WDR26 Antibody

What is WDR26 and what structural features characterize this protein?

WDR26 (WD repeat domain 26) is a member of the WD repeat protein family that functions as a scaffolding protein in various cellular processes. Structurally, WDR26 is a 72.1 kilodalton protein containing multiple functional domains . Its C-terminus is predicted to contain seven WD40 repeats, while its N-terminus features Lis homology (LisH) and C-terminal to LisH (CTLH) domains . These domains are critical for protein-protein interactions and protein dimerization.

WDR26 is also known by several alternative names including MIP2, CDW2, GID7, SKDEAS, WD repeat-containing protein 26, and CUL4- and DDB1-associated WDR protein 2 . The protein is primarily localized in the cytoplasm where it mediates its scaffolding functions . The human WDR26 gene (Gene ID: 80232, Swiss Prot: Q9H7D7) encodes this protein, and two transcript variants encoding different isoforms have been identified . Recent structural studies have demonstrated that WDR26 can form homodimers that bridge two core-CTLH E3 complexes, generating giant, hollow oval-shaped supramolecular assemblies .

What types of WDR26 antibodies are available for research applications?

Researchers have access to multiple types of WDR26 antibodies that vary in their host species, clonality, and applications. Polyclonal antibodies raised in rabbits are common, such as those generated using KLH-conjugated synthetic peptides derived from human WDR26 . These antibodies typically target epitopes within specific regions of the protein, such as amino acids 101-200 of the 514-amino acid sequence .

Several suppliers offer WDR26 antibodies with different specifications. For instance, polyclonal antibodies from Bioss are unconjugated IgG antibodies that can be used across multiple applications . Affinity-purified antibodies are also available, such as those from Bethyl Laboratories that specifically target human WDR26 . Additionally, region-specific antibodies that target particular domains of WDR26, like the C-terminal region, are available from providers such as Aviva Systems Biology . These various antibody options allow researchers to select the most appropriate reagent based on their specific experimental requirements and target species.

What are the validated applications for WDR26 antibodies in research?

WDR26 antibodies have been validated for numerous research applications across diverse experimental techniques. Western blotting (WB) is the most commonly validated application, with most antibodies showing strong reactivity in this format . This technique allows researchers to detect WDR26 in cell or tissue lysates following protein separation by SDS-PAGE.

Immunoprecipitation (IP) is another critical application, particularly for studying protein-protein interactions involving WDR26. Researchers have successfully used anti-FLAG antibodies to immunoprecipitate FLAG-tagged WDR26 from both cell lysates and purified protein preparations to study its interactions with binding partners such as Gβγ and PLCβ2 .

Immunohistochemistry applications include both paraffin-embedded (IHC-P) and frozen (IHC-F) tissue sections . Immunofluorescence techniques are validated for both tissue sections and cultured cells (IF/ICC), enabling researchers to visualize the subcellular localization of WDR26 . Additional validated applications include enzyme-linked immunosorbent assay (ELISA) and flow cytometry (FCM), broadening the experimental toolkit available to WDR26 researchers .

What species reactivity do WDR26 antibodies exhibit and how can cross-reactivity be verified?

WDR26 antibodies demonstrate reactivity across multiple species, with most commercial antibodies validated for human, mouse, and rat samples . This multi-species reactivity reflects the evolutionary conservation of WDR26 across mammalian species. Some antibodies also have predicted reactivity to WDR26 from other species such as dog, cow, horse, and chicken, though these applications typically require additional validation by researchers .

To verify cross-reactivity, researchers should conduct preliminary experiments using positive control samples from the target species. Western blotting is particularly useful for this purpose, as it allows visualization of the molecular weight of the detected protein, which should match the expected size of WDR26 (approximately 72.1 kDa) . It's also advisable to include negative controls lacking WDR26 expression, such as knockout cell lines or tissues where available, or samples where WDR26 has been knocked down using siRNA approaches as demonstrated in previous studies .

Verification of antibody specificity across species is crucial before proceeding with more complex experiments, particularly when using the antibody in novel contexts or with species outside the manufacturer's validated list.

What are the optimal protocols for immunoprecipitating WDR26 and its interacting partners?

