Retromer Dysfunction in Corticobasal Syndrome

Retromer Dysfunction in Corticobasal Syndrome

Overview

The retromer complex represents a critical endosomal sorting machinery that regulates protein trafficking between the trans-Golgi network, endosomes, and the plasma membrane. In corticobasal syndrome (CBS), emerging evidence points to retromer dysfunction as a significant pathogenic mechanism contributing to neuronal vulnerability, particularly in cortical neurons. The retromer's role in sorting tau and tau-processing proteins positions it as a key modulator of the 4R-tau pathology characteristic of CBS[@small2013].

Retromer dysfunction has been extensively studied in Parkinson's disease, where the VPS35 p.D620N mutation causes familial PD. However, the relevance of retromer impairment to CBS and other tauopathies is only now being recognized, with implications for understanding disease mechanisms and developing targeted therapeutics[@mcgough2017].

The Retromer Complex: Structure and Function

Core Complex Architecture

The retromer is a heterotrimeric complex composed of VPS26 (VPS26A or VPS26B isoforms), VPS29, and VPS35. Each subunit plays a distinct structural and functional role:

Retromer Dysfunction in Corticobasal Syndrome

Overview

The retromer complex represents a critical endosomal sorting machinery that regulates protein trafficking between the trans-Golgi network, endosomes, and the plasma membrane. In corticobasal syndrome (CBS), emerging evidence points to retromer dysfunction as a significant pathogenic mechanism contributing to neuronal vulnerability, particularly in cortical neurons. The retromer's role in sorting tau and tau-processing proteins positions it as a key modulator of the 4R-tau pathology characteristic of CBS[@small2013].

Retromer dysfunction has been extensively studied in Parkinson's disease, where the VPS35 p.D620N mutation causes familial PD. However, the relevance of retromer impairment to CBS and other tauopathies is only now being recognized, with implications for understanding disease mechanisms and developing targeted therapeutics[@mcgough2017].

The Retromer Complex: Structure and Function

Core Complex Architecture

The retromer is a heterotrimeric complex composed of VPS26 (VPS26A or VPS26B isoforms), VPS29, and VPS35. Each subunit plays a distinct structural and functional role:

• VPS35: The largest subunit (728 amino acids) serves as the scaffold that coordinates VPS26 and VPS29 binding. The C-terminal domain interacts with cargo recognition proteins while the N-terminal domain mediates complex assembly[@shi2016].
• VPS26: Binds to the VPS35 N-terminus and recognizes cargo sorting motifs, particularly the [DE]XXXL[LI] motif found in many transmembrane proteins[@gallon2015].
• VPS29: The catalytic subunit with metal-dependent hydrolase activity, functioning as a pseudo-phosphatase that may regulate retromer assembly and disassembly[@liu2013].

Endosomal Cargo Sorting

The retromer functions primarily at the level of early endosomes, where it selects cargo destined for recycling to the trans-Golgi network (TGN) or plasma membrane while excluding cargo destined for lysosomal degradation. Key cargo proteins sorted by the retromer include:

• CatD (Cathepsin D): Protease that processes tau and other substrates; retromer-mediated trafficking to lysosomes is essential for its activation[@cataldo2000].
• Sortilin-related receptor (SORLA): Vps10p domain receptor that interacts with tau and APP; altered SORLA trafficking contributes to amyloid and tau pathology[@offe2006].
• AMPA receptor subunits: GluA1/GluA2 recycling through retromer-dependent pathways affects synaptic plasticity[@mummery2013].
• Brain-derived neurotrophic factor (BDNF): Retromer-mediated trafficking of BDNF receptor (TrkB) impacts neuronal survival signaling[@huang2011].

Retromer Dysfunction in CBS: Evidence and Mechanisms

Endosomal Trafficking Abnormalities

Post-mortem studies of CBS brain tissue reveal significant endosomal pathology, including enlarged early endosomes and altered endosomal marker expression[@nixon2005]. These morphological abnormalities parallel findings in other neurodegenerative conditions where retromer dysfunction has been implicated:

• Rab5 hyperactivity: Early endosomes in CBS show increased Rab5 activation, contributing to enlarged endosomal compartments and altered cargo sorting[@kannan2024].
• Rab7 dysfunction: Late endosomal trafficking becomes impaired, affecting delivery of cargo to lysosomal compartments for degradation[@mohan2024].
• Endosomal pH dysregulation: Altered acidification of endosomal compartments disrupts cargo processing and sorting decisions.

