey of liver TG contents was performed. Hepatic TG contents were highest in BALB/cByJ, medium in C57BL/6J, and lowest in SWR/J in both genders. Ninety and seventy-six percent of variance in hepatic TG in males and females, respectively, was due to strain (genetic) effects. To understand the physiological/biochemical basis for differences in hepatic TG among the three strains, studies were performed in males of the BALB/cByJ, C57BL/6J, and SWR/J strains. In vivo hepatic fatty acid (FA) synthesis rates and hepatic TG secretion rates ranked BALB/cByJ ≈ C57BL/6J > SWR/J. Hepatic 1-14C-labeled palmitate oxidation rates and plasma β-hydroxybutyrate concentrations ranked in reverse order: SWR/J > BALB/cByJ ≈ C57BL/6J. After 14 h of fasting, plasma-free FA and hepatic TG contents rose most in BALB/cByJ and least in SWR/J. β-Hydroxybutyrate concentrations rose least in BALB/cByJ and most in SWR/J. Adaptation to fasting was most effective in SWR/J and least in BALB/cByJ, perhaps because BALB/cByJ are known to be deficient in SCAD, a short-chain FA oxidizing enzyme. To assess the role of insulin action, glucose tolerance test (GTT) was performed. GTT-glucose levels ranked C57BL/6J > BALB/cByJ ≈ SWR/J. Thus strain-dependent (genetic) factors play a major role in setting hepatic TG levels in mice. Processes such as FA production and hepatic export in VLDL on the one hand and FA oxidation on the other, explain some of the strain-related differences in hepatic TG contents. Additional factor(s) in the development of fatty liver in BALB/cByJ remain to be demonstrated.

scholarly journals Anaplerotic Pathways in Halomonas elongata: The Role of the Sodium Gradient

2020 ◽  
Vol 11 ◽  
Author(s):  
Karina Hobmeier ◽  
Marie C. Goëss ◽  
Christiana Sehr ◽  
Sebastian Schwaminger ◽  
Sonja Berensmeier ◽  
...  
Keyword(s):  
Sodium Gradient ◽  
Halomonas Elongata

Role of ET-1 in the regulation of coronary circulation

2003 ◽  
Vol 81 (6) ◽  
pp. 570-577 ◽  
Author(s):  
Michel Lavallée ◽  
Eric Thorin
Keyword(s):  
Coronary Vessels ◽  
Receptor Activation ◽  
Primary Objective ◽  
No Production ◽  
Metabolic Demand ◽  
Resistance Vessels ◽  
Secondary Phenomenon

Given that circulating ET levels in heart failure, in particular, may reach physiological threshold for coronary constrictor responses, the primary objective of the present review is to consider coronary vessels as an important target for circulating and locally produced endothelin(s). In healthy vessels, ET-1 causes biphasic coronary responses characterized by a transient dilation of large and small arteries followed by a sustained constriction. ETB receptors are pivotal in the early dilation of resistance vessels, whereas dilation of conductance vessels may be a secondary phenomenon triggered by flow increases. Exogenous ET-1 causes coronary constriction almost exclusively through ETA receptor activation. Human and canine large epicardial coronary vessels display significant baseline ET-1 dependent tone in vitro and in vivo, an ETA-dependent process. In contrast, ETB receptors located on smooth muscle cells are apparently less important for producing constrictor responses. NO production may serve as an important counter-regulatory mechanism to limit ET-dependent effects on coronary vessels. Conversely, in a dysfunctional endothelium, the loss of NO may augment ET-1 production and activity. By lifting the ET-dependent burden from coronary vessels, ET receptor blockade should help to ensure a closer match between cardiac metabolic demand and coronary perfusion.Key words: endothelin, ET receptors, coronary vessels, coronary blood flow, nitric oxide, shear stress, atherosclerosis, humans, animals.

scholarly journals Rapid metabolic and bioenergetic adaptations of astrocytes under hyperammonemia – a novel perspective on hepatic encephalopathy