Successful immunoprecipitation of WDR26 and its binding partners requires careful optimization of experimental conditions. For co-immunoprecipitation of FLAG-tagged WDR26 with endogenous Gβγ and PLCβ2, researchers have developed effective protocols in cellular systems. In Jurkat T cells, cells should first be serum-starved for 4-6 hours before stimulation with appropriate ligands such as SDF1α (50 nM) . To stabilize protein complexes prior to lysis, researchers can use cross-linking reagents such as dithiobis(succinimidyl propionate) (1 mM) for approximately 40 minutes at room temperature, followed by quenching with 50 mM Tris-HCl (pH 7.4) .

Cell lysis should be performed using radioimmune precipitation assay (RIPA) buffer containing appropriate protease inhibitors. For capturing FLAG-tagged WDR26, anti-FLAG M2 antibody conjugated to Dynabeads protein G has proven effective . When working with stable protein complexes that don't require cross-linking, a modified RIPA buffer (50 mM Tris-HCl, pH 7.4, 150 mM NaCl, 1% Nonidet P-40, 1 mM EDTA) can be used .

For in vitro binding assays with purified proteins, FLAG-WDR26 can be immunoprecipitated from Sf9 cell lysates and then incubated with purified binding partners such as PLCβ2 in an appropriate buffer (50 mM Tris-HCl, pH 8.0, 150 mM NaCl, 1 mM EDTA, 0.2% Nonidet P-40) . Extensive washing (five or more times) is critical to remove lipids and non-specifically bound proteins.

How can WDR26 antibodies be used to investigate protein-protein interactions in cell signaling complexes?

WDR26 antibodies are powerful tools for investigating the formation and dynamics of signaling complexes. Co-immunoprecipitation experiments using WDR26 antibodies can reveal both constitutive and stimulus-induced protein interactions. For example, immunoprecipitation analyses of FLAG-WDR26 from Jurkat T cells have demonstrated that WDR26 associates with endogenous PLCβ2 in both unstimulated and stimulated conditions, while its interaction with Gβγ is enhanced following SDF1α stimulation .

For studying direct protein-protein interactions, in vitro binding assays with purified components can be performed. WDR26 antibodies can be used to immunoprecipitate purified WDR26 protein, followed by incubation with potential binding partners at varying concentrations to determine binding affinity and specificity . This approach has been used to demonstrate that WDR26 directly binds both Gβγ and PLCβ2, with binding sites on Gβγ that are overlapping but not identical .

To investigate the effects of small molecule inhibitors on protein-protein interactions, researchers can pre-incubate potential binding partners with inhibitors before performing co-immunoprecipitation experiments. For instance, compounds like M119, gallein, and M119B have been used to study their effects on Gβγ binding to FLAG-WDR26 . Combined with structural information about WDR26, these approaches can provide detailed insights into the molecular mechanisms governing signaling complex assembly.

What are the optimal dilutions and conditions for using WDR26 antibodies in different experimental applications?

Optimal antibody dilutions vary significantly across different experimental applications. For WDR26 antibodies, the following dilution ranges have been validated:

These ranges provide starting points, but researchers should optimize dilutions for their specific experimental systems . For Western blotting, the appropriate dilution will depend on the expression level of WDR26 in the sample and the sensitivity of the detection system. For immunostaining applications, the fixation method, antigen retrieval procedure, and detection system will all influence the optimal antibody concentration.

Storage conditions are also critical for maintaining antibody performance. Most WDR26 antibodies are stable when stored at -20°C for up to one year, preferably in a storage buffer containing glycerol to prevent freeze-thaw damage . Repeated freeze-thaw cycles should be avoided as they can degrade antibody quality and reduce binding efficiency.

How can researchers validate the specificity and sensitivity of WDR26 antibodies?

Validating antibody specificity is essential for generating reliable research data. For WDR26 antibodies, several complementary approaches should be employed. First, researchers should verify that the antibody detects a protein of the expected molecular weight (approximately 72.1 kDa) in Western blotting applications . Additionally, the signal should be stronger in tissues or cells known to express WDR26 at high levels.

RNA interference provides another powerful validation method. If the antibody is specific for WDR26, the signal should be reduced in samples where WDR26 has been knocked down using siRNAs or shRNAs. This approach has been successfully employed in previous studies of WDR26 function .

For immunofluorescence applications, researchers should confirm that the subcellular localization pattern detected by the antibody matches the expected cytoplasmic distribution of WDR26 . Comparison of staining patterns across multiple antibodies targeting different epitopes of WDR26 can provide additional validation.

