DCAF4L2 Antibody

What is DCAF4L2 and what is its function in cellular biology?

DCAF4L2 (DDB1 and CUL4 Associated Factor 4-Like 2), also known as WD repeat domain 21C (WDR21C), is a member of the WD-repeat protein family. These proteins primarily function as mediators of protein-protein interactions and are frequently found in E3 ligase CRL4 complexes .

DCAF4L2 forms an E3 ligase complex with Cul4A and DDB1, specifically acting as the substrate recognition component of this complex. This E3 ligase complex mediates the degradation of PPM1B, a negative regulator of NFκB signaling . Through this mechanism, DCAF4L2 promotes epithelial-mesenchymal transition (EMT) and enhances cell migration and invasion, particularly in colorectal cancer cells .

The protein contains only a WD-repeat domain, which serves as a platform for assembling protein complexes . Research has shown that DCAF4L2 is minimally expressed in normal colorectal tissues but shows significantly elevated expression in colorectal cancer tissues .

How does DCAF4L2 contribute to cancer progression based on current research?

DCAF4L2 has been identified as a key player in colorectal cancer (CRC) progression through several mechanisms:

• Promotion of EMT: DCAF4L2 activates the NFκB signaling pathway by targeting PPM1B for degradation, subsequently promoting epithelial-mesenchymal transition, which is critical for cancer cell invasion and metastasis .

• Enhanced cell migration and invasion: Experimental studies have demonstrated that overexpression of DCAF4L2 in CRC cell lines (SW480 and SW620) significantly enhances migration and invasion capabilities, while knockdown of DCAF4L2 in cell lines with high endogenous expression (SW1116 and HT-29) attenuates these abilities .

• Clinical correlation with metastasis: Elevated DCAF4L2 expression in CRC patients positively correlates with lymphatic and distant metastasis and advanced TNM stage . As shown in the clinical data below:

• Prognostic value: Kaplan-Meier analysis has shown that CRC patients with higher DCAF4L2 expression have significantly shorter survival times, establishing DCAF4L2 as an independent prognostic factor for poor survival .

Interestingly, while DCAF4L2 significantly affects cell migration and invasion, research has found no apparent effects on cell proliferation, apoptosis, or necrosis .

What applications are DCAF4L2 antibodies validated for, and which one should I select for my experiment?

DCAF4L2 antibodies have been validated for multiple applications, with varying specificities depending on the manufacturer and clone. Based on the search results, the most common applications include:

For selection criteria:

• For Western blotting: Choose antibodies specifically validated for WB with published examples. Antibodies recognizing the N-terminal region are often preferred for detecting full-length protein .

• For IHC: Select antibodies with demonstrated specificity in tissue sections, preferably with positive controls from colorectal cancer tissues .

• For mechanistic studies: Consider antibodies that have been used successfully in immunoprecipitation experiments, particularly those that have been validated in the Cul4A-DDB1 complex studies .

Always perform proper validation in your experimental system before proceeding with large-scale experiments, as antibody performance can vary across different tissue types and experimental conditions.

What are the optimal protocols for immunoprecipitation of DCAF4L2 when studying protein-protein interactions?

Based on successful protocols from the published literature, the following methodology is recommended for immunoprecipitation of DCAF4L2 when studying its interactions with other proteins:

Flag-tagged pulldown protocol:

• Cell preparation:

  • Infect cells (e.g., SW480 colorectal cancer cells) with DCAF4L2 lentivirus

  • After 7 days of hygromycin selection, establish stable overexpression cell lines

  • Harvest approximately 2.5×10⁸ cells and lyse at 4°C

• Pre-clearing:

  • Incubate cell lysates with IgG beads for 2 hours at 4°C

  • Centrifuge at 5,000 RPM for 10 minutes

  • Save 20 μl of the supernatant as "Flag-Input" control

• Immunoprecipitation:

  • Add anti-Flag M2 affinity beads (pre-washed with TBS buffer 3 times) to the remaining cell lysate

  • Gently rotate overnight at 4°C

  • Centrifuge for 2 minutes at 5,000 RPM and collect Flag-M2 beads

• Washing and elution:

  • Wash beads 3 times in TBS

  • Elute with Flag-peptide by incubating for 5 minutes at room temperature with gentle tapping

  • Centrifuge for 30 seconds and transfer supernatants to fresh tubes

• Analysis:

  • Proceed with mass spectrometry or western blotting to identify interacting proteins

  • For studying specific interactions (e.g., with DDB1, PPM1B), use co-immunoprecipitation followed by western blotting with antibodies against the putative interacting proteins

For studying DCAF4L2 interactions with DDB1 and Cul4A specifically, co-transfection of expression constructs in HEK293T cells followed by co-immunoprecipitation has been successfully employed .

