ccdc69 Antibody

What is CCDC69 and what cellular functions does it mediate?

CCDC69 is a 296-amino acid cytoplasmic protein (34.8 kDa canonical mass) that functions primarily as a scaffold to regulate recruitment and assembly of spindle midzone components during cell division. It is essential for proper localization of aurora B kinase (AURKB) and polo-like kinase 1 (PLK1) to the spindle midzone . CCDC69 plays a critical role in controlling central spindle assembly during anaphase and is implicated in cytokinesis progression in animal cells . Its expression is particularly high in the duodenum, esophagus, pancreas, prostate, salivary gland, thymus, and urinary bladder .

What are the key structural characteristics of CCDC69 protein that influence antibody selection?

CCDC69 contains coiled-coil domains that are critical for protein-protein interactions during spindle assembly. When selecting antibodies, researchers should consider epitopes that do not interfere with these functional domains if studying protein-protein interactions. Despite its calculated molecular weight of 34.8 kDa, CCDC69 typically migrates at 43-45 kDa on SDS-PAGE gels due to post-translational modifications or structural features affecting mobility . Antibodies raised against CCDC69 fusion proteins have demonstrated high specificity in detecting endogenous expression in human samples .

What experimental applications are CCDC69 antibodies commonly used for?

CCDC69 antibodies have been validated for multiple research applications including:

These applications allow researchers to detect CCDC69 expression, localization, and interactions in various experimental contexts .

How should researchers optimize Western blotting protocols for detecting CCDC69?

When performing Western blotting for CCDC69, researchers should consider several optimization steps. First, select antibodies that recognize the human CCDC69 protein specifically at the expected 43-45 kDa range rather than the theoretical 34.8 kDa size . For optimal results, use freshly prepared lysates from cells with documented CCDC69 expression (HeLa, U2OS, MDA-MB-231, and RT-4 cells have been validated) . Recommended dilutions range from 1:1000 to 1:8000, but titration within each testing system is advised for optimal signal-to-noise ratio . Consider using phosphate-buffered saline with 0.02% sodium azide and 50% glycerol (pH 7.3) as a storage buffer to maintain antibody stability during freeze-thaw cycles .

What methodological approaches are most effective for studying CCDC69 localization during mitosis?

For studying CCDC69 localization during mitosis, immunofluorescence microscopy with cell cycle synchronization is the preferred approach. Researchers should:

• Synchronize cells using double thymidine block or nocodazole treatment followed by release to enrich for mitotic cells

• Fix cells at specific time points following release to capture different mitotic phases

• Co-stain with antibodies against CCDC69 and established mitotic markers (tubulin, aurora B, PLK1)

• Use high-resolution confocal microscopy to visualize subcellular localization

Research indicates that endogenous CCDC69 localizes specifically to the central spindle during anaphase, making this a critical timepoint to capture . Live-cell imaging with fluorescently tagged CCDC69 can complement fixed-cell approaches but may affect protein function if the tag interferes with coiled-coil domains .

How does CCDC69 influence mitotic spindle formation and what experimental approaches best demonstrate this?

CCDC69 plays a crucial role in central spindle assembly during mitosis. Exogenous overexpression of CCDC69 in HeLa cells has been shown to interfere with microtubule polymerization and disrupt bipolar mitotic spindle formation . To experimentally demonstrate CCDC69's influence on spindle formation, researchers can:

• Perform RNAi-mediated knockdown of CCDC69 using targeted siRNAs or CRISPR/Cas9 gene editing

• Observe resulting aberrant central spindle formation through immunofluorescence

• Analyze the mislocalization of key midzone components such as aurora B kinase, PRC1, MgcRacGAP/HsCYK-4, and PLK1

• Quantify spindle defects and cytokinesis failures using time-lapse microscopy

Studies have demonstrated that CCDC69 may act as both a microtubule-destabilizing factor and a scaffold protein that controls central spindle assembly while recruiting midzone components to the central spindle .

What is the relationship between CCDC69 and G2/M cell cycle regulation in cancer cells?

CCDC69 functions as a critical G2/M cell cycle regulator in cancer cells by modulating key cell cycle proteins. Research on ovarian cancer cells has demonstrated that CCDC69 upregulates the expression level of Cdc2 (CDK1), a primary regulator of G2/M transition . When CCDC69 is knocked out in cisplatin-resistant ovarian cancer cells (A2780cis), treatment with cisplatin abrogates both G1 and G2/M arrest, indicating that CCDC69 plays a role in maintaining these cell cycle checkpoints .

Analysis of pathway interactions reveals that CCDC69 depletion affects p53/p21 signaling in chemoresistant cells. While total p53 expression remains relatively unchanged after cisplatin treatment in both wildtype and CCDC69 knockout cells, p21 upregulation is more pronounced in wildtype cells containing CCDC69, suggesting CCDC69 may influence p21 regulation through p53-independent mechanisms .

What role does CCDC69 play in chemoresistance mechanisms and how can antibodies be used to study this?

CCDC69 has been identified as a potential mediator of cisplatin resistance in ovarian cancer. Research has shown that CCDC69 expression is significantly upregulated (3-4 fold higher) in cisplatin-resistant A2780cis cells compared to cisplatin-sensitive A2780 parental cells . This upregulation appears to contribute to chemoresistance through several mechanisms:

• Regulation of cell cycle checkpoints (particularly G1 and G2/M arrest)

• Modulation of apoptotic pathways

• Influence on p53 acetylation and Bax mitochondrial redistribution

To study these mechanisms, CCDC69 antibodies can be employed in several experimental approaches:

• Western blotting to quantify CCDC69 expression levels between sensitive and resistant cell lines

• Immunoprecipitation to identify CCDC69 binding partners in the resistance pathway

• Immunofluorescence to determine subcellular localization changes during drug treatment

• ChIP assays to investigate potential roles in transcriptional regulation

Knockout studies using CRISPR/Cas9 have demonstrated that depletion of CCDC69 in cisplatin-resistant ovarian cancer cells resensitizes them to cisplatin treatment, as evidenced by decreased IC50 values and increased apoptotic markers .

