GO:0070086 ubiquitin-dependent endocytosis: Protein Sorting Pathway, Genes, Functions and Research Methods
Research-grade guide for scientists and biopharma professionals
Key Takeaways
• GO:0070086 ubiquitin-dependent endocytosis is the process by which plasma membrane proteins are tagged with ubiquitin and then internalized for delivery to the vacuole or lysosome.
• Ubiquitination acts as a sorting signal that is recognized by endocytic adaptors and the ESCRT machinery to route cargo into vesicles.
• This pathway controls the surface levels of receptors, transporters, and signaling complexes, thereby shaping cellular responses to nutrients, growth factors, and immune stimuli.
• Defects in ubiquitin-dependent endocytosis contribute to cancer, neurodegeneration, and immune disorders.
• Key experimental approaches include CRISPR knockout of E3 ligases or adaptors, tagged knock-in of cargo proteins, and proteomic or imaging-based trafficking assays.
• EDITGENE provides CRISPR cell model services to dissect ubiquitin-dependent endocytosis in any cell type.
Description
Ubiquitin-dependent endocytosis (GO:0070086) is a conserved cellular process in which a plasma membrane protein must be modified by ubiquitination to be internalized via endocytosis. This modification serves as a signal for the recruitment of endocytic machinery, leading to the internalization of the protein into vesicles and its subsequent delivery to the vacuole or lysosome for degradation. The term encompasses the entire route from ubiquitin attachment at the cell surface to lysosomal/vacuolar turnover, and it is distinct from ubiquitin-independent endocytic pathways. Researchers study this process because it regulates the abundance of many surface receptors and transporters, thereby controlling nutrient uptake, signal transduction, and immune recognition. The pathway is also a paradigm for understanding how ubiquitin acts as a sorting signal beyond proteasomal degradation.
ubiquitin-dependent endocytosis At A Glance
| GO ID | GO:0070086 |
|---|---|
| GO term | ubiquitin-dependent endocytosis |
| Ontology | biological_process |
| Synonym | ubiquitin-mediated endocytosis |
| Major function | Internalization and lysosomal/vacuolar degradation of ubiquitinated plasma membrane proteins |
| Definition | Endocytosis of a protein that requires the substrate to be modified by ubiquitination. |
| Related pathways | Ubiquitin-dependent sorting, ESCRT-mediated sorting, receptor downregulation |
| Cellular location | Plasma membrane, endosomes, lysosome/vacuole |
| Key machinery | E3 ubiquitin ligases, ubiquitin-binding adaptors, ESCRT complexes |
What Is GO:0070086?
According to the Gene Ontology, ubiquitin-dependent endocytosis is defined as endocytosis of a protein that requires the substrate to be modified by ubiquitination. Several plasma membrane proteins, including cell surface permeases and some receptors, are targeted for internalization by endocytosis, and are thereafter delivered to the vacuole or lysosome, where they are degraded. This process is also known as ubiquitin-mediated endocytosis.
Why Is ubiquitin-dependent endocytosis Important in Cell Biology?
Ubiquitin-dependent endocytosis is essential for maintaining cellular homeostasis by controlling the surface expression of receptors, transporters, and signaling molecules. It allows cells to rapidly adjust to environmental changes, such as nutrient availability or immune challenges, by removing or downregulating specific membrane proteins. Dysregulation of this pathway is linked to cancer, neurodegeneration, and immune disorders, making it a critical area for therapeutic intervention.
• Controls nutrient uptake by regulating surface permeases and transporters.
• Downregulates growth factor receptors to prevent uncontrolled signaling.
• Shapes immune responses by modulating receptor complexes on NK and B cells.
• Protects neurons by clearing damaged or excess membrane proteins.
• Provides a mechanism for ubiquitin to act as a sorting signal beyond proteasomal degradation.
• Involved in viral entry and pathogenesis by mediating internalization of viral receptors.
• Contributes to cancer progression when E3 ligases or adaptors are mutated.
• Offers targets for therapeutic intervention in immune and neurological diseases.
• Essential for vacuolar/lysosomal degradation of plasma membrane proteins in yeast and mammals.
• Regulates cell surface proteome dynamics in response to stress.
What Happens During ubiquitin-dependent endocytosis?
Substrate Recognition and Ubiquitination
In simple terms: First, the target protein on the cell surface gets tagged with a ubiquitin molecule.
