scholarly journals Carbamoyl phosphate and its substitutes for the uracil synthesis in origins of life scenarios

2021 ◽  
Author(s):  
Louis Ter-Ovanessian ◽  
Baptiste Rigaud ◽  
Alberto Mezzetti ◽  
Jean-François Lambert ◽  
Marie-Christine Maurel
Keyword(s):  
Aqueous Solutions ◽  
High Energy ◽  
Origins Of Life ◽  
Ambient Conditions ◽  
Carbamoyl Phosphate ◽  
Pyrimidine Synthesis ◽  
Cp Decomposition ◽  
Inorganic Molecules

The first step of pyrimidine synthesis along the orotate pathway is studied to test the hypothesis of geochemical continuity of protometabolic pathways at the origins of life. Carbamoyl phosphate (CP) is the first high-energy building block that intervenes in the in vivo synthesis of the uracil ring of UMP. Thus, the likelihood of its occurrence in prebiotic conditions is investigated herein. The evolution of carbamoyl phosphate in water and in ammonia aqueous solutions without enzymes was characterised using ATR-IR, 31P and 13C spectroscopies. Carbamoyl phosphate initially appears stable in water at ambient conditions before transforming to cyanate and carbamate/hydrogenocarbonate species within a matter of hours. Cyanate, less labile than CP, remains a potential carbamoylating agent. In the presence of ammonia, CP decomposition occurs more rapidly and generates urea. We conclude that CP is not a likely prebiotic reagent by itself. Alternatively, cyanate and urea may be more promising substitutes for CP, because they are both “energy-rich” (high free enthalpy molecules in aqueous solutions) and kinetically inert regarding hydrolysis. Energy-rich inorganic molecules such as trimetaphosphate or phosphoramidates were also explored for their suitability as sources of carbamoyl phosphate. Although these species did not generate CP or other carbamoylating agents, they exhibited energy transduction, specifically the formation of high-energy P-N bonds. Future efforts should aim to evaluate the role of carbamoylating agents in aspartate carbamoylation, which is the following reaction in the orotate pathway

scholarly journals Carbamoyl phosphate and its substitutes for the uracil synthesis in origins of life scenarios

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Louis M. P. Ter-Ovanessian ◽  
Baptiste Rigaud ◽  
Alberto Mezzetti ◽  
Jean-François Lambert ◽  
Marie-Christine Maurel
Keyword(s):  
Aqueous Solutions ◽  
High Energy ◽  
Origins Of Life ◽  
Ambient Conditions ◽  
Carbamoyl Phosphate ◽  
Pyrimidine Synthesis ◽  
Cp Decomposition ◽  
Inorganic Molecules

AbstractThe first step of pyrimidine synthesis along the orotate pathway is studied to test the hypothesis of geochemical continuity of protometabolic pathways at the origins of life. Carbamoyl phosphate (CP) is the first high-energy building block that intervenes in the in vivo synthesis of the uracil ring of UMP. Thus, the likelihood of its occurrence in prebiotic conditions is investigated herein. The evolution of carbamoyl phosphate in water and in ammonia aqueous solutions without enzymes was characterised using ATR-IR, 31P and 13C spectroscopies. Carbamoyl phosphate initially appears stable in water at ambient conditions before transforming to cyanate and carbamate/hydrogenocarbonate species within a matter of hours. Cyanate, less labile than CP, remains a potential carbamoylating agent. In the presence of ammonia, CP decomposition occurs more rapidly and generates urea. We conclude that CP is not a likely prebiotic reagent by itself. Alternatively, cyanate and urea may be more promising substitutes for CP, because they are both “energy-rich” (high free enthalpy molecules in aqueous solutions) and kinetically inert regarding hydrolysis. Energy-rich inorganic molecules such as trimetaphosphate or phosphoramidates were also explored for their suitability as sources of carbamoyl phosphate. Although these species did not generate CP or other carbamoylating agents, they exhibited energy transduction, specifically the formation of high-energy P–N bonds. Future efforts should aim to evaluate the role of carbamoylating agents in aspartate carbamoylation, which is the following reaction in the orotate pathway.

scholarly journals POS1388 ULTRASOUND FOR PANNICULITIS

2021 ◽  
Vol 80 (Suppl 1) ◽  
pp. 977.1-977
Author(s):  
A. Potapova ◽  
O. Egorova ◽  
O. Alekseeva ◽  
A. Volkov ◽  
S. Radenska-Lopovok
Keyword(s):  
Dynamic Range ◽  
Subcutaneous Fat ◽  
Diagnostic Value ◽  
High Energy ◽  
Contralateral Side ◽  
Imaging Method ◽  
Non Invasive ◽  
M 12

