GO:0019674 NAD+ metabolic process: Pathway, Genes, Functions and Research Methods
Research-grade guide for scientists and biopharma professionals
Key Takeaways
• GO:0019674 (NAD+ metabolic process) describes all biochemical reactions that synthesize, consume, recycle, and interconvert nicotinamide adenine dinucleotide (NAD+) and its reduced form NADH.
• NAD+ is a central redox coenzyme and a substrate for signaling enzymes such as sirtuins, PARPs, and CD38, linking metabolism to gene regulation, DNA repair, and immune responses.
• Cellular NAD+ levels decline with age and in multiple diseases, making the pathway a major target for anti-aging and therapeutic interventions.
• Key enzymes include NAMPT, NMNAT1-3, NADK, CD38, PARP1, and SIRT1-7, which together maintain NAD+ homeostasis.
• Dysregulated NAD+ metabolism is implicated in cancer, neurodegeneration, metabolic disorders, and inflammatory conditions.
• CRISPR-based knockout, knock-in, point mutation, and overexpression models are essential to dissect causal roles of NAD+ pathway genes in health and disease.
Description
NAD+ metabolic process (GO:0019674) encompasses the chemical reactions and pathways involving nicotinamide adenine dinucleotide (NAD+), a coenzyme that interconverts with its reduced form NADH in many redox and catabolic reactions. This process is fundamental to cellular energy metabolism, as NAD+ serves as an electron carrier in glycolysis, the tricarboxylic acid cycle, and oxidative phosphorylation, while also acting as a substrate for signaling enzymes that regulate DNA repair, stress responses, and gene expression. The dual role of NAD+ as both a redox cofactor and a signaling molecule places it at the intersection of metabolism, aging, and disease. Research into NAD+ metabolism has accelerated due to its implications in age-related decline, cancer, neurodegeneration, and metabolic disorders. The pathway includes de novo synthesis from tryptophan, the salvage pathway from nicotinamide, and the Preiss-Handler pathway from nicotinic acid, all converging on NAD+ production. Understanding these routes and their regulation is critical for developing therapeutic strategies that modulate NAD+ levels, such as nicotinamide mononucleotide (NMN) supplementation, which has shown safety and anti-aging effects in human clinical trials. This article provides a research-grade overview of GO:0019674, covering its definition, molecular mechanisms, key genes, disease associations, and experimental models. It is designed for researchers seeking to study NAD+ metabolism using CRISPR-based tools and other advanced methodologies.
NAD+ metabolic process At A Glance
| GO ID | GO:0019674 |
|---|---|
| GO term | NAD+ metabolic process |
| Ontology | biological_process |
| Synonym | NAD metabolic process; NAD metabolism; NAD (oxidized) metabolic process; nicotinamide adenine dinucleotide metabolic process; oxidized NAD metabolic process |
| Major function | Synthesis, recycling, and interconversion of NAD+ and NADH; supports redox reactions and signaling |
| Key enzymes | NAMPT, NMNAT1-3, NADK, CD38, PARP1, SIRT1-7 |
| Subcellular locations | Cytoplasm, nucleus, mitochondria, extracellular space |
| Related pathways | Salvage pathway, Preiss-Handler pathway, de novo synthesis from tryptophan, NAD+ phosphorylation |
What Is GO:0019674?
GO:0019674 (NAD+ metabolic process) is defined by the Gene Ontology as the chemical reactions and pathways involving nicotinamide adenine dinucleotide (NAD+), a coenzyme that interconverts with its reduced form, NADH, in many redox and catabolic reactions. In simpler terms, it covers all the ways cells make, break down, recycle, and use NAD+ and NADH to carry electrons and control signaling. This includes biosynthesis from precursors like tryptophan, nicotinamide, and nicotinic acid, as well as consumption by enzymes such as sirtuins, PARPs, and CD38.
Why Is NAD+ metabolic process Important in Cell Biology?
NAD+ metabolic process is essential for life because NAD+ is required for fundamental redox reactions in glycolysis, the TCA cycle, and oxidative phosphorylation, and it serves as a substrate for enzymes that regulate DNA repair, chromatin remodeling, and immune responses. Its decline is a hallmark of aging and contributes to metabolic dysfunction, neurodegeneration, and cancer progression. Consequently, modulating NAD+ levels through genetic or pharmacological means holds therapeutic potential for a wide range of diseases.
• Maintains cellular energy production by shuttling electrons in redox reactions.
• Regulates sirtuin activity, influencing aging, inflammation, and metabolism.
• Supports DNA repair through PARP enzymes, which consume NAD+.