The process begins when a plasma membrane protein is recognized by an E3 ubiquitin ligase, which attaches one or more ubiquitin molecules to lysine residues on the substrate. This ubiquitination can be triggered by specific signals, such as ligand binding or changes in nutrient status. The type and length of the ubiquitin chain can influence the subsequent sorting steps.
Recruitment of Endocytic Machinery
In simple terms: The ubiquitin tag is recognized by proteins that pull the tagged protein into the cell.
Ubiquitin-binding adaptor proteins, such as those containing UBA or UIM domains, recognize the ubiquitinated cargo and recruit components of the endocytic machinery, including clathrin and associated factors. This leads to the formation of a coated pit and subsequent internalization of the cargo into an endocytic vesicle.
Sorting into the Endosomal System
In simple terms: Once inside, the tagged protein is sorted into vesicles that will carry it to the degradation station.
After internalization, the cargo is delivered to early endosomes, where it is sorted into intraluminal vesicles (ILVs) by the ESCRT (Endosomal Sorting Complex Required for Transport) machinery. The ESCRT complexes recognize ubiquitinated cargo and facilitate its packaging into ILVs, which eventually form multivesicular bodies (MVBs).
Delivery to Lysosome or Vacuole
In simple terms: Finally, the tagged protein is transported to the lysosome or vacuole and broken down.
MVBs fuse with the lysosome (in mammalian cells) or vacuole (in yeast), delivering the ubiquitinated cargo to the hydrolytic lumen where it is degraded. This step completes the downregulation of the surface protein and allows its components to be recycled.
Key Genes Involved in GO:0070086 ubiquitin-dependent endocytosis
The following genes and proteins are key components of the ubiquitin-dependent endocytosis pathway, based on published literature.
| Gene | Major Role | Research Relevance |
|---|---|---|
| UBE3A | E3 ubiquitin ligase that ubiquitinates target proteins | Implicated in Angelman syndrome and synaptic function |
| NEDD4 | E3 ubiquitin ligase that ubiquitinates membrane receptors | Regulates receptor downregulation in cancer |
| RNF41 | E3 ubiquitin ligase for receptor sorting | Controls cytokine receptor trafficking |
| STAM1 | Ubiquitin-binding adaptor in ESCRT-0 | Essential for endosomal sorting of ubiquitinated cargo |
| HRS | Ubiquitin-binding adaptor in ESCRT-0 | Required for MVB formation and receptor degradation |
| TSG101 | Component of ESCRT-I | Mediates sorting of ubiquitinated cargo into ILVs |
| VPS4 | AAA-ATPase that disassembles ESCRT complexes | Regulates ESCRT cycling and cargo sorting |
| EPS15 | Ubiquitin-binding endocytic adaptor | Links ubiquitinated cargo to clathrin-mediated endocytosis |
| EPN1 | Epsin, ubiquitin-binding endocytic adaptor | Facilitates membrane curvature and cargo recruitment |
| CLTC | Clathrin heavy chain | Forms coat around endocytic vesicles |
| DNM2 | Dynamin 2, GTPase for vesicle scission | Required for endocytic vesicle formation |
| RAB5A | Early endosome marker and regulator | Controls endosomal fusion and sorting |
| RAB7A | Late endosome/lysosome regulator | Mediates MVB fusion with lysosome |
| VPS28 | Component of ESCRT-I | Involved in cargo sorting and MVB biogenesis |
| VPS36 | Component of ESCRT-II | Binds ubiquitinated cargo and facilitates ILV formation |
| CHMP4B | Component of ESCRT-III | Mediates membrane scission during ILV formation |
| UBQLN2 | Ubiquitin-like protein involved in protein degradation | Linked to neurodegeneration |
How Is ubiquitin-dependent endocytosis Regulated?
Ubiquitin-dependent endocytosis is regulated at multiple levels. The activity of E3 ubiquitin ligases can be controlled by phosphorylation, autoinhibition, or interaction with regulatory subunits. For example, NEDD4 is regulated by calcium and phospholipids. Additionally, the availability of ubiquitin-binding adaptors and the composition of ESCRT complexes are dynamically regulated in response to cellular signals. In neurons, the process is modulated by synaptic activity and stress pathways. The mTOR pathway can influence endocytosis by controlling nutrient transporter turnover.
