Niacinamide Abstracts 8

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Nicotinamide riboside promotes Sir2 silencing and extends lifespan via Nrk and Urh1/Pnp1/Meu1 pathways to NAD+.
            (Belenky et al., 2007) Download
Although NAD(+) biosynthesis is required for Sir2 functions and replicative lifespan in yeast, alterations in NAD(+) precursors have been reported to accelerate aging but not to extend lifespan. In eukaryotes, nicotinamide riboside is a newly discovered NAD(+) precursor that is converted to nicotinamide mononucleotide by specific nicotinamide riboside kinases, Nrk1 and Nrk2. In this study, we discovered that exogenous nicotinamide riboside promotes Sir2-dependent repression of recombination, improves gene silencing, and extends lifespan without calorie restriction. The mechanism of action of nicotinamide riboside is totally dependent on increased net NAD(+) synthesis through two pathways, the Nrk1 pathway and the Urh1/Pnp1/Meu1 pathway, which is Nrk1 independent. Additionally, the two nicotinamide riboside salvage pathways contribute to NAD(+) metabolism in the absence of nicotinamide-riboside supplementation. Thus, like calorie restriction in the mouse, nicotinamide riboside elevates NAD(+) and increases Sir2 function.

Activation of SIRT3 by the NAD⁺ precursor nicotinamide riboside protects from noise-induced hearing loss.
            (Brown et al., 2014) Download
Intense noise exposure causes hearing loss by inducing degeneration of spiral ganglia neurites that innervate cochlear hair cells. Nicotinamide adenine dinucleotide (NAD(+)) exhibits axon-protective effects in cultured neurons; however, its ability to block degeneration in vivo has been difficult to establish due to its poor cell permeability and serum instability. Here, we describe a strategy to increase cochlear NAD(+) levels in mice by administering nicotinamide riboside (NR), a recently described NAD(+) precursor. We find that administration of NR, even after noise exposure, prevents noise-induced hearing loss (NIHL) and spiral ganglia neurite degeneration. These effects are mediated by the NAD(+)-dependent mitochondrial sirtuin, SIRT3, since SIRT3-overexpressing mice are resistant to NIHL and SIRT3 deletion abrogates the protective effects of NR and expression of NAD(+) biosynthetic enzymes. These findings reveal that administration of NR activates a NAD(+)-SIRT3 pathway that reduces neurite degeneration caused by noise exposure.


The NAD(+) precursor nicotinamide riboside enhances oxidative metabolism and protects against high-fat diet-induced obesity.
            (Cantó et al., 2012) Download
As NAD(+) is a rate-limiting cosubstrate for the sirtuin enzymes, its modulation is emerging as a valuable tool to regulate sirtuin function and, consequently, oxidative metabolism. In line with this premise, decreased activity of PARP-1 or CD38-both NAD(+) consumers-increases NAD(+) bioavailability, resulting in SIRT1 activation and protection against metabolic disease. Here we evaluated whether similar effects could be achieved by increasing the supply of nicotinamide riboside (NR), a recently described natural NAD(+) precursor with the ability to increase NAD(+) levels, Sir2-dependent gene silencing, and replicative life span in yeast. We show that NR supplementation in mammalian cells and mouse tissues increases NAD(+) levels and activates SIRT1 and SIRT3, culminating in enhanced oxidative metabolism and protection against high-fat diet-induced metabolic abnormalities. Consequently, our results indicate that the natural vitamin NR could be used as a nutritional supplement to ameliorate metabolic and age-related disorders characterized by defective mitochondrial function.

