KDM3B - Lysine Specific Demethylase 3B
<table class="infobox infobox-gene">
<tr>
<th class="infobox-header" colspan="2">KDM3B</th>
</tr>
<tr>
<td class="label">Gene Symbol</td>
<td>KDM3B</td>
</tr>
<tr>
<td class="label">Full Name</td>
<td>Lysine Specific Demethylase 3B</td>
</tr>
<tr>
<td class="label">Chromosomal Location</td>
<td>5q31.1</td>
</tr>
<tr>
<td class="label">NCBI Gene ID</td>
<td>55693</td>
</tr>
<tr>
<td class="label">Ensembl ID</td>
<td>ENSG00000106479</td>
</tr>
<tr>
<td class="label">OMIM ID</td>
<td>607395</td>
</tr>
<tr>
<td class="label">UniProt ID</td>
<td>Q7Z6W4</td>
</tr>
<tr>
<td class="label">Associated Diseases</td>
<td>[Alzheimer's Disease](/diseases/alzheimers-disease), Depression, Neurodevelopmental Disorders</td>
</tr>
<tr>
<td class="label">Protein Family</td>
<td>JHDM3/KDM3 family (Jumonji C domain demethylase)</td>
</tr>
</table>
KDM3B (Lysine Specific Demethylase 3B)
Introduction
Mermaid diagram (expand to render)
KDM3B (also known as JHDM3A or JMJD1A) is a Jumonji C (JmjC) domain-containing histone demethylase that catalyzes the removal of methyl groups from histone lysine residues. This enzyme belongs to the JHDM3/KDM3 family and plays important roles in chromatin remodeling, gene expression regulation, and cellular metabolism. [@cheng2023] Recent research has revealed important functions for KDM3B in neurodevelopment, mood regulation, and neurodegenerative processes, making it a gene of interest for understanding [Alzheimer's Disease](/diseases/alzheimers-disease) and related disorders. [@chen2022]
Molecular Function
Catalytic Activity
KDM3B is a Fe(II)- and 2-oxoglutarate-dependent dioxygenase that demethylates:
- H3K9me1/2: Primary substrate — demethylation activates gene expression
- H3K9me3: Also targeted, particularly in transcriptional activation
- H3K27me2: Secondary substrate with lesser activity
The JmjC domain serves as the catalytic center, coordinating Fe(II) and binding 2-oxoglutarate as a co-substrate. The reaction produces succinate and CO2 as byproducts. Unlike KDM1A (which uses FAD), KDM3B utilizes a distinct mechanism shared with other JmjC-domain demethylases. [@kooistra2012]
Substrate Specificity
KDM3B shows relatively broad specificity for H3K9 methylation states:
- Efficiently removes H3K9me1 and H3K9me2
- Can also demethylate H3K9me3, though less efficiently
- Activity toward other histone residues is minimal
This substrate profile makes KDM3B primarily a transcriptional activator when targeting H3K9me1/2 at gene promoters and enhancers. [@whitelaw2020]
Biological Functions
KDM3B was originally characterized as a regulator of energy homeostasis:
- PPARγ activation: KDM3B demethylates H3K9me2 at [PPARGC1A](/genes/ppargc1a) (PGC-1α) promoter, activating mitochondrial biogenesis
- Adipogenesis: Regulates genes involved in fat cell differentiation
- Thermogenesis: Controls brown adipose tissue function
Studies in knockout mice demonstrate that KDM3B deficiency leads to obesity and impaired energy expenditure. [@tateishi2009]
Transcriptional Regulation
KDM3B regulates diverse transcriptional programs:
- Nuclear hormone receptors: Activates androgen receptor and retinoic acid receptor target genes
- Hypoxia response: Regulates HIF-1α target genes under low oxygen conditions
- Metabolic genes: Controls expression of gluconeogenic and lipogenic enzymes
The enzyme often functions as a coactivator, recruited by transcription factors to remove repressive H3K9me2 marks. [@lee2020]
Role in the Nervous System
Neurodevelopment
During neural development, KDM3B contributes to:
- Neural progenitor differentiation: Regulates genes necessary for neuronal lineage commitment
- Cortical development: Controls proper layering of the cerebral cortex
- Synaptogenesis: Influences synapse formation and plasticity
Research demonstrates that KDM3B is essential for proper neuronal differentiation and chromatin remodeling during brain development. [@kim2019]
Mood and Behavior
KDM3B has been implicated in mood regulation and stress responses:
- Depression: Altered KDM3B expression in prefrontal cortex of depressed individuals
- Stress response: Regulates hypothalamic-pituitary-adrenal (HPA) axis activity
- Antidepressant effects: Some antidepressant treatments may work through KDM3B modulation
Human genetic studies have linked KDM3B polymorphisms with susceptibility to major depressive disorder. [@inoue2018][@goto2018]
Disease Associations
Alzheimer's Disease
Emerging evidence suggests KDM3B involvement in AD:
- Epigenetic dysregulation: Altered H3K9 methylation patterns in AD brain
- Gene expression changes: Dysregulation of metabolic and synaptic genes
- Therapeutic potential: Modulating KDM3B activity may restore proper gene expression
Preclinical models show that KDM3B dysfunction contributes to neurodegenerative processes through epigenetic mechanisms. [@chen2022]
Neurodevelopmental Disorders
KDM3B variants are associated with:
- Intellectual disability
- Developmental delay
- Autism spectrum features
The enzyme's role in regulating developmental gene expression programs makes it a candidate for neurodevelopmental disease genes. [@iwase2016]
Expression Pattern
KDM3B is expressed in multiple brain regions:
- Hippocampus: Dentate gyrus and CA regions
- Cerebral cortex: All layers
- Hypothalamus: Paraventricular nucleus
- Amygdala: Central and basal nuclei
Expression is regulated by neuronal activity and hormonal signals, suggesting dynamic control of chromatin states in response to environmental cues. [@huang2019]
Therapeutic Implications
Drug Development
KDM3B is being explored as a therapeutic target:
- Cancer therapy: KDM3B inhibitors in development for various cancers
- Metabolic disorders: Activators may treat obesity and metabolic syndrome
- Neuropsychiatric indications: Modulators may have antidepressant potential
The challenge is achieving brain-penetrant, selective compounds that can modulate KDM3B activity in the central nervous system. [@lee2020]
Interactions and Pathways
Key Protein Interactions
| Partner | Function |
|---------|----------|
| [PPARGC1A](/genes/ppargc1a) | Metabolic gene coactivation |
| [HIF-1A](/genes/hif1a) | Hypoxia response |
| [AR](/genes/ar) | Nuclear receptor coactivation |
| [STAT3](/genes/stat3) | Cytokine signaling |
Signaling Pathways
- PPAR signaling: KDM3B as coactivator
- Hypoxia-inducible factor (HIF) pathway: Regulates oxygen response genes
- cAMP/PKA signaling: Activity-dependent regulation
- MAPK pathway: Growth factor signaling
See Also
- [Epigenetic Regulation in Neurodegeneration](/mechanisms/epigenetic-regulation-neurodegeneration)
- [Histone Modifications](/mechanisms/histone-modifications)
- [Jumonji C Domain Demethylases](/mechanisms/jumonji-demethylases)
- [Alzheimer's Disease - Molecular Mechanisms](/diseases/alzheimers-disease)
- [Depression and Neurodegeneration](/diseases/depression)
- [Genes - Index](/genes)
- [Proteins - Index](/proteins)