GO:0009435 NAD+ biosynthetic process: Metabolic Pathway, Genes, Functions and Research Methods
Research-grade guide for scientists and biopharma professionals
Key Takeaways
• GO:0009435 (NAD+ biosynthetic process) describes the chemical reactions and pathways that build nicotinamide adenine dinucleotide (NAD+), a central redox coenzyme and signaling molecule.
• NAD+ is synthesized from multiple sources including vitamin B3 (niacin, nicotinamide, nicotinamide riboside) through de novo, Preiss-Handler, and salvage routes.
• NAD+ levels decline with age and in metabolic, neurodegenerative, and inflammatory diseases, making this pathway a major therapeutic target.
• Key enzymes include NAMPT, NMNAT1-3, NADSYN1, QPRT, and NAXD/NAXE, which together maintain cellular NAD+ homeostasis.
• CRISPR knockout, point-mutation, knock-in, and overexpression models are essential to dissect causal roles of NAD+ biosynthetic genes in disease.
• Understanding NAD+ biosynthesis informs interventions such as nicotinamide riboside and NMN supplementation, and drug development targeting NAD+ metabolism.
Description
NAD+ (nicotinamide adenine dinucleotide) is an essential redox coenzyme that interconverts with its reduced form NADH in numerous catabolic and redox reactions, and it also serves as a substrate for signaling enzymes such as sirtuins, PARPs, and CD38. The Gene Ontology term GO:0009435, NAD+ biosynthetic process, captures the chemical reactions and pathways that result in the formation of NAD+ from various sources, including vitamin B3. This process is fundamental to cellular energy metabolism, DNA repair, and stress responses, and its dysregulation is implicated in aging, metabolic disorders, neurodegeneration, and cancer. Researchers study NAD+ biosynthesis to understand how cells maintain NAD+ homeostasis and to identify therapeutic opportunities for boosting NAD+ levels in disease. The pathway is compartmentalized and tightly regulated, with distinct enzymes operating in the nucleus, cytoplasm, and mitochondria. Because NAD+ cannot cross cell membranes efficiently, cells rely on local synthesis and salvage to sustain NAD+ pools. This article provides a research-grade overview of GO:0009435, covering its definition, biological stages, key genes, regulation, disease links, and experimental methods including CRISPR-based models. All statements are grounded in the verified literature listed at the end.
NAD+ biosynthetic process At A Glance
| GO ID | GO:0009435 |
|---|---|
| GO term | NAD+ biosynthetic process |
| Ontology | biological_process |
| Synonym | NAD biosynthesis; NAD formation; nicotinamide adenine dinucleotide biosynthesis; NADH biosynthesis; oxidized NAD biosynthesis; reduced NAD biosynthesis |
| Major function | Synthesis of NAD+ from vitamin B3 precursors and other sources, maintaining cellular NAD+ pools for redox reactions and signaling |
| Key enzymes | NAMPT, NMNAT1-3, NADSYN1, QPRT, NAXD, NAXE, and others |
| Subcellular locations | Nucleus, cytoplasm, mitochondria (compartmentalized synthesis) |
| Related pathways | Salvage pathway, Preiss-Handler pathway, de novo synthesis from tryptophan |
| Disease relevance | Aging, metabolic disorders, neurodegeneration, cancer, and inflammatory conditions |
What Is GO:0009435?
GO:0009435 (NAD+ biosynthetic process) is defined by QuickGO as the chemical reactions and pathways resulting in the formation of nicotinamide adenine dinucleotide (NAD+), a coenzyme that interconverts with its reduced form, NADH, in many redox and catabolic reactions. NAD+ is derived from various sources including vitamin B3. In practice, this term encompasses de novo synthesis from tryptophan, the Preiss-Handler pathway from nicotinic acid, and the salvage pathway from nicotinamide and nicotinamide riboside, all converging on the production of NAD+.
Why Is NAD+ biosynthetic process Important in Cell Biology?
NAD+ biosynthesis is critical because NAD+ is required for hundreds of redox reactions and serves as a substrate for enzymes that regulate metabolism, DNA repair, and cell survival. Declining NAD+ levels are a hallmark of aging and contribute to metabolic dysfunction, neurodegeneration, and increased susceptibility to disease. Understanding how cells synthesize and maintain NAD+ is therefore essential for developing interventions that target NAD+ metabolism.
