GO:1904930 amphisome membrane: Components, Assembly and Research Methods
Research-grade guide for scientists and biopharma professionals
Key Takeaways
• GO:1904930 (amphisome membrane) is a cellular component defined as any membrane that is part of an amphisome, a hybrid organelle formed by the fusion of autophagosomes with endosomes or multivesicular bodies.
• Amphisomes are intermediate compartments in the autophagic pathway that can fuse with lysosomes for degradation or with the plasma membrane for secretion, thereby influencing both degradative and secretory processes.
• The amphisome membrane is compositionally distinct, containing markers of both autophagosomes (e.g., LC3) and endosomes (e.g., CD63, Rab7), and is a site for the recruitment of machinery that regulates fusion and cargo sorting.
• Amphisome membrane dynamics are implicated in viral egress, including hepatitis B virus production and release, and in specialized secretion processes such as mast cell granule fusion and exosome release.
• Dysregulation of amphisome formation and membrane function is linked to cancer, neurodegeneration, and infectious diseases, making it a potential therapeutic target.
• Research on amphisome membrane requires advanced methods such as live-cell imaging, proteomics, and CRISPR-based gene editing to dissect its molecular composition and regulation.
Description
The amphisome membrane (GO:1904930) is a cellular component defined as any membrane that is part of an amphisome, a hybrid organelle generated by the fusion of autophagosomes with endosomes or multivesicular bodies (MVBs). This membrane serves as a critical platform for the convergence of autophagic and endosomal trafficking pathways, influencing whether cargo is degraded or secreted. Understanding the amphisome membrane is essential because it represents a key decision point in cellular homeostasis, with roles in nutrient sensing, immune response, and disease pathogenesis. Recent studies have highlighted the amphisome membrane as a site for viral assembly and egress, particularly for hepatitis B virus (HBV), and for specialized secretion events such as exosome release from mast cells. Moreover, the composition and dynamics of this membrane are regulated by a complex interplay of Rab GTPases, SNAREs, and autophagy-related proteins, which are frequently altered in cancer and neurodegenerative disorders. As a result, the amphisome membrane has emerged as a focal point for researchers aiming to manipulate autophagy and endosomal trafficking for therapeutic benefit.
amphisome membrane At A Glance
| GO ID | GO:1904930 |
|---|---|
| GO term | amphisome membrane |
| Ontology | cellular_component |
| Synonym | None |
| Major function | Membrane component of amphisomes, involved in autophagosome-endosome fusion, cargo sorting, and secretion |
| Related cellular component | Amphisome (GO:0034274), autophagosome membrane (GO:0000421), endosome membrane (GO:0010008) |
| Related biological process | Autophagosome maturation (GO:0006997), endosomal transport (GO:0016197), exocytosis (GO:0006887) |
| Related molecular function | SNARE binding (GO:0000149), Rab GTPase binding (GO:0019903) |
| Pathophysiological relevance | Implicated in viral egress (HBV), cancer, neurodegeneration, and immune secretion |
What Is GO:1904930?
According to the Gene Ontology, GO:1904930 (amphisome membrane) refers to any membrane that is part of an amphisome. An amphisome is a hybrid organelle formed by the fusion of an autophagosome with an endosome or multivesicular body, and its membrane thus contains components derived from both autophagosomal and endosomal membranes. This definition implies that the amphisome membrane is a dynamic structure that can undergo further fusion with lysosomes or the plasma membrane, and it serves as a scaffold for various protein complexes involved in membrane trafficking and cargo selection.
Why Is amphisome membrane Important in Cell Biology?
The amphisome membrane is important because it represents a central hub where autophagic and endosomal pathways intersect, determining the fate of cellular cargo and influencing processes ranging from nutrient recycling to immune surveillance. Dysregulation of amphisome membrane dynamics contributes to a variety of human diseases, including cancer, neurodegenerative disorders, and viral infections. For example, the amphisome membrane is exploited by hepatitis B virus for assembly and release, and its components are altered in cancer cells to promote survival and metastasis. Therefore, studying the amphisome membrane not only advances our understanding of fundamental cell biology but also offers potential targets for therapeutic intervention.