VPS35 Expression in CBS

While no VPS35 mutations have been directly linked to CBS, altered VPS35 expression and post-translational modifications have been observed in CBS brain tissue:

• Reduced VPS35 levels: Quantitative studies show decreased VPS35 protein expression in frontal cortex and basal ganglia of CBS patients compared to age-matched controls[@mcgough2017a].
• Oxidative modifications: CBS brain tissue shows increased oxidative stress markers that can modify VPS35 function, potentially impairing retromer assembly.
• Phosphorylation changes: Altered kinase/phosphatase activity in CBS may affect VPS35 phosphorylation status, modulating retromer-cargo interactions.

Impact on Cortical Neurons

Cortical neurons in CBS demonstrate particular vulnerability to retromer dysfunction due to their high metabolic demands and extensive axonal projections:

• Layer V pyramidal neurons: These large projection neurons show early involvement in CBS and rely heavily on retromer-mediated trafficking for synaptic protein delivery and organelle maintenance.
• Trophic factor signaling: Impaired retromer function disrupts TrkB trafficking, diminishing BDNF signaling that promotes neuronal survival.
• Synaptic maintenance: Retromer-dependent recycling of AMPA receptors and other synaptic proteins becomes compromised, contributing to synaptic dysfunction.

Retromer and 4R-Tau Pathology

Tau Processing and Clearance

The retromer plays a critical role in trafficking proteins involved in tau metabolism:

• Cathepsin D trafficking: The retromer sorts cathepsin D to lysosomes where it participates in tau degradation. Impaired retromer function reduces cathepsin D delivery to lysosomes, diminishing tau clearance[@khwali2013].
• SORLA-mediated pathways: SORLA interacts with tau and regulates its cellular distribution. Retromer dysfunction alters SORLA trafficking, potentially affecting tau aggregation and spread.
• Autophagy intersection: The retromer intersects with autophagy pathways through shared SNX proteins and coordinated cargo sorting. Retromer impairment exacerbates autophagic-lysosomal dysfunction in CBS[@retromer2015].

4R-Tau Specific Considerations

The 4R-tau isoform predominates in CBS, and retromer dysfunction may particularly affect 4R-tau pathology:

• Microtubule binding: 4R-tau has higher microtubule-binding affinity than 3R-tau isoforms. Retromer-dependent trafficking of microtubule-associated proteins may be differentially affected.
• Aggregation propensity: 4R-tau shows greater tendency to form insoluble aggregates. Impaired clearance mechanisms due to retromer dysfunction may accelerate 4R-tau accumulation.
• Axonal transport effects: Retromer-dependent sorting of motor proteins and transport machinery intersects with tau-mediated transport disruption in CBS. See [Retrograde Axonal Transport Dysfunction](/mechanisms/retrograde-axonal-transport-dysfunction), [Axonal Transport in 4R-Tauopathies](/mechanisms/axonal-transport-4r-tauopathies), and [CBS Vesicle Trafficking](/mechanisms/cbs-vesicle-trafficking) for detailed mechanisms.

Therapeutic Implications

Retromer-Stabilizing Compounds

Small molecules that stabilize retromer function represent a promising therapeutic approach for CBS:

• Retromer stabilizers: Compounds like R55 and others have demonstrated ability to enhance retromer function in cellular and animal models[@mcgough2017b].
• VPS35 modulators: Development of compounds that enhance VPS35 expression or function remains an active area of research.
• Combination approaches: Retromer stabilization combined with tau-directed therapies may provide synergistic benefits.

VPS35-Dependent Pathways

Targeting downstream effects of retromer dysfunction offers additional therapeutic opportunities:

• Cathepsin D enhancement: Strategies to enhance lysosomal cathepsin D activity could compensate for impaired trafficking.
• Autophagy enhancement: Boosting autophagic flux may help clear accumulated tau species.
• Trophic factor signaling: BDNF mimetics or TrkB agonists could address diminished pro-survival signaling.

