scholarly journals Physiology-Based Kinetic Modeling of Neuronal Energy Metabolism Unravels the Molecular Basis of NAD(P)H Fluorescence Transients

2015 ◽  
Vol 35 (9) ◽  
pp. 1494-1506 ◽  
Author(s):  
Nikolaus Berndt ◽  
Oliver Kann ◽  
Hermann-Georg Holzhütter
Keyword(s):  
Energy Metabolism ◽  
Tricarboxylic Acid Cycle ◽  
Single Cells ◽  
Brain Slices ◽  
Nicotinamide Adenine Dinucleotide Phosphate ◽  
Spatial Location ◽  
Metabolic Changes ◽  
Reduced Form ◽  
Tissue Slices ◽  
Fluorescence Transients

Imaging of the cellular fluorescence of the reduced form of nicotinamide adenine dinucleotide (phosphate) (NAD(P)H) is one of the few metabolic readouts that enable noninvasive and time-resolved monitoring of the functional status of mitochondria in neuronal tissues. Stimulation-induced transient changes in NAD(P)H fluorescence intensity frequently display a biphasic characteristic that is influenced by various molecular processes, e.g., intracellular calcium dynamics, tricarboxylic acid cycle activity, the malate–aspartate shuttle, the glycerol-3-phosphate shuttle, oxygen supply or adenosine triphosphate (ATP) demand. To evaluate the relative impact of these processes, we developed and validated a detailed physiologic mathematical model of the energy metabolism of neuronal cells and used the model to simulate metabolic changes of single cells and tissue slices under different settings of stimulus-induced activity and varying nutritional supply of glucose, pyruvate or lactate. Notably, all experimentally determined NAD(P)H responses could be reproduced with one and the same generic cellular model. Our computations reveal that (1) cells with quite different metabolic status may generate almost identical NAD(P)H responses and (2) cells of the same type may quite differently contribute to aggregate NAD(P)H responses recorded in brain slices, depending on the spatial location within the tissue. Our computational approach reconciles different and sometimes even controversial experimental findings and improves our mechanistic understanding of the metabolic changes underlying live-cell NAD(P)H fluorescence transients.

scholarly journals Mitochondrial NADP(H) generation is essential for proline biosynthesis

Science ◽  
2021 ◽  
pp. eabd5491
Author(s):  
Jiajun Zhu ◽  
Simon Schwörer ◽  
Mirela Berisa ◽  
Yeon Ju Kyung ◽  
Keun Woo Ryu ◽  
...  
Keyword(s):  
Tricarboxylic Acid Cycle ◽  
Nicotinamide Adenine Dinucleotide Phosphate ◽  
Tricarboxylic Acid ◽  
Reduced Form ◽  
Growth Defect ◽  
Nad Kinase ◽  
Proline Biosynthesis ◽  
Mitochondrial Oxidative Stress ◽  
Folate Pathway ◽  
Reductive Metabolism

The coenzyme nicotinamide adenine dinucleotide phosphate (NADP+) and its reduced form (NADPH) regulate reductive metabolism in a subcellularly compartmentalized manner. Mitochondrial NADP(H) production depends on the phosphorylation of NAD(H) by NAD kinase 2 (NADK2). Deletion of NADK2 in human cell lines did not alter mitochondrial folate pathway activity, tricarboxylic acid cycle activity, or mitochondrial oxidative stress, but led to impaired cell proliferation in minimal medium. This growth defect was rescued by proline supplementation. NADK2-mediated mitochondrial NADP(H) generation was required for the reduction of glutamate and hence proline biosynthesis. Furthermore, mitochondrial NADP(H) availability determined the production of collagen proteins by cells of mesenchymal lineage. Thus, a primary function of the mitochondrial NADP(H) pool is to support proline biosynthesis for use in cytosolic protein synthesis.

scholarly journals Effects of sevoflurane anesthesia and abdominal surgery on the systemic metabolome: a prospective observational study

