TCF19 Antibody

What is TCF19 and what are its key structural features?

TCF19 (Transcription Factor 19), also known as SC1 or SC1-1, is a 345 amino acid nuclear protein that functions as a transcriptional regulator. The protein contains three critical structural domains that enable its function: one forkhead-associated (FHA) domain, a proline-rich domain, and one PHD-type zinc finger. These domains are essential for TCF19's role in transcriptional regulation, particularly in controlling the expression of genes involved in cell cycle progression . The protein is primarily localized in the nucleus, where it exerts its regulatory functions on target genes. TCF19's expression pattern is tightly linked to the cell cycle, with significantly elevated levels observed during the G1-S phase transition, suggesting its critical involvement in cell proliferation mechanisms .

Which applications are TCF19 antibodies validated for?

TCF19 antibodies have been validated for multiple research applications, with varying degrees of optimization depending on the specific antibody clone and format. Based on the technical specifications provided by manufacturers, the following applications have been validated:

Most commercially available TCF19 antibodies demonstrate reliable performance in Western blot and ELISA applications, with immunohistochemistry and immunofluorescence requiring more careful optimization of staining protocols .

What species reactivity is available for TCF19 antibodies?

TCF19 antibodies vary in their species cross-reactivity. The most commonly available antibodies react with human TCF19, while some offer broader reactivity profiles. The search results indicate the following reactivity patterns:

• Human-specific TCF19 antibodies are most abundant, with numerous options available from different manufacturers

• Some antibodies offer cross-reactivity with mouse and rat TCF19, particularly the mouse monoclonal F-27 clone

• Select polyclonal antibodies demonstrate broader reactivity, including human, rat, mouse, and sometimes dog, horse, pig, and rabbit specimens

When selecting an antibody for cross-species applications, researchers should verify the homology of the immunogen sequence with the target species' TCF19 protein and request validation data specific to their species of interest .

What dilutions are recommended for different TCF19 antibody applications?

Optimal antibody dilutions vary by application and specific antibody formulation. Based on the technical information provided, these general recommendations can guide initial protocol development:

• Immunohistochemistry (IHC): 1:50-1:100 dilution range

• ELISA: 1:5000-1:10000 dilution range (for high sensitivity)

• Western Blot: Typically 1:1000, though this varies by antibody concentration (typically designed for 100 μg/ml stock solutions)

• Immunofluorescence: Often similar to IHC dilutions, approximately 1:50-1:200

Researchers should always perform antibody titration experiments to determine the optimal dilution for their specific experimental conditions, sample type, and detection method .

How does TCF19 function in cell cycle regulation and proliferation?

TCF19 serves as a critical trans-activating factor specifically regulating genes involved in late-stage cell cycle progression. Its expression peaks during the G1-S phase transition, coinciding with its regulatory role in promoting DNA replication and cell cycle advancement .

The protein functions primarily through its DNA-binding capabilities conferred by its PHD-type zinc finger domain, allowing it to selectively bind promoter regions of cell cycle-regulatory genes. TCF19 also facilitates the recruitment of transcriptional machinery through its proline-rich domain, which serves as a protein-protein interaction interface .

Research indicates that TCF19 depletion results in delayed S-phase entry and reduced proliferation rates in multiple cell types. This regulatory function appears to be conserved across mammalian species, with similar cell cycle-dependent expression patterns observed in human, mouse, and rat cell lines . The spatiotemporal regulation of TCF19 expression serves as a molecular switch that helps coordinate the precise timing of cell cycle transitions, particularly in rapidly dividing cell populations.

What is the role of TCF19 in T cell exhaustion and cancer immunotherapy resistance?

