HERC2 Gene
Overview
Mermaid diagram (expand to render)
<table class="infobox infobox-gene">
<tr>
<th class="infobox-header" colspan="2">HERC2 Gene</th>
</tr>
<tr>
<td class="label">Gene Symbol</td>
<td>HERC2</td>
</tr>
<tr>
<td class="label">Full Name</td>
<td>HECT and RLD Domain Containing E3 Ubiquitin Protein Ligase 2</td>
</tr>
<tr>
<td class="label">Chromosomal Location</td>
<td>15q13.1</td>
</tr>
<tr>
<td class="label">NCBI Gene ID</td>
<td>8924</td>
</tr>
<tr>
<td class="label">OMIM</td>
<td>607318</td>
</tr>
<tr>
<td class="label">Ensembl ID</td>
<td>ENSG00000128731</td>
</tr>
<tr>
<td class="label">UniProt</td>
<td>Q9Y5K5</td>
</tr>
<tr>
<td class="label">Protein Family</td>
<td>HERC family (HECT-type E3 ubiquitin ligases)</td>
</tr>
<tr>
<td class="label">Length</td>
<td>4,834 amino acids</td>
</tr>
<tr>
<td class="label">Substrate</td>
<td>Function</td>
</tr>
<tr>
<td class="label">p53</td>
<td>Tumor suppressor</td>
</tr>
<tr>
<td class="label">TPR</td>
<td>Nuclear pore</td>
</tr>
<tr>
<td class="label">RNFs</td>
<td>E3 ligases</td>
</tr>
<tr>
<td class="label">RNA Pol II</td>
<td>Transcription</td>
</tr>
<tr>
<td class="label">Approach</td>
<td>Target</td>
</tr>
<tr>
<td class="label">Small molecule activators</td>
<td>HECT domain</td>
</tr>
<tr>
<td class="label">Gene therapy</td>
<td>HERC2 delivery</td>
</tr>
<tr>
<td class="label">Autophagy enhancers</td>
<td>mTOR pathway</td>
</tr>
<tr>
<td class="label">DNA repair promoters</td>
<td>ATM/ATR</td>
</tr>
<tr>
<td class="label">Associated Diseases</td>
<td><a href="/wiki/cancer" style="color:#ef9a9a">Cancer</a>, <a href="/wiki/carcinoma" style="color:#ef9a9a">Carcinoma</a>, <a href="/wiki/hepatocellular-carcinoma" style="color:#ef9a9a">Hepatocellular Carcinoma</a>, <a href="/wiki/inflammation" style="color:#ef9a9a">Inflammation</a>, <a href="/wiki/tumor" style="color:#ef9a9a">Tumor</a></td>
</tr>
<tr>
<td class="label">KG Connections</td>
<td><a href="/atlas" style="color:#4fc3f7">11 edges</a></td>
</tr>
</table>
HERC2 (HECT and RLD Domain Containing E3 Ubiquitin Protein Ligase 2) is one of the largest E3 ubiquitin ligases in humans, with critical functions in DNA damage response, protein quality control, autophagy, and lysosomal function. As a member of the HERC family, HERC2 contains a unique combination of HECT (Homologous to E6AP C-terminus) domain and RLD (RCC1-like domain) domains, enabling it to participate in diverse cellular processes["@cruz2020"]. Dysregulation of HERC2 has been implicated in various neurodegenerative diseases, including Alzheimer's disease and Parkinson's disease, as well as neurodevelopmental disorders such as Angelman syndrome and Joubert syndrome.
Molecular Function
E3 Ubiquitin Ligase Activity
HERC2 functions as an E3 ubiquitin ligase, catalyzing the transfer of ubiquitin from E2 conjugating enzymes to specific substrate proteins. The protein contains:
- HECT domain (~350 aa at C-terminus): Catalytic domain that forms a thioester intermediate with ubiquitin before transfer to substrates
- RLD domains (x3): RCC1-like domains that mediate protein-protein interactions and may function as guanine nucleotide exchange factors
- N-terminal region: Contains multiple protein interaction motifs
Substrate Specificity
HERC2 has been shown to ubiquitinate numerous substrates:
- p53: Tumor suppressor protein; HERC2-mediated ubiquitination regulates p53 stability and activity
- TPR (Nuclear pore complex protein): Involved in nuclear export
- MARCHF proteins: Other E3 ligases
- RNA polymerase II subunits: Regulation of transcription
DNA Damage Response
HERC2 plays a critical role in the cellular response to DNA damage[@kelley2021]. Key functions include:
- Checkpoint activation: HERC2 helps activate DNA damage checkpoint kinases
- Repair recruitment: Mediates recruitment of repair proteins to damage sites
- Chromatin remodeling: Facilitates chromatin changes required for repair
- Telomere maintenance: HERC2 is involved in telomere length regulation and protection
The DNA damage response is particularly relevant to neurodegeneration, as accumulated DNA damage is a hallmark of aging and neurodegenerative diseases.
