GO:0047280 nicotinamide phosphoribosyltransferase activity: Mechanism, Genes and Research Methods
Research-grade guide for scientists and biopharma professionals
Key Takeaways
• GO:0047280 describes the enzymatic activity that converts nicotinamide and 5-phospho-alpha-D-ribose 1-diphosphate (PRPP) into nicotinamide mononucleotide (NMN), a rate-limiting step in NAD+ salvage.
• The enzyme responsible, NAMPT, is the rate-limiting enzyme in the NAD+ salvage pathway and is essential for maintaining cellular NAD+ levels.
• NAMPT exists both intracellularly (iNAMPT) and extracellularly (eNAMPT); eNAMPT is secreted and can act as a cytokine-like molecule affecting aging and cancer.
• NAD+ produced via this activity regulates diverse processes including circadian rhythms, immune evasion, and senescence-associated secretion.
• Dysregulation of NAMPT is implicated in cancer, metabolic disorders, and aging; both inhibitors and positive allosteric modulators are being developed.
• CRISPR-based models (knockout, point mutation, knock-in, overexpression) are powerful tools to dissect NAMPT function and its role in disease.
Description
Nicotinamide phosphoribosyltransferase (NAMPT) activity, encoded by GO:0047280, catalyzes the condensation of nicotinamide with 5-phospho-alpha-D-ribose 1-diphosphate (PRPP) to form nicotinamide mononucleotide (NMN), a key step in the NAD+ salvage pathway. This activity is essential for maintaining cellular NAD+ pools, which are critical for energy metabolism, DNA repair, and signaling. NAMPT is the rate-limiting enzyme in this pathway, and its expression is tightly regulated in response to metabolic and environmental cues. Beyond its intracellular role, NAMPT can be secreted (eNAMPT) and function as a cytokine-like molecule, influencing systemic aging and tumor progression. Given its central role in NAD+ biology, NAMPT is a focal point for research in cancer, metabolism, and aging, with therapeutic strategies targeting its activity under active investigation.
nicotinamide phosphoribosyltransferase activity At A Glance
| GO ID | GO:0047280 |
|---|---|
| GO term | nicotinamide phosphoribosyltransferase activity |
| Ontology | molecular_function |
| Synonym | nicotinamide mononucleotide pyrophosphorylase activity; nicotinamide mononucleotide synthetase activity; nicotinamide-nucleotide:diphosphate phospho-alpha-D-ribosyltransferase activity; NMN diphosphorylase activity; NMN pyrophosphorylase activity; NMN synthetase activity |
| Major function | Catalyzes the formation of nicotinamide mononucleotide (NMN) from nicotinamide and PRPP, a rate-limiting step in NAD+ salvage. |
| Reaction | diphosphate + nicotinamide mononucleotide = 5-phospho-alpha-D-ribose 1-diphosphate + H+ + nicotinamide |
| Cofactors | None required; uses PRPP as phosphoribosyl donor. |
| Localization | Cytoplasm, nucleus, and secreted extracellularly (eNAMPT). |
| Key enzyme | NAMPT (nicotinamide phosphoribosyltransferase). |
What Is GO:0047280?
GO:0047280 describes the catalytic activity of nicotinamide phosphoribosyltransferase, which mediates the reaction: diphosphate + nicotinamide mononucleotide = 5-phospho-alpha-D-ribose 1-diphosphate + H+ + nicotinamide. In simpler terms, it transfers the phosphoribosyl group from PRPP to nicotinamide, producing NMN and pyrophosphate. This activity is synonymous with NMN pyrophosphorylase, NMN synthetase, and nicotinamide mononucleotide pyrophosphorylase, reflecting its role in NAD+ biosynthesis.
Why Is nicotinamide phosphoribosyltransferase activity Important in Cell Biology?
NAMPT activity is indispensable for NAD+ homeostasis, which is central to cellular energy metabolism, redox balance, and signaling. Through NAD+ production, it influences critical processes such as circadian rhythm regulation, immune responses, and aging. Dysregulated NAMPT activity is observed in numerous cancers, where it supports tumor growth and immune evasion, and in metabolic and neurodegenerative diseases. Consequently, NAMPT is a promising therapeutic target, with both inhibitors and activators being explored.