How can researchers quantitatively assess CCDC69's impact on apoptotic pathways in cancer cells?

To quantitatively assess CCDC69's impact on apoptotic pathways, researchers should employ multiple complementary techniques:

• Annexin V/PI Flow Cytometry Analysis: Studies have shown significantly increased Annexin V-positive cells in CCDC69 knockout cells treated with cisplatin compared to wildtype cells (p<0.0001) .

• Mitochondrial Membrane Potential Assessment: Using JC-1 staining to measure mitochondrial transmembrane potential loss, which is more pronounced in CCDC69-depleted cells following cisplatin treatment .

• Caspase Activity Assays: Measuring activated caspase-3/7 and cleaved PARP by Western blotting, which show increased levels in CCDC69 knockout cells .

• Subcellular Fractionation: To detect Bax translocation to mitochondria, which is enhanced after CCDC69 depletion .

• Cell Cycle Analysis: Using PI staining and sub-G1 quantification to measure apoptotic cell populations .

Research has demonstrated that CCDC69 knockdown sensitizes resistant cancer cells to cisplatin by enhancing mitochondrial injury and activating both intrinsic and extrinsic apoptotic pathways, as evidenced by increased cleaved caspase-8 expression .

What are the key considerations for cross-species reactivity when selecting CCDC69 antibodies?

When selecting CCDC69 antibodies for cross-species applications, researchers should consider several factors:

For studies involving multiple species, researchers should select antibodies with documented cross-reactivity or validate untested antibodies through pilot experiments comparing known positive and negative tissues across target species.

What troubleshooting approaches should be considered when CCDC69 antibodies show unexpected molecular weight bands?

When encountering unexpected molecular weight bands with CCDC69 antibodies, researchers should consider several troubleshooting approaches:

• Understand expected migration patterns: The canonical molecular weight of CCDC69 is 34.8 kDa, but it typically migrates at 43-45 kDa in SDS-PAGE due to post-translational modifications or structural features .

• Verify specificity through knockout controls: Generate CCDC69 knockout cells using CRISPR/Cas9 (as demonstrated in A2780cis CCDC69-/- #26 and SKOV3 CCDC69-/- #9 cells) to confirm band specificity .

• Assess potential isoforms: Check genomic databases for alternative splicing variants that might explain additional bands.

• Evaluate post-translational modifications: Phosphorylation, ubiquitination, or other modifications can alter migration patterns.

• Examine sample preparation effects: Proteolytic degradation during sample preparation may generate fragments with unexpected sizes.

• Test multiple antibodies: Compare results with antibodies targeting different epitopes to build confidence in band identification.

If multiple bands persist, researchers can perform immunoprecipitation followed by mass spectrometry to definitively identify the CCDC69 protein and its potential modifications or interacting partners.

What experimental designs best elucidate the interaction between CCDC69 and mitotic kinases?

To effectively study interactions between CCDC69 and mitotic kinases like aurora B and PLK1, researchers should employ multiple complementary approaches:

• Co-immunoprecipitation (Co-IP): Using CCDC69 antibodies to pull down protein complexes, followed by Western blotting for aurora B or PLK1. This approach has demonstrated physical interactions between CCDC69 and aurora B .

• Proximity Ligation Assay (PLA): This technique can visualize and quantify protein-protein interactions in situ with high sensitivity and specificity.

• Fluorescence Resonance Energy Transfer (FRET): By tagging CCDC69 and candidate kinases with appropriate fluorophores, researchers can measure direct interactions in living cells.

• Bimolecular Fluorescence Complementation (BiFC): This approach allows visualization of protein interactions through complementary fluorescent protein fragments.

• In vitro kinase assays: To determine if CCDC69 is a substrate for mitotic kinases, purified proteins can be used in phosphorylation assays.

Research has established that CCDC69 localizes to the central spindle and physically interacts with aurora B. CCDC69 depletion delocalizes aurora B (a component of the chromosomal passenger complex), along with other midzone components like MgcRacGAP and PRC1 .

How can epigenetic regulation of CCDC69 be studied in the context of cancer therapy resistance?

To investigate epigenetic regulation of CCDC69 in cancer therapy resistance, researchers should consider the following methodological approaches:

• Bisulfite Sequencing: This technique has revealed heavy CpG methylation (73.1% and 74.3%) in the CCDC69 promoter region in A2780 and A2780cis ovarian cancer cells .

• 5-Aza-dC Treatment Studies: Treatment with the DNA methyltransferase inhibitor 5-Aza-dC restored CCDC69 expression in both A2780 and A2780cis cells, indicating epigenetic silencing .

• ChIP-Seq Analysis: To identify transcription factors and histone modifications associated with CCDC69 regulation during resistance development.

• RNA-Seq After Epigenetic Modifier Treatment: To examine global expression changes following demethylation and how CCDC69 fits into broader resistance pathways.

• CRISPR-dCas9 Epigenetic Editing: This approach can be used to specifically modify epigenetic marks at the CCDC69 locus to establish causality.

Research suggests complex epigenetic regulation of CCDC69, as cisplatin-resistant A2780cis cells show higher CCDC69 expression despite similar methylation levels as cisplatin-sensitive A2780 cells, pointing to additional regulatory mechanisms beyond DNA methylation .