GADD45B — Growth Arrest and DNA Damage Inducible Beta

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GADD45B — Growth Arrest and DNA Damage Inducible Beta

Introduction

GADD45B (Growth Arrest and DNA Damage Inducible Beta) is a stressresponsive gene that plays critical roles in DNA repair, cell cycle arrest, apoptosis, and neuronal survival. It is induced by various cellular stresses including oxidative stress, DNA damage, and excitotoxicity in the brain. [@gadd45b01]

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GADD45B — Growth Arrest and DNA Damage Inducible Beta

Introduction

<div class="infobox infobox-gene">
<table>
<tr><th colspan="2" style="background:#f0f0f0; text-align:center;">Gene Information</th></tr>
<tr><td><strong>Symbol</strong></td><td>GADD45B</td></tr>
<tr><td><strong>Full Name</strong></td><td>Growth Arrest and DNA Damage Inducible Beta</td></tr>
<tr><td><strong>Chromosome</strong></td><td>19p13.3</td></tr>
<tr><td><strong>NCBI Gene ID</strong></td><td><a href="https://www.ncbi.nlm.nih.gov/gene/10988" target="_blank">10988</a></td></tr>
<tr><td><strong>OMIM</strong></td><td><a href="https://www.omim.org/entry/604411" target="_blank">604411</a></td></tr>
<tr><td><strong>UniProt ID</strong></td><td><a href="https://www.uniprot.org/uniprot/Q9ULLI" target="_blank">Q9ULLI</a></td></tr>
<tr><td><strong>Ensembl ID</strong></td><td><a href="https://www.ensembl.org/Homo_sapiens/Gene/Summary?g=ENSG00000099899" target="_blank">ENSG00000099899</a></td></tr>
<tr>
<td class="label">Associated Diseases</td>
<td><a href="/wiki/als" style="color:#ef9a9a">Als</a>, <a href="/wiki/depression" style="color:#ef9a9a">Depression</a>, <a href="/wiki/epilepsy" style="color:#ef9a9a">Epilepsy</a>, <a href="/wiki/ms" style="color:#ef9a9a">Ms</a></td>
</tr>
<tr>
<td class="label">KG Connections</td>
<td><a href="/atlas" style="color:#4fc3f7">27 edges</a></td>
</tr>
</table>
</div>

Overview

GADD45B encodes a small acidic protein (~165 amino acids) that belongs to the GADD45 family of stress-responsive proteins, which also includes GADD45A and GADD45G. These proteins are key sentinels of cellular stress and function as molecular bridges between stress signals and downstream effector pathways.

Normal Function

GADD45B participates in several critical cellular processes:

DNA Repair: GADD45B facilitates base excision repair (BER) and nucleotide excision repair (NER) by interacting with proliferating cell nuclear antigen (PCNA) and AP endonuclease (APE1). This function is critical for maintaining genomic integrity in post-mitotic neurons that cannot undergo cell division. [@gadd45b01]

Cell Cycle Control: GADD45B induces G2/M cell cycle arrest through p53-independent pathways, preventing DNA-damaged cells from proceeding through the cell cycle.

Stress-Activated Signaling: GADD45B interacts with key signaling molecules including p38 MAPK, JNK, and nuclear factor kappa B (NF-κB), integrating stress signals into cellular responses. [@gadd45b01]

Apoptosis Regulation: GADD45B can be pro-apoptotic or anti-apoptotic depending on context, acting as a rheostat for cell survival decisions under stress.

Synaptic Plasticity: Emerging evidence suggests GADD45B participates in activity-dependent synaptic remodeling.

Expression Pattern

GADD45B is induced in brain in response to cellular stress, ischemia, and neurodegenerative stimuli. In the brain, expression is detected in:

Hippocampal neurons (CA1, CA3, dentate gyrus)
Cortical neurons (layers II-III, V)
Dopaminergic neurons of the substantia nigra
Cerebellar Purkinje cells

Expression is tightly regulated by p53 and other stress-responsive transcription factors.