• Maintains cellular redox balance by supplying NAD+ for glycolysis, oxidative phosphorylation, and other metabolic pathways.
• Supports sirtuin and PARP activities, which regulate gene expression, DNA repair, and stress responses.
• NAD+ decline is linked to aging and age-related diseases, making biosynthesis a target for geroprotective strategies.
• Dysregulated NAD+ metabolism is observed in cancer, where it supports tumor growth and survival.
• Neurodegenerative conditions such as Alzheimer's and Parkinson's diseases show altered NAD+ homeostasis.
• Inflammatory and immune responses depend on NAD+ for cytokine production and immune cell function.
• NAD+ biosynthesis enzymes are potential drug targets for metabolic disorders like obesity and diabetes.
• Precise gene editing of NAD+ biosynthetic genes enables causal studies of disease mechanisms.
What Happens During NAD+ biosynthetic 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 quinolinic acid, which is then transformed into nicotinic acid mononucleotide (NaMN) by QPRT. This route is particularly important in the liver and kidney and is regulated by nutritional status.
Preiss-Handler pathway from nicotinic acid
In simple terms: Cells can also make NAD+ from nicotinic acid, a form of vitamin B3.
In the Preiss-Handler pathway, nicotinic acid is converted to NaMN by NAPRT, then to nicotinic acid adenine dinucleotide (NaAD) by NMNAT enzymes, and finally to NAD+ by NADSYN1. This pathway is conserved and contributes to NAD+ pools in various tissues.
Salvage pathway from nicotinamide and nicotinamide riboside
In simple terms: Most cells recycle nicotinamide back into NAD+ through a salvage loop.
The salvage pathway is the primary source of NAD+ in mammalian cells. NAMPT converts nicotinamide to nicotinamide mononucleotide (NMN), which is then adenylylated by NMNAT1-3 to form NAD+. Nicotinamide riboside can also enter this pathway via NRK enzymes. This cycle is essential for maintaining NAD+ levels under fluctuating metabolic demands.
Compartmentalization of NAD+ synthesis
In simple terms: NAD+ is made in different parts of the cell, each with its own enzymes.
NAD+ synthesis is compartmentalized: NMNAT1 is nuclear, NMNAT2 is cytoplasmic and Golgi-associated, and NMNAT3 is mitochondrial. This allows local NAD+ production to support compartment-specific processes such as nuclear DNA repair and mitochondrial metabolism.
Regulation of NAD+ biosynthetic flux
In simple terms: The pathway is turned up or down based on cellular needs and stress.
NAMPT is the rate-limiting enzyme in the salvage pathway and is regulated by circadian rhythms, metabolic status, and inflammatory signals. NAD+ levels are also influenced by consumption by sirtuins, PARPs, and CD38, creating a dynamic balance between synthesis and degradation.
Key Genes Involved in GO:0009435 NAD+ biosynthetic process
The following genes encode enzymes and regulators directly involved in NAD+ biosynthesis (GO:0009435) and are commonly studied in metabolic, aging, and cancer research.
| Gene | Major Role | Research Relevance |
|---|---|---|
| NAMPT | Rate-limiting enzyme converting nicotinamide to NMN in the salvage pathway | Target for boosting NAD+ in aging and metabolic disease |
| NMNAT1 | Nuclear NMNAT catalyzing NMN to NAD+ | Mutations cause retinal degeneration; studied in DNA repair |
| NMNAT2 | Cytoplasmic/Golgi NMNAT essential for neuronal survival | Linked to axon degeneration and neurodegeneration |
| NMNAT3 | Mitochondrial NMNAT producing NAD+ for oxidative metabolism | Studied in mitochondrial function and cancer metabolism |
| NADSYN1 | Glutamine-dependent NAD+ synthetase in Preiss-Handler pathway | Mutations cause NAD+ deficiency disorders |
| QPRT | Converts quinolinic acid to NaMN in de novo pathway | Involved in tryptophan metabolism and neurotoxicity |
| NAPRT | Converts nicotinic acid to NaMN | Determines nicotinic acid utilization |
| NRK1 | Phosphorylates nicotinamide riboside to NMN | Mediates effects of NR supplementation |
| NRK2 | Alternative NR kinase | Tissue-specific NAD+ synthesis |
| NAXD | Repairs damaged NAD+ metabolites | Mutations cause severe neurodevelopmental disorder |
| NAXE | Epimerase involved in NAD+ repair | Defects lead to encephalopathy |
| CD38 | NAD+ glycohydrolase consuming NAD+ | Regulates NAD+ levels in aging and inflammation |
| PARP1 | NAD+-consuming enzyme in DNA repair | Competes with biosynthesis for NAD+ |
| SIRT1 | NAD+-dependent deacetylase | Links NAD+ levels to gene regulation and aging |
| SIRT3 | Mitochondrial NAD+-dependent deacetylase | Regulates mitochondrial metabolism |
| ACMSD | Regulates de novo NAD+ synthesis from tryptophan | Modulates NAD+ levels in liver and kidney |
| IDO1 | Initiates tryptophan catabolism toward NAD+ | Immune regulation and cancer |
| TDO2 | Liver-specific tryptophan dioxygenase | De novo NAD+ synthesis in liver |
How Is NAD+ biosynthetic process Regulated?
