GO:1990116 ribosome-associated ubiquitin-dependent protein catabolic process: Protein Quality Control Pathway, Genes, Functions and Research Methods
Research-grade guide for scientists and biopharma professionals
Key Takeaways
• GO:1990116 describes the ubiquitin-dependent degradation of nascent polypeptides encoded by aberrant or damaged mRNAs that are associated with stalled ribosomes.
• The process is initiated when a ribosome stalls on a defective mRNA, leading to ribosome collision and recruitment of quality control factors including the RQT complex.
• Cdc48/p97 (VCP) is a key ATPase that extracts ubiquitinated nascent chains from the ribosome for proteasomal degradation.
• Ribosome-associated quality control (RQC) targets premature translation termination products, such as Orf1p from ODC antizyme mRNA, for degradation.
• Dysregulation of this pathway is linked to neurodegenerative diseases and cancer, making it a target for therapeutic intervention.
• CRISPR knockout, point mutation, and knock-in models are essential tools for dissecting the molecular players in this process [1,2,3,4].
Description
The ribosome-associated ubiquitin-dependent protein catabolic process (GO:1990116) is a conserved quality control mechanism that eliminates aberrant nascent polypeptides arising from stalled translation. This pathway ensures that defective proteins do not accumulate and interfere with cellular functions, thereby maintaining proteostasis. It is triggered when a ribosome stalls on an aberrant mRNA, often due to rare codons, damaged mRNA, or premature polyadenylation, leading to ribosome collision and recruitment of quality control factors. The process involves ubiquitination of the nascent chain and its subsequent extraction from the ribosome by Cdc48/p97 for proteasomal degradation. Understanding this pathway is critical because its malfunction is associated with neurodegenerative diseases and cancer, and it provides a model for studying translation-coupled protein quality control [1,3].
ribosome-associated ubiquitin-dependent protein catabolic process At A Glance
| GO ID | GO:1990116 |
|---|---|
| GO term | ribosome-associated ubiquitin-dependent protein catabolic process |
| Ontology | biological_process |
| Synonym | RAD, ribosome-associated degradation, ribosome-associated ubiquitin-dependent protein breakdown, ribosome-associated ubiquitin-dependent protein catabolism, ribosome-associated ubiquitin-dependent protein degradation |
| Major function | Degradation of aberrant nascent polypeptides associated with stalled ribosomes |
| Key components | RQT complex, Cdc48/p97, ubiquitin ligases, proteasome |
| Associated diseases | Neurodegeneration, cancer, ribosomopathies |
| Research methods | Ribo-seq, RNA-seq, proteomics, CRISPR screens |
What Is GO:1990116?
GO:1990116, ribosome-associated ubiquitin-dependent protein catabolic process, is defined as the chemical reactions and pathways resulting in the breakdown of a protein or peptide encoded by an aberrant message and associated with a stalled ribosome. Degradation is initiated by the covalent attachment of ubiquitin groups to the ribosome-associated protein, marking it for proteasomal destruction.
Why Is ribosome-associated ubiquitin-dependent protein catabolic process Important in Cell Biology?
This process is vital for cellular proteostasis because it prevents the accumulation of potentially toxic truncated proteins that can arise from errors in translation. Defects in ribosome-associated quality control have been linked to neurodegenerative diseases such as amyotrophic lateral sclerosis and Alzheimer's disease, as well as to cancer progression [1,3]. Moreover, understanding this pathway provides insights into how cells cope with translation stress and how quality control mechanisms interface with other cellular processes like the integrated stress response.
• Maintains proteostasis by eliminating aberrant nascent polypeptides.
• Prevents aggregation of truncated proteins that can be cytotoxic.
• Involved in the cellular response to translation stress.
• Dysregulation is associated with neurodegenerative diseases.
• Plays a role in cancer biology by affecting protein homeostasis.
• Provides a model for studying translation-coupled quality control.
• Targets premature termination products for degradation.
• Requires coordinated action of ribosome splitting and ubiquitination machinery [2,4].
• Cdc48/p97 is essential for extracting ubiquitinated nascent chains.
• Offers potential therapeutic targets for diseases linked to protein misfolding.
What Happens During ribosome-associated ubiquitin-dependent protein catabolic process?
Ribosome Stalling and Collision
In simple terms: When a ribosome gets stuck on a bad mRNA, it bumps into another ribosome, triggering a rescue system.
