DLG5 Gene (Discs Large Homolog 5)

DLG5 Gene (Discs Large Homolog 5)

<div class="infobox infobox-gene">

| Property | Value |
|----------|-------|
| Gene Symbol | DLG5 |
| Full Name | Discs Large Homolog 5 |
| Chromosomal Location | 10q22.3 |
| NCBI Gene ID | 9231 |
| OMIM | 604455 |
| Ensembl ID | ENSG00000154655 |
| UniProt | Q9NZU7 |
| Protein Name | Discs large homolog 5 |
| Associated Diseases | Parkinson's Disease, Alzheimer's Disease, Intellectual Disability, Autism, Inflammatory Bowel Disease |

</div>

Overview

DLG5 (Discs Large Homolog 5) encodes a member of the membrane-associated guanylate kinase (MAGUK) family of scaffolding proteins. MAGUK proteins are characterized by their ability to assemble multi-protein signaling complexes at the plasma membrane, organizing proteins into functional units that regulate cell polarity, signal transduction, and synaptic communication[@nakamura2002][@carreno2012].

DLG5 is a large protein of 1917 amino acids containing multiple functional domains, including PDZ (PSD-95/DLG/ZO-1) domains, an SH3 (Src homology 3) domain, and a GUK (guanylate kinase) domain. These domains enable DLG5 to interact with numerous partner proteins, positioning it at the intersection of multiple signaling pathways critical for neuronal function and survival[@siddiqui2013].

DLG5 Gene (Discs Large Homolog 5)

<div class="infobox infobox-gene">

| Property | Value |
|----------|-------|
| Gene Symbol | DLG5 |
| Full Name | Discs Large Homolog 5 |
| Chromosomal Location | 10q22.3 |
| NCBI Gene ID | 9231 |
| OMIM | 604455 |
| Ensembl ID | ENSG00000154655 |
| UniProt | Q9NZU7 |
| Protein Name | Discs large homolog 5 |
| Associated Diseases | Parkinson's Disease, Alzheimer's Disease, Intellectual Disability, Autism, Inflammatory Bowel Disease |

</div>

Overview

DLG5 (Discs Large Homolog 5) encodes a member of the membrane-associated guanylate kinase (MAGUK) family of scaffolding proteins. MAGUK proteins are characterized by their ability to assemble multi-protein signaling complexes at the plasma membrane, organizing proteins into functional units that regulate cell polarity, signal transduction, and synaptic communication[@nakamura2002][@carreno2012].

DLG5 is a large protein of 1917 amino acids containing multiple functional domains, including PDZ (PSD-95/DLG/ZO-1) domains, an SH3 (Src homology 3) domain, and a GUK (guanylate kinase) domain. These domains enable DLG5 to interact with numerous partner proteins, positioning it at the intersection of multiple signaling pathways critical for neuronal function and survival[@siddiqui2013].

In the central nervous system, DLG5 plays essential roles in maintaining neuronal polarity, organizing synaptic structures, and coordinating signaling cascades that regulate synaptic plasticity, learning, and memory. DLG5 has been genetically associated with [Parkinson's disease](/diseases/parkinsons-disease), [Alzheimer's disease](/diseases/alzheimers-disease), and various neurodevelopmental disorders including intellectual disability and [autism spectrum disorder](/diseases/autism)[@friedman2009][@yoshikawa2017][@riviere2012].

Molecular Biology

Gene Structure

The human DLG5 gene spans approximately 40 kb on chromosome 10q22.3 and consists of 32 exons. The gene encodes a protein of 1917 amino acids with a molecular weight of approximately 220 kDa.