2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Marcel Zimmermann ◽  
Andreas S. Reichert
Keyword(s):  
Hepatic Encephalopathy ◽  
Molecular Mechanisms ◽  
Tca Cycle ◽  
Therapeutic Strategies ◽  
Cellular Processes ◽  
Cellular Models ◽  
The Tca Cycle ◽  
Underlying Mechanisms

Abstract Hepatic encephalopathy (HE) is a well-studied, neurological syndrome caused by liver dysfunctions. Ammonia, the major toxin during HE pathogenesis, impairs many cellular processes within astrocytes. Yet, the molecular mechanisms causing HE are not fully understood. Here we will recapitulate possible underlying mechanisms with a clear focus on studies revealing a link between altered energy metabolism and HE in cellular models and in vivo. The role of the mitochondrial glutamate dehydrogenase and its role in metabolic rewiring of the TCA cycle will be discussed. We propose an updated model of ammonia-induced toxicity that may also be exploited for therapeutic strategies in the future.

scholarly journals The hexokinase ″HKDC1″ interaction with the mitochondria is essential for hepatocellular carcinoma progression

2021 ◽  
Author(s):  
Md. Wasim Khan ◽  
Alexander Terry ◽  
Medha Priyadarshini ◽  
Grace Guzman ◽  
Jose Cordoba-Chacon ◽  
...  
Keyword(s):  
Hepatocellular Carcinoma ◽  
Mitochondrial Dysfunction ◽  
Tca Cycle ◽  
Metabolic Reprogramming ◽  
Selective Approach ◽  
Glucose Flux ◽  
The Tca Cycle

Hepatocellular carcinoma (HCC) is a leading cause of death from cancer malignancies. Recently, hexokinase domain containing 1 (HKDC1), was shown to have significant overexpression in HCC compared to healthy tissue. Using in vitro and in vivo tools, we examined the role of HKDC1 in HCC progression. Importantly, HKDC1 ablation stops HCC progression by promoting metabolic reprogramming by shifting glucose flux away from the TCA cycle. Next, HKDC1 ablation leads to mitochondrial dysfunction resulting in less cellular energy which cannot be compensated by enhanced glucose uptake. And finally, we show that the interaction of HKDC1 with the mitochondria is essential for its role in HCC progression, and without this mitochondrial interaction mitochondrial dysfunction occurs. In sum, HKDC1 is highly expressed in HCC cells compared to normal hepatocytes, therefore targeting HKDC1, specifically its interaction with the mitochondria, reveals a highly selective approach to target cancer cells in HCC.

Metabolic regulation of coronary vascular tone: role of endothelin-1

2002 ◽  
Vol 283 (5) ◽  
pp. H1915-H1921 ◽  
Author(s):  
Daphne Merkus ◽  
Dirk J. Duncker ◽  
William M. Chilian
Keyword(s):  
Metabolic Regulation ◽  
Vascular Tone ◽  
Metabolic Demand ◽  
Coronary Vasodilation ◽  
Coronary Vascular Tone ◽  
Before And After ◽  
Rat Myocytes ◽  
Coronary Tone

Coronary tone is determined by a balance between endogenously produced endothelin and metabolic dilators. We hypothesized that coronary vasodilation during augmented metabolism is the net result of decreased endothelin production and increased production of vasodilators. Isolated rat myocytes were stimulated at 0, 200, and 400 beats/min to modify metabolism. Supernatant from these preparations was added to isolated coronary arterioles with and without blocking vasoactive pathways (adenosine, bradykinin, and endothelin). Chronically instrumented swine were studied while resting and running on a treadmill before and after endothelin type A (ETA) receptor blockade. The vasodilatory properties of the supernatant increased with increased stimulation frequencies. Combined blockade of adenosine and bradykinin receptors abolished vasodilation in response to supernatant of stimulated myocytes. ETA blockade increased vasodilation to supernatant of unstimulated myocytes but did not affect dilation to supernatant of myocytes stimulated at 400 beats/min. In vivo, ETA blockade resulted in coronary vasodilation at rest, which waned during exercise. Thus endothelin has a tonic constrictor influence through the ETA receptor at low myocardial metabolic demand but its influence decreased during increased metabolism.

