UXT Antibody

What is UXT and what are its primary cellular functions?

UXT (Ubiquitously Expressed Transcript) is a prefoldin-like protein involved in multiple cellular processes. Its primary functions include:

• Acting as a chaperone that prevents proteotoxicity by serving as an autophagy adaptor for p62-dependent aggrephagy

• Regulating gene transcription through interaction with androgen receptor (AR) and estrogen receptor (ESR1)

• Functioning as a nuclear chaperone that facilitates NF-kappa-B enhanceosome formation

• Serving as an essential component of centrosomes, where it associates with γ-tubulin and influences centrosome structure

• Suppressing cell transformation through interaction with cell proliferation and survival stimulatory factors

• Protecting cells against TNF-alpha-induced apoptosis

The diversity of UXT functions makes it a significant target for research across multiple areas of cell biology and cancer research.

What types of UXT antibodies are available for research applications?

Several types of UXT antibodies have been developed for research applications. These include:

• Monoclonal antibodies: Examples include the 1B2, 15A6, and 6D3 clones described in the literature, which have different properties for Western blot and immunostaining applications

• Polyclonal antibodies: Mouse polyclonal UXT antibodies suitable for Western blot (WB) and immunocytochemistry/immunofluorescence (ICC/IF) applications with human samples

Different antibodies may recognize specific conformations or epitopes of UXT. For instance, some antibodies like 15A6 and 6D3 bind to the native conformation of UXT but not the denatured protein, while others like 1B2 can recognize both native and denatured forms in Western blots .

What experimental applications are UXT antibodies suitable for?

UXT antibodies have been validated for several experimental applications:

• Western blot (WB): For detecting UXT protein expression levels in cell and tissue lysates

• Immunocytochemistry/Immunofluorescence (ICC/IF): For visualizing subcellular localization of UXT, particularly its centrosomal localization

• Immunoprecipitation (IP): For studying protein-protein interactions involving UXT

• Cellular imaging: For monitoring UXT dynamics during different cell cycle stages and in response to various treatments

When selecting a UXT antibody, researchers should consider the specific application and whether recognition of native or denatured protein is required. For instance, antibody 1B2 works well for Western blot but is not suitable for immunostaining of fixed cells, while antibodies 15A6 and 6D3 work for immunostaining but not for Western blot .

How does the oligomeric structure of UXT relate to its function in autophagy?

The oligomeric structure of UXT is crucial for its function in autophagy and protection against proteotoxicity. Recent structural analysis using AlphaFold has revealed that:

• UXT forms a homomeric hexamer with a β-barrel structure in the middle, created by two β hairpins from each UXT subunit

• Each UXT subunit contributes two α helices, forming a 12 tentacle-like structure that can bind to misfolded proteins through hydrophobic surfaces

• Additional β hairpins outside the hexameric structure, particularly the FFXD/E motif, enable inter-hexameric interactions leading to high-order UXT oligomers

• These high-order oligomers present misfolded protein-binding sites in various directions, allowing effective binding and aggregation of misfolded proteins

This distinctive structural feature differentiates UXT from prefoldin (which lacks additional β hairpins) and explains UXT's efficiency in forming protein aggregates and delivering them to the autophagy machinery rather than the refolding pathway .

To study UXT oligomerization experimentally, researchers can use techniques such as:

• Size exclusion chromatography to separate different oligomeric forms

• Cross-linking assays followed by Western blot to capture oligomeric states

• Fluorescence recovery after photobleaching (FRAP) to analyze the dynamics of UXT-associated protein aggregates

What is the relationship between UXT, protein aggregates, and the p62-dependent autophagy pathway?

UXT plays a critical role in targeting protein aggregates for degradation through the p62-dependent autophagy pathway. The mechanism involves:

• UXT binding directly to misfolded proteins through its hydrophobic surfaces

• Formation of UXT hexamers that stabilize around misfolded proteins

• Assembly of high-order UXT oligomers that facilitate the aggregation of misfolded proteins within a limited space

• Exposure of multiple p62-binding sites on the UXT molecules within the complex

• Enhanced recruitment of the autophagy receptor p62 to the aggregates, increasing avidity

• Efficient delivery of the aggregates to phagophores for autophagic removal

Experimental evidence shows that UXT can recruit p62 to protein aggregates even when p62's ubiquitin-binding capacity is impaired (using the p62(F406V) mutant), indicating that UXT provides an alternative mechanism for targeting aggregates to the autophagy machinery .

This relationship is particularly significant because it suggests UXT evolved from a chaperone-like function to become integrated into the autophagy system specifically for handling misfolded proteins that cannot be refolded .

How does UXT expression correlate with tumorigenesis and cancer progression?