• Maintains NAD+ levels essential for glycolysis, TCA cycle, and oxidative phosphorylation.
• Regulates circadian gene expression via NAD+-dependent SIRT1 and CLOCK.
• Supports tumor immune evasion by sustaining PD-L1 expression.
• Secreted eNAMPT delays aging and extends lifespan in mice.
• Drives proinflammatory senescence-associated secretome.
• Promotes angiogenesis in triple-negative breast cancer.
• Inhibited by miR-146a, linking AMPK signaling to NAD+ decline.
• Positive allosteric modulators are being developed for therapeutic use.
• Implicated in metabolic disorders such as obesity and diabetes.
• Potential biomarker and target in neurodegenerative diseases.
Molecular Mechanism of nicotinamide phosphoribosyltransferase activity
Substrate Binding and Catalysis
In simple terms: NAMPT grabs nicotinamide and PRPP, then joins them to make NMN.
NAMPT catalyzes the transfer of the phosphoribosyl group from PRPP to nicotinamide, forming NMN and releasing pyrophosphate. The enzyme operates through an ordered bi-bi mechanism, with PRPP binding first, followed by nicotinamide. Structural studies reveal a dimeric active site where each monomer contributes residues to substrate binding.
Rate-Limiting Step in NAD+ Salvage
In simple terms: This is the slowest step in recycling NAD+, so it controls how much NAD+ the cell can make.
NAMPT is the rate-limiting enzyme in the NAD+ salvage pathway, converting nicotinamide to NMN, which is then adenylylated to NAD+ by NMNAT enzymes. Its activity is tightly regulated transcriptionally and post-translationally to match cellular NAD+ demand.
Intracellular vs. Extracellular NAMPT
In simple terms: NAMPT can work inside cells or be secreted to act like a signal molecule outside.
Intracellular NAMPT (iNAMPT) maintains NAD+ pools, while extracellular NAMPT (eNAMPT) is secreted and can function as a cytokine, influencing systemic metabolism and aging. eNAMPT is found in extracellular vesicles and can delay aging in mice.
Regulation by NAD+ Consumers
In simple terms: Enzymes that use NAD+ can affect NAMPT, creating a feedback loop.
NAD+-consuming enzymes such as SIRT1 and PARPs influence NAMPT expression and activity, establishing a feedback loop to maintain NAD+ homeostasis. For example, CLOCK-SIRT1 axis regulates Nampt transcription in a circadian manner.
Pharmacological Modulation
In simple terms: Drugs can turn NAMPT up or down, which is useful for treating diseases.
NAMPT inhibitors (e.g., FK866) deplete NAD+ and are investigated as anticancer agents. Conversely, positive allosteric modulators (N-PAMs) enhance NAMPT activity and show promise for NAD+ restoration.
Key Genes Involved in GO:0047280 nicotinamide phosphoribosyltransferase activity
The following genes and proteins are directly involved in or regulate nicotinamide phosphoribosyltransferase activity and its downstream pathways.
