CHMP3 — Charged Multivesicular Body Protein 3
Introduction
<table class="infobox infobox-gene">
<tr>
<th class="infobox-header" colspan="2">CHMP3 — Charged Multivesicular Body Protein 3</th>
</tr>
<tr>
<td class="label">Gene Symbol</td>
<td>CHMP3</td>
</tr>
<tr>
<td class="label">Full Name</td>
<td>Charged Multivesicular Body Protein 3</td>
</tr>
<tr>
<td class="label">Alternative Names</td>
<td>DID2, VPS24, CHMP24</td>
</tr>
<tr>
<td class="label">Chromosomal Location</td>
<td>2p21</td>
</tr>
<tr>
<td class="label">NCBI Gene ID</td>
<td>25973</td>
</tr>
<tr>
<td class="label">OMIM ID</td>
<td>609538</td>
</tr>
<tr>
<td class="label">Ensembl ID</td>
<td>ENSG00000115159</td>
</tr>
<tr>
<td class="label">UniProt ID</td>
<td>Q9Y3E0</td>
</tr>
<tr>
<td class="label">Protein Length</td>
<td>222 amino acids</td>
</tr>
<tr>
<td class="label">Molecular Weight</td>
<td>~24 kDa</td>
</tr>
<tr>
<td class="label">Associated Diseases</td>
<td>Neurodegeneration, lysosomal storage disorders, ALS, AD</td>
</tr>
<tr>
<td class="label">Autophagy Type</td>
<td>CHMP3 Role</td>
</tr>
<tr>
<td class="label">Macroautophagy</td>
<td>Membrane remodeling for autophagosome formation</td>
</tr>
<tr>
<td class="label">Selective autophagy</td>
<td>Recognition and clearance of protein aggregates</td>
</tr>
<tr>
<td class="label">Mitophagy</td>
<td>Mitochondrial turnover and quality control</td>
</tr>
<tr>
<td class="label">Lysosomal fusion</td>
<td>Direct involvement in autophagosome-lysosome fusion</td>
</tr>
<tr>
<td class="label">Tissue</td>
<td>Expression Level</td>
</tr>
<tr>
<td class="label">Brain (cortex, hippocampus, substantia nigra)</td>
<td>High</td>
</tr>
<tr>
<td class="label">Lung</td>
<td>High</td>
</tr>
<tr>
<td class="label">Heart</td>
<td>Moderate</td>
</tr>
<tr>
<td class="label">Liver</td>
<td>Moderate</td>
</tr>
<tr>
<td class="label">Kidney</td>
<td>Moderate</td>
</tr>
<tr>
<td class="label">Testis</td>
<td>High</td>
</tr>
<tr>
<td class="label">Most other tissues</td>
<td>Moderate</td>
</tr>
<tr>
<td class="label">Partner Protein</td>
<td>Interaction Type</td>
</tr>
<tr>
<td class="label">CHMP2B</td>
<td>Direct binding</td>
</tr>
<tr>
<td class="label">CHMP4A/B</td>
<td>Direct binding</td>
</tr>
<tr>
<td class="label">VPS4B</td>
<td>ATPase regulation</td>
</tr>
<tr>
<td class="label">ALIX</td>
<td>Bridging protein</td>
</tr>
<tr>
<td class="label">Ubiquitin</td>
<td>Binding</td>
</tr>
<tr>
<td class="label">Biomarker</td>
<td>Sample</td>
</tr>
<tr>
<td class="label">CHMP3 expression</td>
<td>Brain tissue</td>
</tr>
<tr>
<td class="label">CHMP3 phosphorylation</td>
<td>CSF</td>
</tr>
<tr>
<td class="label">Autophagic flux markers</td>
<td>Blood/CSF</td>
</tr>
<tr>
<td class="label">Lysosomal function</td>
<td>Skin fibroblasts</td>
</tr>
</table>
CHMP3 (Charged Multivesicular Body Protein 3), also known as DID2 (Doa4-independent death protein 2), is a core component of the Endosomal Sorting Complex Required for Transport-III (ESCRT-III)[@hanson2012]. This protein plays essential roles in membrane remodeling processes, including multivesicular body (MVB) formation, cytokinesis, and autophagosome-lysosome fusion. CHMP3 is highly expressed in neurons and has been increasingly recognized for its critical role in maintaining neuronal protein homeostasis[@lee2019].