Nicotinamide riboside restores cognition through an upregulation of proliferator-activated receptor-γ coactivator 1α regulated β-secretase 1 degradation and mitochondrial gene expression in Alzheimer's mouse models.
            (Gong et al., 2013) Download
Nicotinamide adenine dinucleotide (NAD)(+), a coenzyme involved in redox activities in the mitochondrial electron transport chain, has been identified as a key regulator of the lifespan-extending effects, and the activation of NAD(+) expression has been linked with a decrease in beta-amyloid (Aβ) toxicity in Alzheimer's disease (AD). Nicotinamide riboside (NR) is a NAD(+) precursor, it promotes peroxisome proliferator-activated receptor-γ coactivator 1 (PGC)-1α expression in the brain. Evidence has shown that PGC-1α is a crucial regulator of Aβ generation because it affects β-secretase (BACE1) degradation. In this study we tested the hypothesis that NR treatment in an AD mouse model could attenuate Aβ toxicity through the activation of PGC-1α-mediated BACE1 degradation. Using the Tg2576 AD mouse model, using in vivo behavioral analyses, biochemistry assays, small hairpin RNA (shRNA) gene silencing and electrophysiological recording, we found (1) dietary treatment of Tg2576 mice with 250 mg/kg/day of NR for 3 months significantly attenuates cognitive deterioration in Tg2576 mice and coincides with an increase in the steady-state levels of NAD(+) in the cerebral cortex; (2) application of NR to hippocampal slices (10 μM) for 4 hours abolishes the deficits in long-term potentiation recorded in the CA1 region of Tg2576 mice; (3) NR treatment promotes PGC-1α expression in the brain coinciding with enhanced degradation of BACE1 and the reduction of Aβ production in Tg2576 mice. Further in vitro studies confirmed that BACE1 protein content is decreased by NR treatment in primary neuronal cultures derived from Tg2576 embryos, in which BACE1 degradation was prevented by PGC-1α-shRNA gene silencing; and (4) NR treatment and PGC-1α overexpression enhance BACE1 ubiquitination and proteasomal degradation. Our studies suggest that dietary treatment with NR might benefit AD cognitive function and synaptic plasticity, in part by promoting PGC-1α-mediated BACE1 ubiquitination and degradation, thus preventing Aβ production in the brain.

Topical nicotinamide for seborrheic dermatitis: an open randomized study.
            (Fabbrocini et al., 2014) Download
BACKGROUND:  Treatment of seborrheic dermatitis (SD) includes various options with different success and safety limitations. OBJECTIVE:  To evaluate the efficacy of topical nicotinamide (NCT) in the treatment of SD. METHODS:  A total of 48 patients with mild to moderate SD of the face were enrolled in the study (36 males and 12 females; age 20-50 years). Patients were randomized into two groups A and B, who were treated once a day with topical administration of NCT 4% cream and with the vehicle without NCT (placebo), respectively. Clinical measures were assessed by erythema, scaling, and infiltration, which were evaluated using a four-point scale 0-3 before starting treatment and after 2, 6, and 12 weeks' therapy. RESULTS:  In comparison with baseline, a reduction of 75% of the total score was observed in patients treated with NCT, whereas for placebo-treated patients the reduction was of 35% (p < 0.05). CONCLUSION:  Topical NCT 4% can have a potential for the treatment of SD.

Effective treatment of mitochondrial myopathy by nicotinamide riboside, a vitamin B3.
            (Khan et al., 2014) Download
Nutrient availability is the major regulator of life and reproduction, and a complex cellular signaling network has evolved to adapt organisms to fasting. These sensor pathways monitor cellular energy metabolism, especially mitochondrial ATP production and NAD(+)/NADH ratio, as major signals for nutritional state. We hypothesized that these signals would be modified by mitochondrial respiratory chain disease, because of inefficient NADH utilization and ATP production. Oral administration of nicotinamide riboside (NR), a vitamin B3 and NAD(+) precursor, was previously shown to boost NAD(+) levels in mice and to induce mitochondrial biogenesis. Here, we treated mitochondrial myopathy mice with NR. This vitamin effectively delayed early- and late-stage disease progression, by robustly inducing mitochondrial biogenesis in skeletal muscle and brown adipose tissue, preventing mitochondrial ultrastructure abnormalities and mtDNA deletion formation. NR further stimulated mitochondrial unfolded protein response, suggesting its protective role in mitochondrial disease. These results indicate that NR and strategies boosting NAD(+) levels are a promising treatment strategy for mitochondrial myopathy.


