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Overview
This pre-designed siRNA set enables sequence-specific knockdown of the human KRTAP1-4 gene (NCBI Gene ID: 728255) in human cell lines. Each set is supplied as HPLC-purified, chemically synthesized double-stranded RNA oligonucleotides in lyophilized form, ready for reconstitution and transfection. Two size formats are available: Set A (SI008433A, 3 siRNA sequences at 3×5 nmol) and Set B (SI008433B, 4 siRNA sequences at 4×10 nmol), providing flexibility for screening or extended knockdown studies.
Key Elements and Design Rationale
- Multiple independent sequences: Both sets include 3 or 4 distinct siRNA duplexes targeting different regions of the KRTAP1-4 mRNA, increasing the probability of achieving effective knockdown and providing built-in sequence redundancy for experimental confidence.
- GAPDH positive control: Included in every set to verify transfection efficiency and confirm that the RNAi machinery is functionally active in the cell model used.
- Scrambled negative control (si-NC): A non-targeting scrambled duplex is included to control for non-specific effects of the transfection reagent and dsRNA delivery.
- FAM-labeled negative control: Fluorescently labeled NC allows direct visualization of transfection efficiency by fluorescence microscopy or flow cytometry prior to mRNA or protein readout.
- HPLC purification: Each duplex is HPLC-purified to remove truncated sequences and reagent impurities that could contribute to off-target effects.
Biological Background
The KRTAP1-4 gene (Gene ID: 728255) encodes a human protein involved in cellular function. siRNA-mediated knockdown of KRTAP1-4 is commonly applied to assess the contribution of this gene to cell proliferation, signaling, or metabolic pathways depending on the biological context. The RNA interference (RNAi) pathway exploits the RISC complex: after cellular entry, the sense (passenger) strand is degraded, and the antisense (guide) strand directs RISC-mediated cleavage of complementary KRTAP1-4 mRNA, leading to mRNA degradation and reduced protein expression.
Research Relevance and Current Trends
- Functional genomics screens: Pre-designed siRNA sets targeting individual genes such as KRTAP1-4 are routinely used in arrayed or pooled functional screens to identify gene dependencies in cancer cell lines, primary cells, and disease models.
- Pathway validation: After identifying candidate genes by transcriptomics or proteomics, researchers commonly use siRNA knockdown to confirm the functional role of a target like KRTAP1-4 before advancing to stable KO models.
- Target prioritization: The availability of multiple non-overlapping siRNA sequences per set supports orthogonal knockdown confirmation, a best practice for reducing false-positive conclusions in gene function studies.
Common Research Applications
- mRNA knockdown validation by RT-qPCR: Following transfection, mRNA levels of KRTAP1-4 are typically measured at 24–72 h post-transfection using RT-qPCR, with knockdown efficiency calculated relative to a reference gene.
- Protein-level knockdown by Western blot: Knockdown at the protein level is assessed 48–96 h post-transfection. Note that mRNA and protein knockdown kinetics may differ depending on protein turnover rate.
- Phenotypic assays: Once knockdown is confirmed, researchers use the optimized siRNA sequence to assess effects on cell viability, proliferation, migration, apoptosis, or signaling pathway activation.
- FAM-NC-guided optimization: The FAM-labeled negative control enables parallel assessment of transfection efficiency (≥80% is typically required) before committing target-specific siRNA to experiments.
Notes for Experimental Interpretation
- Transfection efficiency: The FAM-labeled NC should be used first to optimize reagent and siRNA concentrations for the specific cell line used.
- Off-target effects: Inclusion of the scrambled negative control and comparison of multiple independent KRTAP1-4 siRNA sequences helps distinguish on-target from off-target phenotypes.
- mRNA vs. protein knockdown: Both mRNA (RT-qPCR) and protein (WB) readouts are recommended for complete characterization.