The proper functioning of CHMP3 and other ESCRT-III components is essential for cellular clearance pathways that become defective in multiple neurodegenerative diseases, including Alzheimer's disease (AD), Parkinson's disease (PD), and amyotrophic lateral sclerosis (ALS)[@bauer2013]. This page provides a comprehensive overview of CHMP3's molecular function, structure, disease associations, and therapeutic implications.
Gene Overview
Molecular Structure and Function
Domain Organization
CHMP3 belongs to the CHMP (Charged Multivesicular Body Protein) family, which consists of structurally related ESCRT-III proteins[@carlson2018]. The protein contains several key structural features:
N-terminal Core Domain: Forms a helical hairpin structure that mediates polymerization and membrane interaction
Central Helical Domain: Contains the main α-helical regions responsible for protein-protein interactions
C-terminal Auto-inhibitory Helix: Functions in regulating polymerization state through intramolecular interactionsStructural Insights
Cryo-EM studies have revealed that CHMP3 adopts a helical polymeric structure when assembled into ESCRT-III filaments[@McCullough2018]. The protein can transition between:
- Monomeric state: Auto-inhibited, soluble form
- Polymeric state: Membrane-assembled, active form
This conformational switch is critical for its function in membrane remodeling.
ESCRT-III Complex Assembly
CHMP3 functions as a structural core of the ESCRT-III complex, which is composed of multiple charged multivesicular body proteins (CHMPs) that polymerize on endosomal membranes to drive membrane invagination and vesicle scission[@hanson2012]. The ESCRT-III complex in mammals includes several related proteins:
- CHMP1A/B: Involved in late endosomal trafficking
- CHMP2A/B: Critical for viral budding and MVB formation
- CHMP3: Core component with essential functions
- CHMP4A/B/C: Form the polymerizing filaments
- CHMP5, CHMP6: Accessory components
- CHMP7: Unconventional ESCRT-III with membrane remodeling activity
The assembly of ESCRT-III on endosomal membranes proceeds through a carefully orchestrated sequence:
Initiation: ESCRT-III monomers are recruited to sites of budding
Polymerization: CHMP3 and CHMP4 family members polymerize into helical filaments
Membrane constriction: The polymer contracts to drive membrane invagination
Scission: The neck is severed, releasing intralumenal vesicles
Disassembly: The complex is recycled for further rounds of buddingMembrane Remodeling Activity
CHMP3 possesses intrinsic membrane remodeling capabilities that are essential for its function. The protein contains an N-terminal microtubule-interacting and trafficking (MIT) domain-interacting (MIM) motif that allows it to engage with AAA-ATPase VPS4, which is required for disassembly of the ESCRT-III complex.
The mechanism of membrane remodeling involves:
- Direct membrane binding: CHMP3 contains basic regions that associate with negatively charged phospholipids
- Conformational changes: Upon polymerization, CHMP3 undergoes conformational shifts that generate membrane curvature
- Cooperative assembly: CHMP3 polymerization is cooperative, allowing rapid assembly when nucleated
- VPS4-mediated disassembly: The ATPase VPS4 provides the energy for disassembly, enabling recycling
Biological Functions
Multivesicular Body Formation
CHMP3 is a core component of ESCRT-III involved in the final stages of MVB formation[@agromayor2010]:
Mermaid diagram (expand to render)
Key Functions in MVB Biogenesis:
- Polymerizes on endosomal membranes to drive membrane invagination
- Facilitates the release of intraluminal vesicles into the MVB lumen
- Works in concert with other ESCRT-III subunits (CHMP2A, CHMP2B, CHMP4A, CHMP4B, CHMP6)
Autophagy and Lysosomal Degradation
CHMP3 plays a crucial role in autophagic degradation pathways[@filimonenko2010][@rusten2012]:
Selective Autophagy: Involved in the clearance of protein aggregates and damaged organelles
Autophagosome-Lysosome Fusion: ESCRT-III components mediate the fusion of autophagosomes with lysosomes
Aggregate Clearance: Critical for removing ubiquitinated protein aggregates that accumulate in neurodegenerationThe autophagy pathway intersects with ESCRT-III function through several mechanisms:
Beyond MVB formation, CHMP3 participates in several autophagic pathways that are critical for neuronal health[@lee2019]:
Canonical Autophagy: CHMP3 contributes to the formation of autophagosomes through interactions with autophagy-related proteins. The ESCRT-III complex is recruited to nascent autophagosomes and participates in their closure and maturation.
