scholarly journals Equilibrative Nucleoside Transporters Mediate the Import of Nicotinamide Riboside and Nicotinic Acid Riboside into Human Cells

2021 ◽  
Vol 22 (3) ◽  
pp. 1391
Author(s):  
Andrey Kropotov ◽  
Veronika Kulikova ◽  
Kirill Nerinovski ◽  
Alexander Yakimov ◽  
Maria Svetlova ◽  
...  
Keyword(s):  
Nicotinic Acid ◽  
Mammalian Cells ◽  
Experimental Models ◽  
The Body ◽  
Nucleoside Transporters ◽  
Hek293 Cells ◽  
Nucleoside Transporter ◽  
Vitamin B3 ◽  
Animal Cells ◽  
Nicotinamide Riboside

Nicotinamide riboside (NR), a new form of vitamin B3, is an effective precursor of nicotinamide adenine dinucleotide (NAD+) in human and animal cells. The introduction of NR into the body effectively increases the level of intracellular NAD+ and thereby restores physiological functions that are weakened or lost in experimental models of aging and various pathologies. Despite the active use of NR in applied biomedicine, the mechanism of its transport into mammalian cells is currently not understood. In this study, we used overexpression of proteins in HEK293 cells, and metabolite detection by NMR, to show that extracellular NR can be imported into cells by members of the equilibrative nucleoside transporter (ENT) family ENT1, ENT2, and ENT4. After being imported into cells, NR is readily metabolized resulting in Nam generation. Moreover, the same ENT-dependent mechanism can be used to import the deamidated form of NR, nicotinic acid riboside (NAR). However, NAR uptake into HEK293 cells required the stimulation of its active utilization in the cytosol such as phosphorylation by NR kinase. On the other hand, we did not detect any NR uptake mediated by the concentrative nucleoside transporters (CNT) CNT1, CNT2, or CNT3, while overexpression of CNT3, but not CNT1 or CNT2, moderately stimulated NAR utilization by HEK293 cells.

scholarly journals Degradation of Extracellular NAD+ Intermediates in Cultures of Human HEK293 Cells

Metabolites ◽  
2019 ◽  
Vol 9 (12) ◽  
pp. 293 ◽  
Author(s):  
Veronika Kulikova ◽  
Konstantin Shabalin ◽  
Kirill Nerinovski ◽  
Alexander Yakimov ◽  
Maria Svetlova ◽  
...  
Keyword(s):  
Cell Culture ◽  
Nicotinic Acid ◽  
Culture Medium ◽  
Cultured Cells ◽  
Culture Conditions ◽  
Hek293 Cells ◽  
Vitamin B3 ◽  
Serum Free ◽  
Nicotinamide Riboside ◽  
Nicotinamide Mononucleotide

Nicotinamide adenine dinucleotide (NAD) is an essential redox carrier, whereas its degradation is a key element of important signaling pathways. Human cells replenish their NAD contents through NAD biosynthesis from extracellular precursors. These precursors encompass bases nicotinamide (Nam) and nicotinic acid and their corresponding nucleosides nicotinamide riboside (NR) and nicotinic acid riboside (NAR), now collectively referred to as vitamin B3. In addition, extracellular NAD+ and nicotinamide mononucleotide (NMN), and potentially their deamidated counterparts, nicotinic acid adenine dinucleotide (NAAD) and nicotinic acid mononucleotide (NAMN), may serve as precursors of intracellular NAD. However, it is still debated whether nucleotides enter cells directly or whether they are converted to nucleosides and bases prior to uptake into cells. Here, we studied the metabolism of extracellular NAD+ and its derivatives in human HEK293 cells using normal and serum-free culture medium. Using medium containing 10% fetal bovine serum (FBS), mono- and dinucleotides were degraded to the corresponding nucleosides. In turn, the nucleosides were cleaved to their corresponding bases. Degradation was also observed in culture medium alone, in the absence of cells, indicating that FBS contains enzymatic activities which degrade NAD+ intermediates. Surprisingly, NR was also rather efficiently hydrolyzed to Nam in the absence of FBS. When cultivated in serum-free medium, HEK293 cells efficiently cleaved NAD+ and NAAD to NMN and NAMN. NMN exhibited rather high stability in cell culture, but was partially metabolized to NR. Using pharmacological inhibitors of plasma membrane transporters, we also showed that extracellular cleavage of NAD+ and NMN to NR is a prerequisite for using these nucleotides to maintain intracellular NAD contents. We also present evidence that, besides spontaneous hydrolysis, NR is intensively metabolized in cell culture by intracellular conversion to Nam. Our results demonstrate that both the cultured cells and the culture medium mediate a rather active conversion of NAD+ intermediates. Consequently, in studies of precursor supplementation and uptake, the culture conditions need to be carefully defined.

scholarly journals Nicotinamide Riboside for the Prevention and Treatment of Doxorubicin Cardiomyopathy. Opportunities and Prospects.