- Cell-type considerations: Knockdown efficiency may vary across different human cell lines due to differences in transfection efficiency, RNAi machinery activity, and baseline KRTAP1-4 expression levels.
Kit Components
Set A (SI008433A) — 3 siRNA sequences × 5 nmol
- Human KRTAP1-4 siRNA-1: 5 nmol (HPLC)
- Human KRTAP1-4 siRNA-2: 5 nmol (HPLC)
- Human KRTAP1-4 siRNA-3: 5 nmol (HPLC)
- GAPDH siRNA Positive Control: 2.5 nmol (HPLC)
- siRNA Negative Control: 2.5 nmol (HPLC)
- FAM-labeled siRNA Negative Control: 2.5 nmol (HPLC)
Set B (SI008433B) — 4 siRNA sequences × 10 nmol
- Human KRTAP1-4 siRNA-1: 10 nmol (HPLC)
- Human KRTAP1-4 siRNA-2: 10 nmol (HPLC)
- Human KRTAP1-4 siRNA-3: 10 nmol (HPLC)
- Human KRTAP1-4 siRNA-4: 10 nmol (HPLC)
- GAPDH siRNA Positive Control: 2.5 nmol (HPLC)
- siRNA Negative Control: 2.5 nmol (HPLC)
- FAM-labeled siRNA Negative Control: 2.5 nmol (HPLC)
siRNA Mechanism of Action
Small interfering RNA (siRNA) is a class of chemically synthesized, double-stranded RNA molecule typically 21–23 nucleotides in length. Each duplex consists of two strands:
- Passenger strand (sense strand) — matches the target mRNA sequence; degraded after cellular entry.
- Guide strand (antisense strand) — complementary to the target mRNA; directs the silencing machinery.
Intracellular Pathway
- Delivery: siRNA duplexes are introduced into cells via a transfection reagent or other delivery method, enabling endosomal escape into the cytoplasm.
- RISC loading: The duplex is incorporated into the RNA-induced silencing complex (RISC). The passenger strand is cleaved and discarded; the guide strand is retained.
- Target recognition: The guide strand base-pairs with complementary sequences in the target mRNA through Watson–Crick hybridization.
- mRNA cleavage: The Argonaute 2 (AGO2) endonuclease within RISC cleaves the target mRNA at the site of complementarity, triggering its degradation.
- Protein reduction: Loss of target mRNA reduces ribosomal translation, leading to decreased protein expression — typically detectable 48–96 hours post-transfection.
Key Design Features of This Set
- Multiple sequences: 3 (Set A) or 4 (Set B) independent siRNA duplexes targeting distinct regions of the same mRNA increase the probability of effective silencing and support orthogonal confirmation.
- HPLC purification: Chromatographic purification removes truncated oligonucleotides and synthesis by-products that could trigger non-specific immune responses or off-target effects.
- Lyophilized format: Supplied as dry powder for stable ambient-temperature shipping; reconstituted in DEPC (RNase-free) water prior to use.
Overview
The protocol below uses a 24-well plate as the reference format. Scale reagent volumes proportionally for other plate formats using the table provided. All amounts are calculated per well.
Before You Begin
- Reconstitute lyophilized siRNA in DEPC (RNase-free) water to a 20 µM stock concentration (1 OD ≈ 2.5 nmol; add 150 µL DEPC water per 1 OD to reach 20 µM).
- Centrifuge each tube at 10,000 rpm for 30 seconds before opening to concentrate powder at the bottom.
- Prepare single-use aliquots and store at −20°C to avoid repeated freeze–thaw cycles.
- Seed adherent cells at 0.5–2.0 × 10⁵ cells/well in 500 µL complete medium one day before transfection. Optimal cell density at transfection: 60–80% confluence.
Transfection Procedure (24-well format)
- Place transfection reagent at room temperature; mix gently before use.
- Prepare Tube A (reagent mix): Add 2 µL transfection reagent to 50 µL serum-free medium or Opti-MEM. Mix gently; incubate 5 min at room temperature.