• Acts as a convergence point for autophagic and endosomal trafficking, influencing cargo degradation versus secretion.
• Serves as a platform for viral assembly and egress, notably for hepatitis B virus.
• Participates in specialized secretion processes, such as mast cell granule fusion and exosome release.
• Its dysfunction is linked to cancer progression, including altered autophagy and exosome-mediated communication.
• Implicated in neurodegenerative diseases where autophagic flux is impaired.
• Contains unique lipid and protein composition that can be targeted for drug discovery.
• Regulated by key signaling pathways such as mTOR and Rab GTPases.
• Provides a model for studying membrane fusion and organelle identity.
• Involved in immune responses through antigen presentation and cytokine secretion.
• Offers potential biomarkers for diseases with altered autophagy.
What Happens During amphisome membrane?
Formation of the amphisome membrane
In simple terms: The amphisome membrane forms when an autophagosome fuses with an endosome or multivesicular body.
The amphisome membrane is generated through the fusion of an autophagosome with an endosome or multivesicular body (MVB). This fusion event requires the coordinated action of Rab GTPases, SNARE proteins, and tethering factors. Specifically, Rab7 on late endosomes and autophagosomes, along with its effector proteins, facilitates the tethering and fusion of these organelles. The resulting amphisome membrane contains a mix of autophagosomal markers such as LC3 and endosomal markers such as CD63 and Rab7. This hybrid membrane is a key intermediate in the autophagic pathway, capable of either fusing with lysosomes for degradation or with the plasma membrane for secretion.
Maturation and cargo sorting at the amphisome membrane
In simple terms: Once formed, the amphisome membrane helps sort cargo for degradation or release.
After formation, the amphisome membrane undergoes maturation, during which cargo is sorted for either lysosomal degradation or extracellular release. This process involves the recruitment of ESCRT components and the formation of intraluminal vesicles (ILVs) within the amphisome, similar to MVB biogenesis. The membrane also interacts with the retromer complex, which can recycle receptors back to the trans-Golgi network, as shown by the capture of retromer-TBC1D5 by autophagy. The composition of the amphisome membrane is dynamic and influenced by the availability of nutrients and cellular stress, with mTORC1 signaling playing a regulatory role.
Fusion of the amphisome membrane with lysosomes or plasma membrane
In simple terms: The amphisome membrane can fuse with lysosomes to degrade contents or with the plasma membrane to release contents.
The amphisome membrane can follow two major fates: fusion with lysosomes to form autolysosomes for degradation, or fusion with the plasma membrane for secretion. Lysosomal fusion requires the SNARE complex, including VAMP7/8 and syntaxin 17, and is regulated by Rab7 and its effectors. Alternatively, fusion with the plasma membrane leads to the release of exosomes and other cargo, a process observed in mast cells where secretory granules fuse with amphisomes to coordinate homotypic fusion and exosome release. In the context of hepatitis B virus, the amphisome membrane is utilized for viral assembly and egress through the endosomal and autophagic pathways.
Regulation of amphisome membrane dynamics
In simple terms: The behavior of the amphisome membrane is controlled by cellular signals and proteins.
The dynamics of the amphisome membrane are tightly regulated by signaling pathways, particularly mTORC1, which inhibits autophagy initiation and affects amphisome formation. Additionally, Rab GTPases such as Rab7, Rab11, and Rab33 are critical for the trafficking and fusion steps involving the amphisome membrane. The retromer complex and its associated proteins, such as TBC1D5, are also captured by autophagy, influencing receptor recycling and amphisome membrane composition. Furthermore, presynaptic autophagy-related processes involve amphisome-like structures, indicating specialized regulation in neurons.