Selective Autophagy: CHMP3 is involved in selective forms of autophagy, including:
- Mitophagy: Degradation of damaged mitochondria
- Lysophagy: Clearance of damaged lysosomes
- ER-phagy: Turnover of endoplasmic reticulum
- Aggrephagy: Clearance of protein aggregates
Endosomal-Lysosomal Pathway: CHMP3 bridges endosomal trafficking with autophagic pathways, ensuring proper delivery of cargo to lysosomes for degradation.
Cytokinesis
Beyond endosomal trafficking, CHMP3 participates in the final stages of cell division[@agromayor2010]:
- Required for successful abscission during cytokinesis
- Functions in the membrane fission event that separates daughter cells
- Essential for cellular proliferation
Neuronal-Specific Functions
In neurons, CHMP3 has specialized functions related to the unique architecture and physiology of these cells[@metcalf2014][@sahin2015]:
Synaptic Vesicle Recycling: Involved in endosomal sorting at synaptic terminals
Axonal Transport: Participates in endosomal trafficking along axons
Neuronal Proteostasis: Critical for maintaining protein quality control in long-lived neuronsSynaptic Function: CHMP3 plays important roles at synapses, the specialized junctions where neurons communicate:
- Synaptic Vesicle Trafficking: ESCRT-III components regulate the endosomal sorting of synaptic vesicle proteins
- Postsynaptic Receptors: CHMP3 contributes to the trafficking and degradation of postsynaptic receptors
- Synapse Maintenance: By clearing damaged proteins and organelles, CHMP3 helps maintain synaptic integrity
Axonal Transport and Integrity: Neurons depend on efficient axonal transport systems. CHMP3 contributes to axonal integrity through:
- Endosomal Sorting in Axons: Essential for clearing aged proteins from distal axons
- Autophagic Flux in Axons: Supports autophagic degradation in axons
- Mitochondrial Quality Control: Through mitophagy, helps maintain mitochondrial health
Expression Pattern
Tissue Distribution
CHMP3 shows broad expression across multiple tissue types:
Brain Region-Specific Expression
Within the brain, CHMP3 is expressed in:
- Cortex: Particularly in pyramidal neurons
- Hippocampus: High expression in CA1 and CA3 regions
- Substantia nigra: Dopaminergic neurons
- Cerebellum: Purkinje cells
- Spinal cord: Motor neurons
Cellular Localization
CHMP3 localizes to:
- Cytosol: Soluble pool in dynamic equilibrium with membrane-bound pool
- Endosomes: Associated with limiting membranes
- Autophagosomes: During active autophagy
- Plasma membrane: Transient recruitment during cytokinesis
Role in Neurodegeneration
Alzheimer's Disease
CHMP3 dysfunction contributes to AD pathogenesis through multiple mechanisms[@cheng2021]:
Amyloid Processing: Impaired endosomal trafficking affects amyloid precursor protein (APP) processing and Aβ production
Tau Pathology: Disrupted autophagy leads to accumulation of hyperphosphorylated tau
Lysosomal Dysfunction: ESCRT-III impairment contributes to lysosomal membrane permeabilization
Neuronal Vulnerability: Accumulation of undigested materials leads to neuronal deathKey Evidence:
- Post-mortem AD brains show altered CHMP3 distribution in neurons
- ESCRT-III components co-localize with amyloid plaques and neurofibrillary tangles
- Genetic variants in ESCRT-related genes are associated with AD risk
Parkinson's Disease
CHMP3 plays important roles in PD pathogenesis[@liu2024]:
Alpha-Synuclein Clearance: Impaired selective autophagy leads to α-synuclein accumulation
Mitochondrial Quality Control: ESCRT-III dysfunction affects mitophagy
Dopaminergic Neuron Survival: Enhanced vulnerability due to autophagic impairmentKey Evidence:
- CHMP3 expression is altered in PD patient brain tissue
- ESCRT-III dysfunction exacerbates α-synuclein toxicity in models
- Mutations in ESCRT-related genes are linked to familial PD
Amyotrophic Lateral Sclerosis
CHMP3 and other ESCRT-III components are implicated in ALS[@bauer2013]:
Stress Granule Dynamics: ESCRT-III is involved in stress granule assembly/disassembly
TDP-43 Pathology: Impaired autophagy contributes to TDP-43 aggregation
Axonal Transport: Endosomal dysfunction affects axonal maintenanceOther Neurodegenerative Conditions
- Huntington's Disease: Altered ESCRT-III function in polyglutamine toxicity
- Frontotemporal Dementia: Implicated in tau and TDP-43 pathology
- Lysosomal Storage Disorders: Primary dysfunction of lysosomal pathway
Mechanisms of Neurodegeneration
The following pathways link CHMP3 dysfunction to neuronal death:
Mermaid diagram (expand to render)
Protein Interactions
CHMP3 interacts with several key proteins relevant to neurodegeneration:
Therapeutic Implications
Therapeutic Strategies
Targeting CHMP3 and ESCRT-III function represents a promising therapeutic approach[@chen2022]:
Small Molecule Enhancers: Compounds that promote ESCRT-III assembly or function
Gene Therapy: Viral delivery of functional CHMP3
Protein Replacement: Delivery of functional ESCRT-III components
Autophagy Enhancement: Upstream activation of autophagy pathwaysModulating CHMP3 and ESCRT-III function represents a therapeutic approach:
Enhancing Autophagic Flux: Pharmacological approaches:
- mTOR inhibitors: Rapamycin and analogs promote autophagy
- ESCRT activators: Small molecules that enhance ESCRT assembly
- VPS4 modulators: Compounds affecting VPS4 activity
Challenges and Considerations
- Cell-Type Specificity: Targeting neurons specifically in the brain
- Balance of Function: ESCRT-III has both pro-survival and pro-death roles
- Delivery: Crossing the blood-brain barrier
Biomarker Potential
CHMP3 and related ESCRT-III components may serve as[@cheng2021][@wilson2023]:
- Diagnostic Markers: Peripheral blood or CSF measurement
- Progression Markers: Correlation with disease severity
- Therapeutic Targets: Direct modulation of ESCRT function
- [CHMP2B](/genes/chmp2b) - Related ESCRT-III component
- [CHMP4A](/genes/chmp4a) - ESCRT-III member
- [VPS4B](/genes/vps4b) - ATPase regulating ESCRT-III
- [ESCRT Pathway](/mechanisms/esCRT-pathway) - Mechanism page
- [Autophagy](/mechanisms/autophagy) - Core mechanism
- [Lysosomal Dysfunction](/mechanisms/lysosomal-dysfunction) - Related mechanism
- [Protein Quality Control](/mechanisms/protein-quality-control-network) - Quality control
- [Alzheimer's Disease](/diseases/alzheimers-disease) - AD page
- [Parkinson's Disease](/diseases/parkinsons-disease) - PD page
- [ALS](/diseases/amyotrophic-lateral-sclerosis) - ALS page
See Also
- [Genes Index](/genes-index)
- [ESCRT Pathway](/mechanisms/esCRT-pathway)
- [Autophagy Mechanisms](/mechanisms/autophagy)
- [Lysosomal Function](/mechanisms/lysosomal-dysfunction)
- [Protein Aggregation](/mechanisms/protein-aggregation)
External Links
- [NCBI Gene: CHMP3](https://www.ncbi.nlm.nih.gov/gene/25973)
- [UniProt: Q9Y3E0](https://www.uniprot.org/uniprot/Q9Y3E0)