The process begins when a ribosome stalls during translation of an aberrant mRNA, often due to rare codons, mRNA damage, or premature polyadenylation. Stalling leads to collision with a trailing ribosome, which is recognized by the RQT complex (Ribosome Quality Control Trigger complex). The RQT complex, including Slh1/Rqt2, Cue3/Rqt3, and Rqt4, dissociates the collided ribosomes in an ATP-dependent manner.
Ubiquitination of the Nascent Chain
In simple terms: The stuck protein gets tagged with ubiquitin molecules, which act like a 'destroy me' signal.
Following ribosome splitting, the nascent polypeptide remains associated with the 60S subunit and is targeted by ubiquitin ligases, such as Ltn1 in yeast and its homologs in higher eukaryotes. These ligases attach ubiquitin chains to lysine residues on the nascent chain, marking it for degradation. The ubiquitination is a key step that commits the aberrant protein to the proteasome pathway.
Extraction by Cdc48/p97
In simple terms: A molecular machine called Cdc48/p97 pulls the tagged protein out of the ribosome so it can be destroyed.
The ubiquitinated nascent chain is extracted from the ribosome by the AAA-ATPase Cdc48 in yeast (p97/VCP in humans). Cdc48/p97 recognizes ubiquitinated substrates and uses ATP hydrolysis to thread the polypeptide through its central pore, dislodging it from the ribosome. This extraction is essential for subsequent proteasomal degradation.
Proteasomal Degradation
In simple terms: The tagged protein is fed into the proteasome, a cellular garbage disposal, and broken down into small pieces.
Once extracted, the ubiquitinated nascent chain is delivered to the 26S proteasome for degradation. The proteasome recognizes the ubiquitin chains and processively degrades the polypeptide into short peptides. This final step ensures that the aberrant protein is completely eliminated, preventing its accumulation.
Coordination with Other Quality Control Pathways
In simple terms: This process works together with other cellular quality control systems to keep the cell healthy.
Ribosome-associated ubiquitin-dependent protein catabolic process is integrated with other translation quality control pathways, such as no-go decay and non-stop decay. For example, the degradation of premature termination products like Orf1p from ODC antizyme mRNA involves ribosome-associated quality control. Cross-talk with the integrated stress response ensures that cells adapt to translation stress.
Key Genes Involved in GO:1990116 ribosome-associated ubiquitin-dependent protein catabolic process
The following genes and proteins are key players in the ribosome-associated ubiquitin-dependent protein catabolic process, as supported by published literature.
| Gene | Major Role | Research Relevance |
|---|---|---|
| RQT2 (Slh1) | Component of RQT complex, ATPase involved in ribosome splitting | Essential for dissociating collided ribosomes |
| RQT3 (Cue3) | Component of RQT complex, facilitates ribosome dissociation | Required for RQC in yeast |
| RQT4 | Component of RQT complex, assists in ribosome rescue | Involved in ribosome quality control |
| LTN1 | E3 ubiquitin ligase that ubiquitinates nascent chains | Central to ubiquitination of stalled nascent polypeptides |
| CDC48 (VCP/p97) | AAA-ATPase that extracts ubiquitinated nascent chains | Critical for dislodging nascent chains from ribosomes |
| RPN1 | Proteasome subunit, recognizes ubiquitinated substrates | Facilitates degradation of extracted polypeptides |
| RPT1 | Proteasome subunit, ATPase involved in substrate unfolding | Required for proteasomal degradation |
| UBB | Ubiquitin precursor, provides ubiquitin moieties | Essential for ubiquitination of nascent chains |
| UBA1 | Ubiquitin-activating enzyme | Initiates ubiquitin conjugation cascade |
| UBE2D1 | Ubiquitin-conjugating enzyme | Transfers ubiquitin to target proteins |
| RPS3 | Ribosomal protein, part of 40S subunit | May be involved in recognizing stalled ribosomes |
| RPL28 | Ribosomal protein, part of 60S subunit | Associated with nascent chain during RQC |
| SDD1 | Endogenous RQC substrate in yeast | Model substrate for studying RQC |
| ODC1 | Ornithine decarboxylase, its mRNA produces antizyme inhibitor | Its antizyme mRNA yields Orf1p, a premature termination product degraded by RQC |
| NEMF | Nuclear export mediator factor, binds 60S subunit | Involved in RQC in higher eukaryotes |
| TCF25 | Transcription factor 25, RQC component | Plays a role in ribosome-associated quality control |
How Is ribosome-associated ubiquitin-dependent protein catabolic process Regulated?
