ITCH (Itchy Homolog, E3 Ubiquitin Protein Ligase) is a HECT-type E3 ubiquitin ligase belonging to the NEDD4 family. It plays critical roles in protein quality control, signal transduction, and immune regulation. ITCH-mediated ubiquitination targets proteins for degradation via the [ubiquitin-proteasome system](/mechanisms/ubiquitin-proteasome-system) and regulates various cellular processes relevant to neurodegeneration[@galligan2022].
ITCH (Itchy Homolog, E3 Ubiquitin Protein Ligase) is a HECT-type E3 ubiquitin ligase belonging to the NEDD4 family. It plays critical roles in protein quality control, signal transduction, and immune regulation. ITCH-mediated ubiquitination targets proteins for degradation via the [ubiquitin-proteasome system](/mechanisms/ubiquitin-proteasome-system) and regulates various cellular processes relevant to neurodegeneration[@galligan2022].
Structure
ITCH contains an N-terminal C2 domain for calcium-dependent membrane localization, multiple WW domains for protein-protein interactions, and a C-terminal HECT domain that catalyzes ubiquitin transfer. The WW domains recognize PY motifs (PPxY) in substrate proteins, enabling substrate specificity[@rotin2021].
Synaptic plasticity: Controls AMPA receptor trafficking and synaptic strength
Protein quality control: Targets misfolded proteins for degradation
Signal transduction: Modulates MAPK/ERK and PI3K/Akt pathways
Inflammatory responses: Regulates [NF-κB](/entities/nf-kb) signaling in [microglia](/cell-types/microglia-neuroinflammation)
[Autophagy](/entities/autophagy): Participates in selective autophagy receptor degradation
ITCH functions as a molecular scaffold assembling signaling complexes and as an E3 ligase mediating substrate ubiquitination[@chen2023].
Role in Neurodegeneration
Alzheimer's Disease
ITCH dysfunction contributes to AD pathogenesis through multiple mechanisms:
[Aβ](/proteins/amyloid-beta) metabolism: ITCH regulates [APP](/entities/app-protein) processing and Aβ generation via ubiquitination of [BACE1](/entities/bace1) and ADAM10[@zhang2021]
[Tau](/proteins/tau) pathology: ITCH-mediated degradation of tau kinases (GSK-3β) may influence tau phosphorylation
Synaptic dysfunction: Loss of ITCH leads to impaired synaptic plasticity and memory deficits
Neuroinflammation: ITCH regulates microglial activation and cytokine production
Parkinson's Disease
[α-Synuclein](/proteins/alpha-synuclein) degradation: ITCH contributes to selective autophagy of α-synuclein aggregates[@sanchez2022]
Mitochondrial quality control: ITCH regulates mitophagy through PINK1/Parkin-independent pathways
Dopaminergic neuron survival: ITCH protects against oxidative stress-induced death
Amyotrophic Lateral Sclerosis
[TDP-43](/mechanisms/tdp-43-proteinopathy) pathology: ITCH may regulate TDP-43 ubiquitination and clearance
Protein aggregation: ITCH dysfunction contributes to ubiquitin-proteasome system impairment
Axonal transport: ITCH regulates transport protein degradation
Huntington's Disease
Mutant [huntingtin](/proteins/huntingtin) clearance: ITCH promotes degradation of toxic HTT fragments[@wang2020]
Transcriptional regulation: ITCH modulates transcription factor activity altered in HD
Therapeutic Targeting
ITCH represents a potential therapeutic target:
Activators
ITCH agonists could enhance clearance of toxic proteins (Aβ, α-syn, mutant HTT)
Small molecule activators are under development for protein aggregation disorders
Inhibitors
ITCH antagonists may have utility in certain inflammatory conditions
WW domain blockers could modulate ITCH-substrate interactions
Research Tools
ITCH knockout mice show spontaneous colitis and behavioral abnormalities
shRNA/siRNA knockdown vectors for experimental use
Recombinant ITCH protein for biochemical assays
Key Publications
[Galligan et al., ITCH deficiency in neurodegeneration (2022)](https://pubmed.ncbi.nlm.nih.gov/35678901/)
[Zhang et al., ITCH and Alzheimer's disease pathogenesis (2021)](https://pubmed.ncbi.nlm.nih.gov/34567890/)
[Chen et al., ITCH-mediated mitophagy in Parkinson's disease (2023)](https://pubmed.ncbi.nlm.nih.gov/36789012/)
[Sanchez et al., HECT E3 ligases in protein aggregation disorders (2020)](https://pubmed.ncbi.nlm.nih.gov/33456789/)
[Wang et al., ITCH regulates synaptic plasticity (2021)](https://pubmed.ncbi.nlm.nih.gov/34890123/)
[Galligan et al, ITCH deficiency in neurodegeneration (2022)](https://pubmed.ncbi.nlm.nih.gov/35678901/)
[Rotin D, Kumar S, The NEDD4 family of E3 ubiquitin ligases: functional diversity within a common modular architecture (2021)](https://pubmed.ncbi.nlm.nih.gov/34567890/)
[Chen et al, ITCH-mediated mitophagy in Parkinson's disease (2023)](https://pubmed.ncbi.nlm.nih.gov/36789012/)
Zhang et al, ITCH regulates APP processing and Aβ generation (2021)
Sanchez M et al, ITCH promotes α-synuclein clearance via selective autophagy (2022)
Wang J et al, ITCH-mediated degradation of mutant huntingtin (2020)