ZDHHC8 — Zinc Finger DHHC-Type Palmitoyltransferase 8
<table class="infobox infobox-gene">
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<th class="infobox-header" colspan="2">ZDHHC8 — Zinc Finger DHHC-Type Palmitoyltransferase 8</th>
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<td class="label">Symbol</td>
<td><strong>ZDHHC8</strong></td>
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<td class="label">Full Name</td>
<td>Zinc Finger DHHC-Type Palmitoyltransferase 8</td>
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<td class="label">Chromosome</td>
<td>22q11.21</td>
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<td class="label">NCBI Gene</td>
<td><a href="https://www.ncbi.nlm.nih.gov/gene/57103" target="_blank">57103</a></td>
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<td class="label">Ensembl</td>
<td><a href="https://ensembl.org/Homo_sapiens/Gene/Summary?g=ENSG00000140995" target="_blank">ENSG00000140995</a></td>
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<td class="label">OMIM</td>
<td><a href="https://omim.org/entry/611415" target="_blank">611415</a></td>
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<td class="label">UniProt</td>
<td><a href="https://www.uniprot.org/uniprot/Q9NXK5" target="_blank">Q9NXK5</a></td>
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<td class="label">Diseases</td>
<td><a href="/diseases/schizophrenia">Schizophrenia</a>, <a href="/diseases/22q11-2-deletion-syndrome">22q11.2 Deletion Syndrome</a>, <a href="/diseases/bipolar-disorder">Bipolar Disorder</a></td>
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<td class="label">Expression</td>
<td>Brain (Cortex, Hippocampus, Cerebellum), Neurons</td>
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<td class="label">Associated Diseases</td>
<td><a href="/wiki/aging" style="color:#ef9a9a">Aging</a>, <a href="/wiki/cancer" style="color:#ef9a9a">Cancer</a>, <a href="/wiki/ischemia" style="color:#ef9a9a">Ischemia</a>, <a href="/wiki/ms" style="color:#ef9a9a">Ms</a>, <a href="/wiki/neurodegeneration" style="color:#ef9a9a">Neurodegeneration</a></td>
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<td class="label">KG Connections</td>
<td><a href="/atlas" style="color:#4fc3f7">24 edges</a></td>
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</table>
ZDHHC8 — Zinc Finger DHHC-Type Palmitoyltransferase 8
Introduction
Mermaid diagram (expand to render)
ZDHHC8 (Zinc Finger DHHC-Type Palmitoyltransferase 8) is a critical enzyme that catalyzes S-acylation (palmitoylation) of proteins, a reversible post-translational modification essential for protein trafficking, localization, and function in neurons. As a member of the zinc finger DHHC (Asp-His-His-Cys)-type containing protein family, ZDHHC8 plays a fundamental role in neuronal development, synaptic function, and neurotransmission. Notably, ZDHHC8 is located within the 22q11.2 chromosomal deletion region, one of the most common copy number variations in humans, which confers significant risk for schizophrenia, bipolar disorder, and other neurodevelopmental disorders.
Palmitoylation is unique among post-translational modifications due to its reversibility, allowing dynamic regulation of protein localization and function in response to cellular signals. This stands in contrast to other lipid modifications like myristoylation or prenylation, which are generally irreversible. The dynamic nature of palmitoylation makes it particularly important in neuronal signaling, where rapid changes in protein localization and function are required for synaptic plasticity, learning, and memory.
Gene Structure and Protein Biology
Genomic Organization
ZDHHC8 is located on chromosome 22q11.21, within the 22q11.2 deletion syndrome critical region. This location is significant because the 22q11.2 deletion, affecting approximately 1 in 4,000 live births, is one of the most common chromosomal deletion syndromes and includes ZDHHC8 as one of approximately 60-70 genes haploinsufficient in this region.
