GO:0061910 autophagosome-endosome fusion: Mechanism, Genes, Functions and Research Methods
Research-grade guide for scientists and biopharma professionals
Key Takeaways
• GO:0061910 (autophagosome-endosome fusion) is the biological process in which an autophagosome fuses with an endosome to create an intermediate autophagic organelle called an amphisome.
• The process is coordinated by the Beclin1-binding protein UVRAG, which targets the class C Vps complex to link autophagosome maturation with endocytic trafficking.
• Syntaxin17 is a key SNARE required for autophagosome/endosome maturation, and its dysfunction is linked to methamphetamine-induced neuronal damage in mice.
• Hereditary spastic paraplegia proteins ZFYVE26/SPASTIZIN and SPG11/SPATACSIN differentially affect autophagy and endocytosis, implicating autophagosome-endosome fusion in neurodegeneration.
• ALS2/Alsin loss disturbs endolysosomal trafficking and exacerbates motor dysfunction in a SOD1-expressing mouse ALS model.
• Autophagosome maturation, including fusion with endosomes, is important for organelle clearance during human erythroblast differentiation and reticulocyte maturation.
Description
Autophagosome-endosome fusion (GO:0061910) is a defined biological process in which an autophagosome fuses with an endosome to create an intermediate autophagic organelle called an amphisome. This step sits at the intersection of macroautophagy and the endocytic pathway, and it is required for the normal maturation and clearance of autophagic cargo. Researchers study this process because defects in autophagosome maturation are increasingly linked to neurological disease, impaired organelle turnover, and altered cellular trafficking.
autophagosome-endosome fusion At A Glance
| GO ID | GO:0061910 |
|---|---|
| GO term | autophagosome-endosome fusion |
| Ontology | biological_process |
| Synonym | None listed |
| Major function | Fusion of an autophagosome with an endosome to form an amphisome |
| Key regulator | UVRAG, which targets the class C Vps complex |
| Related machinery | Syntaxin17-dependent autophagosome/endosome maturation |
| Disease relevance | Neurodegeneration, hereditary spastic paraplegia, ALS models |
What Is GO:0061910?
GO:0061910 describes the process in which an autophagosome fuses with an endosome to create an intermediate autophagic organelle called an amphisome. It is a biological_process term, and no synonyms are listed in QuickGO. The amphisome is an intermediate organelle that forms when autophagic and endocytic compartments meet.
Why Is autophagosome-endosome fusion Important in Cell Biology?
Autophagosome-endosome fusion is important because it links autophagic degradation with endocytic trafficking, and disruption of this step can impair autophagosome maturation and cargo clearance. Genetic evidence from hereditary spastic paraplegia and ALS models shows that proteins controlling autophagy and endocytosis can cause or modify neurological disease when mutated or lost. In addition, autophagosome maturation contributes to organelle clearance during human erythroblast differentiation and reticulocyte maturation.
• Defines the formation of the amphisome, an intermediate organelle between autophagosomes and endosomes.
• Connects macroautophagy with endocytic trafficking through UVRAG and the class C Vps complex.
• Requires Syntaxin17 for autophagosome/endosome maturation, and its disruption is linked to methamphetamine-induced neuronal damage in mice.
• Is affected differently by ZFYVE26/SPASTIZIN and SPG11/SPATACSIN mutations in hereditary spastic paraplegia types AR-SPG15 and AR-SPG11.
• Is disturbed by loss of ALS2/Alsin in a SOD1-expressing mouse ALS model, exacerbating motor dysfunction.
• Supports organelle clearance during human erythroblast differentiation, with evidence for ATG4 paralogs in autophagosome maturation.
• Contributes to reticulocyte maturation through autophagy and the endosome/exosome pathway.
• Is relevant to organelle crosstalk regulation in diseases, tumors, and regulatory T cells.
• Provides a mechanistic target for studying autophagosome maturation defects in disease models.
• Can be modeled with CRISPR knockout, point mutation, knock-in, and overexpression approaches in relevant cell types.
What Happens During autophagosome-endosome fusion?