2021 ◽  
Author(s):  
Ekaterina Podyacheva ◽  
Yana Toropova
Keyword(s):  
High Efficiency ◽  
Experimental Models ◽  
Symptomatic Therapy ◽  
Vitamin B3 ◽  
Nicotinamide Riboside ◽  
Independent Form ◽  
Oncological Diseases ◽  
Hematological Tumors ◽  
Late Stages ◽  
Doxorubicin Cardiomyopathy

Abstract Despite the progress in the development of new anticancer strategies, cancer is rapidly spreading around the world and remains one of the most common diseases. At the same time, oncological diseases are detected in patients with late stages of the course in the overwhelming majority of cases. This fact necessitates chemotherapy both as part of a combination and in the view of an independent form of treatment. For more than 40 years, doxorubicin has been widely used in the treatment of solid and hematological tumors. At the same time, the problem of its cardiotoxicity remains unresolved, despite the high efficiency of this drug. Symptomatic therapy is used as a treatment for side-effects of doxorubicin or pathological conditions that have already appeared on their background. To date, there are no treatment methods for doxorubicin cardiomyopathy as such. A drug such as nicotinamide riboside can play an important role in solving this problem. Nicotinamide riboside is a pyridine nucleoside similar to vitamin B3 that acts as a precursor to NAD+. There are no such works in cardiomyopathy, despite the abundance of works devoted to the mechanisms of realization of the effects of nicotinamide riboside in various pathologies. The review analyzes information about the effects of NR on various experimental models of pathologies, its role in the synthesis of NAD+, and also considers the possibility and prospects of its use for the prevention of doxorubicin cardiomyopathy.

scholarly journals Substrate Dependent Regulation of the Human Equilibrative Nucleoside Transporter 1 (hENT1) in HEK293 Cells

2021 ◽  
Author(s):  
Maliha Zafar
Keyword(s):  
Plasma Membrane ◽  
Cell Sorting ◽  
Nucleoside Analog ◽  
Nucleoside Transporters ◽  
Hek293 Cells ◽  
Substrate Uptake ◽  
Nucleoside Transporter ◽  
Binding Assays ◽  
Equilibrative Nucleoside Transporter ◽  
Pre Treatment

Nucleosides and nucleoside analog drugs enter cells through nucleoside transporters, such as the human equilibrative nucleoside transporter 1 (hENT1). The regulation of nucleoside transporters is poorly understood. In this study, through fluorescence-activated cell sorting (FACS) analyses, confocal microscopy and radio-ligand binding assays, I show a decrease in hENT1 abundance at the plasma membrane (PM) in HEK cells treated in the presence of a bolus amount of cytidine (40μM) for 6 hours. Kinetic and transport assays indicate that the remaining hENT1 population at the PM has a higher Vmax and Km but there is no change in overall substrate uptake compared to untreated cells. I also show that cytidine pre-treatment leads to an increased cytotoxicity from gemcitabine (a nucleoside analog drug). These are the first data that show direct substrate dependent regulation of a nucleoside transporter by a mechanism that may involve increased recycling/internalization of the transporter.

scholarly journals Nicotinamide Riboside for the Prevention and Treatment of Doxorubicin Cardiomyopathy. Opportunities and Prospects

Nutrients ◽  
2021 ◽  
Vol 13 (10) ◽  
pp. 3435
Author(s):  
Ekaterina Podyacheva ◽  
Yana Toropova
Keyword(s):  
High Efficiency ◽  
Experimental Models ◽  
Symptomatic Therapy ◽  
Vitamin B3 ◽  
Nicotinamide Riboside ◽  
Pathological Conditions ◽  
The World ◽  
Hematological Tumors ◽  
Published Research ◽  
Doxorubicin Cardiomyopathy

