HNRNPUL2 Antibody

What is the molecular weight of HNRNPUL2 and why might it appear different on Western blots?

HNRNPUL2 has a calculated molecular weight of approximately 85 kDa, but it frequently appears at 100-110 kDa on Western blots. This discrepancy occurs due to post-translational modifications and the protein's structural properties.

Western blot data from various antibody suppliers confirm this observation:

When optimizing your Western blot protocol for HNRNPUL2 detection, prepare to visualize bands between 85-110 kDa depending on the cell type and antibody used .

What applications are HNRNPUL2 antibodies validated for?

HNRNPUL2 antibodies have been validated for multiple experimental applications, with different antibodies showing utility across various techniques:

Select an antibody that has been specifically validated for your application of interest. For example, if performing immunofluorescence studies, antibodies like 20143-1-AP or ab220849 would be appropriate choices based on validation data .

How do I validate the specificity of an HNRNPUL2 antibody?

To validate HNRNPUL2 antibody specificity:

• Positive and negative controls: Use cell lines with known HNRNPUL2 expression (HeLa, HEK-293, Jurkat) as positive controls. For negative controls, use HNRNPUL2 knockdown cell lines .

• Western blot validation: Look for a single band at 85-110 kDa in your samples. Multiple bands may indicate non-specific binding .

• Blocking peptide experiments: Compare antibody staining with and without pre-incubation with the immunizing peptide. Specific staining should be eliminated in the blocked sample, as demonstrated in immunohistochemistry analysis of human breast carcinoma tissue .

• Orthogonal validation: Use orthogonal methods like RNAseq correlation to validate antibody specificity against transcript levels, as performed for the Sigma HPA041632 antibody .

• Cross-reactivity testing: If working with multiple species, confirm species cross-reactivity experimentally rather than relying solely on sequence homology predictions .

How does HNRNPUL2 interact with topoisomerase IIα and what implications does this have for DNA damage research?

HNRNPUL2 has been identified as an interaction partner of topoisomerase IIα, a key regulator of DNA topology and target for chemotherapeutic drugs. This interaction has significant implications for DNA damage research:

• Co-localization evidence: Immunofluorescence analysis reveals that HNRNPUL2 dynamically co-localizes with both isoforms of topoisomerase II within regions of condensed chromatin throughout the cell cycle .

• Functional relationship: HNRNPUL2 expression levels positively correlate with topoisomerase II activity. Research has demonstrated that:

  • HNRNPUL2 overexpression enhances topoisomerase II activity

  • HNRNPUL2 knockdown reduces topoisomerase II activity

• Methodology for studying this interaction:

  • Co-immunoprecipitation experiments using HNRNPUL2 antibodies can pull down topoisomerase IIα

  • Fluorescence microscopy with dual staining for HNRNPUL2 and topoisomerase II can visualize co-localization patterns

  • Chromatin immunoprecipitation (ChIP) can identify genomic regions where both proteins associate

• Implications for DNA damage research: This interaction suggests HNRNPUL2 may serve as a link between DNA topology management and genomic integrity preservation. Researchers investigating DNA damaging agents that target topoisomerase II (like etoposide) should consider HNRNPUL2's role in modulating cellular responses to these agents .

What is HNRNPUL2's role in the DNA damage response, and how can it be studied?

HNRNPUL2 plays multiple roles in the DNA damage response (DDR):

• Enhancement of DNA repair: Cells overexpressing HNRNPUL2 repair DNA double-strand breaks more quickly than control cells, as measured by γH2AX phosphorylation kinetics .

• Dynamic response to DNA damage:

  • HNRNPUL2 levels increase in the nucleus following DNA damage

  • The rate of increase is proportional to the severity of genotoxic insult

  • HNRNPUL2 is partially recruited to DNA damage sites, colocalizing with a subset of γH2AX foci

• Experimental approaches to study HNRNPUL2 in DDR:

  Technique	Application	Key Findings
  Immunofluorescence	Localization studies	HNRNPUL2 changes morphology and colocalizes with γH2AX foci during DNA damage
  Western blot	Expression level analysis	HNRNPUL2 levels increase after DNA damage induction
  Cell proliferation assays	Functional assessment	HNRNPUL2 expression influences proliferation rates in the presence of DNA damaging agents
  γH2AX quantification	DNA repair kinetics	HNRNPUL2 overexpression accelerates the resolution of γH2AX foci

