Recombinant Danio rerio Blood vessel epicardial substance (bves)

What is the expression pattern of bves during zebrafish development?

Bves shows dynamic expression patterns during zebrafish development:

The protein is prominently expressed in developing cardiac tissues, particularly in the epicardium. It is also found in blood vessel junctions and various epithelial tissues. Expression analysis using transgenic zebrafish lines like TgBAC(bves:EGFP) reveals that bves is expressed in meningeal fibroblast-like cells and tight junctions between endothelial cells, suggesting its importance in maintaining vascular integrity .

How does bves function differ between zebrafish and mammalian models?

While the fundamental functions of bves are conserved between zebrafish and mammals, several important differences exist:

Zebrafish bves appears particularly important in regenerative contexts, consistent with the zebrafish's remarkable ability to regenerate cardiac tissue. In contrast, mammalian BVES functions more prominently in maintaining epithelial integrity and preventing epithelial-to-mesenchymal transition in adult tissues .

How does bves contribute to blood vessel formation and maintenance in zebrafish?

Bves plays a multifaceted role in zebrafish vascular biology through several mechanisms:

• Junctional integrity maintenance: As a tight junction protein, bves helps establish and maintain endothelial cell-cell contacts crucial for vessel formation. Loss of bves function results in compromised junctional integrity, leading to leaky vessels.

• Vascular patterning regulation: Research indicates that bves interacts with the Vegf signaling pathway, which is essential for proper vessel patterning. In particular, bves appears to modulate the response of endothelial cells to Vegf gradients, affecting vessel branching and migration patterns.

• Vessel stabilization: During vessel maturation, bves contributes to vessel stabilization by mediating interactions between endothelial cells and mural cells (pericytes and smooth muscle cells).

• Endothelial cell polarity: Bves regulates endothelial cell polarity, which is crucial for lumen formation and directional angiogenic sprouting.

Recent experiments using bves mutant zebrafish have demonstrated defects in the formation of specific vessels like the dorsal longitudinal vein (DLV), suggesting that bves cooperates with vascular endothelial growth factors in vessel-type specific development. The phenotypes observed in these mutants include aberrant branching patterns, reduced vessel stability, and compromised barrier function .

What are the interactions between bves and vascular endothelial growth factor (Vegf) signaling pathways?

The relationship between bves and Vegf signaling represents a critical intersection in vascular development:

Research in zebrafish has revealed that bves functions in parallel with specific Vegf ligands (Vegfab, Vegfc, and Vegfd) in driving the formation of fenestrated vessels in the zebrafish brain. Experimental evidence suggests that bves may be particularly important for the development of specialized vascular beds with unique permeability properties, such as those found in the choroid plexus.

For example, studies have shown that combined deficiency of bves and components of the Vegf pathway results in more severe vascular defects than individual mutations, suggesting functional redundancy or compensation. The interaction appears most significant in vessels with specialized barrier properties, indicating a potential role for bves in regulating vessel permeability in response to Vegf signaling .

What molecular mechanisms underlie bves function in epithelial and endothelial barrier formation?

Bves employs several molecular mechanisms to regulate barrier formation:

• cAMP signaling modulation: The Popeye domain of bves binds cAMP, allowing it to function as a cAMP effector protein. This binding affects junctional protein complex assembly and stability.

• WNT pathway regulation: Bves inhibits the WNT signaling pathway by sequestering β-catenin at cell junctions, preventing its nuclear translocation and subsequent transcriptional activity.

• c-Myc degradation promotion: Research has shown that bves promotes the degradation of the oncogene c-Myc, which normally drives proliferation and can disrupt barrier integrity when overexpressed.

• ZO-1 and Claudin recruitment: Bves facilitates the proper localization of ZO-1 and Claudins to tight junctions, essential components for establishing paracellular barrier properties.

• Cytoskeletal anchoring: Through interaction with cytoskeletal elements, bves helps maintain the structural scaffold necessary for stable junctions.

These mechanisms collectively contribute to bves's role in establishing and maintaining epithelial and endothelial barriers. Disruption of bves function leads to increased permeability and compromised tissue integrity, as demonstrated in both zebrafish models and mammalian systems .

How does bves contribute to cardiac development and regeneration in zebrafish?

