VPS4A — Vacuolar Protein Sorting 4 Homolog A

Migration, Crosslink

📖

VPS4A — Vacuolar Protein Sorting 4 Homolog A

active

wiki page Created: 2026-04-02T07:19:26 By: crosslink-migration Quality: 50% ✓ SciDEX ID: wiki-genes-vps4a

📖 Wiki Page

gene1544 wordssynced 2026-04-02

VPS4A — Vacuolar Protein Sorting 4 Homolog A

Historical Discovery

The Vacuolar Protein Sorting (VPS) pathway was first characterized in yeast through genetic screens for mutants affecting vacuolar protein sorting. These screens identified VPS4 as a key gene required for normal vacuolar enzyme delivery. mammalian homologs were subsequently identified and characterized. The discovery of VPS4A as a human gene followed, with initial studies establishing its role in endosomal sorting and multivesicular body (MVB) formation. Subsequent research has expanded our understanding of VPS4A's roles in neuronal function and neurodegeneration, with genetic variants now implicated in Charcot-Marie-Tooth disease and other neurological conditions. The connection between ESCRT (Endosomal Sorting Complex Required for Transport) dysfunction and neurodegenerative diseases has become increasingly clear, placing VPS4A at the intersection of membrane trafficking and neuronal survival.

| Attribute | Value |
|-----------|-------|
| Symbol | VPS4A |
| Full Name | Vacuolar Protein Sorting 4 Homolog A |
| Chromosomal Location | 16q22.1 |
| NCBI Gene ID | [27183](https://www.ncbi.nlm.nih.gov/gene/27183) |
| OMIM | [609434](https://www.omim.org/entry/609434) |
| Ensembl ID | ENSG00000167842 |
| UniProt ID | [Q9Y5X0](https://www.uniprot.org/uniprot/Q9Y5X0) |
| Protein Class | AAA+ ATPase |
| Associated Diseases | Charcot-Marie-Tooth Disease, ALS, FTD, Breast Cancer |

</div>

Overview

...

VPS4A — Vacuolar Protein Sorting 4 Homolog A

Historical Discovery

The Vacuolar Protein Sorting (VPS) pathway was first characterized in yeast through genetic screens for mutants affecting vacuolar protein sorting. These screens identified VPS4 as a key gene required for normal vacuolar enzyme delivery. mammalian homologs were subsequently identified and characterized. The discovery of VPS4A as a human gene followed, with initial studies establishing its role in endosomal sorting and multivesicular body (MVB) formation. Subsequent research has expanded our understanding of VPS4A's roles in neuronal function and neurodegeneration, with genetic variants now implicated in Charcot-Marie-Tooth disease and other neurological conditions. The connection between ESCRT (Endosomal Sorting Complex Required for Transport) dysfunction and neurodegenerative diseases has become increasingly clear, placing VPS4A at the intersection of membrane trafficking and neuronal survival.

| Attribute | Value |
|-----------|-------|
| Symbol | VPS4A |
| Full Name | Vacuolar Protein Sorting 4 Homolog A |
| Chromosomal Location | 16q22.1 |
| NCBI Gene ID | [27183](https://www.ncbi.nlm.nih.gov/gene/27183) |
| OMIM | [609434](https://www.omim.org/entry/609434) |
| Ensembl ID | ENSG00000167842 |
| UniProt ID | [Q9Y5X0](https://www.uniprot.org/uniprot/Q9Y5X0) |
| Protein Class | AAA+ ATPase |
| Associated Diseases | Charcot-Marie-Tooth Disease, ALS, FTD, Breast Cancer |

</div>

Overview

Mermaid diagram (expand to render)

VPS4A (Vacuolar Protein Sorting 4 Homolog A) encodes an AAA+ ATPase involved in endosomal sorting, multivesicular body formation, and autophagy. It plays critical roles in membrane protein trafficking and has been implicated in neurodegenerative diseases. The protein functions as part of the ESCRT (Endosomal Sorting Complex Required for Transport) machinery, which is essential for membrane budding and scission events throughout the cell.

Gene Structure and Protein Architecture

The VPS4A gene spans approximately 21 kb on chromosome 16q22.1 and encodes a 437-amino acid protein with a molecular weight of approximately 48 kDa. The protein adopts the typical AAA+ ATPase fold, consisting of an N-terminal MIT (Microtubule Interacting and Transport) domain, a central ATPase domain, and a C-terminal region involved in oligomerization.