Background:Ultrasound (US) is a non-invasive and safe imaging method that allows in vivo differentiation of the morphological structures of subcutaneous fat (SCF) tissue in in normal and pathology.Objectives:Reveal features of ultrasound changes in SCF in panniculitis (Pn).Methods:57 patients (f – 45, m - 12) aged 18 - 67 years with an initial diagnosis of erythema nodosum and a disease duration of 3.6 ± 1.4 years were examined. In addition to the general clinical examination, a computed tomography of the chest organs and a pathomorphological examination of a skin biopsy from the site of the node were performed. Ultrasound was performed on a MyLabTwice apparatus (ESAOTE, Italy) using a multi-frequency linear transducer (10-18 MHz) with the PD technique, the parameters of which were adapted for recording low-speed flows (PRF 300-600 Hz, low filter, dynamic range - 20-40 dB), the presence of vascularization was assessed not only in the affected area, but also on the contralateral side using high-energy Doppler.Results:33 patients were diagnosed with septal Pn (SPn), 24 - lobular Pn (LPn). In all cases, the diagnosis was verified by histological examination. Ultrasound made it possible to assess the thickness, echoicity and vascularization of the SCF. In 35 patients, significant thickening of the SCF was revealed (as compared to the contralateral side), of which in 14 cases with SPn, in 21 - with LPn. Significant diffuse thickening of the SCF with the contralateral side was observed in 18 patients, incl. in 12 (66%) patients with LPn. Limited thickening was more typical for SPn (73%). A significant increase in the echoicity of the SCF was noted in all forms of Pn. A “lobular” echo pattern with an anechogenic environment was observed in 25 patients, of which 18 (72%) had LPn. An increase in vascularization compared to the contralateral side was recorded in 30 cases (SPn-17, LPn-13).Conclusion:The obtained preliminary results indicate the important role of ultrasound in assessing the depth and prevalence of the inflammatory process at Pn. To clarify the diagnostic value of this method, further studies are needed on a larger sample of patients.Disclosure of Interests:None declared

Ca2+ activation of heart mitochondrial oxidative phosphorylation: role of the F0/F1-ATPase

2000 ◽  
Vol 278 (2) ◽  
pp. C423-C435 ◽  
Author(s):  
Paul R. Territo ◽  
Vamsi K. Mootha ◽  
Stephanie A. French ◽  
Robert S. Balaban
Keyword(s):  
Oxidative Phosphorylation ◽  
Atp Synthesis ◽  
High Energy ◽  
Ruthenium Red ◽  
Maximal Effect ◽  
Production Rates ◽  
Atp Production ◽  
The Matrix

Ca2+ has been postulated as a cytosolic second messenger in the regulation of cardiac oxidative phosphorylation. This hypothesis draws support from the well-known effects of Ca2+ on muscle activity, which is stimulated in parallel with the Ca2+-sensitive dehydrogenases (CaDH). The effects of Ca2+ on oxidative phosphorylation were further investigated in isolated porcine heart mitochondria at the level of metabolic driving force (NADH or Δψ) and ATP production rates (flow). The resulting force-flow (F-F) relationships permitted the analysis of Ca2+ effects on several putative control points within oxidative phosphorylation, simultaneously. The F-F relationships resulting from additions of carbon substrates alone provided a model of pure CaDH activation. Comparing this curve with variable Ca2+ concentration ([Ca2+]) effects revealed an approximate twofold higher ATP production rate than could be explained by a simple increase in NADH or Δψ via CaDH activation. The half-maximal effect of Ca2+ at state 3 was 157 nM and was completely inhibited by ruthenium red (1 μM), indicating matrix dependence of the Ca2+ effect. Arsenate was used as a probe to differentiate between F0/F1-ATPase and adenylate translocase activity by a futile recycling of ADP-arsenate within the matrix, catalyzed by the F0/F1-ATPase. Ca2+increased the ADP arsenylation rate more than twofold, suggesting a direct effect on the F0/F1-ATPase. These results suggest that Ca2+ activates cardiac aerobic respiration at the level of both the CaDH and F0/F1-ATPase. This type of parallel control of both intermediary metabolism and ATP synthesis may provide a mechanism of altering ATP production rates with minimal changes in the high-energy intermediates as observed in vivo.

scholarly journals Key Enzymes in Pyrimidine Synthesis, CAD and CPS1, Predict Prognosis in Hepatocellular Carcinoma

Cancers ◽  
2021 ◽  
Vol 13 (4) ◽  
pp. 744
Author(s):  
Dirk Andreas Ridder ◽  
Mario Schindeldecker ◽  
Arndt Weinmann ◽  
Kristina Berndt ◽  
Lana Urbansky ◽  
...  
Keyword(s):  
Hepatocellular Carcinoma ◽  
Overall Survival ◽  
Cox Regression ◽  
Distant Metastases ◽  
Carbamoyl Phosphate Synthetase ◽  
Carbamoyl Phosphate ◽  
Independent Prognostic Marker ◽  
Pyrimidine Synthesis ◽  
Short Overall Survival

