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PARN / Poly(A)-specific ribonuclease PARN · IHC design guide
Design Immunohistochemistry for PARN
Plan PARN staining in paraffin sections using its cytoplasmic and nuclear tissue pattern (HPA tissue IHC). This guide covers fixation, antibody selection, chromogenic detection and interpretation of staining.
Evidence assembled Oct 2026 · For research use; verify linked source records and product datasheet before use
PARN 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 | Cytoplasmic and nuclear in most tissues (HPA tissue IHC) | |
| Staining pattern | Most tissues show cytoplasmic and nuclear staining (HPA tissue IHC) | |
| Antigen retrieval | Citrate pH 6 HIER, heat-mediated (datasheet A01501-2) | |
| Positive control | Adrenal gland+4 more · see all | |
| Negative control | None in HPA (detected in all 44 tissues); use no-primary + isotype controls |
Important caveats
Reasons your staining may differ from the expected pattern.
| Fixation | Keep fixation consistent across sections (standard IHC practice; not target-specific) | |
| Caveat | Staining has medium consistency with RNA expression (HPA tissue IHC) | |
| Regulation | Low tissue specificity (HPA tissue RNA) | |
| Isoform / epitope | 4 isoforms; check epitope coverage (UniProt) |
Section 1
Recommended PARN IHC & IF Protocols
The catalog antibody protocol uses citrate pH 6 retrieval (datasheet A01501-2); the published PARN IHC protocol uses EDTA pH 8 (PMC10473923).
| Sample | Paraffin-embedded human mammary cancer tissue; fixative not specified (datasheet A01501-2) |
| Fixation | Image fixative and duration unreported (datasheet A01501-2); verify before use. |
| Sectioning | 4–5 µm sections on charged slides (standard) |
| Deparaffinisation | Xylene, graded ethanol series to water (standard) |
| Antigen retrieval | Heat retrieval: Citrate pH 6, 20 min (datasheet A01501-2) |
| Peroxidase block | 3% H2O2, 10 min, room temperature (standard) |
| Blocking | 10% goat serum (datasheet A01501-2) |
| Primary antibody | Rabbit anti-PARN, 0.5-1μg/ml (datasheet A01501-2) |
| Primary incubation | Overnight at 4 °C (datasheet A01501-2) |
| Detection | Streptavidin-biotin complex (SABC), DAB chromogen (datasheet A01501-2) |
| Counterstain | Hematoxylin, blue, dehydrate and mount (standard) |
| Expected result | PARN-positive staining in glandular cells of adrenal gland (HPA tissue IHC: High). HPA tissue profile: Cytoplasmic and nuclear expression in most tissues. No signal in the no-primary control. |
💡Decision noteStart with citrate pH 6 retrieval for the catalog antibody (datasheet A01501-2). For the published tissue protocol, use EDTA pH 8 (PMC10473923).
Section 2
What Is the Expected PARN Staining Pattern?
PARN should show cytoplasmic and nuclear staining in many tissues, with high staining reported in selected glandular, respiratory epithelial, adipocyte, and neural cell populations (HPA: tissue IHC). Some nuclear PARN is nucleolar (UniProt O95453: subcellular location). PARN has no transmembrane segment (UniProt O95453: topology). The tissue IHC pattern has Supported reliability, with medium agreement between antibody staining and RNA expression (HPA: tissue IHC).
| Nuclear and cytoplasmic chromogen appears in glandular cells of colon, cervix, or adrenal gland. | This fits the reported pattern: these glandular populations have High staining, and expression spans both compartments (HPA: tissue IHC). Compare cells within the section before scoring intensity; a High label describes the HPA observation, not a required intensity for every specimen or antibody (HPA: tissue IHC). |
| Staining is confined to the plasma membrane, extracellular material, or a luminal deposit. | That distribution is discordant with reported nuclear and cytoplasmic PARN and its lack of a transmembrane segment (HPA: tissue IHC; UniProt O95453: topology). Treat it as a possible artefact until the pattern is reproduced with suitable controls; compartment alone cannot identify its cause (general IHC practice). |
| An unexpected cell population stains strongly while the selected reference population does not. | Consider cross-reactivity or endogenous chromogenic activity, and inspect the morphology and controls (general IHC practice). The HPA list identifies positive populations but supplies no negative populations, so staining in an unlisted cell type is not, by itself, proof of a false positive (HPA: tissue IHC). |
| Chromogen broadly covers cells and surrounding tissue without readable nuclear or cytoplasmic boundaries. | This is difficult to score as PARN because the reported pattern is cellular and compartmental (HPA: tissue IHC). Compare a no-primary control and review blocking, detection, and washing as general IHC troubleshooting; the supplied sources do not assign a PARN-specific cause to diffuse background (general IHC practice). |
| A selected HPA High population has no visible signal. | Check that the expected cells are present and that detection and counterstaining are interpretable (general IHC practice). An absent signal disagrees with the reported High staining for that population, but HPA reliability is Supported with medium RNA agreement; one negative section cannot establish absent PARN expression (HPA: tissue IHC). |
💡Expected PARN appearanceCall positive a readable nuclear and cytoplasmic signal in an expected population, such as colon glandular cells with reported High staining; isolated membranous or extracellular colour is discordant (HPA: tissue IHC; UniProt O95453: topology).
