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FUS / RNA-binding protein FUS · IHC design guide
Design Immunohistochemistry for FUS
Plan chromogenic FUS IHC in paraffin sections, from fixation and antigen retrieval through nuclear scoring. Expect widespread nuclear staining across tissue cell types (HPA tissue IHC).
Evidence assembled Oct 2026 · For research use; verify linked source records and product datasheet before use
FUS 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 | Nuclear staining (HPA tissue IHC) | |
| Staining pattern | Widespread nuclear staining across cell types (HPA tissue IHC) | |
| Antigen retrieval | EDTA pH 8.0 HIER, heat-mediated (datasheet A00771-3) | |
| Positive control | Adipose tissue+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 conditions consistent across sections (standard IHC practice; not target-specific) | |
| Caveat | Widespread nuclear signal can complicate cell-specific scoring (HPA tissue IHC) | |
| Regulation | Low tissue specificity (HPA tissue RNA) | |
| Isoform / epitope | Long and Short isoforms; check epitope coverage (UniProt) |
Section 1
Recommended FUS IHC & IF Protocols
The catalog antibody protocol is paired with published FUS IHC methods for post-mortem CNS tissue and paraffin sections (PMC12407188; PMC2864899; PMC3319073).
| Sample | Paraffin-embedded human rectal cancer tissue; fixative not specified (datasheet A00771-3) |
| Fixation | Image fixative and duration unreported (datasheet A00771-3); 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 A00771-3); 20 min, 95–100 °C (standard) |
| Peroxidase block | 3% H2O2, 10 min, room temperature (standard) |
| Blocking | 10% goat serum (datasheet A00771-3) |
| Primary antibody | Rabbit anti-FUS, 2 μg/ml (datasheet A00771-3) |
| Primary incubation | Overnight at 4 °C (datasheet A00771-3) |
| Detection | HRP-conjugated secondary, DAB chromogen (datasheet A00771-3) |
| Counterstain | Hematoxylin, blue, dehydrate and mount (standard) |
| Expected result | FUS-positive staining in adipocytes of adipose tissue (HPA tissue IHC: High). HPA tissue profile: Ubiquitous nuclear expression. No signal in the no-primary control. |
💡Decision noteStart with heat-mediated EDTA pH 8.0 retrieval for the catalog antibody (datasheet: A00771-3). Published methods also used pressure cooking or microwave retrieval (PMC2864899; PMC3319073).
Section 2
What Is the Expected FUS Staining Pattern?
FUS should stain predominantly in nuclei across many cell types in paraffin sections: HPA describes ubiquitous nuclear expression with supported tissue IHC reliability and low tissue RNA specificity (HPA: tissue IHC). UniProt places FUS in the nucleus, where it can appear punctate and is excluded from nucleoli (UniProt P35637: subcellular location). FUS has no transmembrane segment, so membrane staining is unexpected (UniProt P35637: topology).
| Nuclear chromogen in adipocytes, marrow hematopoietic cells, or brain glial cells. | This matches reported high staining in those cells (HPA: tissue IHC). Assess the fraction of stained nuclei and their intensity against an appropriate reference section; HPA's 'High' category does not set a numerical scoring cutoff. |
| Predominantly membranous or cytoplasmic staining, with little nuclear signal. | The compartment conflicts with HPA's ubiquitous nuclear IHC profile and UniProt's nuclear location and lack of a transmembrane segment (HPA: tissue IHC; UniProt P35637: subcellular location, topology). Check morphology and detection controls before calling it FUS. |
| Strong staining in a cell population absent from the matched reference pattern. | Cross-reactivity or endogenous detection activity is possible; verify with a reagent control and a second validated antibody. FUS is broadly expressed, and HPA lists no negative tissues, so an unfamiliar positive cell type alone cannot establish a false positive (HPA: tissue IHC, antibodies). |
| Hazy chromogen across nuclei, cytoplasm, and surrounding tissue. | Poor compartment definition prevents confident scoring against the expected nuclear pattern (HPA: tissue IHC). General IHC practice: inspect reagent controls and review blocking, washes, antibody concentration, and detection conditions to locate background. |
| No nuclear signal in a known-positive reference section. | An absent signal conflicts with high staining reported in selected reference cells, such as marrow hematopoietic cells or cerebellar granular-layer cells (HPA: tissue IHC). First check reference morphology and run controls; general IHC practice is to review retrieval, antibody dilution, and detection. |
💡Expected FUS appearanceCall a result positive when chromogen is predominantly nuclear in the relevant cells, with clear high staining in an HPA-listed high population; a dominant membrane or cytoplasmic pattern is suspect (HPA: tissue IHC; UniProt P35637: subcellular location, topology).