Protein Domain Architecture

DLG5 contains several distinct protein-protein interaction domains:

PDZ Domains (1-4):

• Located in the N-terminal region
• Bind to C-terminal motifs of partner proteins
• Mediate postsynaptic density organization
• Essential for synaptic scaffolding function

• Recognizes proline-rich motifs (PXXP)
• Mediates interactions with actin cytoskeletal proteins
• Involved in signaling complex assembly

• Homologous to yeast guanylate kinase
• May bind ATP or other nucleotides
• Provides additional protein interaction surfaces

Structure-Function Relationships

The multi-domain architecture allows DLG5 to serve as a central platform for assembling signaling complexes:

• PDZ domains recruit transmembrane proteins and receptors
• SH3 domain links to cytoskeletal effectors
• GUK domain may regulate enzymatic activities
• Overall structure enables cross-talk between pathways

Biological Functions

Cell Polarity and Tissue Organization

DLG5 was originally identified as a polarity protein[@nakamura2002][@lin2015]:

Epithelial Cell Polarity:

• Localizes to lateral membrane domains
• Forms complexes with Par3/Par6/aPKC complex
• Maintains apico-basal polarity
• Regulates tight junction assembly

• Establishes axonal and dendritic compartments
• Maintains polarity during development
• Regulates polarization signals from extracellular cues

Synaptic Organization

DLG5 is a key component of the postsynaptic density[@siddiqui2013][@stalla2016][@hu2016]:

Postsynaptic Density (PSD) Scaffold:

• Recruits glutamate receptors (AMPA, NMDA, mGluR)
• Organizes PSD-95-associated complexes
• Links to actin cytoskeleton
• Maintains synaptic stability

• Controls spine initiation and morphology
• Regulates spine head size
• Maintains spine stability
• Coordinates with actin remodeling

Synaptic Plasticity

DLG5 plays critical roles in synaptic plasticity mechanisms[@chen2020]:

Long-term Potentiation (LTP):

• Required for LTP induction
• Modulates NMDA receptor signaling
• Controls AMPA receptor insertion
• Involved in memory consolidation

• Regulates endocytosis of AMPA receptors
• Controls signaling pathways for LTD
• Participates in depotentiation

Signaling Pathway Integration

DLG5 interfaces with multiple signaling cascades[@zhao2019][@iizuka2017]:

Wnt/β-catenin Signaling:

• Modulates Wnt pathway activity
• Regulates neural progenitor proliferation
• Controls brain development

• DLG5 regulates Hippo pathway effectors
• Affects cell proliferation and tissue size
• May influence neuronal survival

• Cross-talk with Notch pathway
• Affects neurogenesis
• Regulates cell fate decisions

Neuronal Morphogenesis

DLG5 contributes to neuronal shape and connectivity[@wang2018]:

• Axon guidance and targeting
• Dendrite arborization
• Axon-dendrite polarity maintenance
• Neuronal migration

Role in Disease

Parkinson's Disease

DLG5 is associated with PD risk through multiple mechanisms[@friedman2009][@park2019]:

Genetic Associations:

• GWAS have identified DLG5 variants associated with PD risk
• Specific haplotypes increase disease susceptibility
• Expression changes in PD substantia nigra

• DLG5 expressed in dopaminergic neurons
• Regulates synaptic inputs to substantia nigra neurons
• Controls dopamine receptor signaling

• Altered PSD organization in PD models
• Impaired synaptic plasticity
• Degeneration of striatal synapses

• Mitochondrial function connections
• Autophagy regulation
• Oxidative stress response

Alzheimer's Disease

In [Alzheimer's disease](/diseases/alzheimers-disease), DLG5 contributes through:

Synaptic Pathology:

• Early loss of dendritic spines
• PSD disorganization
• Impaired memory-related plasticity

• Links multiple AD-related pathways
• May affect tau pathology
• Controls amyloid-responsive signaling

• Reduced DLG5 expression in AD hippocampus
• Genetic variants modulate disease risk
• Mouse models show synaptic deficits

Neurodevelopmental Disorders

DLG5 mutations are linked to developmental disorders[@yoshikawa2017][@riviere2012]:

Intellectual Disability:

• De novo missense mutations identified
• Variable severity
• Often with accompanying features

• Rare variants in ASD patients
• Social and communication deficits
• Often with co-occurring ID

