GO:0035973 aggrephagy: Selective Autophagy Pathway, Genes, Functions and Research Methods
Research-grade guide for scientists and biopharma professionals
Key Takeaways
• GO:0035973 aggrephagy is the selective degradation of protein aggregates by macroautophagy, as defined by QuickGO.
• Aggrephagy clears solid, detergent-insoluble protein aggregates that are too large for the proteasome, protecting cells from proteotoxic stress.
• The chaperone CCT2 acts as a dedicated aggrephagy receptor that recognizes solid protein aggregates and delivers them to autophagosomes.
• A chaperone-proteasome-based fragmentation machinery is required before aggregates can be efficiently engulfed by autophagosomes.
• Aggrephagy deficiency is linked to neurodegenerative disease, myopathies, and preeclampsia, making it a therapeutic target.
• CRISPR knockout, knock-in, and overexpression cell models enable causal dissection of aggrephagy genes such as CCT2 and cargo receptors.
Description
Aggrephagy (GO:0035973) is the selective degradation of protein aggregates by macroautophagy, a process that removes toxic, detergent-insoluble protein assemblies from the cytoplasm. Unlike bulk autophagy, aggrephagy specifically recognizes aggregated cargo through dedicated receptors and chaperone systems, coupling aggregate recognition to autophagosome formation. This pathway is essential for proteostasis because large solid aggregates cannot enter the narrow proteasomal channel and must be cleared by autophagy. Researchers study aggrephagy to understand how cells cope with proteotoxic stress and to identify therapeutic entry points for diseases characterized by aggregate accumulation. The pathway has emerged as a distinct selective autophagy subtype with its own receptors, regulatory logic, and disease connections.
aggrephagy At A Glance
| GO ID | GO:0035973 |
|---|---|
| GO term | aggrephagy |
| Ontology | biological_process |
| Synonym | none |
| Definition | The selective degradation of protein aggregates by macroautophagy |
| Major function | Selective clearance of solid protein aggregates through macroautophagy |
| Key receptor | CCT2, an aggrephagy receptor for solid protein aggregates |
| Required machinery | Chaperone-proteasome-based fragmentation machinery |
| Disease relevance | Neurodegeneration, myopathies, preeclampsia |
What Is GO:0035973?
Aggrephagy is the selective macroautophagic degradation of protein aggregates. In this process, aggregated proteins are recognized by specific receptors or chaperone-assisted machinery, enclosed within autophagosomes, and delivered to lysosomes for degradation. It differs from general macroautophagy because it targets aggregated cargo rather than bulk cytoplasm, and it depends on cargo recognition factors such as CCT2.
Why Is aggrephagy Important in Cell Biology?
Aggrephagy is important because it is a primary clearance route for solid protein aggregates that cannot be degraded by the proteasome, and its failure contributes to proteotoxic disease. Understanding aggrephagy provides mechanistic insight into selective autophagy and offers targets for modulating aggregate clearance in neurodegeneration, muscle disease, and placental pathology.
• Clears solid protein aggregates that are inaccessible to the proteasome.
• Defines a selective autophagy subtype with dedicated receptors such as CCT2.
• Protects neurons from aggregate-induced toxicity in Alzheimer's disease models.
• Contributes to muscle fiber proteostasis and is dysregulated in myopathies.
• Deficiency in the placenta is linked to preeclampsia pathogenesis.
• Phase separation regulates aggrephagy cargo recognition and autophagosome engagement.
• Provides a therapeutic target for enhancing aggregate clearance.
• Requires chaperone-proteasome fragmentation before autophagic engulfment.
• Can be studied with CRISPR knockout and knock-in models of receptor genes.
• Links proteostasis, autophagy, and disease in a single mechanistic framework.
What Happens During aggrephagy?
Aggregate recognition and receptor engagement
In simple terms: The cell first tags protein clumps so the autophagy machinery knows what to destroy.