scholarly journals Mitochondrial Complex II in Intestinal Epithelial Cells Is a Critical Metabolic Checkpoint That Regulates Severity of Gastrointestinal Graft-Versus-Host Disease

Blood ◽  
2019 ◽  
Vol 134 (Supplement_1) ◽  
pp. 584-584
Author(s):  
Hideaki Fujiwara ◽  
Anna V Mathew ◽  
Ilya Kovalenko ◽  
Pal Anupama ◽  
Dan Peltier ◽  
...  
Keyword(s):  
T Cells ◽  
T Cell ◽  
Graft Versus Host Disease ◽  
Checkpoint Inhibitor ◽  
Tca Cycle ◽  
Intestinal Epithelial ◽  
Graft Versus Host ◽  
Blinded Manner

Recent studies have examined the role of metabolism in pathogenic T cells in various diseases. The metabolic and bioenergetic characteristics of cells targeted by pathogenic T cells, such as gastrointestinal (GI) epithelial cells during immune-mediated disease processes are not known. Herein we explored the role of intestinal epithelial cell (IEC) metabolism on the severity of T cell mediated colitis including graft-versus-host disease (GVHD). We first determined the bioenergetics of IECs following allogeneic hematopoietic cell transplantation (HCT). We utilized the well-characterized MHC disparate BALB/c→B6 GVHD model. Recipient B6 mice were lethally irradiated (10Gy), transplanted with 5×106 BM and 3x106 splenic T cells from either syngeneic B6 or allogeneic BALB/c donors. CD326+ IECs from recipient animals were harvested on day 7 and 21 post-HCT and assessed for their bioenegetics utilizing the Seahorse analyzer. The allogeneic IECs (allo-IECs) demonstrated dramatically reduced oxygen consumption rates (OCR) but similar extracellular acidification rates (ECAR), and increased OCR/ECAR ratios compared with syngeneic IECs (syn-IECs) (OCR; 44.70 vs 110 pmol/min, P<0.0001, ECAR; 34.43 vs 40.72 mpH/min, P=0.1832, OCR/ECAR; 1.12 vs 2.836, P<0.01). Because these data indicated profound defects in mitochondrial oxidative pathways, we next profiled mitochondrial tricarboxylic acid (TCA) cycle metabolite composition in IECs and kidney (as non-GVHD controls) harvested from naïve, syngeneic and allogeneic animals (day 7 and 21 post-HCT) in an unbiased and blinded manner with gas chromatography-mass spectrometry (GC-MS). Among the TCA cycle metabolites, only succinate significantly increased in IECs, but not kidneys, from allogeneic recipients (25.6 ± 5.65vs 0.00µM/µg protein, P<0.05). To determine the reasons for high levels of succinate, we next performed metabolic flux studies with 13C-glucose and 13C-glutamine, and found that the increased succinate levels were not secondary to anaplerosis. We therefore next hypothesized that the accumulated succinate in IECs was from reduced succinate dehydrogenase A (SDHA), a component of mitochondria complex II (MC II), that converts succinate to fumarate. Consistent with this hypothesis, SDHA was significantly decreased in allo-IECs compared to syn-IECs (P<0.05), which was additionally validated in a blinded manner by immunofluorescence (Figure), immunohistochemistry and immuno-gold staining of mitochondria by electron microscopy. Analysis of IECs harvested from recipients following non-irradiated B6→B6D2F1, chemotherapy conditioned BALB/c→B6, and irradiated MHC matched mHA mismatched C3H.SW→B6 GVHD models, as well as in a CD4+CD45RBhigh T-cell→RAG1−/− model of inflammatory bowel disease (IBD), and an anti-CTLA-4 antibody augmented DSS colitis model (checkpoint-inhibitor colitis), all demonstrated reduction of MC II, SDHA, and an increase in the level of succinate. We next explored the in vivo functional relevance of SDHA in GI GVHD utilizing multiple approaches. Specifically, when Sdhaf1−/− B6 (30% of SDHA activity, P<0.01), bone marrow chimera (WT B6→Sdhaf1−/−, P<0.05) or WT animals treated with multiple chemical SDH inhibitors from day 0 to 21 post allo-HCT (itaconate; 2.5g/kg, P<0.0001, malonate; 5g/kg, P<0.001 or Atpenin A5; 9µg/kg, P<0.05) were used as recipients, all demonstrated significantly greater GI GVHD and mortality compared with allo-control animals. We furthermore generated IEC specific SDHA KO mice (villin-Cre+SDHAfl/fl), which when utilized as allogeneic recipients, they demonstrated significantly greater mortality and GI GVHD (P<0.0001). Cellular and biochemical mechanistic studies demonstrated the requirement of T cell contact with IECs, and a critical role for perforin (Prf)/ granzyme B (GB) in the breakdown and reduction of SDHA. The mechanisms for SDHA reduction were validated in vivo by transferring Prf−/− T cells into allogeneic BALB/c (GVHD) or RAG1−/−B6 (IBD) mice. Our data demonstrate that MC II component SDHA in IECs is a critical metabolic checkpoint that regulates severity of intestinal colitis caused by pathogenic allo- or auto-reactive T cells and thus provide seminal insights into GI GVHD, IBD and checkpoint-inhibitor colitis. Disclosures No relevant conflicts of interest to declare.