Molecular composition of the amphisome membrane
In simple terms: The amphisome membrane contains a unique mix of proteins and lipids from both autophagosomes and endosomes.
The amphisome membrane is characterized by the presence of both autophagosomal and endosomal proteins. Key markers include LC3 (MAP1LC3B), which is lipidated and associated with the autophagosomal membrane, and CD63, a tetraspanin enriched in endosomal and exosomal membranes. Other proteins include Rab7, which is essential for fusion, and SNARE proteins such as VAMP7 and syntaxin 17. Proteomic analyses of exosomes have revealed that amphisome-derived vesicles contain a distinct set of proteins compared to other exosomes, including components of the ESCRT machinery and autophagy-related proteins. The lipid composition of the amphisome membrane is also unique, with enrichment in cholesterol and sphingolipids, which may facilitate membrane fusion events.
Key Genes Involved in GO:1904930 amphisome membrane
The following genes and proteins are key players in the formation, regulation, and function of the amphisome membrane, as supported by published literature.
| Gene | Major Role | Research Relevance |
|---|---|---|
| MAP1LC3B | Autophagosomal marker; lipidated form associates with amphisome membrane | Used as a marker for autophagosomes and amphisomes; knockout affects autophagic flux |
| CD63 | Tetraspanin enriched in endosomal and exosomal membranes; marker of amphisome membrane | Common marker for exosomes and amphisomes; knockdown alters exosome composition |
| RAB7A | Late endosomal GTPase; required for autophagosome-endosome fusion | Knockout inhibits amphisome formation; mutations linked to neuropathy |
| VAMP7 | SNARE protein mediating fusion of amphisomes with lysosomes | Knockdown impairs autophagic degradation; involved in exocytosis |
| STX17 | Autophagosomal SNARE; mediates fusion with lysosomes | Essential for autolysosome formation; mutations affect autophagy |
| TBC1D5 | Rab GAP; interacts with retromer; captured by autophagy | Regulates receptor recycling; knockout affects amphisome membrane composition |
| VPS35 | Retromer component; involved in endosomal sorting | Knockdown alters cargo sorting to amphisomes; linked to neurodegeneration |
| ESCRT-0 (HGS) | Recognizes ubiquitinated cargo for MVB sorting | Knockout affects intraluminal vesicle formation in amphisomes |
| ESCRT-III (CHMP4B) | Mediates membrane scission for ILV formation | Knockdown impairs amphisome maturation and exosome release |
| RAB11A | Recycling endosome GTPase; involved in amphisome secretion | Knockout affects exosome release from amphisomes |
| RAB27A | Regulates secretory granule fusion with amphisomes in mast cells | Knockout impairs exosome release; linked to Griscelli syndrome |
| SNARE complex (SNAP29) | Mediates membrane fusion events | Knockdown inhibits amphisome-lysosome fusion |
| ATG5 | Essential for autophagosome formation | Knockout blocks autophagosome and amphisome formation |
| ATG7 | Essential for LC3 lipidation | Knockout impairs autophagosome and amphisome membrane formation |
| ATG9A | Transmembrane protein involved in autophagosome membrane nucleation | Knockout affects autophagosome and amphisome membrane dynamics |
| LAMP1 | Lysosomal membrane protein; marker of autolysosomes | Used to assess amphisome-lysosome fusion |
| HBV surface antigen (HBsAg) | Viral protein that utilizes amphisome membrane for egress | Knockdown reduces HBV release; model for viral egress |
| RILP | Rab7 effector; links to dynein for transport | Knockdown affects amphisome positioning and fusion |
How Is amphisome membrane Regulated?