How do I design experiments to validate DCAF4L2 as a therapeutic target in metastatic colorectal cancer?

To validate DCAF4L2 as a therapeutic target in metastatic colorectal cancer, a comprehensive experimental approach should include:

• Clinical validation of expression correlation:

  • Analyze DCAF4L2 expression in a large cohort of CRC patients with complete clinical follow-up data

  • Perform tissue microarray with immunohistochemistry using validated anti-DCAF4L2 antibodies

  • Correlate expression with clinicopathological features, particularly metastasis status and patient survival

• Functional validation in vitro:

  • Establish stable DCAF4L2 knockdown and overexpression cell lines in multiple CRC cell lines

  • Perform comprehensive phenotypic assays focusing on:

    • Migration (wound healing assay)

    • Invasion (matrigel invasion assay)

    • EMT marker expression (E-cadherin, N-cadherin, FN1, ZO1 by western blotting)

• Pathway analysis:

  • Examine the effects on NFκB signaling using:

    • Dual luciferase reporter assay for NFκB activity

    • Western blotting for phosphorylated IκB and nuclear translocation of p65

    • Evaluation of PPM1B protein levels and ubiquitination status

• In vivo metastasis models:

  • Develop orthotopic xenograft models using DCAF4L2-modified cells

  • Assess metastatic burden in liver and lymph nodes

  • Validate target engagement using immunohistochemistry

• Therapeutic targeting approach:

  • Design small molecule inhibitors or peptides that disrupt DCAF4L2-DDB1 interaction

  • Test compounds in vitro using purified protein binding assays

  • Validate in cell-based assays by examining PPM1B degradation and NFκB activation

  • Evaluate anti-metastatic efficacy in preclinical models

• Biomarker development:

  • Develop a clinical assay to quantify DCAF4L2 expression in patient samples

  • Correlate expression with response to potential DCAF4L2-targeting therapies

  • Explore combination with standard-of-care treatments for metastatic CRC

The experimental design should include appropriate controls at each step and employ multiple cell lines representing different CRC molecular subtypes to ensure robust and clinically relevant findings.

What are the optimal methodologies for investigating DCAF4L2's role in the ubiquitin-proteasome system?

Investigating DCAF4L2's role in the ubiquitin-proteasome system requires specialized techniques to analyze E3 ligase function, substrate recognition, and protein degradation. Based on successful approaches in the literature, the following methodologies are recommended:

• In vitro ubiquitination assays:

  • Reconstitution of E3 ligase complex: Express and purify recombinant DCAF4L2, DDB1, and Cul4A proteins (using bacterial or baculovirus expression systems)

  • Ubiquitination reaction: Combine purified E1, E2 (typically UbcH5), the reconstituted E3 complex, ubiquitin, ATP, and the putative substrate (e.g., PPM1B)

  • Detection: Analyze ubiquitination by western blotting with anti-ubiquitin and substrate-specific antibodies

• Cellular ubiquitination assays:

  • Co-transfection approach: Transfect cells with DCAF4L2, HA-tagged ubiquitin, and putative substrate

  • MG132 treatment: Add proteasome inhibitor (10 μM for 4-6 hours) to prevent degradation of ubiquitinated proteins

  • Lysis under denaturing conditions: Use 1% SDS buffer with boiling to disrupt non-covalent interactions

  • Immunoprecipitation: Pull down the substrate and detect ubiquitination with anti-HA antibody

• Protein stability and half-life measurements:

  • Cycloheximide chase assay: Treat cells with cycloheximide to inhibit new protein synthesis

  • Time-course analysis: Collect samples at various time points (0, 2, 4, 8 hours)

  • Protein level detection: Perform western blotting to measure substrate protein levels

  • Comparative analysis: Compare substrate stability in DCAF4L2 wildtype, overexpression, and knockdown conditions

• Substrate identification:

  • Immunoprecipitation-mass spectrometry: Use Flag-tagged DCAF4L2 pulldown followed by mass spectrometry

  • Stable isotope labeling by amino acids in cell culture (SILAC): Compare protein levels in DCAF4L2 wildtype vs. knockout cells

  • Ubiquitin remnant profiling: Enrich for ubiquitinated peptides using K-ε-GG antibodies followed by mass spectrometry

• Structure-function analysis:

  • Domain mapping: Generate DCAF4L2 truncation or point mutants to identify regions required for substrate recognition and DDB1 binding

  • Co-immunoprecipitation: Test the ability of mutants to bind DDB1, Cul4A, and substrates

  • Functional assays: Assess ubiquitination activity and substrate degradation with mutant constructs

A comprehensive analysis would combine these approaches to establish DCAF4L2's role in substrate recognition, the mechanism of ubiquitin transfer, and the physiological consequences of substrate degradation.

