cep83 Antibody

What is CEP83 and why is it significant in cellular research?

CEP83 (Centrosomal Protein 83kDa), also known as CCDC41 (coiled-coil domain containing 41), is a 701-residue protein primarily composed of coiled-coil domains that functions as a key component of centriolar distal appendages (DAPs). It plays a crucial role in primary ciliogenesis by facilitating ciliary vesicle docking to the mother centriole. CEP83 is required for the recruitment of other DAP components, including its partner CEP164/NPHP15, to the mother centriole. Research significance extends to developmental biology and disease mechanisms, as mutations in CEP83 have been linked to infantile nephronophthisis, making it an important target for studying ciliopathies . Additionally, CEP83 may collaborate with IFT20 in trafficking ciliary membrane proteins from the Golgi complex to the cilium during primary cilia initiation .

What applications are validated for CEP83 antibody use?

CEP83 antibodies have been validated for multiple research applications:

The antibody shows strong reactivity with human samples and has been cited for reactivity with mouse samples as well . For optimal immunohistochemistry results with human kidney tissue, antigen retrieval with TE buffer pH 9.0 is suggested, with citrate buffer pH 6.0 as an alternative .

What cellular structures does CEP83 localize to?

CEP83 predominantly localizes to centriolar distal appendages (DAPs) of the mother centriole, where it forms a ring-shaped structure. In retinal pigment epithelial (RPE1) cells and primary human skin fibroblasts, CEP83 colocalizes with CEP164 at DAPs and shows a predominant staining pattern on one of the two centrioles (the mother centriole). Additionally, CEP83 has been observed at the Golgi apparatus, suggesting its potential role in vesicular trafficking processes . This localization pattern is consistent with its function in early ciliogenesis, where it facilitates the docking of the mother centriole to primary ciliary vesicles .

How should CEP83 antibody samples be stored for optimal results?

For optimal long-term stability and activity, CEP83 antibody should be stored at -20°C. The antibody remains stable for one year after shipment when properly stored. The standard formulation includes PBS with 0.02% sodium azide and 50% glycerol at pH 7.3. Importantly, aliquoting is not necessary for -20°C storage of standard antibody preparations. For certain preparations (20μl sizes), the solution contains 0.1% BSA as a stabilizer . When working with the antibody, avoid repeated freeze-thaw cycles as these can compromise antibody performance and potentially lead to increased background in experimental applications.

What are the recommended positive controls for CEP83 antibody validation?

For reliable experimental design and antibody validation, researchers should consider the following positive controls that have been experimentally validated:

These controls have been specifically tested and verified to express detectable levels of CEP83, making them suitable for antibody validation experiments . Using these established controls helps ensure experimental reliability and facilitates troubleshooting if problems arise during protocol optimization.

How can I detect phosphorylated forms of CEP83?

Detecting phosphorylated CEP83 requires specific considerations as recent research has identified that CEP83 is phosphorylated by Tau-tubulin kinase-2 (TTBK2) at four specific sites: Ser29, Thr292, Thr527, and Ser698 . To effectively detect phosphorylated CEP83:

• Use phospho-specific antibodies: Specialized antibodies targeting phospho-CEP83 at Ser29 and Thr292 have been developed and validated through peptide competition assays .

• For 2D gel electrophoresis: Phosphorylated CEP83 can be distinguished by charge separation, where phosphorylated forms show characteristic spot patterns that shift upon alkaline phosphatase treatment .

• Experimental timing: Significant CEP83 phosphorylation is observed following serum starvation, which induces ciliogenesis. Comparing proliferating versus serum-starved cells can highlight phosphorylation changes .

• Controls: Include TTBK2 knockout cells as negative controls, as these cells show impaired CEP83 phosphorylation upon serum starvation .

The phosphorylation status of CEP83 is functionally significant, particularly during cilia initiation, making these detection methods valuable for studying ciliary dynamics.

What is the relationship between TTBK2 and CEP83 in ciliogenesis research?

