ASIC3 Antibody

What is ASIC3 and what is its physiological function?

ASIC3 (also known as ACCN3, SLNAC1, TNAC1, or hASIC3) is a member of the degenerin/epithelial Na+ channel (DEG/ENaC) superfamily. It functions as a cation channel with high affinity for sodium that is gated by extracellular protons and inhibited by the diuretic amiloride . The channel generates a characteristic biphasic current with both fast inactivating and slow sustained phases.

Physiologically, ASIC3 plays several important roles in the nervous system. In sensory neurons, it mediates pain induced by acidosis that occurs in ischemic, damaged or inflamed tissue, suggesting direct involvement in hyperalgesia . Beyond pain sensation, evidence suggests ASIC3 may play a role in mechanoreception. The channel is predominantly expressed in dorsal root ganglia (DRG) neurons and nociceptors involved in pain detection and transmission .

Recent research has revealed that ASIC3 exacerbates psoriatic inflammation through sensory neurogenic pathways, indicating its importance in neuro-immune interactions . Structurally, ASIC3 consists of two transmembrane spanning domains, a large extracellular domain, and short intracellular N- and C-termini, with a molecular mass of approximately 58 kDa .

How can I validate the specificity of an ASIC3 antibody?

Validating ASIC3 antibody specificity is critical for reliable research outcomes. Multiple complementary approaches should be employed:

Genetic controls:

• Testing in ASIC3 knockout tissues: A specific ASIC3 antibody should show no immunoreactivity in tissues from ASIC3 knockout mice.

• siRNA or shRNA knockdown: Reduced antibody signal should correlate with knockdown efficiency .

Peptide competition assays:

• Pre-incubation of the antibody with the immunizing peptide should abolish specific immunolabeling.

• For example, Anti-ASIC3 Antibody can be validated by pre-incubation with ASIC3 Blocking Peptide .

Heterologous expression systems:

• Testing in ASIC3-transfected cells alongside non-transfected controls.

• The antibody should specifically label ASIC3-transfected cells but not control cells.

• Cross-reactivity testing with related proteins is essential; for instance, some validated ASIC3 antibodies do not label cells transfected with ASIC1a, 1b or 2 .

Regional expression control:

• Absence of labeling in tissues known to lack ASIC3 expression (e.g., brainstem, which has no reported ASIC3 mRNA).

• Positive labeling in tissues with confirmed ASIC3 expression (e.g., DRG neurons) .

Technical controls:

• Primary antibody omission should result in no specific labeling .

• Western blot validation should detect a band of the expected molecular weight (58 kDa for ASIC3) .

What tissue types express ASIC3 channels?

ASIC3 exhibits a distinct expression pattern that varies between species:

Within sensory neurons, ASIC3 is frequently co-expressed with other sensory markers such as NF200 (myelinated neurons), TrkA (NGF-sensitive neurons), CGRP (peptidergic nociceptors), and TRPV1 (polymodal nociceptors) . Double or triple labeling techniques can reveal these relationships in tissue sections.

The expression of ASIC3 can be upregulated in pathological conditions, with increased ASIC3-immunoreactive nerves observed in joint inflammation and inflammatory skin conditions . Understanding these tissue-specific expression patterns is essential for interpreting experimental results and developing targeted therapeutic approaches.

How do ASIC3 channels contribute to inflammatory diseases like psoriasis?

Recent research has revealed a significant role for ASIC3 channels in exacerbating psoriatic inflammation through sensory neurogenic pathways . The mechanisms involve complex bidirectional neuro-immune interactions:

ASIC3 activation and neuropeptide release:

• ASIC3 channels in sensory neurons can be activated by acidic microenvironments present in inflamed tissues.

• Activation of ASIC3 in DRG neurons triggers the release of neuropeptides, particularly CGRP (Calcitonin Gene-Related Peptide).

• Studies show that acidic (pH 5.5) stimulation increases CGRP concentration in media from wild-type DRG cultures but not from ASIC3-deficient cultures .

• The non-proton ASIC3 agonist GMQ (2-guanidine-4-methylquinazoline) also promotes CGRP release from wild-type neurons .

• This release can be blocked by ASIC antagonists like amiloride or by blocking vesicular exocytosis with botulinum toxin A (BoNT/A) .

Experimental evidence from psoriasis models:

• ASIC3 knockout mice (Asic3−/−) are less susceptible to psoriatic inflammation induced by imiquimod (IMQ).

• Compared to wild-type mice, ASIC3-deficient mice show less severe splenomegaly, reduced skin thickening, decreased epidermal proliferation (fewer Ki67-positive cells), and lower levels of type 17 cytokines (IL-23, IL-17, and IL-22) in lesioned skin .

