PSME1 antibodies are immunoreagents designed to detect the PA28α subunit of the PA28 proteasome activator complex. This complex enhances proteasomal cleavage efficiency, generating peptides for MHC class I antigen presentation . Key features include:
PSME1 antibodies are validated for:
Prostate Cancer: Elevated PSME1 expression in primary/metastatic tumors correlates with poor prognosis. Anti-PSME1 antibodies localize to tumor vasculature and perivascular regions in xenografts .
Multiple Myeloma: PSME1-targeting antibodies enhance T-cell cytotoxicity by diversifying the MHC-I immunopeptidome .
Gastric Cancer: High PSME1 expression associates with improved survival and immune infiltration .
Antibody-Drug Conjugates: Anti-PSME1 antibodies selectively deliver payloads to prostate tumors in vivo .
Immunoproteasome Activation: Compound A (a PSME1/PSME2 agonist) amplifies antigen presentation, sensitizing tumors to T-cell therapies .
Prostate Cancer: PSME1 overexpression in tumor stroma and metastases correlates with advanced disease .
Soft Tissue Sarcomas: High PSME1 levels predict poor metastasis-free survival .
Contradictory Roles: While linked to worse outcomes in prostate cancer and melanoma, PSME1 upregulation associates with better survival in gastric cancer .
Dilution Optimization: Titration is critical for IHC/WB to avoid background noise .
Cross-Reactivity: Most antibodies recognize human, mouse, and rat PSME1 but may show species-specific variability .
Storage: Stable at -20°C in glycerol-containing buffers; avoid freeze-thaw cycles .
PSME1, also known as PA28 alpha or REG-alpha, is a subunit of the proteasome activator complex that regulates intracellular proteolytic pathways mediated by the proteasome. The principal function of the proteasome is targeted degradation of intracellular proteins, with the 20S proteasome activity controlled by regulatory complexes that bind to the ends of the cylindrical proteasome . PSME1 is part of the 11S regulator (REG or PA28), a complex of 28 kDa subunits that activates proteasomes toward the production of antigenic peptides .
PSME1 is essential for efficient processing of antigens and for assembly of the immunoproteasome, acting as a critical component in the immune response by facilitating the generation of tumor antigens presented by MHC class I molecules . Antigen presenting cells and many other cell types express PSME1 under the control of interferon gamma, highlighting its important role in immunity and inflammation .
Commercial PSME1 antibodies are available in both polyclonal and monoclonal formats, each with specific applications and characteristics. Key specifications include:
Polyclonal Antibody (e.g., 10543-1-AP):
Applications: Western Blot (WB), Immunohistochemistry (IHC), ELISA
Reactivity: Human, mouse, rat
Molecular Weight Detection: 29-33 kDa
Recommended Dilutions:
Application | Dilution |
---|---|
Western Blot (WB) | 1:500-1:1000 |
Immunohistochemistry (IHC) | 1:50-1:500 |
Monoclonal Antibody (e.g., AB02/4C4):
Clone: AB02/4C4
Isotype: IgG1
Format: Purified
Western Blotting: Detects a band of approximately 31 kDa in MCF-7 cell lysates
For optimal results, it is recommended that these antibodies be titrated in each testing system as performance can be sample-dependent .
In normal immune function, PSME1 facilitates antigen processing and presentation through the proteasome system. It plays a key role in generating peptides for MHC class I presentation, which is crucial for T-cell recognition and immune surveillance .
In disease states, PSME1 shows altered expression patterns with significant implications:
Viral Infections:
Cancer:
These disease associations highlight PSME1's potential as both a biomarker and therapeutic target.
PSME1 plays a significant role in HBV replication through direct interaction with the HBV core protein (HBc). Research has identified PSME1 as an adjacent protein of HBc through proteomic analysis using engineered ascorbate peroxidase (APEX2) biotinylation followed by mass spectrometry .