ubiquitin-dependent endocytosis and Human Disease
| Gene | Disease / Biology | Potential Experimental Model |
|---|---|---|
| UBE3A | Angelman syndrome, synaptic dysfunction | Knockout mouse neurons, iPSC-derived neurons |
| NEDD4 | Cancer, receptor downregulation | Cancer cell lines with NEDD4 KO |
| UBQLN2 | Amyotrophic lateral sclerosis | Patient-derived motor neurons, overexpression models |
| STAM1 | Immune deficiency, sorting defects | KO cell lines, immune cells |
| VPS4 | Cancer, ESCRT dysfunction | KO cell lines, xenograft models |
Cancer
Dysregulation of ubiquitin-dependent endocytosis can lead to uncontrolled cell surface signaling. For instance, mutations in E3 ligases such as NEDD4 or loss of ESCRT components result in accumulation of growth factor receptors, promoting tumorigenesis. Targeting this pathway is a potential therapeutic strategy.
Neurodegeneration
Neurons rely heavily on ubiquitin-dependent endocytosis to clear damaged membrane proteins. Defects in this pathway, including mutations in UBQLN2 or UBE3A, are associated with neurodegenerative diseases such as amyotrophic lateral sclerosis and Angelman syndrome.
Immune Disorders
Ubiquitin-dependent endocytosis regulates immune receptor signaling. In NK cells, ubiquitination of NKG2D-DAP10 complexes is required for activation, and defects can impair immune surveillance. Similarly, B cell receptor function depends on ubiquitin-dependent trafficking.
From ubiquitin-dependent endocytosis-Related Genes to Experimental Models
| Research Question | Suitable Model |
|---|---|
| Does loss of E3 ligase affect receptor surface levels? | CRISPR knockout of E3 ligase in HeLa or HEK293 cells |
| Does a point mutation in ubiquitin acceptor site block endocytosis? | Point mutation knock-in of lysine-to-arginine in cargo protein |
| Can tagged cargo be visualized in live cells? | Knock-in of fluorescent tag (e.g., GFP) on cargo protein |
| Does overexpression of adaptor enhance degradation? | Overexpression of ubiquitin-binding adaptor |
| Which genes are essential for ubiquitin-dependent endocytosis? | Genome-wide CRISPR library screening |
| How does ubiquitination affect protein interactions? | Proteomics with ubiquitin remnant enrichment |
How to Study the ubiquitin-dependent endocytosis Process
| Method | What It Measures | Typical Application |
|---|---|---|
| CRISPR knockout screening | Gene essentiality for endocytosis | Identify novel regulators |
| Ubiquitin remnant proteomics | Ubiquitinated proteins and sites | Map substrates and dynamics |
| Live-cell imaging | Internalization and trafficking kinetics | Visualize cargo movement |
| RNA-seq | Transcriptional changes | Identify pathway regulation |
| Flow cytometry | Surface receptor levels | Quantify downregulation |
| Immunoprecipitation | Protein interactions | Identify adaptor-cargo complexes |
| Western blot | Protein degradation | Measure lysosomal turnover |
CRISPR Knockout Screens
Genome-wide CRISPR knockout screens can identify genes required for ubiquitin-dependent endocytosis. Cells are infected with a library, selected for a phenotype (e.g., surface receptor levels), and sgRNAs are sequenced to identify enriched or depleted genes.
Proteomics and Ubiquitin Remnant Profiling
Mass spectrometry-based proteomics can quantify ubiquitinated proteins and map ubiquitination sites. Enrichment of di-glycine remnants after trypsin digestion allows identification of ubiquitinated substrates.
Live-Cell Imaging
Fluorescently tagged cargo proteins and endocytic markers can be imaged in live cells to track internalization and trafficking to lysosomes. This provides spatiotemporal information about the pathway.
RNA-seq and Transcriptomics
RNA sequencing can reveal transcriptional changes in genes involved in ubiquitin-dependent endocytosis under different conditions, helping to identify regulatory networks.
How CRISPR Can Be Used to Study GO:0070086 ubiquitin-dependent endocytosis
Knockout
CRISPR knockout of E3 ligases, adaptors, or ESCRT components can abolish ubiquitin-dependent endocytosis, leading to accumulation of surface cargo. This is useful to test necessity of a gene in the pathway.
Point Mutation
Introducing point mutations in the ubiquitin acceptor lysine of a cargo protein can prevent its ubiquitination and internalization, providing a clean way to study the requirement for ubiquitination.