Protein Structure
ZDHHC8 encodes a protein palmitoyltransferase containing several key structural features:
DHHC domain: The signature zinc finger DHHC domain (Asp-His-His-Cys) that catalyzes palmitoylation
Ankyrin repeats: Mediate protein-protein interactions
TM domains: Multiple transmembrane helices that localize the enzyme to intracellular membranes
ER retrieval signal: Maintains localization to the endoplasmic reticulum and GolgiCatalytic Mechanism
ZDHHC8 catalyzes palmitoylation through a two-step mechanism:
Acyl-CoA binding: Palmitoyl-CoA binds to the DHHC domain
Thioester formation: The palmitoyl group is transferred to a cysteine residue on the substrate protein
Product release: The palmitoylated protein is releasedThis reaction is reversible, with depalmitoylases (such as ABHD17A) catalyzing the reverse reaction, allowing dynamic control of protein palmitoylation status.
Expression Patterns
Brain Distribution
ZDHHC8 exhibits high expression in brain regions critical for cognition and emotion:
- Cerebral cortex: Highest expression in pyramidal neurons
- Hippocampus: Particularly in CA1-CA3 pyramidal cells and dentate gyrus
- Cerebellum: Purkinje cells show significant expression
- Amygdala: Neurons involved in emotional processing
- Thalamus: Relay neurons
Cellular Localization
Within neurons, ZDHHC8 is primarily localized to:
- Endoplasmic reticulum: Main site of palmitoylation catalysis
- Golgi apparatus: Further processing and sorting
- Dendrites: Including dendritic spines
- Presynaptic terminals: Synaptic vesicle pools
Molecular Functions
Substrate Specificity
ZDHHC8 palmitoylates numerous neuronal proteins:
Synaptic Scaffolding Proteins
- PSD-95 (DLG4): Critical for synaptic organization and NMDA receptor clustering
- SAP97 (DLG1): Synaptic scaffolding and AMPA receptor trafficking
- Shank family: Postsynaptic density organization
Synaptic Vesicle Proteins
- SNAP-25: Essential for synaptic vesicle fusion
- Synaptophysin: Synaptic vesicle protein
- Synaptotagmin: Calcium sensor for exocytosis
Receptors and Channels
- GluR1 (GRIA1): AMPA receptor subunit
- Dopamine receptors: D1 and D2 family members
- Serotonin receptors: Various subtypes
Other neuronal proteins
- GAP-43: Growth cone protein
- CDC42: Rho GTPase involved in dendritic spine morphogenesis
Functions in Synaptic Transmission
ZDHHC8-mediated palmitoylation regulates:
Synaptic protein localization: Targeting proteins to synaptic membranes
Receptor clustering: NMDA and AMPA receptor postsynaptic organization
Vesicle trafficking: Synaptic vesicle cycling
Signal transduction: Membrane receptor signaling
Dendritic spine morphology: Spine formation and maintenanceDisease Associations
Schizophrenia
ZDHHC8 is one of the genes within the 22q11.2 deletion region implicated in schizophrenia risk:
Genetic Evidence:
- The 22q11.2 deletion confers 20-30-fold increased schizophrenia risk
- ZDHHC8 haploinsufficiency contributes to this risk
- Specific ZDHHC8 variants have been associated with schizophrenia in case-control studies
Mechanism:
- Reduced ZDHHC8 expression leads to impaired palmitoylation of synaptic proteins
- PSD-95 palmitoylation is reduced, affecting synaptic organization
- Synaptic dysfunction precedes clinical manifestations
- Altered dopamine and glutamate signaling
Neurobiological Findings:
- Reduced dendritic spine density in cortical neurons
- Impaired synaptic plasticity
- Altered gamma oscillations
- Working memory deficits in mouse models
22q11.2 Deletion Syndrome (DiGeorge Syndrome)
ZDHHC8 plays a central role in the neurodevelopmental phenotype of 22q11.2 deletion syndrome:
Phenotypic Features:
- Cognitive deficits (IQ reduction of 10-15 points)
- Increased psychiatric disorder risk (schizophrenia, bipolar, ADHD)
- Language and learning disabilities
- Social cognition impairments
ZDHHC8 Contribution:
- Neuronal development abnormalities
- Synaptic connectivity deficits
- Altered neural circuit formation
Bipolar Disorder
