aplnrb Antibody

What is APLNR and why is it significant for antibody-based research?

APLNR (Apelin Receptor) is a member of the G protein-coupled receptor gene family. Though related to the angiotensin receptor, APLNR functions as an apelin receptor that inhibits adenylate cyclase activity and plays a counter-regulatory role against the pressure action of angiotensin II by exerting hypertensive effects .

The significance of APLNR in research stems from its diverse functions in:

• Cardiovascular and central nervous systems

• Glucose metabolism regulation

• Embryonic and tumor angiogenesis

• Acting as a human immunodeficiency virus (HIV-1) coreceptor

Recent research has demonstrated APLNR's involvement in cancer biology, particularly in nasopharyngeal carcinoma where it inhibits growth and immune escape , and in glioblastoma where it controls angiogenesis and invasion .

Interestingly, there is a notable discrepancy between the calculated and observed molecular weights of APLNR:

• Calculated molecular weight: approximately 42.7 kDa (42,660 Da)

• Observed molecular weight: approximately 111 kDa

This significant difference is likely due to post-translational modifications, particularly glycosylation, which is common for membrane receptors like APLNR. When interpreting Western blot results, researchers should anticipate bands at the higher observed molecular weight rather than the calculated weight .

How can I distinguish between phosphorylated and non-phosphorylated forms of APLNR?

For researchers specifically interested in APLNR phosphorylation states:

• Non-phospho-specific antibodies: Antibodies like the non-phospho-APLNR antibody (catalog #7TM0036N) are directed against the distal end of the carboxyl-terminal tail of human apelin receptor and detect total APLNR independent of phosphorylation status .

• Methodology for distinguishing phosphorylation states:

  • Use phosphatase treatment on duplicate samples

  • Employ paired antibodies (phospho-specific and total)

  • Use lambda phosphatase treatment to confirm phospho-specificity

  • Consider 2D gel electrophoresis to separate phosphorylated forms

When conducting studies on APLNR signaling, understanding the phosphorylation status can provide crucial insights into receptor activation and downstream signaling events .

What experimental strategies can optimize APLNR antibody specificity in cancer research?

Recent studies highlight APLNR's importance in cancer biology, requiring specialized approaches:

• For nasopharyngeal carcinoma (NPC) studies:

  • APLNR has been shown to inhibit PD-L1 expression by binding to the FERM domain of JAK1 and blocking interaction between JAK1 and IFNGR1

  • APLNR suppresses IFN-γ-mediated activation of the JAK1/STAT1 pathway

  • Consider dual staining with APLNR and PD-L1 antibodies, as they show negative correlation in NPC tissues

• For glioblastoma (GBM) research:

  • APLNR antibodies can be used to investigate the relationship between APLNR signaling and VEGF/VEGFR2 pathways

  • Co-staining with angiogenesis markers provides insights into tumor vascularization mechanisms

  • Consider examining APLNR-positive cell populations for invasion and migration properties

How do recombinant monoclonal versus polyclonal APLNR antibodies compare in research applications?

Recombinant rabbit monoclonal antibodies offer particular advantages including better specificity and sensitivity, lot-to-lot consistency, animal origin-free formulations, and broader immunoreactivity due to larger rabbit immune repertoire . For critical quantitative studies where reproducibility is essential, recombinant monoclonals may be preferred .

What validation approaches should I use to confirm APLNR antibody specificity?

A multi-faceted validation approach is recommended:

• Positive and negative controls:

  • Use APLNR-transfected cells (e.g., HEK293 cells stably expressing APLNR) versus mock-transfected cells

  • This approach has been documented for validating APLNR antibodies like 7TM0036N

• Multiple detection methods:

  • Cross-validate using different techniques (WB, IHC, IF)

  • Compare results with mRNA expression data

• Knockout/knockdown validation:

  • Use APLNR knockout or knockdown systems

  • Studies have utilized APLNR knockdown to validate antibody specificity in cancer research models

• Peptide competition assays:

  • Pre-incubate antibody with immunizing peptide

  • Observe signal reduction in pre-absorbed samples

How can APLNR antibodies be integrated into studies examining tumor immunotherapy resistance?