Bves plays multifaceted roles in zebrafish cardiac biology:

During cardiac regeneration, bves expression is dynamically regulated, with upregulation observed in the injury border zone. This pattern suggests its involvement in the regenerative process, potentially through regulating epicardial activation, cardiomyocyte dedifferentiation, and proliferation, and neovascularization.

Experimental evidence indicates that bves works in concert with macrophages during the regenerative process. When macrophages are depleted using clodronate liposomes, both revascularization and cardiomyocyte proliferation are impaired, suggesting a potential interaction between immune-mediated processes and bves function in cardiac repair .

What are the optimal conditions for expression and purification of recombinant Danio rerio bves protein?

Optimal expression and purification of recombinant Danio rerio bves requires careful consideration of multiple factors:

Expression System Recommendations:

Purification Protocol:

• Lysis buffer composition: 50 mM Tris-HCl pH 8.0, 300 mM NaCl, 10% glycerol, 1% Triton X-100, protease inhibitor cocktail

• Affinity chromatography: For His-tagged bves, use Ni-NTA resin with step gradient elution (50, 100, 250, 500 mM imidazole)

• Secondary purification: Size exclusion chromatography using Superdex 200 in buffer containing 20 mM Tris-HCl pH 7.5, 150 mM NaCl, 5% glycerol

• Quality control: SDS-PAGE with Western blot confirmation; dynamic light scattering for aggregation assessment

• Storage: Aliquot in Tris/PBS-based buffer with 6% trehalose, pH 8.0; flash freeze and store at -80°C

This methodology consistently yields >90% pure protein as determined by SDS-PAGE. For functional studies, reconstitute the lyophilized protein in deionized sterile water to a concentration of 0.1-1.0 mg/mL with 5-50% glycerol for long-term storage at -20°C/-80°C .

What genetic tools and techniques are most effective for studying bves function in zebrafish?

Several genetic approaches have proven effective for investigating bves function in zebrafish:

Knockout/Knockdown Technologies:

Reporter Systems:

• Transgenic reporter lines: Develop Tg(bves:EGFP) for expression pattern analysis

• Bicistronic constructs: bves-2A-fluorescent protein for simultaneous expression and visualization

• Protein fusion tags: C-terminal tags preferable to minimize functional disruption

Conditional Systems:

• Heat-shock inducible promoters: For temporal control of bves expression

• Tissue-specific drivers: Using endothelial (kdrl) or epicardial (tcf21) promoters

• Cre/lox recombination systems: For lineage tracing of bves-expressing cells

Research has successfully used these approaches to study bves function in various contexts. For instance, CRISPR/Cas9-generated bves mutants have revealed its role in vessel formation, while transgenic lines expressing fluorescently tagged bves have enabled live imaging of protein localization during development and regeneration .

What advanced imaging techniques are most informative for visualizing bves localization and function in zebrafish vascular development?

Advanced imaging approaches provide crucial insights into bves dynamics:

Recommended Imaging Techniques:

Optimized Protocols:

• For developmental studies: Utilize Tg(kdrl:EGFP; bves:mCherry) double transgenic lines with light sheet microscopy for long-term (12-48 hours) imaging of bves in developing vasculature. Image acquisition every 5-15 minutes minimizes phototoxicity while capturing dynamic processes.

• For junctional analysis: Implement airyscan or STED microscopy of fixed samples using immunolabeling for bves and other junction proteins (ZO-1, VE-cadherin). This approach reveals nanoscale organization of junctional complexes.

• For functional studies: Combine microangiography using fluorescent quantum dots with bves visualization to correlate protein distribution with vessel functionality and permeability.

Recent studies have demonstrated that live confocal imaging of zebrafish embryos expressing Tg(kdrl:EGFP) to mark endothelial cells, combined with bves antibody staining, provides valuable insights into how bves influences vessel formation. These approaches have revealed that bves is enriched at endothelial cell junctions during critical periods of vessel stabilization and maturation .

What experimental approaches best reveal the molecular interactions of bves with other proteins in zebrafish?

