GO:1905366 negative regulation of intralumenal vesicle formation: Endosomal Sorting Pathway, Genes, Functions and Research Methods
Research-grade guide for scientists and biopharma professionals
Key Takeaways
• GO:1905366 describes any process that stops, prevents, or reduces the frequency, rate, or extent of intralumenal vesicle (ILV) formation, the inward budding of the endosomal limiting membrane that generates multivesicular bodies (MVBs).
• The ESCRT machinery (ESCRT-0, -I, -II, -III, and Vps4) is the central protein system that drives ILV formation; negative regulation often occurs through accessory proteins that modulate ESCRT assembly or disassembly.
• Alix and Tsg101 are key positive regulators of ILV budding in vitro, and their inhibition reduces ILV formation, providing a direct experimental handle on negative regulation.
• UNC93B1 recruits syntenin-1 to dampen TLR7 signalling by altering endosomal sorting, illustrating how negative regulation of ILV formation intersects with immune regulation and autoimmunity.
• Dysregulation of ILV formation and MVB sorting is linked to cancer, neurodegeneration, and immune disorders, making GO:1905366 a relevant term for disease-focused research.
• CRISPR knockout, point-mutation, knock-in, and overexpression models enable precise dissection of negative regulators of ILV formation in a variety of cell types.
Description
Intralumenal vesicle (ILV) formation is the process by which the endosomal limiting membrane buds inward to create vesicles within the lumen of late endosomes, forming multivesicular bodies (MVBs). This process is essential for sorting cargo such as activated receptors, lipids, and signalling molecules into the endosomal lumen, ultimately influencing degradation, exosome secretion, and cellular signalling. The Gene Ontology term GO:1905366, negative regulation of intralumenal vesicle formation, captures any process that stops, prevents, or reduces the frequency, rate, or extent of this inward budding event. Understanding this negative regulation is critical because excessive or misregulated ILV formation can alter receptor downregulation, exosome cargo, and immune signalling, with consequences for diseases ranging from autoimmunity to neurodegeneration. The molecular machinery that executes ILV formation is the endosomal sorting complex required for transport (ESCRT) pathway, comprising ESCRT-0, -I, -II, -III, and the AAA-ATPase Vps4. Negative regulation of ILV formation can occur at multiple steps: inhibition of ESCRT assembly, enhanced disassembly by Vps4, sequestration of ESCRT components, or recruitment of accessory proteins that dampen budding. For example, Alix and Tsg101 are required for efficient ILV budding in vitro, and their depletion reduces ILV formation, effectively acting as positive regulators whose loss constitutes negative regulation. Conversely, Bro1 (the yeast orthologue of Alix) binds Vps20 and promotes ESCRT-III regulation by Doa4, revealing layers of control that can either enhance or suppress ILV formation depending on context. Research on GO:1905366 has gained traction because ILV formation sits at the crossroads of endosomal sorting, exosome biogenesis, and immune surveillance. UNC93B1, a chaperone for Toll-like receptors, recruits syntenin-1 to dampen TLR7 signalling, a process that involves altered endosomal sorting and likely impacts ILV dynamics. In neurons, cholesterol accumulation in endosomes increases exosome secretion, suggesting that lipid environment modulates ILV formation and its negative regulation. These findings underscore the importance of identifying and characterizing negative regulators of ILV formation to understand both basic cell biology and disease mechanisms.
negative regulation of intralumenal vesicle formation At A Glance
| GO ID | GO:1905366 |
|---|---|
| GO term | negative regulation of intralumenal vesicle formation |
| Ontology | biological_process |
| Synonym | down regulation of endosome membrane budding; inhibition of intralumenal vesicle formation; negative regulation of endosome membrane budding |
| Major function | Stops, prevents, or reduces the inward budding of the endosomal membrane that generates intralumenal vesicles within multivesicular bodies. |
| Key machinery | ESCRT-0, ESCRT-I, ESCRT-II, ESCRT-III, Vps4, Alix, Tsg101, Bro1, Doa4. |
| Cellular context | Endosomal sorting, multivesicular body biogenesis, exosome secretion, receptor downregulation. |
| Disease relevance | Autoimmunity, cancer, neurodegeneration, and disorders of endosomal trafficking. |
| Research methods | In vitro budding assays, CRISPR knockout, live-cell imaging, proteomics, and exosome analysis. |
What Is GO:1905366?