Mechanistically, PSME1:
Affects HBc stability and accumulation
Protects HBc from proteasomal degradation
Influences viral replication through HBc stabilization
Experimental evidence demonstrates that PSME1 knockdown in HBV-infected HepG2-NTCP cells leads to:
Decreased HBeAg and HBsAg levels in cell culture supernatants
Reduced total HBV RNA and pregenomic RNA (pgRNA)
Decreased HBc expression
Significantly lower HBV relaxed circular DNA (rcDNA) copy number
Mechanistically, PSME1 deficiency causes:
These findings suggest PSME1 inhibition as a potential therapeutic strategy for HBV-related diseases.
Based on the literature, several methodological approaches have proven effective for studying PSME1 interactions with viral proteins:
Proximity-based Labeling with Mass Spectrometry:
RNA Interference:
Co-immunoprecipitation Assays:
Viral Infection Models:
These approaches allow for comprehensive characterization of PSME1's role in viral protein stability and viral replication.
PSME1 has emerged as a significant factor in cancer progression with potential as a biomarker across multiple cancer types:
Soft Tissue Leiomyosarcoma:
Esophageal Squamous Cell Carcinoma:
Prostate Cancer:
The mechanisms by which PSME1 contributes to cancer progression likely involve:
Altered proteasomal activity affecting protein homeostasis
Changes in antigen presentation that may help cancer cells evade immune surveillance
Potential influence on cell cycle regulation and apoptotic pathways
For biomarker applications, PSME1 expression can be assessed through:
Immunohistochemistry of tumor tissues
Protein expression analysis via Western blotting
Gene expression profiling
Potential assessment in liquid biopsies
Further research is needed to standardize PSME1 assessment methods and establish clinically relevant thresholds for different cancer types.
For optimal Western blotting results with PSME1 antibodies, researchers should consider the following conditions:
Sample Preparation:
PSME1 is detected in various samples including mouse spleen tissue, A431 cells, RAW 264.7 cells, and MCF-7 cell lysates
Expected molecular weight: 29-33 kDa (polyclonal antibody) or approximately 31 kDa (monoclonal antibody)
Protocol Recommendations:
Dilution:
Buffer System: PBS with 0.02% sodium azide and 50% glycerol pH 7.3 is commonly used for antibody storage
Storage: Store at -20°C for stability (up to one year after shipment)
Sample Loading: 20-30 μg of total protein per lane is typically sufficient
Controls: Include positive controls such as mouse spleen tissue or A431 cell lysates
Troubleshooting Tips:
If background is high, increase blocking time or adjust antibody dilution
If signal is weak, consider longer exposure times or increase antibody concentration
For cross-reactivity issues, more stringent washing steps may be necessary
Optimization is crucial as antibody performance can be sample-dependent, so titration is recommended in each testing system to obtain optimal results .
Designing experiments to study PSME1's role in antigen processing and presentation requires a comprehensive approach:
Genetic Manipulation Strategies:
CRISPR-Cas9 knockout or knockdown of PSME1 using shRNA/siRNA
Overexpression studies with tagged PSME1 constructs
Generation of mutant PSME1 variants to identify functional domains
Functional Assays:
Measure proteasome activity using fluorogenic substrates in PSME1-modified cells
Assess MHC class I surface expression by flow cytometry
Perform antigen presentation assays with model antigens
Conduct T cell activation assays to measure functional consequences
Biochemical Analysis:
Immunoprecipitation to study PSME1 interactions with proteasome components
Western blotting to assess expression levels of PSME1 and related proteins
Mass spectrometry to identify peptides generated in the presence/absence of PSME1
Imaging Approaches:
Immunofluorescence to visualize PSME1 localization
Live cell imaging with fluorescently tagged PSME1 to track dynamics
Proximity ligation assays to confirm protein-protein interactions in situ
Validation in Relevant Models:
Use antigen presenting cells (dendritic cells, macrophages)
Employ interferon-γ treatment to upregulate PSME1 and immunoproteasome components
Consider three-dimensional organoid cultures or in vivo models for physiological relevance
Control conditions should include appropriate isotype controls for antibody experiments and careful selection of housekeeping genes for expression normalization in qPCR studies.
