RPS20 Human
Description
Molecular Structure and Gene Organization
RPS20 is a 142-amino acid (aa) protein belonging to the uS10 family of ribosomal proteins. It is localized to the cytoplasm and integrated into the head region of the 40S ribosomal subunit, interacting with ribosomal proteins uS3 and uS14 during assembly . The RPS20 gene is located on chromosome 8 and co-transcribed with the U54 small nucleolar RNA (snoRNA) within its second intron . Multiple processed pseudogenes for RPS20 exist in the human genome, a common feature of ribosomal protein genes .
Colorectal Cancer (CRC):
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Disruptive mutations in RPS20 (e.g., frameshifts, missense substitutions) are linked to hereditary non-polyposis CRC .
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Haploinsufficiency impairs ribosome biogenesis, increasing cancer risk .
Renal Cell Carcinoma (RCC):
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Overexpression in RCC tissues correlates with aggressive phenotypes (proliferation, migration, invasion) .
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Knockdown reduces CDK4, cyclin D1, and N-cadherin while increasing E-cadherin, indicating epithelial-mesenchymal transition (EMT) inhibition .
| RPS20 Expression in RCC | Outcome | Source |
|---|---|---|
| High expression in tumors | Enhanced proliferation, invasion | |
| Knockdown in 786-O/OS-RC-2 cells | Reduced tumor growth in vivo |
Translatome Reorganization Under Ribosomal Shortage
RPS20 deficiency in HEK293T cells induces selective translation of mRNAs with:
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Higher abundance
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Lower GC content
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Longer coding sequences
This reorganization prioritizes essential cellular proteins under stress .
Signaling Pathway Modulation
Ubiquitination Dynamics
RPS20 ubiquitination is reversible:
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Induction: Triggered by ribosome stalling (e.g., anisomycin treatment) .
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Resolution: Mediated by deubiquitinating enzymes (e.g., OTUD3, USP21) .
Protein Interactions and Network Analysis
RPS20 interacts with other ribosomal proteins and non-ribosomal factors:
| Partner | Interaction Context | Confidence Score | Source |
|---|---|---|---|
| RPL18A | 60S subunit assembly | 0.999 | |
| RPS3 | DNA repair and ribosome function | 0.999 | |
| ZNF598 | RQC pathway initiation | 0.999 | |
| OTUD3 | Deubiquitination in RQC | 0.999 |
Tissue-Specific Expression Patterns
RPS20 is ubiquitously expressed but enriched in tissues with high translational activity:
Product Specs
Q&A
What is the role of RPS20 in ribosome biogenesis, and how do mutations disrupt this process?
RPS20 (uS10) is a structural component of the 40S ribosomal subunit critical for ribosome assembly and mRNA translation fidelity. It interacts with 18S rRNA, uS3, and uS14 during the late stages of 40S subunit maturation, particularly during the release of assembly factors like ENP1 and LTV1 . Mutations in RPS20 (e.g., p.Ile84Asn/Ser) destabilize ribosomal architecture by disrupting hydrophobic interactions at conserved residues, impairing 18S rRNA processing and reducing polysome formation . Methodologically, ribosome profiling via sucrose gradient centrifugation and cryo-EM structural analysis (e.g., PDB ID 6EK0) are essential for mapping defects in subunit assembly .
How are RPS20 mutations linked to Diamond-Blackfan anemia (DBA) and colorectal cancer (CRC)?
Germline RPS20 mutations are pleiotropic, causing DBA in pediatric patients and increasing CRC risk in adults. For example, de novo missense variants (p.Ile84Asn/Ser) reduce RPS20 protein levels by 50–70%, leading to erythroid precursor apoptosis in DBA . Conversely, frameshift mutations (p.Val50Serfs*23) predispose to early-onset CRC through mechanisms independent of classical microsatellite instability . Researchers should employ longitudinal clinical tracking (Table 1) coupled with exome sequencing to distinguish tissue-specific phenotypes.
Table 1: Clinical Features of RPS20 Mutation Carriers
| Feature | DBA Phenotype (BMF92) | CRC Phenotype (Nieminen et al., 2014) |
|---|---|---|
| Age at Onset | Neonatal anemia | Median 52 years (CRC diagnosis) |
| Key Laboratory Findings | Elevated erythrocyte adenosine deaminase | Microsatellite stable tumors |
| Congenital Anomalies | None | None |
| Family History | Negative | Autosomal dominant CRC predisposition |
What methodologies are optimal for studying RPS20 dysfunction in cellular models?
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Western blotting: Quantify RPS20 protein levels in lymphoblastoid cell lines (LCLs) using antibodies like α-RPS20 (Abcam ab133776) .
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Yeast complementation assays: Introduce human RPS20 variants into Saccharomyces cerevisiae to assess growth defects and rRNA processing (e.g., 18S/25S ratio) .
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Polysome profiling: Evaluate ribosome distribution shifts in mutant cells, such as reduced 80S peaks and polysome/60S ratios .
How do RPS20 mutations mechanistically drive colorectal carcinogenesis despite intact microsatellite stability?
