NOX5 Gene

NOX5 — NADPH Oxidase 5

Introduction

Nox5 Gene is an important component in the neurobiology of neurodegenerative diseases. This page provides detailed information about its structure, function, and role in disease processes.

Overview

NOX5 (NADPH Oxidase 5) is a gene located on chromosome 15q21.3 that encodes NADPH oxidase 5, a member of the NADPH oxidase (NOX) family of enzymes that generate [reactive oxygen species](/entities/reactive-oxygen-species) (ROS)[@banfi2001]. NOX5 is unique among NOX isoforms because it contains calcium-binding EF-hand domains at its N-terminus, making it directly activated by calcium rather than by protein kinase C phosphorylation.

In [neurons](/entities/neurons), NOX enzymes contribute to oxidative stress, which is a key pathological feature of neurodegenerative diseases. NOX5-mediated ROS production has been implicated in neuronal death pathways in Alzheimer's disease and Parkinson's disease[@bedard2007][@querfurth2010].

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NOX5 — NADPH Oxidase 5

Introduction

Nox5 Gene is an important component in the neurobiology of neurodegenerative diseases. This page provides detailed information about its structure, function, and role in disease processes.

Overview

NOX5 (NADPH Oxidase 5) is a gene located on chromosome 15q21.3 that encodes NADPH oxidase 5, a member of the NADPH oxidase (NOX) family of enzymes that generate [reactive oxygen species](/entities/reactive-oxygen-species) (ROS)[@banfi2001]. NOX5 is unique among NOX isoforms because it contains calcium-binding EF-hand domains at its N-terminus, making it directly activated by calcium rather than by protein kinase C phosphorylation.

In [neurons](/entities/neurons), NOX enzymes contribute to oxidative stress, which is a key pathological feature of neurodegenerative diseases. NOX5-mediated ROS production has been implicated in neuronal death pathways in Alzheimer's disease and Parkinson's disease[@bedard2007][@querfurth2010].

<div class="infobox infobox-gene">
<table>
<tr><th colspan="2" style="background:#e8f4f8; text-align:center; font-size:1.1em;">NADPH Oxidase 5</th></tr>
<tr><td><strong>Gene Symbol</strong></td><td>NOX5</td></tr>
<tr><td><strong>Full Name</strong></td><td>NADPH Oxidase 5</td></tr>
<tr><td><strong>Chromosome</strong></td><td>15q21.3</td></tr>
<tr><td><strong>NCBI Gene ID</strong></td><td>[79400](https://www.ncbi.nlm.nih.gov/gene/79400)</td></tr>
<tr><td><strong>OMIM</strong></td><td>607610</td></tr>
<tr><td><strong>Ensembl ID</strong></td><td>ENSG00000195226</td></tr>
<tr><td><strong>UniProt ID</strong></td><td>[Q96PH1](https://www.uniprot.org/uniprot/Q96PH1)</td></tr>
<tr><td><strong>Associated Diseases</strong></td><td>Alzheimer's Disease, Parkinson's Disease, Cardiovascular Disease</td></tr>
</table>
</div>

Gene Structure and Protein Domains

NOX5 encodes a protein of approximately 755 amino acids with a molecular weight of ~93 kDa. The protein contains several distinctive domains:

• N-terminal EF-hand domains (4×): Calcium-binding motifs that sense intracellular calcium concentrations
• Transmembrane domains (6×): Anchor the protein to cellular membranes
• dehydrogenase domain: FAD and NADPH binding site for electron transfer
• C-terminal region: Contains the heme-binding pocket

Unlike other NOX isoforms (NOX1-4), NOX5 does not require phosphorylation for activation but is directly activated by calcium binding to its EF-hand domains[@banfi2001].

Normal Physiological Function

ROS Production

NOX5 generates superoxide anion (O₂⁻) by transferring electrons from NADPH to molecular oxygen:

NADPH + O₂ → NADP⁺ + O₂⁻ + H⁺

The superoxide produced can be converted to other reactive oxygen species:

• Superoxide dismutase (SOD): Converts O₂⁻ to H₂O₂
• Myeloperoxidase: Converts H₂O₂ to hypochlorous acid (HOCl)

Tissue Distribution

NOX5 is highly expressed in:

• Lymphoid tissues (spleen, thymus, lymph nodes)
• Testis
• Ovary
• Vascular smooth muscle cells
• Platelets

In the brain, NOX5 expression is relatively low compared to other NOX isoforms (NOX1, NOX2, NOX4), but it has been detected in neurons and glial cells[@bedard2007].

Role in Neurodegeneration

Alzheimer's Disease

NOX5 contributes to Alzheimer's disease pathogenesis through multiple mechanisms:

Calcium dysregulation: [Aβ](/proteins/amyloid-beta) oligomers can increase intracellular calcium levels, which directly activates NOX5

Oxidative stress: Increased ROS production leads to lipid peroxidation, protein oxidation, and DNA damage

Synaptic dysfunction: ROS can impair synaptic plasticity and neurotransmitter release

Neuroinflammation: NOX5 activation in [microglia](/cell-types/microglia-neuroinflammation) can amplify inflammatory responses

The calcium hypothesis of AD proposes that dysregulated calcium signaling is an early event in AD pathogenesis. Since NOX5 is calcium-activated, this provides a direct link between calcium dysregulation and oxidative stress in AD[@querfurth2010][@sorce2014].

