Recombinant Danio rerio Apelin receptor B (aplnrb)

What are the optimal storage conditions for maintaining aplnrb stability and activity?

For optimal stability and activity of Recombinant Danio rerio Apelin receptor B, the following storage conditions are recommended:

• Standard storage: -20°C

• Extended storage: -20°C or -80°C

• Working aliquots: 4°C for up to one week

• Avoid repeated freeze-thaw cycles as this can significantly compromise protein integrity and function

The shelf life of the protein depends on several factors including buffer composition, storage temperature, and the inherent stability of the protein itself. Generally:

• Liquid preparations: 6 months at -20°C/-80°C

• Lyophilized preparations: 12 months at -20°C/-80°C

For research requiring extended use, it is advisable to prepare small working aliquots to minimize freeze-thaw cycles and maintain protein integrity.

Which expression systems are most effective for producing functional Recombinant Danio rerio Apelin receptor B?

For transmembrane proteins like aplnrb, mammalian or insect cell expression systems often provide better functionality due to proper membrane insertion and post-translational modifications, which are crucial for maintaining native receptor conformation and ligand binding properties.

What purification strategies are recommended for obtaining high-purity aplnrb preparations?

The purification of Recombinant Danio rerio Apelin receptor B typically leverages the N-terminal 10xHis tag through the following optimized protocol:

• Solubilization: Use appropriate detergents (e.g., DDM, LMNG) to extract the receptor from membranes while maintaining native conformation

• IMAC Purification: Utilize Ni-NTA affinity chromatography with imidazole gradient elution

• Size Exclusion Chromatography: Remove aggregates and further purify monomeric receptor

• Detergent Exchange: If required for downstream applications, replace harsh solubilization detergents with milder ones

Critical Parameters to Monitor:

• Detergent concentration: Too low fails to solubilize; too high may denature

• Imidazole concentrations: Optimize to minimize non-specific binding while maximizing yield

• Buffer pH: Typically maintain pH 7.4-8.0 to preserve receptor structure

• Addition of stabilizing agents: Cholesterol hemisuccinate or specific lipids may enhance stability

For functional studies, verification of proper folding through ligand binding assays is strongly recommended post-purification.

What are the major signaling pathways associated with aplnrb in zebrafish?

Apelin receptor B in zebrafish, similar to its mammalian counterpart, couples to inhibitory G proteins (Gi/o) that inhibit adenylate cyclase activity . The signaling cascade involves several pathways with distinct physiological outcomes:

Research indicates that aplnrb signaling plays crucial roles in:

• Vascular development, particularly in lymphatic vessel formation

• Heart morphogenesis and contractility regulation

• Neural progenitor cell behavior and development

Methodologically, these pathways can be studied using phospho-specific antibodies against downstream effectors, FRET-based biosensors for real-time signaling analysis, and pharmacological inhibitors to dissect pathway components.

What phenotypes are observed in zebrafish aplnrb knockdown or knockout models?

Morpholino-mediated knockdown and genetic knockout of aplnrb in zebrafish reveal several distinct developmental phenotypes:

The dramatic lymphatic phenotypes observed in apelin signaling morpholino zebrafish raise interesting questions about the possible functions of apelin-aplnrb signaling in lymphatic vessel development and maintenance . These models provide valuable tools for studying the receptor's role in various developmental contexts.

How does neural progenitor-derived apelin influence vascular development through aplnrb?

Recent research has revealed a fascinating crosstalk between neural progenitors and vascular development mediated by apelin-aplnrb signaling:

• Expression Pattern: Using the [TgBAC(gfap:GAL4FF); Tg(UAS-E1B:NTR-mCherry)] reporter line, studies have demonstrated coexpression of apln:Venus-PEST with gfap:GAL4FF; UAS-E1B:NTR-mCherry at 26 hpf and 56 hpf in the neural tube .

• Cellular Source: Neural progenitor cells, specifically radial glia cells, express apelin (the ligand for aplnrb) during critical periods of development .

• Functional Consequence: Apelin secreted by neural progenitors acts on aplnrb-expressing vascular tip cells to regulate their behavior during angiogenesis .

• Methodological Approach: This interaction can be studied using:

  • Tissue-specific genetic ablation of apelin

  • Cell-type specific reporter lines

  • Confocal microscopy with optical transverse sections

  • Quantitative analysis of tip cell filopodia formation and migration

This neural-vascular crosstalk represents an important mechanism by which developing tissues coordinate vascularization with tissue growth and differentiation.

What in vitro assays are most informative for studying aplnrb function?

Researchers investigating aplnrb function can employ several in vitro assays to evaluate different aspects of receptor biology:

For optimal results, the recombinant aplnrb should be expressed in mammalian cells that provide appropriate membrane composition and signaling machinery. HEK293 or CHO cells are commonly used for these applications due to their transfection efficiency and low endogenous expression of related receptors.

How can researchers effectively utilize Recombinant Danio rerio Apelin receptor B in drug discovery efforts?