| Tissue and cell selection | HPA reports High staining in adrenal, cervical, and colon glandular cells; bronchial respiratory epithelial cells; breast adipocytes; and selected glial and cerebellar cells (HPA: tissue IHC). These are reference populations for interpretation, while the broader profile is expression in most tissues (HPA: tissue IHC). |
| Compartment used for scoring | Score nuclear and cytoplasmic staining separately when both can be resolved (HPA: tissue IHC; general IHC practice). UniProt also records a nucleolar nuclear fraction; that annotation does not require a visible nucleolar pattern in every chromogenic section (UniProt O95453: subcellular location). |
| Evidence strength and antibody choice | The tissue pattern is Supported, with medium consistency against RNA expression (HPA: tissue IHC). HPA lists IHC Supported status for HPA006314, HPA012010, and CAB011673; that status supports use of their observations but does not prove every stain is specific (HPA: antibody validation). |
| Molecular forms and fixation evidence | UniProt lists four isoforms and one 1–639 chain, with no signal peptide or propeptide (UniProt O95453: isoforms and processing). The supplied sources do not map antibody epitopes to isoforms or report PARN-specific fixation sensitivity; infer neither isoform coverage nor a fixation effect from the tissue pattern (UniProt O95453; HPA: tissue IHC). |
| IF/ICC Q: what pattern should appear? | HPA reports supported localisation to nuclear speckles in ICC-IF images from A-431, U-251MG, and U2OS cells (HPA: subcellular ICC-IF). Interpret that observation alongside UniProt's nuclear, nucleolar, and cytoplasmic annotations; an IF speckle pattern is not a required readout for chromogenic tissue IHC (HPA: subcellular ICC-IF; UniProt O95453). |
| Situation | Likely cause | Next action |
|---|---|---|
| No signal in colon glandular cells. | Colon glandular cells are reported High, so the result needs review; the source does not identify a specific technical failure (HPA: tissue IHC). | Confirm glandular cells are present, inspect the counterstain, and check primary and detection steps against the chosen antibody's IHC instructions (general IHC practice). |
| Signal appears only on cell borders. | A border-only pattern conflicts with nuclear and cytoplasmic tissue staining and with the absence of a transmembrane segment (HPA: tissue IHC; UniProt O95453: topology). | Review a no-primary control and repeat with the IHC-validated antibody if needed; report the compartment mismatch rather than scoring it as expected PARN (general IHC practice). |
| Brown colour appears in an unlisted cell population. | Cross-reactivity or endogenous chromogenic activity is possible (general IHC practice); HPA provides no negative cell list to settle the interpretation (HPA: tissue IHC). | Compare morphology and no-primary controls, then check whether the expected population also stains in its reported compartments (general IHC practice; HPA: tissue IHC). |
| The whole section has diffuse colour. | Diffuse colour obscures the cellular nuclear and cytoplasmic pattern described for PARN (HPA: tissue IHC); its technical cause is unresolved. | Inspect a no-primary control and review blocking, washes, and detection conditions before changing the interpretation (general IHC practice). |
| Nuclear staining is present but cytoplasmic staining is faint. | Both compartments are reported, while relative intensity is not specified for each tissue in the supplied profile (HPA: tissue IHC). | Record each compartment separately and compare the same cell population across controls; do not require equal nuclear and cytoplasmic intensity (HPA: tissue IHC; general IHC practice). |
| A bright punctate IF nucleus differs from the chromogenic IHC slide. | Nuclear speckles are the supported ICC-IF observation, whereas tissue IHC is described as nuclear and cytoplasmic (HPA: subcellular ICC-IF; HPA: tissue IHC). | Interpret each readout against its own source pattern; use the separate IF/ICC guide for that application (HPA: subcellular ICC-IF; HPA: tissue IHC). |
Experiment evidence
IHC & IF images showing PARN staining
A01501-2 · IHCIHC analysis of PARN using anti-PARN antibody (A01501-2). PARN was detected in paraffin-embedded section of human mammary cancer tissue. Hea
