ube2t Antibody

What is UBE2T and what cellular functions does it perform?

UBE2T (Ubiquitin-conjugating enzyme E2T) is a 23 kDa protein that functions as an E2 ubiquitin-conjugating enzyme in the ubiquitin-proteasome pathway. UBE2T catalyzes the covalent attachment of ubiquitin to protein substrates, accepting ubiquitin from the E1 complex and facilitating its transfer .

Functionally, UBE2T:

• Catalyzes monoubiquitination of substrate proteins

• Plays a critical role in the Fanconi anemia (FA) DNA repair pathway

• Specifically monoubiquitinates FANCD2, a key step in DNA damage response

• Is involved in mitomycin-C (MMC)-induced DNA repair processes

• Functions in cell cycle regulation and DNA replication

Defects in the UBE2T gene have been associated with Fanconi anemia of complementation group T (FANCT) .

For optimal performance of UBE2T antibodies, follow these storage and handling guidelines:

• Store at -20°C for long-term stability

• Antibodies are typically stable for one year after shipment when properly stored

• For -20°C storage, aliquoting is generally unnecessary

• Most formulations contain PBS with 0.02% sodium azide and 50% glycerol at pH 7.3

• Some preparations (20μl sizes) may contain 0.1% BSA

• Always follow manufacturer-specific guidelines for your particular antibody

• Avoid repeated freeze-thaw cycles to maintain antibody integrity

How is UBE2T involved in cancer development and progression?

UBE2T has been implicated in multiple cancer types with consistent findings regarding its role in oncogenesis:

• Bladder Cancer: UBE2T is significantly upregulated in bladder cancer tissues and cell lines. Knockdown of UBE2T suppresses bladder cancer cell proliferation and colony formation while inducing cell cycle arrest at G2/M phase and increasing apoptosis .

• Breast Cancer: UBE2T is overexpressed in patient-derived breast cancer samples, and its overexpression predicts poor prognosis. The transcription factor AP-2 alpha (TFAP2A) drives UBE2T overexpression in breast cancer cells. UBE2T inhibition suppresses breast cancer tumor growth by regulating IFI6 (interferon alpha-inducible protein 6), promoting DNA replication stress, cell cycle arrest, and apoptosis .

• Lung Adenocarcinoma: UBE2T promotes stage I lung adenocarcinoma progression, affecting cellular proliferation, migration, and invasion .

• Hepatocellular Carcinoma: UBE2T promotes HCC development by increasing Akt K63-mediated ubiquitination and Akt/β-catenin signaling pathway activation, leading to upregulation of pyrimidine metabolism enzymes .

• Multiple Myeloma: UBE2T is frequently amplified and/or overexpressed in multiple myeloma, where it is required for homologous recombination activity. Increased copy number or expression of UBE2T is associated with poor patient survival .

• Retinoblastoma: UBE2T promotes retinoblastoma proliferation via the STAT3 signaling pathway .

What are the experimental approaches for studying UBE2T function?

Several validated experimental approaches can be used to study UBE2T function:

UBE2T Knockdown Studies:

• siRNA-mediated knockdown: Validated siRNA sequences include:

  • siUBE2T-1: GCAACTGTGTTGACCTCTA

  • siUBE2T-2: CCAGTCAGCTAGTAGGCAT

  • siUBE2T-3: CCTGGTTCATCTTAGTTAA

• Lentivirus-mediated shRNA delivery for stable knockdown

Functional Assays Post-Knockdown:

• Cell proliferation assays (CCK-8, colony formation)

• Cell cycle analysis using flow cytometry

• Apoptosis assessment

• Migration and invasion assays (Transwell)

UBE2T-Specific Rescue Experiments:

• Complementation assays using wild-type UBE2T expression in deficient cells

• Testing of cellular sensitivity to crosslinking agents (MMC, DEB, cisplatin)

• Analysis of cell cycle distribution following treatment

• Assessment of FANCD2/FANCI monoubiquitination rescue

Mutagenesis Studies:

• Site-directed mutagenesis of key UBE2T residues:

  • Catalytic cysteine (C86A) - enzyme-deficient mutation

  • Loop mutations (D32A, D33A, L92A or DDL/AAA)

  • Loop7 deletion (Δ92-95)

Protein-Protein Interaction Studies:

• Co-immunoprecipitation to identify UBE2T binding partners

• Analysis of UBE2T's interaction with E3 ligases and substrates

How can I validate UBE2T antibody specificity?

