hikeshi Antibody

What is Hikeshi and what is its primary function in cells?

Hikeshi (also known as C11orf73, HSPC138, HSPC179, or HSPC248) is a 22 kDa protein that acts as a specific nuclear import carrier for HSP70 proteins following heat-shock stress. It mediates the nucleoporin-dependent translocation of ATP-bound HSP70 proteins into the nucleus, which is required to protect cells from heat shock damage. Importantly, Hikeshi specifically translocates ATP-bound HSP70 proteins but not ADP-bound HSP70 proteins into the nucleus . Recent research has shown that Hikeshi regulates the nucleocytoplasmic distribution of HSP70 not only under heat-shock conditions but also under non-stressed conditions .

What are the common applications for Hikeshi antibodies in research?

Based on the analyzed research data, Hikeshi antibodies are commonly used in:

What cell lines and tissues have validated Hikeshi expression for antibody testing?

Several studies have confirmed Hikeshi expression in various cell lines and tissues, making them suitable for antibody validation:

• Cell lines: HSC-3 cells (human oral squamous cell carcinoma) , 22Rv1 cells (prostate cancer) , PC-3 cells (prostate cancer) , A375 cells (melanoma) , MCF7 cells (breast adenocarcinoma)

• Tissues: Human lung tissue, mouse brain tissue, human fetal heart tissue

What are the optimal conditions for Hikeshi detection in Western blot applications?

For optimal detection of Hikeshi in Western blot applications:

• Sample preparation: Use non-denaturing or denaturing sample buffer depending on experimental needs. For typical applications, denatured samples work well .

• Protein separation: Standard SDS-PAGE using pre-made polyacrylamide gels (Hikeshi has an observed molecular weight of 22 kDa) .

• Transfer conditions: Use polyvinylidene difluoride (PVDF) membranes for optimal protein transfer .

• Blocking solution: 5% non-fat dry milk (NFDM) in TBST has been successfully used in multiple studies .

• Antibody dilution: Primary antibody dilutions ranging from 1:500 to 1:2000 are typically effective, though this should be optimized for each specific antibody .

• Detection method: HRP-conjugated secondary antibodies with chemiluminescence detection provide good results .

How should I design a Hikeshi knockdown experiment using siRNA?

Based on published methodologies, effective Hikeshi knockdown can be achieved using the following approach:

• siRNA design: Target sequences based on human HIKESHI nucleotide database (GenBank accession no. NM_016401). Multiple studies have successfully used siRNAs targeting different regions of the HIKESHI mRNA .

• Transfection protocol:

  • Seed cells in appropriate media (e.g., E-MEM supplemented with 10% FBS)

  • Replace with Opti-MEM® I Reduced Serum Medium containing 20 nM siRNA and Lipofectamine™ RNAiMAX

  • Incubate at 37°C for 6 hours

  • Replace medium with complete growth medium

  • Maintain cells at 37°C for 1-2 days before experiments

• Validation: Confirm knockdown efficiency using both RT-qPCR and Western blot analysis. Effective knockdown typically shows 80-90% reduction in mRNA and protein levels .

• Controls: Always include a negative control siRNA (e.g., siRNA targeting firefly luciferase) to account for non-specific effects of transfection .

What protocols are recommended for immunocytochemistry and immunofluorescence detection of Hikeshi?

For optimal immunocytochemical and immunofluorescence detection of Hikeshi:

• Cell fixation: Standard paraformaldehyde fixation (4% PFA for 15-20 minutes) is generally effective.

• Permeabilization: Use 0.1-0.5% Triton X-100 in PBS to facilitate antibody access to intracellular targets.

• Blocking: Use 5% normal serum (goat or donkey depending on secondary antibody species) with 0.3% Triton X-100 in PBS.

• Antibody dilution: Primary antibodies have been successfully used at dilutions ranging from 1:300 to 1:1200 .