GO:1905366, negative regulation of intralumenal vesicle formation, is defined as any biological process that stops, prevents, or reduces the frequency, rate, or extent of intralumenal vesicle formation. Intralumenal vesicle formation itself is the inward budding of the endosomal membrane into the endosomal lumen, producing intralumenal vesicles within multivesicular bodies (MVBs). Negative regulation therefore encompasses molecular events that inhibit this budding step, such as blocking ESCRT complex assembly, promoting ESCRT disassembly, or recruiting inhibitory proteins that interfere with the budding machinery. This regulation can occur at early endosomes, late endosomes, or during MVB maturation, and it directly affects cargo sorting, receptor downregulation, and exosome release.
Why Is negative regulation of intralumenal vesicle formation Important in Cell Biology?
Negative regulation of intralumenal vesicle formation is important because it controls the flux of cargo into the endosomal lumen, thereby influencing receptor degradation, exosome cargo selection, and immune signalling. When this regulation fails, cells may overproduce or underproduce ILVs, leading to altered exosome secretion, defective receptor downregulation, and aberrant immune activation. For researchers, GO:1905366 provides a framework to identify and characterize proteins that restrain ILV budding, offering potential therapeutic targets in cancer, autoimmunity, and neurodegeneration.
• Controls endosomal sorting and receptor downregulation, affecting signalling output from growth factor and immune receptors.
• Regulates exosome biogenesis and cargo, with implications for intercellular communication in cancer and neurodegeneration.
• Modulates innate immune signalling, as exemplified by UNC93B1-syntenin-1-mediated dampening of TLR7.
• Influences neuronal homeostasis; cholesterol buildup in aging neurons increases exosome secretion via endosomal pathways.
• Provides a mechanistic entry point for understanding ESCRT-dependent processes in development and disease.
• Offers targets for therapeutic intervention in autoimmunity, where excessive TLR7 signalling contributes to disease.
• Helps interpret how ubiquitin ligases such as Rsp5 regulate MVB sorting determinants.
• Connects to EGFR trafficking and early endosome transit, relevant to cancer drug resistance.
• Enables dissection of ESCRT-III regulation by Bro1 and Doa4 in yeast models.
• Supports comparative studies of Chmp2b regulation in neuronal development and disease.
What Happens During negative regulation of intralumenal vesicle formation?
Inhibition of ESCRT assembly at the endosomal membrane
In simple terms: The cell blocks the first steps of the machinery that makes inward buds.
Intralumenal vesicle formation begins with recruitment of ESCRT-0, which binds ubiquitinated cargo and initiates assembly of ESCRT-I and ESCRT-II at the endosomal membrane. Negative regulation can occur when proteins or conditions prevent ESCRT-0 from engaging cargo or when ESCRT-I/II recruitment is impaired. For example, depletion of Tsg101, an ESCRT-I component, reduces ILV budding in vitro, indicating that loss of positive regulators effectively acts as negative regulation. Similarly, ESCRT-0 marks a transit route for EGFR between the cell surface and early endosomes, and interference with this route can suppress downstream ILV formation.
Promotion of ESCRT disassembly by Vps4
In simple terms: A molecular motor recycles the budding machinery, shutting down the process.
The AAA-ATPase Vps4 disassembles ESCRT-III filaments, a step required for recycling ESCRT components and completing ILV formation. The Vps4 C-terminal helix is critical for assembly and ATPase activity, and mutations that impair this domain reduce ESCRT-III disassembly, which can paradoxically inhibit ILV formation by trapping components. Thus, negative regulation of ILV formation can be achieved by enhancing Vps4 activity or by altering its regulation, leading to premature disassembly of the budding machinery.
Accessory proteins that dampen budding
In simple terms: Helper proteins can put the brakes on the budding process.