Neuron-specific ASIC3 contribution:

• Conditional deletion of ASIC3 in nociceptors (using Nav1.8-Cre::Asic3flox/flox mice) replicates the protective effects of global ASIC3 deletion .

• Targeted knockdown of ASIC3 using AAV-delivered shRNA similarly reduces psoriatic inflammation.

• Rescue experiments show that re-expression of ASIC3 solely in Nav1.8+ nociceptors is sufficient to aggravate psoriatic inflammation .

These findings suggest that targeting neuronal ASIC3 channels may provide a novel approach for treating psoriasis and potentially other inflammatory skin diseases by interrupting the pro-inflammatory signaling loop between neural and immune systems.

How does ASIC3 interact with other ion channels in nociceptive pathways?

ASIC3 functions within a complex network of ion channels in nociceptive neurons, with numerous functional interactions that modulate pain signaling:

ASIC3 and TRPV1 (Transient Receptor Potential Vanilloid 1):

• ASIC3 and TRPV1 show substantial, though not complete, co-localization in DRG neurons and skin afferents .

• While TRPV1 responds to heat, capsaicin, and mild acidosis, ASIC3 is activated by stronger acidic stimuli.

• ASIC3 deficiency provides comparable improvement in psoriatic inflammation as TRPV1+ nociceptor ablation, suggesting complementary roles in inflammatory processes .

ASIC3 and voltage-gated sodium channels:

• ASIC3 is predominantly expressed in Nav1.8-positive nociceptors, which is why Nav1.8-Cre mice enable targeted genetic manipulation of ASIC3 in nociceptors .

• Nav1.8 likely initiates action potentials following ASIC3-mediated depolarization in nociceptive neurons.

ASIC3 heteromeric assemblies:

• ASIC3 can assemble with other ASIC subunits (ASIC1, ASIC2) to form heteromeric channels .

• Heteromeric channels display altered pH sensitivity, current kinetics, and pharmacological profiles compared to homomeric ASIC3 .

• The composition of ASIC heteromers varies across different neuronal populations.

ASIC3 and calcium signaling pathways:

• ASIC3 activation leads to membrane depolarization, which can activate voltage-gated calcium channels.

• The resulting calcium influx triggers CGRP release from sensory neurons .

• Botulinum toxin A (BoNT/A) inhibits this vesicular exocytosis, reducing ASIC3-mediated inflammatory responses .

Understanding these interactions is crucial for developing targeted pain therapeutics that modulate specific aspects of nociceptive signaling without disrupting normal sensory function.

How can conditional knockout models help elucidate ASIC3's tissue-specific functions?

Conditional knockout (cKO) models provide powerful tools for dissecting ASIC3's diverse functions in different tissues and cell types:

Advantages over conventional knockout approaches:

• Conventional ASIC3 knockouts eliminate the channel from all tissues, complicating interpretation of phenotypes.

• Conditional knockouts allow tissue-specific or cell-type-specific deletion, minimizing developmental compensation that may occur in global knockouts.

• This approach enables investigation of ASIC3 function in adult animals, avoiding developmental confounds.

Implementation strategies for ASIC3 conditional models:

• Generation of floxed ASIC3 alleles (Asic3flox/flox) with loxP sites flanking critical exons.

• Crossing with tissue-specific Cre recombinase-expressing lines.

• Viral delivery of Cre to specific tissues or regions for spatial control.

Neuron-specific ASIC3 deletion models:

• Nav1.8-Cre::Asic3flox/flox mice provide selective deletion in nociceptive neurons.

• These mice exhibit lower spleen weight, reduced epidermal proliferation, and decreased inflammatory cytokine production compared to controls in psoriasis models .

• This demonstrates that nociceptor-specific ASIC3 deletion is sufficient to attenuate psoriatic inflammation.

Complementary rescue approaches:

• AAV vectors containing ASIC3 shRNA with double-floxed inverted orientation (DIO) coding sequence for shRNA-resistant FLAG-ASIC3-2A-mCherry.

• When injected into Nav1.8-Cre mice, this enables specific re-expression of ASIC3 in Nav1.8+ nociceptors.

• Re-expression solely in nociceptors is sufficient to aggravate inflammation, confirming the neuronal origin of ASIC3's pro-inflammatory effects .

Visualizing ASIC3 expression patterns:

• ASIC3-myc reporter mice enable visualization of ASIC3 distribution.

• These models reveal substantial co-localization of ASIC3 with TRPV1 in DRG tissues and skin afferents .