Patients with hepatocellular carcinoma (HCC) have a highly variable clinical course. Therefore, there is an urgent need to identify new prognostic markers to determine prognosis and select specific therapies. Recently, it has been demonstrated that dysregulation of the urea cycle (UC) is a common phenomenon in multiple types of cancer. Upon UC dysregulation, nitrogen is diverted toward the multifunctional enzyme carbamoyl-phosphate synthetase 2, aspartate transcarbamoylase, and dihydroorotase (CAD), and increases pyrimidine synthesis. In this study, we investigated the role of CAD and carbamoyl-phosphate synthetase 1 (CPS1), a rate-limiting enzyme of the UC highly expressed in hepatocytes, in HCC. We created a tissue microarray to analyze expression of both enzymes by immunohistochemistry in a large and well-characterized overall cohort of 871 HCCs of 561 patients that underwent surgery. CAD was induced in recurrent HCCs, and high expression predicted shorter overall survival. CPS1 was downregulated in HCC and further reduced in recurrent tumors and distant metastases. Additionally, low CPS1 was associated with short overall survival. A combined score of both enzymes was an independent prognostic marker in a multivariate Cox regression model (HR = 1.37, 95% confidence interval 1.06–1.75, p = 0.014). Inhibition of pyrimidine synthesis may represent a novel therapeutic strategy for HCC.

Synergistic Targeting of CHK1 and mTOR in MYC-driven tumors

2020 ◽  
Author(s):  
Xiaoxue Song ◽  
Liyuan Wang ◽  
Tianci Wang ◽  
Juncheng Hu ◽  
Jingchao Wang ◽  
...  
Keyword(s):  
De Novo ◽  
Lymphoblastic Leukemia ◽  
Cell Cycle Checkpoint ◽  
Model Systems ◽  
Carbamoyl Phosphate ◽  
M Cell ◽  
Pyrimidine Synthesis ◽  
Replicative Stress ◽  
Cycle Checkpoint

Abstract Deregulation of MYC occurs in a broad range of human cancers and often predicts poor prognosis and resistance to therapy. However, directly targeting oncogenic MYC remains unsuccessful, and indirectly inhibiting MYC emerges as a promising approach. Checkpoint kinase 1 (CHK1) is a protein kinase that coordinates the G2/M cell cycle checkpoint and protects cancer cells from excessive replicative stress. Using c-MYC-mediated T-cell acute lymphoblastic leukemia (T-ALL) and N-MYC-driven neuroblastoma as model systems, we reveal that both c-MYC and N-MYC directly bind to the CHK1 locus and activate its transcription. CHIR-124, a selective CHK1 inhibitor, impairs cell viability and induces remarkable synergistic lethality with mTOR inhibitor rapamycin in MYC-overexpressing cells. Mechanistically, rapamycin inactivates carbamoyl-phosphate synthetase 2, aspartate transcarbamoylase, and dihydroorotase (CAD), the essential enzyme for the first three steps of de novo pyrimidine synthesis, and deteriorates CHIR-124-induced replicative stress. We further demonstrate that dual treatments impede T-ALL and neuroblastoma progression in vivo. These results suggest simultaneous targeting of CHK1 and mTOR as a novel and powerful co-treatment modality for MYC-mediated tumors.

scholarly journals Mitochondrial dynamics during spermatogenesis

2020 ◽  
Vol 133 (14) ◽  
pp. jcs235937
Author(s):  
Grigor Varuzhanyan ◽  
David C. Chan
Keyword(s):  
Germ Line ◽  
Mitochondrial Dynamics ◽  
High Energy ◽  
Mitochondrial Fusion ◽  
Developmental Systems ◽  
Developmentally Regulated ◽  
Energy Demands ◽  
Normal Cellular Function

ABSTRACTMitochondrial fusion and fission (mitochondrial dynamics) are homeostatic processes that safeguard normal cellular function. This relationship is especially strong in tissues with constitutively high energy demands, such as brain, heart and skeletal muscle. Less is known about the role of mitochondrial dynamics in developmental systems that involve changes in metabolic function. One such system is spermatogenesis. The first mitochondrial dynamics gene, Fuzzy onions (Fzo), was discovered in 1997 to mediate mitochondrial fusion during Drosophila spermatogenesis. In mammals, however, the role of mitochondrial fusion during spermatogenesis remained unknown for nearly two decades after discovery of Fzo. Mammalian spermatogenesis is one of the most complex and lengthy differentiation processes in biology, transforming spermatogonial stem cells into highly specialized sperm cells over a 5-week period. This elaborate differentiation process requires several developmentally regulated mitochondrial and metabolic transitions, making it an attractive model system for studying mitochondrial dynamics in vivo. We review the emerging role of mitochondrial biology, and especially its dynamics, during the development of the male germ line.