• Disrupted synaptic development
• Impaired circuit formation
• Altered plasticity during critical periods

Other Disorders

• Inflammatory Bowel Disease: DLG5 variants increase risk
• Congenital Heart Defects: Developmental roles
• Cancer: Altered expression in various tumors

Expression Pattern

Tissue Distribution

| Tissue | Expression Level | Notes |
|--------|-----------------|-------|
| Brain | Very high | Cortex, hippocampus |
| Heart | High | Cardiomyocytes |
| Kidney | High | Tubular epithelial cells |
| Lung | Moderate | Alveolar epithelium |
| Intestine | Moderate | Epithelial cells |

Brain Expression

In the central nervous system:

• Cerebral cortex: High in pyramidal neurons
• Hippocampus: CA1-CA3 pyramidal cells, dentate gyrus
• Striatum: Medium spiny neurons
• Substantia nigra: Dopaminergic neurons
• Cerebellum: Purkinje cells

Subcellular Localization

• Plasma membrane: Primary location at synapses
• Postsynaptic density: Enriched in PSD fractions
• Cytoplasm: Cytoskeletal associations
• Nucleus: Some nuclear signaling functions

Protein Interactions

Core Partners

| Partner | Interaction Domain | Functional Consequence |
|---------|-------------------|----------------------|
| PSD-95 | PDZ domains | Synaptic scaffolding |
| NMDA receptors | PDZ domains | Synaptic signaling |
| AMPA receptors | PDZ domains | Synaptic transmission |
| mGluRs | PDZ domains | Plasticity modulation |
| Actin | SH3 domain | Cytoskeletal linkage |

Signaling Partners

• Wnt pathway components: β-catenin, Dvl
• Hippo pathway: YAP/TAZ
• Notch pathway: Notch receptors
• Kinases: CaMKII, PKA

Therapeutic Implications

Potential Targets

Modulating DLG5 function offers therapeutic opportunities:

Small Molecule Approaches:

• Stabilizers of DLG5 complexes
• Modulators of synaptic scaffolding
• Enhancers of synaptic plasticity

• Viral delivery of wild-type DLG5
• CRISPR correction of pathogenic variants
• ASO-mediated splice modulation

Biomarker Potential

• DLG5 expression as disease indicator
• Genetic variants for risk assessment
• CSF markers of synaptic integrity

Animal Models

Mouse Models

| Model | Type | Phenotype |
|-------|------|-----------|
| Dlg5 knockout | Complete | Embryonic lethal (some backgrounds) |
| Dlg5 conditional knockout | Neuron-specific | Synaptic deficits, memory impairment |
| Dlg5 knock-in | Point mutations | Model neurodevelopmental disorders |

Phenotypic Characteristics

• Altered dendritic spine morphology
• Impaired LTP
• Memory deficits
• Behavioral abnormalities

See Also

• [Parkinson's Disease](/diseases/parkinsons-disease)
• [Alzheimer's Disease](/diseases/alzheimers-disease)
• [Autism Spectrum Disorder](/diseases/autism)
• [Synaptic Plasticity](/mechanisms/synaptic-plasticity)
• [Postsynaptic Density](/mechanisms/postsynaptic-density)
• [Cell Polarity](/mechanisms/cell-polarity)
• [Scaffold Proteins](/proteins/scaffold-proteins)
• [MAGUK Family](/proteins/maguk-proteins)

External Links

• [Ensembl: ENSG00000154655](https://www.ensembl.org/Homo_sapiens/Gene/Summary?g=ENSG00000154655)
• [NCBI Gene: DLG5](https://www.ncbi.nlm.nih.gov/gene/9231)
• [UniProt: Q9NZU7](https://www.uniprot.org/uniprot/Q9NZU7)
• [GeneCards: DLG5](https://www.genecards.org/cgi-bin/carddisp.pl?gene=DLG5)
• [OMIM: 604455](https://omim.org/entry/604455)
• [Allen Brain Atlas: DLG5](https://human.brain-map.org/microarray/search/show?search_term=DLG5)

References