A01501-2 · IHCIHC analysis of PARN using anti-PARN antibody (A01501-2). PARN was detected in paraffin-embedded section of mouse small intestine tissue. He
A01501-2 · IFIF analysis of PARN using anti-PARN antibody (A01501-2). PARN was detected in immunocytochemical section of A549 cell. Enzyme antigen retrie
M01501 · IHCIHC analysis of PARN using anti PARN antibody (M01501). PARN was detected in paraffin-embedded section of human mammary cancer tissue. Heat
M01501 · IFIF analysis of PARN using anti-PARN antibody (M01501). PARN was detected in immunocytochemical section of A549 cells. Enzyme antigen retriev
HPA · Cerebral cortexHuman Protein Atlas IHC, Cerebral cortex. Source: https://www.proteinatlas.org/ENSG00000140694-PARN/tissue/cerebral+cortex#imid_2023624
HPA · ColonHuman Protein Atlas IHC, Colon. Source: https://www.proteinatlas.org/ENSG00000140694-PARN/tissue/colon#imid_2023542
HPA · LiverHuman Protein Atlas IHC, Liver. Source: https://www.proteinatlas.org/ENSG00000140694-PARN/tissue/liver#imid_2023551
HPA · KidneyHuman Protein Atlas IHC, Kidney. Source: https://www.proteinatlas.org/ENSG00000140694-PARN/tissue/kidney#imid_2023552
HPA · ICC-IF A-431Human Protein Atlas immunofluorescence, A-431, antibody HPA006314; green = PARN, blue = nucleus, red = microtubules.
HPA · ICC-IF A-431Human Protein Atlas immunofluorescence, A-431, antibody HPA006314; green = PARN, blue = nucleus, red = microtubules.
← swipe / scroll for more images →
Real IHC / IF data behind the staining-pattern expectations in this section.
Sample controls for PARN IHC & IF
🧪Start with adrenal gland: glandular cells should show strong PARN staining (HPA: High in adrenal gland glandular cells). HPA detects PARN in all 44 scored tissues, so there is no supported negative tissue; use no-primary and isotype controls, and treat any unstained cells on the positive slide as potential internal negatives only if their counterstained nuclei are intact and their signal matches control background (HPA: no negative tissue rows; standard IHC practice).
Positive control tissue: Adrenal gland (Glandular cells, HPA High)
Negative control tissue: None in HPA: PARN is detected in all 44 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 PARN in A-431, U-251MG, U2OS, with annotated localisation: Nuclear speckles (supported) (HPA subcellular).
Technical controls: Run a no-primary, secondary-only control and a nonimmune rabbit IgG isotype control matched to the catalog primary’s immunoglobulin class and, if known, clonality; use PARN knockout material as a biological negative if available (selected IHC caption: rabbit primary; standard IHC practice). Quench endogenous peroxidase and inspect vessel-associated erythrocytes in adrenal sections for residual signal (standard IHC practice).
⚠️Feasibility: A PARN-specific fixation window or fixation effect is unreported, and the A01501-2 paraffin-section caption does not state a fixative (selected IHC caption). Heat retrieval in citrate buffer at pH 6 for 20 minutes is a documented starting condition, although retrieval dependence has not been established (selected IHC caption). The supplied evidence does not establish whether frozen sections or IF are easier; HPA ICC-IF images show nuclear speckles, while adrenal vessel-associated erythrocytes warrant an endogenous peroxidase check in chromogenic IHC (HPA subcellular; standard IHC practice).
HPA tissue IHC evidence for PARN
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 → |
| Breast | Adipocytes | High | Protein (IHC) | HPA → |
| Bronchus | Respiratory epithelial cells | High | Protein (IHC) | HPA → |
| Caudate | Glial cells | High | Protein (IHC) | HPA → |
| Cerebellum | Cells in granular layer | High | Protein (IHC) | HPA → |
Undetected expression · recommended negative controls
| Tissue | Cell type | Level | Evidence | Source |
|---|---|---|---|---|
| None in HPA: PARN is detected in all 44 scored tissues. Use a no-primary (secondary-only) and an isotype control instead. | ||||
Section 3
Advanced PARN IHC Tips
Troubleshoot PARN staining in paraffin sections by checking retrieval, controls, cellular localisation and scoring before interpreting changes in signal.
What retrieval should I try first when PARN staining is weak in paraffin sections?