NAD+ biosynthesis is regulated at multiple levels. NAMPT expression is controlled by circadian clock components, metabolic sensors such as AMPK, and inflammatory cytokines. The activity of NAD+-consuming enzymes (sirtuins, PARPs, CD38) creates feedback that influences biosynthetic flux. Additionally, substrate availability (vitamin B3 precursors) and hormonal signals modulate pathway activity. Compartmentalization further allows local regulation of NAD+ production in response to specific stressors.
NAD+ biosynthetic process and Human Disease
| Gene | Disease / Biology | Potential Experimental Model |
|---|---|---|
| NAMPT | Metabolic syndrome, aging, cancer | Knockout and overexpression in cell lines and mouse models |
| NMNAT1 | Retinal degeneration, DNA repair defects | Point-mutation knock-in in retinal cells |
| NMNAT2 | Axon degeneration, neurodegeneration | Conditional knockout in neurons |
| NADSYN1 | NAD+ deficiency disorder, congenital malformations | Patient-derived iPSCs with knock-in correction |
| NAXD | Neurodevelopmental disorder with encephalopathy | Knockout and point-mutation models |
Aging and metabolic disorders
NAD+ levels decline with age in multiple tissues, contributing to mitochondrial dysfunction, insulin resistance, and metabolic syndrome. Boosting NAD+ biosynthesis through precursors like nicotinamide riboside or NMN has shown benefits in preclinical models of obesity and diabetes. Genetic models targeting NAMPT and NMNATs help establish causality.
Neurodegeneration
Neurons are particularly sensitive to NAD+ depletion due to high metabolic demand and dependence on NMNAT2 for axon survival. Reduced NAD+ biosynthesis is implicated in Alzheimer's disease, Parkinson's disease, and peripheral neuropathies. Enhancing NAD+ synthesis is being explored as a neuroprotective strategy.
Cancer
Many tumors upregulate NAD+ biosynthetic enzymes such as NAMPT to support rapid proliferation and DNA repair. Targeting NAD+ biosynthesis is a potential therapeutic approach, though normal tissue toxicity must be considered. CRISPR screens have identified NAD+ pathway dependencies in cancer cells.
Inflammatory and immune disorders
NAD+ metabolism influences immune cell function and inflammation. CD38 activation during inflammation consumes NAD+, and reduced NAD+ availability impairs immune responses. Modulating NAD+ biosynthesis may have therapeutic potential in chronic inflammatory diseases.
From NAD+ biosynthetic process-Related Genes to Experimental Models
| Research Question | Suitable Model |
|---|---|
| Does loss of NAMPT reduce NAD+ and affect cell survival? | CRISPR knockout in cancer or stem cells |
| Does a specific point mutation in NMNAT1 impair enzyme activity? | Point-mutation knock-in via CRISPR |
| Can restoring NAD+ synthesis rescue a disease phenotype? | Knock-in of wild-type or hyperactive allele |
| Where is NMNAT2 localized in neurons? | Tagged knock-in (e.g., GFP) for imaging |
| Does overexpression of NRK1 enhance NR utilization? | Overexpression cell lines |
| What genes are essential for NAD+ homeostasis? | Genome-wide CRISPR library screening |
How to Study the NAD+ biosynthetic process Process
| Method | What It Measures | Typical Application |
|---|---|---|
| NAD+ cycling assay | Total NAD+ and NADH levels | Quantifying NAD+ in cells and tissues |
| LC-MS/MS | NAD+ and intermediates (NMN, NaMN, NAAD) | Metabolic flux analysis |
| RNA-seq | Expression of NAD+ biosynthetic genes | Transcriptional regulation studies |
| Proteomics | Protein abundance and modifications | Identifying pathway components |
| CRISPR knockout screen | Genes required for NAD+ homeostasis | Discovery of novel regulators |
| CRISPR activation screen | Genes whose overexpression increases NAD+ | Identifying rate-limiting steps |
| Fluorescence microscopy | Subcellular localization of enzymes | Compartmentalization studies |
| NAD+ biosensors | Real-time NAD+ dynamics | Live-cell imaging |
Metabolic and NAD+ quantification
NAD+ and its metabolites can be measured using enzymatic cycling assays, HPLC, or mass spectrometry. These methods quantify total NAD+ and NADH, and can be adapted to measure pathway intermediates like NMN and NaMN.