• Modulates immune cell function and stemness.
• Declines with age, contributing to age-related diseases.
• Implicated in cancer metabolism and tumor progression.
• Plays a role in neurodegenerative diseases such as Alzheimer's and Parkinson's.
• Targeted by NAD+ precursors (NMN, NR) in clinical trials for anti-aging.
• Involved in inflammatory signaling via CD38 and copper-dependent pathways.
• Offers druggable nodes for metabolic and inflammatory disorders.
What Happens During NAD+ metabolic process?
De Novo Synthesis from Tryptophan
In simple terms: The body can build NAD+ from scratch using the amino acid tryptophan.
The de novo pathway converts tryptophan through a series of enzymatic steps to nicotinic acid mononucleotide (NaMN), which is then converted to NAD+ via the Preiss-Handler pathway. This route is quantitatively minor in mammals but essential in certain tissues.
Salvage Pathway from Nicotinamide
In simple terms: Most NAD+ is recycled from nicotinamide, a breakdown product of NAD+.
The salvage pathway is the primary source of NAD+ in mammalian cells. NAMPT (nicotinamide phosphoribosyltransferase) converts nicotinamide to nicotinamide mononucleotide (NMN), which is then adenylylated by NMNAT1-3 to form NAD+. This cycle is critical for maintaining NAD+ levels and is regulated by circadian rhythms and metabolic status.
Preiss-Handler Pathway from Nicotinic Acid
In simple terms: NAD+ can also be made from nicotinic acid (vitamin B3).
Nicotinic acid is converted to NaMN by NAPRT, then to NAAD, and finally to NAD+ by NMNAT and NAD synthase. This pathway is important in tissues that rely on dietary niacin.
NAD+ Phosphorylation and Dephosphorylation
In simple terms: NAD+ can be phosphorylated to NADP+ and back.
NAD kinase (NADK) phosphorylates NAD+ to NADP+, which is used in reductive biosynthesis and antioxidant defense. Dephosphorylation by phosphatases regenerates NAD+. This interconversion is a key regulatory node.
Consumption by Signaling Enzymes
In simple terms: NAD+ is consumed by enzymes that use it to modify proteins.
Sirtuins, PARPs, and CD38 consume NAD+ as a substrate, producing nicotinamide and ADP-ribose or O-acetyl-ADP-ribose. This consumption is a major determinant of cellular NAD+ levels and links metabolism to gene regulation, DNA repair, and calcium signaling.
Key Genes Involved in GO:0019674 NAD+ metabolic process
The following genes encode key enzymes and regulators of NAD+ metabolic process, representing major nodes for experimental interrogation.
| Gene | Major Role | Research Relevance |
|---|---|---|
| NAMPT | Rate-limiting enzyme in salvage pathway; converts nicotinamide to NMN | Target for NAD+ boosting; implicated in cancer and inflammation |
| NMNAT1 | Nuclear NMNAT; synthesizes NAD+ from NMN | Mutations cause retinal degeneration; key for nuclear NAD+ |
| NMNAT2 | Cytoplasmic NMNAT; essential for axon survival | Linked to neurodegeneration; knockout lethal |
| NMNAT3 | Mitochondrial NMNAT; produces NAD+ in mitochondria | Regulates mitochondrial metabolism; potential target for metabolic diseases |
| NADK | Phosphorylates NAD+ to NADP+ | Maintains NADP+ pools for antioxidant defense; knockout affects redox balance |
| CD38 | NAD+ glycohydrolase; consumes NAD+ to produce ADPR and cADPR | Declines with age; inhibition boosts NAD+ and improves metabolic health |
| PARP1 | DNA repair enzyme; consumes NAD+ for poly-ADP-ribosylation | Hyperactivation in DNA damage depletes NAD+; target in cancer and neurodegeneration |
| SIRT1 | NAD+-dependent deacetylase; regulates metabolism and aging | Key mediator of caloric restriction; target for anti-aging interventions |
| SIRT3 | Mitochondrial deacetylase; regulates ROS and metabolism | Protects against age-related metabolic decline |
| SIRT6 | Nuclear deacetylase; involved in DNA repair and longevity | Modulates inflammation and cancer; potential therapeutic target |
| NADSYN1 | NAD synthetase; final step of Preiss-Handler and de novo pathways | Mutations cause NAD deficiency syndromes; essential for development |
| QPRT | Quinolinate phosphoribosyltransferase; de novo pathway | Regulates tryptophan-derived NAD+ synthesis; linked to neuroprotection |
| NAPRT | Nicotinic acid phosphoribosyltransferase; Preiss-Handler pathway | Determines nicotinic acid utilization; potential cancer target |
| NMRK1 | Nicotinamide riboside kinase 1; phosphorylates NR to NMN | Mediates effects of NR supplementation; regulates NAD+ salvage |
| NMRK2 | Nicotinamide riboside kinase 2; muscle-specific NR kinase | Important for muscle NAD+ homeostasis; target for exercise mimetics |
| ACMSD | Aminocarboxymuconate semialdehyde decarboxylase; regulates de novo pathway | Modulates NAD+ synthesis from tryptophan; linked to kidney and liver diseases |
| SLC25A51 | Mitochondrial NAD+ transporter | Essential for mitochondrial NAD+ import; knockout impairs respiration |
| CD73 | Extracellular NAD+ ectoenzyme; produces adenosine | Regulates extracellular NAD+ and immune suppression |
How Is NAD+ metabolic process Regulated?