2021 ◽  
Vol 21 (1) ◽  
Author(s):  
Yiyong Wei ◽  
Donghang Zhang ◽  
Jin Liu ◽  
Mengchan Ou ◽  
Peng Liang ◽  
...  
Keyword(s):  
Abdominal Surgery ◽  
General Anesthesia ◽  
Tricarboxylic Acid Cycle ◽  
Tricarboxylic Acid ◽  
Metabolic Changes ◽  
Sevoflurane Anesthesia ◽  
Glutamate Metabolism ◽  
Acid Cycle ◽  
Link Type ◽  
The Mean

Abstract Background Metabolic status can be impacted by general anesthesia and surgery. However, the exact effects of general anesthesia and surgery on systemic metabolome remain unclear, which might contribute to postoperative outcomes. Methods Five hundred patients who underwent abdominal surgery were included. General anesthesia was mainly maintained with sevoflurane. The end-tidal sevoflurane concentration (ETsevo) was adjusted to maintain BIS (Bispectral index) value between 40 and 60. The mean ETsevo from 20 min after endotracheal intubation to 2 h after the beginning of surgery was calculated for each patient. The patients were further divided into low ETsevo group (mean − SD) and high ETsevo group (mean + SD) to investigate the possible metabolic changes relevant to the amount of sevoflurane exposure. Results The mean ETsevo of the 500 patients was 1.60% ± 0.34%. Patients with low ETsevo (n = 55) and high ETsevo (n = 59) were selected for metabolomic analysis (1.06% ± 0.13% vs. 2.17% ± 0.16%, P < 0.001). Sevoflurane and abdominal surgery disturbed the tricarboxylic acid cycle as identified by increased citrate and cis-aconitate levels and impacted glycometabolism as identified by increased sucrose and D-glucose levels in these 114 patients. Glutamate metabolism was also impacted by sevoflurane and abdominal surgery in all the patients. In the patients with high ETsevo, levels of L-glutamine, pyroglutamic acid, sphinganine and L-selenocysteine after sevoflurane anesthesia and abdominal surgery were significantly higher than those of the patients with low ETsevo, suggesting that these metabolic changes might be relevant to the amount of sevoflurane exposure. Conclusions Sevoflurane anesthesia and abdominal surgery can impact principal metabolic pathways in clinical patients including tricarboxylic acid cycle, glycometabolism and glutamate metabolism. This study may provide a resource data for future studies about metabolism relevant to general anaesthesia and surgeries. Trial registration www.chictr.org.cn. identifier: ChiCTR1800014327.

scholarly journals Malonyl-proteome profiles of Staphylococcus aureus reveal lysine malonylation modification in enzymes involved in energy metabolism

2021 ◽  
Vol 19 (1) ◽  
Author(s):  
Yanan Shi ◽  
Jingjing Zhu ◽  
Yan Xu ◽  
Xiaozhao Tang ◽  
Zushun Yang ◽  
...  
Keyword(s):  
Staphylococcus Aureus ◽  
Energy Metabolism ◽  
Active Sites ◽  
Current Knowledge ◽  
Tricarboxylic Acid Cycle ◽  
Protein A ◽  
Pentose Phosphate ◽  
Post Translational Modification ◽  
Bacterial Physiology ◽  
Dihydrolipoyl Dehydrogenase