- Prepare Tube B (siRNA mix): Add 2 µL siRNA stock (20 µM = 40 pmol) to 50 µL serum-free medium or Opti-MEM. Mix gently; incubate 5 min at room temperature.
- Combine: Add Tube A to Tube B, mix gently, and incubate 15–20 min at room temperature to allow complex formation.
- Add 100 µL of the transfection complex to each well. Shake plate gently to distribute evenly.
- After 6–8 hours, replace medium with complete growth medium.
- Incubate cells and harvest at the appropriate time point for your readout.
Recommended Harvest Time Points
- mRNA knockdown (RT-qPCR): 24–72 hours post-transfection
- Protein knockdown (Western blot / ELISA): 48–96 hours post-transfection
Scale Reference — Reagent Amounts by Plate Format
| Plate Format | Well Area | Medium Volume | Opti-MEM (×2 tubes) | siRNA Amount | Transfection Reagent |
|---|---|---|---|---|---|
| 96-well | 0.3 cm² | 100 µL | 2 × 10 µL | 20 pmol | 1 µL |
| 24-well | 2.0 cm² | 500 µL | 2 × 50 µL | 40 pmol | 2 µL |
| 12-well | 4.0 cm² | 1 mL | 2 × 100 µL | 80 pmol | 4 µL |
| 6-well | 10.0 cm² | 2 mL | 2 × 200 µL | 150 pmol | 7.5 µL |
| 60 mm dish | 20.0 cm² | 5 mL | 2 × 500 µL | 300 pmol | 15 µL |
| 10 cm dish | 60.0 cm² | 15 mL | 2 × 1 mL | 600 pmol | 30 µL |
Note: 20 µM is the recommended storage concentration; 2 µL of 20 µM stock contains 40 pmol siRNA.
Step 1 — Confirm Transfection Efficiency (FAM-NC)
Before evaluating KRTAP1-4 knockdown, confirm that transfection efficiency is ≥80% using the included FAM-labeled negative control. Transfect cells with FAM-NC under the same conditions as your target siRNA, then compare bright-field and dark-field (fluorescence) images 6–8 hours post-transfection. If ≥80% of cells are fluorescent under normal growth conditions, transfection efficiency is sufficient to proceed.
Low transfection efficiency is the most common cause of insufficient knockdown — always verify this step before interpreting KRTAP1-4 silencing results.
Step 2 — Assess mRNA Knockdown by RT-qPCR
Harvest cells 24–72 hours post-transfection and extract total RNA. Run RT-qPCR for KRTAP1-4 using a reference gene (e.g., beta-actin or GAPDH) for normalization. Calculate knockdown efficiency using the ΔΔCt method:
- ΔCt = Cttarget (KRTAP1-4) − Ctreference gene
- ΔΔCt = ΔCtsiRNA group − ΔCtnegative control group
- Knockdown efficiency = (1 − 2−ΔΔCt) × 100%
Evaluate results from all siRNA sequences in the set independently. A knockdown efficiency of ≥70% in at least one sequence confirms effective silencing of KRTAP1-4.
Step 3 — Assess Protein Knockdown by Western Blot
Harvest cells 48–96 hours post-transfection for protein-level analysis. Run Western blot using an appropriate anti-KRTAP1-4 antibody, with GAPDH or another housekeeping protein as a loading control. Note that mRNA and protein knockdown kinetics may differ depending on the half-life of the KRTAP1-4 protein.