• Recommended methodology for studying HNRNPUL2 in DDR:

  • Use defined DNA damaging agents (e.g., bleomycin, etoposide) at standardized concentrations

  • Monitor both HNRNPUL2 levels and localization at multiple timepoints after damage

  • Employ automated image analysis software for quantitative assessment of nuclear HNRNPUL2 dynamics

How do I optimize HNRNPUL2 antibody-based techniques for chromatin association studies?

HNRNPUL2 has been experimentally validated to possess chromatin binding properties. To optimize chromatin association studies:

• Cell fixation considerations:

  • For immunofluorescence: Use paraformaldehyde (PFA) fixation (typically 4%) followed by Triton X-100 permeabilization to preserve chromatin architecture while enabling antibody access

  • For chromatin fractionation: Use established protocols that separate soluble nuclear proteins from chromatin-bound fractions

• Antibody selection and dilution:

  • For immunofluorescence of chromatin-bound HNRNPUL2: ab220849 at 4 μg/mL has been validated for MCF7 cells

  • For Western blot analysis of chromatin fractions: ab195338 at 0.1 μg/mL provides clear detection

• Controls for chromatin association:

  • Positive control: Include known chromatin-associated proteins (e.g., histones)

  • Negative control: Include known non-chromatin nuclear proteins

  • Treatment control: α-Amanitin treatment alters the distribution of HNRNPUL2 and can serve as a functional control

• Advanced techniques for studying HNRNPUL2-chromatin interactions:

  • Chromatin immunoprecipitation (ChIP) to identify genomic binding sites

  • Proximity ligation assay (PLA) to visualize interactions with other chromatin proteins in situ

  • FRAP (Fluorescence Recovery After Photobleaching) to study dynamics of HNRNPUL2-chromatin association

What methods are effective for studying HNRNPUL2's interaction with RNA and R-loops?

HNRNPUL2 has been identified as playing a role in RNA splicing, transport, and stability, as well as in the promotion of complex loading in cohesin-independent STAG proteins that interact with RNA and R-loops . To investigate these interactions:

• RNA immunoprecipitation (RIP):

  • Validated protocol: RIP assay using antibodies against HNRNPUL2 has successfully demonstrated interaction with the long non-coding RNA CRNDE in DLD1 cells

  • Significant RNA enrichment was observed using HNRNPUL2 antibody compared to IgG control

• RNA pull-down experiments:

  • Protocol: RNA pull-down followed by SDS-PAGE and mass spectrometry has identified HNRNPUL2 as an RNA-binding protein

  • This approach revealed HNRNPUL2 as the most abundant protein interacting with CRNDE, a long non-coding RNA involved in colorectal carcinoma

• R-loop detection methods:

  • Immunofluorescence using S9.6 antibody (which recognizes RNA:DNA hybrids) in combination with HNRNPUL2 antibodies

  • DNA:RNA hybrid immunoprecipitation (DRIP) followed by HNRNPUL2 ChIP to identify regions where both R-loops and HNRNPUL2 are present

• Functional studies:

  • Transcription inhibition experiments: α-Amanitin treatment alters HNRNPUL2 distribution, suggesting a relationship between transcription activity and HNRNPUL2 localization

  • HNRNPUL2 knockdown or overexpression followed by RNA-seq to identify affected transcripts

Why might I observe variability in HNRNPUL2 antibody staining patterns in immunofluorescence?

Variability in HNRNPUL2 immunofluorescence staining can result from several factors:

• Cell cycle-dependent localization: HNRNPUL2 dynamically colocalizes with chromatin and topoisomerase II throughout the cell cycle, meaning cells at different cycle stages will show different staining patterns .

• Transcriptional state effects: HNRNPUL2 localization is influenced by transcription. α-Amanitin treatment (which inhibits transcription) alters HNRNPUL2 distribution, suggesting transcription activity affects localization patterns .

• DNA damage response: HNRNPUL2 changes morphology and distribution upon DNA damage induction, partially colocalizing with γH2AX foci. Inadvertent DNA damage during sample processing can affect staining patterns .

