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HNRNPU / Heterogeneous nuclear ribonucleoprotein U · IHC design guide
Design Immunohistochemistry for HNRNPU
Use widespread nuclear staining as the benchmark when assessing HNRNPU in paraffin sections (HPA tissue IHC). The catalog antibody has a recommended IHC concentration of 2–5 μg/ml for chromogenic detection (datasheet A03691-3).
Evidence assembled Oct 2026 · For research use; verify linked source records and product datasheet before use
HNRNPU Immunohistochemistry Experimental Design Guide
Expected localisation, validated protocols, controls and antibodies — the at-a-glance facts below, then the full design guide.
Must know before staining
| Expected localisation | Widespread nuclear tissue staining (HPA tissue IHC) | |
| Staining pattern | Nuclear staining across diverse tissue cell types (HPA tissue IHC) | |
| Antigen retrieval | EDTA pH 8.0 HIER, heat-mediated (datasheet A03691-3) | |
| Positive control | Adrenal gland+4 more · see all | |
| Negative control | None in HPA (detected in all 45 tissues); use no-primary + isotype controls |
Important caveats
Reasons your staining may differ from the expected pattern.
| Fixation | Keep fixation consistent across paraffin sections. (standard IHC practice; not target-specific) | |
| Caveat | Mitotic cells may show spindle or midbody signal (UniProt) | |
| Regulation | Low tissue specificity (HPA tissue RNA) | |
| Isoform / epitope | 2 isoforms; antibody epitope coverage is unspecified (UniProt) |
Section 1
Recommended HNRNPU IHC & IF Protocols
The catalog antibody’s IHC-P protocol is paired with one published paraffin-section protocol for HNRNPU (datasheet A03691-3; PMC9569266).
| Sample | Paraffin-embedded human breast cancer tissue; fixative not specified (datasheet A03691-3) |
| Fixation | Image fixative and duration unreported (datasheet A03691-3); verify before use. |
| Sectioning | 4–5 µm sections on charged slides (standard) |
| Deparaffinisation | Xylene, graded ethanol series to water (standard) |
| Antigen retrieval | Heat retrieval: EDTA pH 8.0 (datasheet A03691-3); 20 min, 95–100 °C (standard) |
| Peroxidase block | 3% H2O2, 10 min, room temperature (standard) |
| Blocking | 10% goat serum (datasheet A03691-3) |
| Primary antibody | Rabbit anti-HNRNPU, 2-5 μg/ml (datasheet A03691-3) |
| Primary incubation | Overnight at 4 °C (datasheet A03691-3) |
| Detection | HRP-conjugated secondary, DAB chromogen (datasheet A03691-3) |
| Counterstain | Hematoxylin, blue, dehydrate and mount (standard) |
| Expected result | HNRNPU-positive staining in glandular cells of adrenal gland (HPA tissue IHC: High). HPA tissue profile: Ubiquitous nuclear expression. No signal in the no-primary control. |
💡Decision noteStart with heat-mediated EDTA retrieval at pH 8.0 (datasheet A03691-3); the published protocol does not specify retrieval (PMC9569266).
Section 2
What Is the Expected HNRNPU Staining Pattern?
HNRNPU should appear mainly in nuclei across many cell types: HPA describes ubiquitous nuclear tissue staining with Supported reliability and medium agreement with RNA data (HPA: tissue IHC). High staining is reported in several cell populations, including appendix glandular cells and bone marrow hematopoietic cells (HPA: High in each). Its nuclear distribution fits a protein without a transmembrane segment (UniProt Q00839: localization and topology).
