GO:0140494 migrasome: Components, Assembly and Research Methods
Research-grade guide for scientists and biopharma professionals
Key Takeaways
• GO:0140494 migrasome is a vesicular organelle that forms on retraction fibers behind migrating cells and mediates the release of cytoplasmic contents during cell migration.
• Migrasome biogenesis depends on assembly of micron-scale tetraspanin macrodomains, especially CD9 and CD81, on retraction fibers.
• The phosphatidylinositol (4,5)-bisphosphate-Rab35 axis regulates migrasome formation, linking membrane lipid signaling to organelle assembly.
• Migrasomes function in mitochondrial quality control through mitocytosis, in cell-cell communication, and in the transfer of cytoplasmic cargo between cells.
• Migrasome research has expanded over the past decade from biogenesis to physiological functions and disease implications, including cancer and inflammation.
• Key experimental approaches include live-cell imaging of tetraspanin reporters, proteomics of purified migrasomes, and CRISPR-based perturbation of migrasome genes.
Description
The migrasome (GO:0140494) is a recently defined vesicular organelle that forms on retraction fibers behind migrating cells and mediates the release of cytoplasmic contents during cell migration. Unlike classical extracellular vesicles such as exosomes, migrasomes are spatially and temporally coupled to cell migration, arising as micron-scale structures on the thin tethers left behind by moving cells. Since their initial characterization, migrasomes have been recognized as a distinct functional extracellular vesicle with roles in intercellular communication and cargo transfer. Understanding the migrasome is important for researchers because it connects cell migration, organelle biology, and extracellular vesicle signaling in development, immunity, and disease. The organelle has been implicated in mitochondrial quality control through a process termed mitocytosis, in which damaged mitochondria are transported into migrasomes and released for degradation. As a cellular component, the migrasome provides a tractable model to study how membrane domains, cytoskeletal dynamics, and lipid signaling converge to build a specialized organelle. This article summarizes the definition, structure, molecular mechanism, key genes, disease relevance, and research methods for GO:0140494 migrasome, based on published literature.
migrasome At A Glance
| GO ID | GO:0140494 |
|---|---|
| GO term | migrasome |
| Ontology | cellular_component |
| Synonym | none listed |
| Major function | Release of cytoplasmic contents during cell migration and mediation of cell-cell communication |
| Location | Retraction fibers behind migrating cells |
| Key structural components | Tetraspanin macrodomains, especially CD9 and CD81 |
| Regulatory axis | Phosphatidylinositol (4,5)-bisphosphate-Rab35 axis |
| Associated process | Mitocytosis, a migrasome-mediated mitochondrial quality-control process |
What Is GO:0140494?
According to the Gene Ontology, GO:0140494 migrasome is a vesicular organelle that forms on retraction fibers behind migrating cells and mediates the release of cytoplasmic contents during cell migration. In other words, it is a migration-dependent extracellular vesicle-like structure that buds from retraction fibers and carries cytoplasmic cargo away from the moving cell. The term is classified under the cellular_component ontology aspect and has no listed synonyms in QuickGO.
Why Is migrasome Important in Cell Biology?
The migrasome is important because it represents a migration-dependent organelle that links cell movement to the release of cytoplasmic material, thereby influencing how cells communicate and maintain quality control of their organelles. Its discovery has expanded the field of extracellular vesicles beyond exosomes and microvesicles, providing a new mechanism for intercellular transfer of proteins, lipids, and possibly RNA. Because migrasome formation is tightly coupled to retraction fibers and tetraspanin macrodomains, it also serves as a model for studying how membrane domains and cytoskeletal structures cooperate to build organelles. Dysregulation of migrasome-related processes has been associated with cancer, inflammation, and other pathological states, making it a potential target for diagnostics and therapeutics.
• Defines a new class of extracellular vesicle that is dependent on cell migration.
• Mediates mitochondrial quality control through mitocytosis, clearing damaged mitochondria.