• Technical considerations:

  • Fixation method: Overfixation can mask epitopes

  • Antibody concentration: Titration is essential for optimal signal-to-noise ratio

  • Permeabilization: Adequate permeabilization is needed for nuclear protein detection

To address variability, synchronize cells when possible, control for DNA damage, and implement standardized fixation and staining protocols.

What controls should be included when using HNRNPUL2 antibodies for experimental studies?

For robust HNRNPUL2 antibody-based experiments, include these controls:

• Antibody specificity controls:

  • Blocking peptide experiment: Pre-incubate antibody with immunizing peptide to confirm specificity

  • HNRNPUL2 knockdown cells as negative control

  • Secondary antibody-only control to assess background

• Sample-specific controls:

  • Positive control cell lines: HeLa, 293T, Jurkat (human); TCMK-1, NIH/3T3 (mouse)

  • Fractionation controls for nuclear/cytoplasmic separation experiments

  • Loading controls appropriate for the technique (e.g., β-actin for Western blot)

• Experimental condition controls:

  • For DNA damage studies: Include timepoint series and damage-free controls

  • For transcription inhibition: Include vehicle-only controls alongside α-Amanitin treatment

  • For cell cycle studies: Include synchronized cell populations

• Cross-reactivity controls:

  • When working with multiple species, include species-specific positive controls

  • Validate cross-reactivity experimentally rather than relying solely on sequence homology

How can I investigate the role of HNRNPUL2 in linking DNA topology management with genomic integrity?

HNRNPUL2 functions at the interface of DNA topology and genomic integrity. To investigate this role:

• Combined knockdown/inhibition studies:

  • Perform HNRNPUL2 knockdown with siRNA/shRNA

  • Treat with topoisomerase II inhibitors (e.g., etoposide)

  • Assess DNA damage response through γH2AX foci formation and resolution

  • Compare single treatments versus combined treatment effects

• Protein-protein interaction analysis:

  • Co-immunoprecipitation of HNRNPUL2 with topoisomerase II

  • Proximity ligation assay to visualize interactions in situ

  • Domain mapping to identify interaction regions

  • Mutational analysis to disrupt specific interactions

• Functional assays:

  • Decatenation assays to measure topoisomerase II activity in the presence/absence of HNRNPUL2

  • Comet assay to measure DNA breaks

  • Cell cycle analysis to assess checkpoint activation

  • Cell proliferation/survival assays in the context of DNA damaging agents

• Chromatin dynamics studies:

  • ChIP-seq for HNRNPUL2 and topoisomerase II to identify co-occupied genomic regions

  • Hi-C or related techniques to assess chromatin topology changes upon HNRNPUL2 manipulation

  • Live-cell imaging of fluorescently tagged HNRNPUL2 during DNA damage response

What known post-translational modifications affect HNRNPUL2 function and antibody recognition?

While specific post-translational modifications (PTMs) of HNRNPUL2 are not extensively documented in the provided search results, several observations suggest their importance:

• Molecular weight discrepancy: The calculated molecular weight of HNRNPUL2 is 85 kDa, but it often appears at 100-110 kDa in Western blots, suggesting extensive post-translational modifications .

• PTM-specific antibodies: Currently, most available antibodies detect total HNRNPUL2 rather than specific PTMs. For example:

  • Sigma HPA041632 is described as detecting "unmodified" HNRNPUL2

  • ABIN1534977 detects "endogenous levels of total HNRNPUL2 protein"

• Research considerations:

  • When investigating PTMs, consider phosphorylation, which often affects nuclear proteins involved in DNA damage response

  • Use phosphatase treatments before Western blotting to determine if phosphorylation contributes to the higher observed molecular weight

  • Consider SUMOylation and ubiquitination, which are common modifications of nuclear proteins involved in DNA repair

• Methodology for PTM detection:

  • Immunoprecipitate HNRNPUL2 and analyze by mass spectrometry for PTM identification

  • Use PTM-specific antibodies (if/when available) alongside total HNRNPUL2 antibodies

  • Utilize phosphatase or deubiquitinase treatments to assess modification contributions to function

How can quantitative image analysis be optimized for HNRNPUL2 studies?