• Co-localization studies: When examining Hikeshi's role in HSP70 nuclear translocation, co-staining with HSP70 antibodies can provide valuable information about their spatial relationship, especially before and after heat shock treatment .

How can I validate the specificity of a Hikeshi antibody?

To confirm antibody specificity:

• Positive and negative controls: Include known Hikeshi-expressing cells (e.g., PC-3, A375) as positive controls . For negative controls, use Hikeshi knockdown cells generated by siRNA treatment .

• Multiple detection methods: Confirm results using different techniques (e.g., WB, IF, IHC) to ensure consistent findings.

• Band size verification: In Western blot, confirm that the detected band matches the predicted molecular weight of Hikeshi (21-22 kDa) .

• Subcellular localization pattern: Verify that the antibody detects Hikeshi in expected subcellular compartments (cytoplasmic and nuclear localization has been reported) .

• Cross-reactivity testing: Test the antibody across multiple species if working with non-human models. Several Hikeshi antibodies show reactivity with human, mouse, and rat samples .

What are common issues with Hikeshi antibodies in Western blotting and how can they be resolved?

Common problems and solutions include:

How can I optimize the signal-to-noise ratio when using Hikeshi antibodies for immunohistochemistry?

Based on research protocols, optimize IHC signal-to-noise ratio by:

• Antigen retrieval: Use TE buffer pH 9.0 for optimal antigen retrieval, though citrate buffer pH 6.0 may also be effective for certain applications .

• Blocking endogenous peroxidase: Incubate sections with 0.3% H₂O₂ in methanol for 30 minutes before immunostaining.

• Antibody dilution optimization: Test a range of dilutions (1:20-1:200) to identify optimal signal-to-noise ratio .

• Background reduction: Use appropriate blocking serum (5-10%) and include 0.1-0.3% detergent (Triton X-100 or Tween-20) to reduce non-specific binding.

• Incubation conditions: Optimize temperature and duration (4°C overnight incubation may improve specific binding and reduce background).

• Controls: Include both positive controls (tissues known to express Hikeshi) and negative controls (primary antibody omission and/or isotype controls).

How can Hikeshi antibodies be used to study the relationship between heat shock response and cancer?

Several studies have identified important relationships between Hikeshi and cancer that can be investigated using specific antibody-based approaches:

• Differential expression analysis: Compare Hikeshi expression levels between normal and cancerous tissues using IHC and WB. Research has shown altered expression in prostate cancer with different Gleason patterns .

• Therapeutic sensitivity monitoring: Investigate how Hikeshi levels affect cancer cell sensitivity to hyperthermia treatment by analyzing:

  • HSP70 nuclear translocation before and after heat shock using immunofluorescence

  • Cell viability following combined Hikeshi knockdown and mild hyperthermia treatment

  • Changes in ERK phosphorylation using phospho-specific antibodies

• Mechanistic studies: Examine how Hikeshi affects HSF1 activity and subsequent heat shock protein expression using:

  • ChIP assays to assess HSF1 binding to target promoters

  • Reporter gene assays to measure HSF1 transcriptional activity

  • Co-immunoprecipitation to detect Hikeshi-HSP70 interactions

Research has demonstrated that HIKESHI silencing significantly enhances the sensitivity of cancer cells to mild hyperthermia (42°C), suggesting potential therapeutic applications .

What methodologies can be used to study Hikeshi's role in nucleocytoplasmic transport of HSP70?

Advanced methodologies to investigate Hikeshi's transport function include:

• Nuclear/cytoplasmic fractionation: Separate nuclear and cytoplasmic fractions before and after heat shock in control and Hikeshi-knockdown cells, then analyze HSP70 distribution by Western blot .

• Live-cell imaging: Use fluorescently tagged HSP70 and Hikeshi to track their dynamic localization during heat shock response in real-time.

• FRAP (Fluorescence Recovery After Photobleaching): Measure the kinetics of HSP70 nuclear import in the presence or absence of Hikeshi.

