CCDC28A Antibody

What is CCDC28A and why is it relevant to reproductive biology research?

CCDC28A is a coiled-coil domain-containing protein 28A that plays a critical role in male reproductive biology. It is specifically expressed in male germ cells and is essential for proper sperm tail morphogenesis and function. Research has demonstrated that CCDC28A deficiency results in diminished sperm motility and structural aberrations in sperm tails, particularly affecting the head-tail coupling apparatus (HTCA) . Understanding this protein is crucial for researchers investigating male infertility, as CCDC28A knockout models show disruptions at the capitulum-basal plate junction of the HTCA, leading to bending of the sperm head within the neck region and thickening of the tail midpiece .

How does CCDC28A differ structurally and functionally from its paralog CCDC28B?

While CCDC28A and CCDC28B share approximately 50% amino acid identity and both contain coiled-coil domains, they exhibit distinctive expression patterns and functional roles. CCDC28A is primarily expressed in germ cells, whereas CCDC28B is expressed in supporting somatic cells within the testes . Additionally, CCDC28B has been implicated in ciliogenesis and co-localizes with Bardet-Biedl syndrome proteins at peri-centriolar structures, with mutations contributing epistatic alleles to Bardet-Biedl syndrome, an oligogenic disease associated with basal bodies and cilia disorders . When designing antibodies and experiments, researchers must account for these structural similarities to avoid cross-reactivity while targeting the unique functional domains of each protein.

What are the key structural features of human CCDC28A protein that antibodies might target?

Human CCDC28A encodes two potential protein isoforms with distinct structural characteristics:

• Long (L) isoform: 274 amino acids with an extended N-terminus containing a globular domain (~1/3 strong hydrophobic amino acids)

• Short (S) isoform: 184 amino acids, well-conserved across species

The most conserved region includes an approximately 100 amino acid-long predicted coiled-coil (CC) motif . This region shows 93% amino acid identity with the murine protein (NP_659069). When developing antibodies, researchers should consider whether to target:

• Common epitopes (present in both isoforms, typically in the CC domain)

• Isoform-specific epitopes (particularly the N-terminal 90 amino acids unique to the L-isoform)

• Species-conserved epitopes (for cross-species research applications)

What is the expression profile of CCDC28A across different cell types and tissues?

CCDC28A shows differential expression across various cell types, with particular enrichment patterns relevant to research:

This expression profile should inform research design, including selection of appropriate positive and negative control tissues when validating CCDC28A antibodies .

What criteria should be used when selecting or generating CCDC28A antibodies for specific research applications?

When selecting CCDC28A antibodies, researchers should consider:

• Target specificity: Determine whether you need to detect both isoforms or discriminate between them

• Cross-reactivity: Assess potential cross-reactivity with CCDC28B due to 50% sequence homology

• Application compatibility: Verify antibody suitability for your specific applications (Western blot, immunohistochemistry, flow cytometry, etc.)

• Epitope location: For studying protein interactions, avoid antibodies targeting functional domains that might interfere with binding partners

• Species reactivity: Select antibodies with appropriate cross-reactivity if conducting comparative studies

For maximum specificity in distinguishing CCDC28A from CCDC28B, target antibodies to the less conserved regions outside the coiled-coil domain, particularly when investigating reproductive biology contexts where both proteins are present but in different cell types .

What validation methods are essential for confirming CCDC28A antibody specificity?

Rigorous validation of CCDC28A antibodies should include:

• Western blot analysis using:

  • Positive controls (tissues with known expression: testes, hematopoietic stem cells)

  • Negative controls (tissues with minimal expression)

  • Recombinant CCDC28A (both isoforms if possible)

  • CCDC28A knockout samples (when available)

• Peptide competition assays to confirm binding specificity

• Immunoprecipitation followed by mass spectrometry to verify target identity

• Immunohistochemistry validation comparing expression patterns with in situ hybridization data

• Cross-reactivity testing against CCDC28B to ensure specificity

Researchers should be particularly cautious about potential cross-reactivity given the structural similarity between CCDC28A and CCDC28B, and the existence of multiple isoforms .

How can CCDC28A antibodies be effectively used to study head-tail coupling defects in sperm?