TTBK2 (Tau-tubulin kinase-2) has been identified as a critical kinase that phosphorylates CEP83 during cilia initiation. This relationship presents several important research considerations:

• Recruitment mechanism: TTBK2 is recruited to the centriole by the distal appendage protein CEP164, creating a sequential molecular pathway (CEP164→TTBK2→CEP83) .

• Phosphorylation sites: TTBK2 specifically phosphorylates CEP83 at four sites: Ser29, Thr292, Thr527, and Ser698, which can be confirmed through mass spectrometry analysis .

• Functional significance: TTBK2-mediated phosphorylation of CEP83 is crucial for early ciliogenesis steps, particularly ciliary vesicle docking and CP110 removal .

• Experimental validation: Both in vivo and in vitro kinase assays confirm that CEP83 is a direct substrate of TTBK2, with phosphorylation dependent on TTBK2's catalytic activity .

• Serum starvation effects: Upon serum starvation, TTBK2 redistributes from the periphery toward the root of distal appendages, coinciding with increased CEP83 phosphorylation .

This kinase-substrate relationship provides a molecular mechanism linking TTBK2 (which is genetically associated with spinocerebellar ataxia type 11) to ciliogenesis through CEP83 phosphorylation.

How do CEP83 mutations affect its detection and function?

Research on CEP83 mutations provides important insights for experimental design and interpretation:

Most reported mutations in CEP83 affect its coiled-coil domains or highly conserved residues. These mutations can significantly impact protein detection and function in several ways:

• Detection challenges: Truncating mutations (e.g., p.Gln81* and p.Cys510*) result in truncated proteins that may not be detected by antibodies targeting C-terminal epitopes .

• Centrosomal localization: In cells from affected individuals with CEP83 mutations, CEP83 staining appears fainter and dispersed around centrioles compared to control cells .

• Partner protein recruitment: CEP83 mutations impair the protein's ability to recruit its partner CEP164 to the centrosome, disrupting the normal ring-shaped organization of CEP164 .

• Protein stability: Immunoblotting in cells from affected individuals shows reduced CEP83 levels, indicating possible protein stability issues .

• Domain-specific effects: C-terminal variants (p.Arg511Pro, p.Glu669Aspfs*14, and p.Gln692del) show impaired ability to interact with CEP164, while proteins with N-terminal variants (p.Leu87Pro and p.Pro112_Leu117del) maintain this interaction .

These findings have implications for designing experiments involving CEP83 and interpreting results when studying ciliopathies.

What experimental approaches can assess CEP83 protein interactions?

To study CEP83 interactions with partner proteins, several validated approaches have been documented:

• Co-immunoprecipitation: This technique has successfully demonstrated CEP83 interactions with CEP164 and IFT20. For example, CEP164-myc and IFT20-GFP were efficiently co-immunoprecipitated with FLAG-CEP83 WT in NIH 3T3 cells, confirming complex formation .

• Domain mutation analysis: Generating CEP83 variants with specific mutations and testing their ability to interact with partner proteins can map interaction domains. C-terminal CEP83 variants showed impaired ability to interact with CEP164, while N-terminal variants maintained this interaction .

• Fluorescence microscopy: Colocalization studies using superresolution microscopy can reveal spatial relationships between CEP83 and its partners. CEP83 colocalizes with CEP164 at distal appendages in a characteristic ring-shaped distribution .

• Dominant-negative approaches: Overexpression of wild-type CEP83 in cells causes a dominant-negative effect on the recruitment of endogenous CEP164 to the centrosome, providing an experimental tool to study functional relationships .

• Proximity ligation assays: Although not explicitly mentioned in the provided search results, this technique would be appropriate for confirming protein interactions in situ.

These approaches provide complementary information about CEP83's interaction network and functional relationships with distal appendage components.

What strategies can detect CEP83's role in ciliopathies?

CEP83 mutations have been linked to infantile nephronophthisis, providing valuable insights for studying ciliopathies:

• Tissue-specific analysis: Examining CEP83 and CEP164 localization in kidney biopsies from control and affected individuals. In control kidneys, both proteins localize to one of the two centrioles, while in affected individuals, CEP83 staining appears fainter and CEP164 may be absent from some centrosomes .