Despite the progress in the development of new anticancer strategies, cancer is rapidly spreading around the world and remains one of the most common diseases. For more than 40 years, doxorubicin has been widely used in the treatment of solid and hematological tumors. At the same time, the problem of its cardiotoxicity remains unresolved, despite the high efficiency of this drug. Symptomatic therapy is used as a treatment for side-effects of doxorubicin or pathological conditions that have already appeared in their background. To date, there are no treatment methods for doxorubicin cardiomyopathy as such. A drug such as nicotinamide riboside can play an important role in solving this problem. Nicotinamide riboside is a pyridine nucleoside similar to vitamin B3 that acts as a precursor to NAD+. There is no published research on nicotinamide riboside effects on cardiomyopathy, despite the abundance of works devoted to the mechanisms of its effects in various pathologies. The review analyzes information about the effects of nicotinamide riboside on various experimental models of pathologies, its role in the synthesis of NAD+, and also considers the possibility and prospects of its use for the prevention of doxorubicin cardiomyopathy.

scholarly journals Uptake of Nitrobenzylthioinosine and Purine β-l-Nucleosides by Intracellular Toxoplasma gondii

2003 ◽  
Vol 47 (10) ◽  
pp. 3247-3251 ◽  
Author(s):  
Omar N. Al Safarjalani ◽  
Fardos N. M. Naguib ◽  
Mahmoud H. el Kouni
Keyword(s):  
Toxoplasma Gondii ◽  
Mammalian Cells ◽  
Nucleoside Transporters ◽  
Host Cells ◽  
Purine Nucleoside ◽  
Nucleoside Transport ◽  
Fibroblast Cells ◽  
Nucleoside Transporter ◽  
Intracellular Parasites ◽  
Infected Cells

ABSTRACT Intracellular Toxoplasma gondii grown in human foreskin fibroblast cells transported nitrobenzylthioinosine {NBMPR; 6-[(4-nitrobenzyl)mercapto]-9-β-d-ribofuranosylpurine}, an inhibitor of nucleoside transport in mammalian cells, as well as the nonphysiological β-l-enantiomers of purine nucleosides, β-l-adenosine, β-l-deoxyadenosine, and β-l-guanosine. The β-l-pyrimidine nucleosides, β-l-uridine, β-l-cytidine, and β-l-thymidine, were not transported. The uptake of NBMPR and the nonphysiological purine nucleoside β-l-enantiomers by the intracellular parasites also implies that Toxoplasma-infected cells can transport these nucleosides. In sharp contrast, under the same conditions, uninfected fibroblast cells did not transport NBMPR or any of the unnatural β-l-nucleosides. β-d-Adenosine and dipyridamole, another inhibitor of nucleoside transport, inhibited the uptake of NBMPR and β-l-stereoisomers of the purine nucleosides by intracellular Toxoplasma and Toxoplasma-infected cells. Furthermore, infection with a Toxoplasma mutant deficient in parasite adenosine/purine nucleoside transport reduced or abolished the uptake of β-d-adenosine, NBMPR, and purine β-l-nucleosides. Hence, the presence of the Toxoplasma adenosine/purine nucleoside transporters is apparently essential for the uptake of NBMPR and purine β-l-nucleosides by intracellular Toxoplasma and Toxoplasma-infected cells. These results also demonstrate that, in contrast to the mammalian nucleoside transporters, the Toxoplasma adenosine/purine nucleoside transporter(s) lacks stereospecificity and substrate specificity in the transport of purine nucleosides. In addition, infection with T. gondii confers the properties of the parasite's purine nucleoside transport on the parasitized host cells and enables the infected cells to transport purine nucleosides that were not transported by uninfected cells. These unique characteristics of purine nucleoside transport in T. gondii may aid in the identification of new promising antitoxoplasmic drugs.

scholarly journals Substrate Dependent Regulation of the Human Equilibrative Nucleoside Transporter 1 (hENT1) in HEK293 Cells

2021 ◽  
Author(s):  
Maliha Zafar
Keyword(s):  
Plasma Membrane ◽  
Cell Sorting ◽  
Nucleoside Analog ◽  
Nucleoside Transporters ◽  
Hek293 Cells ◽  
Substrate Uptake ◽  
Nucleoside Transporter ◽  
Binding Assays ◽  
Equilibrative Nucleoside Transporter ◽  
Pre Treatment