Protein Domain Architecture

| Domain | Amino Acids | Function |
|--------|------------|----------|
| MIT domain | 1-75 | Endosomal binding, ESCRT-III interaction |
| ATPase domain | 150-350 | ATP hydrolysis, conformational change |
| C-terminal | 350-437 | Oligomerization, regulation |

The AAA+ ATPase domain contains the classic Walker A (P-loop) and Walker B motifs required for ATP binding and hydrolysis. ATP hydrolysis provides the energy for conformational changes that drive membrane scission events.

AAA+ ATPase Superfamily

VPS4A belongs to the AAA+ (ATPase Associated with various cellular Activities) superfamily, which includes proteins involved in diverse cellular processes:

| Protein | Function | Disease Relevance |
|---------|----------|----------------|
| VPS4A | Endosomal sorting | CMT, ALS |
| VPS4B | ESCRT function | Lysosomal storage |
| NSF | SNARE recycling | Synaptic function |
| Spastin | ER dynamics | Hereditary spastic paraplegia |
| Mitochondrialdynamics | Mitochondrial fission | Neuropathy |

Molecular Function

ESCRT Machinery

VPS4A functions as part of the ESCRT (Endosomal Sorting Complex Required for Transport) machinery, which consists of multiple protein complexes (ESCRT-0, -I, -II, -III) and associated proteins including VPS4A and VPS4B [@esrect2008]. The ESCRT machinery is responsible for sorting cargo proteins into intralumenal vesicles of multivesicular bodies (MVBs), a process essential for lysosomal degradation of membrane proteins.

The ESCRT pathway operates as follows:

Cargo recognition: ESCRT-0 recognizes ubiquitinated membrane proteins

ESCRT-I/II recruitment: Sequential recruitment of ESCRT-I and ESCRT-II

ESCRT-III activation: ESCRT-III polymerization drives membrane budding

VPS4A recruitment: VPS4A is recruited to execute scission

ATP hydrolysis: VPS4A provides energy for scission and recycling

Multivesicular Body Formation

Multivesicular bodies (MVBs) are late endosomal compartments that contain intralumenal vesicles. MVB formation is essential for sorting cargo to lysosomes for degradation. VPS4A plays a critical role in the final stages of MVB formation [@mvb2010]:

Early endosome → Cargo sorting → ESCRT recruitment → MVB formation
↓
VPS4A-mediated scission → Intralumenal vesicle release
↓
Late MVB → Lysosomal fusion → Degradation

The scission reaction releases nascent vesicles into the MVB lumen. VPS4A's ATPase activity provides the energy for this process, and defects in VPS4A function impair MVB formation and cargo sorting.

Autophagy

VPS4A also plays important roles in autophagy, the process by which cells degrade and recycle cytoplasmic components. Autophagy is particularly important in neurons due to their post-mitotic nature and high metabolic demands [@autophagy2016]:

Autophagosome maturation: VPS4A affects autophagosome-lysosome fusion
Protein aggregate clearance: Required for clearance of aggregating proteins
Organelle quality control: Mediates mitophagy and ER-phagy
Stress response: Activated during cellular stress

Viral Budding

The ESCRT machinery, including VPS4A, is required for budding of many enveloped viruses. This has made viral budding a key model system for understanding VPS4A function. Importantly, viral budding does not require the full ESCRT machinery, instead relying on viral proteins that mimic ESCRT functions [@hiv bud2011].

Expression Pattern

VPS4A exhibits broad expression throughout the body with particular importance in tissues requiring high membrane trafficking activity:

Tissue Distribution

Brain: High expression in neurons throughout the CNS
Spinal cord: Particularly high in motor neurons
Peripheral nervous system: High in sensory and motor neurons
Heart: Moderate expression
Liver: Moderate expression
Kidney: High expression

Neuronal Expression

In neurons, VPS4A is enriched in:

Cell body: Perinuclear region
Axon: Distributed throughout
Dendrites: Postsynaptic compartments
Synaptic terminals: Pre- and postsynaptic

VPS4A localization is dynamic, changing in response to neuronal activity. Synaptic activation can alter VPS4A trafficking and function.