| Distinct nuclear chromogen in appendix glandular cells or bone marrow hematopoietic cells. | This fits reported High tissue staining and the predominant nuclear pattern (HPA: High in both cell types; HPA: ubiquitous nuclear expression). Compare nuclei with the counterstain when judging the compartment; color intensity alone does not establish specificity (general IHC practice). |
| Predominantly cytoplasmic staining in resting cells, with little nuclear signal. | Question this as an IHC result because the tissue profile is nuclear (HPA: ubiquitous nuclear expression). UniProt also lists cytoplasmic granules and mitotic spindle structures, so a discrete signal in the appropriate context needs separate assessment (UniProt Q00839: localization). |
| Strong staining in a cell population that seems unexpected for the sampled tissue. | Check cell identity and the tissue's HPA image before calling cross-reactivity: expression is widespread, and HPA reports High staining in diverse populations, including breast adipocytes and caudate glia (HPA: High in each; HPA: ubiquitous nuclear expression). Noncellular color or staining that follows endogenous detection activity can indicate an assay artefact (general IHC practice). |
| Haze across nuclei, cytoplasm, and blank areas of the section. | A diffuse pattern does not match the reported nuclear tissue profile (HPA: ubiquitous nuclear expression). Uneven reagent removal, excess detection signal, or endogenous activity are general IHC possibilities; evaluate a no-primary control and the counterstained morphology (general IHC practice). |
| No convincing nuclear signal in a known-positive control section. | A negative result conflicts with reported High staining if the control contains the specified cells, such as bronchial respiratory epithelium (HPA: High in respiratory epithelial cells). First confirm cell identity and that the control processed alongside the test section; then examine retrieval, antibody, and detection steps (general IHC practice). |
💡Expected HNRNPU appearanceCall positive when cell-associated nuclear chromogen is clear in the appropriate population, with strong staining possible in HPA-listed High cells (HPA: tissue IHC); broad cytoplasmic or noncellular color without matching nuclei is suspect (HPA: ubiquitous nuclear expression; general IHC practice).
| Tissue and cell selection | HPA calls tissue expression ubiquitous and RNA tissue specificity low, while naming individual High-staining populations (HPA: tissue IHC). Use a listed population as a positive reference; the supplied record provides no negative tissue standard. |
| Antibody evidence | HPA marks tissue IHC Supported for HPA041057, HPA058707, and CAB011532 (HPA: antibody validation). This supports comparison with the reported pattern but does not validate every antibody or every staining condition. |
| Compartment and cell cycle | The principal expectation is nuclear staining (HPA: tissue IHC; UniProt Q00839: interphase nucleus). UniProt also places HNRNPU at mitotic spindle structures and the midbody, so assess a localized mitotic signal against cell morphology before rejecting it (UniProt Q00839: localization). |
| Isoforms and epitope coverage | UniProt lists two isoforms and a chain spanning residues 2–825 (UniProt Q00839: isoforms and processing). The supplied evidence gives no antibody epitope, so it cannot establish whether an antibody detects both isoforms or whether a particular region survives processing. |
| Retrieval and detection | The supplied HPA and UniProt records do not report HNRNPU-specific fixation sensitivity or retrieval conditions. If a control fails, review the section's retrieval and detection workflow as general IHC practice; do not infer a target-specific fixation effect from the HPA pattern. |
| IF/ICC Q&A: Where should fluorescence appear? | Primarily in the nucleoplasm (HPA: supported ICC-IF main location). This is a localization reference for the separate IF/ICC guide, not an IHC protocol choice; HPA reports ICC Enhanced for HPA058707 (HPA: antibody validation). |
| Situation | Likely cause | Next action |
|---|---|---|
| Positive-control nuclei are unstained. | The control may lack its expected cell population, or retrieval, primary antibody, or chromogenic detection may have failed (HPA: High in listed positive cells; general IHC practice). | Verify the listed cells on the section and repeat with a concurrently processed positive control; check the recorded retrieval and detection steps (general IHC practice). |
| Cytoplasm dominates while interphase nuclei remain pale. | This conflicts with the principal tissue pattern (HPA: ubiquitous nuclear expression; UniProt Q00839: interphase nucleus). A diffuse cytoplasmic deposit may reflect nonspecific assay signal (general IHC practice). | Compare with a no-primary control, examine the counterstain, and reassess antibody concentration and detection conditions (general IHC practice). |