Start with heat-mediated citrate buffer at pH 6 for 20 minutes on paraffin sections (datasheet A01501-2; selected IHC caption). After retrieval, compare intact tissue regions with a control section processed in the same run, keeping section handling and detection consistent (standard IHC practice). The selected caption used 1 μg/mL primary antibody overnight at 4°C, so reproduce those conditions before changing retrieval (selected IHC caption). If signal remains weak, test a different retrieval buffer on matched sections as a fallback and assess whether nuclear and cytoplasmic staining improves without added background (UniProt O95453 localisation; standard IHC practice).
How should I troubleshoot variable PARN staining between paraffin blocks?
The selected tissue caption describes a paraffin section but does not report its fixative, so PARN sensitivity to fixation is unknown (selected IHC caption). Compare blocks with documented fixation and processing histories, and stain matched sections together using the same citrate pH 6 retrieval (standard IHC practice; selected IHC caption). Examine tissue preservation and whether staining varies across the section before attributing a weak result to PARN abundance (standard IHC practice). Include a control with established PARN staining in every run; HPA reports cytoplasmic and nuclear expression across most tissues, with medium consistency between staining and RNA data (HPA tissue IHC).
Should PARN stain nuclei, cytoplasm, or both in tissue IHC?
Evaluate both nuclear and cytoplasmic staining: UniProt places PARN in the nucleus and cytoplasm, with some nuclear protein in nucleoli (UniProt O95453 localisation). HPA likewise reports cytoplasmic and nuclear expression in most tissues, although its tissue IHC reliability is Supported with medium staining to RNA consistency (HPA tissue IHC). Record the two compartments separately, alongside the proportion of stained cells, so a change in distribution is visible even when overall signal appears similar (standard IHC practice). Nuclear speckles are supported by HPA subcellular imaging, but their fine pattern may be difficult to resolve with chromogenic tissue IHC (HPA subcellular; standard IHC practice).
Could epitope choice explain inconsistent PARN IHC staining?
PARN has 4 annotated isoforms and an R3H domain spanning residues 178–245, so establish which sequence the antibody recognises before comparing samples (UniProt O95453 isoforms and domains). The supplied caption does not identify the antibody epitope; its successful paraffin staining therefore cannot establish detection of every isoform (selected IHC caption; UniProt O95453 isoforms). UniProt also records phosphorylation and acetylation sites, but their effect on this antibody’s tissue staining is unreported (UniProt O95453 modified residues; selected IHC caption). Compare epitope documentation with the isoforms of interest and use an independent antibody or validated control if isoform coverage matters (standard IHC practice).
How can IF help resolve an ambiguous PARN IHC localisation pattern?
For IF/ICC, pair PARN with a marker identifying the cell type under study and compare each channel with the matching chromogenic tissue region (standard IF practice). Choose spectrally separated fluorophores and inspect unstained tissue for autofluorescence before assigning a weak PARN signal to cells (standard IF practice). PARN has no transmembrane segment and is reported in nuclei and cytoplasm, so permeabilise sufficiently for intracellular epitope access while checking cell morphology (UniProt O95453 topology and localisation; standard IF practice). HPA supports nuclear speckles in cell imaging; interpret that fine pattern separately from the broader nuclear and cytoplasmic tissue IHC profile (HPA subcellular; HPA tissue IHC).
What should I check when PARN DAB staining looks diffuse?
The selected paraffin IHC caption used 10% goat serum blocking, a biotinylated secondary antibody and DAB development (selected IHC caption). Inspect a no-primary control for secondary or detection-system background, and include a peroxidase block as a general chromogenic IHC step (standard IHC practice). Compare stained and control sections for diffuse precipitate, tissue edges and poorly preserved areas before scoring intracellular signal (standard IHC practice). Because PARN is reported in both nuclei and cytoplasm, diffuse colour alone is insufficient; assess whether staining follows cell boundaries and plausible compartments (UniProt O95453 localisation; standard IHC practice).
How should I quantify PARN staining across tissue sections? ⚠ ANSWER MARKED FOR VERIFICATION
Define the cell population and tissue region before scoring, then record nuclear and cytoplasmic PARN signals separately (UniProt O95453 localisation; standard IHC practice). For an intensity based comparison, calculate an H-score from the percentage of cells at each staining intensity; report the scoring scale and observer rules (standard IHC practice). Alternatively, report percentage positive cells or positive-cell density per mm² when cell counts answer the research question (standard IHC practice). Normalise comparisons to the same eligible cell population or tissue area, exclude damaged regions consistently, and process control sections alongside samples (standard IHC practice).
How can I distinguish true PARN staining from tissue artefact?