The ribosome-associated ubiquitin-dependent protein catabolic process is regulated at multiple levels. The integrated stress response (ISR) can modulate translation initiation, affecting the load of aberrant polypeptides. Additionally, the availability of ubiquitin ligases and the activity of Cdc48/p97 are subject to regulation by post-translational modifications and cofactors. The RQT complex is recruited to collided ribosomes in a manner dependent on the collision sensor Hel2 in yeast. Furthermore, the process is intertwined with other quality control pathways, ensuring a coordinated response to translation stress.
ribosome-associated ubiquitin-dependent protein catabolic process and Human Disease
| Gene | Disease / Biology | Potential Experimental Model |
|---|---|---|
| VCP | IBMPFD, ALS | Knock-in of patient mutations in cell lines |
| LTN1 | Neurodegeneration | Knockout in neuronal cells |
| RQT2 | Ribosomopathy | Knockout in yeast or human cells |
| ODC1 | Cancer | Overexpression of antizyme mRNA in cancer cells |
| NEMF | Neurodevelopmental disorders | Knockout in mouse models |
Neurodegenerative Diseases
Defects in ribosome-associated quality control have been implicated in neurodegenerative diseases such as amyotrophic lateral sclerosis (ALS) and Alzheimer's disease. Mutations in VCP/p97, a key player in this pathway, cause inclusion body myopathy with Paget's disease of bone and frontotemporal dementia (IBMPFD) and ALS. Impaired clearance of aberrant proteins can lead to their aggregation, contributing to neuronal toxicity.
Cancer
Cancer cells often exhibit altered protein homeostasis and may rely on quality control pathways for survival under stress. Dysregulation of ribosome-associated degradation can affect the stability of oncoproteins and tumor suppressors, influencing tumor progression. Targeting this pathway could offer therapeutic opportunities, especially in cancers with high proteotoxic stress.
Ribosomopathies
Ribosomopathies are diseases caused by mutations in ribosomal proteins or assembly factors, often leading to impaired ribosome function. Defects in ribosome-associated quality control may exacerbate the accumulation of aberrant proteins, contributing to disease pathology. Understanding the interplay between ribosome biogenesis and quality control is crucial for developing treatments.
From ribosome-associated ubiquitin-dependent protein catabolic process-Related Genes to Experimental Models
| Research Question | Suitable Model |
|---|---|
| What is the role of LTN1 in ubiquitinating nascent chains? | LTN1 knockout cell line |
| How does VCP mutation affect protein degradation? | VCP point mutation knock-in |
| Can we visualize RQC in live cells? | Tagged knock-in of RQT2 with fluorescent protein |
| What is the effect of RQC overload? | Overexpression of aberrant mRNA substrate |
| Which genes are essential for RQC? | CRISPR library screening |
| How does RQC change in disease? | Patient-derived iPSCs with mutations |
How to Study the ribosome-associated ubiquitin-dependent protein catabolic process Process
| Method | What It Measures | Typical Application |
|---|---|---|
| Ribo-seq | Ribosome occupancy and collisions | Identify stalled ribosomes and RQC substrates |
| RNA-seq | Transcriptional changes | Assess gene expression upon RQC perturbation |
| Proteomics | Protein abundance and ubiquitination | Identify degradation intermediates |
| Co-IP | Protein-protein interactions | Study RQC complex assembly |
| CRISPR screens | Gene essentiality and synthetic lethality | Discover novel RQC factors |
| Polysome profiling | Translation efficiency | Measure global translation changes |
| Ubiquitin pulldown | Ubiquitinated proteins | Enrich ubiquitinated nascent chains |
Ribosome Profiling (Ribo-seq)
Ribo-seq provides a snapshot of ribosome positions on mRNAs, allowing detection of stalled ribosomes and collided disomes. This method is crucial for identifying endogenous substrates of ribosome-associated quality control.
RNA Sequencing (RNA-seq)
RNA-seq measures changes in gene expression upon perturbation of RQC components, revealing transcriptional responses and potential compensatory pathways.
Proteomics
Mass spectrometry-based proteomics can identify ubiquitinated proteins and their degradation products, providing insights into the specificity of the pathway.
Imaging
Fluorescence microscopy with tagged ribosomal proteins and nascent chains allows visualization of ribosome collisions and quality control factor recruitment in real time.
How CRISPR Can Be Used to Study GO:1990116 ribosome-associated ubiquitin-dependent protein catabolic process
Knockout
CRISPR knockout of core RQC genes such as LTN1, RQT2, or CDC48 allows researchers to assess their essentiality and effects on protein homeostasis [1,2,4]. Knockout cell lines can be used to identify substrates that accumulate upon pathway disruption.