Unlike RPL22 mutations in microsatellite-unstable CRC, RPS20-linked CRC involves transcriptome reorganization favoring oncogenic pathways. RNA-seq in HEK293T cells expressing mutant RPS20 reveals upregulated Wnt/β-catenin signaling and epithelial-mesenchymal transition (EMT) genes . Prioritize CRISPR-Cas9 knock-in models combined with ribo-seq to identify translationally dysregulated mRNAs (e.g., MYC, CCND1).
How can researchers resolve contradictions between in vitro and in vivo phenotypes of RPS20 variants?
Discrepancies arise from tissue-specific haploinsufficiency thresholds. For example, 50% RPS20 reduction causes anemia in hematopoietic cells but requires secondary hits (e.g., APC mutations) for CRC . Use conditional knockout mice with Cre-lox systems to dissect tissue-specific effects, and integrate proteomics to identify compensatory ribosomal proteins (e.g., RPS3, RPS29) .
What strategies validate the pathogenicity of novel RPS20 variants in understudied populations?
Apply a multi-tiered framework:
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Computational prediction: Use REVEL, CADD, and PhyloP to assess evolutionary conservation and deleteriousness .
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Functional assays: Transient overexpression in 293T cells to test protein stability (Figure 2E) .
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Clinical correlation: Compare variant carriers against the DBA Registry (NCT00027274) for penetrance estimates .
Table 2: Functional Assays for RPS20 Variant Classification
| Assay Type | Outcome Measure | Pathogenic Threshold |
|---|---|---|
| Protein stability | RPS20/β-actin ratio by Western | <60% of wild-type levels |
| Ribosome assembly | 18S rRNA processing efficiency | >30% reduction vs. controls |
| Yeast growth | Colony size at 37°C | ≥50% growth inhibition |
How does RPS20 deficiency reshape the translatome in proliferating cells?
RPS20 haploinsufficiency preferentially translates mRNAs with upstream ORFs (uORFs) or IRES elements, such as ATF4 and VEGF, via altered ribosome scanning dynamics . Employ ribosome footprinting with cycloheximide arrest to map codon-resolution translation changes. Cross-reference with CRISPR interference screens to identify synthetic lethal partners (e.g., RQC pathway genes) .
Why are some RPS20 mutations associated with DBA but not cancer, and vice versa?
Tissue-specific vulnerability stems from divergent ribosomal stress responses. Erythroid progenitors undergo TP53-mediated apoptosis under RPS20 deficiency, whereas intestinal crypt cells activate NF-κB survival pathways . Use organoid models to compare stress signaling across tissues, and single-cell RNA-seq to profile TP53 vs. NF-κB activity in mutant lineages.
Methodological Recommendations
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For structural studies: Cryo-EM reconstruction of mutant 40S subunits (≤3.5 Å resolution) to identify displacement of rRNA domains .
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For in vivo modeling: Zebrafish rps20 mutants generated via morpholino knockdown to recapitulate anemia and developmental defects .
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Data integration: Leverage the ClinVar database (RCV000486050) for variant classification and the COSMIC database for somatic mutation patterns .
Product Science Overview
Ribosomal Protein S20 (RPS20) is a crucial component of the small 40S subunit of the ribosome, which plays a vital role in the synthesis of proteins within the cell. This protein is encoded by the RPS20 gene and is part of the S10P family of ribosomal proteins . The human recombinant form of RPS20 is produced through recombinant DNA technology, allowing for its use in various research and therapeutic applications.
Ribosomes are complex molecular machines composed of ribosomal RNA (rRNA) and ribosomal proteins. They are responsible for translating messenger RNA (mRNA) into proteins. The small 40S subunit, which includes RPS20, binds to the mRNA and decodes its sequence, while the large 60S subunit catalyzes the formation of peptide bonds between amino acids .
RPS20 is one of the primary rRNA binding proteins. It binds directly to the 16S rRNA, nucleating the assembly of the bottom of the body of the 30S subunit by interacting with several RNA helices of the 16S rRNA . This interaction is essential for the proper assembly and function of the ribosome.
The RPS20 gene is located on chromosome 8 in humans and is co-transcribed with the small nucleolar RNA gene U54, which is located in its second intron . As is typical for genes encoding ribosomal proteins, there are multiple processed pseudogenes of RPS20 dispersed throughout the genome .
RPS20 is expressed in various tissues, including lymphoid tissue, bone marrow, testis, and skeletal muscle . Its expression is crucial for cell proliferation, protein ubiquitination, and the innate immune response .
Mutations in the RPS20 gene have been associated with several diseases, including Diamond-Blackfan Anemia and Familial Colorectal Cancer Type X . Diamond-Blackfan Anemia is a rare genetic disorder characterized by a failure to produce enough red blood cells, leading to anemia. Familial Colorectal Cancer Type X is a hereditary condition associated with an increased risk of developing colorectal cancer.
The human recombinant form of RPS20 is produced using recombinant DNA technology, which involves inserting the RPS20 gene into a suitable expression system, such as bacteria or yeast, to produce the protein in large quantities. This recombinant protein can be used in various research applications, including studies on ribosome assembly, protein synthesis, and the role of ribosomal proteins in disease.
Additionally, recombinant RPS20 can be used in therapeutic applications, such as the development of treatments for diseases associated with mutations in the RPS20 gene. By understanding the structure and function of RPS20, researchers can develop targeted therapies to correct or compensate for the effects of these mutations.
