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)[1]. 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[2].
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)[3]. This page provides a comprehensive overview of CHMP3's molecular function, structure, disease associations, and therapeutic implications.
| Property | Value |
|---|---|
| Gene Symbol | CHMP3 |
| Full Name | Charged Multivesicular Body Protein 3 |
| Alternative Names | DID2, VPS24, CHMP24 |
| Chromosomal Location | 2p21 |
| NCBI Gene ID | 25973 |
| OMIM ID | 609538 |
| Ensembl ID | ENSG00000115159 |
| UniProt ID | Q9Y3E0 |
| Protein Length | 222 amino acids |
| Molecular Weight | ~24 kDa |
| Associated Diseases | Neurodegeneration, lysosomal storage disorders, ALS, AD |
CHMP3 belongs to the CHMP (Charged Multivesicular Body Protein) family, which consists of structurally related ESCRT-III proteins[4]. The protein contains several key structural features:
Cryo-EM studies have revealed that CHMP3 adopts a helical polymeric structure when assembled into ESCRT-III filaments[5]. The protein can transition between:
This conformational switch is critical for its function in membrane remodeling.
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[1:1]. The ESCRT-III complex in mammals includes several related proteins:
The assembly of ESCRT-III on endosomal membranes proceeds through a carefully orchestrated sequence:
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:
CHMP3 is a core component of ESCRT-III involved in the final stages of MVB formation[6]:
Key Functions in MVB Biogenesis:
CHMP3 plays a crucial role in autophagic degradation pathways[7][8]:
The autophagy pathway intersects with ESCRT-III function through several mechanisms:
| Autophagy Type | CHMP3 Role |
|---|---|
| Macroautophagy | Membrane remodeling for autophagosome formation |
| Selective autophagy | Recognition and clearance of protein aggregates |
| Mitophagy | Mitochondrial turnover and quality control |
| Lysosomal fusion | Direct involvement in autophagosome-lysosome fusion |
Beyond MVB formation, CHMP3 participates in several autophagic pathways that are critical for neuronal health[2:1]:
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:
Endosomal-Lysosomal Pathway: CHMP3 bridges endosomal trafficking with autophagic pathways, ensuring proper delivery of cargo to lysosomes for degradation.
Beyond endosomal trafficking, CHMP3 participates in the final stages of cell division[6:1]:
In neurons, CHMP3 has specialized functions related to the unique architecture and physiology of these cells[9][10]:
Synaptic Function: CHMP3 plays important roles at synapses, the specialized junctions where neurons communicate:
Axonal Transport and Integrity: Neurons depend on efficient axonal transport systems. CHMP3 contributes to axonal integrity through:
CHMP3 shows broad expression across multiple tissue types:
| Tissue | Expression Level |
|---|---|
| Brain (cortex, hippocampus, substantia nigra) | High |
| Lung | High |
| Heart | Moderate |
| Liver | Moderate |
| Kidney | Moderate |
| Testis | High |
| Most other tissues | Moderate |
Within the brain, CHMP3 is expressed in:
CHMP3 localizes to:
CHMP3 dysfunction contributes to AD pathogenesis through multiple mechanisms[11]:
Key Evidence:
CHMP3 plays important roles in PD pathogenesis[12]:
Key Evidence:
CHMP3 and other ESCRT-III components are implicated in ALS[3:1]:
The following pathways link CHMP3 dysfunction to neuronal death:
CHMP3 interacts with several key proteins relevant to neurodegeneration:
| Partner Protein | Interaction Type | Functional Relevance |
|---|---|---|
| CHMP2B | Direct binding | Co-polymerization in ESCRT-III |
| CHMP4A/B | Direct binding | Complex formation |
| VPS4B | ATPase regulation | Disassembly of ESCRT-III |
| ALIX | Bridging protein | Broader ESCRT function |
| Ubiquitin | Binding | Cargo recognition |
Targeting CHMP3 and ESCRT-III function represents a promising therapeutic approach[13]:
Modulating CHMP3 and ESCRT-III function represents a therapeutic approach:
Enhancing Autophagic Flux: Pharmacological approaches:
CHMP3 and related ESCRT-III components may serve as[11:1][14]:
| Biomarker | Sample | Significance |
|---|---|---|
| CHMP3 expression | Brain tissue | Reduced in neurodegeneration |
| CHMP3 phosphorylation | CSF | Altered in ALS |
| Autophagic flux markers | Blood/CSF | Impaired in PD |
| Lysosomal function | Skin fibroblasts | Defective in some cases |
Hanson PI, Cashikar A. Multivesicular body morphogenesis. Annual Review of Cell and Developmental Biology. 2012. ↩︎ ↩︎
Lee JA, Liu L, Gao FB. Autophagy defects in neurodegenerative diseases. Aging Cell. 2019. ↩︎ ↩︎
Bauer I, et al. CHMP3 mutations in neurodegenerative disease. Human Molecular Genetics. 2013. ↩︎ ↩︎
Carlson LA, et al. Cryo-EM of the human ESCRT-III complex. Proceedings of the National Academy of Sciences. 2018. ↩︎
McCullough J, et al. Structure and function of the ESCRT-III complex. Nature Reviews Molecular Cell Biology. 2018. ↩︎
Agromayor M, et al. The ESCRT-III component CHMP3 is required for cytokinesis and cell-cell adhesion. PLoS ONE. 2010. ↩︎ ↩︎
Filimonenko M, et al. The selective macroautophagy of pathogens and aggregates. Journal of Cell Biology. 2010. ↩︎
Rusten TE, et al. ESCRT and autophagy's intertwined roles in membrane dynamics. Trends in Cell Biology. 2012. ↩︎
Metcalf D, et al. ESCRT-III dysfunction in neurodegeneration. Journal of Neuroscience. 2014. ↩︎
Sahin E, et al. CHMP3 and endosomal trafficking in neuronal cells. Molecular Biology of the Cell. 2015. ↩︎
Cheng L, et al. CHMP3 and lysosomal dysfunction in Alzheimer's disease. Acta Neuropathologica Communications. 2021. ↩︎ ↩︎
Liu Y, et al. ESCRT-III dysfunction in Parkinson's disease models. Cell Reports. 2024. ↩︎
Chen X, et al. Targeting ESCRT-III for neurodegenerative disease therapy. Nature Reviews Drug Discovery. 2022. ↩︎
Wilson S, et al. Endosomal sorting and autophagy in neurons. Trends in Neurosciences. 2023. ↩︎