• Facilitates cell-cell communication by transferring cytoplasmic contents between cells.
• Provides a model for studying tetraspanin macrodomain assembly on retraction fibers.
• Links lipid signaling, specifically PI(4,5)P2 and Rab35, to organelle biogenesis.
• Has implications for cancer biology, including tumor microenvironment communication.
• May contribute to immune regulation and inflammatory responses.
• Offers a potential source of biomarkers due to its cargo content.
• Enables studies of organelle positioning and cytoskeletal remodeling during migration.
• Represents a target for CRISPR-based functional screens to identify novel regulators.
Migrasome Biology: Process, Structure, and Molecular Mechanism
What Happens During migrasome Formation?
In simple terms: When a cell moves, it leaves behind thin threads; tiny bubbles form on these threads and eventually pinch off.
Migrasome formation begins when a migrating cell extends retraction fibers, which are thin membranous tethers left behind as the cell body moves forward. On these fibers, tetraspanin proteins, particularly CD9 and CD81, assemble into micron-scale macrodomains that serve as nucleation sites for migrasome biogenesis. The phosphatidylinositol (4,5)-bisphosphate-Rab35 axis regulates this process, with Rab35 recruited to PI(4,5)P2-enriched membranes to promote migrasome formation. As the retraction fiber retracts or breaks, the migrasome is released into the extracellular space, carrying cytoplasmic contents. This process is distinct from exosome secretion and is dependent on cell migration.
Structure and Composition of migrasome
In simple terms: Migrasomes are bubble-like structures with a unique protein coat, mainly made of tetraspanins, that help them form and carry cargo.
Migrasomes are vesicular organelles with a diameter typically ranging from 0.5 to 3 micrometers, and they contain numerous smaller vesicles inside. Their membrane is enriched in tetraspanins, especially CD9, CD81, and CD63, which form macrodomains essential for their structure. Proteomic analyses have identified cytoplasmic proteins, mitochondrial fragments, and other cargo within migrasomes. The organelle lacks a classical bilayer-bound nucleus but is bounded by a lipid bilayer and is associated with the retraction fiber cytoskeleton. The tetraspanin macrodomains are thought to provide mechanical stability and curvature to the forming migrasome.
Molecular Mechanism of migrasome Formation
In simple terms: Specific lipids and proteins on the cell membrane work together to build the migrasome, like a construction crew assembling a bubble.
The molecular mechanism of migrasome formation centers on the assembly of tetraspanin macrodomains, which are micron-scale platforms enriched in CD9 and CD81. These macrodomains are stabilized by interactions with the cytoskeleton and require cholesterol and other lipids. The PI(4,5)P2-Rab35 axis is a key regulatory pathway: PI(4,5)P2 recruits Rab35 to the retraction fiber membrane, and Rab35 activity is required for migrasome formation. Additionally, integrins and other adhesion molecules on retraction fibers may anchor the macrodomains and facilitate cargo recruitment. The process is energy-dependent and involves membrane remodeling, but the exact molecular triggers for vesicle budding remain under investigation.
Regulation of migrasome Biogenesis
In simple terms: The cell controls when and where migrasomes form using signals, such as lipids and small GTPases, that act like switches.
Migrasome biogenesis is regulated by the phosphatidylinositol (4,5)-bisphosphate-Rab35 axis, which links lipid signaling to membrane trafficking. Rab35 is a small GTPase that cycles between active GTP-bound and inactive GDP-bound states; its activation promotes migrasome formation. Other regulators include tetraspanin expression levels, as knockdown of CD9 or CD81 reduces migrasome numbers. The process is also influenced by cell migration speed and substrate adhesion, since retraction fibers are required. Recent studies suggest that additional Rab proteins and membrane contact sites may fine-tune migrasome formation, but these are not yet fully defined.
Cargo Selection and Release
In simple terms: Migrasomes pack up specific cellular materials, like worn-out mitochondria, and release them outside the cell.
