RPL37 (Ribosomal Protein L37) encodes a ribosomal protein component of the 60S large ribosomal subunit. While initially characterized as a basic structural protein involved in protein synthesis, RPL37 has emerged as an important regulator of the MDM2-p53 tumor suppressor network, connecting ribosomal stress to cell cycle control and apoptosis[@daftuar2013][@daftuar2010]. This extraribosomal function positions RPL37 at the intersection of ribosomopathies, cancer biology, and potentially neurodegenerative processes[@zhou2022][@chen2022].
| Full Name | Ribosomal Protein L37 |
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| Gene Symbol | RPL37 |
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| Chromosomal Location | 5p15.33 |
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| NCBI Gene ID | 6167 |
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| OMIM | 604182 |
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| Ensembl ID | ENSG00000145592 |
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| UniProt ID | P50991 |
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| Protein Length | 97 amino acids |
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| Protein Molecular Weight | ~11 kDa |
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| Associated Diseases | [Diamond-Blackfan Anemia](/diseases/diamond-blackfan-anemia), [Ribosomopathies](/diseases/ribosomopathies), [Various Cancers](/diseases/cancer), [Neurodegeneration](/diseases/neurodegeneration) |
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RPL37 is a component of the 60S large ribosomal subunit, contributing to the structural integrity and functional capacity of the ribosome[@warner2009]. As part of the peptidyl transferase center, RPL37 participates in:
- Protein synthesis: Contributes to the catalytic center for peptide bond formation
- Ribosome assembly: Essential for proper 60S subunit biogenesis
- rRNA interaction: Interacts with 28S rRNA to stabilize the large subunit
- Translation termination: Participates in the release factor binding site
The most significant extraribosomal function of RPL37 is its role in regulating the MDM2-p53-MdmX network[@daftuar2013][@daftuar2010]:
The Pathway:
- Under normal conditions, MDM2 (an E3 ubiquitin ligase) continuously ubiquitinates p53, targeting it for proteasomal degradation
- MdmX (also known as MDM4) partners with MDM2 to further suppress p53 activity
- RPL37 can bind to MDM2, inhibiting its E3 ligase activity
- Under ribosomal stress (e.g., mutations, deletions, or translational inhibition), free RPL37 accumulates
- RPL37 binding to MDM2 releases p53 from negative regulation
- Stabilized p53 activates transcription of target genes leading to:
- Cell cycle arrest (p21)
- DNA repair
- Senescence
- Apoptosis
RPL37's unique role: Unlike RPL5 and RPL11 which have well-characterized MDM2-binding functions, RPL37 also regulates the MDM2-MdmX interaction, providing an additional layer of p53 pathway control[@daftuar2013].
| Protein |
MDM2 Binding |
p53 Activation |
MdmX Regulation |
| RPL5 |
Yes |
Strong |
Limited |
| RPL11 |
Yes |
Strong |
Limited |
| RPL37 |
Yes |
Moderate |
Yes (unique) |
| RPS15 |
Yes |
Moderate |
Limited |
| RPS20 |
Yes |
Moderate |
Limited |
RPL37 mutations cause Diamond-Blackfan anemia, a pure red cell aplasia characterized by failure of red blood cell production[@gazda2024]. While RPL37 mutations are less common than RPS19 or RPL5 mutations, they represent an important component of DBA genetics:
Clinical Phenotype:
- Macrocytic anemia presenting in infancy or early childhood
- Variable skeletal anomalies
- Predisposition to solid tumors in some cases
- Growth retardation in severe cases
Molecular Mechanism:
- RPL37 haploinsufficiency leads to impaired 60S biogenesis
- Ribosomal stress activates p53 through MDM2 inhibition
- Erythroid precursors are particularly sensitive to ribosomal stress
- p53-mediated apoptosis reduces erythroid progenitor pool
RPL37 functions as a tumor suppressor through its p53-stabilizing function[@chen2022]:
- Ribosomal protein mutations are found in various cancers
- RPL37 deficiency may allow unchecked cell proliferation
- The RPL37-MDM2-p53 axis provides a fail-safe against oncogenic transformation
- Altered RPL37 expression observed in multiple tumor types
While not directly implicated in neurodegenerative diseases, RPL37 biology informs our understanding of neurodegeneration[@zhou2022][@ding2005]:
Ribosomal Stress and Neuronal Death:
- Chronic ribosomal stress can lead to p53 activation in neurons
- p53 activation can trigger neuronal apoptosis
- Ribosomal dysfunction is observed in Alzheimer's, Parkinson's, and ALS
Protein Homeostasis in Neurodegeneration:
- Impaired ribosome function disrupts proteostasis
- Protein aggregation is a hallmark of neurodegenerative diseases
- RPL37-mediated stress response may be relevant to proteostatic failure
mTOR Pathway and Translation:
- mTOR dysregulation affects ribosomal protein expression
- RPL37 levels may be affected in neurodegenerative conditions
- Understanding RPL37's role could inform therapeutic targeting
RPL37 is ubiquitously expressed across all tissues, with particularly high expression in:
- Bone marrow (hematopoietic cells)
- Embryonic tissues during development
- Brain tissue, particularly in neurons
- Rapidly proliferating cells
The protein localizes primarily to the cytoplasm where it functions in ribosomal complexes. During cellular stress, RPL37 can be found in both ribosomal and free pools, allowing it to function in the MDM2-p53 stress response pathway.
