Biosynthesis of long-chain (sphingoid) bases from serine by LM cells. Evidence for introduction of the 4-trans-double bond after de novo biosynthesis of N-acylsphinganine(s).

To determine the contributions of preexisting fatty acid, de novo synthesis, and chain elongation in long-chain fatty acid (LCFA) synthesis, the synthesis of LCFAs, palmitate (16:0), stearate (18:0), arachidate (20:0), behenate (22:0), and lignocerate (24:0), in the epidermis, liver, and spinal cord was determined using deuterated water and mass isotopomer distribution analysis in hairless mice and Sprague-Dawley rats. Animals were given 4% deuterated water for 5 days or 8 wk in their drinking water. Blood was withdrawn at the end of these times for the determination of deuterium enrichment, and the animals were killed to isolate the various tissues for lipid extraction for the determination of the mass isotopomer distributions. The mass isotopomer distributions in LCFA were incompatible with synthesis from a single pool of primer. The synthesis of palmitate, stearate, arachidate, behenate, and lignocerate followed the expected biochemical pathways for the synthesis of LCFAs. On average, three deuterium atoms were incorporated for every addition of an acetyl unit. The isotopomer distribution resulting from chain elongation and de novo synthesis can be described by the linear combination of two binomial distributions. The proportions of preexisting, chain elongation, and de novo-synthesized fatty acids as a percentage of the total fatty acids were determined using multiple linear regression analysis. Fractional synthesis was found to vary, depending on the tissue type and the fatty acid, from 47 to 87%. A substantial fraction (24-40%) of the newly synthesized molecules was derived from chain elongation of unlabeled (recycled) palmitate.

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Identification of 3,4-Dihydro-2H,6H-pyrimido[1,2-c][1,3]benzothiazin-6-imine Derivatives as Novel Selective Inhibitors of Plasmodium falciparum Dihydroorotate Dehydrogenase

International Journal of Molecular Sciences ◽

10.3390/ijms22137236 ◽

2021 ◽

Vol 22 (13) ◽

pp. 7236

Author(s):

Endah Dwi Hartuti ◽

Takaya Sakura ◽

Mohammed S. O. Tagod ◽

Eri Yoshida ◽

Xinying Wang ◽

...

Keyword(s):

Drug Target ◽

De Novo ◽

Dihydroorotate Dehydrogenase ◽

Chemical Library ◽

New Class ◽

De Novo Biosynthesis ◽

Starting Point ◽

Novel Drugs ◽

Low Toxicity ◽

Fourth Step

Plasmodium falciparum’s resistance to available antimalarial drugs highlights the need for the development of novel drugs. Pyrimidine de novo biosynthesis is a validated drug target for the prevention and treatment of malaria infection. P. falciparum dihydroorotate dehydrogenase (PfDHODH) catalyzes the oxidation of dihydroorotate to orotate and utilize ubiquinone as an electron acceptor in the fourth step of pyrimidine de novo biosynthesis. PfDHODH is targeted by the inhibitor DSM265, which binds to a hydrophobic pocket located at the N-terminus where ubiquinone binds, which is known to be structurally divergent from the mammalian orthologue. In this study, we screened 40,400 compounds from the Kyoto University chemical library against recombinant PfDHODH. These studies led to the identification of 3,4-dihydro-2H,6H-pyrimido[1,2-c][1,3]benzothiazin-6-imine and its derivatives as a new class of PfDHODH inhibitor. Moreover, the hit compounds identified in this study are selective for PfDHODH without inhibition of the human enzymes. Finally, this new scaffold of PfDHODH inhibitors showed growth inhibition activity against P. falciparum 3D7 with low toxicity to three human cell lines, providing a new starting point for antimalarial drug development.

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De novo Neurosteroidogenesis in Human Microglia: Involvement of the 18 kDa Translocator Protein

International Journal of Molecular Sciences ◽

10.3390/ijms22063115 ◽

2021 ◽

Vol 22 (6) ◽

pp. 3115

Author(s):

Lorenzo Germelli ◽

Eleonora Da Pozzo ◽

Chiara Giacomelli ◽

Chiara Tremolanti ◽

Laura Marchetti ◽

...

Keyword(s):

Neurotrophic Factor ◽

De Novo ◽

Neuroactive Steroids ◽

Translocator Protein ◽

Compensatory Mechanism ◽

Human Microglia ◽

De Novo Biosynthesis ◽

Murine Microglia ◽

Synthetic Ligand ◽

Tspo Expression

Neuroactive steroids are potent modulators of microglial functions and are capable of counteracting their excessive reactivity. This action has mainly been ascribed to neuroactive steroids released from other sources, as microglia have been defined unable to produce neurosteroids de novo. Unexpectedly, immortalized murine microglia recently exhibited this de novo biosynthesis; herein, de novo neurosteroidogenesis was characterized in immortalized human microglia. The results demonstrated that C20 and HMC3 microglial cells constitutively express members of the neurosteroidogenesis multiprotein machinery—in particular, the transduceosome members StAR and TSPO, and the enzyme CYP11A1. Moreover, both cell lines produce pregnenolone and transcriptionally express the enzymes involved in neurosteroidogenesis. The high TSPO expression levels observed in microglia prompted us to assess its role in de novo neurosteroidogenesis. TSPO siRNA and TSPO synthetic ligand treatments were used to reduce and prompt TSPO function, respectively. The TSPO expression downregulation compromised the de novo neurosteroidogenesis and led to an increase in StAR expression, probably as a compensatory mechanism. The pharmacological TSPO stimulation the de novo neurosteroidogenesis improved in turn the neurosteroid-mediated release of Brain-Derived Neurotrophic Factor. In conclusion, these results demonstrated that de novo neurosteroidogenesis occurs in human microglia, unravelling a new mechanism potentially useful for future therapeutic purposes.