Accessory proteins such as Alix and Bro1 modulate ESCRT function. Alix and Tsg101 are required for in vitro budding of ILVs into late endosomes, and their inhibition reduces budding. In yeast, Bro1 binds the Vps20 subunit of ESCRT-III and promotes ESCRT-III regulation by the ubiquitin hydrolase Doa4, revealing a regulatory node that can either enhance or suppress ILV formation depending on context. UNC93B1 recruits syntenin-1 to dampen TLR7 signalling, a process that involves altered endosomal sorting and likely affects ILV dynamics, illustrating how immune-specific adaptors can negatively regulate ILV formation.
Cargo-specific regulation and ubiquitination
In simple terms: The tags on cargo proteins determine whether budding is slowed or sped up.
Ubiquitination of cargo proteins is a key signal for MVB sorting, and the ubiquitin ligase Rsp5 regulates multiple sorting determinants within Sna3. Negative regulation of ILV formation can occur when ubiquitination is reversed or when cargo is deubiquitinated, reducing the efficiency of ESCRT recruitment. For example, Doa4, a deubiquitinating enzyme, is regulated by Bro1 and can influence ESCRT-III dynamics, thereby modulating ILV formation. This cargo-specific control ensures that only appropriate cargo is sorted and that budding is tuned to cellular needs.
Lipid and environmental modulation
In simple terms: The fat composition of the endosome membrane can slow down or speed up budding.
Endosomal cholesterol accumulation in aging neurons increases exosome secretion, suggesting that lipid environment modulates ILV formation and its negative regulation. NPC1-mediated cholesterol buildup alters endosomal membrane properties, potentially affecting the efficiency of inward budding and the recruitment of ESCRT components. This highlights that negative regulation of ILV formation is not solely protein-driven but also influenced by membrane lipid composition and cellular metabolic state.
Key Genes Involved in GO:1905366 negative regulation of intralumenal vesicle formation
The following genes and proteins are central to the machinery, regulation, and cargo sorting of intralumenal vesicle formation, and their manipulation is key to studying GO:1905366.
| Gene | Major Role | Research Relevance |
|---|---|---|
| Tsg101 | ESCRT-I component; required for ILV budding | Depletion reduces ILV formation, serving as a model for negative regulation. |
| Alix | Accessory protein; promotes ILV budding and ESCRT-III regulation | Inhibition blocks in vitro ILV budding, linking to negative regulation. |
| Vps4 | AAA-ATPase; disassembles ESCRT-III | Mutations alter ESCRT recycling and ILV formation. |
| Bro1 | Yeast orthologue of Alix; binds Vps20 and regulates Doa4 | Model for ESCRT-III regulation and negative control. |
| Doa4 | Deubiquitinating enzyme; regulated by Bro1 | Modulates cargo sorting and ESCRT-III dynamics. |
| UNC93B1 | TLR chaperone; recruits syntenin-1 | Dampens TLR7 signalling via endosomal sorting. |
| Syntenin-1 | Adaptor protein; recruited by UNC93B1 | Involved in negative regulation of TLR7 signalling. |
| Chmp2b | ESCRT-III subunit; regulated by Lbx1 | Implicated in synaptogenesis and neurodegeneration. |
| Lbx1 | Transcription factor; regulates Chmp2b | Controls Chmp2b expression during neuronal development. |
| Rsp5 | Ubiquitin ligase; regulates Sna3 sorting | Controls MVB sorting determinants. |
| Sna3 | Cargo protein with multiple MVB sorting determinants | Model for ubiquitin-dependent sorting. |
| EGFR | Receptor tyrosine kinase; sorted via ESCRT-0 | Trafficking links to cancer and ILV formation. |
| NPC1 | Cholesterol transporter; affects endosomal lipid environment | Cholesterol buildup increases exosome secretion. |
| Vps20 | ESCRT-III subunit; binds Bro1 | Target of Bro1 regulation. |
| Vps36 | ESCRT-II subunit | Part of the ESCRT machinery for ILV formation. |
| Vps25 | ESCRT-II subunit | Component of ESCRT-II. |
| Vps22 | ESCRT-II subunit | Component of ESCRT-II. |
How Is negative regulation of intralumenal vesicle formation Regulated?