scholarly journals Role of the glutamate dehydrogenase reaction in furnishing aspartate nitrogen for urea synthesis: studies in perfused rat liver with 15N

2003 ◽  
Vol 376 (1) ◽  
pp. 179-188 ◽  
Author(s):  
Itzhak NISSIM ◽  
Oksana HORYN ◽  
Bohdan LUHOVYY ◽  
Adam LAZAROW ◽  
Yevgeny DAIKHIN ◽  
...  
Keyword(s):  
Amino Acids ◽  
Glutamate Dehydrogenase ◽  
Reductive Amination ◽  
Liver Perfusion ◽  
Urea Synthesis ◽  
Carbamoyl Phosphate ◽  
Dehydrogenase Reaction ◽  
15N Urea

The present study was designed to determine: (i) the role of the reductive amination of α-ketoglutarate via the glutamate dehydrogenase reaction in furnishing mitochondrial glutamate and its transamination into aspartate; (ii) the relative incorporation of perfusate 15NH4Cl, [2-15N]glutamine or [5-15N]glutamine into carbamoyl phosphate and aspartate-N and, thereby, [15N]urea isotopomers; and (iii) the extent to which perfusate [15N]aspartate is taken up by the liver and incorporated into [15N]urea. We used a liver-perfusion system containing a physiological mixture of amino acids and ammonia similar to concentrations in vivo, with 15N label only in glutamine, ammonia or aspartate. The results demonstrate that in perfusions with a physiological mixture of amino acids, approx. 45 and 30% of total urea-N output was derived from perfusate ammonia and glutamine-N respectively. Approximately two-thirds of the ammonia utilized for carbamoyl phosphate synthesis was derived from perfusate ammonia and one-third from glutamine. Perfusate [2-15N]glutamine, [5-15N]glutamine or [15N]aspartate provided 24, 10 and 10% respectively of the hepatic aspartate-N pool, whereas perfusate 15NH4Cl provided approx. 37% of aspartate-N utilized for urea synthesis, secondary to the net formation of [15N]glutamate via the glutamate dehydrogenase reaction. The results suggest that the mitochondrial glutamate formed via the reductive amination of α-ketoglutarate may have a key role in ammonia detoxification by the following processes: (i) furnishing aspartate-N for ureagenesis; (ii) serving as a scavenger for excess ammonia; and (iii) improving the availability of the mitochondrial [glutamate] for synthesis of N-acetylglutamate. In addition, the current findings suggest that the formation of aspartate via the mitochondrial aspartate aminotransferase reaction may play an important role in the synthesis of cytosolic argininosuccinate.

scholarly journals STEM-22. TARGETING PYRIMIDINE SYNTHESIS ACCENTUATES MOLECULAR THERAPY RESPONSE IN GLIOBLASTOMA STEM CELLS

2019 ◽  
Vol 21 (Supplement_6) ◽  
pp. vi238-vi238
Author(s):  
Kailin Yang ◽  
Xiuxing Wang ◽  
Qiulian Wu ◽  
Leo Kim ◽  
Andrew Morton ◽  
...  
Keyword(s):  
Stem Cells ◽  
De Novo ◽  
Metabolic Reprogramming ◽  
Molecular Therapy ◽  
Driver Mutations ◽  
Carbamoyl Phosphate ◽  
Glioblastoma Stem Cells ◽  
Pyrimidine Synthesis ◽  
Pyrimidine Nucleotide

Abstract Glioblastoma stem cells (GSCs) reprogram glucose metabolism by hijacking high-affinity glucose uptake to survive in a nutritionally dynamic microenvironment. Here, we trace metabolic aberrations in GSCs to link core genetic mutations in glioblastoma to dependency on de novo pyrimidine synthesis. Targeting the pyrimidine synthetic rate-limiting step enzyme carbamoyl-phosphate synthetase 2, aspartate transcarbamyolase, dihydroorotase (CAD) or the critical downstream enzyme, dihydroorotate dehydrogenase (DHODH) inhibited GSC survival, self-renewal, and in vivo tumor initiation through the depletion of the pyrimidine nucleotide supply in rodent models. Mutations in EGFR or PTEN generated distinct CAD phosphorylation patterns to activate carbon influx through pyrimidine synthesis. Simultaneous abrogation of tumor-specific driver mutations and DHODH activity with clinically approved inhibitors demonstrated sustained inhibition of metabolic activity of pyrimidine synthesis and GSC tumorigenic capacity. Higher expression of pyrimidine synthesis genes portend poor prognosis of glioblastoma patients. Collectively, our results demonstrate a therapeutic approach of precision medicine through targeting the nexus between driver mutations and metabolic reprogramming in cancer stem cells.

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