Abstract Background Protein lysine malonylation, a novel post-translational modification (PTM), has been recently linked with energy metabolism in bacteria. Staphylococcus aureus is the third most important foodborne pathogen worldwide. Nonetheless, substrates and biological roles of malonylation are still poorly understood in this pathogen. Results Using anti-malonyl-lysine antibody enrichment and high-resolution LC-MS/MS analysis, 440 lysine-malonylated sites were identified in 281 proteins of S. aureus strain. The frequency of valine in position − 1 and alanine at + 2 and + 4 positions was high. KEGG pathway analysis showed that six categories were highly enriched, including ribosome, glycolysis/gluconeogenesis, pentose phosphate pathway (PPP), tricarboxylic acid cycle (TCA), valine, leucine, isoleucine degradation, and aminoacyl-tRNA biosynthesis. In total, 31 malonylated sites in S. aureus shared homology with lysine-malonylated sites previously identified in E. coli, indicating malonylated proteins are highly conserved among bacteria. Key rate-limiting enzymes in central carbon metabolic pathways were also found to be malonylated in S. aureus, namely pyruvate kinase (PYK), 6-phosphofructokinase, phosphoglycerate kinase, dihydrolipoyl dehydrogenase, and F1F0-ATP synthase. Notably, malonylation sites were found at or near protein active sites, including KH domain protein, thioredoxin, alanine dehydrogenase (ALD), dihydrolipoyl dehydrogenase (LpdA), pyruvate oxidase CidC, and catabolite control protein A (CcpA), thus suggesting that lysine malonylation may affect the activity of such enzymes. Conclusions Data presented herein expand the current knowledge on lysine malonylation in prokaryotes and indicate the potential roles of protein malonylation in bacterial physiology and metabolism.

scholarly journals Intravital microscopy imaging of kidney injury and regeneration

2021 ◽  
Vol 7 (1) ◽  
Author(s):  
Yue Liu ◽  
Zongjin Li
Keyword(s):  
Cell Fate ◽  
Intravital Microscopy ◽  
Single Cells ◽  
Elevated Serum ◽  
Kidney Injury ◽  
Lineage Tracing ◽  
Tissue Slices ◽  
Microscopy Imaging ◽  
Two Photon Microscopy ◽  
Nitrogen Levels

AbstractAcute kidney injury (AKI) is a common clinical symptom, which is mainly manifested by elevated serum creatinine and blood urea nitrogen levels. When AKI is not repaired in time, the patient is prone to develop chronic kidney disease (CKD). The kidney is composed of more than 30 different cells, and its structure is complex. It is extremely challenging to understand the lineage relationships and cell fate of these cells in the process of kidney injury and regeneration. Since the 20th century, lineage tracing technology has provided an important mean for studying organ development, tissue damage repair, and the differentiation and fate of single cells. However, traditional lineage tracing methods rely on sacrificing animals to make tissue slices and then take snapshots with conventional imaging tools to obtain interesting information. This method cannot achieve dynamic and continuous monitoring of cell actions on living animals. As a kind of intravital microscopy (IVM), two-photon microscopy (TPM) has successfully solved the above problems. Because TPM has the ability to penetrate deep tissues and can achieve imaging at the single cell level, lineage tracing technology with TPM is gradually becoming popular. In this review, we provided the key technical elements of lineage tracing, and how to use intravital imaging technology to visualize and quantify the fate of renal cells.

scholarly journals HexR Controls Glucose-Responsive Genes and Central Carbon Metabolism in Neisseria meningitidis

2015 ◽  
Vol 198 (4) ◽  
pp. 644-654 ◽  
Author(s):  
Ana Antunes ◽  
Giacomo Golfieri ◽  
Francesca Ferlicca ◽  
Marzia M. Giuliani ◽  
Vincenzo Scarlato ◽  
...  
Keyword(s):  
Energy Metabolism ◽  
Neisseria Meningitidis ◽  
Microarray Analysis ◽  
Carbon Metabolism ◽  
Tricarboxylic Acid Cycle ◽  
Transcriptional Regulator ◽  
Central Carbon Metabolism ◽  
Binding Motif ◽  
Content Type ◽  
Central Carbon