Negative regulation of intralumenal vesicle formation is controlled at multiple levels. ESCRT assembly and disassembly are regulated by ATP-dependent Vps4 activity, which recycles ESCRT-III subunits and can terminate budding. Ubiquitination and deubiquitination of cargo and machinery components, mediated by enzymes such as Rsp5 and Doa4, provide reversible control points. Accessory proteins like Alix, Bro1, and syntenin-1 modulate ESCRT function in a context-dependent manner. Additionally, lipid environment and cholesterol levels influence membrane budding efficiency, as seen in NPC1-mediated cholesterol accumulation in aging neurons. Transcriptional regulation of ESCRT components, such as Lbx1-mediated control of Chmp2b, adds another layer of control during development.
negative regulation of intralumenal vesicle formation and Human Disease
| Gene | Disease / Biology | Potential Experimental Model |
|---|---|---|
| UNC93B1 | Autoimmunity, TLR7-driven lupus | Knockout or point-mutation in immune cells |
| CHMP2B | Frontotemporal dementia, neurodegeneration | Knock-in of disease mutations in neurons |
| NPC1 | Niemann-Pick disease type C, neuronal aging | Knockout or overexpression in neuronal cultures |
| EGFR | Cancer, receptor trafficking | Knockout or tagged knock-in in cancer cell lines |
| Tsg101 | Cancer, viral budding | Knockout or knockdown in HeLa or HEK293 cells |
Autoimmunity and TLR7 signalling
UNC93B1 recruits syntenin-1 to dampen TLR7 signalling and prevent autoimmunity, a process that involves negative regulation of endosomal sorting and likely ILV formation. Dysregulation of this pathway can lead to excessive TLR7 activation, contributing to autoimmune diseases such as systemic lupus erythematosus. Understanding how negative regulation of ILV formation impacts TLR7 trafficking may reveal therapeutic targets for autoimmunity.
Neurodegeneration and neuronal aging
In neurons aging in vitro, NPC1-mediated endosomal cholesterol buildup increases exosome secretion, suggesting that altered ILV formation and its negative regulation contribute to neuronal aging and neurodegeneration. Chmp2b, an ESCRT-III subunit, is regulated by Lbx1 during synaptogenesis, and mutations in CHMP2B are linked to frontotemporal dementia. These findings connect GO:1905366 to neurodegenerative disease mechanisms.
Cancer and receptor trafficking
ESCRT-0 marks a transit route for EGFR between the cell surface and early endosomes, and negative regulation of ILV formation can influence EGFR downregulation and signalling duration. Aberrant ILV formation may alter exosome cargo, impacting tumor microenvironment communication. Targeting negative regulators of ILV formation could modulate receptor tyrosine kinase signalling in cancer.
From negative regulation of intralumenal vesicle formation-Related Genes to Experimental Models
| Research Question | Suitable Model |
|---|---|
| Does loss of a candidate gene increase ILV formation? | CRISPR knockout in HeLa or HEK293 cells followed by in vitro budding assay |
| Does a point mutation in Vps4 alter ESCRT disassembly? | Point-mutation knock-in of Vps4 variants |
| Does tagging a protein affect its localization during ILV formation? | Tagged knock-in of ESCRT components with fluorescent proteins |
| Does overexpression of syntenin-1 dampen TLR7 signalling? | Overexpression in immune cell lines |
| Does cholesterol accumulation alter exosome secretion? | NPC1 knockout or overexpression in neurons |
| Does Chmp2b regulation by Lbx1 affect synaptogenesis? | Knockout or knockdown in neuronal cultures |
How to Study the negative regulation of intralumenal vesicle formation Process
| Method | What It Measures | Typical Application |
|---|---|---|
| In vitro budding assay | ILV formation efficiency | Testing Alix/Tsg101 inhibition |
| Live-cell imaging | ESCRT recruitment dynamics | Tracking Vps4 or Bro1 at endosomes |
| Proteomics | Protein interactions and cargo | Identifying ESCRT regulators |
| CRISPR knockout screen | Genes affecting ILV formation | Unbiased discovery of negative regulators |
| Exosome analysis | Exosome secretion and cargo | Assessing ILV formation output |
| Ubiquitination assays | Cargo ubiquitination status | Studying Rsp5 and Doa4 |
| Electron microscopy | MVB and ILV morphology | Visualizing ILV formation |
| Flow cytometry | Receptor downregulation | Measuring EGFR trafficking |
In vitro ILV budding assays
In vitro budding assays using purified late endosomes or synthetic liposomes reconstitute ILV formation and allow direct measurement of negative regulation. Falguières et al. demonstrated that Alix and Tsg101 are required for in vitro budding of ILVs into late endosomes, and their inhibition reduces budding. This assay is ideal for testing candidate negative regulators by adding inhibitory antibodies or depleting components.