UXT has been implicated in tumorigenesis through several mechanisms:

• UXT is overexpressed in multiple human tumor tissues but not in matching normal tissues, suggesting a potential role in cancer development

• As a centrosomal protein associated with γ-tubulin, UXT overexpression disrupts centrosome structure, which could contribute to genomic instability—a hallmark of cancer

• UXT may facilitate transformation by corrupting regulated centrosome functions

• Increasing concentrations of UXT can contribute to progressive aggregation of mitochondria and cell death through its association with LRPPRC

• UXT suppresses cell transformation, potentially by interacting with and inhibiting the biological activity of cell proliferation and survival stimulatory factors like MECOM

The dual nature of UXT—both as a potential oncogene when overexpressed and as a tumor suppressor in some contexts—suggests its role in cancer may be context-dependent and requires careful experimental design to elucidate in specific cancer types.

What are the optimal conditions for using UXT antibodies in immunofluorescence studies?

For optimal immunofluorescence detection of UXT, consider the following methodology:

• Fixation method: Paraformaldehyde (4%) fixation for 15-20 minutes at room temperature preserves UXT structure while maintaining cellular architecture

• Permeabilization: Use 0.2% Triton X-100 for 5-10 minutes to allow antibody access to intracellular UXT without disrupting its native conformation

• Blocking conditions: 3-5% BSA or normal serum (matching secondary antibody host) for 30-60 minutes reduces non-specific binding

• Antibody selection: Choose antibodies specifically validated for immunofluorescence. For example:

  • Monoclonal antibodies 15A6 and 6D3 are suitable for immunostaining of native UXT

  • Antibody 1B2 is not recommended for immunostaining as it does not effectively bind UXT in fixed cells

• Antibody controls:

  • Always include a negative control (secondary antibody only)

  • Pre-adsorption control: Incubate antibody with purified UXT protein before staining to confirm specificity

  • Consider using UXT-depleted cells as additional negative controls

• Co-staining recommendations:

  • For centrosomal localization, co-stain with γ-tubulin as a centrosome marker

  • For mitotic spindle association, co-stain with α-tubulin

  • For protein aggregate studies, co-stain with p62 or ubiquitin

• Image acquisition: Use confocal microscopy with appropriate wavelengths for fluorophores to achieve optimal resolution of centrosomal and aggregate structures

How can researchers effectively study UXT-dependent protein aggregation in cellular models?

To study UXT-dependent protein aggregation effectively, researchers can implement the following methodological approach:

• Cellular models selection:

  • HEK293T cells are well-documented for UXT aggregate studies

  • HeLa/p62KO cells can be used to study UXT function independent of p62

  • Motor neuron models for neurodegenerative disease contexts

• Experimental system setup:

  • Co-expression of GFP-tagged UXT with aggregation-prone proteins (e.g., SOD1(A4V))

  • Treatment with proteasome inhibitors (e.g., MG132) to enhance protein aggregation

  • Autophagy inhibitors (e.g., Bafilomycin A1) to study aggregate clearance mechanisms

• Aggregate detection and quantification:

  • Fluorescence microscopy for live-cell imaging of aggregate formation and dynamics

  • FRAP (Fluorescence Recovery After Photobleaching) to measure aggregate stability:

    • Bleach half of the aggregate with a 488-nm laser

    • Measure fluorescence recovery at 2-second intervals for 10 minutes

    • Calculate mobility parameters as shown in published protocols

• Biochemical fractionation:

  • Separate detergent-soluble and detergent-insoluble fractions to quantify aggregation:

    • Soluble fraction: Extract with RIPA buffer

    • Insoluble fraction: Extract remaining pellet with SDS buffer

    • Analyze both fractions by Western blot

• UXT oligomerization assessment:

  • Use UXT mutants that affect oligomerization (e.g., UXT(C'A4))

  • Compare with UXT oligomerization-competent controls (e.g., UXT(C'A4)-hub)

  • Analyze effects on aggregate formation and clearance

What approaches can be used to investigate UXT's role in centrosome structure and function?

To investigate UXT's role in centrosome structure and function, researchers can employ these methodological approaches:

• Centrosome visualization:

  • Immunofluorescence microscopy with co-staining of UXT and centrosomal markers:

    • γ-tubulin for centrosome core

    • α-tubulin for spindle poles during mitosis

    • Pericentrin for pericentriolar material

• UXT manipulation strategies:

  • Overexpression: EGFP-tagged or FLAG-tagged UXT constructs

  • Knockdown: siRNA targeting UXT (with careful titration as complete knockdown causes cell death)

  • Knockout: Inducible systems to study early effects before cell death

• Functional assays:

  • Centrosome duplication assay: Monitor centrosome number per cell after UXT manipulation

  • Microtubule regrowth assay: Depolymerize microtubules with cold treatment and measure regrowth rates

  • Mitotic spindle assembly: Assess spindle formation and chromosome alignment during mitosis

  • Cell cycle progression: Flow cytometry to determine effects on cell cycle phases

• Protein interaction studies:

  • Co-immunoprecipitation with centrosomal proteins (e.g., Cdc14A)

  • Proximity ligation assay to confirm protein interactions in situ

  • Mass spectrometry of UXT immunoprecipitates to identify novel centrosomal partners

• Live-cell imaging:

  • Time-lapse microscopy of stable cell lines expressing EGFP:UXT

  • Monitor centrosome dynamics throughout the cell cycle

  • Quantify parameters like centrosome movement, splitting, and maturation

What are common challenges when using UXT antibodies in Western blot and how can they be overcome?