| Color appears on vessels, damaged areas, or spaces without intact cells. | Distribution outside intact nuclei is inconsistent with the reported tissue pattern (HPA: ubiquitous nuclear expression). Endogenous detection activity or deposited reagent may contribute (general IHC practice). | Inspect a no-primary control and apply the detection system's appropriate endogenous-activity block; score only intact, identifiable cells (general IHC practice). |
| Nearly every structure is brown, obscuring cell boundaries. | HNRNPU is widely expressed, but indiscriminate background cannot be interpreted as nuclear positivity (HPA: ubiquitous nuclear expression; general IHC practice). | Use counterstained morphology and a no-primary control to distinguish nuclei from background; review blocking, washes, and detection exposure (general IHC practice). |
| A suspected positive cell population shows weak or variable nuclei. | HPA's High designation describes observed staining in specified cells, while overall tissue IHC reliability is Supported with medium agreement with RNA data (HPA: tissue IHC). Section quality or assay variation may also matter (general IHC practice). | Confirm the cell population, compare an HPA-listed positive control stained in the same run, and score the visible nuclear pattern rather than assigning an absolute cutoff (HPA: tissue IHC; general IHC practice). |
| A focal spindle-like signal appears in dividing cells. | UniProt reports HNRNPU on mitotic spindle microtubules and at the midbody, depending on mitotic stage (UniProt Q00839: localization). | Check mitotic morphology and whether neighboring interphase cells show the expected nuclear pattern; avoid treating an isolated spindle-like deposit as sufficient IHC validation (HPA: ubiquitous nuclear expression; general IHC practice). |
Experiment evidence
IHC & IF images showing HNRNPU staining
A03691-3 · IHCIHC analysis of hnRNP U/p120/HNRNPU using anti-hnRNP U/p120/HNRNPU antibody (A03691-3). hnRNP U/p120/HNRNPU was detected in a paraffin-embed
A03691-3 · IHCIHC analysis of hnRNP U/p120/HNRNPU using anti-hnRNP U/p120/HNRNPU antibody (A03691-3). hnRNP U/p120/HNRNPU was detected in a paraffin-embed
A03691-3 · IFIF analysis of hnRNP U/p120/HNRNPU using anti-hnRNP U/p120/HNRNPU antibody (A03691-3). hnRNP U/p120/HNRNPU was detected in an immunocytochem
HPA · Cerebral cortexHuman Protein Atlas IHC, Cerebral cortex. Source: https://www.proteinatlas.org/ENSG00000153187-HNRNPU/tissue/cerebral+cortex#imid_16881915
HPA · ColonHuman Protein Atlas IHC, Colon. Source: https://www.proteinatlas.org/ENSG00000153187-HNRNPU/tissue/colon#imid_16881849
HPA · LiverHuman Protein Atlas IHC, Liver. Source: https://www.proteinatlas.org/ENSG00000153187-HNRNPU/tissue/liver#imid_16881842
HPA · KidneyHuman Protein Atlas IHC, Kidney. Source: https://www.proteinatlas.org/ENSG00000153187-HNRNPU/tissue/kidney#imid_16881843
HPA · ICC-IF HEK293Human Protein Atlas immunofluorescence, HEK293, antibody HPA058707; green = HNRNPU, blue = nucleus, red = microtubules.
HPA · ICC-IF HEK293Human Protein Atlas immunofluorescence, HEK293, antibody HPA058707; green = HNRNPU, blue = nucleus, red = microtubules.
← swipe / scroll for more images →
Real IHC / IF data behind the staining-pattern expectations in this section.
Sample controls for HNRNPU IHC & IF
🧪Run breast first and score adipocytes, which show High HNRNPU staining (HPA: High in breast adipocytes). HPA detects HNRNPU in all 45 scored tissues, so there is no supported negative tissue or reliably negative cell population on the positive slide; use no-primary and isotype controls to define background, including any apparent staining outside nuclei (HPA: detected in all 45 scored tissues; HPA: nucleoplasm supported).
Positive control tissue: Adrenal gland (Glandular cells, HPA High)
Negative control tissue: None in HPA: HNRNPU is detected in all 45 scored tissues. Use a no-primary (secondary-only) and an isotype control instead.
ICC-IF cell lines (HPA subcellular resource): HPA ICC-IF images show HNRNPU in HEK293, Hep-G2, U2OS, U2OS, siRNA 1 (10x), U2OS, siRNA 1 (40x), U2OS, scrambled (10x), U2OS, scrambled (40x), with annotated localisation: Nucleoplasm (supported) (HPA subcellular).
Technical controls: Run a secondary-only section with no primary antibody, a section with host- and isotype-matched control IgG, and HNRNPU knockout material if available to assess specificity (catalog caption: rabbit primary antibody; standard IHC controls). Quench endogenous peroxidase before HRP–DAB detection and check adipose-associated autofluorescence if examining breast tissue by IF (catalog caption: HRP–DAB detection; standard IHC/IF practice).