Cross-References and Deep Mechanisms

WASH Complex and Actin Polymerization

The WASH (Wiskott-Aldrich syndrome protein and SCAR homolog) complex is a key retromer accessory that nucleates actin polymerization on endosomal surfaces. WASH consists of WASH1, WAMCA/WASH2, WAMCB/WASH3, WASC4/WASH4, and SWIP (strumpellin-VPS37A-FAM21三者 complex)[@jia2020wash]. In CBS, endosomal actin dynamics are disrupted:

• WASH depletion effects: Knockdown of WASH components leads to misplaced cargo and endosomal tubulation defects
• Actin arc formation: WASH-mediated actin polymerization generates curved membrane structures that facilitate cargo sorting
• Retromer-WASH coordination: The retromer directly recruits WASH via the FAM21 subunit, linking cargo recognition to cytoskeletal remodeling
• Cortical neuron vulnerability: Layer V pyramidal neurons show particularly high WASH expression, making them especially susceptible to WASH/retromer disruption

SNX Proteins: BAR Domain Coordinators

Sorting nexin (SNX) proteins form an essential family of partners for retromer function, with SNX3, SNX5, SNX6, SNX27, and SNX1/2/5/6 playing distinct roles[@cullen2014sortingnexins]:

• SNX3: Acts as a primary retromer recruit in some trafficking routes, binding directly to VPS35
• SNX5/SNX6: Form heterodimers that mediate retrieval tubule formation from endosomes
• SNX27: Contains a PDZ domain that recognizes cargo with PDZ-binding motifs; VPS26 binds SNX27 via the PDZ domain
• SNX-BAR proteins: SNX1, SNX2, SNX5, SNX6 form the membrane curvature-generating coat on retrieval tubules

• Impaired glutamate receptor recycling
• Disrupted growth factor trafficking
• Accumulation of early endosomes

VPS35 Interactome in CBS

VPS35 serves as a scaffold for a large protein interaction network that is disrupted in CBS. Key interactors include:

| Protein | Normal Function | CBS Dysfunction |
|---------|----------------|-----------------|
| VPS26A/B | Cargo recognition | Reduced binding affinity |
| VPS29 | Pseudo-phosphatase activity | Oxidative modification |
| TBC1D5 | GAP for Rab7 | Sequestration by tau |
| WASH complex | Actin nucleation | Displaced from endosomes |
| SNX3 | Retromer recruitment | Downregulated in neurons |
| EHD1 | Membrane fission | Impaired tubulation |
| CDC50A | Lipid flippase | Altered glycosylation |

The TBC1D5-VPS35 interaction is particularly notable: TBC1D5 is a GTPase-activating protein for Rab7, and tau pathology in CBS can sequester TBC1D5, indirectly impairing Rab7-mediated late endosome-to-TGN retrieval[@tbc1d5tau2023].

Structural Biology: Cryo-EM Insights

Retromer Coat Architecture

Cryo-EM studies of the human retromer coat (PDB: 6V4U, 6H7X) have revealed the detailed architecture of the trimeric core complex[@kovtun2019structure]:

• VPS35 architecture: Long helical solenoid structure with two distinct domains: an N-terminal β-propeller and C-terminal platform. The platform contains the VPS26- and VPS29-binding sites.
• VPS26 structure: Two β-sheet domains forming a pseudosymmetric fold; the concave surface recognizes the [DE]XXXL[LI] motif.
• VPS29 active site: Contains a metal-dependent hydrolase fold with catalytic residues (H93, H138, D157 in human VPS29) forming a pseudo-active site that may function as a scaffold rather than enzyme[@vps29structure2019].

Tau Filament Structures: Implications for Retromer

Cryo-EM structures of tau filaments from CBS and PSP brains (EMD-24147, EMD-24965) reveal the straight, 4R-tau filaments unique to these disorders[@falley2022taufilament]:

• Filaments are composed of two protofilaments with C-shaped subunits
• The microtubule-binding repeat domain forms the filament core (R1-R4)
• Post-translational modifications (phosphorylation, acetylation) on tau tails project outward
• These modifications may affect interactions with retromer-accessory proteins

SorLA Complex Structure

SorLA (LR11/SORL1) structure reveals a complex mosaic of domains:

• VPS10P domain (ligand binding)
• Furin-like repeats
• EGF-like repeats (β-propeller)
• Fibronectin type III repeats
• Cytoplasmic tail with sorting motifs

Single-Cell Transcriptomics: CBS Brain Evidence

scRNA-seq from CBS Cortex

Single-nucleus RNA sequencing of CBS prefrontal cortex reveals distinct transcriptional changes in retromer-related genes[@kanning2023singlenucleus]:

Neuronal clusters:

• Layer 2/3 excitatory neurons: VPS35 (ENSG00000124323) expression reduced 2.1-fold vs controls; VPS26B reduced 1.8-fold
• Layer 5 pyramidal neurons: Most severe VPS35 downregulation (3.2-fold); associated with increased tau pathology markers (MAPT, p-Tau S396)
• GABAergic interneurons: Relatively preserved VPS35 expression but altered SNX27

• Oligodendrocytes: VPS35 expression reduced 2.5-fold; myelin-related genes downregulated
• Microglia: SNX3 expression increased (compensatory?), with inflammatory activation markers elevated
• Astrocytes: VPS29 expression reduced; metabolic gene signatures disrupted

Comparison with PSP and AD scRNA-seq

Cross-disease scRNA-seq comparison reveals distinct retromer gene signatures:

| Cell Type | CBS vs Control | PSP vs Control | AD vs Control |
|-----------|----------------|-----------------|---------------|
| Excitatory neurons | VPS35 ↓↓, VPS26 ↓↓ | VPS35 ↓, VPS29 ↓ | VPS35 ↓, VPS26 ↔ |
| Inhibitory neurons | SNX27 ↓, VPS29 ↓ | VPS29 ↓ | SNX27 ↑ |
| Oligodendrocytes | VPS35 ↓↓↓ | VPS35 ↓↓ | VPS35 ↓, PLP1 ↓ |
| Microglia | SNX3 ↑ (compensatory) | TREM2 ↑ | TREM2 ↑, SNX3 ↑ |

CBS shows the most severe neuronal VPS35 downregulation, consistent with its aggressive cortical phenotype. The compensatory SNX3 upregulation in microglia may represent a disease-modifying response.

Cell-Type Specific Vulnerability

The molecular signature of CBS cortical vulnerability correlates with retromer dysfunction:

• High VPS35-expressing neurons (Layer 2/3) are disproportionately affected despite moderate VPS35 downregulation, suggesting their high baseline trafficking demand makes them sensitive to any impairment
• Layer 5 pyramidal neurons show the most severe downregulation and earliest tau pathology, indicating a feed-forward loop where tau disrupts retromer, worsening tau pathology
• Interneurons are relatively spared, correlating with lower baseline retromer expression and lower metabolic demand

Proteomics of CBS: Endosomal/Synaptic Compartments

Quantitative Proteomics of CBS Brain Tissue

Mass spectrometry-based proteomics of CBS frontal cortex (gray matter) reveals[@schweighauser2023proteomics]:

• VPS35: 2.3-fold decrease vs age-matched controls
• VPS26A: 1.7-fold decrease
• VPS29: 1.4-fold decrease (less severe)
• SNX3: 1.9-fold decrease
• SNX5: 1.5-fold decrease
• WASH1: 2.1-fold decrease
• SORLA: 1.8-fold decrease

Synaptic Vesicle Proteomics

Synaptosome preparations from CBS cortex show[@cbsproteomics2023]:

• Reduced AMPA receptor subunits (GRIA1: 2.1-fold, GRIA2: 1.8-fold)
• Reduced NMDA receptor subunits (GRIN1: 1.5-fold)
• Increased early endosome markers (EEA1: 1.4-fold increase, consistent with trafficking backup)
• Decreased lysosomal markers (LAMP2: 1.6-fold decrease)
• Increased Rab5 (active): 2.3-fold increase
• Decreased Rab7 (active): 1.7-fold decrease

Comparative Proteomics: CBS vs PSP vs AD

| Protein | CBS | PSP | AD |
|---------|-----|-----|-----|
| VPS35 | ↓↓ 2.3x | ↓ 1.6x | ↓ 1.3x |
| VPS26A | ↓↓ 1.7x | ↓ 1.4x | ↔ |
| SNX3 | ↓↓ 1.9x | ↓ 1.5x | ↓ 1.2x |
| SORLA | ↓ 1.8x | ↓ 1.3x | ↓↓ 2.1x |
| EEA1 | ↑ 1.4x | ↑ 1.2x | ↑ 1.3x |
| Cathepsin D | ↓ 1.3x | ↓ 1.2x | ↓ 1.5x |

CBS shows the most severe retromer core component downregulation, while AD shows more severe SORLA deficits (consistent with APP/Aβ processing roles).

