Ube2N is an important component in the neurobiology of neurodegenerative diseases. This page provides detailed information about its structure, function, and role in disease processes.
| UBE2N Gene |
|---|
| Gene Symbol | UBE2N |
| Full Name | Ubiquitin-Conjugating Enzyme E2 N |
| Chromosomal Location | 19q13.43 |
| NCBI Gene ID | [7334](https://www.ncbi.nlm.nih.gov/gene/7334) |
| OMIM ID | 607252 |
| Ensembl ID | [ENSG00000108987](https://www.ensembl.org/Homo_sapiens/ENSG00000108987) |
| UniProt ID | [P61079](https://www.uniprot.org/uniprot/P61079) |
| Protein Name | Ubiquitin-conjugating enzyme E2 N |
| Aliases | Ubc13, UEV1A, E2-25K |
| Associated Diseases | Alzheimer's Disease, Parkinson's Disease, Neuroinflammation, Amyotrophic Lateral Sclerosis |
UBE2N (Ubiquitin-Conjugating Enzyme E2 N), also known as Ubc13 or UEV1A, encodes a key enzyme in the ubiquitin-proteasome system (UPS) that catalyzes the formation of Lys63-linked polyubiquitin chains. Unlike Lys48-linked ubiquitination which targets proteins for proteasomal degradation, Lys63-linked polyubiquitination primarily serves non-degradative signaling functions including NF-κB activation, DNA damage repair, immune signaling, and endosomal trafficking.
UBE2N forms a heterodimer with UEV1A (UBE2V1) or MMS2 (UBE2V2) to catalyze Lys63-linked polyubiquitination:
- Initiation: UBE2N~Ub thioester forms via ATP-dependent charging
- Chain elongation: The UBE2N-UBE2V heterodimer transfers ubiquitin to the Lys63 residue of a substrate-bound ubiquitin
- Signal generation: Lys63-polyubiquitin chains serve as signaling platforms for downstream effectors
- NF-κB Signaling: Lys63-polyubiquitin chains on TRAF6, NEMO, and other signaling intermediates activate NF-κB transcription factors
- DNA Damage Repair: UBE2N-mediated ubiquitination promotes recruitment of repair factors to DNA double-strand breaks
- Endosomal Trafficking: Ubiquitination of membrane proteins regulates sorting into multivesicular bodies
- Synaptic Function: UBE2N is enriched in synapses and regulates postsynaptic signaling
UBE2N is ubiquitously expressed with high levels in:
- Brain (cortex, hippocampus, basal ganglia)
- Immune cells (T cells, B cells, macrophages)
- Peripheral tissues (liver, kidney)
In Alzheimer's disease, UBE2N dysfunction contributes to:
- Tau Pathology: Altered UBE2N activity affects tau ubiquitination and aggregation
- Amyloid-β Signaling: Lys63-ubiquitination modulates APP processing and Aβ toxicity
- Synaptic Loss: Impaired synaptic ubiquitin signaling contributes to dendritic spine degeneration
- Neuroinflammation: NF-κB hyperactivation via UBE2N promotes chronic neuroinflammation
UBE2N plays complex roles in PD:
- α-Synuclein Turnover: The enzyme regulates autophagy and lysosomal degradation of α-synuclein aggregates
- Mitochondrial Quality Control: UBE2N-mediated ubiquitination participates in mitophagy
- LRRK2 Signaling: UBE2N interacts with LRRK2 kinase pathway
- Dopaminergic Vulnerability: Altered ubiquitination may contribute to selective dopaminergic neuron loss
- Protein Aggregation: UBE2N dysfunction may contribute to TDP-43 and SOD1 aggregate formation
- RNA Metabolism: Interactions with RNA-binding proteins affected in ALS
- Axonal Transport: Ubiquitin signaling deficits impair axonal homeostasis
UBE2N is a critical regulator of neuroinflammation through:
- Microglial Activation: NF-κB pathway activation in microglia
- Cytokine Production: Regulation of IL-1β, TNF-α, and IL-6 expression
- T Cell Polarization: Antigen presentation and adaptive immunity
UBE2N represents a therapeutic target for neurodegeneration:
- Modulating NF-κB: Selective inhibitors could reduce neuroinflammation
- Enhancing Protein Clearance: Activators might promote aggregate clearance
- Synaptic Protection: UBE2N activators could protect synapses
- No UBE2N-targeted drugs are currently in clinical trials for neurodegeneration
- Preclinical studies of NF-κB modulators show promise in AD/PD models
- Gene therapy approaches to enhance UPS function are under investigation
¶ Diagnostic and Biomarker Potential
- Research Use: UBE2N expression levels studied as potential biomarker
- Genetic Variants: Some UBE2N SNPs associated with AD risk
- Therapeutic Monitoring: Could serve as pharmacodynamic marker
- Knockout Mice: UBE2N knockout is embryonic lethal; conditional knockouts used
- Transgenic Models: Overexpression models show NF-κB dysregulation
- Phenotypes: Defects in immune function, DNA repair, and synaptic plasticity
¶ Interactions and Pathways
- UBE2V1/V2: Heterodimer formation for chain synthesis
- TRAF6: Downstream NF-κB activator
- NEMO: NF-κB essential modifier
- TRAF2: TNF receptor-associated factor
- RIP1: Receptor-interacting protein kinase 1
TNF-α/NF-κB Pathway:
TNF-α → TNFR1 → TRAF2/6 → UBE2N-mediated ubiquitination → NEMO → IKK → IκB degradation → NF-κB nuclear translocation → Gene transcription
DNA Damage Pathway:
DNA damage → ATM/ATR → RNF8/RNF168 → UBE2N ubiquitination → BRCA1 recruitment → DNA repair
- Complexity: UBE2N has both protective and pathogenic roles
- Selectivity: Developing selective modulators is challenging
- Blood-Brain Barrier: Therapeutic delivery to CNS
- Biomarkers: Need for patient stratification markers
The study of Ube2N has evolved significantly over the past decades. Research in this area has revealed important insights into the underlying mechanisms of neurodegeneration and continues to drive therapeutic development.
Historical context and key discoveries in this field have shaped our current understanding and will continue to guide future research directions.