Live-cell imaging of ESCRT dynamics
Fluorescent tagging of ESCRT components such as Vps4, Bro1, or Chmp2b enables live-cell imaging of their recruitment to endosomes. This approach can reveal how negative regulators alter the timing or frequency of ILV formation. Tagged knock-in models are particularly useful for tracking endogenous proteins.
Proteomics and interactomics
Affinity purification coupled to mass spectrometry can identify proteins that interact with ESCRT components or cargo, uncovering potential negative regulators. For example, Bro1 binding to Vps20 and regulation of Doa4 was elucidated through biochemical and genetic approaches. Proteomic analysis of exosomes can also reveal changes in ILV cargo when negative regulators are manipulated.
Genetic screens and CRISPR libraries
CRISPR knockout libraries enable unbiased screens for genes that negatively regulate ILV formation. By coupling ILV formation readouts (e.g., exosome secretion or receptor degradation) with pooled screens, researchers can identify novel regulators. Such screens are powerful for discovering genes like Rsp5 or Doa4 that modulate MVB sorting.
How CRISPR Can Be Used to Study GO:1905366 negative regulation of intralumenal vesicle formation
Knockout
CRISPR knockout of candidate negative regulators can be used to test whether loss of function increases ILV formation. For example, knocking out Tsg101 reduces ILV budding, confirming its positive role, while knocking out a negative regulator would be expected to enhance budding. Knockout models are essential for establishing causality in GO:1905366 research.
Point Mutation
Point mutations in ESCRT components, such as the Vps4 C-terminal helix, can disrupt ATPase activity and ESCRT disassembly, thereby altering ILV formation. CRISPR point-mutation knock-in allows precise modeling of disease-associated variants, such as those in CHMP2B linked to frontotemporal dementia.
Knock-in
Tagged knock-in of ESCRT proteins with fluorescent or affinity tags enables visualization and purification of endogenous complexes. This is particularly useful for studying dynamic processes like ILV formation and for identifying interacting partners of negative regulators.
Overexpression
Overexpression of candidate negative regulators, such as syntenin-1 or Bro1, can suppress ILV formation and downstream processes like TLR7 signalling or exosome secretion. Overexpression models complement knockout studies by providing gain-of-function evidence.
How EDITGENE Supports negative regulation of intralumenal vesicle formation Research
Researchers studying negative regulation of intralumenal vesicle formation-related genes often need to determine whether a candidate gene is causally involved in ILV budding, how mutations affect ESCRT dynamics, and whether modulating its expression alters exosome cargo or immune signalling. EDITGENE provides the CRISPR tools and services to answer these questions with precision.
Contact EDITGENE today to design your custom CRISPR model for negative regulation of intralumenal vesicle formation research.
Frequently Asked Questions About negative regulation of intralumenal vesicle formation
What is GO:1905366?
GO:1905366 is the Gene Ontology term for negative regulation of intralumenal vesicle formation, describing any process that stops, prevents, or reduces the inward budding of the endosomal membrane to form intralumenal vesicles.
What genes are involved in negative regulation of intralumenal vesicle formation?
Key genes include Tsg101, Alix, Vps4, Bro1, Doa4, UNC93B1, syntenin-1, Chmp2b, and Rsp5, which modulate ESCRT assembly, disassembly, or cargo sorting.