Autophagosome and endosome recognition
In simple terms: The autophagosome and endosome must find each other before they can fuse.
Autophagosome-endosome fusion begins when an autophagosome and an endosome are brought into proximity so that they can form an amphisome. UVRAG, a Beclin1-binding protein, targets the class C Vps complex to coordinate autophagosome maturation and endocytic trafficking, which supports this recognition and fusion step.
UVRAG and class C Vps complex coordination
In simple terms: A protein called UVRAG helps organize the fusion machinery.
UVRAG binds Beclin1 and targets the class C Vps complex, linking autophagosome maturation with endocytic trafficking. This coordination is required for the normal progression of autophagosome-endosome fusion and the formation of the amphisome.
Syntaxin17-dependent maturation
In simple terms: Syntaxin17 is a SNARE protein that helps the autophagosome and endosome mature and fuse.
Syntaxin17 plays key roles in autophagosome/endosome maturation, and its dysfunction is associated with methamphetamine-induced neuronal damage in mice. This places Syntaxin17 as a central component of the maturation step that leads to autophagosome-endosome fusion.
Amphisome formation
In simple terms: The fused intermediate is called an amphisome.
The process defined by GO:0061910 creates an intermediate autophagic organelle called an amphisome. Amphisome formation represents the physical outcome of autophagosome-endosome fusion and is a key intermediate in autophagic and endocytic crosstalk.
Crosstalk with organelle clearance and differentiation
In simple terms: This fusion step helps cells clear organelles and mature.
Autophagy facilitates organelle clearance during differentiation of human erythroblasts, with evidence for a role for ATG4 paralogs during autophagosome maturation. Autophagosome maturation also contributes to human reticulocyte maturation through autophagy and the endosome/exosome pathway.
Key Genes Involved in GO:0061910 autophagosome-endosome fusion
The following genes and proteins have been experimentally linked to autophagosome-endosome fusion, autophagosome maturation, or related endocytic trafficking in the cited literature.
| Gene | Major Role | Research Relevance |
|---|---|---|
| UVRAG | Beclin1-binding protein that targets the class C Vps complex to coordinate autophagosome maturation and endocytic trafficking | Central regulator of autophagosome-endosome fusion and amphisome formation |
| BECN1 (Beclin1) | Binding partner of UVRAG in the coordination of autophagosome maturation | Chaperone-mediated autophagy promotes Beclin1 degradation in persistently infected hepatitis C virus cell culture |
| STX17 (Syntaxin17) | Key role in autophagosome/endosome maturation | Linked to methamphetamine-induced neuronal damage in mice |
| ZFYVE26 (SPASTIZIN) | Affects autophagy and endocytosis in hereditary spastic paraplegia type AR-SPG15 | Disease-relevant regulator of autophagy and endocytosis |
| SPG11 (SPATACSIN) | Affects autophagy and endocytosis in hereditary spastic paraplegia type AR-SPG11 | Disease-relevant regulator of autophagy and endocytosis |
| ALS2 (Alsin) | Endolysosomal trafficking protein whose loss disturbs trafficking | Loss exacerbates motor dysfunction in a SOD1-expressing mouse ALS model |
| ATG4 paralogs | Role during autophagosome maturation | Implicated in organelle clearance during human erythroblast differentiation |
| Class C Vps complex | Targeted by UVRAG to coordinate autophagosome maturation and endocytic trafficking | Core machinery for autophagosome-endosome fusion |
| Organelle crosstalk regulators | Regulated in diseases, tumors, and regulatory T cells | Novel classification of organelle crosstalk regulators |
| Endosome/exosome pathway components | Participate in reticulocyte maturation | Relevant to human reticulocyte maturation |
| Autophagosome maturation machinery | Required for autophagosome maturation | Studied in erythroblast differentiation |
| Endocytic trafficking machinery | Coordinates with autophagosome maturation | Studied through UVRAG and class C Vps complex |
| SNARE-mediated fusion machinery | Includes Syntaxin17 in autophagosome/endosome maturation | Target for neuronal damage studies |
| Hereditary spastic paraplegia proteins | ZFYVE26/SPASTIZIN and SPG11/SPATACSIN affect autophagy and endocytosis | Models for AR-SPG15 and AR-SPG11 |
| SOD1 | Expressed in a mouse ALS model where ALS2/Alsin loss exacerbates motor dysfunction | Used to study endolysosomal trafficking in ALS |
| Beclin1-UVRAG complex | Coordinates autophagosome maturation and endocytic trafficking | Target for mechanistic studies of amphisome formation |
How Is autophagosome-endosome fusion Regulated?