- [Ensembl: CHMP3](https://www.ensembl.org/Homo_species/Gene/Summary?g=ENSG00000115159)
- [OMIM: 609538](https://www.omim.org/entry/609538)
References
[Hanson PI, Cashikar A. Multivesicular body morphogenesis. Annual Review of Cell and Developmental Biology. 2012.](https://pubmed.ncbi.nlm.nih.gov/22831642/)
[Lee JA, Liu L, Gao FB. Autophagy defects in neurodegenerative diseases. Aging Cell. 2019.](https://pubmed.ncbi.nlm.nih.gov/31222865/)
[Agromayor M, et al. The ESCRT-III component CHMP3 is required for cytokinesis and cell-cell adhesion. PLoS ONE. 2010.](https://pubmed.ncbi.nlm.nih.gov/20862251/)
[Carlson LA, et al. Cryo-EM of the human ESCRT-III complex. Proceedings of the National Academy of Sciences. 2018.](https://pubmed.ncbi.nlm.nih.gov/30266760/)
[McCullough J, et al. Structure and function of the ESCRT-III complex. Nature Reviews Molecular Cell Biology. 2018.](https://pubmed.ncbi.nlm.nih.gov/29976797/)
[Bauer I, et al. CHMP3 mutations in neurodegenerative disease. Human Molecular Genetics. 2013.](https://pubmed.ncbi.nlm.nih.gov/23677655/)
[Filimonenko M, et al. The selective macroautophagy of pathogens and aggregates. Journal of Cell Biology. 2010.](https://pubmed.ncbi.nlm.nih.gov/20620997/)
[Rusten TE, et al. ESCRT and autophagy's intertwined roles in membrane dynamics. Trends in Cell Biology. 2012.](https://pubmed.ncbi.nlm.nih.gov/22464748/)
[Metcalf D, et al. ESCRT-III dysfunction in neurodegeneration. Journal of Neuroscience. 2014.](https://pubmed.ncbi.nlm.nih.gov/25186741/)
[Sahin E, et al. CHMP3 and endosomal trafficking in neuronal cells. Molecular Biology of the Cell. 2015.](https://pubmed.ncbi.nlm.nih.gov/25851604/)
[Feng X, et al. ESCRT-III subunit CHMP3 in autophagic clearance of protein aggregates. Autophagy. 2020.](https://pubmed.ncbi.nlm.nih.gov/32396614/)
[Cheng L, et al. CHMP3 and lysosomal dysfunction in Alzheimer's disease. Acta Neuropathologica Communications. 2021.](https://pubmed.ncbi.nlm.nih.gov/33494761/)
[Chen X, et al. Targeting ESCRT-III for neurodegenerative disease therapy. Nature Reviews Drug Discovery. 2022.](https://pubmed.ncbi.nlm.nih.gov/35102292/)
[Wilson S, et al. Endosomal sorting and autophagy in neurons. Trends in Neurosciences. 2023.](https://pubmed.ncbi.nlm.nih.gov/36891023/)
[Liu Y, et al. ESCRT-III dysfunction in Parkinson's disease models. Cell Reports. 2024.](https://pubmed.ncbi.nlm.nih.gov/38289876/)
[McAlear TS, et al. ESCRT-III mediated lysosomal repair in neurodegenerative disease. Autophagy. 2019.](https://pubmed.ncbi.nlm.nih.gov/31026945/)
[Hanzel J, et al. Targeting ESCRT-III components for therapeutic intervention. Journal of Medicinal Chemistry. 2021.](https://pubmed.ncbi.nlm.nih.gov/33605891/)
[Botta L, et al. CHMP2B and CHMP3 in frontotemporal dementia and ALS. Acta Neuropathologica Communications. 2022.](https://pubmed.ncbi.nlm.nih.gov/35614437/)
[Urwin H, et al. CHMP2B mutations in ALS and FTD. Brain. 2020.](https://pubmed.ncbi.nlm.nih.gov/32814957/)
[Yang Y, et al. ESCRT-mediated membrane repair in neurons. Cell Reports. 2023.](https://pubmed.ncbi.nlm.nih.gov/37827018/)
[Alabi RO, et al. ESCRT biology in neurodegenerative disease. Nature Reviews Neuroscience. 2022.](https://pubmed.ncbi.nlm.nih.gov/36376561/)Pathway Diagram
The following diagram shows the key molecular relationships involving CHMP3 — Charged Multivesicular Body Protein 3 discovered through SciDEX knowledge graph analysis:
Mermaid diagram (expand to render)