When implementing PSME1 knockdown studies in viral infection models, researchers should consider several critical factors:
Knockdown Strategy Selection:
Cell Model Considerations:
Infection Parameters:
Optimize viral multiplicity of infection (MOI)
Determine appropriate timepoints for analysis post-infection
Include appropriate controls (mock-infected, non-targeting shRNA)
Assessment of Viral Markers:
Cell Viability and Function Controls:
Additional Considerations:
Evaluate the effect on proteasome function using activity assays
Consider rescue experiments by re-expressing shRNA-resistant PSME1
Investigate protein-protein interactions between PSME1 and viral proteins
The research by Liu et al. demonstrated that PSME1 knockdown in HBV-infected HepG2-NTCP cells led to significant decreases in HBeAg and HBsAg levels, reduced HBV RNA, decreased HBc expression, and lower HBV rcDNA copy numbers, providing a methodological framework for such studies .
Different PSME1 antibody applications demonstrate varying levels of sensitivity and specificity that researchers should consider when designing experiments:
Western Blotting (WB):
Sensitivity: Typically detects PSME1 at concentrations of 20-30 μg of total protein
Specificity: Polyclonal antibodies (10543-1-AP) detect bands at 29-33 kDa
Positive Controls: Mouse spleen tissue, A431 cells, RAW 264.7 cells
Applications: Protein expression levels, post-translational modifications, interaction studies
Immunohistochemistry (IHC):
Sensitivity: Can detect PSME1 in tissue sections with appropriate antigen retrieval
Specificity: May show background in certain tissues; optimization crucial
Antigen Retrieval: Suggested with TE buffer pH 9.0 or citrate buffer pH 6.0
Applications: Tissue localization, expression patterns in pathological samples
ELISA:
Sensitivity: Generally higher than WB or IHC for quantitative assessment
Specificity: Dependent on antibody pair selection and optimization
Applications: Quantitative measurement in serum or cell culture supernatants
Immunoprecipitation (IP):
Sensitivity: Variable depending on protein abundance and antibody affinity
Specificity: Higher specificity due to enrichment of target protein
Applications: Protein-protein interaction studies, post-translational modification analysis
Each application requires specific optimization strategies, and researchers should select the appropriate technique based on their experimental questions, sample types, and required sensitivity/specificity balance.
Interpreting gene expression data for PSME1 across different experimental platforms requires careful consideration of several potential pitfalls:
Platform Variation:
Different microarray platforms may use distinct probe sequences that can affect sensitivity and specificity
Human cDNA platforms (like those used in the vaccinia study) versus oligo array platforms (used in yellow fever studies) may show systematic differences
RNA-seq versus microarray technologies may yield different absolute expression values
Probe Identity and Annotation Issues:
Statistical Analysis Considerations:
Normalization Methods:
Biological Variation:
Technical Validation:
Confirmation with alternative methods (RT-qPCR, Western blotting) is essential
Discrepancies between mRNA and protein levels should be investigated
To address these pitfalls, researchers should:
Clearly document platform specifications and analysis methods
Use multiple technical and biological replicates
Validate findings with orthogonal techniques
Consider meta-analysis approaches when comparing across studies
Be cautious when interpreting results from heterogeneous patient populations
Based on emerging research, PSME1 offers several promising avenues for developing novel antiviral strategies, particularly for HBV:
Targeting PSME1-HBc Interactions:
Research has established that PSME1 interacts with HBV core protein (HBc) and affects viral replication
Small molecule inhibitors or peptide mimetics could be designed to disrupt this interaction
Structure-based drug design approaches using crystallography data of the PSME1-HBc interface would be valuable
Modulating PSME1 Expression or Activity:
RNA interference approaches targeting PSME1 have shown efficacy in reducing HBV replication in vitro
Studies demonstrated that PSME1 knockdown decreased HBeAg and HBsAg levels, reduced viral RNA, and lowered rcDNA copy numbers
Translating these findings to therapeutic RNAi strategies could be promising
Exploiting Proteasomal Degradation Pathways:
PSME1 deficiency leads to increased ubiquitination and proteasomal degradation of HBc
Compounds that selectively enhance HBc ubiquitination or its interaction with the 26S proteasome could mimic this effect
Screening for small molecules that modulate PSME1's protective effect on HBc could identify lead compounds
Combination Therapy Approaches:
PSME1-targeting strategies could be combined with existing antivirals
Since PSME1 affects viral replication through a distinct mechanism, this might address resistance issues
Potential synergistic effects with nucleos(t)ide analogues or other HBV therapies
Translational Research Considerations:
Clinical Development Pathway:
Assess safety concerns related to PSME1 inhibition on normal proteasome function
Consider liver-specific delivery strategies to minimize systemic effects
Develop companion diagnostics to identify patients most likely to benefit
The discovery that PSME1 inhibition decreases HBV replication through accelerated HBc degradation represents "a promising new therapeutic approach for treating diseases linked to HBV" , and translating these findings into clinical applications is a logical next step in antiviral development.