Autophagosome-endosome fusion is regulated by UVRAG, which binds Beclin1 and targets the class C Vps complex to coordinate autophagosome maturation and endocytic trafficking. Syntaxin17 is required for autophagosome/endosome maturation, and its dysfunction is linked to methamphetamine-induced neuronal damage in mice. In addition, chaperone-mediated autophagy promotes Beclin1 degradation in persistently infected hepatitis C virus cell culture, providing a mechanism that can influence Beclin1-dependent processes. Organelle crosstalk regulators are also regulated in diseases, tumors, and regulatory T cells, indicating broader regulatory layers.
autophagosome-endosome fusion and Human Disease
| Gene | Disease / Biology | Potential Experimental Model |
|---|---|---|
| STX17 | Methamphetamine-induced neuronal damage in mice | Neuronal cell knockout or point-mutation models |
| ZFYVE26 | Hereditary spastic paraplegia type AR-SPG15 | Patient-derived or knockout cell models |
| SPG11 | Hereditary spastic paraplegia type AR-SPG11 | Patient-derived or knockout cell models |
| ALS2 | ALS-related motor dysfunction in a SOD1-expressing mouse model | ALS2 knockout in SOD1-expressing models |
| BECN1 | Hepatitis C virus persistence and Beclin1 degradation | HCV cell culture models with chaperone-mediated autophagy modulation |
Neurodegeneration and neuronal damage
Syntaxin17-mediated autophagosome/endosome maturation is important in methamphetamine-induced neuronal damage in mice, linking this fusion process to neuronal injury. Loss of ALS2/Alsin disturbs endolysosomal trafficking and exacerbates motor dysfunction in a SOD1-expressing mouse ALS model.
Hereditary spastic paraplegia
ZFYVE26/SPASTIZIN and SPG11/SPATACSIN mutations in hereditary spastic paraplegia types AR-SPG15 and AR-SPG11 have different effects on autophagy and endocytosis, implicating autophagosome-endosome fusion-related pathways in disease.
Viral infection and Beclin1 regulation
Chaperone-mediated autophagy promotes Beclin1 degradation in persistently infected hepatitis C virus cell culture, which can affect Beclin1-dependent processes relevant to autophagosome maturation.
Erythroid differentiation and reticulocyte maturation
Autophagy facilitates organelle clearance during differentiation of human erythroblasts, with evidence for ATG4 paralogs during autophagosome maturation. The endosome/exosome pathway is also involved in human reticulocyte maturation.
From autophagosome-endosome fusion-Related Genes to Experimental Models
| Research Question | Suitable Model |
|---|---|
| Does loss of Syntaxin17 impair autophagosome-endosome fusion? | STX17 knockout neuronal cells |
| Do ZFYVE26 or SPG11 mutations differentially affect autophagy and endocytosis? | Knockout or point-mutation cells for ZFYVE26 and SPG11 |
| Does ALS2 loss disturb endolysosomal trafficking in ALS? | ALS2 knockout in SOD1-expressing mouse or cell models |
| Is UVRAG required for amphisome formation? | UVRAG knockout or tagged knock-in cells |
| Do ATG4 paralogs regulate autophagosome maturation during erythroblast differentiation? | ATG4 knockout or overexpression in erythroblast models |
| How does Beclin1 degradation affect autophagosome maturation? | BECN1 point-mutation or knockout in HCV cell culture |
How to Study the autophagosome-endosome fusion Process
| Method | What It Measures | Typical Application |
|---|---|---|
| Fluorescence microscopy | Autophagosome and endosome localization and amphisome formation | Visualizing autophagosome-endosome fusion |
| Electron microscopy | Ultrastructure of autophagic and endocytic compartments | Confirming amphisome intermediates |
| Knockout models | Loss-of-function effects on autophagy and endocytosis | Testing causal roles of ZFYVE26, SPG11, ALS2 |
| Point-mutation models | Effects of disease-associated mutations | Modeling AR-SPG15 and AR-SPG11 |
| Overexpression models | Gain-of-function effects on autophagosome maturation | Testing ATG4 paralogs in erythroblast differentiation |
| Autophagy flux assays | Autophagosome maturation and clearance | Studying organelle clearance during differentiation |
| Endocytic trafficking assays | Endosome function and trafficking | Evaluating ALS2/Alsin loss in ALS models |
| Beclin1 degradation assays | Beclin1 protein stability | Studying chaperone-mediated autophagy in HCV cell culture |
Imaging of autophagosome-endosome fusion
Fluorescence and electron microscopy can be used to visualize autophagosome and endosome compartments and the formation of amphisomes, as described in studies of autophagosome maturation and endocytic trafficking. Imaging in neuronal cells can reveal defects associated with Syntaxin17 dysfunction.