To ensure reliable UBE2T antibody specificity, implement these validation approaches:

Positive and Negative Controls:

• Positive Controls: Use cell lines with confirmed UBE2T expression such as HeLa, HepG2, K-562, Jurkat, and SKOV-3 cells for Western blot

• Negative Controls: Use UBE2T knockdown or knockout samples as negative controls

Multiple Detection Methods:

• Compare results across different applications (WB, IP, IF/ICC)

• Use at least two different UBE2T antibodies targeting different epitopes

• Verify observed molecular weight (23 kDa is the expected size)

Knockdown Validation:

• Perform siRNA or shRNA-mediated knockdown of UBE2T

• Verify reduction in signal by Western blot and other detection methods

Rescue Experiments:

• Reintroduce UBE2T expression in knockdown cells

• Confirm restoration of antibody signal

Application-Specific Validation:

• For IHC: Compare staining patterns in normal vs. tumor tissues

• For IF: Verify expected nuclear and cytoplasmic localization, with stronger nuclear staining

What is the role of UBE2T in the Fanconi anemia DNA repair pathway?

UBE2T serves as a critical E2 ubiquitin-conjugating enzyme in the Fanconi anemia (FA) pathway, with specific functions:

• FANCD2/FANCI Monoubiquitination: UBE2T specifically catalyzes the monoubiquitination of FANCD2 and FANCI, which is essential for the activation of the FA DNA repair pathway in response to DNA damage, particularly interstrand crosslinks .

• E3 Ligase Interaction: UBE2T interacts with the FANCL RING domain (the E3 ligase component of the FA core complex), which stimulates UBE2T's ubiquitin transfer activity. This interaction is crucial for proper FA pathway function .

• Autoregulation Mechanism: Interaction between UBE2T and FANCL can stimulate UBE2T auto-monoubiquitination, primarily at Lys91 near the active site. This automodification leads to UBE2T inactivation, providing a negative regulatory mechanism for the FA pathway .

• Clinical Significance: Deficiency of UBE2T results in Fanconi anemia-T subtype, characterized by cellular hypersensitivity to DNA crosslinking agents and genomic instability. Complementation with wild-type UBE2T rescues this phenotype .

• Structural Insights: X-ray crystallography and mutagenesis studies have identified key functional regions in UBE2T:

  • The catalytic cysteine (Cys86) serves as the active site

  • Regions near α1 and α2 form critical protein-protein interaction interfaces

  • Specific pockets identified by 19F-NMR fragment screening represent potential targeting sites for inhibitors

How do post-translational modifications affect UBE2T function?

UBE2T undergoes several post-translational modifications that regulate its activity and function:

Auto-monoubiquitination:

• UBE2T catalyzes its own monoubiquitination, primarily at Lys91 near the active site

• This self-modification serves as a negative regulatory mechanism

• FANCL interaction stimulates this auto-ubiquitination process

• Auto-ubiquitination leads to UBE2T inactivation and downregulation of the FA pathway

Site-specific Ubiquitination:

• Besides Lys91, UBE2T can auto-ubiquitinate several lysines in its C-terminal extension

• Studies using C-terminal truncation (UBE2T1-152) have helped isolate the contribution of specific ubiquitination sites

• Lys91Arg mutation (K91R) abolishes auto-modification activity

Functional Consequences:

• Auto-ubiquitinated UBE2T shows reduced catalytic activity

• These modifications regulate the cellular availability of active UBE2T

• Balanced regulation of UBE2T activity is crucial for proper DNA repair function

Experimental Approaches:

• Site-directed mutagenesis (K91R) to prevent auto-ubiquitination

• C-terminal truncations to eliminate additional ubiquitination sites

• In vitro auto-ubiquitination assays to assess E2 activity

• Immunoblotting with anti-ubiquitin antibodies to detect modified forms

What are emerging approaches for targeting UBE2T in cancer therapy?