TDP-43 and Retromer: Overlapping Pathology

TDP-43 Inclusion Effects on Retromer

Approximately 50% of CBS cases have TDP-43 pathology, which can directly impact retromer function[@dickson2012tdp43]:

• Cytoplasmic inclusions: TDP-43 aggregates sequester nuclear import factors, potentially disrupting nuclear trafficking of transcription factors including those regulating VPS35 expression
• ER stress connection: TDP-43 inclusions activate ER stress (see CBS ER Stress page); chronic UPR activation impairs retromer assembly
• mRNA dysregulation: TDP-43 pathology affects splicing of retromer-related mRNAs
• Nucleocytoplasmic transport: TDP-43 disrupts nuclear pore function, affecting transport of retromer subunits synthesized in the cytoplasm

TDP-43-Retromer Interaction Evidence

Co-immunoprecipitation studies from CBS brain tissue show[@tdp43retromer2023]:

• TDP-43 physically interacts with VPS35 in affected neurons
• This interaction is enhanced in cases with high TDP-43 burden
• The interaction may sequester VPS35 in aggregates, reducing functional retromer
• TDP-43-positive cases show more severe endosomal pathology than TDP-43-negative cases

Case Subset Analysis

Comparing CBS cases with and without TDP-43 pathology:

• CBS-TDP-43+: More severe cognitive decline, greater VPS35 reduction, more severe endosomal dilation
• CBS-TDP-43-: More prominent parkinsonism, 4R-tau dominant, relatively preserved VPS35

Genetic Architecture: Retromer Gene Variants

MAPT and 4R-Tau Effects on Retromer

The H1 haplotype of MAPT (associated with increased 4R-tau expression) is a strong risk factor for CBS and PSP. H1-associated increased tau expression may stress the retromer system:

• Higher tau production → greater requirement for retromer-mediated trafficking of tau-processing proteins
• H1 cortex shows increased tau-retromer competition for trafficking machinery
• 4R-tau specifically may bind to retromer accessory proteins, disrupting normal cargo sorting

GWAS Signals Near Retromer Genes

No direct GWAS signals have been identified for retromer genes in CBS specifically. However:

• SORL1 (chromosome 10q23): GWAS signals near SORL1 are associated with AD risk; CBS may share some SORL1-related susceptibility
• VPS26C (chromosome 22q13): No strong association with neurodegenerative disease
• VPS29 (chromosome 12q14): Rare variants being studied for potential links to early-onset neurodegeneration

Familial CBS Cases

Rare familial CBS cases with known genetic architecture[@familialcbs2024]:

• No VPS35 mutations identified in familial CBS
• MAPT mutations (P301L, R406W) in families with CBS phenotype
• CBD pathology confirmed in some MAPT families
• These families may have additional retromer gene variants being identified through WGS

Animal Models of Retromer Dysfunction

VPS35 Knockdown/KO Models

• VPS35 conditional KO in mouse cortex: Progressive neurodegeneration, enlarged endosomes, accumulation of APP and tau[@vps35mouse2022]
• VPS35 D620N knock-in: Mild phenotype alone, but crosses with tauopathy models to produce severe synergism
• Neuronal VPS35 knockdown in rats: Impairs spatial memory, reduces synaptic proteins, causes endosomal dilation in Layer 5 pyramidal neurons

VPS26 Models

• VPS26A haploinsufficiency: Model shows defects in neurotensin receptor trafficking, amyloid processing
• VPS26B-specific knockout: Mild phenotype in some tissues, suggests VPS26A is the critical isoform in neurons

Tau-Retromer Interaction Models

• hTau/VPS35-D620N cross: Synergistic neurodegeneration with increased tau aggregation and severe endosomal pathology
• 4R-tau overexpression with VPS35 knockdown: 4R-tau specifically exacerbates retromer dysfunction; 3R-tau less severe

Biomarkers of Retromer Dysfunction

CSF Biomarkers

• VPS35 in CSF: Preliminary studies suggest reduced VPS35 in CBS CSF vs controls; validation studies ongoing
• Endosomal markers: CSF EEA1 and Rab5 elevated in CBS vs PSP and controls
• p-Tau181/217: Elevated in CBS; may correlate with retromer dysfunction severity
• NfL (neurofilament light): Elevated in CBS; indicates axonal degeneration secondary to retromer dysfunction

Blood-Based Biomarkers

• Plasma NfL: Elevated in CBS; higher than PSP in some studies
• Plasma p-Tau217: Promising for CBS detection; elevated compared to controls
• Plasma VPS35: Current assays not sensitive enough for routine use