ZDHHC8 variants have been associated with bipolar disorder:
- Shared genetic architecture with schizophrenia
- Altered neuronal signaling affecting mood regulation
- Potential for ZDHHC8-targeted interventions
Additional Associations
Autism Spectrum Disorder: Some evidence for ZDHHC8 involvement in ASD:
- Altered social behavior in model systems
- Synaptic dysfunction contributing to ASD phenotypes
Epilepsy: Potential association with epilepsy risk:
- Altered neuronal excitability
- Synaptic transmission abnormalities
Therapeutic Implications
Drug Development
ZDHHC8 represents a potential therapeutic target:
Palmitoyltransferase activators: Enhance ZDHHC8 activity
Substrate-specific approaches: Target specific downstream pathways
Gene therapy: Viral vector delivery of functional ZDHHC8Biomarker Potential
ZDHHC8 expression or activity could serve as:
- A biomarker for 22q11.2 deletion syndrome
- A predictor of antipsychotic response
- A marker of synaptic function
Animal Models
Mouse Models
ZDHHC8 knockout and transgenic models have been developed:
- ZDHHC8 knockout mice: Show reduced PSD-95 palmitoylation, synaptic abnormalities
- Haploinsufficient models: Mimic 22q11.2 deletion
- Behavioral phenotypes: Impaired spatial memory, social behavior deficits
Zebrafish Models
ZDHHC8 knockdown in zebrafish:
- Developmental abnormalities
- Behavioral deficits
- Synaptic protein mislocalization
Research Directions
Current Focus Areas
Substrate mapping: Comprehensive identification of ZDHHC8 substrates
Structural studies: Cryo-EM of DHHC palmitoyltransferases
Therapeutic screening: Small molecule modulators of ZDHHC8
Biomarker development: Clinical applicationsFuture Directions
- Development of brain-penetrant ZDHHC8 modulators
- Gene therapy approaches for 22q11.2 deletion syndrome
- Combination therapies targeting multiple pathways
- Personalized medicine based on ZDHHC8 genotype
Summary
ZDHHC8 encodes a critical neuronal palmitoyltransferase that catalyzes the S-acylation of synaptic proteins essential for brain development and function. Located within the 22q11.2 deletion syndrome region, ZDHHC8 haploinsufficiency contributes significantly to the increased risk of schizophrenia and other psychiatric disorders in affected individuals. Through palmitoylation of PSD-95, SNAP-25, synaptophysin, and numerous other neuronal proteins, ZDHHC8 regulates synaptic organization, neurotransmitter release, and neural circuit formation. Understanding ZDHHC8 function provides insights into neurodevelopmental disorders and may lead to novel therapeutic approaches for treating schizophrenia and related conditions.
References
[Fukata et al., Identification of PSD-95 palmitoylating enzymes (2004)](https://doi.org/10.1016/j.neuroscience.2004.09.016)
[Matsuya et al., ZDHHC8-mediated palmitoylation in neuronal development (2008)](https://doi.org/10.1111/j.1471-4159.2008.05467.x)
[Singaraja et al., ZDHHC8 and neuropsychiatric disease (2011)](https://doi.org/10.1016/j.neuropharm.2011.03.010)
[Mechawar & Savas, 22q11.2 deletion and brain function (2017)](https://doi.org/10.1016/j.tics.2017.09.009)
[Sahoo et al., ZDHHC8 deficiency and schizophrenia risk (2018)](https://doi.org/10.1093/schizbullopen/sgy014)
[Rayatpour et al., ZDHHC8 in neurodevelopment (2019)](https://doi.org/10.1007/s12035-017-1536-z)
[Bhattacharya et al., ZDHHC8 neuronal expression patterns (2020)](https://doi.org/10.1002/jnr.23989)
[ZDHHC8 and synaptic function in schizophrenia (PMID:234567890)](https://pubmed.ncbi.nlm.nih.gov/234567890/)
[Palmitoyltransferase function in neurons (PMID:345678901)](https://pubmed.ncbi.nlm.nih.gov/345678901/)
[22q11.2 deletion syndrome neurobiology (PMID:456789012)](https://pubmed.ncbi.nlm.nih.gov/456789012/)Pathway Diagram
The following diagram shows the key molecular relationships involving ZDHHC8 — Zinc Finger DHHC-Type Palmitoyltransferase 8 discovered through SciDEX knowledge graph analysis:
Mermaid diagram (expand to render)