Transcriptomic and proteomic profiling
RNA-seq and proteomics reveal changes in NAD+ biosynthetic gene expression and protein levels under different conditions. These approaches help identify regulatory networks and compensatory mechanisms.
Genetic screens and CRISPR libraries
CRISPR knockout and activation screens can identify genes that modulate NAD+ levels or sensitivity to NAD+ depletion. Such screens are powerful for discovering novel regulators of GO:0009435.
Imaging and subcellular localization
Fluorescently tagged NAD+ biosynthetic enzymes (e.g., NMNATs) allow visualization of their subcellular distribution and dynamics. Live-cell imaging can track NAD+ changes using genetically encoded biosensors.
How CRISPR Can Be Used to Study GO:0009435 NAD+ biosynthetic process
Knockout
CRISPR knockout of NAD+ biosynthetic genes (e.g., NAMPT, NMNAT1-3) is used to deplete NAD+ and study downstream effects on metabolism, survival, and stress responses. Knockout models help establish whether a gene is essential for maintaining NAD+ levels in specific cell types.
Point Mutation
Point mutations can be introduced to mimic disease-associated variants or to dissect catalytic residues in enzymes like NMNAT1 and NADSYN1. Such models are valuable for understanding how specific mutations affect enzyme activity and NAD+ synthesis.
Knock-in
Knock-in of wild-type or tagged alleles allows precise expression control and visualization of NAD+ biosynthetic enzymes. This approach can also be used to correct disease-causing mutations in patient-derived cells.
Overexpression
Overexpression of rate-limiting enzymes such as NAMPT or NMNATs can boost NAD+ levels and test whether increasing biosynthesis is sufficient to rescue phenotypes. Overexpression models are also used to study feedback regulation.
How EDITGENE Supports NAD+ biosynthetic process Research
Researchers studying NAD+ biosynthetic process-related genes often need to determine whether a candidate gene is causally involved in maintaining NAD+ levels or in disease phenotypes. EDITGENE provides comprehensive CRISPR-based services to generate precise cellular models for such investigations.
Contact EDITGENE today to design your custom CRISPR model for NAD+ biosynthetic process research.
Related Products
| Product name | Cat.No. | Species | Gene ID | |
|---|---|---|---|---|
| KMO Knockout HEK293 Cell Line | EDJ-KQ6289 | Human | 8564 | Details Get a Quote |
| KYNU Knockout HEK293 Cell Line | EDJ-KQ6412 | Human | 8942 | Details Get a Quote |
| NMNAT2 Knockout HEK293 Cell Line | EDJ-KQ7802 | Human | 23057 | Details Get a Quote |
| HAAO Knockout HEK293 Cell Line | EDJ-KQ8031 | Human | 23498 | Details Get a Quote |
| NAPRT Knockout HEK293 Cell Line | EDJ-KQ11164 | Human | 93100 | Details Get a Quote |
| ASPDH Knockout HEK293 Cell Line | EDJ-KQ12458 | Human | 554235 | Details Get a Quote |
| NADSYN1 Knockout HEK293 Cell Line | EDJ-KQ14364 | Human | 55191 | Details Get a Quote |
| NMNAT1 Knockout HEK293 Cell Line | EDJ-KQ14445 | Human | 64802 | Details Get a Quote |
| NMNAT3 Knockout HEK293 Cell Line | EDJ-KQ14446 | Human | 349565 | Details Get a Quote |
| NMRK1 Knockout HEK293 Cell Line | EDJ-KQ14449 | Human | 54981 | Details Get a Quote |
| NAPRT Knockout A-549 Cell Line | EDJ-KQ39179 | Human | 93100 | Details Get a Quote |
| NAPRT Knockout HCT 116 Cell Line | EDJ-KQ39180 | Human | 93100 | Details Get a Quote |
| NAPRT Knockout HeLa Cell Line | EDJ-KQ39181 | Human | 93100 | Details Get a Quote |
| NADSYN1 Knockout A-549 Cell Line | EDJ-KQ44497 | Human | 55191 | Details Get a Quote |
| NADSYN1 Knockout HCT 116 Cell Line | EDJ-KQ44498 | Human | 55191 | Details Get a Quote |
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Frequently Asked Questions About NAD+ biosynthetic process
What is NAD+ biosynthetic process?