Recent research (March 2024) has identified a novel mechanism of tumor immune escape involving TCF19-expressing exhausted T cells. Investigators have characterized a specific subpopulation of terminally exhausted CD8+ T cells that express TCF19+PD1+TIM3+ markers . This cell population exhibits distinctive features:

• Low differentiation status despite being terminally exhausted

• High proliferative potential compared to other exhausted T cell subsets

• Expression of TCF19 alongside established exhaustion markers PD1 and TIM3

• Negative correlation with response to immune checkpoint blockade (ICB) therapy

Single-cell sequencing data from multiple cancer types (colorectal, gastric, melanoma, and lung cancers) revealed that the abundance of these TCF19+PD1+TIM3+ exhausted T cells was inversely proportional to the efficacy of ICB therapy. This observation suggests that these cells represent a significant mechanism of therapy resistance .

The generation of these cells appears to be regulated by E2F and MYC transcription factor families, providing potential targets for therapeutic intervention. Immunofluorescence staining and immunohistochemical analysis of patient samples confirmed the clinical relevance of this cell population in predicting immunotherapy outcomes .

What are the key considerations for selecting between monoclonal and polyclonal TCF19 antibodies?

The choice between monoclonal and polyclonal TCF19 antibodies should be guided by the specific research application and experimental requirements. Each antibody type offers distinct advantages:

Monoclonal TCF19 Antibodies:

• Provide consistent lot-to-lot reproducibility

• Recognize a single epitope, reducing background in some applications

• Often preferred for quantitative applications requiring high specificity

• Available options include the well-characterized F-27 clone (mouse IgG1 κ) and 6D8 clone

• Particularly suitable for applications requiring precise epitope targeting

Polyclonal TCF19 Antibodies:

• Recognize multiple epitopes, potentially increasing detection sensitivity

• May better tolerate minor protein denaturation or modifications

• Available from multiple host species (primarily rabbit, but also goat)

• Often purified by antigen affinity chromatography to >95% purity

• Useful for detecting proteins with low expression levels

For applications requiring detection of modified TCF19 or where protein conformation may be altered, polyclonal antibodies often provide greater flexibility. Conversely, for studies requiring precise epitope targeting or consistent batch performance over time, monoclonal antibodies may be preferable .

How is TCF19 implicated in pathological conditions such as psoriasis?

The TCF19 gene is located in a genomic region on chromosome 6 that has been strongly associated with psoriasis vulgaris susceptibility. This skin disorder is characterized by hyperproliferation of epidermal cells, creating the characteristic plaques and scales observed clinically .

The connection between TCF19 and psoriasis is mechanistically logical given TCF19's established role in regulating cell cycle progression, particularly the G1-S phase transition. The pathophysiology of psoriasis involves dysregulated keratinocyte proliferation, precisely the cellular process that TCF19 helps control .

Several lines of evidence support this association:

• Genetic mapping studies have identified the TCF19 locus as a psoriasis susceptibility region

• TCF19 expression is elevated in hyperproliferative skin conditions

• The regulatory effect of TCF19 on late cell cycle-specific genes aligns with the hyperproliferative phenotype observed in psoriatic lesions

• Altered TCF19 function could contribute to the accelerated keratinocyte turnover characteristic of psoriasis

This association suggests TCF19 may represent a potential therapeutic target for addressing the hyperproliferative component of psoriasis pathogenesis, although direct intervention strategies targeting this pathway remain in early research phases .

What validation methods should be employed to confirm TCF19 antibody specificity?

Rigorous validation of TCF19 antibody specificity is essential for generating reliable research data. Comprehensive validation should include multiple complementary approaches:

• Positive and negative control samples:

  • Positive: Cell lines with confirmed TCF19 expression (particularly during G1-S phase)

  • Negative: TCF19-knockout cells or tissues from TCF19-deficient models

  • Comparison of tissues with known differential expression patterns

• Peptide competition assays:

  • Pre-incubation of antibody with immunizing peptide should abolish specific signal

  • Non-related peptides should not affect antibody binding

• Molecular weight verification:

  • In Western blot applications, TCF19 should appear at approximately 345 amino acids (~38-40 kDa)

  • Multiple bands may indicate splice variants, post-translational modifications, or non-specific binding

• Orthogonal detection methods:

  • Correlation between protein detection and mRNA expression (qPCR)

  • Comparison of multiple antibodies targeting different epitopes

  • Verification with tagged recombinant TCF19 expression

• siRNA/shRNA knockdown:

  • Reduction in specific signal following TCF19 transcript depletion

  • Useful for confirming antibody specificity in cell culture systems

The most reliable validation combines multiple approaches and includes appropriate controls to distinguish specific from non-specific signals across different experimental conditions and detection methods .