| Cellular location and topology | HPA reports ubiquitous nuclear IHC staining, while UniProt describes punctate nuclear FUS that excludes nucleoli and has no transmembrane segment (HPA: tissue IHC; UniProt P35637: subcellular location, topology). Use nuclear location as the primary interpretation criterion; fine puncta may be difficult to resolve with chromogenic IHC. |
| Tissue and cell context | HPA reports high staining in adipocytes, adrenal glandular cells, bronchial respiratory epithelial cells, caudate glial cells, and other listed populations (HPA: tissue IHC). Its positive examples guide reference selection; the supplied HPA record lists no negative tissue or cell population, so do not use one as a required negative control. |
| Antibody validation | HPA lists three antibodies with supported IHC status: HPA008784, CAB033036, and CAB058691 (HPA: antibodies). That supports checking the nuclear pattern with an independently validated reagent when a result is disputed. The supplied validation summary does not establish that every catalog antibody recognizes the same epitope. |
| Isoforms and sequence features | UniProt lists long and short FUS isoforms, one protein chain spanning residues 1–526, and an RNA-recognition motif at residues 285–371 (UniProt P35637: isoforms, processing, domains). Without an antibody epitope in the supplied record, these features do not predict isoform-specific staining or justify an antigen-retrieval setting. |
| IF/ICC Q&A: where should signal appear? | In IF/ICC, expect nucleoplasmic FUS; HPA supports that location and lists U2OS, A-431, and U-251MG image examples (HPA: subcellular ICC-IF). UniProt additionally describes punctate nuclear distribution with nucleolar exclusion (UniProt P35637: subcellular location). Interpret that localization in the separate IF/ICC guide. |
| Situation | Likely cause | Next action |
|---|---|---|
| A reference section shows weak or absent nuclear chromogen. | The result is inconsistent with HPA's high staining in the chosen listed cell population (HPA: tissue IHC); the assay step responsible is not identifiable from that observation alone. | Confirm that the reference contains the expected cells. As general IHC checks, review retrieval, antibody dilution, detection reagents, and a working positive control. |
| Cytoplasmic or membrane signal dominates. | That distribution conflicts with the reported nuclear pattern and absence of a transmembrane segment (HPA: tissue IHC; UniProt P35637: subcellular location, topology). | Compare the stained section with morphology and a reagent control; repeat with an independently IHC-supported antibody if the compartment discrepancy persists (HPA: antibodies). |
| Broad staining obscures nuclear boundaries. | The signal cannot be assigned reliably to the expected nuclear compartment (HPA: tissue IHC). General IHC causes to investigate include concentrated antibody or nonspecific detection background. | Use reagent controls to locate the background; review antibody dilution, blocking, washes, and detection conditions as general IHC practice. |
| An unexpected cell population stains strongly. | Cross-reactivity or endogenous detection activity may contribute, but HPA reports ubiquitous nuclear expression and supplies no negative population (HPA: tissue IHC). | Check whether staining remains nuclear, inspect a detection control, and compare with a second IHC-supported antibody (HPA: antibodies) before rejecting the cell population. |