The formation and function of the amphisome membrane are regulated by multiple signaling pathways and protein complexes. The mechanistic target of rapamycin complex 1 (mTORC1) is a master regulator of autophagy; its inhibition promotes autophagosome formation and subsequent amphisome generation. Rab GTPases, particularly Rab7, Rab11, and Rab33, control the tethering and fusion steps required for amphisome membrane dynamics. The retromer complex, which mediates endosomal recycling, is captured by autophagy through interaction with TBC1D5, thereby influencing amphisome membrane composition and cargo sorting. Additionally, in specialized cells such as neurons, presynaptic autophagy-related processes involve amphisome-like structures and are regulated by synaptic activity. These regulatory mechanisms ensure that amphisome membrane function is adapted to cellular needs and stress conditions.
amphisome membrane and Human Disease
| Gene | Disease / Biology | Potential Experimental Model |
|---|---|---|
| RAB7A | Charcot-Marie-Tooth disease type 2B; impaired amphisome fusion | Knockout HeLa cells; patient-derived fibroblasts |
| VPS35 | Parkinson's disease; retromer dysfunction affects amphisome membrane | Knock-in mice; iPSC-derived neurons |
| RAB27A | Griscelli syndrome; defective exosome release from amphisomes | Knockout mast cells; patient melanocytes |
| HBV | Hepatitis B; viral egress via amphisome membrane | HBV-infected hepatoma cells; CRISPR KO of autophagy genes |
| MAP1LC3B | Cancer; altered autophagy and exosome secretion | Knockout cancer cell lines; xenograft models |
Amphisome membrane in viral infection and egress
The amphisome membrane plays a critical role in the life cycle of hepatitis B virus (HBV). HBV exploits the endosomal and autophagic pathways to assemble and release viral particles, utilizing the amphisome membrane as a platform for viral egress. Studies have shown that inhibition of amphisome formation reduces HBV production and release, suggesting that the amphisome membrane is a potential target for antiviral therapy. The interaction between HBV surface antigens and amphisome membrane components facilitates the envelopment and secretion of virions.
Amphisome membrane in cancer
In cancer, altered autophagy and endosomal trafficking contribute to tumor progression and drug resistance. The amphisome membrane is involved in the secretion of exosomes that carry oncogenic proteins and microRNAs, promoting intercellular communication within the tumor microenvironment. Dysregulation of amphisome membrane proteins, such as Rab7 and ESCRT components, has been observed in various cancers and is associated with poor prognosis. Targeting the amphisome membrane pathway may enhance the efficacy of chemotherapy by blocking pro-survival autophagic flux and exosome-mediated drug efflux.
Amphisome membrane in neurodegeneration
Neurodegenerative diseases such as Alzheimer's and Parkinson's are characterized by impaired autophagic flux and accumulation of toxic protein aggregates. The amphisome membrane is a key intermediate in the autophagic pathway, and its dysfunction can lead to the accumulation of undegraded cargo. Mutations in genes encoding amphisome membrane proteins, such as Rab7 and retromer components, have been linked to hereditary spastic paraplegia and Parkinson's disease. Enhancing amphisome membrane function may promote the clearance of aggregates and protect against neurodegeneration.
Amphisome membrane in immune secretion
Mast cells utilize amphisome membranes for the coordinated release of exosomes and secretory granules. The fusion of secretory granules with amphisomes requires Rab27A and SNARE proteins, and this process is essential for immune responses such as allergic reactions. Defects in amphisome membrane fusion can lead to impaired exosome release and altered immune signaling, as seen in Griscelli syndrome where Rab27A is mutated. Understanding the role of the amphisome membrane in immune cells may provide insights into inflammatory diseases.