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Synthesis, utilization, and structure of the tetrahydropterin intermediates in the bovine adrenal medullary de novo biosynthesis of tetrahydrobiopterin.

Journal of Biological Chemistry ◽

10.1016/s0021-9258(17)35846-5 ◽

1986 ◽

Vol 261 (6) ◽

pp. 2725-2737

Author(s):

G K Smith ◽

C A Nichol

Keyword(s):

De Novo ◽

De Novo Biosynthesis

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Epigenetic silencing of GTP cyclohydrolase 1 promotes hepatocellular carcinoma growth by activating superoxide anion-mediated ASK1/p38 signaling via inhibiting tetrahydrobiopterin de novo biosynthesis

Free Radical Biology and Medicine ◽

10.1016/j.freeradbiomed.2021.03.025 ◽

2021 ◽

Author(s):

Guo-Chao Zhong ◽

Zhi-Bo Zhao ◽

Yao Cheng ◽

Yun-Bing Wang ◽

Chan Qiu ◽

...

Keyword(s):

Hepatocellular Carcinoma ◽

Superoxide Anion ◽

De Novo ◽

Epigenetic Silencing ◽

Gtp Cyclohydrolase ◽

De Novo Biosynthesis

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Dietary Essential Amino Acid Restriction Promotes Hyperdipsia via Hepatic FGF21

Nutrients ◽

10.3390/nu13051469 ◽

2021 ◽

Vol 13 (5) ◽

pp. 1469

Author(s):

Patricia M. Rusu ◽

Andrea Y. Chan ◽

Mathias Heikenwalder ◽

Oliver J. Müller ◽

Adam J. Rose

Keyword(s):

Amino Acid ◽

Growth Factor ◽

Dietary Protein ◽

Essential Amino Acid ◽

De Novo ◽

Fibroblast Growth Factor 21 ◽

Fibroblast Growth ◽

De Novo Biosynthesis ◽

Dietary Requirements ◽

Dietary Amino Acid

Prior studies have reported that dietary protein dilution (DPD) or amino acid dilution promotes heightened water intake (i.e., hyperdipsia) however, the exact dietary requirements and the mechanism responsible for this effect are still unknown. Here, we show that dietary amino acid (AA) restriction is sufficient and required to drive hyperdipsia during DPD. Our studies demonstrate that particularly dietary essential AA (EAA) restriction, but not non-EAA, is responsible for the hyperdipsic effect of total dietary AA restriction (DAR). Additionally, by using diets with varying amounts of individual EAA under constant total AA supply, we demonstrate that restriction of threonine (Thr) or tryptophan (Trp) is mandatory and sufficient for the effects of DAR on hyperdipsia and that liver-derived fibroblast growth factor 21 (FGF21) is required for this hyperdipsic effect. Strikingly, artificially introducing Thr de novo biosynthesis in hepatocytes reversed hyperdipsia during DAR. In summary, our results show that the DPD effects on hyperdipsia are induced by the deprivation of Thr and Trp, and in turn, via liver/hepatocyte-derived FGF21.

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Prospective enzymes for omega-3 PUFA biosynthesis found in endoparasitic classes within the phylum Platyhelminthes

Journal of Helminthology ◽

10.1017/s0022149x20000954 ◽

2020 ◽

Vol 94 ◽

Author(s):

D. Babaran ◽

M.T. Arts ◽

R.J. Botelho ◽

S.A. Locke ◽

J. Koprivnikar

Keyword(s):

Parasite Species ◽

De Novo ◽

Genomic Data ◽

Wide Distribution ◽

Omega 3 ◽

Free Living ◽

Chain Pufa ◽

Pufa Biosynthesis ◽

Aquatic Food ◽

Long Chain

Abstract The free-living infectious stages of macroparasites, specifically, the cercariae of trematodes (flatworms), are likely to be significant (albeit underappreciated) vectors of nutritionally important polyunsaturated fatty acids (PUFA) to consumers within aquatic food webs, and other macroparasites could serve similar roles. In the context of de novo omega-3 (n-3) PUFA biosynthesis, it was thought that most animals lack the fatty acid (FA) desaturase enzymes that convert stearic acid (18:0) into ɑ-linolenic acid (ALA; 18:3n-3), the main FA precursor for n-3 long-chain PUFA. Recently, novel sequences of these enzymes were recovered from 80 species from six invertebrate phyla, with experimental confirmation of gene function in five phyla. Given this wide distribution, and the unusual attributes of flatworm genomes, we conducted an additional search for genes for de novo n-3 PUFA in the phylum Platyhelminthes. Searches with experimentally confirmed sequences from Rotifera recovered nine relevant FA desaturase sequences from eight species in four genera in the two exclusively endoparasite classes (Trematoda and Cestoda). These results could indicate adaptations of these particular parasite species, or may reflect the uneven taxonomic coverage of sequence databases. Although additional genomic data and, particularly, experimental study of gene functionality are important future validation steps, our results indicate endoparasitic platyhelminths may have enzymes for de novo n-3 PUFA biosynthesis, thereby contributing to global PUFA production, but also representing a potential target for clinical antihelmintic applications.

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