Aggrephagy begins when solid protein aggregates are recognized by selective receptors. CCT2 functions as an aggrephagy receptor that binds solid protein aggregates and links them to the autophagic machinery. This recognition step distinguishes aggrephagy from bulk autophagy and ensures that only aggregated cargo is targeted.
Chaperone-proteasome-based fragmentation
In simple terms: Large clumps are first broken into smaller pieces so they can be packaged for disposal.
A chaperone-proteasome-based fragmentation machinery is essential for aggrephagy, processing large aggregates into smaller units that can be efficiently engulfed by autophagosomes. This step couples proteasomal activity to autophagic clearance and explains why proteasome and autophagy systems cooperate during aggregate removal.
Phase separation in cargo organization
In simple terms: The cell uses liquid-like droplets to organize and concentrate the material to be degraded.
Phase separation regulates aggrephagy by concentrating cargo and receptors into biomolecular condensates that facilitate autophagosome engagement. This physical mechanism helps explain how cells handle the heterogeneous nature of protein aggregates.
Autophagosome engulfment and lysosomal degradation
In simple terms: The tagged clump is wrapped in a membrane bubble and delivered to the cell's recycling center.
Once recognized and processed, aggregates are enclosed by autophagosomes and delivered to lysosomes for degradation. This final step completes the selective degradation of protein aggregates and restores proteostasis.
Key Genes Involved in GO:0035973 aggrephagy
The following genes and proteins are central to aggrephagy based on published literature.
| Gene | Major Role | Research Relevance |
|---|---|---|
| CCT2 | Aggrephagy receptor for solid protein aggregates | Core receptor; knockout and knock-in models define cargo specificity |
| CCT1 | Chaperonin subunit assisting protein folding | Supports chaperone machinery for aggregate handling |
| CCT3 | Chaperonin subunit in the CCT complex | Contributes to chaperone-proteasome fragmentation |
| CCT4 | Chaperonin subunit in the CCT complex | Required for efficient aggregate processing |
| CCT5 | Chaperonin subunit in the CCT complex | Participates in chaperone-assisted aggrephagy |
| CCT6A | Chaperonin subunit in the CCT complex | Supports folding and fragmentation of aggregates |
| CCT7 | Chaperonin subunit in the CCT complex | Involved in chaperone-dependent aggregate clearance |
| CCT8 | Chaperonin subunit in the CCT complex | Required for chaperone-proteasome fragmentation |
| MAP1LC3B | Autophagosome membrane protein | Marker of autophagosome formation during aggrephagy |
| SQSTM1 | Selective autophagy receptor | Links ubiquitinated cargo to autophagosomes |
| NBR1 | Selective autophagy receptor | Contributes to aggregate recognition |
| OPTN | Selective autophagy receptor | Participates in aggrephagy cargo recognition |
| TAX1BP1 | Selective autophagy receptor | Assists in autophagic clearance of aggregates |
| CALCOCO2 | Selective autophagy receptor | Binds ubiquitinated aggregates for autophagic degradation |
| ATG5 | Core autophagy machinery | Required for autophagosome formation in aggrephagy |
| ATG7 | Core autophagy machinery | Essential for aggrephagy in knockout studies |
| BECN1 | Autophagy initiation factor | Regulates autophagosome nucleation during aggrephagy |
How Is aggrephagy Regulated?
Aggrephagy is regulated by the core autophagy machinery and by selective receptors such as CCT2. Phase separation modulates the spatial organization of cargo and receptors, influencing the efficiency of autophagic clearance. The chaperone-proteasome fragmentation machinery also acts as a regulatory node, because its activity determines whether large aggregates become competent for autophagic engulfment. In disease contexts, aggrephagy deficiency has been linked to impaired clearance and aggregate accumulation.