⚠️Feasibility: No target-specific fixation window or fixation effect is reported in the supplied evidence, and the selected A03691-3 breast cancer paraffin-section caption leaves the fixative unreported (selected SKU caption: fixative not stated). That caption demonstrates staining after heat retrieval in EDTA at pH 8.0, but does not establish that retrieval is required for every specimen (selected SKU caption: EDTA heat retrieval). Frozen-section or IF preparation cannot be judged easier from this evidence; adipose autofluorescence can complicate IF assessment in breast tissue (standard IF practice).
HPA tissue IHC evidence for HNRNPU
Comprehensive Human Protein Atlas IHC scoring per tissue (reliability: Supported — Medium consistency between antibody staining and RNA expression data.). Rows are taken directly from the HPA tissue chart — click any row's HPA link to view the source.
Positive expression · recommended positive controls
| Tissue | Cell type | Level | Evidence | Source |
|---|---|---|---|---|
| Adrenal gland | Glandular cells | High | Protein (IHC) | HPA → |
| Appendix | Glandular cells | High | Protein (IHC) | HPA → |
| Bone marrow | Hematopoietic cells | High | Protein (IHC) | HPA → |
| Breast | Adipocytes | High | Protein (IHC) | HPA → |
| Bronchus | Respiratory epithelial cells | High | Protein (IHC) | HPA → |
Undetected expression · recommended negative controls
| Tissue | Cell type | Level | Evidence | Source |
|---|---|---|---|---|
| None in HPA: HNRNPU is detected in all 45 scored tissues. Use a no-primary (secondary-only) and an isotype control instead. | ||||
Section 3
Advanced HNRNPU IHC Tips
Troubleshoot HNRNPU staining in paraffin sections by checking retrieval, nuclear localisation, background and scoring against the catalog antibody’s tissue IHC evidence.
How should I retrieve HNRNPU when nuclear staining is weak?
Start with heat-mediated retrieval in EDTA at pH 8.0 (datasheet A03691-3). The catalog antibody produced staining in a paraffin section of human breast cancer tissue with this retrieval, followed by 2 μg/ml primary antibody overnight at 4°C (datasheet A03691-3). If nuclei remain weak, compare a longer heat exposure with the established condition on adjacent sections, keeping detection and imaging constant (standard IHC practice). Check tissue preservation and an on-slide positive control before interpreting weak staining as low HNRNPU expression; the expected pattern is predominantly nuclear (HPA: ubiquitous nuclear expression).
Could fixation explain uneven HNRNPU staining across paraffin sections?
Target-specific fixation sensitivity is unknown because the selected tissue IHC caption does not report a fixative (datasheet A03691-3). Record the fixative, fixation duration, tissue thickness and processing history for each specimen before comparing staining intensity (standard IHC practice). Compare adjacent sections using the same EDTA pH 8.0 retrieval, 2 μg/ml primary concentration and overnight incubation at 4°C used in the selected example (datasheet A03691-3). If staining varies with specimen handling, optimise processing with matched controls and assess nuclear morphology; that association alone does not establish an HNRNPU-specific fixation effect (standard IHC practice).
How should I assess HNRNPU staining outside nuclei?
Expect widespread nuclear staining in tissue sections, and assess each stained structure against the hematoxylin-defined nucleus (HPA: ubiquitous nuclear expression; standard IHC practice). Nucleoplasmic localisation is supported by cell imaging, while UniProt also records nuclear matrix and speckle locations (HPA: nucleoplasm supported; UniProt Q00839 subcellular localisation). Cytoplasmic granules and mitotic spindle structures are reported contexts, so focal extranuclear signal deserves cell-cycle and morphology review rather than automatic rejection (UniProt Q00839 subcellular localisation). For an interphase cell with diffuse cytoplasmic DAB and little nuclear staining, repeat with a concentration series around 2 μg/ml and inspect background controls (datasheet A03691-3; standard IHC practice).
Can this IHC stain distinguish HNRNPU isoforms or a modified epitope?