To investigate CCDC28A's role in sperm head-tail coupling:

• Immunofluorescence microscopy:

  • Use CCDC28A antibodies to visualize protein localization at the HTCA

  • Co-stain with markers for the capitulum and basal plate

  • Compare normal and abnormal sperm morphology

• Transmission electron microscopy (TEM) with immunogold labeling:

  • Apply CCDC28A antibodies conjugated to gold particles

  • Analyze the precise subcellular localization within the HTCA

  • Identify structural abnormalities at the capitulum-basal plate junction

• Comparative analysis workflow:

  • Collect sperm samples from control and CCDC28A-deficient models

  • Quantify morphological defects using standardized criteria

  • Correlate CCDC28A expression levels with severity of HTCA disruption

  • Assess the relationship between structural abnormalities and motility parameters

This multifaceted approach enables researchers to establish the mechanistic link between CCDC28A deficiency and the observed bending of the head within the neck region, often accompanied by thickening of the tail midpiece .

What are the optimal fixation and processing protocols for CCDC28A immunohistochemistry in testicular tissue?

For optimal CCDC28A detection in testicular tissue:

• Fixation options:

  • For paraffin sections: 4% paraformaldehyde (12-24 hours) preserves both morphology and antigenicity

  • For frozen sections: 2% paraformaldehyde (2 hours) followed by sucrose cryoprotection

• Antigen retrieval:

  • Heat-induced epitope retrieval in citrate buffer (pH 6.0)

  • For coiled-coil domains, consider additional treatment with 0.5% Triton X-100

• Blocking protocol:

  • 5% normal serum (from species of secondary antibody)

  • 1% BSA in PBS

  • Include 0.3% glycine to reduce background

• Antibody incubation:

  • Primary antibody dilution should be empirically determined (typically 1:100-1:500)

  • Overnight incubation at 4°C for maximum sensitivity

  • Include controls: CCDC28B antibody (to verify differential cell type expression)

• Detection system:

  • Fluorescent: Alexa Fluor-conjugated secondary antibodies for multicolor analysis

  • Chromogenic: HRP/DAB for archival samples and quantitative analysis

These protocols should allow clear visualization of CCDC28A in male germ cells while maintaining the ability to distinguish from CCDC28B expression in somatic cells .

How can CCDC28A antibodies contribute to understanding leukemia pathogenesis?

CCDC28A antibodies provide valuable tools for investigating leukemia mechanisms:

• Detection of NUP98-CCDC28A fusion protein:

  • Western blot analysis to identify the chimeric protein in patient samples

  • Immunoprecipitation to isolate and characterize fusion protein complexes

  • Antibodies targeting different domains can distinguish between normal CCDC28A and fusion protein

• Expression profiling across leukemia subtypes:

  • Immunohistochemistry to evaluate CCDC28A expression in different FAB classifications

  • Flow cytometry to quantify expression levels in specific cell populations

  • Correlate expression with clinical outcomes and molecular subtypes

• Mechanistic studies:

  • ChIP assays to identify genomic binding sites of NUP98-CCDC28A

  • Co-immunoprecipitation to isolate interacting partners

  • Analysis of downstream pathways affected by fusion protein expression

Research has revealed that CCDC28A is selectively enriched in the FAB-M6 class of acute myeloid leukemia and in T-ALL samples associated with MLL internal duplications, suggesting specific pathological roles in these contexts .

What methodological considerations are important when using CCDC28A antibodies in flow cytometry for hematopoietic stem cell research?

When employing CCDC28A antibodies for flow cytometry in hematopoietic research:

• Cell preparation considerations:

  • Fixation: 2% paraformaldehyde followed by permeabilization with 0.1% saponin

  • For detecting nuclear or perinuclear antigens, use methanol permeabilization

• Antibody panel design:

  • Include established stem cell markers (c-Kit, Sca1) for co-expression analysis

  • Incorporate lineage markers (Mac1/CD11b, Gr1, B220, CD19, CD8, CD4, Ter119, CD41)

  • Use fluorophores with minimal spectral overlap for CCDC28A detection

• Controls and validation:

  • Include fluorescence minus one (FMO) controls

  • Use CCDC28A-overexpressing and knockout samples as positive and negative controls

  • Block with recombinant CCDC28A protein to confirm specificity

• Sorting strategies for downstream applications:

  • Sort cells based on CCDC28A expression levels

  • Perform functional assays to correlate expression with stem cell properties

  • Analyze sorted populations by qPCR to confirm CCDC28A transcript levels

This methodology leverages the enriched expression of CCDC28A in hematopoietic stem cells, common lymphoid progenitors, and naive T and NK cells to advance our understanding of its role in normal hematopoiesis and leukemic transformation .

How can researchers distinguish between the long and short isoforms of CCDC28A in experimental systems?