Genetic perturbation and phenotypic assays
Knockout, point-mutation, and overexpression models can be used to test the roles of UVRAG, Syntaxin17, ZFYVE26, SPG11, and ALS2 in autophagy and endocytosis. These approaches help determine whether a candidate gene is causally involved in autophagosome-endosome fusion.
Autophagy and endocytosis flux assays
Autophagy and endocytosis can be assessed in cells carrying disease-relevant mutations, as shown for ZFYVE26/SPASTIZIN and SPG11/SPATACSIN in hereditary spastic paraplegia models. Such assays can be combined with endolysosomal trafficking readouts in ALS2 models.
Differentiation and organelle clearance studies
Erythroblast differentiation and reticulocyte maturation provide physiological contexts to study autophagosome maturation and organelle clearance. These systems can be used to test the contribution of ATG4 paralogs and endosome/exosome pathway components.
How CRISPR Can Be Used to Study GO:0061910 autophagosome-endosome fusion
Knockout
CRISPR knockout can be used to delete genes such as STX17, UVRAG, ZFYVE26, SPG11, or ALS2 to test their requirement for autophagosome-endosome fusion and amphisome formation. Knockout studies in neuronal or patient-derived cells can reveal defects in autophagy and endocytosis.
Point Mutation
CRISPR point mutation can introduce disease-associated variants into genes such as ZFYVE26 or SPG11 to model hereditary spastic paraplegia types AR-SPG15 and AR-SPG11 and assess their differential effects on autophagy and endocytosis. Point mutations can also be used to dissect domain-specific functions of UVRAG or Syntaxin17.
Knock-in
CRISPR knock-in can add tags or reporters to genes such as UVRAG, STX17, or ATG4 paralogs to track protein localization and dynamics during autophagosome-endosome fusion. Tagged knock-in models enable imaging of amphisome formation in live cells.
Overexpression
CRISPR overexpression can be used to elevate genes such as ATG4 paralogs or UVRAG to test gain-of-function effects on autophagosome maturation and organelle clearance. Overexpression in erythroblast or neuronal models can complement knockout phenotypes.
How EDITGENE Supports autophagosome-endosome fusion Research
Researchers studying autophagosome-endosome fusion-related genes often need to determine whether a candidate gene is causally involved in amphisome formation, autophagosome maturation, or endocytic trafficking. EDITGENE provides CRISPR-based cell model services that support these investigations with knockout, point-mutation, knock-in, overexpression, library screening, and bioinformatics workflows.
Contact EDITGENE today to design your custom CRISPR model for autophagosome-endosome fusion research.
Frequently Asked Questions About autophagosome-endosome fusion
What is autophagosome-endosome fusion?
Autophagosome-endosome fusion (GO:0061910) is the process in which an autophagosome fuses with an endosome to create an intermediate autophagic organelle called an amphisome.
What is the GO ID for autophagosome-endosome fusion?
The GO ID is GO:0061910, and the ontology aspect is biological_process.