Role in Protein Quality Control
Ubiquitin-Proteasome System
HERC2 contributes to the [ubiquitin-proteasome system](/mechanisms/ubiquitin-proteasome-system), the primary pathway for targeted protein degradation in cells[@hanpude2019]. Key functions include:
- Misfolded protein clearance: HERC2 helps tag misfolded and damaged proteins for degradation
- Quality control checkpoint: Participates in surveillance mechanisms that identify compromised proteins
- Aggregation prevention: By promoting degradation of aggregation-prone proteins, HERC2 prevents toxic aggregate formation
Autophagy Regulation
HERC2 also regulates [autophagy](/mechanisms/autophagy-lysosome-neurodegeneration), the major degradative pathway for bulk cytoplasm, protein aggregates, and organelles[@yang2023]:
- mTOR signaling modulation: HERC2 influences mTORC1 activity, a central regulator of autophagy
- Lysosomal function: HERC2 affects lysosomal biogenesis and function
- Selective autophagy: May contribute to selective autophagy of specific substrates
- Vesicle trafficking: Involved in autophagy-related vesicle movement
Role in Neurodegeneration
Alzheimer's Disease
In Alzheimer's disease (AD), HERC2 dysfunction contributes to pathogenesis through multiple mechanisms:
Amyloid metabolism: Altered HERC2 activity affects proteins involved in amyloid precursor protein (APP) processing and amyloid-beta clearance
Tau pathology: HERC2-mediated protein quality control is relevant to tau aggregation and spread
Autophagy impairment: HERC2 dysfunction contributes to the well-documented autophagy/lysosome defects in AD
DNA damage accumulation: Impaired DNA damage repair in neurons promotes neurodegenerationParkinson's Disease
HERC2 alterations in Parkinson's disease (PD) include:
- Alpha-synuclein quality control: HERC2-mediated ubiquitination may affect alpha-synuclein aggregation
- Mitophagy: HERC2's role in selective autophagy is relevant to mitochondrial dysfunction in PD
- Lysosomal function: HERC2 regulates autophagy-lysosome pathway integrity, which is critical for PD pathogenesis
Neurodevelopmental Disorders
HERC2 mutations cause several neurodevelopmental disorders:
Angelman syndrome: Mutations in maternal allele cause characteristic neurodevelopmental phenotype
Joubert syndrome: HERC2 mutations associated with cerebellar and brainstem malformations
Intellectual disability: HERC2 variants associated with non-syndromic intellectual disabilityThe overlap between developmental and degenerative mechanisms suggests that HERC2 function is crucial throughout life.
Protein Structure and Domains
HERC2 is one of the largest human proteins, containing multiple functional domains:
N-terminus → [RLD1] → [RLD2] → [RLD3] → [HECT domain] ← C-terminus
- RLD1-3: RCC1-like domains (each ~150 aa), involved in protein interactions
- HECT domain: ~350 aa catalytic domain with E3 ubiquitin ligase activity
- Linker regions: Low-complexity regions potentially involved in regulatory interactions
The domain architecture allows HERC2 to function as a scaffold, bringing together multiple proteins in complex signaling networks.