Interpreting Your Controls
| Control | Expected Result | If Result Differs |
|---|---|---|
| Negative control (si-NC) | No knockdown of KRTAP1-4; <20% difference vs. mock group | Investigate non-specific effects of transfection reagent or dsRNA |
| GAPDH positive control | ≥70% knockdown of GAPDH mRNA | RNAi pathway may be impaired; check transfection conditions |
| Mock group (no siRNA) | Within ±20% of si-NC group | If outside range, investigate reagent toxicity or handling variables |
Knockdown Performance Guarantee
When transfection efficiency reaches ≥80% (confirmed by FAM-labeled negative control), we guarantee that at least one of the siRNA sequences in the set will achieve ≥70% knockdown efficiency at the mRNA level.
What Happens If the Guarantee Is Not Met
- Free redesign (first round): If the guaranteed knockdown is not achieved, we will redesign and resynthesize 2 new siRNA sequences at no charge.
- Refund (if redesign also fails): If the resynthesized sequences still do not achieve the guaranteed knockdown, a full refund will be issued.
Requirements to Claim the Guarantee
- FAM-NC transfection images: Bright-field and dark-field (fluorescence) images confirming ≥80% transfection efficiency in the cell model used.
- RT-qPCR raw data: Raw Ct values for the target gene and reference gene across all siRNA groups, negative control, and mock group, demonstrating that knockdown did not meet the ≥70% threshold.
Important Limitations
- The guarantee applies to mRNA-level knockdown only. Protein-level results (e.g., Western blot alone) are not sufficient to claim the guarantee.
- If only Western blot data is provided, one free redesign will be offered; however, refunds do not apply based on protein data alone.
- The guarantee assumes standard transfection conditions as described in the transfection protocol.
Contact Us
For guarantee claims or return inquiries, please contact us at support@biohippo.com. Please include your order number, cell line used, and all required documentation when submitting a claim.
Need a configuration beyond the standard pre-designed siRNA set? We can help tailor your order for screening, validation, or scale-up studies. Custom and add-on options may include your preferred set format (Set A with 3 target-gene siRNAs at 5 nmol each, or Set B with 4 target-gene siRNAs at 10 nmol each), additional target-specific siRNA tubes, repeat or bulk packaging, and extra control reagents such as GAPDH siRNA positive control, negative control, or FAM-labeled negative control. We can also discuss larger synthesis scales, project-based quantity planning, and supply preferences aligned with the standard product format, including HPLC-purified, lyophilized siRNA for DEPC water reconstitution. For custom requests or add-on inquiries, please contact us at support@biohippo.com. Our team will review your study needs and get back to you with the best-fit option.
Methodology References
- Fire A, Xu S, Montgomery MK, et al. Potent and specific genetic interference by double-stranded RNA in Caenorhabditis elegans. Nature. 1998;391(6669):806–811. https://doi.org/10.1038/35888
- Elbashir SM, Harborth J, Lendeckel W, et al. Duplexes of 21-nucleotide RNAs mediate RNA interference in cultured mammalian cells. Nature. 2001;411(6836):494–498. https://doi.org/10.1038/35078107
- Reynolds A, Leake D, Boese Q, et al. Rational siRNA design for RNA interference. Nature Biotechnology. 2004;22(3):326–330. https://doi.org/10.1038/nbt936
- Jackson AL, Linsley PS. Recognizing and avoiding siRNA off-target effects for target identification and therapeutic application. Nature Reviews Drug Discovery. 2010;9(1):57–67. https://doi.org/10.1038/nrd3054
- Kaelin WG Jr. Use and abuse of RNAi to study mammalian gene function. Science. 2012;337(6093):421–422. https://doi.org/10.1126/science.1225150
Gene-Specific Resources — KRTAP1-4
- NCBI Gene: https://www.ncbi.nlm.nih.gov/gene/728255 — Official gene record, reference sequences, isoforms, and expression data for human KRTAP1-4.
- PubMed — siRNA knockdown literature: Search PubMed for KRTAP1-4 siRNA studies — Browse publications on KRTAP1-4 knockdown, functional studies, and pathway roles.
- UniProtKB: Search UniProt for human KRTAP1-4 protein — Protein function, domains, post-translational modifications, and interaction data.
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