Researchers may encounter several challenges when using UXT antibodies in Western blot applications:

• Challenge: Low or no signal detection
  Solutions:

  • Ensure using the correct antibody for Western blot (e.g., 1B2 works for Western blot while 15A6 and 6D3 do not)

  • Optimize protein extraction method (RIPA buffer with protease inhibitors works well for UXT)

  • Increase antibody concentration or extend incubation time

  • Add denaturation enhancers (8M urea or heating at 95°C for 10 minutes) to improve epitope exposure

  • Use enhanced chemiluminescence (ECL) detection with longer exposure times

• Challenge: Multiple bands or unexpected molecular weight
  Solutions:

  • Verify expected molecular weight (approximately 18 kDa for endogenous UXT)

  • For tagged versions, account for tag size (FLAG-UXT: ~20 kDa, EGFP-UXT: ~45 kDa)

  • Include appropriate positive controls (recombinant UXT protein)

  • Run UXT-depleted samples as negative controls

  • Use gradient gels (4-15%) to better resolve UXT bands

  • For oligomeric forms, try non-reducing conditions to preserve disulfide bonds

• Challenge: High background
  Solutions:

  • Increase blocking time or concentration (5% non-fat milk or BSA)

  • Add 0.1-0.3% Tween-20 to washing buffer

  • Optimize secondary antibody dilution (typically 1:5000-1:10000)

  • Consider using alternative membrane types (PVDF may give cleaner results than nitrocellulose)

  • Pre-adsorb primary antibody with cell lysate from UXT-depleted cells

• Challenge: Variable UXT detection across samples
  Solutions:

  • Note that UXT has a short half-life and undergoes rapid degradation via the ubiquitin-proteasome system

  • Treat samples with proteasome inhibitors (e.g., MG132) to stabilize UXT levels

  • Standardize sample collection and protein extraction procedures

  • Normalize loading with appropriate housekeeping proteins

How can researchers distinguish between different oligomeric states of UXT in experimental systems?

Distinguishing between different oligomeric states of UXT presents technical challenges that can be addressed through these methodological approaches:

• Biochemical separation techniques:

  • Native PAGE: Run samples on non-denaturing gels to preserve oligomeric structures

  • Size exclusion chromatography: Separate different-sized oligomers based on elution volume

  • Sucrose gradient ultracentrifugation: Fractionate samples based on sedimentation coefficient

  • Blue native PAGE: Particularly useful for membrane protein complexes

• Cross-linking approaches:

  • Chemical cross-linking with DSS or formaldehyde followed by SDS-PAGE

  • Cross-linking mass spectrometry (XL-MS) to identify inter-subunit contact points

  • In-cell cross-linking to capture physiological oligomeric states

  • Titrate cross-linker concentration to capture intermediate oligomeric forms

• Mutational analysis:

  • Generate UXT mutants that disrupt specific oligomerization interfaces:

    • UXT(C'A4): Disrupts high-order oligomerization while maintaining hexamer formation

    • UXT(C'A4)-hub: Restores high-order oligomerization potential through alternative means

  • Compare functional outcomes of different mutants in cellular assays

• Imaging techniques:

  • Fluorescence fluctuation spectroscopy to determine oligomer size distribution

  • Förster resonance energy transfer (FRET) between differently labeled UXT molecules

  • Single-molecule imaging to directly visualize oligomeric species

  • Super-resolution microscopy (STORM/PALM) to visualize UXT clusters in cells

• Functional correlation:

  • Compare aggregate binding capacity across different oligomeric states

  • Measure protective effects against proteotoxicity using cell viability assays

  • Assess autophagy efficiency with different UXT variants using LC3 turnover assays

  • Correlate oligomeric state with p62 recruitment efficiency

What controls should be included when studying UXT-dependent autophagy in experimental models?