Parkinson's Disease

In Parkinson's disease, NOX5 may contribute to:

Dopaminergic neuron vulnerability: The substantia nigra pars compacta has high basal metabolic activity and is particularly vulnerable to oxidative stress

[α-Synuclein](/proteins/alpha-synuclein) aggregation: Oxidative stress can promote α-synuclein misfolding and aggregation

Mitochondrial dysfunction: ROS can damage mitochondrial complex I, exacerbating PD pathology

Neuroinflammation: Activated microglia express NOX enzymes that contribute to dopaminergic neuron death[@gao2012]

Other Neurodegenerative Conditions

• Amyotrophic Lateral Sclerosis (ALS): NOX5-mediated ROS may contribute to motor neuron death
• Multiple Sclerosis: NOX5 in immune cells may exacerbate demyelination
• Huntington's Disease: Oxidative stress from NOX5 may accelerate [htt](/proteins/huntingtin) protein aggregation

Signaling Pathways

Activation Mechanisms

NOX5 is activated by:

Calcium influx: Through voltage-gated calcium channels, NMDA receptors, or IP₃ receptor-gated stores

Calmodulin: Calcium-bound calmodulin can enhance NOX5 activity

Phosphorylation: While not required, PKC phosphorylation can modulate activity

Downstream Effects

• [NF-κB](/entities/nf-kb) activation → pro-inflammatory gene expression
• MAPK pathway activation → cell stress responses
• Caspase activation → [apoptosis](/entities/apoptosis)
• JNK/p38 pathways → neuronal death

Therapeutic Implications

NOX5 Inhibitors

Several NOX inhibitors have been developed that may have therapeutic potential:

| Compound | Mechanism | Development Stage |
|----------|-----------|-------------------|
| GKT137831 | NOX1/NOX4 inhibitor | Phase 2 trials |
| VAS2870 | Pan-NOX inhibitor | Preclinical |
| Fulvene-5 | NOX5 inhibitor | Preclinical |

Combination Approaches

• NOX inhibitors + antioxidants: May provide synergistic neuroprotection
• Calcium channel blockers + NOX inhibitors: Target both calcium dysregulation and oxidative stress
• Anti-inflammatory + NOX inhibition: Reduce neuroinflammation-driven ROS production

Biomarkers

NOX5 activity can be assessed through:

• Direct markers: Superoxide production assays, ROS-sensitive dyes
• Indirect markers: 8-OHdG (DNA oxidation), 4-HNE (lipid peroxidation), protein carbonyls
• Genetic markers: NOX5 polymorphisms may influence disease risk

Interaction Network

Protein-Protein Interactions

• Calmodulin: Calcium-dependent activator
• p67phox: Regulatory subunit homolog (NOX5-specific regulator)
• Hsp90: Chaperone for proper folding

Signaling Crosstalk

• NMDAR: Calcium influx through NMDA receptors activates NOX5
• mGluR: Metabotropic glutamate receptors linked to NOX5 activation
• [RAGE](/entities/rage-receptor): Receptor for advanced glycation end-products upregulates NOX5

See Also

• [Oxidative Stress](/mechanisms/oxidative-stress)
• [Calcium Signaling in Neurodegeneration](/mechanisms/calcium-dysregulation)
• [Neuroinflammation Pathway](/mechanisms/neuroinflammation)
• [Mitochondrial Dysfunction in AD](/mechanisms/mitochondrial-dysfunction-alzheimers)
• [Parkinson's Disease Mechanisms](/diseases/parkinsons-disease-mechanisms)
• [NOX Family in Brain](/mechanisms/nadh-phosphates-oxidase-family)

Background

The study of Nox5 Gene has evolved significantly over the past decades. Research in this area has revealed important insights into the underlying mechanisms of neurodegeneration and continues to drive therapeutic development.

Historical context and key discoveries in this field have shaped our current understanding and will continue to guide future research directions.

External Links

• [NCBI Gene - NOX5](https://www.ncbi.nlm.nih.gov/gene/79400)
• [UniProt - NOX5 (Q96PH1)](https://www.uniprot.org/uniprot/Q96PH1)
• [Ensembl - NOX5](https://www.ensembl.org/Homo_sapiens/Gene/Summary?g=ENSG00000195226)
• [OMIM - NOX5](https://www.omim.org/entry/607610)

References

[Banfi et al., A novel H2O2-forming NADPH oxidase family expressed in phagocytes (2001) (2001)](https://doi.org/10.1074/jbc.M106781200)

[Unknown, Bedard & Krause, The NOX family of ROS-generating NADPH oxidases (2007) (2007)](https://doi.org/10.1152/physiol.00044.2006)

[Unknown, Querfurth & LaFerla, Calcium hypothesis of Alzheimer's disease (2010) (2010)](https://doi.org/10.1056/NEJMra0911533)

[Sorce et al., NADPH oxidases in neurological diseases (2014) (2014)](https://doi.org/10.1016/j.tips.2014.01.004)

[Gao et al., NOX in neurodegeneration (2012) (2012)](https://doi.org/10.1016/j.bbadis.2012.02.019)

[Khalil et al., NOX5 and calcium signaling in cardiovascular disease (2015) (2015)](https://doi.org/10.1016/j.yjmcc.2015.06.012)

[Miller et al., Redox signaling in neurological diseases (2013) (2013)](https://doi.org/10.1016/j.neuropharm.2012.08.012)

[Wang et al., NOX5 contributes to Aβ-induced neuronal oxidative stress (2020) (2020)](https://doi.org/10.1016/j.neurobiolaging.2020.03.012)