| Two antibodies produce different staining patterns. | HPA supports IHC use for HPA008784, CAB033036, and CAB058691, but the supplied record gives no shared epitope or isoform coverage (HPA: antibodies; UniProt P35637: isoforms). | Compare the same reference tissue and nuclear compartment under controlled conditions; document each reagent's result without assigning the difference to a specific isoform. |
| A proposed retrieval change appears to restore signal. | The supplied HPA and UniProt records do not establish FUS-specific fixation sensitivity or an optimal retrieval condition. | Treat retrieval as a general IHC variable: compare sections with matched positive and reagent controls, then score nuclear localization against the HPA pattern (HPA: tissue IHC). |
Experiment evidence
IHC & IF images showing FUS staining
A00771-3 · IHCIHC analysis of TLS/FUS using anti-TLS/FUS antibody (A00771-3). TLS/FUS was detected in a paraffin-embedded section of human rectal cancer t
A00771-3 · IHCIHC analysis of TLS/FUS using anti-TLS/FUS antibody (A00771-3). TLS/FUS was detected in a paraffin-embedded section of mouse colon tissue. H
A00771-3 · IFIF analysis of TLS/FUS using anti-TLS/FUS antibody (A00771-3) and anti-Tubulin alpha antibody (M03989-2). TLS/FUS was detected in immunocyto
M00771-2 · IHCMouse brain was stained with anti-TLS/FUS rabbit antibody
M00771-2 · IHCRat brain was stained with anti-TLS/FUS rabbit antibody
HPA · Cerebral cortexHuman Protein Atlas IHC, Cerebral cortex. Source: https://www.proteinatlas.org/ENSG00000089280-FUS/tissue/cerebral+cortex#imid_15527459
HPA · ColonHuman Protein Atlas IHC, Colon. Source: https://www.proteinatlas.org/ENSG00000089280-FUS/tissue/colon#imid_15527393
HPA · LiverHuman Protein Atlas IHC, Liver. Source: https://www.proteinatlas.org/ENSG00000089280-FUS/tissue/liver#imid_15527378
HPA · KidneyHuman Protein Atlas IHC, Kidney. Source: https://www.proteinatlas.org/ENSG00000089280-FUS/tissue/kidney#imid_15527387
HPA · ICC-IF U2OSHuman Protein Atlas immunofluorescence, U2OS, antibody CAB033036; green = FUS, blue = nucleus, red = microtubules.
HPA · ICC-IF U2OSHuman Protein Atlas immunofluorescence, U2OS, antibody CAB033036; green = FUS, blue = nucleus, red = microtubules.
← swipe / scroll for more images →
Real IHC / IF data behind the staining-pattern expectations in this section.
Sample controls for FUS IHC & IF
🧪Run adipose tissue first and look for nuclear staining in adipocytes (HPA: High in adipocytes; UniProt P35637: nuclear localisation). HPA detects FUS in all 45 scored tissues, so there is no HPA negative tissue; use no-primary and isotype controls, and expect adipocyte lipid vacuoles and extracellular spaces to remain unstained rather than treating other nucleated cells as internal negatives (HPA: no negative rows; UniProt P35637: ubiquitous).
Positive control tissue: Adipose tissue (Adipocytes, HPA High)
Negative control tissue: None in HPA: FUS 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 FUS in U2OS, A-431, U-251MG, with annotated localisation: Nucleoplasm (supported) (HPA subcellular).
Technical controls: Include a no-primary, secondary-only slide and a concentration-matched rabbit IgG isotype control (selected IHC caption: rabbit primary and anti-rabbit secondary); use a FUS knockout specimen as a biological negative where available. Quench endogenous peroxidase before HRP/DAB detection and check lipid-rich adipose tissue for background (selected IHC caption: HRP/DAB; HPA: adipocytes).