Do not assign an isoform from this chromogenic stain: the supplied record lists 2 HNRNPU isoforms, but the selected caption gives no antibody epitope or isoform selectivity (UniProt Q00839 isoforms; datasheet A03691-3). HNRNPU contains a SAP domain at residues 8–42 and a B30.2/SPRY domain at 267–464, which cannot identify the bound epitope without antibody mapping (UniProt Q00839 domains; standard IHC interpretation). The record also lists Ser-59 phosphorylation during mitosis, but ordinary total-protein IHC does not establish modification-specific detection (UniProt Q00839 modified residues; standard IHC interpretation). Confirm isoform or phosphosite claims with an independently validated reagent and appropriate controls (standard IHC practice).
How can I adapt the HNRNPU readout to multiplex IF?
Use the IF/ICC guide to validate this application separately; the selected caption documents chromogenic staining of a paraffin section, not an IF result (datasheet A03691-3). Pair HNRNPU with a marker for the expected cell population and a nuclear counterstain so colocalisation can be scored within identified cells (HPA: cell-specific tissue staining; standard IF practice). Choose fluorophores after checking tissue autofluorescence in unstained sections, favouring channels with clear signal separation (standard IF practice). Because HNRNPU has no transmembrane segment and the principal expected signal is nucleoplasmic, permeabilise for access to an intracellular epitope and titrate conditions against nuclear morphology (UniProt Q00839 topology; HPA: nucleoplasm supported; standard IF practice).
What causes diffuse brown staining around HNRNPU-positive nuclei?
First compare the section with a no-primary control to separate antibody-dependent staining from detection background (standard IHC practice). The selected example used 10% goat serum blocking, a peroxidase-conjugated secondary and DAB development; these describe the tested workflow, not proof that every brown deposit is HNRNPU (datasheet A03691-3). Quench endogenous peroxidase and review DAB development time, washes and primary-antibody concentration if diffuse staining persists (standard IHC practice). Interpret a clean, predominantly nuclear pattern against the expected ubiquitous nuclear expression, and inspect tissue edges or damaged areas separately (HPA: ubiquitous nuclear expression; standard IHC practice).
How should I quantify variable nuclear HNRNPU staining? ⚠ ANSWER MARKED FOR VERIFICATION
Define the cell population and analyse comparable, viable regions before measuring chromogenic signal (standard IHC practice). Score nuclear intensity and the percentage of positive nuclei, then report a nuclear H-score from 0–300 or the percentage positive using fixed thresholds across samples (standard IHC practice). Normalise counts to the number of evaluable nuclei, or report positive-cell density per mm² when cell density itself is relevant; keep compartment and denominator explicit (standard IHC practice). Avoid treating whole-section brown area as HNRNPU abundance because the expected tissue profile is ubiquitous nuclear expression and cell composition can change the aggregate result (HPA: ubiquitous nuclear expression; standard IHC interpretation).
How do I distinguish genuine HNRNPU signal from artefact?
Look for nuclear DAB in intact cells across the section, consistent with the reported ubiquitous nuclear tissue pattern (HPA: ubiquitous nuclear expression; standard IHC practice). A stained cytoplasmic rim without a corresponding nucleus, an edge-only gradient or signal concentrated in necrotic areas warrants review of morphology and controls before calling positivity (standard IHC practice). Check a no-primary control and peroxidase block when brown deposits could reflect endogenous enzyme activity rather than antibody binding (standard IHC practice). Interpret focal spindle-associated staining cautiously in mitotic cells: UniProt reports that localisation, but the selected chromogenic tissue caption does not validate a spindle-specific IHC readout (UniProt Q00839 subcellular localisation; datasheet A03691-3).
Boster reagents
Best HNRNPU / Heterogeneous nuclear ribonucleoprotein U IHC Antibodies
A03691-3 has IHC images from human paraffin sections and IF images from SiHa cells and human, mouse and rat samples (catalog image captions). M03691 lists IHC and IF/ICC applications (catalog applications).
Real IHC data
Anti-hnRNP U/p120/HNRNPU Antibody ®
Cat # A03691-3
A03691-3 has IHC images from paraffin sections of human breast, gastric, colorectal and esophageal cancers, plus IF images from SiHa cells, human breast cancer sections, and mouse and rat brain sections (catalog image captions). M03691 lists IHC and IF/ICC applications and human, mouse and rat reactivity, but has no IHC or IF image captions in the payload (catalog applications; catalog reactivity; catalog image captions).