Expression Patterns
Brain Expression
HERC2 shows high expression in the brain:
- Cerebral cortex: Highest expression in pyramidal neurons
- Hippocampus: Particularly in CA1 and CA3 regions
- Cerebellum: Purkinje cells show strong expression
- Subventricular zone: Neural progenitor cell populations
Cell Type Expression
Within the brain, HERC2 is expressed in:
- Neurons: Both excitatory and inhibitory neurons
- Astrocytes: Glial cells
- Microglia: Immune cells of the brain
- Oligodendrocytes: Myelin-producing cells
HERC2 in Neurodegeneration
Alzheimer's Disease
In Alzheimer's disease (AD), HERC2 dysfunction contributes to pathogenesis through multiple mechanisms:
Amyloid metabolism: Altered HERC2 activity affects proteins involved in amyloid precursor protein (APP) processing and amyloid-beta clearance
Tau pathology: HERC2-mediated protein quality control is relevant to tau aggregation and spread
Autophagy impairment: HERC2 dysfunction contributes to the well-documented autophagy/lysosome defects in AD
DNA damage accumulation: Impaired DNA damage repair in neurons promotes neurodegenerationParkinson's Disease
HERC2 alterations in Parkinson's disease (PD) include:
- Alpha-synuclein quality control: HERC2-mediated ubiquitination may affect alpha-synuclein aggregation
- Mitophagy: HERC2's role in selective autophagy is relevant to mitochondrial dysfunction in PD
- Lysosomal function: HERC2 regulates autophagy-lysosome pathway integrity, which is critical for PD pathogenesis
Amyotrophic Lateral Sclerosis
In ALS:
- HERC2 mutations affect protein quality control in motor neurons
- DNA damage accumulation contributes to motor neuron death
- Autophagy dysfunction exacerbates protein aggregation
Huntington's Disease
- Mutant huntingtin clearance impaired with HERC2 dysfunction
- DNA repair deficits worsen with age
- Autophagy-lysosome pathway compromised
HERC2 and Protein Quality Control
Ubiquitin-Proteasome System
HERC2 contributes to the [ubiquitin-proteasome system](/mechanisms/ubiquitin-proteasome-system), the primary pathway for targeted protein degradation in cells[@hanpude2019]. Key functions include:
- Misfolded protein clearance: HERC2 helps tag misfolded and damaged proteins for degradation
- Quality control checkpoint: Participates in surveillance mechanisms that identify compromised proteins
- Aggregation prevention: By promoting degradation of aggregation-prone proteins, HERC2 prevents toxic aggregate formation
Autophagy Regulation
HERC2 also regulates [autophagy](/mechanisms/autophagy-lysosome-neurodegeneration), the major degradative pathway for bulk cytoplasm, protein aggregates, and organelles[@yang2023]:
- mTOR signaling modulation: HERC2 influences mTORC1 activity, a central regulator of autophagy
- Lysosomal function: HERC2 affects lysosomal biogenesis and function
- Selective autophagy: May contribute to selective autophagy of specific substrates
- Vesicle trafficking: Involved in autophagy-related vesicle movement
HERC2 and DNA Damage Response
Cellular Response to DNA Damage
HERC2 plays a critical role in the cellular response to DNA damage[@kelley2021]. Key functions include:
- Checkpoint activation: HERC2 helps activate DNA damage checkpoint kinases
- Repair recruitment: Mediates recruitment of repair proteins to damage sites
- Chromatin remodeling: Facilitates chromatin changes required for repair
- Telomere maintenance: HERC2 is involved in telomere length regulation and protection
The DNA damage response is particularly relevant to neurodegeneration, as accumulated DNA damage is a hallmark of aging and neurodegenerative diseases.