ABSTRACTNeisseria meningitidis, an exclusively human pathogen and the leading cause of bacterial meningitis, must adapt to different host niches during human infection.N. meningitidiscan utilize a restricted range of carbon sources, including lactate, glucose, and pyruvate, whose concentrations vary in host niches. Microarray analysis ofN. meningitidisgrown in a chemically defined medium in the presence or absence of glucose allowed us to identify genes regulated by carbon source availability. Most such genes are implicated in energy metabolism and transport, and some are implicated in virulence. In particular, genes involved in glucose catabolism were upregulated, whereas genes involved in the tricarboxylic acid cycle were downregulated. Several genes encoding surface-exposed proteins, including the MafA adhesins andNeisseriasurface protein A, were upregulated in the presence of glucose. Our microarray analysis led to the identification of a glucose-responsivehexR-like transcriptional regulator that controls genes of the central carbon metabolism ofN. meningitidisin response to glucose. We characterized the HexR regulon and showed that thehexRgene is accountable for some of the glucose-responsive regulation;in vitroassays with the purified protein showed that HexR binds to the promoters of the central metabolic operons of the bacterium. Based on DNA sequence alignment of the target sites, we propose a 17-bp pseudopalindromic consensus HexR binding motif. Furthermore,N. meningitidisstrains lackinghexRexpression were deficient in establishing successful bacteremia in an infant rat model of infection, indicating the importance of this regulator for the survival of this pathogenin vivo.IMPORTANCENeisseria meningitidisgrows on a limited range of nutrients during infection. We analyzed the gene expression ofN. meningitidisin response to glucose, the main energy source available in human blood, and we found that glucose regulates many genes implicated in energy metabolism and nutrient transport, as well as some implicated in virulence. We identified and characterized a transcriptional regulator (HexR) that controls metabolic genes ofN. meningitidisin response to glucose. We generated a mutant lacking HexR and found that the mutant was impaired in causing systemic infection in animal models. SinceN. meningitidislacks known bacterial regulators of energy metabolism, our findings suggest that HexR plays a major role in its biology by regulating metabolism in response to environmental signals.

STEADY STATE OXIDATION OF GLUCOSE IN THE HYPOTHYROID DIABETIC RAT: A ROLE FOR THE ADRENAL CORTEX IN GLUCOSE OXIDATION

1963 ◽  
Vol 41 (5) ◽  
pp. 1293-1305
Author(s):  
Dorothy S. Dow ◽  
C. E. Allen
Keyword(s):  
Steady State ◽  
Glucose Oxidation ◽  
Tricarboxylic Acid Cycle ◽  
Critical Factor ◽  
Inhibitory Effect ◽  
Reduced Form ◽  
Diabetic Rat ◽  
Hexose Monophosphate ◽  
Hexose Monophosphate Pathway ◽  
Oxidation Of Glucose

A steady state between the specific activities of blood glucose and expired CO2in the hypothyroid diabetic rat was maintained for extended periods of time following a single intraperitoneal injection of glucose-1-C14or glucose-6-C14. Rates of oxidation of the labelled sugars were measured during the steady state.Glucose oxidation by way of glycolysis and the tricarboxylic acid cycle in the hypothyroid diabetic rat paralleled the decrease in expired CO2but glucose oxidation by way of the hexose monophosphate pathway was completely suppressed.It is suggested that the observed inhibitory effect on the hexose monophosphate pathway is due to the maintenance of diphosphopyridine nucleotide in the reduced form as the result of goitrogen inhibition of steroid-catalyzed transhydrogenation.The results suggest that steroid concentration may be a critical factor in regulation of glucose oxidation by way of the hexose monophosphate pathway.

scholarly journals Towards Initial Indications for a Thiol-Based Redox Control of Arabidopsis 5-Aminolevulinic Acid Dehydratase

Antioxidants ◽  
2018 ◽  
Vol 7 (11) ◽  
pp. 152 ◽  
Author(s):  
Daniel Wittmann ◽  
Sigri Kløve ◽  
Peng Wang ◽  
Bernhard Grimm
Keyword(s):  
Aminolevulinic Acid ◽  
Nicotinamide Adenine Dinucleotide Phosphate ◽  
Thioredoxin Reductase ◽  
Reducing Power ◽  
Reduced Form ◽  
Redox Control ◽  
In Planta ◽  
Acid Dehydratase ◽  
Reducing Conditions ◽  
Alad Activity