Signaling Pathways

Endosomal Trafficking Pathway

Receptor activation → Endocytosis → Early endosome → MVB → Lysosome
↓
ESCRT machinery → VPS4A → Recycling

Autophagy Pathway

Stress/Starvation → Autophagosome → VPS4A function → Autolysosome

Synaptic Vesicle Cycling

VPS4A participates in synaptic vesicle retrieval through endosomal sorting pathways. Recycling of synaptic vesicle proteins requires proper endosomal function, and VPS4A deficiency impairs this process [@synapse2022].

Disease Associations

Charcot-Marie-Tooth Disease (CMT2)

VPS4A mutations have been associated with axonal forms of Charcot-Marie-Tooth disease (CMT2), characterized by peripheral neuropathy with motor and sensory deficits [@cmt2014]:

Neuropathy phenotype: Progressive distal weakness and sensory loss
Inheritance: Autosomal dominant in reported families
Mechanism: Impaired endosomal sorting in peripheral neurons
Variation: Phenotypic variability even within families

The connection between VPS4A and CMT highlights the importance of membrane trafficking in long peripheral axons, which rely heavily on axonal transport.

Amyotrophic Lateral Sclerosis (ALS)

Multiple lines of evidence connect VPS4A to ALS pathogenesis [@als2013; @müller2014]:

Expression changes: Altered VPS4A expression in ALS motor neurons
TDP-43 connection: Impaired trafficking affects TDP-43 localization [@tardbp2017]
Protein aggregation: Defects in autophagic clearance contribute to aggregation
Genetic susceptibility: Some VPS4A variants modify ALS risk

Frontotemporal Dementia (FTD)

TDP-43 proteinopathy: Similar mechanisms to ALS
Protein trafficking: Impaired endosomal function affects FTD proteins
Lysosomal dysfunction: Links to FTD subtypes

Other Neurological Conditions

Huntington's Disease

Vesicle trafficking affected by mutant huntingtin
May modulate disease severity

Parkinson's Disease

Endosomal dysfunction affects alpha-synuclein clearance
Connection to lysosomal function

Therapeutic Implications

Drug Development

VPS4A represents a potential therapeutic target for multiple conditions:

Small Molecule Modulators

ATPase inhibitors: Targeting catalytic activity
ESCRT assembly modulators: Affecting complex formation
Allosteric regulators: Conformational changes

Biological Approaches

Gene therapy: Delivering functional VPS4A
AAV delivery to CNS
Small interfering RNA

Research Directions

Understanding tissue-specific VPS4A functions
Developing brain-penetrant modulators
Biomarker development

Protein Interactions

VPS4A interacts with several key proteins:

| Interactor | Function | Interaction Type |
|-----------|----------|----------------|
| CHMP2B | ESCRT-III | Direct binding |
| CHMP4B/C | ESCRT-III | Direct binding |
| ALIX | ESCRT accessory | Indirect |
| UBPY | Deubiquitinating enzyme | Regulation |
| Spartin | Atlastin regulation | Indirect |

Key Research Findings

2005: Initial characterization in neurodegeneration [@skibinski2005]

2008: ESCRT function in neurons defined [@esrect2008]

2010: MVB formation mechanism [@mvb2010]

2011: Viral budding studies [@hiv bud2011]

2012: ESCRT and neurodegeneration reviewed [@hanson2012]

2013: ALS connection established [@als2013]

2014: CMT association identified [@cmt2014]

2016: Autophagy role characterized [@autophagy2016]

2017: TDP-43 connection [@tardbp2017]

2019: Exosome release role [@exosome2019]

2020: Lysosomal trafficking [@lysosome2020]

2021: Signaling regulation [@signaling2021]

2022: Synaptic function [@synapse2022]

2023: Therapeutic targeting [@therapy2023]

External Links

[NCBI Gene: VPS4A](https://www.ncbi.nlm.nih.gov/gene/27183)
[UniProt: VPS4A](https://www.uniprot.org/uniprot/Q9Y5X0)
[OMIM: VPS4A](https://www.omim.org/entry/609434)
[Ensembl: VPS4A](https://www.ensembl.org/Homo_sapiens/Gene/Summary?g=ENSG00000167842)
[GeneCards: VPS4A](https://www.genecards.org/cgi-bin/carddisp.pl?gene=VPS4A)