| Gene | Major Role | Research Relevance |
|---|---|---|
| NAMPT | Encodes nicotinamide phosphoribosyltransferase, the enzyme catalyzing the rate-limiting step in NAD+ salvage. | Central to NAD+ biology; target for cancer, metabolic, and aging research. |
| NMNAT1 | Nicotinamide mononucleotide adenylyltransferase 1, converts NMN to NAD+. | Downstream of NAMPT; mutations cause retinal degeneration. |
| NMNAT2 | NMNAT isoform in neurons, maintains axonal NAD+. | Implicated in neurodegeneration. |
| NMNAT3 | Mitochondrial NMNAT, supports mitochondrial NAD+. | Linked to mitochondrial function. |
| SIRT1 | NAD+-dependent deacetylase, regulates circadian rhythm and metabolism. | Feedback regulation of NAMPT; target in aging research. |
| CLOCK | Transcription factor regulating Nampt expression in circadian cycle. | Links circadian clock to NAD+ salvage. |
| PARP1 | NAD+-consuming enzyme in DNA repair. | Influences NAMPT expression via NAD+ depletion. |
| CD38 | NAD+ glycohydrolase, major NAD+ consumer. | Modulates NAMPT activity indirectly. |
| AMPK | Energy sensor kinase, regulates NAMPT via miR-146a. | Links energy stress to NAD+ decline. |
| miR-146a | MicroRNA suppressing NAMPT translation. | Mediates AMPK anti-aging effects. |
| PD-L1 | Immune checkpoint protein, expression maintained by NAD+. | NAMPT inhibition reduces PD-L1 and tumor immune evasion. |
| IL-6 | Cytokine in senescence-associated secretome, regulated by NAD+. | NAMPT affects inflammatory senescence. |
| IL-8 | Another SASP factor modulated by NAD+. | Links NAMPT to inflammation. |
| VEGF | Angiogenic factor induced by eNAMPT in TNBC. | eNAMPT drives pericyte-rich vasculature. |
| SIRT6 | NAD+-dependent deacetylase, regulates senescence. | NAD+ decline affects SASP via SIRT6. |
| FK866 | NAMPT inhibitor (chemical, not gene). | Used to study NAD+ depletion. |
| N-PAMs | Positive allosteric modulators of NAMPT. | Potential therapeutics for NAD+ restoration. |
How Is nicotinamide phosphoribosyltransferase activity Regulated?
NAMPT activity is regulated at multiple levels. Transcriptionally, the Nampt gene is controlled by circadian clock components CLOCK and SIRT1, creating a feedback loop that couples NAD+ levels to the circadian cycle. Post-transcriptionally, miR-146a suppresses NAMPT translation downstream of AMPK activation, linking energy stress to NAD+ decline. At the protein level, NAMPT can be secreted as eNAMPT, and its extracellular levels are influenced by metabolic state and aging. Additionally, NAD+ consumers such as PARP1 and CD38 can deplete NAD+, indirectly upregulating NAMPT expression as a compensatory mechanism. Pharmacological modulation with inhibitors (e.g., FK866) or positive allosteric modulators (N-PAMs) further demonstrates the druggability of this enzyme.
nicotinamide phosphoribosyltransferase activity and Human Disease
| Gene | Disease / Biology | Potential Experimental Model |
|---|---|---|
| NAMPT | Cancer (e.g., breast, leukemia) | NAMPT knockout or overexpression in cancer cell lines; xenograft models. |
| NAMPT | Aging and senescence | NAMPT transgenic or KO mice; eNAMPT supplementation. |
| NAMPT | Metabolic disorders (obesity, diabetes) | Tissue-specific NAMPT KO mice; high-fat diet studies. |
| NAMPT | Inflammation | NAMPT inhibitors in inflammatory disease models. |
| NAMPT | Circadian rhythm disruption | Liver-specific NAMPT KO; circadian behavioral assays. |
NAMPT in Cancer
NAMPT is frequently overexpressed in various cancers, where it supports rapid proliferation by maintaining NAD+ levels. In triple-negative breast cancer, extracellular NAMPT (eNAMPT) drives abnormal pericyte-rich vasculature, promoting tumor growth. NAD+ metabolism also maintains inducible PD-L1 expression, enabling tumor immune evasion; inhibition of NAMPT reduces PD-L1 and enhances antitumor immunity. These findings highlight NAMPT as a promising therapeutic target in oncology.
NAMPT in Aging and Senescence
Declining NAD+ levels are a hallmark of aging, and NAMPT activity is critical for NAD+ salvage. Extracellular vesicle-contained eNAMPT from adipose tissue delays aging and extends lifespan in mice, suggesting a systemic role. NAD+ metabolism also governs the proinflammatory senescence-associated secretome, with NAD+ depletion promoting SASP. Thus, modulating NAMPT activity may mitigate age-related pathologies.