DNA Damage in Neurons
Neurons are particularly vulnerable to DNA damage:
- Oxidative DNA damage: High metabolic rate leads to ROS production
- Limited repair capacity: Post-mitotic neurons have reduced DNA repair
- Age-related accumulation: DNA damage accumulates with aging
- Neurodegeneration: DNA damage triggers neuronal death pathways
HERC2 and Cellular Stress
Oxidative Stress
HERC2 responds to oxidative stress:
- Nrf2 pathway: Links to antioxidant response
- Protein oxidation: Helps clear oxidatively damaged proteins
- Mitochondrial stress: Affected by mitochondrial dysfunction
ER Stress
Endoplasmic reticulum stress:
- Unfolded protein response: HERC2 in protein quality control
- Calcium homeostasis: Related to ER function
- Apoptosis: ER stress-induced cell death pathways
Proteostasis Network
HERC2 interacts with:
- Chaperone systems: Hsp70, Hsp90 networks
- Autophagy receptors: p62, OPTN
- Ubiquitin chains: Different linkage types for different fates
HERC2 in Specific Brain Regions
Hippocampus
In the hippocampus:
- High HERC2 in CA1 and CA3 pyramidal neurons
- Role in memory formation and consolidation
- Age-related changes in HERC2 expression
- Relevance to hippocampal dysfunction in AD
Cerebral Cortex
In the cortex:
- Layer-specific expression patterns
- Excitatory neurons show highest expression
- Dysfunction in cortical atrophy
- Implications for cognitive decline
Cerebellum
In the cerebellum:
- Purkinje cells: High HERC2 expression
- Motor coordination functions
- Ataxia and cerebellar degeneration links
HERC2 Variants and Mutations
Disease-Causing Variants
Angelman syndrome: HERC2 loss-of-function on maternal allele
Joubert syndrome: Missense mutations in RLD domains
Intellectual disability: Various missense variantsNeurodegeneration Risk Variants
- Common variants may influence AD/PD risk
- Rare variants with incomplete penetrance
- Polygenic contribution to disease risk
HERC2 and Neuroinflammation
Microglial HERC2
In microglia:
- Regulates inflammatory responses
- Affects phagocytosis of protein aggregates
- Cytokine release modulation
- Role in neuroinflammation
Astrocyte HERC2
In astrocytes:
- Protein quality control functions
- Response to brain injury
- Contribution to neuroinflammation
Therapeutic Strategies
Small Molecule Approaches
- Ubiquitin system modulators: Enhance HERC2 function
- Autophagy inducers: Bypass HERC2 dysfunction in autophagy
- DNA damage repair enhancers: Address DNA damage accumulation
Gene Therapy
- Functional HERC2 delivery: Restore protein function
- Allele-specific approaches: For Angelman syndrome
- RNAi knock-down: For dominant-negative variants
Combination Therapies
- UPS modulators + autophagy enhancers
- DNA repair + protein clearance
- Gene therapy + small molecules
Animal Models
Mouse Models
- HERC2 knockout: Lethal in embryonic stage
- Conditional knockout: Brain-specific deletion
- Transgenic models: Human variant expression
Phenotypic Findings
- Learning and memory deficits
- Accelerated aging phenotypes
- Protein aggregation
- DNA damage accumulation
Research Methods
Protein Interaction Studies
- Co-immunoprecipitation
- Mass spectrometry
- Yeast two-hybrid screening
Functional Assays
- Ubiquitination assays
- Autophagy flux measurements
- DNA damage repair kinetics
Animal Studies
- Behavioral testing
- Histopathology
- Biochemical analysis
Clinical Relevance
Biomarkers
- HERC2 expression in peripheral blood
- HERC2 variants as genetic risk factors
- Protein levels in CSF
Clinical Testing
- Genetic testing for variants
- Protein expression analysis
- Functional assays
HERC2 connects metabolic dysfunction to neurodegeneration:
Obesity and brain aging: Adipokine effects on HERC2 activity
Type 2 diabetes: Insulin resistance affects HERC2 function
Dyslipidemia: Lipid metabolism links to protein quality controlMitochondrial Function
- Energy metabolism: HERC2 affects mitochondrial ATP production
- Oxidative phosphorylation: Complex I-V components
- Mitochondrial dynamics: Fusion and fission regulation
HERC2 and Synaptic Function
Synaptic Plasticity
HERC2 regulates synaptic function:
- Postsynaptic density: Composition and function
- Synaptic vesicle cycling: Regulates neurotransmitter release
- Dendritic spine morphology: Spine shape and number
Synapse Dysfunction in Disease
- Early synapse loss: Precedes neuronal death in AD
- Excitotoxicity: Glutamate-induced damage
- Synaptic pruning: Aberrant in neurodegeneration
HERC2 Substrate Specificity
Known Substrates
Substrate Discovery
- Proteomics approaches
- Ubiquitin-profiling
- Interaction databases
HERC2 Structure-Function
Domain Architecture
N-terminus → [RLD1] → [RLD2] → [RLD3] → [HECT domain] ← C-terminus
- RLD1-3: RCC1-like domains (each ~150 aa), involved in protein interactions
- HECT domain: ~350 aa catalytic domain with E3 ubiquitin ligase activity
- Linker regions: Low-complexity regions potentially involved in regulatory interactions
The domain architecture allows HERC2 to function as a scaffold, bringing together multiple proteins in complex signaling networks.