Why might I observe inconsistent DCAF4L2 detection across different cell lines, and how can I optimize antibody performance?

Inconsistent DCAF4L2 detection across different cell lines can occur for several biological and technical reasons. Here are potential explanations and optimization strategies:

Biological factors affecting detection:

• Variable expression levels: DCAF4L2 expression varies significantly across cell types. Research shows almost no expression in normal colorectal tissues but elevated expression in CRC cell lines, with SW1116 and HT-29 showing notably higher levels than SW480 and SW620 .

• Post-translational modifications: DCAF4L2 may undergo different modifications in various cell types, potentially affecting epitope recognition.

• Protein complex formation: As DCAF4L2 forms complexes with DDB1 and Cul4A, these interactions might mask antibody epitopes in certain cell contexts.

Technical optimization strategies:

• Sample preparation optimization:

  • Lysis buffer selection: For E3 ligase complex components, use RIPA buffer supplemented with deubiquitinase inhibitors (N-ethylmaleimide, 10 mM)

  • Protease inhibitors: Always include fresh, complete protease inhibitor cocktail

  • Sample handling: Maintain samples on ice and process quickly to prevent degradation

• Antibody selection and validation:

  • Epitope consideration: Select antibodies targeting different epitopes (N-terminal vs. internal regions)

  • Validation in positive control: Always include a cell line with known high expression (e.g., HT-29 for DCAF4L2)

  • Recombinant protein control: Include purified DCAF4L2 protein as a positive control

• Western blot protocol optimization:

  • Loading amount: Increase protein loading (50-100 μg) for cell lines with low expression

  • Blocking optimization: Test different blocking agents (5% milk vs. 5% BSA)

  • Antibody concentration: Titrate primary antibody (1:500 to 1:2000) to find optimal signal-to-noise ratio

  • Incubation conditions: Try overnight incubation at 4°C for primary antibody

  • Detection system: Use high-sensitivity ECL or fluorescent secondary antibodies for low abundance proteins

• Alternative detection approaches:

  • Immunoprecipitation before Western blot: Enrich DCAF4L2 by IP before detection

  • RT-qPCR validation: Confirm mRNA expression levels to correlate with protein detection

  • Overexpression control: Include DCAF4L2-overexpressing cells as positive controls

By systematically addressing these factors, researchers can optimize DCAF4L2 detection across different experimental systems.

How can I verify DCAF4L2 antibody specificity and rule out non-specific binding in my experimental system?

Verifying antibody specificity is crucial for obtaining reliable results, especially for proteins like DCAF4L2 where commercial antibodies may vary in quality. Here are comprehensive approaches to validate DCAF4L2 antibody specificity:

• Genetic validation approaches:

  • Knockdown/knockout controls: Perform shRNA knockdown or CRISPR-Cas9 knockout of DCAF4L2 and confirm reduced or absent signal

  • Overexpression controls: Include cells overexpressing tagged DCAF4L2 (Flag-tagged or GFP-tagged) and verify co-localization or co-detection with the antibody

  • Rescue experiments: Re-express DCAF4L2 in knockout cells and confirm signal restoration

• Biochemical validation:

  • Peptide competition assay: Pre-incubate antibody with excess immunizing peptide before application; specific signals should be blocked

  • Multiple antibody comparison: Use antibodies from different sources targeting distinct epitopes; true signals should be consistent

  • Immunoprecipitation-Western blot: Perform IP with one antibody and detect with another targeting a different epitope

  • Molecular weight verification: DCAF4L2 has a molecular weight of approximately 43.7 kDa; confirm correct band size

• Orthogonal detection methods:

  • Mass spectrometry verification: Perform IP followed by mass spectrometry to confirm DCAF4L2 identity

  • RNA-protein correlation: Compare protein detection with RT-qPCR results across cell lines; patterns should correlate

  • Immunofluorescence co-localization: With known interactors like DDB1 or Cul4A

• Controls for specific applications:

  • For Western blotting:

    • Include recombinant DCAF4L2 protein as positive control

    • Test multiple blocking agents to reduce non-specific binding

    • Use gradient gels to better resolve proteins of similar size

  • For immunohistochemistry:

    • Include tissue samples known to be negative for DCAF4L2

    • Perform antigen retrieval optimization

    • Use different detection systems to confirm specificity

  • For immunoprecipitation:

    • Include IgG control to identify non-specific binding

    • Perform stringent washes with increased salt concentration

    • Use cross-linking if appropriate to stabilize interactions

By implementing these validation approaches, researchers can confidently establish the specificity of their DCAF4L2 antibody and distinguish true signals from experimental artifacts.

What are the emerging areas of research on DCAF4L2 beyond colorectal cancer, and how might antibody-based approaches contribute?