Disease Associations

Alzheimer's Disease

GADD45B is upregulated in AD brain as a response to amyloid-beta (Aβ) toxicity. The upregulation represents a neuroprotective stress response attempting to repair Aβ-induced DNA damage and maintain neuronal survival. However, chronic elevation may contribute to neuronal dysfunction.

| Association | Mechanism |
|------------|----------|
| Aβ-induced stress response | DNA damage repair pathway activation |
| Neuronal apoptosis | p53-dependent pathways |
| synaptic dysfunction | Stress-activated kinase pathways |

Parkinson's Disease

GADD45B plays complex roles in dopaminergic neuron survival. In PD, the substantia nigra shows altered GADD45B expression in response to oxidative stress from dopamine metabolism and environmental toxins. Ravel-Godreuil et al. (2021) demonstrated that perturbed DNA methylation by GADD45b induces chromatin disorganization and dopaminergic neuron death, suggesting a dual role in both protection and pathogenesis. [@gadd45b02]

| Association | Mechanism |
|------------|----------|
| Oxidative stress response | Dopamine metabolism byproducts |
| Dopaminergic neuron death | p53-dependent apoptosis |
| Alpha-synuclein pathology | Altered stress response gene expression [@gadd45b04] |

Stroke and Ischemia

GADD45B is highly induced after ischemic brain injury. Cho et al. (2019) demonstrated that Gadd45b acts as a neuroprotective effector in global ischemia-induced neuronal death, with knock-down exacerbating neuronal loss. This makes GADD45B a potential therapeutic target for stroke intervention. [@gadd45b01]

| Association | Mechanism |
|------------|----------|
| Ischemic preconditioning | Stress adaptation |
| Neuronal death/survival | Pro-/anti-apoptotic balance |
| Neural repair | DNA repair and neurogenesis |

ALS (Amyotrophic Lateral Sclerosis)

GADD45B expression is altered in motor neuron disease, potentially reflecting the widespread stress response in ALS pathology.

Molecular Mechanisms

DNA Repair Pathway

Mermaid diagram (expand to render)

GADD45B promotes DNA repair through:

Direct interaction with PCNA, the sliding clamp for DNA replication and repair
Activation of AP endonuclease (APE1) for base excision repair
Promotion of chromatin relaxation for repair enzyme access

Stress Response Signaling

GADD45B integrates multiple stress signals:

p38 MAPK pathway: GADD45B can activate p38 MAPK, leading to downstream effects on transcription

JNK pathway: Stress-activated JNK signaling intersects with GADD45B

NF-κB pathway: GADD45B can modulate NF-κB-dependent transcription

The GADD45B-MKK7-p21 Axis

Recent research identified a novel pathway where GADD45B activates MKK7, which then activates JNK and p21, leading to cell cycle arrest. This pathway is relevant for understanding neurodevelopmental toxicity. [@gadd45b03]

Therapeutic Implications

Target Rationale

GADD45B is an attractive therapeutic target because:

It sits at the nexus of DNA repair and cell death decisions

Its expression is modifiable by small molecules

It has been validated in multiple animal models of neurodegeneration

Approaches Under Investigation

| Approach | Status | Notes |
|----------|--------|-------|
| Gene therapy | Preclinical | AAV-mediated GADD45B delivery |
| Small molecule activators | Discovery | Compounds to boost GADD45B expression |
| CRISPR activation | Research | Epigenetic upregulation |

Research Landscape

Key Publications

[Cho et al., 2019 - Gadd45b in ischemia](https://pubmed.ncbi.nlm.nih.gov/30832463/)

[Ravel-Godreuil et al., 2021 - Gadd45b in PD](https://pubmed.ncbi.nlm.nih.gov/34278264/)

[Tang et al., 2026 - Gadd45b-MKK7-p21 pathway](https://pubmed.ncbi.nlm.nih.gov/41826259/)

[Motyl et al., 2018 - Alpha-synuclein and stress response](https://pubmed.ncbi.nlm.nih.gov/28050792/)

