klhl31 Antibody

What is KLHL31 and what is its primary function in skeletal muscle?

KLHL31 is a muscle-specific member of the Kelch-like protein family, primarily expressed in skeletal muscle tissue. It functions as a substrate-specific adaptor for Cullin3 (Cul3)-mediated protein degradation through the ubiquitin-proteasome system (UPS) . KLHL31 localizes predominantly to the Z-disc of the sarcomere and co-localizes with structural proteins like α-actinin and desmin . The protein plays a critical role in maintaining skeletal muscle structure and function by regulating the turnover of specific sarcomeric proteins, most notably Filamin-C (FlnC) . Loss of KLHL31 in knockout mouse models results in stunted postnatal skeletal muscle growth, centronuclear myopathy, sarcomeric disarray, and decreased muscle strength .

Methods for studying KLHL31 function typically involve:

• Immunofluorescence microscopy to determine subcellular localization

• Co-immunoprecipitation assays to identify interaction partners

• Ubiquitination assays to confirm substrate targeting

• Muscle strength and histological analyses in animal models

How is KLHL31 expression regulated during myogenic differentiation?

KLHL31 expression is regulated by the MEF2 (myocyte enhancer factor 2) family of transcription factors . The mouse Klhl31 promoter contains three MEF2 consensus-binding sites, with one conserved site approximately 500 bp upstream of the transcriptional start site . During development, Klhl31 expression increases after birth and is highly enriched in differentiated muscle tissue .

In experimental systems, Klhl31 expression increases during the differentiation of C2C12 myoblasts into myotubes, with both mRNA and protein levels rising as differentiation progresses . This expression pattern is slightly delayed compared to early myogenic regulatory factors, suggesting its role in later stages of myogenesis .

To study KLHL31 expression regulation:

• RT-PCR and Western blot analyses during myogenic differentiation

• Promoter-reporter assays using luciferase constructs

• ChIP assays to confirm MEF2 binding to the KLHL31 promoter

• RNA-seq analysis of differentiating muscle cells

What criteria should be used when selecting a KLHL31 antibody for muscle tissue research?

When selecting a KLHL31 antibody for muscle tissue research, consider these critical factors:

• Specificity: Validate using knockout tissues or cells as negative controls. Research has confirmed antibody specificity by showing absence of signal in Klhl31-KO myofibers .

• Host species: Choose based on your experimental design, especially if performing multi-color immunofluorescence. Avoid cross-reactivity with secondary antibodies.

• Application compatibility: Ensure the antibody is validated for your specific application (Western blot, immunofluorescence, immunoprecipitation).

• Epitope location: Consider if the epitope might be masked by protein interactions at the Z-disc.

• Species reactivity: Verify cross-reactivity if working with non-human models. KLHL31 sequences are conserved across mammals but verify for specific models.

Methodological approach for validation:

• Test on positive controls (skeletal muscle) and negative controls (non-muscle tissue or Klhl31-KO tissue)

• Perform peptide competition assays

• Compare results across multiple applications

• Consider monoclonal antibodies for highest specificity

How can researchers validate the specificity of a KLHL31 antibody?

Researchers should implement a multi-step validation strategy:

• Knockout/knockdown controls: The gold standard for validation is testing the antibody on tissues or cells lacking KLHL31 expression. Previous research validated antibody specificity by confirming absence of staining in isolated myofibers from Klhl31-KO mice .

• Overexpression systems: Test the antibody on cells transfected with tagged KLHL31 constructs. Previous validations demonstrated that only cells transfected with myc-KLHL31, identified by myc staining, were positive for KLHL31 antibody signals, confirming specificity .

• Multiple antibody comparison: Use antibodies raised against different epitopes of KLHL31 and compare their staining patterns.

• Western blot analysis: Confirm that the antibody detects a single band of the expected molecular weight (approximately 65 kDa for human KLHL31).

• Peptide blocking: Pre-incubate the antibody with the immunizing peptide to verify that staining is specifically blocked.

• Cross-reactivity tests: Ensure the antibody does not recognize similar Kelch-like family proteins by testing on cells overexpressing related proteins (e.g., KLHL40).

What are the optimal protocols for immunofluorescence staining of KLHL31 in muscle tissue sections?

For optimal immunofluorescence staining of KLHL31 in muscle tissue sections:

Fixation and Preparation:

• Use freshly frozen sections (8-10 μm) or paraformaldehyde-fixed (4%) sections

• For optimal Z-disc visualization, longitudinal sections are recommended

• Allow complete relaxation of muscle before fixation to maintain sarcomere structure

Staining Protocol:

• Permeabilize with 0.2-0.3% Triton X-100 for 10 minutes

• Block with 5% BSA/normal serum for 1 hour at room temperature

• Incubate with primary KLHL31 antibody overnight at 4°C (typically 1:200-1:500 dilution)

• Wash extensively with PBS (3-4 times, 5 minutes each)

• Incubate with fluorophore-conjugated secondary antibody for 1 hour at room temperature

• Counterstain with DAPI for nuclei visualization

• Mount with anti-fade mounting medium

Co-staining Recommendations:

• Co-stain with α-actinin to confirm Z-disc localization

• Co-stain with desmin to visualize cytoskeletal network associations

• For investigation of potential pathologies, combine with staining for Filamin-C

Troubleshooting:

• If signal is weak, try heat-mediated antigen retrieval

• Optimize antibody concentration specifically for your tissue type

• Test different fixatives if standard protocols yield poor results

How should researchers design co-immunoprecipitation experiments to study KLHL31 protein interactions?