While DCAF4L2 has been extensively studied in colorectal cancer, emerging research is exploring its roles in other biological contexts. Current frontier areas and potential antibody-based approaches include:

• Other cancer types:

  • Liver cancer: DCAF4L2 has been reported to be amplified in liver cancer, suggesting a potential oncogenic role beyond CRC

  • Lung cancer: Preliminary evidence suggests DCAF4L2 amplification in lung cancer as well

  Antibody applications: Tissue microarrays with DCAF4L2 antibodies could elucidate expression patterns across multiple cancer types and correlate with clinical outcomes.

• Developmental biology:

  • Cleft palate: DCAF4L2 has been implicated in cleft palate pathogenesis, suggesting a role in embryonic development

  Antibody applications: Immunohistochemistry in developmental tissues could map DCAF4L2 expression during organogenesis and craniofacial development.

• E3 ligase function and substrate specificity:

  • Beyond PPM1B, DCAF4L2 likely targets other substrates for ubiquitination and degradation

  Antibody applications: Immunoprecipitation coupled with mass spectrometry using specific DCAF4L2 antibodies could identify novel substrates and interaction partners.

• DNA damage response pathways:

  • Other DCAFs are involved in DNA damage response, and DCAF4L2 may have similar functions

  Antibody applications: Chromatin immunoprecipitation (ChIP) using DCAF4L2 antibodies could reveal potential chromatin associations following DNA damage.

• Therapeutic targeting:

  • Development of proteolysis-targeting chimeras (PROTACs) directed at DCAF4L2-dependent degradation

  Antibody applications: Conformation-specific antibodies could help validate PROTAC-induced conformational changes in the CRL4-DCAF4L2 complex.

• Biomarker development:

  • DCAF4L2 expression as a prognostic or predictive biomarker in multiple cancer types

  Antibody applications: Development of highly specific monoclonal antibodies for clinical immunohistochemistry assays that could be used in pathology diagnostics.

Future directions should explore the broader significance of DCAF4L2 in cellular homeostasis and disease beyond its established role in colorectal cancer migration and invasion.

How can DCAF4L2 antibodies be integrated into high-throughput screening approaches for drug discovery?

DCAF4L2 antibodies can be strategically integrated into various high-throughput screening (HTS) platforms for drug discovery targeting the DCAF4L2-DDB1-Cul4A E3 ligase complex or its downstream effects:

• Proximity-based interaction screening:

  • AlphaScreen/AlphaLISA: Conjugate DCAF4L2 antibodies to donor beads and DDB1 antibodies to acceptor beads to screen for compounds disrupting their interaction

  • FRET/BRET-based assays: Develop assays using antibody fragments fused to fluorescent proteins to detect conformation changes or binding events

  • Split luciferase complementation: Create reporter systems using DCAF4L2 and substrate fusion proteins to monitor real-time interaction dynamics in live cells

• Degradation and stabilization screens:

  • High-content imaging: Use fluorescently labeled DCAF4L2 antibodies to track protein localization and levels in response to compound libraries

  • ELISA-based approaches: Develop sandwich ELISA systems using DCAF4L2 and PPM1B antibodies to measure substrate degradation

  • Cellular thermal shift assays (CETSA): Combine with DCAF4L2 antibodies to identify compounds stabilizing DCAF4L2 conformation

• Functional screening platforms:

  • Pathway reporter assays: Use NFκB luciferase reporters combined with immunoblotting using DCAF4L2 and PPM1B antibodies to correlate compound effects with target engagement

  • Phenotypic migration/invasion screens: Couple with DCAF4L2 immunostaining to confirm mechanism of action for hits from phenotypic screens

• PROTAC development:

  • Screen PROTAC libraries using DCAF4L2 antibodies to detect recruitment to specific targets

  • Monitor target protein degradation by immunoblotting or in-cell western

  • Validate mechanism by immunoprecipitation to detect neo-complex formation

• Compound library design and optimization:

  • Establish structure-activity relationships (SAR) by correlating compound structure with DCAF4L2 complex disruption detected by antibody-based methods

  • Use antibody epitope mapping to identify critical binding interfaces for targeted compound design

• In vivo pharmacodynamic assays:

  • Develop immunohistochemistry protocols to assess target engagement in xenograft models

  • Measure downstream biomarkers (EMT markers, PPM1B levels) that correlate with DCAF4L2 inhibition

A concrete implementation example would be a FRET-based HTS assay where:

• DCAF4L2 is tagged with a donor fluorophore

• A specific antibody fragment against PPM1B is labeled with an acceptor fluorophore

• Compounds disrupting DCAF4L2-mediated PPM1B degradation would decrease FRET signal, identifying potential therapeutic candidates

Integration of these antibody-based approaches into HTS workflows would accelerate the discovery of compounds targeting the DCAF4L2 pathway for potential cancer therapeutics.