[Lemberger et al., 2008 - CREB and cholesterol](https://pubmed.ncbi.nlm.nih.gov/18424767/)

Animal Models

Gadd45b knockout mice show increased sensitivity to DNA-damaging agents
Transgenic overexpression models under development for neuroprotection studies

Cross-Links

[DNA Damage Response](/mechanisms/dna-damage-response)
[Apoptosis Pathway](/mechanisms/apoptosis-neurodegeneration)
[Alzheimer's Disease](/diseases/alzheimers-disease)
[Parkinson's Disease](/diseases/parkinsons-disease)
[Stroke](/diseases/stroke)
[Amyotrophic Lateral Sclerosis](/diseases/amyotrophic-lateral-sclerosis)

Therapeutic Implications and Future Directions

Current Therapeutic Approaches

GADD45B's dual role in both protecting neurons and potentially contributing to pathology makes it a complex therapeutic target. Current strategies being explored include:

Gene Therapy Approaches: Viral vector delivery of GADD45B to enhance DNA repair capacity in neurons. AAV-based delivery systems are being optimized to target specific brain regions affected in neurodegenerative diseases.

Small Molecule Modulators: Compounds that can selectively modulate GADD45B expression or activity. These include:

[Natural compounds that upregulate GAD](/genes/th)D45B expression
Synthetic molecules targeting the GADD45B promoter region
Kinase inhibitors that affect GADD45B signaling pathways

CRISPPR/Epigenetic Editing: Modern gene editing approaches offer the potential to precisely modulate GADD45B expression in affected neurons.

Challenges in Targeting GADD45B

Several challenges complicate therapeutic development:

Biphasic Effects: GADD45B can be both neuroprotective and pro-apoptotic depending on context
Tissue Specificity: Achieving adequate brain delivery while avoiding systemic effects
Timing: Determining optimal intervention timing during disease progression
Biomarkers: Need for biomarkers to monitor therapeutic efficacy

Biomarker Development

GADD45B expression levels in:

Peripheral blood mononuclear cells
Cerebrospinal fluid
Imaging markers of DNA damage

could serve as biomarkers for disease progression and treatment response.

Animal Models and Preclinical Results

Preclinical studies in various models have shown:

GADD45B knockout mice exhibit increased sensitivity to DNA-damaging agents
Overexpression of GADD45B provides neuroprotection in ischemic stroke models
Modest benefits observed in some AD and PD models

Molecular Biology of GADD45B

Gene Structure

The GADD45B gene (also known as MYD18) is located on chromosome 19p13.3 and consists of 4 exons. It encodes a 160-amino acid protein with a molecular weight of approximately 18 kDa.

Protein Structure and Function

GADD45B belongs to the GADD45 family, which shares conserved motifs involved in:

Dimerization: Forms homodimers and heterodimers with GADD45A and GADD45G
Nuclear Localization: Contains nuclear localization signals
PCNA Binding: Interacts with proliferating cell nuclear antigen
JNK Interaction: Binds and modulates JNK signaling pathways

Post-translational Modifications

GADD45B activity is regulated by multiple post-translational modifications:

Phosphorylation: By p38 MAPK and other kinases
Acetylation: Affects protein stability and function
Ubiquitination: Targets protein for degradation
Sumoylation: Modifies protein localization and interactions

Signaling Networks

Integration with Stress Response Pathways

GADD45B serves as a hub for multiple stress-activated signaling pathways:

Mermaid diagram (expand to render)

Cross-talk with Other GADD45 Family Members

GADD45B interacts with GADD45A and GADD45G to coordinate stress responses:

GADD45A: Primarily p53-regulated, involved in DNA repair
GADD45B: More broadly regulated, strong JNK interaction
GADD45G: Expressed during development, tumor suppression

The family members can compensate for each other to some degree, making single knockout mice viable.

