HERC2 is a giant E3 ubiquitin ligase (~500 kDa) involved in protein ubiquitination, DNA repair, and cellular stress responses. It plays critical roles in genome stability and has been implicated in neurodegenerative diseases including Alzheimer's disease and Parkinson's disease.
HERC2 contains multiple functional domains:
- HECT domain (~350 aa at C-terminus): Catalytic E3 ubiquitin ligase activity
- RING finger domain: E3 ligase activity for substrate recognition
- WD40 repeats: Protein-protein interactions
- HECT-like domain: Regulatory functions
- Multiple RCC1 repeats: Chromatin binding
The protein is one of the largest E3 ligases known, with over 4,800 amino acids.
HERC2 functions as an E3 ubiquitin ligase:
- Targets proteins for proteasomal degradation
- Catalyzes ubiquitin chain formation
- Regulates protein turnover
- Controls cellular protein homeostasis
- Regulates p53 activity through MDM2
- DNA damage response coordination
- Cell cycle control
- Genome stability maintenance
- Regulates iron homeostasis
- Affects transferrin receptor trafficking
- Links ubiquitination to iron metabolism
- Important for neuronal survival
- Regulates autophagy initiation
- Controls selective autophagy receptors
- Degrades damaged organelles
- Maintains cellular quality control
- Amyloid processing: HERC2 affects APP trafficking and processing
- Tau ubiquitination: May regulate tau degradation
- Oxidative stress: Links to cellular stress responses
- Autophagy: Dysregulation of lysosomal pathways
- Altered expression in AD brain
- Interactions with AD-related proteins
- Potential role in amyloid clearance
- Mitochondrial quality control
- PINK1/Parkin pathway: HERC2 may interact with mitophagy
- Alpha-synuclein: Potential clearance mechanisms
- Mitochondrial dysfunction: Iron metabolism links
- LRRK2 interactions: Possible pathway connections
- Huntington's disease: Polyglutamine aggregate clearance
- Amyotrophic lateral sclerosis: Protein homeostasis
- Frontotemporal dementia: Ubiquitin pathology
- Targets misfolded proteins
- Regulates stress response proteins
- Controls transcription factors
- Maintains neuronal health
- Modulates mTOR pathway
- Controls ULK1 complex
- Regulates selective autophagy
- Links to neurodegeneration
- NF-κB pathway regulation
- p53-dependent apoptosis
- MAPK/ERK signaling
- DNA damage responses
- HERC2 modulators (in development)
- Proteostasis enhancers
- Autophagy-inducing compounds
- Mitochondrial protectants
- HERC2 expression as disease marker
- Activity in cerebrospinal fluid
- Genetic variants as risk factors
- HERC2 variants associated with AD risk
- Expression quantitative trait loci (eQTLs) in brain
- Epigenetic regulation in disease
- Knockout mice: Lethal in embryonic stage
- Conditional knockouts: Neurodegeneration phenotype
- Cell models: Oxidative stress sensitivity