A plausible PARN pattern includes nuclear or cytoplasmic signal in intact cells; UniProt also notes a nucleolar fraction (UniProt O95453 localisation). HPA reports cytoplasmic and nuclear staining in most tissues, with high signal in several specified cell populations, including colon glandular cells and breast adipocytes (HPA tissue IHC). Treat signal confined to section edges, necrotic areas or cell-free material as suspect, and check a no-primary control for endogenous enzyme or detection background (standard IHC practice). Interpret absent or unexpected compartment staining against matched controls and morphology, recognising that HPA rates tissue IHC consistency with RNA expression as medium (HPA tissue IHC; standard IHC practice).
Boster reagents
Best PARN / Poly(A)-specific ribonuclease PARN IHC Antibodies
IHC images cover human mammary cancer tissue for both SKUs and mouse and rat small intestine for A01501-2 (catalog IHC captions); IF/ICC images cover A549 and U251 cells (catalog IF captions).
Real IHC data
Anti-PARN Antibody ®
Cat # A01501-2
Real IHC data
Anti-PARN Antibody ® (monoclonal, 11D8)
Cat # M01501
A01501-2 has IHC images from paraffin sections of human mammary cancer and mouse and rat small intestine, plus an IF/ICC image of A549 cells (A01501-2 image captions). M01501 has an IHC image from a paraffin section of human mammary cancer and IF/ICC images of A549 and U251 cells (M01501 image captions).
Which to pick: For tissue IHC across human, mouse and rat, choose A01501-2: its own images show paraffin sections retrieved with citrate at pH 6; the fixative is unreported (A01501-2 IHC captions). For human tissue IHC with a monoclonal antibody, choose M01501, clone 11D8 (catalog clone): its own paraffin-section image uses EDTA at pH 8, and the fixative is unreported (M01501 IHC caption). For IF/ICC, both list those applications at 2 μg/ml (catalog applications and dilutions); A01501-2 is imaged in A549 cells, while M01501 is imaged in A549 and U251 cells (catalog IF captions).
Each figure is that product's own IHC / IF validation image from its datasheet.
References
- UniProt Consortium. UniProt entry O95453 (PARN_HUMAN, Poly(A)-specific ribonuclease PARN).
- Human Protein Atlas. PARN tissue IHC expression (reliability: Supported).
- Human Protein Atlas. PARN subcellular location (ICC-IF): Localized to the nuclear speckles..
- Human Protein Atlas. PARN antibody validation summary (3 antibodies).
- Poly(A)-specific ribonuclease protein promotes the proliferation, invasion and migration of esophageal cancer cells. World journal of gastroenterology 2023 — PMC10473923.
- Optical Genomic Mapping and Next-Generation Sequencing Identified Retrotransposon Insertion and Missense Variant Disrupting PARN Gene in Dyskeratosis Congenita. Human mutation 2025 — PMC12396913.
- PubMed PMID:9736620 — UniProt-cited evidence.
- PubMed PMID:14702039 — UniProt-cited evidence.
- PubMed PMID:15616553 — UniProt-cited evidence.
Immunohistochemistry protocol sheet for PARN (Poly(A)-specific ribonuclease PARN). Expected localisation Cytoplasmic and nuclear in most tissues (HPA tissue IHC). Antigen retrieval: Citrate pH 6 HIER, heat-mediated (datasheet A01501-2). Validated IHC antibody: A01501-2 at 0.5-1μg/ml (the product's own IHC validation image is shown). Controls (HPA): positive Adrenal gland (Glandular cells); negative None in HPA (detected in all 44 tissues); use no-primary + isotype controls. IHC-P workflow on paraffin sections; fixative unspecified. Protocol steps: 1. Sample: Paraffin-embedded human mammary cancer tissue; fixative not specified (datasheet A01501-2); 2. Fixation: Image fixative and duration unreported (datasheet A01501-2); 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: Citrate pH 6 , 20 min (datasheet A01501-2); 6. Peroxidase block: 3% H2O2, 10 min , room temperature (standard); 7. Blocking: 10% goat serum (datasheet A01501-2); 8. Primary antibody: Rabbit anti-PARN, 0.5-1μg/ml (datasheet A01501-2); 9. Primary incubation: Overnight at 4 °C (datasheet A01501-2). Watch for: Fixation: Keep fixation consistent across sections (standard IHC practice; not target-specific); Caveat: Staining has medium consistency with RNA expression (HPA tissue IHC); Isoform / epitope: 4 isoforms; check epitope coverage (UniProt); Regulation: Low tissue specificity (HPA tissue RNA). Evidence: UniProt O95453, HPA tissue IHC · Supported, HPA ICC-IF · nuclear speckles., Datasheet A01501-2, PMC10473923. QR code links to https://www.bosterbio.com/bosterbio-gene-info-cards/PARN/immunohistochemistry-ihc-guide.