Nucleosides and nucleoside analog drugs enter cells through nucleoside transporters, such as the human equilibrative nucleoside transporter 1 (hENT1). The regulation of nucleoside transporters is poorly understood. In this study, through fluorescence-activated cell sorting (FACS) analyses, confocal microscopy and radio-ligand binding assays, I show a decrease in hENT1 abundance at the plasma membrane (PM) in HEK cells treated in the presence of a bolus amount of cytidine (40μM) for 6 hours. Kinetic and transport assays indicate that the remaining hENT1 population at the PM has a higher Vmax and Km but there is no change in overall substrate uptake compared to untreated cells. I also show that cytidine pre-treatment leads to an increased cytotoxicity from gemcitabine (a nucleoside analog drug). These are the first data that show direct substrate dependent regulation of a nucleoside transporter by a mechanism that may involve increased recycling/internalization of the transporter.

scholarly journals Recent advances in studies on biochemical and structural properties of equilibrative and concentrative nucleoside transporters.

2005 ◽  
Vol 52 (4) ◽  
pp. 749-758 ◽  
Author(s):  
Marzena Podgorska ◽  
Katarzyna Kocbuch ◽  
Tadeusz Pawelczyk
Keyword(s):  
Mammalian Cells ◽  
Cell Function ◽  
De Novo ◽  
Transport Processes ◽  
Nucleoside Transporters ◽  
Membrane Topology ◽  
Nucleoside Transporter ◽  
Signalling Molecules ◽  
Physiological Processes ◽  
Carrier Mediated Transport

Nucleoside transporters (NT) facilitate the movement of nucleosides and nucleobases across cell membranes. NT-mediated transport is vital for the synthesis of nucleic acids in cells that lack de novo purine synthesis. Some nucleosides display biological activity and act as signalling molecules. For example, adenosine exerts a potent action on many physiological processes including vasodilatation, hormone and neurotransmitter release, platelet aggregation, and lipolysis. Therefore, carrier-mediated transport of this nucleoside plays an important role in modulating cell function, because the efficiency of the transport processes determines adenosine availability to its receptors or to metabolizing enzymes. Nucleoside transporters are also key elements in anticancer and antiviral therapy with the use of nucleoside analogues. Mammalian cells possess two major nucleoside transporter families: equilibrative (ENT) and concentrative (CNT) Na(+)-dependent ones. This review characterizes gene loci, substrate specificity, tissue distribution, membrane topology and structure of ENT and CNT proteins. Regulation of nucleoside transporters by various factors is also presented.

scholarly journals NAD Metabolome Analysis in Human Cells Using 1H NMR Spectroscopy

2018 ◽  
Vol 19 (12) ◽  
pp. 3906 ◽  
Author(s):  
Konstantin Shabalin ◽  
Kirill Nerinovski ◽  
Alexander Yakimov ◽  
Veronika Kulikova ◽  
Maria Svetlova ◽  
...  
Keyword(s):  
Nmr Spectroscopy ◽  
Nicotinic Acid ◽  
1H Nmr ◽  
Nicotinamide Adenine Dinucleotide ◽  
1H Nmr Spectroscopy ◽  
Human Cells ◽  
Hek293 Cells ◽  
Nicotinamide Adenine ◽  
Vitamin B3 ◽  
Cell Extracts

Nicotinamide adenine dinucleotide (NAD) and its phosphorylated form, NADP, are the major coenzymes of redox reactions in central metabolic pathways. Nicotinamide adenine dinucleotide is also used to generate second messengers, such as cyclic ADP-ribose, and serves as substrate for protein modifications including ADP-ribosylation and protein deacetylation by sirtuins. The regulation of these metabolic and signaling processes depends on NAD availability. Generally, human cells accomplish their NAD supply through biosynthesis using different forms of vitamin B3: Nicotinamide (Nam) and nicotinic acid as well as nicotinamide riboside (NR) and nicotinic acid riboside (NAR). These precursors are converted to the corresponding mononucleotides NMN and NAMN, which are adenylylated to the dinucleotides NAD and NAAD, respectively. Here, we have developed an NMR-based experimental approach to detect and quantify NAD(P) and its biosynthetic intermediates in human cell extracts. Using this method, we have determined NAD, NADP, NMN and Nam pools in HEK293 cells cultivated in standard culture medium containing Nam as the only NAD precursor. When cells were grown in the additional presence of both NAR and NR, intracellular pools of deamidated NAD intermediates (NAR, NAMN and NAAD) were also detectable. We have also tested this method to quantify NAD+ in human platelets and erythrocytes. Our results demonstrate that 1H NMR spectroscopy provides a powerful method for the assessment of the cellular NAD metabolome.