Recombinant Danio rerio Apelin receptor B can serve as a valuable tool in drug discovery campaigns, particularly when exploring evolutionary conservation of binding sites or developing compounds for zebrafish-based in vivo models:

• High-Throughput Screening:

  • Implement GPCR-specific screening platforms (e.g., FLIPR-based assays)

  • Utilize biosensor technologies for real-time monitoring

  • Consider biased signaling screens to identify pathway-selective compounds

• Structure-Activity Relationship Studies:

  • Compare binding profiles between zebrafish aplnrb and human APLNR

  • Identify conserved binding pockets through computational modeling

  • Develop species-selective compounds for proof-of-concept studies

• Probe Development:

  • Utilize functional agonists of apelin receptors as starting points

  • Develop fluorescent or radiolabeled ligands for binding studies

  • Create photoaffinity probes for binding site identification

• Target Validation:

  • Establish correlation between in vitro activity and in vivo phenotypic rescue

  • Use CRISPR-Cas9 knock-in models with modified aplnrb binding sites

  • Develop zebrafish-specific positive control compounds

The development of aplnrb-targeting compounds becomes particularly relevant given the receptor's roles in cardiovascular function, fluid homeostasis, and adipocyte endocrine secretion , making it a potential therapeutic target for related disorders.

How does zebrafish aplnrb function compare to human APLNR?

Understanding the similarities and differences between zebrafish aplnrb and human APLNR is critical for translational research:

This comparative analysis reveals that while core signaling mechanisms are conserved, there are important species-specific differences in expression patterns and physiological roles. These differences should be considered when using zebrafish as a model for human APLNR-related pathologies.

What evolutionary insights can be gained from studying aplnrb across species?

Evolutionary analysis of the apelin receptor system reveals important insights about conserved functions and adaptation:

• Receptor Duplication: Zebrafish possess two apelin receptors (aplnra and aplnrb) due to genome duplication, while mammals have a single receptor (APLNR) , allowing for subfunctionalization in fish.

• Ligand Evolution: The apelin signaling system has expanded to include multiple ligands including apelin and APELA (Elabela/Toddler), with distinct developmental roles that have been conserved across vertebrates.

• Methodological Approach to Evolutionary Studies:

  • Sequence alignment and phylogenetic analysis

  • Synteny mapping to identify orthologous relationships

  • Functional complementation studies across species

  • Domain swapping to identify functionally conserved regions

• Developmental Context: The role of aplnrb in zebrafish vascular and cardiac development represents an ancient function of this signaling pathway that predates the evolutionary divergence of teleosts and mammals.

Understanding these evolutionary relationships helps researchers determine which aspects of aplnrb function in zebrafish are likely to translate to human APLNR function, guiding translational research efforts.

What are the challenges in studying membrane protein-protein interactions involving aplnrb?

Investigating how aplnrb interacts with other proteins presents several methodological challenges:

Recommended workflow for aplnrb interactome analysis:

• Generate stable cell lines or zebrafish models with tagged endogenous aplnrb

• Use BioID or APEX2 proximity labeling in physiologically relevant contexts

• Confirm key interactions through reciprocal co-immunoprecipitation

• Validate functional significance through mutational analysis and phenotypic rescue

These approaches can reveal important insights into how aplnrb forms signaling complexes and interacts with downstream effectors in different cellular contexts.

How can researchers effectively design experiments to study aplnrb's role in specific developmental processes?

To effectively study aplnrb's role in development, researchers should consider these experimental design principles:

• Temporal Control:

  • Heat-shock inducible transgenes for stage-specific manipulation

  • Photoactivatable morpholinos for spatiotemporal precision

  • Drug-inducible Cre-lox systems for conditional knockout

• Spatial Resolution:

  • Tissue-specific promoters for targeted expression/knockout

  • Mosaic analysis through cell transplantation

  • Localized injection of morpholinos or mRNA

• Functional Readouts:

  • High-resolution in vivo imaging with tissue-specific reporters

  • Quantitative phenotypic analysis (e.g., vessel branching, heart function)

  • Single-cell transcriptomics to assess cell-type specific responses

• Experimental Design Example: Investigating aplnrb's role in lymphatic development

  • Generation of lymphatic-specific aplnrb knockout using Tg(lyve1:Cre)

  • Time-lapse imaging using Tg(fli1:EGFP) to visualize vessel formation

  • Quantification of lymphatic sprouting, branching and migration

  • Transcriptomic analysis of isolated lymphatic endothelial cells

  • Rescue experiments with wild-type or mutant aplnrb constructs

These approaches enable researchers to dissect the specific contributions of aplnrb signaling to various developmental processes with high precision and physiological relevance.

What emerging technologies offer new opportunities for studying aplnrb function?

Several cutting-edge technologies are opening new avenues for aplnrb research:

The application of these technologies to aplnrb research promises to advance our understanding of this receptor's complex roles in development and physiology, potentially leading to novel therapeutic strategies targeting this signaling pathway.

What are the most promising translational applications of aplnrb research?

Research on aplnrb in zebrafish has several promising translational implications:

• Cardiovascular Therapeutics: Understanding aplnrb's role in cardiac development and function could inform new treatments for heart failure, as the apelin-APJ system is known to have positive inotropic effects .

• Lymphatic Disorders: The dramatic effects of aplnrb signaling on lymphatic development suggest potential therapeutic applications for lymphedema and other lymphatic vascular disorders.

• Angiogenesis Modulation: Insights into how aplnrb regulates tip cell behavior could lead to novel approaches for controlling pathological angiogenesis in cancer or promoting therapeutic angiogenesis in ischemic diseases.

• Metabolic Disease: Given the role of apelin signaling in adipose tissue function and glucose metabolism , aplnrb research could inform treatments for obesity and diabetes.

• Neurodevelopmental Applications: The emerging understanding of neural-vascular crosstalk mediated by apelin-aplnrb could provide insights into neurodevelopmental disorders and brain vascularization.