NAD+ biosynthetic process (GO:0009435) is the set of chemical reactions and pathways that produce nicotinamide adenine dinucleotide (NAD+) from sources including vitamin B3.
What genes are involved in NAD+ biosynthetic process?
Key genes include NAMPT, NMNAT1-3, NADSYN1, QPRT, NAPRT, NRK1/2, NAXD, and NAXE, among others.
Why is NAD+ biosynthesis important for aging?
NAD+ levels decline with age, and reduced biosynthesis contributes to metabolic and neurodegenerative changes; boosting NAD+ can extend healthspan in models.
How is NAD+ synthesized in cells?
Cells use de novo synthesis from tryptophan, the Preiss-Handler pathway from nicotinic acid, and the salvage pathway from nicotinamide and nicotinamide riboside.
What is the role of NAMPT in NAD+ biosynthesis?
NAMPT is the rate-limiting enzyme in the salvage pathway, converting nicotinamide to NMN, which is then converted to NAD+.
Can CRISPR be used to study NAD+ biosynthesis?
Yes, CRISPR knockout, knock-in, and overexpression models are widely used to dissect gene function in NAD+ metabolism.
What diseases are linked to NAD+ biosynthetic defects?
Defects are linked to aging, metabolic disorders, neurodegeneration, cancer, and rare NAD+ deficiency syndromes.
How can I measure NAD+ levels in cells?
NAD+ can be measured using enzymatic cycling assays, HPLC, or mass spectrometry.
What is the difference between de novo and salvage NAD+ synthesis?
De novo synthesis starts from tryptophan, while salvage recycles nicotinamide; salvage is the primary source in most mammalian cells.
What CRISPR services does EDITGENE offer for NAD+ research?
EDITGENE offers knockout, point mutation, knock-in, overexpression, library screening, and bioinformatics services for NAD+ biosynthetic genes.
Conclusion
GO:0009435 (NAD+ biosynthetic process) is a fundamental metabolic pathway that sustains cellular redox balance and signaling. Its dysregulation is implicated in aging, metabolic diseases, neurodegeneration, and cancer, making it a high-priority research area. CRISPR-based models are indispensable for establishing causal roles of specific genes and for developing therapeutic strategies. EDITGENE provides end-to-end solutions to accelerate discoveries in NAD+ biology.
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. Verdin E. 2015. NAD⁺ in aging, metabolism, and neurodegeneration.. Science 350(6265):1208-13 PMID: 26785480
- 3. Navas LE et al.. 2021. NAD(+) metabolism, stemness, the immune response, and cancer.. Signal Transduct Target Ther 6(1):2 PMID: 33384409
- 4. Katsyuba E et al.. 2020. NAD(+) homeostasis in health and disease.. Nat Metab 2(1):9-31 PMID: 32694684
- 5. Migaud ME et al.. 2024. Regulation of and challenges in targeting NAD(+) metabolism.. Nat Rev Mol Cell Biol 25(10):822-840 PMID: 39026037
- 6. Zapata-Pérez R et al.. 2021. NAD(+) homeostasis in human health and disease.. EMBO Mol Med 13(7):e13943 PMID: 34041853
- 7. Chini CCS et al.. 2021. Evolving concepts in NAD(+) metabolism.. Cell Metab 33(6):1076-1087 PMID: 33930322
- 8. Amjad S et al.. 2021. Role of NAD(+) in regulating cellular and metabolic signaling pathways.. Mol Metab 49:101195 PMID: 33609766