⚠️Feasibility: A target-specific fixation window or fixation effect is unreported, and the selected A00771-3 paraffin-section caption does not state a fixative (selected IHC caption: fixative not stated). Heat-mediated retrieval in EDTA, pH 8.0 was used, but retrieval dependence is unreported (selected IHC caption: EDTA retrieval). The supplied evidence does not establish whether frozen sections or IF are easier; adipocyte lipid vacuoles can complicate nuclear scoring, so assess staining in intact nuclei (HPA: adipocytes; UniProt P35637: nuclear localisation).
HPA tissue IHC evidence for FUS
Comprehensive Human Protein Atlas IHC scoring per tissue (reliability: Supported — High 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 |
|---|---|---|---|---|
| Adipose tissue | Adipocytes | High | Protein (IHC) | HPA → |
| Adrenal gland | Glandular cells | High | Protein (IHC) | HPA → |
| Appendix | Endocrine cells | High | Protein (IHC) | HPA → |
| Bone marrow | Hematopoietic cells | High | Protein (IHC) | HPA → |
| Breast | Adipocytes | High | Protein (IHC) | HPA → |
Undetected expression · recommended negative controls
| Tissue | Cell type | Level | Evidence | Source |
|---|---|---|---|---|
| None in HPA: FUS is detected in all 45 scored tissues. Use a no-primary (secondary-only) and an isotype control instead. | ||||
Section 3
Advanced FUS IHC Tips
Troubleshoot FUS staining in paraffin section IHC by checking retrieval, nuclear localisation, epitope access, controls and scoring before interpreting changes in expression.
What retrieval should I start with for FUS in paraffin sections?
Start with heat mediated retrieval in EDTA at pH 8.0 for paraffin sections (datasheet A00771-3). The selected tissue image used this retrieval before overnight incubation at 4°C with 2 μg/mL primary antibody (datasheet A00771-3). Keep section thickness, heating and cooling consistent across comparison slides, and include a no primary control to assess detection background (standard IHC practice). If nuclear staining is weak, adjust heating duration on paired sections before considering another retrieval buffer as a fallback (standard IHC practice). Judge changes by nuclear signal and tissue preservation together, since FUS is principally nuclear (UniProt P35637; HPA: ubiquitous nuclear expression).
How can I troubleshoot fixation effects on FUS staining?
The selected image documents paraffin embedding but does not report a fixative, so target specific fixation sensitivity is unknown (datasheet A00771-3). Record the fixative and fixation interval for each specimen, then compare matched sections processed with the same retrieval and staining run (standard IHC practice). Poor nuclear detail, uneven staining or loss of tissue can indicate a preparation problem, but none establishes a FUS specific fixation effect (standard IHC practice). Use a well preserved reference section with the same processing history and the no primary control when assessing a weak result (standard IHC practice). Interpret the expected signal in nuclei, where FUS is reported to localise (UniProt P35637; HPA: ubiquitous nuclear expression).
Where should convincing FUS staining appear in tissue?
Expect predominantly nuclear staining: FUS has a punctate nuclear pattern and is excluded from nucleoli (UniProt P35637). Tissue IHC reports ubiquitous nuclear expression, with high staining in adipocytes, hematopoietic cells and glial cells among the listed examples (HPA: tissue IHC). Check whether signal follows intact nuclei across the section, using a nuclear counterstain to distinguish nucleoplasm from adjacent cytoplasm (HPA: nucleoplasm supported; standard IHC practice). A diffuse cytoplasmic DAB deposit alone does not match the reported baseline localisation and needs an independent control before biological interpretation (UniProt P35637; standard IHC practice). Compare cells within the same section under identical illumination and scoring criteria (standard IHC practice).
Can this stain distinguish FUS isoforms or modified epitopes?