• Quantitative assessment: Measuring the percentage of CEP164-positive centrosomes (e.g., 50.1% in affected individuals versus 83.6% in controls) provides a quantitative readout of DAP defects .

• Functional rescue experiments: Testing whether wild-type CEP83 can rescue the phenotypes observed in cells from affected individuals can confirm causality.

• Structural analyses: Analyzing how specific mutations (like deletion of single amino acids p.Glu684del and p.Gln692del or introduction of proline residues p.Leu87Pro and p.Arg511Pro) affect coiled-coil domain organization provides mechanistic insights .

• Cell models: Using patient-derived fibroblasts or kidney cells provides relevant cellular contexts for studying disease mechanisms related to CEP83 dysfunction .

These approaches bridge basic research on CEP83 with clinical manifestations of ciliopathies, demonstrating the translational relevance of CEP83 studies.

Why might CEP83 antibody staining appear inconsistent between experiments?

Inconsistent CEP83 staining can result from several factors that researchers should consider:

• Cell cycle-dependent localization: CEP83 predominantly localizes to the mother centriole's distal appendages, which undergo remodeling throughout the cell cycle. Synchronizing cells or noting their cell cycle stage is crucial for consistent results .

• Antibody specificity: Different antibodies recognize distinct epitopes of CEP83. If using antibodies targeting the C-terminus, truncated variants may go undetected .

• Fixation sensitivity: CEP83 epitopes may be sensitive to specific fixation conditions. For IHC applications, antigen retrieval with TE buffer pH 9.0 is recommended, with citrate buffer pH 6.0 as an alternative .

• Phosphorylation status: TTBK2-mediated phosphorylation of CEP83 (at Ser29, Thr292, Thr527, and Ser698) changes during ciliogenesis. Serum starvation induces CEP83 phosphorylation, which could affect epitope accessibility .

• Overexpression artifacts: Transfection of wild-type CEP83 can result in dominant-negative effects on endogenous CEP164 recruitment to the centrosome, potentially complicating interpretation of overexpression studies .

Understanding these factors can help researchers troubleshoot inconsistent staining patterns and design more reliable experiments.

What molecular weights should I expect for CEP83 in Western blots?

When performing Western blot analysis for CEP83, researchers should be aware of specific molecular weight expectations:

The presence of two bands (83 kDa and 68 kDa) is a normal observation for CEP83 . This pattern may result from:

• Post-translational modifications: Phosphorylation by TTBK2 at four sites (Ser29, Thr292, Thr527, and Ser698) can alter the apparent molecular weight .

• Alternative splicing: Though not explicitly mentioned in the provided search results, this is a common cause of multiple bands.

• Proteolytic processing: Partial degradation or physiological processing can generate fragments.

• Different isoforms: CEP83 may exist in different isoforms in various cell types.

If unexpected banding patterns occur, researchers should validate specificity through knockdown/knockout controls or blocking peptides to ensure the bands represent genuine CEP83 protein.

How can I optimize double immunofluorescence labeling with CEP83 antibody?

For successful double immunofluorescence labeling involving CEP83:

• Antibody compatibility: When co-staining CEP83 with other centrosomal markers, consider species compatibility. The CEP83 antibody (26013-1-AP) is a rabbit polyclonal, so partner antibodies should be from different species (e.g., mouse, goat) to avoid cross-reactivity .

• Sequential staining: For challenging combinations, consider sequential rather than simultaneous immunostaining protocols.

• Validated marker combinations: Several successful co-staining combinations have been documented:

  • CEP83 with centrin or γ-tubulin for basic centrosome labeling

  • CEP83 with CEP164 for distal appendage co-localization studies

  • CEP83 with ODF2 for subdistal appendage differentiation

• Dilution optimization: For immunofluorescence applications, a dilution range of 1:200-1:800 is recommended for CEP83 antibody, but this should be optimized for each specific application and cell type .

• Fixation method: For optimal preservation of centrosomal structures, methanol fixation often yields better results than formaldehyde for centriolar proteins, though specific protocols should be tested empirically.

Following these guidelines can help achieve clear co-localization results when studying CEP83 in relation to other centrosomal components.