How is intralumenal vesicle formation negatively regulated?
It can be negatively regulated by inhibiting ESCRT assembly, promoting Vps4-mediated disassembly, recruiting accessory proteins like syntenin-1, or altering cargo ubiquitination.
What is the role of ESCRT in intralumenal vesicle formation?
ESCRT complexes (0, I, II, III) and Vps4 drive the inward budding of the endosomal membrane to form intralumenal vesicles, and their regulation determines the rate of ILV formation.
Which diseases are linked to negative regulation of intralumenal vesicle formation?
Autoimmunity, neurodegeneration, and cancer have been linked to dysregulated ILV formation and ESCRT function.
How can I study negative regulation of intralumenal vesicle formation in the lab?
Common methods include in vitro budding assays, live-cell imaging of ESCRT components, CRISPR knockout screens, and exosome analysis.
What is the role of UNC93B1 in ILV formation?
UNC93B1 recruits syntenin-1 to dampen TLR7 signalling, a process involving endosomal sorting that likely impacts ILV formation and its negative regulation.
Does cholesterol affect intralumenal vesicle formation?
Yes, NPC1-mediated endosomal cholesterol buildup in aging neurons increases exosome secretion, indicating that lipid environment modulates ILV formation.
What CRISPR models are available for studying ILV formation?
Knockout, point-mutation, knock-in, tagged knock-in, and overexpression models can be generated for genes such as Tsg101, Vps4, and CHMP2B.
Why is negative regulation of intralumenal vesicle formation important?
It controls receptor downregulation, exosome cargo, and immune signalling, and its dysregulation contributes to autoimmunity, cancer, and neurodegeneration.
Conclusion
GO:1905366, negative regulation of intralumenal vesicle formation, represents a critical control point in endosomal biology that influences receptor trafficking, exosome secretion, and immune signalling. The ESCRT machinery and its accessory proteins, including Tsg101, Alix, Vps4, Bro1, and UNC93B1, are central to this regulation, and their dysfunction is linked to autoimmunity, neurodegeneration, and cancer. By leveraging CRISPR knockout, point-mutation, knock-in, and overexpression models, researchers can dissect the molecular mechanisms of negative regulation and identify new therapeutic targets. EDITGENE offers comprehensive services to support these studies, from custom cell line generation to CRISPR library screening and bioinformatics analysis.
References
- 1. Falguières T et al.. 2008. In vitro budding of intralumenal vesicles into late endosomes is regulated by Alix and Tsg101.. Mol Biol Cell 19(11):4942-55 PMID: 18768755
- 2. Majer O et al.. 2019. UNC93B1 recruits syntenin-1 to dampen TLR7 signalling and prevent autoimmunity.. Nature 575(7782):366-370 PMID: 31546246
- 3. Buysse D et al.. 2022. Bro1 binds the Vps20 subunit of ESCRT-III and promotes ESCRT-III regulation by Doa4.. Traffic 23(2):109-119 PMID: 34908216
- 4. Xu J et al.. 2012. Population-specific regulation of Chmp2b by Lbx1 during onset of synaptogenesis in lateral association interneurons.. PLoS One 7(12):e48573 PMID: 23284619
- 5. Guix FX et al.. 2021. Increased exosome secretion in neurons aging in vitro by NPC1-mediated endosomal cholesterol buildup.. Life Sci Alliance 4(8) PMID: 34183444
- 6. Oestreich AJ et al.. 2007. Characterization of multiple multivesicular body sorting determinants within Sna3: a role for the ubiquitin ligase Rsp5.. Mol Biol Cell 18(2):707-20 PMID: 17182849
- 7. Flores-Rodriguez N et al.. 2015. ESCRT-0 marks an APPL1-independent transit route for EGFR between the cell surface and the EEA1-positive early endosome.. J Cell Sci 128(4):755-67 PMID: 25588841
- 8. Vajjhala PR et al.. 2008. The Vps4 C-terminal helix is a critical determinant for assembly and ATPase activity and has elements conserved in other members of the meiotic clade of AAA ATPases.. FEBS J 275(7):1427-1449 PMID: 18266866