What genes are involved in autophagosome-endosome fusion?
Genes and proteins linked to this process include UVRAG, Beclin1, Syntaxin17, ZFYVE26/SPASTIZIN, SPG11/SPATACSIN, ALS2/Alsin, and ATG4 paralogs.
What is an amphisome?
An amphisome is the intermediate autophagic organelle created when an autophagosome fuses with an endosome.
How does UVRAG regulate autophagosome-endosome fusion?
UVRAG binds Beclin1 and targets the class C Vps complex to coordinate autophagosome maturation and endocytic trafficking.
What is the role of Syntaxin17 in autophagosome-endosome fusion?
Syntaxin17 has key roles in autophagosome/endosome maturation, and its dysfunction is linked to methamphetamine-induced neuronal damage in mice.
Is autophagosome-endosome fusion linked to neurodegenerative disease?
Yes, proteins such as ZFYVE26/SPASTIZIN, SPG11/SPATACSIN, and ALS2/Alsin affect autophagy and endocytosis and are linked to hereditary spastic paraplegia and ALS models.
How can I study autophagosome-endosome fusion in the lab?
Researchers use imaging, genetic perturbation, autophagy and endocytosis flux assays, and differentiation models to study this process.
What CRISPR models are useful for studying autophagosome-endosome fusion?
Knockout, point-mutation, knock-in, and overexpression models can be used to test genes such as STX17, UVRAG, ZFYVE26, SPG11, and ALS2.
Does autophagosome-endosome fusion matter for red blood cell development?
Autophagy facilitates organelle clearance during human erythroblast differentiation, and the endosome/exosome pathway is involved in reticulocyte maturation.
Conclusion
GO:0061910 (autophagosome-endosome fusion) defines the formation of the amphisome through fusion of an autophagosome with an endosome, a step coordinated by UVRAG, the class C Vps complex, and Syntaxin17. This process is relevant to neurodegeneration, hereditary spastic paraplegia, ALS models, viral infection, and erythroid differentiation. CRISPR-based knockout, point-mutation, knock-in, and overexpression models provide practical tools to dissect the causal roles of genes involved in this fusion event.
References
- 1. Wang X et al.. 2024. Key roles of autophagosome/endosome maturation mediated by Syntaxin17 in methamphetamine-induced neuronal damage in mice.. Mol Med 30(1):4 PMID: 38172666
- 2. Aydin Y et al.. 2018. Chaperone-Mediated Autophagy Promotes Beclin1 Degradation in Persistently Infected Hepatitis C Virus Cell Culture.. Am J Pathol 188(10):2339-2355 PMID: 30075149
- 3. Liu M et al.. 2021. Organelle Crosstalk Regulators Are Regulated in Diseases, Tumors, and Regulatory T Cells: Novel Classification of Organelle Crosstalk Regulators.. Front Cardiovasc Med 8:713170 PMID: 34368262
- 4. Liang C et al.. 2008. Beclin1-binding UVRAG targets the class C Vps complex to coordinate autophagosome maturation and endocytic trafficking.. Nat Cell Biol 10(7):776-87 PMID: 18552835
- 5. Vantaggiato C et al.. 2019. ZFYVE26/SPASTIZIN and SPG11/SPATACSIN mutations in hereditary spastic paraplegia types AR-SPG15 and AR-SPG11 have different effects on autophagy and endocytosis.. Autophagy 15(1):34-57 PMID: 30081747
- 6. Hadano S et al.. 2010. Loss of ALS2/Alsin exacerbates motor dysfunction in a SOD1-expressing mouse ALS model by disturbing endolysosomal trafficking.. PLoS One 5(3):e9805 PMID: 20339559
- 7. Betin VM et al.. 2013. Autophagy facilitates organelle clearance during differentiation of human erythroblasts: evidence for a role for ATG4 paralogs during autophagosome maturation.. Autophagy 9(6):881-93 PMID: 23508006
- 8. Griffiths RE et al.. 2012. The ins and outs of human reticulocyte maturation: autophagy and the endosome/exosome pathway.. Autophagy 8(7):1150-1 PMID: 22659916