Pharmacological targeting of IDO-mediated tolerance for treating autoimmune disease
            (Penberthy, 2007) Download
Cells at the maternal-fetal interface express indoleamine 2,3 dioxygenase (IDO) to consume all local tryptophan for the express purpose of starving adjacent maternal T cells of this most limiting and essential amino acid. This stops local T cell proliferation to ultimately result in the most dramatic example of immune tolerance, acceptance of the fetus. By contrast, inhibition of IDO using 1-methyl-tryptophan causes a sudden catastrophic rejection of the mammalian fetus. Immunomodulatory factors including IFNgamma, TNFalpha, IL-1, and LPS use IDO induction in responsive antigen presenting cells (APCs) also to transmit tolerogenic signals to T cells. Thus it makes sense to consider IDO induction towards tolerance for autoimmune diseases in general. Approaches to cell specific therapeutic IDO induction with NAD precursor supplementation to prevent the collateral non-T cell pathogenesis due to chronic TNFalpha-IDO activated tryptophan depletion in autoimmune diseases are reviewed. Tryptophan is an essential amino acid most immediately because it is the only precursor for the endogenous biosynthesis of nicotinamide adenine dinucleotide (NAD). Both autoimmune disease and the NAD deficiency disease pellagra occur in women at greater than twice the frequency of occurrence in men. The importance of IDO dysregulation manifest as autoimmune pellagric dementia is genetically illustrated for Nasu-Hakola Disease (or PLOSL), which is caused by a mutation in the IDO antagonizing genes TYROBP/DAP12 or TREM2. Loss of function leads to psychotic symptoms rapidly progressing to presenile dementia likely due to unchecked increases in microglial IDO expression, which depletes neurons of tryptophan causing neurodegeneration. Administration of NAD precursors rescued entire mental hospitals of dementia patients literally overnight in the 1930's and NAD precursors should help Nasu-Hakola patients as well. NAD depletion mediated by peroxynitrate PARP1 activation is one of the few established mechanisms of necrosis. Chronic elevation of TNFalpha leading to necrotic events by NAD depletion in autoimmune disease likely occurs via combination of persistent IDO activation and iNOS-peroxynitrate activation of PARP1 both of which deplete NAD. Pharmacological doses of NAD precursors repeatedly provide dramatic therapeutic benefit for rheumatoid arthritis, type 1 diabetes, multiple sclerosis, colitis, other autoimmune diseases, and schizophrenia in either the clinic or animal models. Collectively these observations support the idea that autoimmune disease may in part be considered as localized pellagra manifesting symptoms particular to the inflamed target tissues. Thus pharmacological doses of NAD precursors (nicotinic acid/niacin, nicotinamide/niacinamide, or nicotinamide riboside) should be considered as potentially essential to the therapeutic success of any IDO-inducing regimen for treating autoimmune diseases. Distinct among the NAD precursors, nicotinic acid specifically activates the g-protein coupled receptor (GPCR) GPR109a to produce the IDO-inducing tolerogenic prostaglandins PGE(2) and PGD(2). Next, PGD(2) is converted to the anti-inflammatory prostaglandin, 15d-PGJ(2). These prostaglandins exert potent anti-inflammatory activities through endogenous signaling mechanisms involving the GPCRs EP2, EP4, and DP1 along with PPARgamma respectively. Nicotinamide prevents type 1 diabetes and ameliorates multiple sclerosis in animal models, while nothing is known about the therapeutic potential of nicotinamide riboside. Alternatively the direct targeting of the non-redox NAD-dependent proteins using resveratrol to activate SIRT1 or PJ34 in order to inhibit PARP1 and prevent autoimmune pathogenesis are also given consideration.

Nicotinamide riboside is uniquely and orally bioavailable in mice and humans.
            (Trammell et al., 2016b) Download
Nicotinamide riboside (NR) is in wide use as an NAD(+) precursor vitamin. Here we determine the time and dose-dependent effects of NR on blood NAD(+) metabolism in humans. We report that human blood NAD(+) can rise as much as 2.7-fold with a single oral dose of NR in a pilot study of one individual, and that oral NR elevates mouse hepatic NAD(+) with distinct and superior pharmacokinetics to those of nicotinic acid and nicotinamide. We further show that single doses of 100, 300 and 1,000 mg of NR produce dose-dependent increases in the blood NAD(+) metabolome in the first clinical trial of NR pharmacokinetics in humans. We also report that nicotinic acid adenine dinucleotide (NAAD), which was not thought to be en route for the conversion of NR to NAD(+), is formed from NR and discover that the rise in NAAD is a highly sensitive biomarker of effective NAD(+) repletion.