NAD+ metabolism is regulated at multiple levels. The salvage pathway enzyme NAMPT is controlled by circadian clock components, metabolic sensors such as AMPK, and inflammatory signals. Sirtuins and PARPs consume NAD+, creating a feedback loop that adjusts biosynthesis to demand. CD38 expression increases with age and inflammation, reducing NAD+ availability. Additionally, NAD+ levels are influenced by dietary precursors (NMN, NR, nicotinamide, nicotinic acid) and by hormonal signals like insulin and glucagon. This complex regulation ensures that NAD+ homeostasis is tightly coupled to cellular energy status and stress responses.
NAD+ metabolic process and Human Disease
| Gene | Disease / Biology | Potential Experimental Model |
|---|---|---|
| NAMPT | Cancer, inflammation, metabolic syndrome | Conditional knockout in liver or adipose tissue; overexpression in cancer cell lines |
| CD38 | Aging, inflammation, immune suppression | CD38 knockout mice; point mutation of catalytic domain |
| SIRT1 | Aging, neurodegeneration, metabolic disorders | SIRT1 knockout and knock-in deacetylase-dead mutants |
| PARP1 | Cancer, neurodegeneration, DNA repair defects | PARP1 knockout; point mutation of catalytic activity |
| NMNAT1 | Retinal degeneration, neuropathy | NMNAT1 knockout and point mutation knock-in mice |
NAD+ Metabolism in Aging and Neurodegeneration
NAD+ levels decline with age in multiple tissues, contributing to mitochondrial dysfunction, DNA damage, and neuroinflammation. In Alzheimer's and Parkinson's diseases, reduced NAD+ availability impairs sirtuin and PARP functions, exacerbating neuronal loss. Boosting NAD+ via precursors has shown neuroprotective effects in preclinical models and is being tested clinically.
NAD+ Metabolism in Cancer
Cancer cells often upregulate NAD+ biosynthesis to support rapid proliferation and DNA repair. NAMPT inhibitors deplete NAD+ and selectively kill cancer cells with high NAD+ demand, though toxicity limits their use. Conversely, CD38 expression in the tumor microenvironment can suppress anti-tumor immunity by consuming NAD+.
NAD+ Metabolism in Metabolic and Inflammatory Disorders
Obesity and type 2 diabetes are associated with reduced NAD+ levels and impaired sirtuin activity. Inflammatory conditions, such as those driven by copper-signaling pathways, involve CD38-mediated NAD+ depletion. Restoring NAD+ through genetic or pharmacological means improves insulin sensitivity and reduces inflammation in animal models.
From NAD+ metabolic process-Related Genes to Experimental Models
| Research Question | Suitable Model |
|---|---|
| Does loss of NAMPT reduce cellular NAD+ and affect viability? | NAMPT knockout cell lines (CRISPR) |
| Does a specific point mutation in CD38 alter its NAD+ hydrolase activity? | CD38 point-mutation knock-in cells |
| Can overexpression of NMNAT3 rescue mitochondrial NAD+ depletion? | NMNAT3 overexpression cell lines |
| What is the effect of SIRT1 deacetylase-dead mutation on metabolism? | SIRT1 point-mutation knock-in mice |
| Does tagging endogenous NAMPT with GFP affect its localization? | NAMPT knock-in with fluorescent tag |
| Which genes are essential for NAD+ homeostasis in cancer cells? | Genome-wide CRISPR knockout library screening |
How to Study the NAD+ metabolic process Process
| Method | What It Measures | Typical Application |
|---|---|---|
| Enzymatic cycling assay | Total NAD+ and NADH | Quantifying NAD+ in tissues and cells |
| HPLC/MS | NAD+ and related metabolites | Metabolomic profiling of NAD+ pathway |
| CRISPR knockout screen | Gene essentiality in NAD+ metabolism | Identifying novel regulators |
| RNA-seq | Transcriptional changes upon NAD+ modulation | Pathway analysis |
| Proteomics | Protein expression and modifications | Sirtuin/PARP activity |
| Fluorescent sensors | Real-time NAD+/NADH dynamics | Live-cell imaging |
| Immunoblotting | Protein levels of NAD+ enzymes | Validation of knockout/overexpression |
| Seahorse assay | Mitochondrial respiration | Functional impact of NAD+ changes |
Measuring NAD+ and NADH Levels
NAD+ and NADH can be quantified using enzymatic cycling assays, HPLC, or mass spectrometry. These methods measure total NAD+ and the NAD+/NADH ratio, which reflects cellular redox state.