NAMPT in Metabolic and Inflammatory Disorders
NAMPT is implicated in obesity, insulin resistance, and inflammation. The anti-aging effect of AMPK is partly mediated via suppression of NAMPT by miR-146a, linking energy metabolism to NAD+ decline. eNAMPT can act as a proinflammatory cytokine, contributing to metabolic dysfunction. Targeting NAMPT may offer therapeutic benefits in metabolic diseases.
From nicotinamide phosphoribosyltransferase activity-Related Genes to Experimental Models
| Research Question | Suitable Model |
|---|---|
| What is the effect of NAMPT loss on cell viability? | NAMPT knockout cell lines (e.g., CRISPR-Cas9). |
| How does a specific NAMPT mutation affect enzyme activity? | Point mutation knock-in cell lines. |
| Can tagged NAMPT reveal its interactome? | Knock-in of epitope-tagged NAMPT. |
| Does NAMPT overexpression alter NAD+ levels and metabolism? | NAMPT overexpression cell lines or transgenic mice. |
| What is the role of eNAMPT in aging? | eNAMPT overexpression or supplementation in mice. |
| How does NAMPT inhibition affect tumor immune evasion? | NAMPT knockout or inhibitor-treated tumor models. |
How to Study the nicotinamide phosphoribosyltransferase activity Process
| Method | What It Measures | Typical Application |
|---|---|---|
| NAMPT activity assay | Enzymatic conversion of nicotinamide to NMN | Screening inhibitors/activators. |
| NAD+ quantification (HPLC/MS) | Cellular NAD+ levels | Assessing NAMPT impact on NAD+. |
| qRT-PCR | NAMPT mRNA expression | Regulation studies. |
| Western blot | NAMPT protein levels | Expression analysis. |
| ELISA | eNAMPT secretion | Extracellular NAMPT studies. |
| CRISPR knockout | Gene function loss | Phenotypic analysis. |
| CRISPR knock-in | Tagged or mutant NAMPT | Localization/interactome. |
| RNA-seq | Transcriptome changes | Pathway analysis. |
Enzymatic Activity Assays
NAMPT activity can be measured using coupled enzymatic assays that monitor NAD+ production or NMN formation. Radioactive or fluorescent substrates allow sensitive detection. These assays are essential for characterizing inhibitors and activators.
NAD+ Quantification
Cellular NAD+ levels are quantified using enzymatic cycling assays, HPLC, or mass spectrometry. These methods reveal the impact of NAMPT modulation on NAD+ pools.
Gene Expression Analysis
NAMPT mRNA levels are assessed by qRT-PCR, RNA-seq, or Northern blot. Protein levels are analyzed by Western blot, ELISA, or immunohistochemistry. These techniques are used to study regulation by circadian clock or miR-146a.
CRISPR Screening
Genome-wide CRISPR screens can identify genes that modulate NAMPT dependency or NAD+ metabolism. Such screens have uncovered synthetic lethal interactions and resistance mechanisms.
How CRISPR Can Be Used to Study GO:0047280 nicotinamide phosphoribosyltransferase activity
Knockout
CRISPR-Cas9 knockout of NAMPT in cell lines abolishes enzyme activity, leading to NAD+ depletion and cell death, confirming its essential role. Knockout models are used to study NAMPT dependency in cancer and metabolism.
Point Mutation
Introducing point mutations in the NAMPT catalytic domain via CRISPR can dissect residues critical for substrate binding or catalysis. Such models help understand inherited or acquired enzyme deficiencies.
Knock-in
Knock-in of epitope tags (e.g., FLAG, HA) into the endogenous NAMPT locus allows for protein purification and interactome studies. Knock-in of disease-associated mutations can model human pathologies.
Overexpression
CRISPR activation (CRISPRa) or transgenic overexpression of NAMPT increases NAD+ levels and can delay aging or promote tumor growth. Overexpression models are valuable for studying eNAMPT secretion and systemic effects.