aggrephagy and Human Disease
| Gene | Disease / Biology | Potential Experimental Model |
|---|---|---|
| CCT2 | Neurodegeneration and aggregate clearance failure | CCT2 knockout and knock-in cell models |
| MAP1LC3B | Autophagy flux in Alzheimer's disease | LC3B reporter knock-in for autophagosome tracking |
| SQSTM1 | Protein aggregate accumulation in myopathies | SQSTM1 knockout muscle cell models |
| ATG7 | Autophagy deficiency in preeclampsia | ATG7 knockout placental cell models |
| CCT8 | Chaperone-proteasome fragmentation defects | CCT8 knockout for aggrephagy flux assays |
Aggrephagy in Alzheimer's disease
Targeting aggrephagy has been proposed as a therapeutic strategy for Alzheimer's disease, where aggregate accumulation contributes to neuronal dysfunction. Enhancing selective autophagic clearance may reduce proteotoxic burden in affected neurons.
Aggrephagy in myopathies
Protein aggregates and aggrephagy are implicated in myopathies, where impaired clearance contributes to muscle fiber degeneration. Studying aggrephagy in muscle models may reveal mechanisms of proteostasis failure.
Aggrephagy deficiency in preeclampsia
Aggrephagy deficiency in the placenta has been proposed as a new pathogenesis mechanism for preeclampsia. This links selective autophagy failure to placental dysfunction and pregnancy complications.
From aggrephagy-Related Genes to Experimental Models
| Research Question | Suitable Model |
|---|---|
| Is CCT2 required for aggrephagy? | CCT2 knockout cell line |
| Does a disease variant impair receptor function? | Point-mutation knock-in of CCT2 |
| Where does CCT2 localize during aggrephagy? | Tagged knock-in of CCT2 |
| Does overexpression enhance aggregate clearance? | CCT2 overexpression cell model |
| Which receptors cooperate in aggrephagy? | Multiplex knockout of SQSTM1, NBR1, OPTN |
| Does fragmentation require proteasome activity? | Proteasome inhibitor treatment in knockout backgrounds |
How to Study the aggrephagy Process
| Method | What It Measures | Typical Application |
|---|---|---|
| Fluorescence microscopy | Co-localization of aggregates and autophagosomes | Visualizing aggrephagy flux |
| Autophagic flux assay | LC3 turnover and degradation | Quantifying aggrephagy activity |
| Proteomics | Composition of aggregate fractions | Identifying cargo and receptors |
| CRISPR library screening | Genes required for aggregate clearance | Discovery of aggrephagy regulators |
| Western blot | Levels of aggregate-prone proteins | Monitoring clearance efficiency |
| Immunoprecipitation | Receptor-cargo interactions | Mapping aggrephagy complexes |
| Phase separation assays | Condensate formation | Studying cargo organization |
| Knockout validation | Loss-of-function phenotypes | Testing gene necessity |
Imaging aggregate clearance
Fluorescence imaging of tagged aggregates and autophagosome markers allows direct visualization of aggrephagy flux in cells. Co-localization of CCT2 with aggregates confirms receptor engagement.
Proteomics of aggregate fractions
Proteomic analysis of detergent-insoluble fractions identifies aggregate cargo and associated aggrephagy machinery. This approach reveals which proteins depend on CCT2 for clearance.
Autophagic flux assays
LC3 turnover and tandem fluorescent reporters measure autophagic flux during aggrephagy. These assays distinguish defects in autophagosome formation from defects in lysosomal degradation.
Genetic screens for aggrephagy regulators
CRISPR library screening can identify genes required for aggregate clearance, including chaperones and receptors. Hits can be validated with focused knockout panels.
How CRISPR Can Be Used to Study GO:0035973 aggrephagy
Knockout
CRISPR knockout of CCT2 or core autophagy genes abolishes aggrephagy and causes aggregate accumulation, providing causal evidence for gene function. Knockout models are essential for distinguishing receptors from accessory factors.
Point Mutation
Point-mutation knock-in can model disease-associated variants in aggrephagy genes and test whether specific residues are required for cargo recognition. This approach links genotype to aggrephagy efficiency.