Genetic Screens for NAD+ Pathway Genes
CRISPR knockout and activation screens can identify genes that regulate NAD+ levels or that are essential in cells with altered NAD+ metabolism. Such screens have revealed dependencies on NAMPT and NMNATs in cancer cells.
Proteomics and Metabolomics
Proteomic analysis of NAD+-dependent enzymes (sirtuins, PARPs) and metabolomic profiling of NAD+ precursors provide a systems-level view of pathway activity.
Imaging NAD+ Dynamics
Genetically encoded fluorescent sensors (e.g., Peredox, SoNar) allow real-time monitoring of NAD+/NADH in live cells, revealing subcellular compartmentalization.
How CRISPR Can Be Used to Study GO:0019674 NAD+ metabolic process
Knockout
CRISPR knockout of NAD+ pathway genes (e.g., NAMPT, NMNAT1, CD38) enables loss-of-function studies to determine their role in NAD+ homeostasis and cellular phenotypes. Knockout cell lines are valuable for drug target validation.
Point Mutation
Introducing specific point mutations (e.g., in the catalytic domain of CD38 or SIRT1) allows precise dissection of enzymatic activity versus scaffolding functions. This is critical for understanding structure-function relationships.
Knock-in
Knock-in of reporter tags (e.g., GFP, luciferase) or disease-associated mutations (e.g., NMNAT1 mutations) creates models to track protein localization, stability, and function in real time.
Overexpression
Overexpression of NAD+ biosynthetic enzymes (e.g., NAMPT, NMNAT3) or NAD+ consumers (e.g., CD38) via CRISPR activation or cDNA delivery can boost or deplete NAD+ levels, mimicking disease states or therapeutic interventions.
How EDITGENE Supports NAD+ metabolic process Research
Researchers studying NAD+ metabolic process-related genes often need to determine whether a candidate gene is causally involved in NAD+ regulation, disease progression, or therapeutic response. CRISPR-based models provide the gold standard for such functional validation, enabling precise genetic perturbations in relevant cell types.
Contact EDITGENE today to design your custom CRISPR model for NAD+ metabolic process research.
Related Products
| Product name | Cat.No. | Species | Gene ID | |
|---|---|---|---|---|
| PC Knockout HEK293 Cell Line | EDJ-KQ216 | Human | 5091 | Details Get a Quote |
| LDHB Knockout HEK293 Cell Line | EDJ-KQ1519 | Human | 3945 | Details Get a Quote |
| GPD1L Knockout HEK293 Cell Line | EDJ-KQ3743 | Human | 23171 | Details Get a Quote |
| MDH1 Knockout HEK293 Cell Line | EDJ-KQ4417 | Human | 4190 | Details Get a Quote |
| ME1 Knockout HEK293 Cell Line | EDJ-KQ5192 | Human | 4199 | Details Get a Quote |
| KMO Knockout HEK293 Cell Line | EDJ-KQ6289 | Human | 8564 | Details Get a Quote |
| MDH1B Knockout HEK293 Cell Line | EDJ-KQ9250 | Human | 130752 | Details Get a Quote |
| NADK2 Knockout HEK293 Cell Line | EDJ-KQ9321 | Human | 133686 | Details Get a Quote |
| NADK Knockout HEK293 Cell Line | EDJ-KQ14363 | Human | 65220 | Details Get a Quote |
| LDHB Knockout A-549 Cell Line | EDJ-KQ21156 | Human | 3945 | Details Get a Quote |
| LDHB Knockout HCT 116 Cell Line | EDJ-KQ21157 | Human | 3945 | Details Get a Quote |
| LDHB Knockout HeLa Cell Line | EDC10188 | Human | 3945 | Details Get a Quote |
| MDH1 Knockout A-549 Cell Line | EDJ-KQ28178 | Human | 4190 | Details Get a Quote |
| MDH1 Knockout HCT 116 Cell Line | EDJ-KQ28180 | Human | 4190 | Details Get a Quote |
| MDH1 Knockout HeLa Cell Line | EDJ-KQ28181 | Human | 4190 | Details Get a Quote |
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Frequently Asked Questions About NAD+ metabolic process
What is NAD+ metabolic process?