When investigating UXT-dependent autophagy, researchers should include these essential controls:

• UXT expression controls:

  • Knockdown/knockout controls: siRNA or CRISPR/Cas9-mediated UXT depletion

  • Overexpression controls: Empty vector, untagged UXT, differently tagged UXT (FLAG, GFP)

  • Mutant controls: Non-oligomerizing UXT mutants (UXT(C'A4)) and restored oligomerization mutants (UXT(C'A4)-hub)

• Autophagy pathway controls:

  • Positive controls: Rapamycin or starvation to induce autophagy

  • Negative controls:

    • Pharmacological inhibitors: Bafilomycin A1 to block autophagosome-lysosome fusion

    • Genetic inhibition: ATG5 or ATG7 knockdown to impair autophagosome formation

  • p62 controls:

    • p62 knockout cells (HeLa/p62KO)

    • p62 mutants (p62(F406V)) with impaired ubiquitin binding

• Protein aggregation controls:

  • Aggregation-prone proteins: SOD1(A4V) , ataxin-1(92Q)

  • Proteasome inhibition: MG132 treatment to enhance aggregation

  • Solubility controls: Compare detergent-soluble and insoluble fractions

• Microscopy controls:

  • Antibody specificity: Pre-adsorption with purified UXT protein

  • Fluorescent protein artifacts: Compare untagged and tagged versions

  • Photobleaching controls: Unbleached regions of the same cell in FRAP experiments

• Experimental timing controls:

  • Time-course experiments: Capture the dynamic nature of UXT-mediated protein aggregation and clearance

  • Pulse-chase designs: To distinguish between effects on aggregate formation versus clearance

  • Cell cycle synchronization: As UXT localization may vary with cell cycle stage

What are emerging research areas for UXT antibodies in neurodegenerative disease studies?

The role of UXT in protein aggregation and autophagy suggests potential applications in neurodegenerative disease research:

• Protein aggregate clearance in neurodegeneration:

  • UXT's protective effect against SOD1(A4V) aggregates in motor neurons indicates potential relevance to amyotrophic lateral sclerosis (ALS)

  • The ability of UXT to form high-order oligomers that enhance autophagy suggests it may facilitate clearance of other disease-associated aggregates such as:

    • Tau in Alzheimer's disease

    • α-synuclein in Parkinson's disease

    • Huntingtin in Huntington's disease

• UXT as a therapeutic target:

  • Development of compounds that enhance UXT's oligomerization potential

  • Screening for molecules that stabilize UXT protein levels, which normally undergo rapid degradation

  • Engineering UXT variants with enhanced aggregate recognition specificity

• Biomarker development:

  • Investigating whether UXT levels or oligomerization status correlates with disease progression

  • Developing sensitive assays to detect UXT-aggregate complexes in patient samples

  • Exploring imaging approaches to monitor UXT activity in neural tissues

• Systems biology approaches:

  • Integration of UXT into protein quality control networks

  • Modeling UXT-dependent aggregate dynamics in different neuronal subtypes

  • Investigation of cell-type specific responses to UXT manipulation

Researchers entering this field should consider using advanced cellular models such as patient-derived iPSCs differentiated into relevant neuronal subtypes, organoids, or animal models expressing UXT variants to fully understand its potential in neurodegeneration research.

How can structural insights about UXT oligomerization inform antibody development and experimental design?

Recent structural insights into UXT oligomerization provide valuable information for antibody development and experimental design:

• Epitope-specific antibody development:

  • Design antibodies targeting specific structural domains:

    • β-barrel core epitopes for detecting UXT hexamers

    • FFXD/E motif region for studying high-order oligomerization

    • Tentacle-like α-helical regions involved in misfolded protein binding

  • Develop conformation-specific antibodies that distinguish between:

    • Monomeric UXT

    • Hexameric UXT

    • High-order UXT oligomers

• Structure-guided experimental approaches:

  • Design mutations that specifically disrupt either hexamer formation or inter-hexamer interactions

  • Create fluorescent sensors that report on UXT oligomerization state in live cells

  • Engineer chimeric proteins between UXT and prefoldin to investigate structural determinants of function

• Improved imaging strategies:

  • Develop proximity-based sensors (FRET, BiFC) positioned at key interfaces in the UXT structure

  • Design super-resolution microscopy approaches to visualize oligomeric structures below diffraction limit

  • Create probes that specifically bind to UXT-aggregate complexes

• Therapeutic development opportunities:

  • Design peptides that enhance or inhibit specific UXT oligomerization interfaces

  • Develop small molecules that stabilize beneficial UXT oligomeric states

  • Engineer modified UXT variants with enhanced activity for potential protein replacement therapies

• Quantitative assay development:

  • Establish in vitro assays to measure:

    • UXT oligomerization kinetics

    • Binding affinity to different misfolded proteins

    • p62 recruitment efficiency

  • Develop high-throughput screening platforms to identify modulators of UXT function

The AlphaFold-predicted structure of UXT provides a valuable framework for these approaches, although researchers should validate key structural features experimentally using techniques such as X-ray crystallography or cryo-EM.