References

[McGough et al., VPS4A mutations in CMT disease (2017)](https://pubmed.ncbi.nlm.nih.gov/28334386/)

[Hanson et al., ESCRT and neurodegeneration (2012)](https://pubmed.ncbi.nlm.nih.gov/22577063/)

[Skibinski et al., Endosomal trafficking in ALS (2005)](https://pubmed.ncbi.nlm.nih.gov/15657581/)

[Hanson et al., ESCRT function in neurons (2008)](https://doi.org/10.1038/nrn2425)

[Hanson et al., Multivesicular body formation (2010)](https://doi.org/10.1083/jcb.201001039)

[Bieniasz et al., VPS4 and viral budding (2011)](https://doi.org/10.1016/j.virol.2011.02.011)

[Urwin et al., VPS4A in ALS pathogenesis (2013)](https://doi.org/10.1093/brain/awt053)

[Lupas et al., CMT2A and VPS4A (2014)](https://doi.org/10.1212/WNL.0000000000000127)

[Eskelinen et al., VPS4A in autophagy (2016)](https://doi.org/10.1080/15548627.2016.1159378)

[Riffe et al., VPS4A and TDP-43 (2017)](https://doi.org/10.1186/s13024-017-0184-3)

[Sadasivan et al., VPS4A in neuronal development (2018)](https://doi.org/10.1016/j.devcel.2018.10.012)

[Zhang et al., VPS4A and exosome release (2019)](https://doi.org/10.1002/jev2.12345)

[Settembre et al., VPS4A and lysosomal trafficking (2020)](https://doi.org/10.1038/s41556-020-0487-9)

[Raiborg et al., VPS4A in cell signaling (2021)](https://doi.org/10.1016/j.tcb.2021.02.005)

[Kennedy et al., VPS4A in synaptic function (2022)](https://doi.org/10.1016/j.neuron.2022.04.015)

[Chen et al., ESCRT-targeted therapy (2023)](https://doi.org/10.1016/j.ymthe.2023.01.012)

[Müller et al., ALS genetics and ESCRT (2014)](https://doi.org/10.1007/s00401-014-1291-1)

Pathway Diagram

The following diagram shows the key molecular relationships involving VPS4A — Vacuolar Protein Sorting 4 Homolog A discovered through SciDEX knowledge graph analysis:

Mermaid diagram (expand to render)

📖 View canonical wiki page →

Related Entities

VPS4A

▸Metadataorigin_type: v1_polymorphic_backfill

slug	genes-vps4a
kg_node_id	VPS4A
entity_type	gene
origin_type	v1_polymorphic_backfill
source_table	wiki_pages
wiki_page_id	wp-c36a8f9dc222
__merged_from	{'merged_at': '2026-05-13', 'unprefixed_id': 'genes-vps4a'}
_schema_version	1

📊 Evidence Profile Foundational

Evidence Balance

+0%

Certainty

70%

Debates

0

Incoming

14

Outgoing

33

0 supporting 0 contradicting 0 neutral

View full evidence profile →

Public annotations (0)Annotate on Hypothes.is →

No public annotations yet.

📗 Cite This Artifact

VPS4A — Vacuolar Protein Sorting 4 Homolog A

VPS4A — Vacuolar Protein Sorting 4 Homolog A

Historical Discovery

Overview

VPS4A — Vacuolar Protein Sorting 4 Homolog A

Historical Discovery

Overview

Gene Structure and Protein Architecture

Protein Domain Architecture

AAA+ ATPase Superfamily

Molecular Function

ESCRT Machinery

Multivesicular Body Formation

Autophagy

Viral Budding

Expression Pattern

Tissue Distribution

Neuronal Expression

Signaling Pathways

Endosomal Trafficking Pathway

Autophagy Pathway

Synaptic Vesicle Cycling

Disease Associations

Charcot-Marie-Tooth Disease (CMT2)

Amyotrophic Lateral Sclerosis (ALS)

Frontotemporal Dementia (FTD)

Other Neurological Conditions

Therapeutic Implications

Drug Development

Research Directions

Protein Interactions

Key Research Findings

See Also

External Links

References

Pathway Diagram

💬 Discussion