Recent research has identified several promising approaches for targeting UBE2T in cancer therapy:

Small Molecule Inhibitors:

• Fragment-based screening has identified compounds binding to UBE2T

• X-ray crystallography has revealed two key binding pockets:

  • One near Cys86 (the active site) that could interfere with ubiquitin transport

  • A second pocket near the UBE2T-FANCL RING interaction interface

• Pyrimidinone core compounds and their structural analogs have been developed

• Compound 7 (IC50 = 288.2 μM) showed approximately 10-fold increase in binding affinity compared to initial hits

Combination Therapies:

• UBE2T inhibition enhances sensitivity to DNA replication stress inducers

• Combination with drugs like hydroxyurea and aphidicolin shows increased efficacy

• Leflunomide, a clinically approved DHODH inhibitor, blocks UBE2T-promoted cancer progression in HCC models

Pathway-Based Approaches:

• Targeting downstream effectors in UBE2T-mediated pathways:

  • In breast cancer: UBE2T→IFI6→DNA replication stress→apoptosis pathway

  • In HCC: UBE2T→Akt K63-ubiquitination→β-catenin activation→pyrimidine metabolism

  • In retinoblastoma: UBE2T/STAT3 signaling pathway

Biomarker Development:

• UBE2T overexpression correlates with poor prognosis in multiple cancers

• Immunohistochemical evaluation using standardized scoring systems:

  • Immunoreactive score (IRS) calculation based on staining intensity and extent

  • Scores categorizing UBE2T expression as high (IRS ≥4) or low (IRS ≤3)

Rational Drug Design Considerations:

• Structure-based design targeting specific UBE2T pockets

• PPI (protein-protein interaction) libraries as resources for novel inhibitors

• Further optimization of current fragment hits to improve potency and specificity

What methodological challenges exist in studying UBE2T protein interactions?

Researchers face several methodological challenges when investigating UBE2T protein interactions:

Capturing Transient E2-E3 Interactions:

• UBE2T interactions with E3 ligases (like FANCL) are often transient and dynamic

• Critical residues in allosteric networks, including Arg3, Asp32/Asp33, and Leu92, affect these interactions

• Mutations in loop regions (loop7 deletion Δ92-95) or hybrid mutations (D32A, D33A, L92A) significantly impact interaction efficiency

• Advanced approaches like crosslinking or rapid kinetics methods may be required

Distinguishing Direct vs. Indirect Effects:

• UBE2T impacts multiple cellular pathways

• Challenge in determining whether effects are due to direct UBE2T interactions or indirect consequences

• For example, UBE2T regulates IFI6 mRNA expression in breast cancer, but the mechanism (direct or via intermediary factors) remains unclear

Analyzing Ubiquitin Chain Types:

• UBE2T promotes K63-linked ubiquitination of Akt in HCC

• Different ubiquitin chain types (K48 vs. K63) have distinct functional outcomes

• Requires specialized techniques like linkage-specific antibodies or mass spectrometry

• Ubiquitination-site-deficient mutants (e.g., Akt K8/14R) are needed to confirm specificity

Studying Domain-Specific Functions:

• UBE2T contains multiple functional domains with distinct roles

• Catalytic cysteine (C86A) mutations can separate enzymatic from non-enzymatic functions

• Loop regions mediate specific protein-protein interactions

• Structural studies using X-ray crystallography and NMR are needed for complete understanding

Technical Considerations for Detection Methods:

• Co-immunoprecipitation protocols must be optimized for UBE2T's size (23 kDa)

• Antibody selection is critical, with verification of specificity across applications

• Post-translational modifications can alter detection efficiency

• Subcellular localization (nuclear and cytoplasmic) requires appropriate fractionation techniques

How can I optimize UBE2T antibody-based detection in different experimental systems?

For optimal UBE2T detection across various experimental platforms, consider these application-specific optimizations:

Western Blot Optimization:

• Recommended dilution range: 1:500-1:2000

• Sample preparation: Best detected in total cell lysates from HeLa, HepG2, K-562, Jurkat, or SKOV-3 cells

• Expected molecular weight: 23 kDa

• Buffer system: Standard SDS-PAGE with PVDF or nitrocellulose membranes

• Blocking: 5% non-fat milk or BSA in TBST

• Secondary antibody: Anti-rabbit IgG for most UBE2T antibodies

Immunoprecipitation Optimization:

• Recommended antibody amount: 0.5-4.0 μg for 1.0-3.0 mg of total protein lysate

• Cell system: Successfully validated in HeLa cells

• Pre-clearing lysate helps reduce background

• Protein A/G beads work well with rabbit polyclonal and monoclonal antibodies

Immunofluorescence/ICC Optimization:

• Recommended dilution: 1:200-1:800

• Fixation: 4% paraformaldehyde followed by permeabilization

• Expected localization: Both nuclear and cytoplasmic, with stronger nuclear signal

• Successfully validated in HepG2 cells

• Include nuclear counterstain (DAPI) to confirm nuclear localization

Immunohistochemistry Optimization:

• Semi-quantitative immunoreactive score (IRS) system recommended for evaluation

• Scoring based on staining intensity (0-3) and extent (0-4)

• IRS ≤3 considered low expression, IRS ≥4 considered high expression

• Primary antibody concentration requires tissue-specific optimization

• Antigen retrieval methods may need optimization based on tissue type and fixation

What are the best experimental controls for UBE2T functional studies?