Which to pick: For tissue IHC, choose A03691-3: its own captions document staining in human paraffin sections with EDTA retrieval at pH 8.0 and 2 μg/ml primary antibody; the fixative is unreported (A03691-3 IHC image captions). For IF/ICC, A03691-3 has image examples in SiHa cells and human, mouse and rat sections at 5 μg/ml (A03691-3 IF image captions). M03691 is a rabbit monoclonal, clone AEDD-8, that lists IHC, IF/ICC and human, mouse and rat reactivity, but A03691-3 provides the documented cross-species IF examples (M03691 catalog entry; A03691-3 IF image captions).
Each figure is that product's own IHC / IF validation image from its datasheet.
References
- UniProt Consortium. UniProt entry Q00839 (HNRPU_HUMAN, Heterogeneous nuclear ribonucleoprotein U).
- Human Protein Atlas. HNRNPU tissue IHC expression (reliability: Supported).
- Human Protein Atlas. HNRNPU subcellular location (ICC-IF): Localized to the nucleoplasm..
- Human Protein Atlas. HNRNPU antibody validation summary (3 antibodies).
- Astrocytic heterogeneous nuclear ribonucleoprotein U is involved in scar formation after spinal cord injury. Journal of neuroinflammation 2025 — PMC11786496.
- High expression of RUVBL1 and HNRNPU is associated with poor overall survival in stage I and II non-small cell lung cancer patients. Discover oncology 2022 — PMC9569266.
- Identification of therapeutic targets and prognostic biomarkers from the hnRNP family in invasive breast carcinoma. Aging 2021 — PMC7906176.
- FAM171B stabilizes vimentin and enhances CCL2-mediated TAM infiltration to promote bladder cancer progression. Journal of experimental & clinical cancer research : CR 2023 — PMC10621219.
- PubMed PMID:1628625 — UniProt-cited evidence.
- PubMed PMID:7509195 — UniProt-cited evidence.
- PubMed PMID:16710414 — UniProt-cited evidence.
Immunohistochemistry protocol sheet for HNRNPU (Heterogeneous nuclear ribonucleoprotein U). Expected localisation Widespread nuclear tissue staining (HPA tissue IHC). Antigen retrieval: EDTA pH 8.0 HIER, heat-mediated (datasheet A03691-3). Validated IHC antibody: A03691-3 at 2-5 μg/ml (the product's own IHC validation image is shown). Controls (HPA): positive Adrenal gland (Glandular cells); negative None in HPA (detected in all 45 tissues); use no-primary + isotype controls. IHC-P workflow on paraffin sections; fixative unspecified. Protocol steps: 1. Sample: Paraffin-embedded human breast cancer tissue; fixative not specified (datasheet A03691-3); 2. Fixation: Image fixative and duration unreported (datasheet A03691-3); verify before use.; 3. Sectioning: 4–5 µm sections on charged slides (standard); 4. Deparaffinisation: Xylene, graded ethanol series to water (standard); 5. Antigen retrieval: Heat retrieval: EDTA pH 8.0 (datasheet A03691-3); 20 min, 95–100 °C (standard); 6. Peroxidase block: 3% H2O2, 10 min , room temperature (standard); 7. Blocking: 10% goat serum (datasheet A03691-3); 8. Primary antibody: Rabbit anti-HNRNPU, 2-5 μg/ml (datasheet A03691-3); 9. Primary incubation: Overnight at 4 °C (datasheet A03691-3). Watch for: Fixation: Keep fixation consistent across paraffin sections. (standard IHC practice; not target-specific); Caveat: Mitotic cells may show spindle or midbody signal (UniProt); Isoform / epitope: 2 isoforms; antibody epitope coverage is unspecified (UniProt); Regulation: Low tissue specificity (HPA tissue RNA). Evidence: UniProt Q00839, HPA tissue IHC · Supported, HPA ICC-IF · nucleoplasm., Datasheet A03691-3, PMC9569266. QR code links to https://www.bosterbio.com/bosterbio-gene-info-cards/HNRNPU/immunohistochemistry-ihc-guide.