Thiol-based redox control is one of the important posttranslational mechanisms of the tetrapyrrole biosynthesis pathway. Many enzymes of the pathway have been shown to interact with thioredoxin (TRX) and Nicotinamide adenine dinucleotide phosphate (NADPH)-dependent thioredoxin reductase C (NTRC). We examined the redox-dependency of 5-aminolevulinic acid dehydratase (ALAD), which catalyzed the conjugation of two 5-aminolevulinic acid (ALA) molecules to porphobilinogen. ALAD interacted with TRX f, TRX m and NTRC in chloroplasts. Consequently, less ALAD protein accumulated in the trx f1, ntrc and trx f1/ntrc mutants compared to wild-type control resulting in decreased ALAD activity. In a polyacrylamide gel under non-reducing conditions, ALAD monomers turned out to be present in reduced and two oxidized forms. The reduced and oxidized forms of ALAD differed in their catalytic activity. The addition of TRX stimulated ALAD activity. From our results it was concluded that (i) deficiency of the reducing power mainly affected the in planta stability of ALAD; and (ii) the reduced form of ALAD displayed increased enzymatic activity.

Squalene epoxidase drives NAFLD-induced hepatocellular carcinoma and is a pharmaceutical target

2018 ◽  
Vol 10 (437) ◽  
pp. eaap9840 ◽  
Author(s):  
Dabin Liu ◽  
Chi Chun Wong ◽  
Li Fu ◽  
Huarong Chen ◽  
Liuyang Zhao ◽  
...  
Keyword(s):  
Hepatocellular Carcinoma ◽  
Cell Growth ◽  
Cholesteryl Ester ◽  
Dna Methyltransferase ◽  
Nicotinamide Adenine Dinucleotide Phosphate ◽  
Reduced Form ◽  
Squalene Epoxidase ◽  
High Cholesterol Diet ◽  
Sequencing Analysis ◽  
Nonalcoholic Fatty Liver

Nonalcoholic fatty liver disease (NAFLD)–induced hepatocellular carcinoma (HCC) is an emerging malignancy in the developed world; however, mechanisms that contribute to its formation are largely unknown, and targeted therapy is currently not available. Our RNA sequencing analysis of NAFLD-HCC samples revealed squalene epoxidase (SQLE) as the top outlier metabolic gene overexpressed in NAFLD-HCC patients. Hepatocyte-specific Sqle transgenic expression in mice accelerated the development of high-fat, high-cholesterol diet–induced HCC. SQLE exerts its oncogenic effect via its metabolites, cholesteryl ester and nicotinamide adenine dinucleotide phosphate (NADP+). Increased SQLE expression promotes the biosynthesis of cholesteryl ester, which induces NAFLD-HCC cell growth. SQLE increased the NADP+/NADPH (reduced form of NADP+) ratio, which triggered a cascade of events involving oxidative stress–induced DNA methyltransferase 3A (DNMT3A) expression, DNMT3A-mediated epigenetic silencing of PTEN, and activation of AKT-mTOR (mammalian target of rapamycin). In human NAFLD-HCC and HCC, SQLE is overexpressed and its expression is associated with poor patient outcomes. Terbinafine, a U.S. Food and Drug Administration–approved antifungal drug targeting SQLE, markedly inhibited SQLE-induced NAFLD-HCC cell growth in NAFLD-HCC and HCC cells and attenuated tumor development in xenograft models and in Sqle transgenic mice. Suppression of tumor growth by terbinafine is associated with decreased cholesteryl ester concentrations, restoration of PTEN expression, and inhibition of AKT-mTOR, consistent with blockade of SQLE function. Collectively, we established SQLE as an oncogene in NAFLD-HCC and propose that repurposing SQLE inhibitors may be a promising approach for the prevention and treatment of NAFLD-HCC.

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