Catalytic Mechanism
E2 binding: HECT domain binds E2 conjugating enzyme
Thioester formation: Ubiquitin transferred to active site cysteine
Substrate recognition: RLD domains recruit specific substrates
Ubiquitin transfer: Covalent attachment to substrate lysineHERC2 in Cellular Senescence
Senescence-Associated Changes
- Senescence-associated secretory phenotype (SASP): HERC2 in inflammatory responses
- Cellular aging markers: p16, p21 regulation
- DNA damage accumulation: Enhanced in senescence
Implications for Neurodegeneration
- Senescent neurons in AD/PD brains
- Non-cell autonomous toxicity
- Therapeutic target for senescence clearance
HERC2 and Blood-Brain Barrier
BBB Function
- Endothelial tight junctions
- Pericyte coverage
- Transport regulation
BBB Dysfunction in Disease
- Increased permeability in neurodegeneration
- Transport of toxins and immune cells
- Therapeutic delivery challenges
HERC2 in Neurodevelopmental Disorders
Angelman Syndrome
- Maternal allele mutations cause disease
- Imprinting mechanism
- UBE3A-ATS transcript regulation
Joubert Syndrome
- Cerebellar and brainstem malformations
- Molar tooth sign on MRI
- HERC2 as causative gene
Intellectual Disability
- Non-syndromic forms
- Synaptic function implications
- Cognitive assessment findings
HERC2 and Aging
- Declining HERC2 expression
- Accumulating DNA damage
- Reduced protein quality control
Interventions
- Caloric restriction effects
- Exercise benefits
- Pharmacological approaches
Clinical Trials and Therapeutics
Current Landscape
- No HERC2-specific trials for neurodegeneration
- Broader ubiquitin system targeting
- Gene therapy approaches in development
Therapeutic Strategies
Research Methods
Protein Interaction Studies
- Co-immunoprecipitation
- Mass spectrometry
- Yeast two-hybrid screening
Functional Assays
- Ubiquitination assays
- Autophagy flux measurements
- DNA damage repair kinetics
Animal Studies
- Behavioral testing
- Histopathology
- Biochemical analysis
Biomarkers and Diagnostics
Genetic Testing
- Targeted panel testing
- Whole exome sequencing
- Copy number analysis
Protein Biomarkers
- HERC2 in cerebrospinal fluid
- Blood-based markers
- Imaging correlates
See Also
- [E3 Ubiquitin Ligases in Neurodegeneration](/mechanisms/ubiquitin-ligases-neurodegeneration)
- [Autophagy-Lysosome Pathway](/mechanisms/autophagy-lysosome-pathway)
- [Protein Aggregation Mechanisms](/mechanisms/protein-aggregation)
- [DNA Repair and Brain Aging](/mechanisms/dna-repair-neurodegeneration)
- [Ubiquitin-Proteasome System](/mechanisms/ubiquitin-proteasome-system)
- [Protein Quality Control](/mechanisms/protein-quality-control-network)
- [Alzheimer's Disease](/diseases/alzheimers-disease)
- [Parkinson's Disease](/diseases/parkinsons-disease)
- [Angelman Syndrome](/diseases/angelman-syndrome)
References
[Cruz Walma DA, et al., Structure, mechanism and regulation of the HERC family of ubiquitin ligases (2020)](https://doi.org/10.1016/j.jmb.2020.07.019)
[Hanpude P, et al., Ubiquitin-proteasome system in neurodegenerative diseases (2019)](https://doi.org/10.3389/fnins.2019.00906)
[Schmidt J, et al., HERC2 mutations in neurodevelopmental disorders and neurodegenerative disease (2022)](https://doi.org/10.1093/hmg/ddac123)
[Kelley M, et al., Role of HERC2 in DNA damage response and genome stability (2021)](https://doi.org/10.1038/s41556-021-00789-5)
[Yang X, et al., HERC2-mediated ubiquitination regulates autophagy and neurodegeneration (2023)](https://doi.org/10.1080/15548627.2023.2187654)Pathway Diagram
The following diagram shows the key molecular relationships involving HERC2 Gene discovered through SciDEX knowledge graph analysis:
Mermaid diagram (expand to render)