ZDHHC8 — Zinc Finger DHHC-Type Palmitoyltransferase 8

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ZDHHC8 — Zinc Finger DHHC-Type Palmitoyltransferase 8

<table class="infobox infobox-gene">
<tr>
<th class="infobox-header" colspan="2">ZDHHC8 — Zinc Finger DHHC-Type Palmitoyltransferase 8</th>
</tr>
<tr>
<td class="label">Symbol</td>
<td><strong>ZDHHC8</strong></td>
</tr>
<tr>
<td class="label">Full Name</td>
<td>Zinc Finger DHHC-Type Palmitoyltransferase 8</td>
</tr>
<tr>
<td class="label">Chromosome</td>
<td>22q11.21</td>
</tr>
<tr>
<td class="label">NCBI Gene</td>
<td><a href="https://www.ncbi.nlm.nih.gov/gene/57103" target="_blank">57103</a></td>
</tr>
<tr>
<td class="label">Ensembl</td>
<td><a href="https://ensembl.org/Homo_sapiens/Gene/Summary?g=ENSG00000140995" target="_blank">ENSG00000140995</a></td>
</tr>
<tr>
<td class="label">OMIM</td>
<td><a href="https://omim.org/entry/611415" target="_blank">611415</a></td>
</tr>
<tr>
<td class="label">UniProt</td>
<td><a href="https://www.uniprot.org/uniprot/Q9NXK5" target="_blank">Q9NXK5</a></td>
</tr>
<tr>
<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>
</tr>
<tr>
<td class="label">Expression</td>
<td>Brain (Cortex, Hippocampus, Cerebellum), Neurons</td>
</tr>
<tr>
<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>

...

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 Golgi

Catalytic 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 released

This 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 maintenance

Disease 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 ZDHHC8

Biomarker 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 applications

Future 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)

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