Multiple complementary approaches effectively reveal bves protein interactions:

In Vivo Interaction Approaches:

Biochemical Interaction Methods:

• Co-immunoprecipitation: Using anti-bves antibodies or epitope tags to pull down protein complexes from zebrafish tissue lysates

• GST pull-down assays: With recombinant GST-bves domains to identify direct binding partners

• Yeast two-hybrid screens: Using the cytoplasmic domain of bves as bait against zebrafish cDNA libraries

• Mass spectrometry-based interactomics: Label-free quantitative proteomics comparing bves-associated proteins between wild-type and bves-mutant samples

Data Integration:

Combining multiple approaches strengthens confidence in identified interactions. For example, potential interactions identified by mass spectrometry can be validated by co-immunoprecipitation and subsequently visualized in vivo using PLA or FRET.

Research using these methodologies has revealed that bves interacts with tight junction proteins (claudins, ZO-1), components of the WNT signaling pathway (β-catenin), and regulators of the cytoskeleton. These interactions appear to mediate bves's functions in maintaining epithelial and endothelial barriers .

How does bves function in specialized vascular beds with unique barrier properties?

Current research is uncovering distinct roles for bves in specialized vascular territories:

Research has shown that bves participates in the development of fenestrated vessels in specific regions like the choroid plexus through interactions with the Vegf signaling pathway. In zebrafish models, bves appears to work alongside Vegfab, Vegfc, and Vegfd to selectively drive fenestrated vessel formation in the brain.

Methodologically, researchers are employing sophisticated approaches including:

• Tissue-specific genetic manipulation using Gal4/UAS systems

• Barrier integrity assessment with size-selective tracers

• Transcriptomic profiling of isolated vascular beds

• Live imaging of vessel-neural tissue interface development

These studies are revealing that bves may have specialized functions in different vascular beds, potentially explaining the selective vulnerability of certain vessels to bves dysfunction .

What is the role of bves in modulating inflammatory responses in zebrafish vascular systems?

Emerging evidence suggests bves plays important roles in vascular inflammatory responses:

• Barrier maintenance during inflammation: Bves helps maintain endothelial barrier integrity during inflammatory challenges, potentially by stabilizing junctional complexes against cytokine-induced disruption.

• Leukocyte recruitment regulation: Studies suggest bves influences leukocyte-endothelial interactions during inflammatory responses, possibly by modulating adhesion molecule expression or distribution.

• Oxidative stress response: Bves appears to participate in the endothelial response to hydrogen peroxide (H₂O₂), an important inflammatory mediator and signaling molecule in zebrafish.

• Macrophage-vessel interaction: Research indicates that bves may mediate communication between macrophages and blood vessels during injury responses and tissue regeneration.

The experimental approaches revealing these functions include:

• Chemical injury models using copper sulfate or hydrogen peroxide exposure

• Heat-shock inducible inflammation models

• Clodronate liposome-mediated macrophage depletion

• Live imaging of neutrophil and macrophage recruitment in transgenic lines

For example, studies have shown that in cardiac regeneration models, bves expression is modulated in response to injury signals, and this response appears coordinated with macrophage recruitment patterns. When macrophages are depleted using clodronate liposomes, both revascularization and tissue regeneration are impaired, suggesting potential crosstalk between immune-mediated processes and bves function .

How can high-throughput approaches advance our understanding of bves in zebrafish vascular biology?

High-throughput technologies offer transformative potential for bves research:

Integrative Data Analysis Frameworks:

• Multi-omics integration: Combining transcriptomics, proteomics, and metabolomics data to build comprehensive models of bves function in vascular development

• Network analysis: Constructing protein-protein interaction and genetic networks centered on bves to identify key nodes and relationships

• Machine learning approaches: Developing predictive models of vascular development based on bves expression patterns and genetic backgrounds

Recent applications include high-content imaging platforms that can analyze hundreds of zebrafish embryos to quantify subtle vascular phenotypes in response to genetic or pharmacological manipulations of bves. These approaches are revealing previously unrecognized roles of bves in specific vascular beds and developmental timepoints .

Comparative Expression Data of bves Across Zebrafish Tissues

Expression levels: +++ (high), ++ (moderate), + (low), - (undetectable)

This comparative expression data reveals that bves shows preferential expression in tissues with specialized barrier or regenerative functions, consistent with its proposed roles in maintaining tissue integrity and participating in repair processes .

Key Research Models and Resources for Studying Zebrafish bves

These resources collectively provide the essential tools for comprehensive investigation of bves biology in zebrafish models. The continued development and sharing of these resources through repositories and collaborative networks are accelerating research in this field .