When encountering inconsistent results with PSME1 antibodies in Western blot applications, researchers should consider the following troubleshooting strategies:
Sample Preparation Issues:
Problem: Degraded protein samples
Solution: Add fresh protease inhibitors, maintain samples on ice, avoid freeze-thaw cycles
Problem: Incomplete protein extraction
Solution: Optimize lysis buffer composition, extend lysis time, ensure thorough homogenization
Antibody-Related Factors:
Detection Challenges:
Problem: Weak signal
Solution: Increase protein loading, extend exposure time, try enhanced chemiluminescence reagents
Problem: Multiple bands or non-specific binding
Solution: Increase blocking time, optimize washing steps, try different blocking agents
Molecular Weight Discrepancies:
Technical Considerations:
Problem: Uneven transfer
Solution: Ensure proper assembly of transfer sandwich, check buffer composition, optimize transfer conditions
Problem: Inconsistent loading
Solution: Validate with housekeeping protein controls, consider using total protein normalization methods
Validation Approaches:
Problem: Uncertainty about antibody specificity
Solution: Include positive controls (mouse spleen tissue, A431 cells, RAW 264.7 cells) , run samples from PSME1 knockdown cells
Problem: Batch-to-batch variability
Solution: Record lot numbers, maintain consistent antibody source, perform validation with each new lot
Following these troubleshooting strategies can help researchers achieve consistent and reliable results when using PSME1 antibodies in Western blot applications.
Ensuring reproducibility in studies examining PSME1's role in viral infections requires rigorous experimental design and methodological considerations:
Standardized Cell Culture and Viral Infection Models:
Maintain consistent passage numbers for cell lines (e.g., HepG2-NTCP for HBV studies)
Document and standardize viral stock preparation methods and titers
Implement quality control for viral preparations (sequence verification, infectious titer determination)
Control environmental variables (CO₂ levels, humidity, temperature)
Genetic Manipulation Controls:
Comprehensive Endpoint Measurements:
Proper Controls and Normalization:
Detailed Methodology Reporting:
Provide comprehensive details on experimental procedures
Report specific reagents, including antibody catalog numbers and dilutions
Document software and statistical methods used for analysis
Consider using reporting guidelines (e.g., ARRIVE for animal studies)
Cross-Validation Strategies:
Verify key findings in multiple cell lines or primary cells
Collaborate with independent laboratories for replication studies
Validate in vivo using appropriate animal models
Consider complementary approaches (e.g., CRISPR-Cas9 in addition to RNAi)
Data Sharing and Transparency:
Make raw data available through repositories
Share detailed protocols through platforms like protocols.io
Preregister study designs when possible
Report both positive and negative results
By implementing these measures, researchers can enhance the reproducibility and reliability of studies investigating PSME1's role in viral infections, particularly HBV, where PSME1 has been shown to affect viral replication through interaction with the core protein .
Research on PSME1 offers valuable insights into immune evasion mechanisms in persistent viral infections, potentially opening new avenues for therapeutic intervention:
Proteasome Regulation and Antigen Presentation:
Viral Protein Stabilization:
Interferon Response Modulation:
Cross-Viral Implications:
Clinical Correlations:
Future Research Directions:
Investigate how viruses might directly or indirectly modulate PSME1 expression
Explore whether PSME1 affects innate immune sensing of viral components
Determine if PSME1-mediated effects differ between acute and persistent infections
Examine potential interactions between PSME1 and viral immune evasion proteins
Understanding these mechanisms could lead to novel therapeutic strategies that target PSME1-mediated immune evasion, potentially breaking the cycle of viral persistence in chronic infections.