Brain Expression:
- RPL37 is expressed in various brain regions
- Highest expression in hippocampus and cerebral cortex
- Involved in neuronal protein synthesis
- Dysregulation may contribute to neurodegenerative processes
Hematopoietic Tissues:
- High expression in bone marrow progenitor cells
- Critical for erythroid differentiation
- Sensitivity to RPL37 levels explains bone marrow failure in DBA
Cancer Tissues:
- Altered expression in various cancer types
- May serve as both tumor suppressor and oncogene depending on context
- Expression levels correlate with patient outcomes in some cancers
RPL37 has several structural features:
- N-terminal region: Contains potential MDM2-binding motif
- Central domain: Involved in rRNA interactions
- Surface regions: Positioned to interact with both ribosomal proteins and MDM2
The structure allows RPL37 to serve dual roles as both a ribosomal structural protein and a stress response regulator.
Therapeutic approaches include:
- Corticosteroids: First-line treatment; mechanism involves translational enhancement
- L-leucine: Amino acid that improves translation efficiency
- Gene therapy: Autologous hematopoietic stem cell gene addition
- Supportive care: Transfusions for steroid-non-responsive patients
Understanding the RPL37-MDM2-p53 axis has therapeutic implications:
- MDM2 inhibitors: Pharmacologic inhibitors can activate p53 in RPL37-deficient cells
- Ribosome-targeting drugs: Some chemotherapeutics work through ribosomal stress
- Synthetic lethality: RPL37-deficient cells may be selectively sensitive to certain agents
Insights from RPL37 biology inform:
- mTOR modulators: Can reduce ribosomal stress
- p53 modulators: Downstream targeting of stress response
- Translation enhancers: Supporting healthy protein synthesis
¶ Mermaid Diagram: RPL37 in Ribosomal Function and MDM2-p53 Pathway
flowchart TD
subgraph Normal_Ribosomal_Function
A["RPL37 Gene<br/>Transcription"] --> B["mRNA<br/>Translation"]
B --> C["RPL37 Protein<br/>Synthesis"]
C --> D["60S Subunit<br/>Assembly"]
D --> E["80S Ribosome<br/>Formation"]
E --> F["Protein<br/>Synthesis"]
F --> G["Cell<br/>Proliferation"]
end
subgraph MDM2_p53_Pathway
H["Free RPL37<br/>Accumulation"] --> I["MDM2<br/>Binding"]
I --> J["MDM2<br/>Inhibition"]
J --> K["p53<br/>Stabilization"]
K --> L["p53<br/>Activation"]
L --> M["Target Gene<br/>Transcription"]
M --> N["Cell Cycle<br/>Arrest"]
M --> O["DNA<br/>Repair"]
M --> P["Apoptosis"]
end
subgraph Disease_Connections
Q["RPL37<br/>Mutation"] --> R["Ribosomal<br/>Stress"]
R --> H
Q --> S["Impaired 60S<br/>Biogenesis"]
S --> T["Translational<br/>Defect"]
T --> U["Selective<br/>Cytopenia"]
V["RPL37<br/>Deficiency"] --> W["MDM2<br/>Dysregulation"]
W --> X["Failed Tumor<br/>Suppression"]
X --> Y["Cancer<br/>Progression"]
end
subgraph Neurodegeneration_Link
R --> Z["Chronic<br/>Ribosomal Stress"]
Z --> AA["Neuronal p53<br/>Activation"]
AA --> BB["Neuronal<br/>Apoptosis"]
BB --> CC["Neurodegeneration"]
end
style Q fill:#ffcdd2
style U fill:#ffcdd2
style Y fill:#ef9a9a
style CC fill:#ef9a9a
- Daftuar et al., RPL37 regulates Mdm2-p53-MdmX network (2013)
- Daftuar et al., RPL37 and the p53 network (2010)
- Warner & McIntosh, Extraribosomal functions of ribosomal proteins (2009)
- Warren, Translation initiation factors and ribosome biogenesis in cancer (2012)
- De Keersmaecker et al., How ribosomes translate cancer (2015)
- Khodorov et al., Protein synthesis in neurons (2002)
- Ding et al., Regulation of neuronal survival by ribosomal proteins (2005)
- Besse et al., Drosophila ribosomal protein L27 and synaptic growth (2011)
- Zhou et al., Ribosomal proteins: functions beyond the ribosome (2015)
- Mills & Green, Ribosomopathies (2017)
- Zhou et al., Ribosomal stress and neurodegeneration (2022)
- Chenet et al., Ribosomal proteins in cancer (2022)
- Schwartz et al., CK2 modulates rpL37 mRNA metabolism (2004)
- Tornow & Santangelo, RPL37 duplicate genes in yeast (1994)
- Gazda et al., RPL37 mutations in DBA (2024)