Knock-in
Knock-in of a fluorescent or affinity tag on a cargo protein allows tracking of its trafficking and interaction partners in live cells or lysates.
Overexpression
Overexpression of a wild-type or mutant E3 ligase or adaptor can enhance or disrupt endocytosis, helping to dissect gain-of-function effects.
How EDITGENE Supports ubiquitin-dependent endocytosis Research
Researchers studying ubiquitin-dependent endocytosis-related genes often need to determine whether a candidate gene is causally involved in the pathway. EDITGENE provides comprehensive CRISPR cell model services to accelerate this research.
Contact EDITGENE today to design your custom CRISPR model for ubiquitin-dependent endocytosis research.
Frequently Asked Questions About ubiquitin-dependent endocytosis
What is ubiquitin-dependent endocytosis?
Ubiquitin-dependent endocytosis is a cellular process where proteins on the cell surface are tagged with ubiquitin and then internalized for degradation in the lysosome or vacuole.
What genes are involved in ubiquitin-dependent endocytosis?
Key genes include E3 ubiquitin ligases (e.g., NEDD4, UBE3A), ubiquitin-binding adaptors (e.g., EPS15, EPN1), and ESCRT components (e.g., TSG101, VPS4).
What is the GO ID for ubiquitin-dependent endocytosis?
The Gene Ontology ID is GO:0070086.
How does ubiquitination target proteins for endocytosis?
Ubiquitination serves as a signal recognized by adaptor proteins that recruit the endocytic machinery, leading to internalization.
What diseases are linked to defects in ubiquitin-dependent endocytosis?
Defects are associated with cancer, neurodegeneration (e.g., ALS), and immune disorders.
What is the difference between ubiquitin-dependent and independent endocytosis?
Ubiquitin-dependent endocytosis requires the substrate to be ubiquitinated, whereas ubiquitin-independent pathways do not.
How can I study ubiquitin-dependent endocytosis in the lab?
Common methods include CRISPR knockout of pathway genes, live-cell imaging of tagged cargo, and proteomics to identify ubiquitinated proteins.
What is the role of ESCRT in ubiquitin-dependent endocytosis?
ESCRT complexes recognize ubiquitinated cargo on endosomes and sort them into intraluminal vesicles for degradation.
Can CRISPR be used to study ubiquitin-dependent endocytosis?
Yes, CRISPR knockout, knock-in, and point mutation models are powerful tools to dissect the pathway.
What services does EDITGENE offer for ubiquitin-dependent endocytosis research?
EDITGENE provides knockout, point mutation, knock-in, overexpression cell models, CRISPR library screening, and bioinformatics services.
Conclusion
Ubiquitin-dependent endocytosis (GO:0070086) is a fundamental cellular process that controls the surface proteome by targeting ubiquitinated proteins for lysosomal degradation. Its dysregulation underlies various diseases, making it a vibrant area of research. Leveraging CRISPR-based models and advanced screening technologies, researchers can uncover new mechanistic insights and therapeutic targets.
References
- 1. Piper RC et al.. 2014. Ubiquitin-dependent sorting in endocytosis.. Cold Spring Harb Perspect Biol 6(1) PMID: 24384571
- 2. Höller D et al.. 2004. Receptor endocytosis via ubiquitin-dependent and -independent pathways.. Biochem Pharmacol 67(6):1013-7 PMID: 15006537
- 3. Schwarz LA et al.. 2012. Ubiquitin-dependent endocytosis, trafficking and turnover of neuronal membrane proteins.. Mol Cell Neurosci 49(3):387-93 PMID: 21884797
- 4. Riezman H et al.. 1996. Actin-, myosin- and ubiquitin-dependent endocytosis.. Experientia 52(12):1033-41 PMID: 8988243
- 5. Hochstrasser M. 1996. Ubiquitin-dependent protein degradation.. Annu Rev Genet 30:405-39 PMID: 8982460
- 6. Quatrini L et al.. 2015. Ubiquitin-dependent endocytosis of NKG2D-DAP10 receptor complexes activates signaling and functions in human NK cells.. Sci Signal 8(400):ra108 PMID: 26508790
- 7. Drake JR. 2018. The immunobiology of ubiquitin-dependent B cell receptor functions.. Mol Immunol 101:146-154 PMID: 29940407
- 8. Migliano SM et al.. 2018. ESCRT and Membrane Protein Ubiquitination.. Prog Mol Subcell Biol 57:107-135 PMID: 30097773