• Nucleoporin interaction studies: Investigate Hikeshi interaction with nuclear pore components using proximity ligation assays or co-immunoprecipitation.

How can Hikeshi antibodies be used to investigate its role in neurodegenerative diseases?

Evidence suggests Hikeshi may be relevant to neurodegenerative conditions through its regulatory effects on nuclear proteostasis:

• Protein aggregation assays: Study how Hikeshi depletion affects nuclear aggregation of polyglutamine proteins associated with neurodegenerative diseases .

• Co-localization studies: Examine whether Hikeshi co-localizes with disease-associated protein aggregates in patient samples or model systems.

• Stress response analysis: Investigate how Hikeshi levels affect the cellular response to various stressors (oxidative, proteotoxic) relevant to neurodegeneration:

  • Measure stress-induced gene expression changes

  • Analyze protein aggregation patterns

  • Assess cell survival under stress conditions

• Mutation analysis: Study how disease-associated mutations (e.g., the V54L mutation associated with infantile leukoencephalopathy in HLD13) affect Hikeshi function and HSP70 nuclear translocation .

How should I interpret changes in Hikeshi expression levels in different experimental contexts?

When analyzing Hikeshi expression data:

• Baseline expression: Establish normal expression levels in your experimental system using multiple detection methods (WB, qPCR, IF) for comprehensive analysis.

• Stress-induced changes: Consider that Hikeshi expression can be moderately upregulated (approximately 1.3-fold) following heat shock , which may affect interpretation of results from stress experiments.

• Tissue/cell type specificity: Account for potential variability in expression across different tissues and cell types when comparing results.

• Correlation with HSP70 dynamics: Analyze Hikeshi expression changes in relation to HSP70 nuclear translocation, as these processes are functionally linked .

• Pathological contexts: Consider that altered Hikeshi expression in disease states (e.g., cancer) may reflect adaptive responses to cellular stress or contribute to disease pathogenesis .

What controls should be included when studying the effects of Hikeshi knockdown on HSP70 nuclear import?

To ensure robust interpretation of Hikeshi knockdown experiments:

• Knockdown validation: Confirm successful Hikeshi depletion at both mRNA (RT-qPCR) and protein (Western blot) levels.

• Negative control siRNA: Include a non-targeting siRNA (e.g., siLuc) to control for non-specific effects of the transfection procedure .

• Heat shock controls: Include both non-heat-shocked and heat-shocked conditions for comprehensive analysis. Standard heat shock conditions used in published studies include 42-43°C for 60-90 minutes .

• Rescue experiments: Reintroduce wild-type Hikeshi to confirm that observed phenotypes are specifically due to Hikeshi depletion rather than off-target effects.

• HSP70 isoform specificity: Consider that Hikeshi may differently affect various HSP70 family members, necessitating isoform-specific antibodies for detailed analysis.

• Temporal analysis: Examine HSP70 localization at multiple time points after heat shock to capture dynamic changes in nuclear import kinetics.

How can I differentiate between direct and indirect effects of Hikeshi on cellular processes?

To distinguish direct from indirect effects:

• Temporal analyses: Examine the timing of changes following Hikeshi manipulation—immediate effects are more likely to be direct, while delayed effects may be indirect.

• Protein interaction studies: Use co-immunoprecipitation or proximity ligation assays to identify direct binding partners of Hikeshi.

• Structure-function analyses: Generate and test Hikeshi mutants with altered binding properties to identify domains critical for specific functions.

• Pathway inhibition: Combine Hikeshi manipulation with inhibitors of potential downstream pathways (e.g., U0126 for MAPK/ERK inhibition) to determine if effects are mediated through these pathways .

• Global analyses: Compare transcriptomic or proteomic changes in control versus Hikeshi-depleted cells to identify broader effects on cellular pathways.

Research has shown that Hikeshi depletion affects ERK2 phosphorylation under mild hyperthermia conditions, and this effect can be abolished by U0126 pretreatment, demonstrating pathway-specific effects .