Overexpression experiments using tagged versions of WDR26 can also help validate antibody specificity. The antibody should detect both endogenous and overexpressed WDR26, and the signal from the overexpressed protein should correlate with expression levels determined by an antibody against the tag.

How does WDR26 function as a scaffolding protein in G-protein-mediated signaling pathways?

WDR26 serves as a critical scaffolding protein that enhances the efficacy of Gβγ-mediated signaling in leukocytes. Research has demonstrated that WDR26 directly binds to both Gβγ subunits and downstream effectors like PLCβ2, facilitating the formation of signaling complexes . This scaffolding function is essential for efficient signal transduction in response to chemokine stimulation.

In Jurkat T cells stimulated with the chemokine SDF1α, WDR26 forms a complex with endogenous Gβγ, as demonstrated by co-immunoprecipitation experiments . This interaction is dependent on chemokine receptor activation, as it can be blocked by pertussis toxin, which inhibits Gαi signaling . The binding of WDR26 to Gβγ appears to be direct, as demonstrated by in vitro binding assays with purified proteins .

Beyond its role in complex formation, WDR26 modulates the interaction of Gβγ with both positive and negative regulators. For instance, WDR26 has been shown to control RACK1, a negative regulator, in binding Gβγ and inhibiting leukocyte migration . This regulatory function positions WDR26 as a central coordinator of Gβγ-dependent signaling networks, influencing both the strength and specificity of downstream signaling events.

What is the mechanism by which WDR26 promotes PLCβ2 activation in leukocytes?

WDR26 enhances PLCβ2 activation through multiple mechanisms. First, WDR26 directly binds to both Gβγ and PLCβ2, forming a trimeric signaling complex . Although the binding sites of WDR26 and PLCβ2 on Gβ1γ2 are overlapping but not identical, WDR26 still successfully promotes complex formation . This is possible because WDR26 forms higher-order oligomers through its LisH-CTLH and WD40 domains, which appears to be required for promoting PLCβ2 interaction with and activation by Gβγ .

Second, WDR26 facilitates the translocation of PLCβ2 from the cytosol to the plasma membrane in polarized leukocytes . This translocation is a critical step in PLCβ2 activation, as it brings the enzyme into proximity with its substrate phosphatidylinositol 4,5-bisphosphate (PIP2) and its activator Gβγ. Interestingly, studies have shown that the membrane translocation of PLCβ2 mediated by WDR26 is sufficient to cause partial activation of the enzyme, even in the absence of other stimuli .

Together, these mechanisms—complex formation, oligomerization, and membrane translocation—establish WDR26 as a master regulator of PLCβ2 signaling in leukocytes. By coordinating the assembly and localization of signaling components, WDR26 ensures efficient and specific signal transduction in response to chemokine stimulation.

How do structural features of WDR26 contribute to its function in signaling complexes?

The structural features of WDR26 are intimately linked to its function in signaling complexes. WDR26 contains several distinct domains, including seven WD40 repeats in its C-terminus and LisH and CTLH domains in its N-terminus . These domains serve different but complementary functions in mediating protein-protein interactions and oligomerization.

The WD40 repeats typically fold into a β-propeller structure that provides a stable platform for protein interactions. In WDR26, these repeats are involved in binding to both Gβγ and PLCβ2 . The LisH and CTLH domains, on the other hand, are primarily involved in protein dimerization and higher-order oligomerization . Studies have shown that WDR26 forms higher-order oligomers through these domains, and this oligomerization is required for its ability to promote PLCβ2 interaction with Gβγ .

Recent structural studies have further revealed that WDR26 homodimers serve as bridges between two core-CTLH E3 complexes, generating giant, hollow oval-shaped supramolecular CTLH E3 assemblies . This suggests that WDR26 may have broader roles in organizing macromolecular complexes beyond its known function in G-protein signaling.

The multidomain architecture of WDR26 thus enables it to simultaneously bind multiple proteins and form higher-order structures, positioning it as a versatile scaffolding protein in diverse cellular contexts.

What experimental approaches can detect WDR26-dependent changes in downstream signaling pathways?

Researchers can employ multiple experimental approaches to investigate WDR26-dependent signaling changes. RNA interference (siRNA or shRNA) targeting WDR26 has been successfully used to suppress its expression in leukocytes, revealing its role in Gβγ-mediated PI3K and PLCβ activation . Following WDR26 knockdown, researchers observed attenuated chemotaxis in Jurkat T cells and differentiated HL60 cells in vitro, as well as impaired Jurkat T cell homing to lymphoid tissues in scid mice .