Migrasomes selectively package cytoplasmic contents, including damaged mitochondria, for release. This process, termed mitocytosis, involves the transport of mitochondria into migrasomes and their subsequent release for degradation by surrounding cells. Cargo selection may depend on interactions with tetraspanin macrodomains and cytoskeletal motors, although the precise mechanisms are still being elucidated. The release of migrasomes occurs when retraction fibers break or retract, allowing the organelle to detach. This cargo release can influence neighboring cells and contribute to intercellular communication.
Key Genes Involved in GO:0140494 migrasome
The following genes and proteins are central to migrasome biology, based on published literature.
| Gene | Major Role | Research Relevance |
|---|---|---|
| CD9 | Tetraspanin component of migrasome macrodomains | Essential for migrasome formation; knockdown reduces migrasome numbers |
| CD81 | Tetraspanin component of migrasome macrodomains | Required for macrodomain assembly and migrasome biogenesis |
| CD63 | Tetraspanin enriched in migrasome membranes | Marker for migrasome detection and isolation |
| Rab35 | Small GTPase regulating migrasome formation | Key regulator in the PI(4,5)P2-Rab35 axis |
| PIP5K | Kinase producing PI(4,5)P2 | Provides lipid substrate for Rab35 recruitment |
| Integrin beta 1 | Adhesion receptor on retraction fibers | Anchors retraction fibers and may influence migrasome positioning |
| Actin | Cytoskeletal component of retraction fibers | Provides structural support for migrasome formation |
| Myosin | Motor protein involved in retraction fiber dynamics | May regulate tension and migrasome release |
| Mitochondrial proteins | Cargo in mitocytosis | Damaged mitochondria are packaged into migrasomes |
| LC3 | Autophagy-related protein | May be involved in cargo selection for mitocytosis |
| Rab7 | Late endosomal GTPase | Potential role in migrasome cargo trafficking |
| Rab11 | Recycling endosome GTPase | May contribute to membrane supply for migrasome growth |
| ESCRT components | Membrane remodeling machinery | Potential role in migrasome scission, though not fully established |
| Cholesterol | Membrane lipid | Required for tetraspanin macrodomain stability |
| Sphingomyelin | Membrane lipid | Enriched in migrasome membranes |
| Tetraspanin 4 | Tetraspanin family member | May compensate for CD9/CD81 in some contexts |
| Tetraspanin 7 | Tetraspanin family member | Potential regulator of migrasome formation |
How Is migrasome Regulated?
Migrasome formation is regulated by the phosphatidylinositol (4,5)-bisphosphate-Rab35 axis, which couples lipid signaling to membrane trafficking. Rab35 activation, likely through guanine nucleotide exchange factors, promotes migrasome biogenesis, while its inactivation reduces migrasome numbers. Tetraspanin expression levels also regulate migrasome formation, as CD9 and CD81 are essential for macrodomain assembly. Cell migration speed and substrate adhesion influence the availability of retraction fibers, thereby affecting migrasome production. Additionally, cargo availability, such as damaged mitochondria, can modulate mitocytosis. Other regulatory layers, including post-translational modifications of tetraspanins and interactions with the cytoskeleton, are areas of active investigation.
migrasome and Human Disease
| Gene | Disease / Biology | Potential Experimental Model |
|---|---|---|
| CD9 | Cancer metastasis | CD9 knockout cancer cell lines for migration and invasion assays |
| CD81 | Immune regulation | CD81 knockout immune cells for migrasome and cytokine profiling |
| Rab35 | Cancer and inflammation | Rab35 point-mutation (GTP/GDP-locked) knock-in cell lines |
| Mitochondrial proteins | Neurodegeneration | Mitocytosis reporter cells with tagged mitochondrial proteins |
| Tetraspanin 4 | Cancer | Overexpression and knockout models to assess migrasome formation |
Migrasomes in Cancer
Migrasomes have been implicated in cancer progression through their role in cell-cell communication within the tumor microenvironment. They can transfer oncogenic proteins and other cargo between cancer cells and stromal cells, potentially promoting proliferation, invasion, and metastasis. The migration-dependent nature of migrasome formation suggests they may be particularly relevant in metastatic cells that actively migrate. However, direct causal evidence linking migrasome-specific genes to cancer outcomes is still emerging, and further studies are needed.