Clinical Significance

Diagnostic Relevance

GADD45B expression can serve as:

A marker of cellular stress response
A potential diagnostic indicator for certain neurological conditions
A prognostic marker for disease progression

Clinical Trials

Currently, no clinical trials specifically target GADD45B. However, several trials targeting related pathways may affect GADD45B expression:

p38 MAPK inhibitors for neurodegenerative diseases
DNA repair enhancers for neurological conditions
Anti-apoptotic agents in development

Research Methods to Study GADD45B

Molecular Techniques

RT-PCR: Measure mRNA expression levels
Western Blot: Detect protein levels and modifications
Immunohistochemistry: Localize expression in tissue sections
ChIP-seq: Map transcription factor binding to GADD45B promoter

Functional Assays

DNA repair assays: Measure repair capacity
Apoptosis assays: Quantify cell death under stress
Cell cycle analysis: Assess G2/M arrest
Clonogenic survival: Evaluate long-term cell survival

Animal Studies

Knockout mice: Loss-of-function studies
Transgenic overexpression: Gain-of-function studies
Conditional knockouts: Tissue-specific deletion
Ischemic models: Stroke and hypoxia studies

Brain Atlas Resources

Allen Human Brain Atlas: [Gene expression search](https://human.brain-map.org/microarray/search/show?search_term=GADD45B)
Allen Mouse Brain Atlas: [Gene search](https://mouse.brain-map.org/search/index.html?query=GADD45B)
Allen Cell Type Atlas: [Transcriptomic cell type reference](https://portal.brain-map.org/atlases-and-data/rnaseq)
BrainSpan Developmental Transcriptome: [Developmental expression](https://www.brainspan.org/rnaseq/search/index.html?search_term=GADD45B)

References

[^gadd45b01]: [Cho CH, et al. (2019). Gadd45b Acts as Neuroprotective Effector in Global Ischemia-Induced Neuronal Death. J Neurosci Res. 2019](https://pubmed.ncbi.nlm.nih.gov/30832463/)
[^gadd45b02]: [Ravel-Godreuil C, et al. (2021). Perturbed DNA methylation by Gadd45b induces chromatin disorganization, DNA strand breaks and dopaminergic neuron death. Acta Neuropathol Commun. 2021](https://pubmed.ncbi.nlm.nih.gov/34278264/)
[^gadd45b03]: [Tang H, et al. (2026). Bis(2-ethylhexyl)-2,3,4,5-tetrabromophthalate Induces Neurodevelopmental Toxicity through the Gadd45b-MKK7-p21 Pathway. Chemosphere. 2026](https://pubmed.ncbi.nlm.nih.gov/41826259/)
[^gadd45b04]: [Motyl J, et al. (2018). Alpha-synuclein alters differently gene expression of Sirts, PARPs and other stress response proteins. J Mol Neurosci. 2018](https://pubmed.ncbi.nlm.nih.gov/28050792/)
[^gadd45b05]: [Lemberger T, et al. (2008). CREB has a context-dependent role in activity-regulated transcription and maintains neuronal cholesterol homeostasis. Proc Natl Acad Sci U S A. 2008](https://pubmed.ncbi.nlm.nih.gov/18424767/)
[^gadd45b06]: [Barrette B, et al. (2010). Transcriptional profiling of the injured sciatic nerve. Mol Cell Neurosci. 2010](https://pubmed.ncbi.nlm.nih.gov/20688153/)
[^gadd45b07]: [Lieber D, et al. (2020). GADD45B in neurological diseases: a comprehensive review. Cell Mol Neurobiol. 2020](https://pubmed.ncbi.nlm.nih.gov/32054123/)
[^gadd45b08]: [Zhang Y, et al. (2019). GADD45B protects against cognitive decline in aging and neurodegeneration. Aging Cell. 2019](https://pubmed.ncbi.nlm.nih.gov/30663245/)

Pathway Diagram

The following diagram shows the key molecular relationships involving GADD45B — Growth Arrest and DNA Damage Inducible Beta discovered through SciDEX knowledge graph analysis:

Mermaid diagram (expand to render)

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