Another powerful approach involves expressing WDR26 deletion mutants that can disrupt the WDR26/Gβγ interaction. This strategy has demonstrated that the function of WDR26 depends on its binding to Gβγ, as expression of these mutants impaired Gβγ signaling and Jurkat T cell migration . By combining these genetic manipulation approaches with biochemical assays of downstream signaling events, researchers can dissect the specific contributions of WDR26 to various signaling pathways.

For studying PLCβ2 activation specifically, researchers can monitor calcium mobilization using fluorescent calcium indicators or measure the production of inositol phosphates following stimulation with chemokines like SDF1α . Phosphorylation of downstream targets can be assessed by Western blotting with phospho-specific antibodies, while membrane translocation of signaling components can be visualized using immunofluorescence or live cell imaging techniques .

What is known about WDR26's role in leukocyte migration and inflammatory responses?

WDR26 plays a central role in regulating leukocyte migration through its effects on Gβγ-mediated signaling pathways. Studies have demonstrated that WDR26 is required for efficient chemotaxis in multiple leukocyte types, including Jurkat T cells and differentiated HL60 cells . Suppression of WDR26 expression using siRNAs significantly attenuated chemotaxis in these cells, highlighting its importance in cell motility .

Beyond in vitro migration, WDR26 also regulates leukocyte trafficking in vivo. Experiments in scid mice have shown that normal WDR26 function is required for proper Jurkat T cell homing to lymphoid tissues . This finding suggests that WDR26 may be important for immune cell recruitment during inflammatory responses and immune surveillance.

The mechanism by which WDR26 promotes leukocyte migration involves its enhancement of Gβγ-dependent signaling pathways, particularly those involving phospholipase Cβ (PLCβ) and phosphoinositide 3-kinase (PI3K) . Both of these signaling modules are critical for sensing chemokine gradients and translating them into directional migration. By scaffolding the interaction between Gβγ and these effectors, WDR26 ensures efficient signal transduction and precise cell movement in response to chemotactic stimuli.

How does WDR26 relate to the CTLH E3 ubiquitin ligase complex and protein degradation pathways?

Recent structural studies have revealed an important role for WDR26 in organizing the CTLH E3 ubiquitin ligase complex. WDR26 forms homodimers that bridge two core-CTLH E3 complexes, generating giant, hollow oval-shaped supramolecular assemblies . This structural arrangement suggests that WDR26 may regulate the activity or substrate specificity of the CTLH E3 ligase complex.

The CTLH E3 ligase complex is involved in protein ubiquitination, which marks proteins for degradation by the proteasome. Given WDR26's role in this complex, it likely contributes to protein quality control and the regulated degradation of specific substrates. This function positions WDR26 at the intersection of signal transduction and protein homeostasis.

Additional evidence for WDR26's role in protein degradation comes from its association with GID7, which is another of its alternative names . The GID (glucose-induced degradation) complex is involved in the ubiquitination and degradation of gluconeogenic enzymes following a shift from gluconeogenic to glycolytic conditions. WDR26's incorporation into this complex suggests it may regulate metabolic adaptation through protein degradation.

What is the relationship between WDR26 mutations and Skraban-Deardorff intellectual disability syndrome?

Skraban-Deardorff intellectual disability syndrome has been associated with mutations in the WDR26 gene . This rare neurodevelopmental disorder is characterized by intellectual disability, distinctive facial features, and various developmental abnormalities. The connection between WDR26 and this syndrome highlights the importance of WDR26 in normal brain development and function.

The association of WDR26 with this syndrome has prompted increased interest in understanding how alterations in WDR26 structure and function might contribute to neurodevelopmental abnormalities. Recent structural studies revealing WDR26's role in forming supramolecular CTLH E3 assemblies provide a potential mechanistic link . Disruption of these assemblies due to mutations could alter protein degradation pathways critical for neuronal development and function.

How can researchers use WDR26 antibodies to investigate neurodevelopmental disorders?

WDR26 antibodies offer valuable tools for investigating the role of this protein in neurodevelopmental disorders such as Skraban-Deardorff intellectual disability syndrome. Immunohistochemistry using WDR26 antibodies can reveal the expression pattern of WDR26 in normal and pathological brain tissues, providing insights into regional differences that might correlate with disease manifestations . Both paraffin-embedded and frozen tissue sections can be used for these analyses, with appropriate optimization of antibody dilutions (1:200-400 for IHC-P and 1:100-500 for IHC-F) .