Nicotinamide Riboside Opposes Type 2 Diabetes and Neuropathy in Mice.
            (Trammell et al., 2016a) Download
Male C57BL/6J mice raised on high fat diet (HFD) become prediabetic and develop insulin resistance and sensory neuropathy. The same mice given low doses of streptozotocin are a model of type 2 diabetes (T2D), developing hyperglycemia, severe insulin resistance and diabetic peripheral neuropathy involving sensory and motor neurons. Because of suggestions that increased NAD(+) metabolism might address glycemic control and be neuroprotective, we treated prediabetic and T2D mice with nicotinamide riboside (NR) added to HFD. NR improved glucose tolerance, reduced weight gain, liver damage and the development of hepatic steatosis in prediabetic mice while protecting against sensory neuropathy. In T2D mice, NR greatly reduced non-fasting and fasting blood glucose, weight gain and hepatic steatosis while protecting against diabetic neuropathy. The neuroprotective effect of NR could not be explained by glycemic control alone. Corneal confocal microscopy was the most sensitive measure of neurodegeneration. This assay allowed detection of the protective effect of NR on small nerve structures in living mice. Quantitative metabolomics established that hepatic NADP(+) and NADPH levels were significantly degraded in prediabetes and T2D but were largely protected when mice were supplemented with NR. The data justify testing of NR in human models of obesity, T2D and associated neuropathies.

Syntheses of nicotinamide riboside and derivatives: effective agents for increasing nicotinamide adenine dinucleotide concentrations in mammalian cells.
            (Yang et al., 2007) Download
A new two-step methodology achieves stereoselective synthesis of beta-nicotinamide riboside and a series of related amide, ester, and acid nucleosides. Compounds were prepared through a triacetylated-nicotinate ester nucleoside, via coupling of either ethylnicotinate or phenylnicotinate with 1,2,3,5-tetra-O-acetyl-beta-D-ribofuranose. Nicotinamide riboside, nicotinic acid riboside, O-ethylnicotinate riboside, O-methylnicotinate riboside, and several N-alkyl derivatives increased NAD+ concentrations from 1.2-2.7-fold in several mammalian cell lines. These findings establish bioavailability and potent effects of these nucleosides in stimulating the increase of NAD+ concentrations in mammalian cells.

 


References

Belenky, P, et al. (2007), ‘Nicotinamide riboside promotes Sir2 silencing and extends lifespan via Nrk and Urh1/Pnp1/Meu1 pathways to NAD+.’, Cell, 129 (3), 473-84. PubMed: 17482543
Brown, KD, et al. (2014), ‘Activation of SIRT3 by the NAD⁺ precursor nicotinamide riboside protects from noise-induced hearing loss.’, Cell Metab, 20 (6), 1059-68. PubMed: 25470550
Cantó, C, et al. (2012), ‘The NAD(+) precursor nicotinamide riboside enhances oxidative metabolism and protects against high-fat diet-induced obesity.’, Cell Metab, 15 (6), 838-47. PubMed: 22682224
Fabbrocini, G, M Cantelli, and G Monfrecola (2014), ‘Topical nicotinamide for seborrheic dermatitis: an open randomized study.’, J Dermatolog Treat, 25 (3), 241-45. PubMed: 23763270
Gong, B, et al. (2013), ‘Nicotinamide riboside restores cognition through an upregulation of proliferator-activated receptor-γ coactivator 1α regulated β-secretase 1 degradation and mitochondrial gene expression in Alzheimer’s mouse models.’, Neurobiol Aging, 34 (6), 1581-88. PubMed: 23312803
Khan, NA, et al. (2014), ‘Effective treatment of mitochondrial myopathy by nicotinamide riboside, a vitamin B3.’, EMBO Mol Med, 6 721-31. PubMed: 24711540
Penberthy, W. T. (2007), ‘Pharmacological targeting of IDO-mediated tolerance for treating autoimmune disease’, Curr Drug Metab, 8 (3), 245-66. PubMed: 17430113
Trammell, SA, et al. (2016a), ‘Nicotinamide Riboside Opposes Type 2 Diabetes and Neuropathy in Mice.’, Sci Rep, 6 26933. PubMed: 27230286
Trammell, SA, et al. (2016b), ‘Nicotinamide riboside is uniquely and orally bioavailable in mice and humans.’, Nat Commun, 7 12948. PubMed: 27721479
Yang, T, NY Chan, and AA Sauve (2007), ‘Syntheses of nicotinamide riboside and derivatives: effective agents for increasing nicotinamide adenine dinucleotide concentrations in mammalian cells.’, J Med Chem, 50 (26), 6458-61. PubMed: 18052316