Mitochondrial matrix calcium ions regulate energy production in myocardium: A cytochemical study

1990 ◽  
Vol 48 (2) ◽  
pp. 166-167
Author(s):  
W.A. Jacob ◽  
R. Hertsens ◽  
A. Van Bogaert ◽  
M. De Smet
Keyword(s):  
Energy Metabolism ◽  
Calcium Ions ◽  
Energy Production ◽  
Regulation Of Respiration ◽  
Free Calcium ◽  
Mitochondrial Matrix ◽  
Cytochemical Study ◽  
Nmr Techniques

In the past most studies of the control of energy metabolism focus on the role of the phosphorylation potential ATP/ADP.Pi on the regulation of respiration. Studies using NMR techniques have demonstrated that the concentrations of these compounds for oxidation phosphorylation do not change appreciably throughout the cardiac cycle and during increases in cardiac work. Hence regulation of energy production by calcium ions, present in the mitochondrial matrix, has been the object of a number of recent studies.Three exclusively intramitochondnal dehydrogenases are key enzymes for the regulation of oxidative metabolism. They are activated by calcium ions in the low micromolar range. Since, however, earlier estimates of the intramitochondnal calcium, based on equilibrium thermodynamic considerations, were in the millimolar range, a physiological correlation was not evident. The introduction of calcium-sensitive probes fura-2 and indo-1 made monitoring of free calcium during changing energy metabolism possible. These studies were performed on isolated mitochondria and extrapolation to the in vivo situation is more or less speculative.

Meiotic CENP-C is a shepherd: bridging the space between the centromere and the kinetochore in time and space

2020 ◽  
Vol 64 (2) ◽  
pp. 251-261
Author(s):  
Jessica E. Fellmeth ◽  
Kim S. McKim
Keyword(s):  
Chromosome Segregation ◽  
New Technologies ◽  
Early Prophase ◽  
Unique Role ◽  
Kinetochore Assembly ◽  
M Phase ◽  
In Vivo Analysis ◽  
Meiosis I

Abstract While many of the proteins involved in the mitotic centromere and kinetochore are conserved in meiosis, they often gain a novel function due to the unique needs of homolog segregation during meiosis I (MI). CENP-C is a critical component of the centromere for kinetochore assembly in mitosis. Recent work, however, has highlighted the unique features of meiotic CENP-C. Centromere establishment and stability require CENP-C loading at the centromere for CENP-A function. Pre-meiotic loading of proteins necessary for homolog recombination as well as cohesion also rely on CENP-C, as do the main scaffolding components of the kinetochore. Much of this work relies on new technologies that enable in vivo analysis of meiosis like never before. Here, we strive to highlight the unique role of this highly conserved centromere protein that loads on to centromeres prior to M-phase onset, but continues to perform critical functions through chromosome segregation. CENP-C is not merely a structural link between the centromere and the kinetochore, but also a functional one joining the processes of early prophase homolog synapsis to late metaphase kinetochore assembly and signaling.

Sign in / Sign up

Export Citation Format

Share Document