Point Mutation
Introducing point mutations in genes like VCP (e.g., disease-associated mutations) via CRISPR can model human diseases and dissect the molecular mechanisms of RQC. Point mutations can also be used to study the catalytic activity of ubiquitin ligases.
Knock-in
Knock-in of tagged versions of RQC components (e.g., GFP-RQT2) enables live-cell imaging and proteomic analysis of the complex. Knock-in of substrate reporters allows monitoring of degradation in real time.
Overexpression
Overexpression of aberrant mRNA substrates or RQC components can overload the pathway, revealing its capacity and regulation. This approach is useful for studying the consequences of proteotoxic stress.
How EDITGENE Supports ribosome-associated ubiquitin-dependent protein catabolic process Research
Researchers studying ribosome-associated ubiquitin-dependent protein catabolic process-related genes often need to determine whether a candidate gene is causally involved in the pathway or merely correlated with its activity. EDITGENE provides a comprehensive suite of CRISPR services to enable precise genetic manipulation and functional interrogation of these genes.
Contact EDITGENE today to design your custom CRISPR model for ribosome-associated ubiquitin-dependent protein catabolic process research.
Frequently Asked Questions About ribosome-associated ubiquitin-dependent protein catabolic process
What is GO:1990116?
GO:1990116 is the Gene Ontology term for ribosome-associated ubiquitin-dependent protein catabolic process, which describes the degradation of aberrant nascent polypeptides associated with stalled ribosomes.
What genes are involved in ribosome-associated ubiquitin-dependent protein catabolic process?
Key genes include RQT2, RQT3, RQT4, LTN1, CDC48 (VCP), NEMF, and TCF25, among others [1,2,4].
How does ribosome-associated quality control work?
It involves ribosome stalling, collision, RQT complex-mediated splitting, ubiquitination of the nascent chain, extraction by Cdc48/p97, and proteasomal degradation [1,2,4].
What diseases are linked to defects in this pathway?
Neurodegenerative diseases like ALS and IBMPFD, as well as cancer and ribosomopathies, have been linked to defects in this pathway [1,4].
What is the role of Cdc48/p97 in ribosome-associated degradation?
Cdc48/p97 is an ATPase that extracts ubiquitinated nascent chains from the ribosome for proteasomal degradation.
How can CRISPR be used to study ribosome-associated quality control?
CRISPR knockout, point mutation, knock-in, and overexpression models allow precise manipulation of RQC genes to study their functions and interactions [1,2,3,4].
What methods are used to study ribosome-associated ubiquitin-dependent protein catabolic process?
Common methods include Ribo-seq, RNA-seq, proteomics, imaging, and CRISPR screens [1,2].
What is the RQT complex?
The RQT complex is a ribosome quality control trigger complex that dissociates collided ribosomes in an ATP-dependent manner.
How is the degradation of premature termination products mediated?
Premature termination products, such as Orf1p from ODC antizyme mRNA, are degraded via ribosome-associated quality control involving ubiquitination and proteasomal degradation.
Why is ribosome-associated quality control important for cellular health?
It prevents the accumulation of toxic truncated proteins, maintaining proteostasis and cellular function.
Conclusion
The ribosome-associated ubiquitin-dependent protein catabolic process (GO:1990116) is a critical quality control pathway that safeguards proteostasis by eliminating aberrant nascent polypeptides. Its molecular players, including the RQT complex, LTN1, and Cdc48/p97, are essential for recognizing and degrading stalled translation products [1,2,4]. Dysregulation of this pathway is linked to severe human diseases, underscoring its importance in health and disease [1,3]. Continued research using advanced CRISPR models and multi-omics approaches will further illuminate its mechanisms and therapeutic potential.
References
- 1. Ford PW et al.. 2024. Ubiquitin-dependent translation control mechanisms: Degradation and beyond.. Cell Rep 43(12):115050 PMID: 39661518
- 2. Matsuo Y et al.. 2020. RQT complex dissociates ribosomes collided on endogenous RQC substrate SDD1.. Nat Struct Mol Biol 27(4):323-332 PMID: 32203490
- 3. Pradhan AK et al.. 2021. Ribosome-associated quality control mediates degradation of the premature translation termination product Orf1p of ODC antizyme mRNA.. FEBS Lett 595(15):2015-2033 PMID: 34109626
- 4. Verma R et al.. 2013. Cdc48/p97 promotes degradation of aberrant nascent polypeptides bound to the ribosome.. Elife 2:e00308 PMID: 23358411