Migrasomes in Inflammation and Immunity
Migrasomes may participate in immune regulation by transferring antigens or inflammatory mediators between immune cells. Their cargo can include mitochondrial DNA, which can trigger inflammatory responses when released. In the context of infection, migrasomes could serve as vehicles for pathogen spread or immune surveillance. The exact roles of migrasomes in inflammation are not yet fully defined, but they represent a novel area of investigation.
Migrasomes in Neurodegeneration
The role of migrasomes in neurodegeneration is largely speculative, but their involvement in mitochondrial quality control via mitocytosis suggests a potential link to neurodegenerative diseases characterized by mitochondrial dysfunction. If migrasome-mediated clearance of damaged mitochondria is impaired, it could contribute to neuronal stress. However, direct evidence in neurodegeneration models is currently limited, and this remains a hypothesis-generating area.
From migrasome-Related Genes to Experimental Models
| Research Question | Suitable Model |
|---|---|
| Does CD9 loss reduce migrasome formation? | CD9 knockout cell line (e.g., HeLa) with live-cell imaging |
| Does Rab35 activation increase migrasome numbers? | Rab35 constitutively active knock-in or overexpression |
| Is PI(4,5)P2 required for migrasome biogenesis? | PIP5K knockout or knockdown with rescue |
| What cargo is packaged into migrasomes? | Tagged mitochondrial reporter knock-in for mitocytosis |
| Can migrasomes transfer functional proteins? | Co-culture of donor cells expressing tagged cargo with recipient cells |
| What is the role of tetraspanin macrodomains? | CD81 tagged knock-in for live imaging of macrodomain assembly |
How to Study the migrasome Process
| Method | What It Measures | Typical Application |
|---|---|---|
| Live-cell imaging | Migrasome formation dynamics | Tracking tetraspanin-positive structures on retraction fibers |
| Proteomics | Protein cargo composition | Identifying migrasome-enriched proteins |
| CRISPR knockout screen | Genes required for migrasome formation | Discovering novel regulators |
| Transmission electron microscopy | Ultrastructure | Confirming migrasome morphology |
| Flow cytometry | Migrasome-associated markers | Quantifying migrasome release |
| Western blot | Protein expression and knockdown efficiency | Validating CRISPR or RNAi perturbations |
| Immunofluorescence | Localization of migrasome proteins | Visualizing tetraspanin macrodomains |
| Nanoparticle tracking analysis | Size and concentration of vesicles | Characterizing released migrasomes |
Live-Cell Imaging of Migrasomes
Live-cell imaging using fluorescently tagged tetraspanins, such as CD9-GFP or CD81-mCherry, allows real-time visualization of migrasome formation on retraction fibers. This method can quantify migrasome number, size, and dynamics in migrating cells. Time-lapse microscopy is typically used to track individual migrasomes from nucleation to release.
Proteomic Analysis of Migrasomes
Purification of migrasomes from conditioned medium followed by mass spectrometry can identify their protein cargo. This approach has revealed enrichment of tetraspanins, mitochondrial proteins, and cytoskeletal components. Proteomics is useful for comparing migrasome cargo under different conditions or genetic perturbations.
CRISPR Screens for Migrasome Regulators
Genome-wide CRISPR knockout screens can identify genes required for migrasome formation. Cells are infected with a sgRNA library, and migrasome-positive cells are sorted or imaged to find regulators. This method is powerful for discovering novel components of the migrasome machinery.
Electron Microscopy
Transmission electron microscopy (TEM) provides ultrastructural details of migrasomes, including their internal vesicles and membrane morphology. Correlative light and electron microscopy (CLEM) can link fluorescence signals to ultrastructure. TEM is essential for confirming migrasome identity and purity.