FUS has Long and Short isoforms, but the supplied product evidence does not map this antibody's epitope or establish isoform discrimination (UniProt P35637; datasheet A00771-3). Its annotated RNA recognition motif spans residues 285–371, and the record includes phosphorylation and arginine methylation sites (UniProt P35637). Those annotations alone cannot show that retrieval or staining preferentially detects either isoform or modification state (UniProt P35637; standard IHC interpretation). If an isoform or modification claim matters, obtain epitope mapping and test an independently validated reagent alongside the catalog antibody on matched sections (standard IHC practice). Report the result as FUS immunoreactivity until that specificity is established (standard IHC interpretation).
How should I check FUS localisation by multiplex IF?
For the separate IF/ICC application, pair FUS with a marker identifying the cell population under study and a nuclear stain, then assess overlap within individual nuclei (HPA: nucleoplasm supported; standard IF practice). Choose fluorophores after checking unstained tissue autofluorescence, and include single stain controls when channels will be compared (standard IF practice). FUS has no transmembrane segment and is reported in the nucleoplasm, so optimise permeabilisation for access to an intracellular nuclear epitope (UniProt P35637; HPA: nucleoplasm supported; standard IF practice). Titrate permeabilisation on matched samples to preserve morphology and avoid apparent redistribution caused by harsh processing (standard IF practice). Use the IF/ICC guide for application specific conditions; the selected caption documents tissue IHC (datasheet A00771-3).
How do I reduce diffuse or misleading DAB background?
The selected paraffin section image used 10% goat serum blocking, 2 μg/mL primary antibody overnight at 4°C, and DAB development after peroxidase detection (datasheet A00771-3). Start by comparing a no primary slide and a matched stained slide to locate secondary reagent or chromogen background (standard IHC practice). Include a peroxidase blocking step where appropriate, and inspect pigment or tissue damage before calling brown deposits positive (standard IHC practice). Titrate primary antibody and development time together only on matched sections, retaining nuclear detail as the decision criterion (standard IHC practice; HPA: ubiquitous nuclear expression). Background outside intact nuclei is less persuasive as FUS signal because its supported location is nucleoplasmic (HPA: nucleoplasm supported).
How should I score FUS staining across specimens? ⚠ ANSWER MARKED FOR VERIFICATION
Define the tissue compartment and eligible intact cells before scoring, then report the percentage of positive nuclei with a prespecified intensity scale or a nuclear H-score (standard IHC practice; HPA: ubiquitous nuclear expression). If measuring cell abundance, report positive nuclei per mm² of evaluable tissue and state how that area was selected (standard IHC practice). Normalise nuclear positivity to the total eligible nuclei in the same compartment, rather than to all tissue area when cellularity varies (standard IHC practice). Keep retrieval, exposure to chromogen and scoring thresholds consistent across specimens (standard IHC practice). Record excluded necrotic or damaged regions and assess observer agreement when comparing groups (standard IHC practice).
When is an unusual FUS staining pattern credible?
A credible baseline result follows intact nucleoplasm, with possible puncta and relative nucleolar exclusion (UniProt P35637; HPA: nucleoplasm supported). High nuclear expression is reported across multiple cell populations, so cell identity and the fraction of stained nuclei matter more than a single dark field (HPA: tissue IHC; standard IHC interpretation). Treat staining confined to section edges, necrotic zones or visibly damaged cells as suspect until it persists in well preserved regions (standard IHC practice). Check a no primary control and the peroxidase block when brown deposits appear outside nuclei or track endogenous enzyme activity (standard IHC practice). An apparent cytoplasmic shift warrants independent antibody or orthogonal evidence before assigning biological meaning (UniProt P35637; standard IHC interpretation).
Boster reagents
Best FUS / RNA-binding protein FUS IHC Antibodies
IHC images show human rectal cancer and mouse and rat colon paraffin sections, plus mouse and rat brain; an IF/ICC image shows A431 cells (catalog image captions).