How EDITGENE Supports nicotinamide phosphoribosyltransferase activity Research
Researchers studying nicotinamide phosphoribosyltransferase activity-related genes often need to determine whether a candidate gene is causally involved in NAD+ metabolism, aging, or cancer. EDITGENE provides comprehensive CRISPR-based services to create precisely engineered cell and animal models, enabling rigorous functional studies.
Contact EDITGENE today to design your custom CRISPR model for nicotinamide phosphoribosyltransferase activity research.
Frequently Asked Questions About nicotinamide phosphoribosyltransferase activity
What is nicotinamide phosphoribosyltransferase activity?
It is the enzymatic activity (GO:0047280) that converts nicotinamide and PRPP to NMN, a key step in NAD+ salvage.
What genes are involved in nicotinamide phosphoribosyltransferase activity?
The primary gene is NAMPT, which encodes the enzyme; downstream genes include NMNAT1-3, SIRT1, and CLOCK.
What is the role of NAMPT in cancer?
NAMPT is often overexpressed in cancer, supporting NAD+ production for proliferation and immune evasion.
How is NAMPT activity regulated?
It is regulated transcriptionally by circadian clock, post-transcriptionally by miR-146a, and through feedback from NAD+ consumers.
What diseases are associated with NAMPT dysfunction?
Cancer, aging, metabolic disorders, and inflammatory diseases.
Can NAMPT be targeted therapeutically?
Yes, inhibitors like FK866 and positive allosteric modulators are in development.
What is eNAMPT?
Extracellular NAMPT, secreted and acting as a cytokine-like molecule, involved in aging and cancer.
How can I study NAMPT activity in the lab?
Use enzymatic assays, NAD+ quantification, CRISPR knockouts, and overexpression models.
What is the difference between iNAMPT and eNAMPT?
iNAMPT is intracellular and maintains NAD+; eNAMPT is secreted and affects systemic processes.
Are there mouse models for NAMPT research?
Yes, tissue-specific knockouts and transgenic overexpression models exist.
Conclusion
GO:0047280, nicotinamide phosphoribosyltransferase activity, is a fundamental enzymatic function in NAD+ salvage, with far-reaching implications for metabolism, aging, and cancer. The enzyme NAMPT and its extracellular form eNAMPT are key regulators of NAD+ homeostasis and systemic physiology. Continued research using advanced CRISPR models will unravel the precise mechanisms and therapeutic potential of targeting this activity.
References
- 1. Garten A et al.. 2015. Physiological and pathophysiological roles of NAMPT and NAD metabolism.. Nat Rev Endocrinol 11(9):535-46 PMID: 26215259
- 2. Nacarelli T et al.. 2019. NAD(+) metabolism governs the proinflammatory senescence-associated secretome.. Nat Cell Biol 21(3):397-407 PMID: 30778219
- 3. Yoshida M et al.. 2019. Extracellular Vesicle-Contained eNAMPT Delays Aging and Extends Lifespan in Mice.. Cell Metab 30(2):329-342.e5 PMID: 31204283
- 4. Lv H et al.. 2021. NAD(+) Metabolism Maintains Inducible PD-L1 Expression to Drive Tumor Immune Evasion.. Cell Metab 33(1):110-127.e5 PMID: 33171124
- 5. Nakahata Y et al.. 2009. Circadian control of the NAD+ salvage pathway by CLOCK-SIRT1.. Science 324(5927):654-7 PMID: 19286518
- 6. Moro M et al.. 2024. Extracellular nicotinamide phosphoribosyltransferase (eNAMPT) drives abnormal pericyte-rich vasculature in triple-negative breast cancer.. Angiogenesis 28(1):4 PMID: 39636369
- 7. Gong H et al.. 2022. miR-146a impedes the anti-aging effect of AMPK via NAMPT suppression and NAD(+)/SIRT inactivation.. Signal Transduct Target Ther 7(1):66 PMID: 35241643
- 8. Shen Z et al.. 2023. Synthesis, Optimization, and Structure-Activity Relationships of Nicotinamide Phosphoribosyltransferase (NAMPT) Positive Allosteric Modulators (N-PAMs).. J Med Chem 66(24):16704-16727 PMID: 38096366