What controls are essential when studying CEP83 phosphorylation?

To rigorously study CEP83 phosphorylation, several critical controls should be implemented:

• Phosphatase treatment: Treating samples with alkaline phosphatase before analysis serves as a negative control. In 2D gel electrophoresis, this treatment causes a characteristic right-shifting of CEP83 spots, confirming phosphorylation status .

• TTBK2 knockout cells: Since TTBK2 is the kinase responsible for CEP83 phosphorylation, TTBK2 knockout cells provide an excellent negative control. In these cells, serum starvation fails to induce CEP83 phosphorylation .

• Phospho-mutant comparison: The CEP83-4A mutant (with Ser29, Thr292, Thr527, and Ser698 mutated to alanine) serves as a non-phosphorylatable control. This mutant shows no phosphorylation even when TTBK2 is overexpressed .

• Proliferating versus serum-starved conditions: Comparing these conditions provides a physiological context, as CEP83 phosphorylation increases upon serum starvation-induced ciliogenesis .

• Phospho-specific antibodies validation: When using phospho-specific antibodies (e.g., anti-phospho-CEP83 Ser29 and anti-phospho-CEP83 Thr292), peptide competition assays should be performed to confirm specificity .

These controls ensure reliable interpretation of CEP83 phosphorylation data in both basic research and disease-related studies.

How can I design experiments to study CEP83's role in ciliogenesis?

To effectively investigate CEP83's function in ciliogenesis, consider these experimental design strategies:

• Knockdown/knockout approaches: Depleting CEP83 affects early steps of ciliogenesis by preventing docking of the mother centriole to the primary ciliary vesicle. This provides a model to study its necessity in the ciliation process .

• Phosphorylation studies: Since TTBK2-dependent CEP83 phosphorylation is important for cilia initiation, comparing wild-type CEP83 with phospho-mutants (CEP83-4A) can reveal how phosphorylation affects ciliogenesis steps .

• Superresolution microscopy: This technique has revealed that serum starvation induces TTBK2 redistribution from the periphery toward the root of distal appendages, coinciding with CEP83 phosphorylation. Similar approaches can track CEP83 dynamics during ciliogenesis .

• Ciliary vesicle docking assays: Since CEP83 is required for docking of the mother centriole to the primary ciliary vesicle, assays monitoring this process can provide functional readouts .

• CP110 removal monitoring: One of the early steps in ciliogenesis is CP110 removal, which is influenced by CEP83 function. Tracking CP110 can serve as a readout for proper CEP83 function .

• Partner protein recruitment analysis: Measuring CEP164 recruitment to the centrosome serves as a functional readout of CEP83 activity, as CEP83 is required for CEP164 localization to distal appendages .

These approaches provide complementary insights into CEP83's multifaceted roles in ciliogenesis.

What cell types are optimal for studying CEP83 function?

Different cell types offer specific advantages for CEP83 research:

The choice of cell type should align with specific research questions, with RPE1 cells being particularly valuable for basic ciliogenesis research due to their robust and synchronizable ciliation response to serum starvation.

How can dominant-negative approaches enhance CEP83 functional studies?

Dominant-negative approaches provide powerful tools for dissecting CEP83 function:

Research has shown that transfection of wild-type CEP83 results in a dominant-negative effect on the recruitment of endogenous CEP164 onto the centrosome . This observation can be exploited experimentally:

• Molecular mechanism insights: High levels of exogenous CEP83 prevent the coordinated assembly of CEP164/DAPs onto the mother centriole, providing a tool to study assembly sequences and dependencies .

• Structure-function analysis: This dominant-negative effect is conserved for all variants that efficiently recruit to the centrosome, regardless of their capacity to interact with CEP164 or IFT20 (p.Leu87Pro, p.Pro112_Leu117del, and p.Arg511Pro) .

• Differential effects of mutations: Variants with impaired centrosomal localization (p.Gln692del, p.Glu669Aspfs*14) show reduced dominant-negative effects, helping map domains required for centrosomal targeting .