Knock-in
Tagged knock-in of CCT2 or LC3B enables real-time tracking of receptor localization and autophagosome dynamics in live cells. Knock-in reporters preserve endogenous regulation.
Overexpression
Overexpression of CCT2 or selective receptors can enhance aggregate clearance and test sufficiency in aggrephagy. Overexpression models are useful for screening therapeutic candidates.
How EDITGENE Supports aggrephagy Research
Researchers studying aggrephagy-related genes often need to determine whether a candidate gene is causally involved in aggregate clearance or merely correlated with it. CRISPR-based cell models provide the controlled genetic backgrounds required to establish causality and to dissect receptor, chaperone, and autophagy contributions.
Contact EDITGENE today to design your custom CRISPR model for aggrephagy research.
Frequently Asked Questions About aggrephagy
What is aggrephagy?
Aggrephagy is the selective degradation of protein aggregates by macroautophagy, defined as GO:0035973.
What genes are involved in aggrephagy?
Key genes include CCT2, the CCT chaperonin subunits, MAP1LC3B, SQSTM1, NBR1, OPTN, and core autophagy genes such as ATG5 and ATG7.
What is the role of CCT2 in aggrephagy?
CCT2 acts as an aggrephagy receptor that recognizes solid protein aggregates and targets them for autophagic degradation.
How is aggrephagy regulated?
Aggrephagy is regulated by selective receptors, phase separation, and a chaperone-proteasome-based fragmentation machinery.
What diseases are linked to aggrephagy?
Aggrephagy is linked to Alzheimer's disease, myopathies, and preeclampsia.
How can I study aggrephagy in the lab?
Common methods include fluorescence imaging, autophagic flux assays, proteomics, and CRISPR knockout models.
What is the GO ID for aggrephagy?
The GO ID for aggrephagy is GO:0035973.
Is aggrephagy the same as macroautophagy?
No, aggrephagy is a selective subtype of macroautophagy that specifically targets protein aggregates.
What happens when aggrephagy fails?
Failure of aggrephagy leads to accumulation of protein aggregates and is associated with proteotoxic disease.
Can CRISPR be used to study aggrephagy?
Yes, CRISPR knockout, knock-in, and overexpression models are widely used to dissect aggrephagy gene function.
Conclusion
Aggrephagy (GO:0035973) is a selective macroautophagic pathway dedicated to clearing solid protein aggregates, with CCT2 as a key receptor and a chaperone-proteasome fragmentation step as a prerequisite. Its dysfunction is linked to neurodegeneration, myopathies, and preeclampsia, making it a compelling target for therapeutic modulation. CRISPR-based cell models provide the causal tools needed to advance aggrephagy research.
References
- 1. Bauer B et al.. 2023. Aggrephagy at a glance.. J Cell Sci 136(10) PMID: 37254869
- 2. Ma X et al.. 2022. CCT2 is an aggrephagy receptor for clearance of solid protein aggregates.. Cell 185(8):1325-1345.e22 PMID: 35366418
- 3. Gibertini S et al.. 2023. Protein Aggregates and Aggrephagy in Myopathies.. Int J Mol Sci 24(9) PMID: 37176163
- 4. Malampati S et al.. 2020. Targeting Aggrephagy for the Treatment of Alzheimer's Disease.. Cells 9(2) PMID: 32012902
- 5. Sun D et al.. 2020. Phase Separation in Regulation of Aggrephagy.. J Mol Biol 432(1):160-169 PMID: 31260696
- 6. Nakashima A et al.. 2021. Aggrephagy Deficiency in the Placenta: A New Pathogenesis of Preeclampsia.. Int J Mol Sci 22(5) PMID: 33670947
- 7. Luo J et al.. 2024. The essential role of CCT2 in the regulation of aggrephagy.. Front Aging Neurosci 16:1491001 PMID: 39478698
- 8. Mauthe M et al.. 2025. A chaperone-proteasome-based fragmentation machinery is essential for aggrephagy.. Nat Cell Biol 27(9):1448-1464 PMID: 40866512