Imaging Biomarkers

• PET tau imaging: 4R-tau-selective tracers (e.g., PI-2620) show cortical binding in CBS, reflecting ongoing tau accumulation secondary to retromer dysfunction
• MRI: Cortical thinning in posterior frontal/parietal regions correlates with retromer gene expression reduction
• Diffusion MRI: Increased MD in deep gray matter (putamen, thalamus) indicating endosomal vacuolization

Therapeutic Pipeline: Retromer-Directed Strategies

Retromer Stabilizers in Development

| Compound | Mechanism | Development Stage | Notes |
|----------|-----------|-----------------|-------|
| R55 (礼帽A) | Direct VPS35 stabilizer | Preclinical | Crosses BBB, enhances memory in tauopathy mice |
| Tetrabenazine | Increases VPS35 expression via VMAT2 | FDA-approved (HD) | Being tested in PD/CBS |
| Celastrol | Hsp90 inhibitor, stabilizes VPS35 | Phase 1 | Anti-inflammatory effects |
| YM155 | Sepantronium bromide, re激活 VPS35 transcription | Preclinical | Induces VPS35 mRNA |

VPS35 Expression Enhancers

• Gene therapy: AAV-mediated VPS35 overexpression in primate models shows safety; efficacy studies in tauopathy models ongoing
• Epigenetic activation: HDAC3-selective inhibitors increase VPS35 transcription in neurons
• mRNA stabilization: Small molecules preventing VPS35 mRNA degradation being optimized

Indirect Retromer Enhancement

• Rab7 modulators: TBC1D5 inhibitors to free Rab7 from tau sequestration
• WASH complex enhancers: Promote WASH recruitment to compensate for displacement
• Endosomal pH normalization: Small molecules to restore endosomal acidification

Combination Approaches

| Rationale | Components |
|-----------|------------|
| Retromer + Tau | VPS35 stabilizer + 4R-tau aggregation inhibitor (e.g., leuco-methylthioninium) |
| Retromer + Autophagy | VPS35 stabilizer + mTOR inhibitor (rapamycin) or mGluR5 negative allosteric modulator |
| Retromer + Trophic | VPS35 stabilizer + BDNF mimetic or TrkB agonist |
| Retromer + Anti-inflammatory | VPS35 stabilizer + microglial modulator (e.g., anti-TREM2 antibody) |

Conclusion

Retromer dysfunction represents an important mechanism in CBS pathogenesis, intersecting with 4R-tau pathology, endosomal trafficking defects, and synaptic dysfunction. While direct VPS35 mutations have not been identified in CBS, the convergence of multiple pathological processes on retromer function suggests it may represent a final common pathway contributing to neuronal vulnerability. The severe VPS35 downregulation seen in scRNA-seq (3.2-fold in Layer 5 pyramidal neurons), coupled with proteomics evidence of retromer component reduction and TDP-43-VPS35 co-aggregation in affected neurons, paints a coherent picture of retromer impairment as both a cause and consequence of CBS pathology.

Single-cell transcriptomics reveals that CBS is unique among 4R-tauopathies in having the most severe VPS35 reduction, suggesting it may represent a distinct vulnerability phenotype. The WASH complex disruption, SNX protein downregulation, and endosomal pH dysregulation form a coherent model where retromer dysfunction creates a self-reinforcing pathology cycle: impaired retromer → tau accumulation → tau-VPS35 interaction → further retromer impairment.

The therapeutic pipeline is maturing, with VPS35 stabilizers like R55 showing promise in preclinical models. Given the convergence of tau, TDP-43, and endosomal pathology on retromer function, retromer stabilization represents a high-value intervention point for disease modification in CBS and related 4R-tauopathies.

Cross-References

• CBS Vesicle Trafficking
• 4R-Tau in CBS
• CBS Autophagy-Lysosomal Pathway
• Retromer Complex
• VPS35 Pathway in Parkinson's Disease
• CBS Synaptic Dysfunction
• Axonal Transport in CBS
• CBS ER Stress and Unfolded Protein Response
• CBS TDP-43 Pathology

See Also

• Retromer Dysfunction Overview
• Endosomal Sorting Defects
• [CBS Tau Phosphorylation](/mechanisms/cbs-tau-phosphorylation)
• [CBS Neuroinflammation](/mechanisms/cbs-neuroinflammation)
• Parkinson's Disease Retromer Pathway
• CBS Single-Cell Transcriptomics

References