scholarly journals Nicotinamide, Nicotinamide Riboside and Nicotinic Acid—Emerging Roles in Replicative and Chronological Aging in Yeast

Biomolecules ◽  
2020 ◽  
Vol 10 (4) ◽  
pp. 604
Author(s):  
Ivan Orlandi ◽  
Lilia Alberghina ◽  
Marina Vai
Keyword(s):  
Nicotinic Acid ◽  
Functional Decline ◽  
Model Systems ◽  
Vitamin B3 ◽  
Proliferating Cells ◽  
Yeast Saccharomyces Cerevisiae ◽  
Nad Metabolism ◽  
Chronological Aging ◽  
Nicotinamide Riboside ◽  
Metabolic Defects

Nicotinamide, nicotinic acid and nicotinamide riboside are vitamin B3 precursors of NAD+ in the human diet. NAD+ has a fundamental importance for cellular biology, that derives from its essential role as a cofactor of various metabolic redox reactions, as well as an obligate co-substrate for NAD+-consuming enzymes which are involved in many fundamental cellular processes including aging/longevity. During aging, a systemic decrease in NAD+ levels takes place, exposing the organism to the risk of a progressive inefficiency of those processes in which NAD+ is required and, consequently, contributing to the age-associated physiological/functional decline. In this context, dietary supplementation with NAD+ precursors is considered a promising strategy to prevent NAD+ decrease and attenuate in such a way several metabolic defects common to the aging process. The metabolism of NAD+ precursors and its impact on cell longevity have benefited greatly from studies performed in the yeast Saccharomyces cerevisiae, which is one of the most established model systems used to study the aging processes of both proliferating (replicative aging) and non-proliferating cells (chronological aging). In this review we summarize important aspects of the role played by nicotinamide, nicotinic acid and nicotinamide riboside in NAD+ metabolism and how each of these NAD+ precursors contribute to the different aspects that influence both replicative and chronological aging. Taken as a whole, the findings provided by the studies carried out in S. cerevisiae are informative for the understanding of the complex dynamic flexibility of NAD+ metabolism, which is essential for the maintenance of cellular fitness and for the development of dietary supplements based on NAD+ precursors.

scholarly journals Current Status of Putative Animal Sources of SARS-CoV-2 Infection in Humans: Wildlife, Domestic Animals and Pets

2021 ◽  
Vol 9 (4) ◽  
pp. 868
Author(s):  
Max Maurin ◽  
Florence Fenollar ◽  
Oleg Mediannikov ◽  
Bernard Davoust ◽  
Christian Devaux ◽  
...  
Keyword(s):  
Animal Species ◽  
Biological Properties ◽  
Experimental Models ◽  
Current Data ◽  
The Body ◽  
Receptor Expression ◽  
Current Status ◽  
Susceptible Animal

SARS-CoV-2 is currently considered to have emerged from a bat coronavirus reservoir. However, the real natural cycle of this virus remains to be elucidated. Moreover, the COVID-19 pandemic has led to novel opportunities for SARS-CoV-2 transmission between humans and susceptible animal species. In silico and in vitro evaluation of the interactions between the SARS-CoV-2 spike protein and eucaryotic angiotensin-converting enzyme 2 (ACE2) receptor have tentatively predicted susceptibility to SARS-CoV-2 infection of several animal species. Although useful, these data do not always correlate with in vivo data obtained in experimental models or during natural infections. Other host biological properties may intervene such as the body temperature, level of receptor expression, co-receptor, restriction factors, and genetic background. The spread of SARS-CoV-2 also depends on the extent and duration of viral shedding in the infected host as well as population density and behaviour (group living and grooming). Overall, current data indicate that the most at-risk interactions between humans and animals for COVID-19 infection are those involving certain mustelids (such as minks and ferrets), rodents (such as hamsters), lagomorphs (especially rabbits), and felines (including cats). Therefore, special attention should be paid to the risk of SARS-CoV-2 infection associated with pets.

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