From amphisome membrane-Related Genes to Experimental Models
| Research Question | Suitable Model |
|---|---|
| Does gene X regulate amphisome membrane formation? | CRISPR knockout of gene X in HeLa or HEK293T cells followed by imaging of LC3 and CD63 colocalization |
| Does a point mutation in gene Y affect amphisome membrane fusion? | CRISPR point mutation knock-in of the mutation in cell lines; assess autophagic flux and exosome release |
| How does tagging gene Z with a fluorescent protein affect amphisome membrane dynamics? | CRISPR knock-in of GFP or mCherry tag at the endogenous locus; live-cell imaging |
| What is the effect of overexpressing gene W on amphisome membrane composition? | Lentiviral overexpression of gene W; proteomic analysis of isolated amphisomes |
| Which genes are essential for amphisome membrane function? | Genome-wide CRISPR library screening with a reporter of autophagic flux |
| How does a disease-associated mutation in gene V alter amphisome membrane trafficking? | CRISPR knock-in of the mutation in patient-derived iPSCs; differentiate to relevant cell type |
How to Study the amphisome membrane Process
| Method | What It Measures | Typical Application |
|---|---|---|
| Confocal immunofluorescence | Colocalization of LC3 and CD63 | Detection of amphisome formation in cells |
| Live-cell imaging | Dynamics of fluorescently tagged amphisome proteins | Tracking fusion events and movement |
| Electron microscopy | Ultrastructure of amphisomes | Visualization of double-membrane and ILVs |
| Mass spectrometry | Protein composition of isolated amphisomes | Identification of novel membrane components |
| Western blot | Levels of LC3-II, CD63, Rab7 | Validation of amphisome enrichment |
| CRISPR knockout | Loss-of-function of candidate genes | Determining necessity for amphisome membrane function |
| CRISPR knock-in | Tagged or mutant protein expression | Studying localization and disease mutations |
| Exosome release assay | CD63-positive particle secretion | Assessing amphisome-mediated secretion |
Imaging-based methods for studying the amphisome membrane
Fluorescence microscopy, including confocal and super-resolution imaging, is widely used to visualize the amphisome membrane. Co-localization of autophagosomal markers (e.g., LC3) and endosomal markers (e.g., CD63, Rab7) indicates amphisome formation. Live-cell imaging with fluorescently tagged proteins allows tracking of amphisome membrane dynamics and fusion events. Electron microscopy can reveal the ultrastructure of amphisomes, including the presence of intraluminal vesicles.
Proteomic and biochemical analysis of the amphisome membrane
Isolation of amphisomes by density gradient centrifugation followed by mass spectrometry enables identification of membrane proteins. Proteomic studies have characterized exosome composition, which overlaps with amphisome-derived vesicles. Western blotting for markers such as LC3-II, CD63, and Rab7 is used to confirm amphisome membrane presence in fractions. Lipidomic analysis can reveal the unique lipid composition of the amphisome membrane.
Genetic and CRISPR-based approaches
CRISPR-Cas9 knockout of genes encoding amphisome membrane proteins (e.g., RAB7A, VAMP7) is used to assess their function in amphisome formation and fusion. Knock-in of point mutations or tags allows study of specific residues or real-time tracking. CRISPR library screening can identify novel regulators of amphisome membrane dynamics. These approaches are complemented by RNAi and overexpression studies.
Functional assays for amphisome membrane activity
Autophagic flux assays, such as LC3 turnover and tandem fluorescent LC3 (tfLC3), measure amphisome formation and maturation. Exosome release assays quantify secretion of CD63-positive vesicles. Viral egress assays using HBV-infected cells measure the role of amphisome membrane in viral release. These functional readouts are essential for linking amphisome membrane biology to cellular outcomes.
How CRISPR Can Be Used to Study GO:1904930 amphisome membrane
Knockout
CRISPR knockout of genes such as RAB7A, VAMP7, or ATG5 is used to determine their essential roles in amphisome membrane formation and function. For example, RAB7A knockout inhibits autophagosome-endosome fusion, preventing amphisome formation. Knockout of ATG5 or ATG7 blocks autophagosome formation, indirectly affecting amphisomes. These models are valuable for dissecting the molecular requirements of the amphisome membrane.
