TFEB Antibody

What is the molecular weight of TFEB protein when detected by Western blot?

TFEB typically appears at approximately 65-70 kDa on Western blots, though the exact size may vary slightly based on phosphorylation state and experimental conditions . Commercial antibodies consistently report this molecular weight range in their product specifications. When conducting Western blot analysis, it's advisable to use positive control lysates from cells known to express TFEB, such as Raji human Burkitt's lymphoma cell line . The apparent molecular weight can be affected by:

• Post-translational modifications (especially phosphorylation)

• Sample preparation conditions

• Gel percentage

• Running buffer composition

Which cellular compartments typically show TFEB immunoreactivity?

TFEB shows distinct immunoreactivity patterns depending on cellular conditions:

• Cytoplasmic punctae: Distributed throughout the cytoplasm in small (~0.3 μm) punctate structures

• Nuclear punctae: In actively transcribing cells, particularly following nutrient deprivation

• Nucleolar localization: Strong labeling in the nucleolar portion of the nuclear compartment in some neurons

• Perinuclear cytoplasmic clusters: Larger TFEB immunoreactive structures (>0.7 μm) often observed in disease states and stressed cells

Immunofluorescence studies in A549 human lung carcinoma cells demonstrate that under normal conditions, TFEB staining can be localized to the cytoplasm with specific antibodies such as MAB9170 .

How should I optimize TFEB detection by Western blotting?

For optimal TFEB detection by Western blot:

• Sample preparation:

  • Use reducing conditions (e.g., Immunoblot Buffer Group 1)

  • Include phosphatase inhibitors to preserve phosphorylation states

• Antibody selection and dilution:

  • For commercial antibodies: use recommended dilutions (typically 1:1000)

  • Primary incubation: 1-2 hours at room temperature or overnight at 4°C

• Detection system:

  • Use appropriate secondary antibodies (e.g., HRP-conjugated Anti-Mouse IgG)

  • Consider enhanced chemiluminescence for sensitive detection

• Controls:

  • Positive control: Raji human Burkitt's lymphoma cell line lysates

  • Negative control: Lysates from TFEB knockdown cells

What are the critical phosphorylation sites on TFEB that affect its localization and function?

TFEB function is regulated by phosphorylation at several key sites:

Phospho-specific antibodies have been developed for these sites, with distinct specificity profiles:

• p-S466 antibodies detect single p-S466 and dually phosphorylated p-S466/S467 peptides

• p-S467 antibodies specifically detect single p-S467 phospho-peptide

• p-S466/S467 antibodies recognize dually phosphorylated p-S466/S467 and single p-S467 peptide

These phospho-specific antibodies are valuable tools for studying the regulatory mechanisms controlling TFEB nuclear translocation and activity.

How can I reliably quantify TFEB nuclear translocation in response to cellular stressors?

Quantifying TFEB nuclear translocation requires careful experimental design:

• Immunofluorescence approach:

  • Fix cells using paraformaldehyde (typically 4%)

  • Counterstain nuclei with DAPI

  • Image using confocal microscopy

  • Analyze nuclear/cytoplasmic TFEB ratio

• Semi-quantitative scoring system:
  Based on established protocols, use a scoring system such as:

  • Score 1: Pronounced lower density of punctate TFEB in nucleus versus cytoplasm

  • Score 2: Comparable densities of punctate TFEB in nucleus versus cytoplasm

  • Score 3: Pronounced nucleolar labeling

• Quantitative analysis:

  • Use image analysis software (ImageJ) with identical processing parameters

  • Manually segment nuclear and cytoplasmic regions

  • Calculate nuclear/cytoplasmic fluorescence intensity ratio

  • Ensure blinding during analysis to prevent bias

• Controls:

  • Positive control: Cells treated with MTOR inhibitors (e.g., Torin)

  • Negative control: Nutrient-rich conditions

A reliable inter-rater reliability coefficient (Cronbach's alpha) should exceed 0.85 for semi-quantitative scoring methods .

What are the implications of TFEB clustering in neurodegenerative disease research?