• Such reporter lines can be combined with conditional approaches to confirm cell-specific deletion.

These approaches have revealed that ASIC3's role in exacerbating psoriatic inflammation is specifically mediated by its expression in nociceptive neurons, demonstrating the power of conditional strategies for dissecting complex physiological mechanisms.

What controls should be included when using ASIC3 antibodies for immunohistochemistry?

Rigorous control experiments are essential when using ASIC3 antibodies for immunohistochemistry to ensure specificity and reliability:

Negative controls:

• Primary antibody omission: Process tissues through all steps except primary antibody incubation; should show no specific labeling .

• Peptide competition: Pre-incubate ASIC3 antibody with excess immunizing peptide (e.g., ASIC3 Blocking Peptide) to abolish specific labeling .

• Genetic models: Include tissues from ASIC3 knockout animals, which should show no specific labeling .

Positive controls:

• Known ASIC3-expressing tissues: Include samples from tissues with confirmed ASIC3 expression (e.g., DRG).

• Species-appropriate tissues: Ensure controls match the species being studied (important as ASIC3 expression patterns differ between species) .

Specificity controls:

• Cross-reactivity testing: Examine tissues expressing related proteins (e.g., other ASIC family members).

• Regional expression control: Include brain regions known to lack ASIC3 expression (e.g., brainstem) .

• Antibody validation with multiple antibodies: Compare labeling patterns using antibodies targeting different epitopes of ASIC3 .

Technical controls:

• Secondary antibody controls (omit primary antibody).

• Autofluorescence controls (especially important in tissues like skin).

Multiple labeling controls:

• Single primary controls: When performing double/triple labeling, include controls with each primary antibody alone.

• Cross-reactivity controls: Ensure secondary antibodies don't cross-react with primaries from different species .

These comprehensive controls not only validate the specificity of ASIC3 antibody labeling but also help optimize experimental conditions and provide confidence in interpreting results from complex tissues.

What are the advantages and limitations of different ASIC3 antibodies targeting different epitopes?

ASIC3 antibodies targeting different epitopes offer complementary strengths and limitations that should be considered when designing experiments:

N-terminus targeting antibodies:

• Target sequence: Peptide corresponding to amino acid residues near the N-terminus of ASIC3 .

• Advantages:

  • Access to intracellular domain that may be less affected by glycosylation.

  • Suitable for detecting full-length ASIC3.

  • Works well in Western blot applications (detects 58 kDa band) .

• Limitations:

  • May not detect N-terminally truncated variants.

  • Inaccessible in non-permeabilized cells (requires permeabilization for ICC/IHC).

  • May be affected by intracellular protein-protein interactions.

Extracellular domain targeting antibodies:

• Target sequence: Extracellular domain of ASIC3 (e.g., amino acid residues 285–304) .

• Advantages:

  • Accessible in intact cells without permeabilization.

  • Potential for live cell labeling applications.

  • Validated in knockout tissues with complete absence of labeling.

  • Does not cross-react with other ASIC subtypes (ASIC1a, 1b, 2) .

• Limitations:

  • May be affected by glycosylation or protein folding.

  • Potentially sensitive to fixation conditions.

  • May have different accessibility in heteromeric vs. homomeric channels.

Comparison of different host species antibodies:

Application-specific considerations:

• Western blotting: N-terminal antibodies often perform well, with expected band size of 58 kDa .

• Immunohistochemistry: Both domains can work, but may require different fixation/permeabilization protocols .

• Multiple labeling: Different host species antibodies (rabbit vs. guinea pig) allow for simultaneous detection of ASIC3 with other markers .

Understanding these differences allows researchers to select the most appropriate ASIC3 antibody for specific applications and experimental questions, often using multiple antibodies in complementary approaches for the most robust results.

How should samples be prepared for optimal ASIC3 antibody labeling?

Optimal sample preparation is critical for successful ASIC3 antibody labeling across different applications:

Tissue preparation for immunohistochemistry:

• Fixation: Perfusion fixation with 4% paraformaldehyde is optimal for many ASIC3 antibodies .

• Sectioning: Optimal thickness is typically 10-20 μm for good antibody penetration.

• Storage: Store sections in cryoprotectant solution if not used immediately.

Sample processing protocol:

• Wash sections in PBS (3 times).

• Block with solution containing:

  • 10% normal horse serum (or appropriate species).

  • 1% Triton X-100 (for permeabilization).

  • PBS base.

• Incubate with primary ASIC3 antibody:

  • Typical dilutions: 1:200-1:400 for immunohistochemistry, 1:500 for Western blot .