For successful co-immunoprecipitation of KLHL31 and its interaction partners:

Lysate Preparation:

• Harvest muscle tissue or cultured myotubes in ice-cold conditions

• Lyse cells in a buffer containing:

  • 50 mM Tris-HCl (pH 7.4)

  • 150 mM NaCl

  • 1% NP-40 or Triton X-100

  • 1 mM EDTA

  • Protease inhibitor cocktail

  • Phosphatase inhibitors

  • 10 mM N-ethylmaleimide (to preserve ubiquitination)

• Homogenize tissue samples thoroughly using a Dounce homogenizer

• Centrifuge at 14,000g for 15 minutes at 4°C and collect supernatant

• Pre-clear lysate with protein A/G beads for 1 hour at 4°C

Immunoprecipitation Protocol:

• Incubate 500-1000 μg of pre-cleared lysate with 2-5 μg of KLHL31 antibody overnight at 4°C with gentle rotation

• Add 30-50 μl of protein A/G beads and incubate for 2-3 hours at 4°C

• Wash beads 4-5 times with lysis buffer containing reduced detergent (0.1%)

• Elute proteins by boiling in SDS sample buffer for 5 minutes

• Analyze by SDS-PAGE and immunoblot for potential interaction partners

Known Interaction Partners to Test:

• Cullin3 (Cul3): Confirmed strong interaction in previous studies

• Filamin-C (FlnC): Demonstrated interaction in transfected 293T cells

• Actin, Nebulin, CapZ, and tropomyosin: Potential interaction partners identified by yeast two-hybrid screening

Controls to Include:

• IgG control immunoprecipitation

• Input sample (5-10% of lysate used for IP)

• Reverse co-IP (immunoprecipitate the suspected partner and blot for KLHL31)

• Negative control using tissue/cells lacking KLHL31 expression

What methods are most effective for analyzing KLHL31's role in protein ubiquitination pathways?

To investigate KLHL31's function in protein ubiquitination:

Cellular Ubiquitination Assays:

• Transfect cells (e.g., HEK293T) with:

  • KLHL31 expression construct

  • Substrate protein construct (e.g., Filamin-C)

  • Cullin3 expression construct

  • HA or Flag-tagged ubiquitin construct

• Treat cells with proteasome inhibitor (e.g., MG132, 10 μM) for 4-6 hours before harvesting

• Lyse cells under denaturing conditions (1% SDS, boiling) to disrupt non-covalent interactions

• Dilute lysate and immunoprecipitate the substrate protein

• Immunoblot for ubiquitin to detect polyubiquitination

In Vitro Ubiquitination Assays:

• Purify recombinant KLHL31, Cul3, E1, E2 enzymes, and substrate protein

• Combine components with ubiquitin, ATP, and buffer in a test tube

• Incubate at 30°C for 1-2 hours

• Analyze reactions by SDS-PAGE and immunoblotting

Proteasomal Degradation Assays:

• Transfect cells with KLHL31 and substrate (e.g., FlnC)

• Treat cells with cycloheximide to inhibit new protein synthesis

• Harvest cells at different time points and analyze substrate protein levels

• Compare degradation rates with and without KLHL31 expression

• Include MG132 treatment controls to confirm proteasome-dependent degradation

Advanced Analysis Methods:

• Mass spectrometry to identify ubiquitination sites on substrates

• Ubiquitin chain topology analysis using ubiquitin mutants (K48R, K63R)

• Tandem affinity purification to identify novel KLHL31 substrates

Previous research demonstrated that FlnC expression was nearly ablated in the presence of KLHL31, Cul3, and wild-type ubiquitin, but remained stable with K48R mutant ubiquitin, confirming KLHL31's role in targeting FlnC for K48-linked polyubiquitination and proteasomal degradation .

How can KLHL31 antibodies be used to investigate pathological mechanisms in muscle disorders?