TFEB clustering represents an important pathological feature in neurodegenerative diseases:

• Cluster characteristics:

  • Defined as TFEB-positive structures >0.7 μm in any direction

  • Located primarily in perinuclear cytoplasm

  • Observed in post-mortem tissue from Parkinson's disease patients

  • Distinct from normal cytoplasmic TFEB punctae

• Quantification methods:

  • Semi-quantitative scoring:

    • 0: No clusters

    • 1: Low (1-2 clusters)

    • 2: Intermediate (<10 clusters)

    • 3: Severe (>10 clusters)

  • Automated analysis: Custom ImageJ macros with consistent thresholds

• Research implications:

  • Significantly increased in sporadic PD/DLB compared to controls

  • Most pronounced in patients with GBA mutations

  • Present in both neurons with and without α-synuclein pathology

  • Potentially linked to cellular stress and lysosomal dysfunction

• Experimental models:

  • Observable in both post-mortem tissue and cellular models

  • Human embryonic stem cell-derived neurons (both wild-type and GBA-knockout) display similar clustering patterns under stress conditions

Why might I observe heterogeneous TFEB immunostaining patterns within the same tissue section?

Heterogeneous TFEB staining is commonly observed and reflects biological variability:

• Biological factors:

  • Cell-specific differences in metabolic state

  • Varying degrees of cellular stress

  • Different stages of cell cycle

  • Distinct microenvironmental conditions

• Technical considerations:

  • Antibody penetration issues in thicker sections

  • Fixation gradient effects in tissue

  • Epitope masking by post-translational modifications

• Interpretation strategies:

  • Analyze sufficient numbers of cells (>100 per condition)

  • Use quantitative scoring systems with defined criteria

  • Analyze heterogeneity itself as a potential biological variable

  • Consider co-labeling with markers for cellular stress or metabolic state

In neuromelanin-containing dopaminergic neurons, this heterogeneity is particularly prominent, with neighboring neurons showing different TFEB localization patterns even within the same subject .

How can I distinguish between specific and non-specific staining when using TFEB antibodies?

Distinguishing specific from non-specific staining requires methodical validation:

• Critical controls:

  • TFEB knockout or knockdown cells/tissues

  • Peptide competition assays

  • Multiple antibodies targeting different epitopes

  • Secondary-only controls

  • Isotype controls for monoclonal antibodies

• Validation criteria:

  • Consistent molecular weight in Western blot (~65-70 kDa)

  • Expected subcellular localization patterns

  • Responsiveness to known TFEB modulators (e.g., starvation, MTOR inhibitors)

  • Reduction of signal in knockdown models

• Cross-validation approaches:

  • Compare immunofluorescence with Western blot results

  • Use phospho-specific antibodies to confirm regulation

  • Utilize different antibodies recognizing distinct epitopes

For example, TFEB clusters observed in tissue specimens should be verified in cell culture models under similar conditions to confirm they are not artifacts of post-mortem tissue processing .

How does TFEB activation relate to B cell function and what antibody approaches best capture this relationship?

TFEB plays a significant role in B cell immune function:

• TFEB in B cell biology:

  • Acts as a BCR-controlled rheostat driving activation-induced apoptosis

  • Promotes reception of co-stimulatory rescue signals

  • Facilitates dark zone entry of light-zone-residing centrocytes in germinal centers

  • Regulates chemokine receptors and balances Bcl-2/BH3-only family members

• Antibody-based detection methods:

  • Flow cytometry for quantifying TFEB nuclear/cytoplasmic ratios

  • Immunofluorescence to visualize subcellular localization

  • Western blot to measure total TFEB expression levels

• Key findings:

  • BCR ligation triggers nuclear TFEB translocation

  • Antigen-experienced CD80+ B cells show higher nuclear TFEB than CD80- cells

  • TFEB expression and nuclear quantity elevated in CD80+ cells

  • Nuclear TFEB serves as a marker of both recent BCR stimulation and antigenic experience

• B cell subset analysis:

  • Present in IgD+, CD27+, CD38- memory B cell pools (~15%)

  • Present in switched (CD19+, IgD-, CD27+, CD38-) memory B cell pools (~15%)

  • Not detected in naïve B cells (CD19+, IgD+, CD27-, CD38-)

  • Not detected in plasmablasts (CD19+, IgD-, CD27+, CD38+)

These findings establish TFEB as a cross-isotype BCR-distal nuclear effector and an inter-species marker of antigen-experienced B cells .