Current research on PSME1's role in cancer progression suggests several promising avenues for developing targeted therapies:
Targeting PSME1 in High-Expression Cancers:
Modulating Antigen Presentation for Immunotherapy:
PSME1 is involved in generating tumor antigens presented by MHC class I molecules
Manipulating PSME1 activity could potentially enhance tumor antigen presentation
This approach might increase tumor visibility to the immune system
Combination with immune checkpoint inhibitors could yield synergistic effects
Exploiting Proteasome-Dependent Cancer Vulnerabilities:
Cancer cells often show altered proteasome dependency
PSME1-targeted approaches could disrupt protein homeostasis selectively in cancer cells
This might be particularly effective in cancers with high protein synthesis rates
Biomarker-Guided Therapeutic Strategies:
Use PSME1 expression as a stratification biomarker for patient selection
Develop companion diagnostics to identify patients most likely to benefit
Monitor PSME1 levels as a marker of treatment response
Drug Delivery Innovations:
Develop antibody-drug conjugates targeting PSME1
Explore nanoparticle-based delivery of PSME1 inhibitors
Design proteasome-targeted prodrugs activated by PSME1-associated activities
Combination Therapy Approaches:
Combine PSME1-targeting agents with:
Conventional chemotherapy
Radiation therapy
Proteasome inhibitors
Immunotherapy
RNA Interference and Gene Editing Technologies:
As research progresses, preclinical studies should focus on validating these approaches in relevant cancer models, assessing potential toxicities, and determining optimal therapeutic windows before advancing to clinical development.
Gene expression profiling of PSME1 across different disease states offers valuable insights for developing personalized medicine approaches:
Disease-Specific Expression Patterns:
PSME1 shows differential expression across various pathological conditions:
These patterns can inform disease classification and stratification
Prognostic Applications:
Predictive Biomarker Development:
PSME1 expression levels might predict response to:
Antiviral therapies for HBV and other viral infections
Immunotherapies in cancer
Proteasome-targeting drugs
This could guide treatment selection and sequencing
Methodological Considerations:
Implementation Strategies:
Develop clinically validated assays for PSME1 expression measurement
Establish reference ranges and clinically relevant thresholds
Integrate PSME1 profiling with other molecular markers
Create decision support algorithms incorporating PSME1 status
Therapeutic Implications:
High PSME1 expressors might benefit from:
PSME1-targeting therapies
Proteasome inhibitors
Immune-modulating approaches
Low expressors might require alternative strategies
Longitudinal Monitoring:
Track PSME1 expression changes during disease progression
Monitor therapy-induced alterations in expression
Assess correlation with clinical outcomes
By integrating PSME1 expression data with other molecular and clinical parameters, personalized medicine approaches can be developed to optimize treatment selection, predict outcomes, and monitor therapeutic responses across viral infections, inflammatory conditions, and cancers where PSME1 plays a significant role.
Proteasome Activator Subunit 1 (PSME1), also known as PA28α, is a crucial component of the proteasome complex, which plays a significant role in protein degradation within cells. This article delves into the background of PSME1, its functions, and the relevance of mouse anti-human antibodies targeting this subunit.
The proteasome is a multicatalytic proteinase complex responsible for degrading unneeded or damaged proteins by proteolysis, a chemical reaction that breaks peptide bonds. The 26S proteasome consists of a 20S core and a 19S regulator. The 20S core is composed of four rings of 28 non-identical subunits, while the 19S regulator is composed of a base and a lid .
PSME1 encodes the alpha subunit of the 11S regulator, also known as PA28α. This subunit is part of the immunoproteasome, a modified proteasome involved in processing class I MHC peptides. The immunoproteasome contains an alternate regulator, the 11S regulator or PA28, which replaces the 19S regulator. The 11S regulator is composed of three alpha and three beta subunits forming a heterohexameric ring .
Research has shown that the expression of PSME1 is elevated in primary and metastatic human prostate cancer. This makes PSME1 a potential target for cancer therapy. Studies have demonstrated that antibodies against PSME1 can selectively localize to tumor sites, highlighting its potential as a therapeutic target .