KLHL31 antibodies can provide valuable insights into muscle pathologies:

Centronuclear Myopathy and Central Core Disease:

• Use KLHL31 antibodies for immunohistochemical analysis of muscle biopsies to assess:

  • Z-disc integrity and sarcomeric organization

  • Accumulation of KLHL31 substrates like Filamin-C

  • Changes in KLHL31 expression or localization

• Compare patterns with those observed in Klhl31-KO mice, which exhibit:

  • Centronuclear myopathy

  • Central cores

  • Z-disc streaming

  • Sarcoplasmic reticulum dilation

Protein Aggregate Myopathies:

• Co-stain muscle biopsies for KLHL31 and Filamin-C to identify potential FlnC aggregates

• Investigate if KLHL31 colocalizes with protein aggregates in myofibrillar myopathies

• Analyze KLHL31 levels in conditions with known Z-disc protein accumulation

Research Methodology for Human Samples:

• Perform parallel Western blot and immunofluorescence analyses on patient biopsies

• Establish correlations between KLHL31 expression/localization and disease severity

• Create patient-derived myoblast cultures to study dynamic KLHL31 function in disease contexts

• Use laser capture microdissection to isolate regions of interest (e.g., central cores) for proteomic analysis

Animal Models and Cell Culture Applications:

• Use KLHL31 antibodies to validate muscle-specific knockout or transgenic mouse models

• Employ CRISPR/Cas9 genome editing in C2C12 cells to create Klhl31-mutant cell lines

• Analyze the effects of expressing disease-associated KLHL31 variants on sarcomere organization

What approaches can be used to study KLHL31 localization changes during myofibrillogenesis?

To investigate KLHL31 dynamics during myofibrillogenesis:

Time-Course Analysis in Differentiating C2C12 Cells:

• Induce C2C12 myoblast differentiation by switching to low-serum medium

• Fix cells at regular intervals (0, 24, 48, 72, 96 hours post-differentiation)

• Perform immunofluorescence for KLHL31 along with markers of different myofibrillogenesis stages:

  • Early (α-actinin, titin)

  • Intermediate (actin, tropomyosin)

  • Late (myosin heavy chain)

• Document changes in KLHL31 localization pattern from diffuse cytoplasmic to striated alignment

Live-Cell Imaging Approaches:

• Generate stable C2C12 lines expressing fluorescently-tagged KLHL31 (GFP-KLHL31 or KLHL31-DsRed)

• Use time-lapse confocal microscopy during differentiation

• Combine with fluorescently-tagged sarcomeric proteins to track co-localization in real-time

• Analyze trafficking of KLHL31 during stress fiber reorganization and sarcomere formation

Drug Perturbation Experiments:

Advanced Microscopy Techniques:

• Super-resolution microscopy (STORM, PALM) to precisely map KLHL31 position relative to Z-disc proteins

• FRAP (Fluorescence Recovery After Photobleaching) to analyze KLHL31 mobility and turnover at the Z-disc

• Correlative light-electron microscopy to relate KLHL31 localization to ultrastructural features

Troubleshooting and Data Interpretation

What are the promising research avenues for understanding KLHL31's role in muscle homeostasis and disease?

Several high-priority research directions deserve attention:

• Comprehensive substrate identification

  • Perform quantitative proteomics comparing wild-type and KLHL31-knockout muscles at different developmental stages

  • Use BioID or proximity labeling approaches to identify transient KLHL31 interaction partners

  • Develop systems to identify substrates that are rapidly degraded after KLHL31 interaction

• Disease-associated mutations

  • Screen for KLHL31 mutations in patients with unexplained centronuclear myopathy or Z-disc abnormalities

  • Create knock-in mouse models expressing disease-associated KLHL31 variants

  • Perform functional characterization of identified variants on substrate binding and degradation

• Regulatory mechanisms

  • Investigate post-translational modifications of KLHL31 that might regulate its activity

  • Study how mechanical stress and muscle contraction affect KLHL31 function

  • Explore potential autoregulation mechanisms suggested by KLHL31's ability to target itself for degradation

• Therapeutic implications

  • Test whether modulating KLHL31 activity can ameliorate pathologies associated with FlnC accumulation

  • Explore compensation by other Kelch-like family members in KLHL31-deficient muscle

  • Develop small molecules that could enhance KLHL31-mediated degradation of pathological protein aggregates

How can researchers effectively integrate KLHL31 antibody data with other research techniques to advance understanding of muscle biology?

Effective integration strategies include:

Multi-omics approaches:

• Combine KLHL31 antibody-based proteomics with transcriptomics to distinguish between transcriptional and post-transcriptional regulation

• Correlate KLHL31 localization data with spatial transcriptomics to identify region-specific functions

• Integrate ubiquitinome analysis with KLHL31 interactome data to prioritize direct substrates

Advanced imaging integration:

• Combine immunofluorescence data with electron microscopy to correlate KLHL31 localization with ultrastructural features

• Use live cell imaging of fluorescently tagged KLHL31 with force measurement techniques to study mechanosensitive regulation

• Apply quantitative image analysis to extract patterns from large datasets of KLHL31 staining in different muscle conditions

Functional validation strategies:

• Compare protein turnover rates in KLHL31-expressing vs. KLHL31-deficient systems using pulsed SILAC

• Correlate KLHL31 antibody staining patterns with functional measurements (force production, fatigue resistance)

• Develop muscle-on-chip systems to manipulate KLHL31 expression while monitoring contractile properties

Translational research integration:

• Establish biobanks of muscle biopsies with complete KLHL31 characterization

• Create patient-derived myoblast lines for personalized studies of KLHL31 function

• Develop standardized KLHL31 antibody-based assays for diagnostic use in myopathies