  • Optimal incubation: Overnight at room temperature.

  • Diluent: PBS containing 0.3% Triton X-100 and 0.1% sodium azide .

• Wash thoroughly (3 times in PBS).

• Apply appropriate secondary antibody (2 hours at room temperature).

• Final washing and mounting.

Western blot sample preparation:

• Tissue lysis: Use RIPA buffer supplemented with protease inhibitors.

• Protein extraction from DRG: Requires careful homogenization.

• Protein quantification: Ensure equal loading.

• Sample denaturation: Heat at 95°C with reducing agent.

• Expected band size: 58 kDa for ASIC3 .

Multiple labeling considerations:

• For co-localization studies with markers like NF200, TrkA, CGRP, or TRPV1:

  • All primary antibodies can be diluted in the same incubation solution .

  • Choose primary antibodies raised in different species to avoid cross-reactivity.

  • Use highly cross-adsorbed secondary antibodies.

The ASIC3 antibody from Neuromics (#GP14105) has been validated to label ASIC3-transfected COS-7 cells, but not cells transfected with ASIC1a, 1b or 2 . Preabsorption with the immunizing peptide abolishes immuno-labeling in rat trigeminal ganglia and DRG . These protocols can be adapted based on the specific ASIC3 antibody being used and the experimental questions being addressed.

What approaches can be used to study ASIC3 channel kinetics?

Understanding ASIC3 channel kinetics requires specialized techniques that capture its unique gating properties and biphasic current profile:

Electrophysiological approaches:

• Whole-cell patch clamp:

  • Gold standard for studying ASIC3 current kinetics.

  • Measures activation, inactivation, and desensitization parameters.

  • Requires rapid solution exchange systems (<100 ms).

  • Can distinguish between fast transient and sustained current components .

• Outside-out patch recordings:

  • Provide faster solution exchange than whole-cell configuration.

  • Allow precise control of extracellular environment.

• Inside-out patch recordings:

  • Enable manipulation of intracellular factors that regulate ASIC3.

  • Study effects of intracellular pH, calcium, and signaling molecules.

Key kinetic parameters to measure:

• pH-dependent activation:

  • pH50 (pH producing half-maximal activation).

  • Hill coefficient (cooperativity of pH sensing).

  • Response onset time (time from pH change to current activation).

• Inactivation kinetics:

  • τinactivation (time constant of current decay).

  • Steady-state inactivation parameters.

  • Recovery from inactivation time course.

• Sustained current component:

  • Ratio of sustained/peak current.

  • pH-dependence of sustained current .

Pharmacological dissection of ASIC3 currents:

• Specific modulators:

  • APETx2: Selective ASIC3 antagonist .

  • GMQ: Non-proton ASIC3 agonist .

  • Amiloride: Non-selective ASIC blocker .

• Heteromeric channel properties:

  • Heteromeric channels have distinct kinetics.

  • Assembly with other ASIC subunits modulates channel properties .

Calcium imaging as an indirect measure:

• Load cells with ratiometric calcium indicators (e.g., Fura-2).

• Apply acidic solutions (pH 5.5-7.0) to activate ASIC3.

• Measure resulting calcium signals as an indirect readout of channel activation.

• This approach has been used to demonstrate ASIC3-dependent CGRP release in response to acidic stimulation .

These approaches provide complementary insights into ASIC3 channel kinetics, with the combination of electrophysiological recordings and calcium imaging offering comprehensive understanding of channel function across different conditions and in various cellular contexts.

How do ASIC3 antibodies help in studying pain mechanisms?

ASIC3 antibodies serve as crucial tools for investigating pain mechanisms through multiple approaches:

Visualizing ASIC3 expression patterns in pain pathways:

• Immunohistochemistry with ASIC3 antibodies allows researchers to map the distribution of this channel in dorsal root ganglia (DRG) and nociceptors involved in pain detection and transmission .

• This helps identify the neuronal populations that express ASIC3 and might contribute to specific pain modalities.

Identifying co-localization with other pain-related markers:

• Double or triple labeling techniques can reveal relationships between ASIC3 and other pain-related proteins like NF200 (myelinated neurons), TrkA (NGF-sensitive neurons), CGRP (peptidergic nociceptors), and TRPV1 (polymodal nociceptors) .

• Such co-localization studies help define the subpopulations of nociceptors that express ASIC3 and their potential functional specialization.

Assessing changes in ASIC3 expression during pathological conditions:

• ASIC3 antibodies can detect upregulation of ASIC3-immunoreactive nerves in inflammatory conditions, helping researchers understand how ASIC3 contributes to inflammatory pain .