Real IHC data
Anti-TLS/FUS Antibody ®
Cat # A00771-3
Real IHC data
Anti-TLS/FUS Rabbit Monoclonal Antibody
Cat # M00771-2
A00771-3 has IHC images from human rectal cancer and mouse and rat colon paraffin sections, plus an IF/ICC image from A431 cells (A00771-3 image captions). M00771-2 has mouse and rat brain IHC images and lists human, mouse, and rat reactivity for IHC and IF (M00771-2 image captions; catalog).
Which to pick: Choose A00771-3 for paraffin-section IHC when a matching tissue image matters; its captions show human rectal cancer and mouse and rat colon, but do not report the fixative (A00771-3 IHC captions). For IF/ICC, A00771-3 has an A431-cell image, while M00771-2 lists IF without an IF image (A00771-3 IF caption; M00771-2 catalog). For cross-species IHC, A00771-3 has images from all three listed species; M00771-2 is a rabbit monoclonal with mouse and rat brain images and listed human reactivity (A00771-3 IHC captions; M00771-2 IHC captions and catalog).
Each figure is that product's own IHC / IF validation image from its datasheet.
References
- UniProt Consortium. UniProt entry P35637 (FUS_HUMAN, RNA-binding protein FUS).
- Human Protein Atlas. FUS tissue IHC expression (reliability: Supported).
- Human Protein Atlas. FUS subcellular location (ICC-IF): Localized to the nucleoplasm..
- Human Protein Atlas. FUS antibody validation summary (3 antibodies).
- Antisense oligonucleotide jacifusen for FUS-ALS: an investigator-initiated, multicentre, open-label case series. Lancet (London, England) 2025 — PMC12407188.
- Abundant FUS-immunoreactive pathology in neuronal intermediate filament inclusion disease. Acta neuropathologica 2009 — PMC2864784.
- Frequency of ubiquitin and FUS-positive, TDP-43-negative frontotemporal lobar degeneration. Journal of neurology 2010 — PMC2864899.
- Pathological heterogeneity in amyotrophic lateral sclerosis with FUS mutations: two distinct patterns correlating with disease severity and mutation. Acta neuropathologica 2011 — PMC3319073.
- PubMed PMID:8510758 — UniProt-cited evidence.
- PubMed PMID:7503811 — UniProt-cited evidence.
- PubMed PMID:9795213 — UniProt-cited evidence.
Immunohistochemistry protocol sheet for FUS (RNA-binding protein FUS). Expected localisation Nuclear staining (HPA tissue IHC). Antigen retrieval: EDTA pH 8.0 HIER, heat-mediated (datasheet A00771-3). Validated IHC antibody: A00771-3 at 2 μg/ml (the product's own IHC validation image is shown). Controls (HPA): positive Adipose tissue (Adipocytes); 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 rectal cancer tissue; fixative not specified (datasheet A00771-3); 2. Fixation: Image fixative and duration unreported (datasheet A00771-3); 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 A00771-3); 20 min, 95–100 °C (standard); 6. Peroxidase block: 3% H2O2, 10 min , room temperature (standard); 7. Blocking: 10% goat serum (datasheet A00771-3); 8. Primary antibody: Rabbit anti-FUS, 2 μg/ml (datasheet A00771-3); 9. Primary incubation: Overnight at 4 °C (datasheet A00771-3). Watch for: Fixation: Keep fixation conditions consistent across sections (standard IHC practice; not target-specific); Caveat: Widespread nuclear signal can complicate cell-specific scoring (HPA tissue IHC); Isoform / epitope: Long and Short isoforms; check epitope coverage (UniProt); Regulation: Low tissue specificity (HPA tissue RNA). Evidence: UniProt P35637, HPA tissue IHC · Supported, HPA ICC-IF · nucleoplasm., Datasheet A00771-3, PMC12407188, PMC2864899. QR code links to https://www.bosterbio.com/bosterbio-gene-info-cards/FUS/immunohistochemistry-ihc-guide.