Implement these critical controls in UBE2T functional studies for reliable results:

Expression Controls:

• Positive Controls: Cell lines with verified UBE2T expression (HeLa, HepG2, K-562)

• Tissue Controls: Compare normal vs. tumor tissues with documented UBE2T expression differences

• Negative Controls: UBE2T knockout or knockdown samples

• Loading Controls: GAPDH, β-actin, or other housekeeping proteins for normalization

Functional Assay Controls:

• Rescue Controls: Re-expression of wild-type UBE2T in knockdown cells

• Catalytic Mutant Controls: UBE2T-C86A (catalytically inactive) to distinguish enzymatic from scaffolding functions

• Domain Mutants: Mutations in specific domains (e.g., loop regions) to assess domain-specific functions

• Treatment Controls: Appropriate vehicle controls for drug treatments

Knockdown/Knockout Validation:

• Multiple siRNA Sequences: Test at least 2-3 different siRNA sequences to rule out off-target effects

• Quantitative Assessment: RT-qPCR to verify mRNA reduction and Western blot for protein reduction

• Functional Verification: Assess expected phenotypes (e.g., DNA damage sensitivity)

Ubiquitination Assay Controls:

• Substrate Mutants: Use ubiquitination-site mutants (e.g., K→R mutations) as negative controls

• E2 Activity Controls: Include UBE2T auto-ubiquitination assays as positive controls for E2 activity

• Chain-Specificity Controls: Include ubiquitin mutants (K48R, K63R) to verify linkage specificity

• E3 Dependency: Include assays with and without E3 ligase to determine E3 dependency

DNA Repair Function Controls:

• Crosslinking Agent Controls: Include dose-response curves for MMC, DEB, or cisplatin

• Cell Cycle Analysis: Confirm G2/M arrest following DNA damage in UBE2T-deficient cells

• FANCD2 Monoubiquitination: Verify impaired FANCD2/FANCI monoubiquitination

• Foci Formation: Assess nuclear foci formation of DNA repair proteins

How can conflicting UBE2T research findings be reconciled?

When confronted with conflicting research findings regarding UBE2T, consider these methodological approaches to reconciliation:

Context-Dependent Functions:

• UBE2T functions differently across cancer types and cellular contexts

• In breast cancer, UBE2T works through the IFI6 pathway

• In HCC, it operates via Akt K63-ubiquitination and β-catenin activation

• In retinoblastoma, it functions through STAT3 signaling

• Specific pathway analysis in each cellular context is necessary for reconciliation

Methodological Variations:

• Different antibodies targeting distinct epitopes may yield varying results

• Knockdown efficiency variations can lead to different phenotypic outcomes

• Cell line-specific differences in UBE2T dependency exist

• Standardize methodologies when comparing across studies, including:

  • Antibody validation procedures

  • Knockdown protocols and efficiency verification

  • Functional assay conditions

Integrative Analysis Approaches:

• Combine multiple techniques to verify findings:

  • Pair genetic approaches (siRNA, CRISPR) with pharmacological inhibition

  • Validate in vitro findings with in vivo models

  • Use multiple cell lines to establish generalizability

  • Apply both gain- and loss-of-function approaches

Advanced Molecular Analysis:

• For contradictory findings on UBE2T's role in specific pathways:

  • Use proximity ligation assays to verify protein-protein interactions

  • Apply CRISPR-based genetic screens to identify context-dependent synthetic lethal interactions

  • Employ proteomics to comprehensively map UBE2T interaction networks

  • Use structural biology approaches to validate binding interfaces

Addressing Technical Limitations:

• Acknowledge inherent limitations in current research:

  • UBE2T might affect cell growth through alternative mechanisms beyond identified pathways

  • Effects on IFI6 could be through UBE2T-independent mechanisms

  • UBE2T might affect ubiquitination of multiple proteins beyond identified targets

  • Further comprehensive studies are required to fully map UBE2T functions