Advanced image analysis is crucial for extracting meaningful data from HNRNPUL2 immunofluorescence studies:

• Automated analysis approaches:

  • Allen et al. (2015) developed specialized software for quantitatively describing 3D immunofluorescence microscopy images of cell nuclei

  • This approach enables population statistics for parameters including colocalization and staining intensity

  • The software revealed that HNRNPUL2 levels increase in the nucleus following DNA damage proportionally to damage severity

• Key parameters for HNRNPUL2 quantification:

  • Nuclear intensity measurements: Total, mean, and distribution

  • Colocalization with markers (e.g., γH2AX, topoisomerase II)

  • Morphological features (HNRNPUL2 changes morphology after DNA damage)

  • Spatial distribution within the nucleus

• Recommended workflow:

  Analysis Stage	Tools/Methods	Considerations
  Image acquisition	Confocal microscopy	Z-stacks for 3D analysis, consistent exposure
  Preprocessing	Background subtraction, deconvolution	Maintain signal integrity
  Segmentation	Nuclear mask creation	DAPI or similar nuclear stain as reference
  Feature extraction	Intensity, texture, colocalization measurements	Extract multiple parameters per cell
  Statistical analysis	Population statistics across treatments	Account for cell-to-cell variability

• Validation of findings:

  • Perform orthogonal biochemical assays to confirm imaging findings

  • Include multiple biological replicates with large cell numbers

  • Use appropriate statistical tests for population-level comparisons

This comprehensive approach to quantitative imaging provides robust data on HNRNPUL2 dynamics in response to various cellular conditions.

What are the optimal storage and handling conditions for HNRNPUL2 antibodies?

For maximum stability and performance of HNRNPUL2 antibodies:

• Storage temperature:

  • Store antibodies at -20°C for long-term storage

  • Most commercial HNRNPUL2 antibodies are stable at this temperature for at least 1 year

• Buffer formulation:

  • Most HNRNPUL2 antibodies are supplied in phosphate buffered saline (PBS)

  • They typically contain preservatives such as sodium azide (0.02%) and stabilizers like glycerol (50%)

  • Some formulations include BSA (0.1-0.5%) as an additional stabilizer

• Handling precautions:

  • Avoid repeated freeze-thaw cycles which can degrade antibody performance

  • For antibodies not containing glycerol, consider aliquoting before storage

  • For glycerol-containing formulations (most common for HNRNPUL2 antibodies), aliquoting is generally unnecessary for -20°C storage

  • Note that sodium azide is a hazardous substance and should be handled by trained staff only

• Shipping considerations:

  • Most suppliers ship HNRNPUL2 antibodies with wet ice or cold packs

  • If small volumes become entrapped in the vial cap during shipping, briefly centrifuge to dislodge

What are the optimal fixation and permeabilization methods for HNRNPUL2 immunostaining?

To achieve optimal HNRNPUL2 detection in immunocytochemistry and immunohistochemistry:

• For cultured cells (ICC/IF):

  • Fixation: 4% paraformaldehyde (PFA) has been validated for HNRNPUL2 detection

  • Permeabilization: Triton X-100 effectively permeabilizes cells for nuclear protein detection

  • Example protocol: PFA-fixed, Triton X-100 permeabilized MCF7 cells have been successfully stained using ab220849 at 4 μg/mL

• For tissue sections (IHC):

  • Paraffin embedding: Standard formalin-fixed paraffin-embedded (FFPE) protocols are compatible with HNRNPUL2 detection

  • Antigen retrieval: May be necessary due to cross-linking during fixation

  • Dilution range: 1:50-1:100 for IHC applications with antibodies like ABIN1534977

• Special considerations:

  • HNRNPUL2's association with chromatin and nuclear structures requires adequate permeabilization

  • Overfixation may mask epitopes and reduce staining intensity

  • The dynamic nature of HNRNPUL2 localization means fixation timing is critical for capturing specific states

• Recommended controls:

  • Include positive control tissues/cells with known HNRNPUL2 expression

  • Human breast carcinoma tissue has been validated for HNRNPUL2 detection

  • Include blocking peptide controls to confirm specificity of staining patterns