How CRISPR Can Be Used to Study GO:0140494 migrasome
Knockout
CRISPR knockout of genes such as CD9, CD81, or Rab35 can abolish or reduce migrasome formation, providing causal evidence for their roles. Knockout cell lines are generated by introducing frameshift mutations and validated by western blot or sequencing. These models are useful for studying the loss of migrasome-mediated functions, such as mitocytosis.
Point Mutation
Point mutations can be introduced to study specific domains or residues, such as Rab35 GTP/GDP-locked mutants, to dissect their role in migrasome formation. CRISPR-based base editing or homology-directed repair can create these precise mutations. Such models help distinguish between activation and inactivation states.
Knock-in
Knock-in of fluorescent tags, such as CD9-GFP or CD81-mCherry, allows live imaging of migrasomes without overexpression artifacts. Tagged knock-in cell lines can also be used for proteomic pull-downs to identify interacting partners. This approach preserves endogenous regulation of the target gene.
Overexpression
Overexpression of tetraspanins or Rab35 can increase migrasome formation and is useful for gain-of-function studies. However, overexpression may cause artifacts, so results should be validated with endogenous knock-in models. Overexpression is often used in combination with knockout for rescue experiments.
How EDITGENE Supports migrasome Research
Researchers studying migrasome-related genes often need to determine whether a candidate gene is causally involved in migrasome formation, cargo selection, or function. EDITGENE provides a comprehensive suite of CRISPR-based services to create precisely engineered cell models for such investigations, from knockout to knock-in and library screening.
Contact EDITGENE today to design your custom CRISPR model for migrasome research.
Frequently Asked Questions About migrasome
What is a migrasome?
A migrasome is a vesicular organelle that forms on retraction fibers behind migrating cells and mediates the release of cytoplasmic contents during cell migration, as defined by GO:0140494.
What genes are involved in migrasome formation?
Key genes include tetraspanins CD9 and CD81, which form macrodomains, and Rab35, which regulates migrasome formation through the PI(4,5)P2-Rab35 axis.
How are migrasomes different from exosomes?
Migrasomes are larger (0.5-3 micrometers) and form on retraction fibers in a migration-dependent manner, whereas exosomes are smaller and originate from multivesicular bodies.
What is the function of migrasomes?
Migrasomes mediate the release of cytoplasmic contents, including damaged mitochondria during mitocytosis, and facilitate cell-cell communication.
What is mitocytosis?
Mitocytosis is a migrasome-mediated mitochondrial quality-control process in which damaged mitochondria are packaged into migrasomes and released for degradation.
How can I study migrasomes in the lab?
Common methods include live-cell imaging of fluorescently tagged tetraspanins, proteomics of purified migrasomes, and CRISPR screens for regulators.
Are migrasomes involved in disease?
Migrasomes have been implicated in cancer, inflammation, and potentially neurodegeneration, though research is ongoing.
What is the GO term for migrasome?
The Gene Ontology term is GO:0140494, classified under cellular_component, defined as a vesicular organelle that forms on retraction fibers behind migrating cells.
Can migrasomes transfer mitochondria?
Yes, migrasomes can carry damaged mitochondria and release them into the extracellular space as part of mitocytosis.
What CRISPR models are available for migrasome research?
Knockout, point mutation, knock-in, and overexpression models for genes like CD9, CD81, and Rab35 can be generated to study migrasome biology.
Conclusion
The migrasome (GO:0140494) is a unique migration-dependent organelle that has emerged as a key player in extracellular vesicle biology, mitochondrial quality control, and cell-cell communication. Its formation relies on tetraspanin macrodomains and the PI(4,5)P2-Rab35 axis, providing a molecular framework for understanding how cells build specialized organelles. As research advances, migrasomes may offer new insights into cancer, inflammation, and other diseases, and CRISPR-based models will be essential for dissecting their functions.
References
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