To effectively differentiate between CCDC28A isoforms:

• Isoform-specific antibody approach:

  • Generate antibodies targeting the N-terminal 90 amino acids unique to the L-isoform

  • Use common region antibodies to detect total CCDC28A expression

  • Apply both antibodies in parallel experiments to determine relative isoform abundance

• Western blot optimization:

  • Use high-resolution SDS-PAGE (12-15%) to separate the 274aa (L) and 184aa (S) isoforms

  • Include recombinant proteins of both isoforms as size references

  • Employ gradient gels for improved separation of closely migrating bands

• Mass spectrometry analysis:

  • Immunoprecipitate CCDC28A from tissue samples

  • Perform tryptic digestion and analyze peptide fragments

  • Identify isoform-specific peptides from the N-terminal region

• RNA-based approaches as complementary methods:

  • Design primers spanning the translation start sites of both isoforms

  • Perform qRT-PCR with isoform-specific primers

  • Use RNA-seq data to quantify relative isoform expression levels

This multi-faceted approach helps researchers accurately characterize the expression patterns of CCDC28A isoforms across different tissues and experimental conditions, which is particularly relevant given their potential distinct functions .

What approaches can be used to investigate interactions between CCDC28A and other proteins in the head-tail coupling apparatus?

To investigate CCDC28A protein interactions in the HTCA:

• Co-immunoprecipitation strategies:

  • Use CCDC28A antibodies to pull down protein complexes from testicular lysates

  • Analyze by mass spectrometry to identify novel interacting partners

  • Confirm interactions with reciprocal co-IP using antibodies against identified partners

• Proximity ligation assay (PLA):

  • Apply CCDC28A antibodies together with antibodies against suspected interaction partners

  • Visualize and quantify interactions in situ within specific subcellular compartments

  • Compare interaction patterns between normal and pathological samples

• Yeast two-hybrid screening:

  • Use CCDC28A domains (particularly the coiled-coil region) as bait

  • Screen testis-specific cDNA libraries to identify potential binding partners

  • Validate candidates using biochemical and cellular approaches

• FRET/FLIM analysis:

  • Express fluorescently-tagged CCDC28A with potential partners

  • Measure energy transfer to confirm direct protein-protein interactions

  • Map interaction domains through deletion constructs

Understanding these interactions will provide mechanistic insights into how CCDC28A deficiency leads to the observed structural aberrations in sperm tails and the resulting male infertility .

How can researchers address potential cross-reactivity between CCDC28A and CCDC28B antibodies?

To mitigate CCDC28A/CCDC28B cross-reactivity issues:

• Epitope selection strategy:

  • Target the least conserved regions between the two proteins

  • Avoid antibodies directed against the highly conserved coiled-coil domains

  • Consider using peptide antibodies against unique sequences

• Pre-absorption protocol:

  • Incubate antibodies with recombinant CCDC28B protein prior to use

  • Titrate the amount of blocking protein to maintain CCDC28A sensitivity

  • Perform parallel experiments with non-absorbed antibody to assess specificity gain

• Validation using genetic models:

  • Test antibodies on CCDC28A and CCDC28B knockout tissues

  • Create expression systems with tagged versions of each protein

  • Compare reactivity patterns with mRNA expression data

• Differential expression analysis:

  • Exploit the distinct cellular expression patterns (CCDC28A in germ cells, CCDC28B in somatic cells)

  • Use co-localization with cell-type specific markers

  • Employ dual immunofluorescence with validated antibodies for each protein

This methodical approach helps ensure experimental observations are attributed to the correct protein, particularly in tissues where both paralogs are expressed .

What are the critical controls for interpreting CCDC28A antibody results in leukemia research?

For robust interpretation of CCDC28A antibody data in leukemia studies:

• Essential positive controls:

  • FAB-M6 leukemia samples (known to have enriched CCDC28A expression)

  • T-ALL samples with MLL internal duplications

  • Tissues with confirmed high CCDC28A expression (testis, hematopoietic stem cells)

• Negative controls:

  • CCDC28A-knockdown cell lines

  • Non-hematopoietic tissues with minimal CCDC28A expression

  • Isotype control antibodies to assess non-specific binding

• Technical validation controls:

  • Peptide competition assays to confirm specificity

  • Multiple antibodies targeting different epitopes

  • Correlation with mRNA expression data

• Context-specific controls:

  • For NUP98-CCDC28A fusion studies, include controls for NUP98 expression

  • When assessing fusion protein function, include NUP98 fusion proteins with other partners

  • Compare with other fusion proteins that do not involve the Hoxa-Meis1 pathway

• Functional readouts:

  • Correlate antibody staining with proliferative capacity

  • Assess relationship between CCDC28A detection and self-renewal potential of myeloid progenitors

  • Compare results with known leukemogenic pathways

These controls help researchers interpret CCDC28A antibody results within the complex context of leukemia heterogeneity and ensure findings are specific and reproducible .