How can detection of TCF19 be optimized in different applications?

Optimizing TCF19 detection requires application-specific considerations:

For Western Blot (WB):

• Sample preparation: Nuclear extraction protocols are preferred as TCF19 is primarily nuclear

• Denaturing conditions: Standard SDS-PAGE with reducing conditions is suitable

• Transfer conditions: Semi-dry or wet transfer methods both work effectively

• Blocking: 5% non-fat milk or BSA in TBST (Tris-buffered saline with 0.1% Tween-20)

• Primary antibody incubation: Overnight at 4°C yields optimal results

• Expected molecular weight: ~38-40 kDa band

For Immunohistochemistry (IHC-P):

• Antigen retrieval: Heat-induced epitope retrieval in citrate buffer (pH 6.0)

• Section thickness: 4-5 μm sections from formalin-fixed, paraffin-embedded tissues

• Blocking: 10% normal serum from the species of secondary antibody

• Primary antibody dilution: Start with 1:50-1:100 range

• Detection systems: Both DAB (3,3'-diaminobenzidine) and fluorescent secondary antibodies are suitable

• Nuclear counterstain: Hematoxylin for brightfield or DAPI for fluorescence

For Immunofluorescence (IF):

• Fixation: 4% paraformaldehyde (10-15 minutes) preserves TCF19 antigenicity

• Permeabilization: 0.2% Triton X-100 for nuclear access

• Blocking: 1-5% BSA with 10% normal serum

• Primary antibody: 1:50-1:200 dilution, overnight at 4°C

• Co-staining: Compatible with cell cycle markers for functional correlation

For ELISA:

• Coating: Direct coating of recombinant TCF19 or capture antibody approach

• Sample preparation: Nuclear extracts diluted in appropriate buffer

• Detection range: High sensitivity with 1:5000-1:10000 antibody dilution

• Standard curve: Recombinant TCF19 protein as reference standard

How should TCF19 antibodies be stored and handled to maintain optimal performance?

Proper storage and handling of TCF19 antibodies is critical for maintaining their performance characteristics over time:

Storage conditions:

• Temperature: Most formulations require -20°C for long-term storage

• Aliquoting: Divide antibody solution into single-use aliquots to avoid freeze-thaw cycles

• Working dilutions: Store at 4°C for up to 2 weeks; avoid prolonged storage of diluted antibody

Handling recommendations:

• Avoid repeated freeze-thaw cycles (limit to <5 cycles)

• Centrifuge vial briefly before opening to collect solution at the bottom

• For conjugated antibodies, protect from prolonged light exposure

• Allow antibody to equilibrate to room temperature before opening frozen vials

Reconstitution of lyophilized antibodies:

• Use sterile techniques and recommended buffer (typically PBS)

• Gently mix by inversion or rotation; avoid vigorous vortexing

• Allow complete dissolution before use (typically 30 minutes at room temperature)

Working dilution preparation:

• Use high-quality, freshly prepared buffers

• Include carrier protein (0.1-1% BSA) for diluted antibodies

• Consider adding preservatives (0.02% sodium azide) for solutions stored >24 hours

Following these storage and handling recommendations helps maintain antibody specificity and sensitivity, ensuring consistent experimental results over the product's shelf life .

What cell models are optimal for studying TCF19 function?