How do phospho-specific TFEB antibodies enhance our understanding of TFEB regulation?

Phospho-specific antibodies provide crucial insights into TFEB regulation:

• Antibody development strategy:

  • Design antigen peptides with phosphorylation sites at N-terminal or C-terminal ends

  • This prevents interference between adjacent phosphorylation sites

  • Enables specific detection of single and dual phosphorylation events

• Specificity profiles:

  • p-S466 antibodies: detect p-S466 and p-S466/S467 peptides

  • p-S467 antibodies: specifically detect p-S467 peptide

  • p-S466/S467 antibodies: recognize p-S466/S467 and p-S467 peptides

  • p-S469 antibodies: specifically detect p-S469 peptide

• Applications:

  • Cell-free assays to evaluate TFEB phosphorylation by kinases like AMPK

  • Monitoring phosphorylation status in response to cellular stressors

  • Studying the interplay between different phosphorylation sites

• Technical limitations:

  • Some phospho-antibodies show limited sensitivity (e.g., p-S469)

  • Challenges in detecting endogenous TFEB phosphorylation in post-mortem tissue

  • Potential cross-reactivity with closely related family members

Understanding the phosphorylation status of TFEB is critical since it determines subcellular localization and transcriptional activity, with hypophosphorylated TFEB translocating to the nucleus to activate target genes .

What role does TFEB play in neurodegenerative diseases and how can TFEB antibodies advance this research?

TFEB dysfunction appears central to several neurodegenerative conditions:

• Parkinson's disease and DLB findings:

  • Reduced nuclear localization of TFEB in substantia nigra pars compacta dopaminergic neurons

  • Increased cytoplasmic TFEB clustering in disease cases compared to controls

  • More severe clustering in patients with GBA mutations

  • Observable in neurons both with and without α-synuclein pathology

• Experimental approaches:

  • Semi-quantitative scoring of nuclear TFEB localization

  • Quantification of TFEB clusters (count and area)

  • Co-labeling with α-synuclein phosphorylated at Ser129

• Technical considerations:

  • Use multiple antibodies targeting different epitopes

  • Apply standardized image acquisition settings

  • Implement blinded analysis to prevent bias

  • Quantify heterogeneity of TFEB patterns

• Research implications:

  • TFEB dysfunction may contribute to lysosomal impairment in neurodegeneration

  • Altered TFEB localization precedes or accompanies protein aggregation

  • TFEB activation could represent a therapeutic strategy

  • GBA mutations particularly affect TFEB function and localization

This research area continues to evolve, with TFEB antibodies serving as crucial tools for understanding the relationship between lysosomal function and neurodegeneration.

How can I design ChIP experiments using TFEB antibodies to identify novel target genes?

ChIP experiments with TFEB antibodies require careful design:

• Antibody selection:

  • Choose ChIP-validated antibodies (e.g., TFEB E5P9M Rabbit mAb)

  • Optimal antibody amount: 10 μl per immunoprecipitation

  • Recommended chromatin amount: 10 μg (~10^6 cells)

• Target sequence considerations:

  • TFEB binds E-box sequences (5'-CANNTG-3')

  • Specifically recognizes CLEAR-box sequence (5'-GTCACGTGAC-3') in lysosomal genes

  • Efficient binding requires dimerization with itself or other MiT/TFE family members

• Experimental controls:

  • Input chromatin (pre-immunoprecipitation)

  • IgG isotype control

  • Known TFEB target genes (positive controls)

  • Non-target regions (negative controls)

• Validation approaches:

  • Confirm targets with multiple TFEB antibodies

  • Perform ChIP under different cellular conditions (e.g., starvation, MTOR inhibition)

  • Combine with functional assays (e.g., reporter assays, gene expression analysis)

  • Consider TFEB knockout/knockdown controls