Recent research highlights the potential of APLNR in immunotherapy applications:

• APLNR in immune checkpoint pathways:

  • APLNR negatively regulates PD-L1 expression in nasopharyngeal carcinoma

  • This regulation occurs through inhibition of the JAK1/STAT1 pathway activation by IFN-γ

  • APLNR enhances IFN-γ secretion and CD8+ T-cell infiltration while reducing CD8+ T-cell apoptosis and dysfunction

• Experimental design recommendations:

  • Use APLNR antibodies in combination with immune checkpoint markers

  • Consider triple staining for APLNR, PD-L1, and CD8 to examine spatial relationships

  • Incorporate APLNR expression analysis in studies of immunotherapy resistance

• Therapeutic potential:

  • Combining APLNR targeting with PD-L1 antibody treatment showed enhanced efficacy in inhibiting NPC growth in mouse models

  • This suggests APLNR may be a potential therapeutic target for cancer immunotherapy

How can I optimize IHC protocols for APLNR detection in tissue samples?

Based on validated protocols for APLNR antibodies:

• Tissue preparation:

  • Dewax paraffin-embedded sections thoroughly

  • Use citric acid-based antigen retrieval (microwave method recommended)

• Antibody dilution optimization:

  • Start with manufacturer's recommended dilution (typically 1:100 for IHC)

  • Perform titration experiments if necessary (1:50-1:300 range)

• Detection system:

  • Sequential treatment with biotinylated anti-rabbit IgG and avidin-biotin solution has been validated

  • Color development with 3-amino-9-ethylcarbazole (AEC)

  • Counterstain with hematoxylin for nuclear visualization

• Validated tissue controls:

  • Human pancreas has been validated for APLNR expression

  • Human breast cancer, liver cancer, and colon cancer tissues also show detectable expression

What storage conditions maximize APLNR antibody stability and performance?

Proper storage is critical for maintaining antibody activity:

• Long-term storage:

  • Store at -20°C for up to one year

  • Avoid repeated freeze-thaw cycles

• Short-term and working solutions:

  • For frequent use and short-term storage (up to one month), keep at 4°C

• Buffer compositions for stability:

  • Most APLNR antibodies are supplied in PBS containing 50% glycerol

  • Some formulations include stabilizers like 0.5% BSA and 0.02% sodium azide

  • Phosphate buffered solutions (pH 7.4) with stabilizers are common for polyclonal antibodies

• Shipping and receiving considerations:

  • Products typically shipped with ice packs

  • Upon receipt, store immediately at recommended temperature

How can APLNR antibodies be utilized in angiogenesis and invasion studies in cancer models?

APLNR plays a central role in tumor vascularization and invasion, making it valuable for several advanced research applications:

• Glioblastoma angiogenesis models:

  • APLNR antibodies can track changes in receptor expression during antiangiogenic therapy

  • Research shows APLNR signaling controls GBM angiogenesis and invasion

  • Changes in APLNR expression occur in response to VEGFA/VEGFR2 blockade

• Serial implantation models:

  • APLNR antibodies have been used in serial implantation models studying the angiogenic switch in human GBM

  • These models allow tracking of APLNR-positive cell populations during tumor progression

• Combined targeting approaches:

  • Experimental evidence shows co-targeting VEGFR2 and APLNR synergistically improves survival in mice with proneural GBM

  • This suggests APLNR antibodies can help identify optimal combination therapy targets

What are the considerations for using APLNR antibodies in mechanistic studies of cancer immune escape?

Recent research has uncovered APLNR's role in regulating immune escape mechanisms:

• APLNR-JAK1-STAT1-PD-L1 axis:

  • APLNR inhibits PD-L1 expression by binding to the FERM domain of JAK1

  • This binding blocks JAK1-IFNGR1 interaction, suppressing IFN-γ-mediated JAK1/STAT1 pathway activation

  • Antibodies can be used in co-immunoprecipitation studies to confirm these protein-protein interactions

• Experimental approaches:

  • Use APLNR antibodies in immunoprecipitation to pull down associated proteins

  • Follow with Western blot analysis for JAK1, STAT1, and related signaling molecules

  • Combine with functional assays measuring IFN-γ secretion and CD8+ T-cell activity

• Potential therapeutic implications:

  • APLNR expression analysis in cancer tissues may predict response to immunotherapy

  • Combining APLNR targeting with PD-L1 antibody treatment showed enhanced tumor growth inhibition

  • This suggests monitoring APLNR expression could inform immunotherapy strategies