Selecting appropriate cell models is crucial for effectively studying TCF19 function. Based on TCF19's biological role and expression pattern, these cell systems are particularly suitable:

Proliferating cell lines:

• HeLa, HEK293, and other rapidly dividing immortalized cell lines express detectable TCF19

• Cell synchronization protocols (serum starvation, double thymidine block) allow capture of cell cycle-specific expression patterns

• Primary keratinocytes provide a relevant model for studying TCF19's potential role in skin disorders

Immune cell models:

• Primary CD8+ T cells for studying TCF19's role in T cell exhaustion

• Cancer cell and T cell co-culture systems to study TCF19+PD1+TIM3+ exhausted T cell development

• Tumor infiltrating lymphocyte (TIL) isolation from patient samples or mouse models

Disease-specific models:

• Psoriatic keratinocyte models (either primary cells from patients or induced models)

• Cancer cell lines with varying immunotherapy response profiles

• T cell exhaustion models using chronic stimulation protocols

Genetic manipulation approaches:

• CRISPR/Cas9-mediated TCF19 knockout cell lines

• Inducible TCF19 expression systems to study dose-dependent effects

• TCF19 reporter constructs for live-cell imaging of expression dynamics

The choice of model system should align with the specific research question, considering factors such as endogenous TCF19 expression levels, cell cycle characteristics, and relevance to the disease or biological process being investigated .

How does TCF19 relate to immune checkpoint blockade therapy resistance?

Recent research published in March 2024 has uncovered a significant role for TCF19 in mediating resistance to immune checkpoint blockade (ICB) therapy. This breakthrough finding characterizes a previously unrecognized population of terminally exhausted CD8+ T cells that express TCF19 along with PD1 and TIM3 (TCF19+PD1+TIM3+) .

These exhausted T cells exhibit several counterintuitive properties:

• Despite being terminally exhausted, they maintain a low differentiation state

• They retain high proliferative capacity, unlike other exhausted T cell subsets

• Their abundance inversely correlates with patient response to ICB therapy

The researchers employed cutting-edge techniques including:

• Single-cell RNA sequencing across multiple cancer types

• Bioinformatics analysis tools (CytoTRACE.T and CCAT.A) to calculate differentiation states

• GEO and KEGG pathway gene set enrichment analysis

• Multi-parameter immunofluorescence staining and flow cytometry for validation

• Correlation with patient immunotherapy response data

The formation of these TCF19+PD1+TIM3+ exhausted T cells appears to be regulated by E2F and MYC transcription factor families, suggesting potential targets for intervention. This discovery has significant clinical implications, as measuring the abundance of these cells could help predict ICB therapy response and guide treatment decisions .

Furthermore, this finding opens new therapeutic avenues focused on modulating TCF19 expression or function in exhausted T cells to potentially overcome resistance to immunotherapy in cancer patients.

What innovations in TCF19 antibody development are enhancing research capabilities?

The field of TCF19 antibody development has seen several innovations that enhance research capabilities:

• Expanded epitope targeting:

  • Antibodies targeting diverse epitopes across the TCF19 protein are now available

  • Options include antibodies recognizing N-terminal (AA 17-102), internal (AA 12-250), and C-terminal regions

  • This diversity enables detection of different TCF19 isoforms or post-translationally modified variants

• Increased species cross-reactivity:

  • Newer antibodies offer broader species reactivity profiles

  • Some polyclonal antibodies now detect TCF19 across seven species (human, rat, mouse, dog, horse, pig, rabbit)

  • This facilitates comparative studies across model organisms

• Validation across multiple applications:

  • Comprehensive validation across techniques (WB, ELISA, IF, IHC, IP, RNAi)

  • Application-specific optimization data is increasingly available

  • This reduces the need for extensive in-house validation

• Improved purification methods:

  • Antigen affinity purification yielding >95% purity

  • Reduced batch-to-batch variability

  • Enhanced specificity through removal of non-specific antibodies

• Specialized antibodies for cancer immunology:

  • Development of antibodies optimized for detecting TCF19 in immune cell subsets

  • Compatibility with multi-parameter immunofluorescence panels

  • Validated protocols for studying T cell exhaustion markers alongside TCF19

These innovations collectively enhance the toolkit available to researchers studying TCF19 function, enabling more precise and reliable detection across diverse experimental contexts and biological systems .