Point Mutation
CRISPR point mutation knock-in allows the study of specific amino acid changes in amphisome membrane proteins, such as those found in patients with Charcot-Marie-Tooth disease (RAB7A mutations) or Parkinson's disease (VPS35 mutations). These models help elucidate how disease-associated mutations affect membrane fusion, cargo sorting, and autophagic flux.
Knock-in
Knock-in of fluorescent tags (e.g., GFP, mCherry) at endogenous loci enables real-time visualization of amphisome membrane proteins in live cells. Tagging LC3, CD63, or Rab7 allows tracking of amphisome formation and dynamics without overexpression artifacts. Knock-in of disease-relevant mutations in iPSCs provides patient-specific models for studying amphisome membrane dysfunction.
Overexpression
Overexpression of wild-type or mutant amphisome membrane proteins (e.g., Rab7, VPS35) can reveal dominant effects on membrane trafficking and exosome release. However, overexpression may cause artifacts, so results should be validated with endogenous knock-in models. Overexpression is useful for initial screening of protein function and interactions.
How EDITGENE Supports amphisome membrane Research
Researchers studying amphisome membrane-related genes often need to determine whether a candidate gene is causally involved in amphisome formation, fusion, or secretion. This requires precise genetic manipulation to avoid confounding effects of overexpression or off-target silencing. EDITGENE provides a comprehensive suite of CRISPR-based services to create knockout, point-mutation, knock-in, and overexpression cell models, as well as library screening and bioinformatics support, enabling rigorous investigation of amphisome membrane biology.
Contact EDITGENE today to design your custom CRISPR model for amphisome membrane research.
Frequently Asked Questions About amphisome membrane
What is GO:1904930?
GO:1904930 is the Gene Ontology term for amphisome membrane, defined as any membrane that is part of an amphisome, a hybrid organelle formed by fusion of autophagosomes with endosomes or multivesicular bodies.
What is an amphisome?
An amphisome is a cellular organelle formed by the fusion of an autophagosome with an endosome or multivesicular body, serving as an intermediate in autophagic and endosomal trafficking.
What genes are involved in amphisome membrane?
Key genes include MAP1LC3B, CD63, RAB7A, VAMP7, STX17, TBC1D5, VPS35, and ESCRT components, which regulate formation, fusion, and cargo sorting.
How is the amphisome membrane formed?
It forms through the fusion of an autophagosome with an endosome or multivesicular body, requiring Rab7, SNARE proteins, and tethering factors.
What is the function of the amphisome membrane?
It serves as a platform for cargo sorting, degradation, and secretion, and can fuse with lysosomes or the plasma membrane.
Is the amphisome membrane involved in disease?
Yes, it is implicated in viral infections (e.g., hepatitis B), cancer, neurodegeneration, and immune disorders.
How can I study the amphisome membrane in the lab?
Common methods include fluorescence microscopy, proteomics, CRISPR knockout/knock-in, and functional assays for autophagy and exosome release.
What markers are used for the amphisome membrane?
LC3 (autophagosomal) and CD63 or Rab7 (endosomal) are commonly used markers.
Does the amphisome membrane play a role in exosome release?
Yes, amphisomes can fuse with the plasma membrane to release exosomes, a process observed in mast cells and other cell types.
What CRISPR services are available for amphisome membrane research?
EDITGENE offers knockout, point mutation knock-in, tagged knock-in, overexpression cell models, and CRISPR library screening for genes related to amphisome membrane biology.
Conclusion
The amphisome membrane (GO:1904930) is a dynamic cellular component that integrates autophagic and endosomal pathways, playing critical roles in degradation, secretion, and viral egress. Its unique composition and regulation make it a key area of study for understanding cellular homeostasis and disease mechanisms. Advances in CRISPR-based gene editing and imaging technologies continue to unravel the molecular details of amphisome membrane biology, offering potential therapeutic targets for cancer, neurodegeneration, and infectious diseases. EDITGENE provides essential tools and services to support this research, from custom cell models to high-throughput screening.
References
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