NAD+ metabolic process (GO:0019674) encompasses all biochemical reactions that synthesize, recycle, and interconvert nicotinamide adenine dinucleotide (NAD+) and its reduced form NADH, as well as its consumption by signaling enzymes.
What genes are involved in NAD+ metabolic process?
Key genes include NAMPT, NMNAT1-3, NADK, CD38, PARP1, SIRT1-7, NADSYN1, QPRT, NAPRT, NMRK1/2, and SLC25A51.
Why is NAD+ important for aging?
NAD+ levels decline with age, leading to reduced sirtuin and PARP activity, mitochondrial dysfunction, and increased inflammation, which contribute to age-related diseases.
How is NAD+ synthesized in cells?
NAD+ is synthesized via the salvage pathway from nicotinamide, the Preiss-Handler pathway from nicotinic acid, and de novo from tryptophan, with the salvage pathway being the primary source in mammals.
What is the role of CD38 in NAD+ metabolism?
CD38 is an NAD+ glycohydrolase that consumes NAD+ to produce signaling molecules like ADP-ribose and cyclic ADP-ribose, and its expression increases with age and inflammation, reducing NAD+ availability.
Can NAD+ levels be increased by supplements?
Yes, NAD+ precursors such as nicotinamide mononucleotide (NMN) and nicotinamide riboside (NR) have been shown to safely raise NAD+ levels in human clinical trials and may have anti-aging effects.
What diseases are linked to NAD+ metabolic process?
Dysregulated NAD+ metabolism is implicated in cancer, neurodegeneration (Alzheimer's, Parkinson's), metabolic disorders (obesity, diabetes), and inflammatory conditions.
How do sirtuins use NAD+?
Sirtuins are NAD+-dependent deacetylases that remove acetyl groups from proteins, consuming NAD+ and producing nicotinamide and O-acetyl-ADP-ribose, thereby linking metabolism to gene regulation.
What CRISPR models are used to study NAD+ metabolism?
Knockout, point mutation, knock-in, and overexpression models of NAD+ pathway genes are generated using CRISPR-Cas9 to dissect gene function and disease mechanisms.
What is the NAD+/NADH ratio?
The NAD+/NADH ratio reflects the cellular redox state and is critical for maintaining metabolic balance; it is often measured to assess mitochondrial function.
Conclusion
NAD+ metabolic process (GO:0019674) is a fundamental biological pathway that controls energy metabolism, signaling, and stress responses. Its dysregulation is central to aging and many diseases, making it a prime target for therapeutic intervention. CRISPR-based models and advanced screening technologies are indispensable for uncovering the precise roles of NAD+ pathway genes and for developing novel treatments.
References
- 1. Covarrubias AJ et al.. 2021. NAD(+) metabolism and its roles in cellular processes during ageing.. Nat Rev Mol Cell Biol 22(2):119-141 PMID: 33353981
- 2. Amjad S et al.. 2021. Role of NAD(+) in regulating cellular and metabolic signaling pathways.. Mol Metab 49:101195 PMID: 33609766
- 3. Song Q et al.. 2023. The Safety and Antiaging Effects of Nicotinamide Mononucleotide in Human Clinical Trials: an Update.. Adv Nutr 14(6):1416-1435 PMID: 37619764
- 4. Verdin E. 2015. NAD⁺ in aging, metabolism, and neurodegeneration.. Science 350(6265):1208-13 PMID: 26785480
- 5. Navas LE et al.. 2021. NAD(+) metabolism, stemness, the immune response, and cancer.. Signal Transduct Target Ther 6(1):2 PMID: 33384409
- 6. Solier S et al.. 2023. A druggable copper-signalling pathway that drives inflammation.. Nature 617(7960):386-394 PMID: 37100912
- 7. Katsyuba E et al.. 2020. NAD(+) homeostasis in health and disease.. Nat Metab 2(1):9-31 PMID: 32694684
- 8. Migaud ME et al.. 2024. Regulation of and challenges in targeting NAD(+) metabolism.. Nat Rev Mol Cell Biol 25(10):822-840 PMID: 39026037