• Temporal studies: Inducible expression systems could allow temporal control of dominant-negative effects, enabling the study of CEP83 function at specific stages of the cell cycle or ciliogenesis.

• Rescue experiments: Testing whether co-expression of interaction partners at appropriate levels can overcome dominant-negative effects provides insights into stoichiometric requirements for DAP assembly.

These approaches complement loss-of-function studies by providing alternative perturbations of CEP83 function.

What experimental approach can reveal CEP83's interaction with ciliary trafficking machinery?

Research indicates CEP83 may collaborate with IFT20 in trafficking ciliary membrane proteins from the Golgi complex to the cilium . To investigate this interaction, consider:

• Co-immunoprecipitation: CEP83 forms complexes with both CEP164 and IFT20, which can be detected through co-immunoprecipitation. C-terminal CEP83 variants maintain interaction with IFT20, while N-terminal variants show decreased interaction .

• Localization studies: While CEP83 predominantly localizes to distal appendages, it has also been found at the Golgi apparatus, suggesting potential trafficking functions. Dual-color imaging with Golgi markers can reveal this population .

• Cargo tracking: Live-cell imaging with tagged ciliary membrane proteins can reveal trafficking defects in cells with CEP83 depletion or mutation.

• FRAP (Fluorescence Recovery After Photobleaching): This technique can measure the dynamics of CEP83 at both the centrosome and Golgi, providing insights into potential shuttling between these locations.

• Domain mapping: The differential effects of N-terminal versus C-terminal mutations on IFT20 interaction suggest domain-specific functions. Structure-function studies with truncation or point mutants can map interaction domains precisely .

These approaches can reveal how CEP83 contributes to the trafficking of ciliary membrane proteins, an essential process for ciliogenesis and ciliary function.

How should experiments be designed to study CEP83 in disease contexts?

When investigating CEP83's role in diseases like infantile nephronophthisis:

• Patient-derived materials: Studies using kidney biopsies from affected individuals have shown that CEP83 staining appears fainter at the centrosome and CEP164 may be absent from some centrosomes (50.1% of CEP164-positive centrosomes versus 83.6% for control) .

• Quantitative metrics: Develop quantitative readouts like the percentage of CEP164-positive centrosomes to objectively assess disease phenotypes .

• Mutation-specific effects: Different CEP83 mutations affect protein function differently. For example:

  • Deletion of single amino acids (p.Glu684del and p.Gln692del) or introduction of proline residues (p.Leu87Pro and p.Arg511Pro) affect coiled-coil domain organization

  • C-terminal variants impair interaction with CEP164, while N-terminal variants maintain this interaction

• Tissue-specific manifestations: While ciliopathies can affect multiple organs, focusing on kidney-specific effects when studying nephronophthisis ensures disease relevance .

• Developmental timing: Consider the infantile onset of nephronophthisis when designing experiments, potentially using developmental models to capture time-sensitive aspects of CEP83 function.

• Rescue experiments: Testing whether wild-type CEP83 can rescue phenotypes in patient-derived cells confirms causality and potential therapeutic approaches.

These strategies connect basic CEP83 biology to clinically relevant disease mechanisms, potentially informing therapeutic approaches for ciliopathies.

What are the most promising future directions for CEP83 antibody applications?

The study of CEP83 continues to evolve, with several promising research directions for antibody applications:

• Phospho-specific antibody development: Further development and characterization of antibodies specific to each of the four TTBK2-dependent phosphorylation sites (Ser29, Thr292, Thr527, and Ser698) would enable more precise studies of CEP83 regulation during ciliogenesis .

• Super-resolution microscopy applications: As CEP83 forms ring-shaped structures at distal appendages, super-resolution microscopy with appropriate antibodies can reveal structural details of DAP organization and remodeling during the cell cycle .

• Ciliopathy diagnostics: The association between CEP83 mutations and infantile nephronophthisis suggests potential diagnostic applications in clinical settings .

• Developmental studies: Investigating CEP83's role during embryonic development could reveal new insights into ciliopathies with developmental origins.

• Systems biology approaches: Combining CEP83 antibodies with other cilia-associated protein markers in high-content screening could identify novel regulators of ciliogenesis.