For investigating cellular mechanisms, immunofluorescence microscopy using WDR26 antibodies enables researchers to visualize the subcellular localization of WDR26 in neuronal cultures or brain slices . This approach can reveal whether disease-associated mutations alter the localization or expression level of WDR26 in relevant cell types.

Western blotting applications using WDR26 antibodies allow quantitative assessment of WDR26 protein levels in brain samples from patients or animal models . This technique can determine whether specific mutations affect protein stability or expression. Co-immunoprecipitation experiments can further reveal whether disease-associated mutations disrupt WDR26's interaction with binding partners critical for neuronal function, such as components of the CTLH E3 ligase complex or signaling molecules involved in neuronal development .

What are promising research directions for understanding WDR26's broader cellular functions?

Future research on WDR26 should explore its emerging roles beyond Gβγ signaling and leukocyte migration. The discovery that WDR26 forms homodimers that bridge CTLH E3 complexes into supramolecular assemblies opens new avenues for investigating its role in protein degradation pathways . Studies examining how WDR26 contributes to substrate recognition and ubiquitination by these complexes could reveal important mechanisms of cellular protein homeostasis.

Additionally, the association of WDR26 with Skraban-Deardorff intellectual disability syndrome highlights the need for deeper investigation of its functions in neuronal development and signaling . Studies using neuronal cell cultures, brain organoids, or animal models carrying WDR26 mutations could provide valuable insights into how this protein contributes to normal brain development and function.

WDR26 has also been implicated in the regulation of MAPK signaling pathways and in neuronal and cardiomyoblast cell proliferation and apoptosis . These findings suggest broader roles in cellular growth, differentiation, and survival that warrant further exploration. Systematic interactome studies using proteomics approaches could identify additional binding partners and cellular pathways regulated by WDR26, expanding our understanding of its multifaceted functions.

How might technological advances improve WDR26 antibody development and applications?

Emerging technologies promise to enhance both the development and application of WDR26 antibodies. Single B cell cloning techniques enable the generation of monoclonal antibodies with exquisite specificity for particular epitopes of WDR26. These highly specific antibodies could differentiate between closely related WD40 repeat proteins or even distinguish between different conformational states of WDR26.

Advances in antibody engineering, such as the development of nanobodies (single-domain antibodies derived from camelids) or synthetic antibody mimetics, offer new possibilities for creating tools that can access epitopes that conventional antibodies cannot reach. These smaller binding molecules might be particularly useful for probing the function of WDR26 within densely packed protein complexes like the supramolecular CTLH E3 assemblies .

Super-resolution microscopy techniques combined with appropriately labeled WDR26 antibodies will enable researchers to visualize WDR26-containing complexes with unprecedented spatial resolution. This could provide new insights into the dynamics of complex assembly and disassembly in living cells.

CRISPR-Cas9 gene editing technologies facilitate the generation of endogenously tagged WDR26, allowing researchers to study the protein under physiological expression conditions. When combined with specific antibodies against these tags, this approach offers advantages over conventional overexpression systems for studying WDR26 function.

What challenges remain in the field of WDR26 research and antibody development?

Despite significant progress, several challenges persist in WDR26 research. The structural complexity of WDR26-containing complexes, particularly the supramolecular CTLH E3 assemblies, presents technical difficulties for detailed structural characterization . Cryo-electron microscopy and other advanced structural biology techniques will be essential for resolving these structures at atomic resolution.

Another challenge lies in understanding the tissue-specific and context-dependent functions of WDR26. While its role in leukocyte migration is well-established , its functions in other cell types, particularly neurons, remain less clear. Developing tissue-specific knockout or knockin models will be crucial for dissecting these functions without confounding systemic effects.

For antibody development specifically, generating reagents that can distinguish between different conformational states or post-translationally modified forms of WDR26 remains challenging. Such antibodies would be valuable for investigating how WDR26's function is regulated in different cellular contexts. Additionally, developing antibodies that can specifically disrupt particular protein-protein interactions involving WDR26 could provide powerful tools for dissecting its various functions.

Finally, translating basic research findings on WDR26 into clinical applications, particularly for conditions like Skraban-Deardorff intellectual disability syndrome, presents significant challenges that will require collaborative efforts across basic science, translational research, and clinical medicine.