• This approach has revealed increased ASIC3 expression in models of joint inflammation and skin inflammation.

Validating genetic manipulation models:

• ASIC3 antibodies are essential for confirming successful knockdown or knockout of ASIC3 in experimental models designed to study pain mechanisms .

• They provide validation of genetic approaches that aim to elucidate ASIC3's role in pain processing.

Correlating ASIC3 expression with functional outcomes:

• By combining immunohistochemical analysis with behavioral or electrophysiological assessments, researchers can link ASIC3 expression patterns to specific pain phenotypes.

• This has been demonstrated in studies showing that ASIC3 knockout mice display altered sensitivity to inflammatory pain .

Studies have demonstrated that ASIC3 plays significant roles in acidic, inflammatory, and postoperative pain, making ASIC3 antibodies valuable tools for pain research . The channel's role in detecting acidosis in damaged or inflamed tissue positions it as an important target for pain research and potential therapeutic intervention.

What are the best experimental protocols for studying ASIC3 in primary sensory neurons?

Comprehensive investigation of ASIC3 in primary sensory neurons requires a multi-faceted approach combining molecular, cellular, and functional techniques:

Isolation and culture of primary DRG neurons:

• Dissect DRGs from rodents (typically rats or mice).

• Enzymatically digest with collagenase and trypsin.

• Mechanically dissociate and plate on appropriate substrates.

• Culture in neurobasal medium supplemented with B27, glutamine, and nerve growth factor.

Immunocytochemical characterization:

• Fix cultures with 4% paraformaldehyde.

• Block with 10% normal horse serum and 1% Triton X-100.

• Incubate with anti-ASIC3 antibody (typical dilutions: 1:400-1:500) .

• Co-stain with markers for neuronal subpopulations:

  • NF200 for myelinated neurons.

  • TrkA for NGF-sensitive neurons.

  • CGRP for peptidergic nociceptors.

  • TRPV1 for polymodal nociceptors .

• Include appropriate controls (primary antibody omission, peptide competition) .

Functional assessment using calcium imaging:

• Load cultured neurons with calcium indicators.

• Apply acidic solutions (pH 5.5-7.0) to activate ASIC3.

• Test ASIC3-specific compounds:

  • GMQ as a non-proton agonist .

  • APETx2 as a selective antagonist .

  • Amiloride as a non-selective blocker .

• Quantify calcium responses and correlate with subsequent immunostaining.

Measurement of neuropeptide release:

• Stimulate DRG cultures with acidic solutions or ASIC3 agonists.

• Collect culture media at defined time points.

• Measure released neuropeptides (particularly CGRP) by enzyme immunoassay.

• Include appropriate controls with ASIC3 antagonists or in ASIC3-deficient cultures .

Genetic manipulation approaches:

• Use AAV vectors for efficient transduction of primary neurons.

• Target ASIC3 with specific shRNA.

• Validate knockdown with immunocytochemistry and functional assays .

• Compare with cultures from transgenic mice (ASIC3 knockout, conditional knockout).

These protocols provide complementary data on ASIC3 expression, localization, and function in primary sensory neurons, enabling comprehensive characterization of its role in nociception and inflammation. Recent studies demonstrating ASIC3's role in triggering CGRP release from sensory neurons in response to acidic stimulation highlight the value of these integrated approaches .

Future directions in ASIC3 antibody research

As our understanding of ASIC3's roles in pain and inflammation deepens, several promising directions for ASIC3 antibody research are emerging:

Development of conformation-specific antibodies:
Future research should focus on generating antibodies that can distinguish between different functional states of ASIC3 (closed, open, desensitized). Such tools would enable visualization of channel activation in situ and provide insights into the spatial and temporal dynamics of ASIC3 activation during pain and inflammation.

Improved subcellular localization:
Advanced imaging techniques combined with ASIC3 antibodies could reveal the subcellular distribution of these channels in sensory neurons, potentially identifying specialized microdomains that regulate ASIC3 function. Super-resolution microscopy approaches would be particularly valuable for this application.

Translational biomarker development:
ASIC3 expression patterns detected by antibodies could serve as biomarkers for inflammatory and neuropathic pain states. Correlating ASIC3 expression in accessible tissues with pain phenotypes could aid in diagnosis and treatment selection.

Therapeutic antibody development:
Function-blocking antibodies targeting the extracellular domain of ASIC3 represent a potential therapeutic approach for inflammatory pain conditions. The remarkable effect of ASIC3 deletion on psoriatic inflammation suggests that targeting this channel could have therapeutic benefits beyond pain relief .