BDKRB2

BDKRB2 encodes a seven-transmembrane G-protein coupled receptor that binds bradykinin with high affinity and constitutes the pharmacologically defined BK-2 receptor subtype (PMID:1314587). Upon activation, the receptor couples to dual calcium signaling: direct intracellular calcium release and a prostaglandin-dependent extracellular calcium influx, the latter driven by receptor-stimulated PGE2 production (PMID:7965750). Through this signaling, BDKRB2 regulates vascular and hemostatic physiology; in its absence, a compensatory angiotensin-(1-7)/Mas axis elevates plasma nitric oxide and prostacyclin, producing a host-environment-dependent platelet function defect and delayed thrombosis (PMID:23386129). In cancer contexts, bradykinin-engaged BDKRB2 drives angiogenesis by upregulating VEGF and promoting endothelial tube formation, effects opposed by the antagonist HOE140 (PMID:31059006), and it acts as a downstream effector of IRX1 repression to promote angiogenesis, vasculogenic mimicry, migration, and invasion via the downstream target PAK1 (PMID:21602894). BDKRB2 expression is positively driven by NMI with concomitant ERK1/2 activation (PMID:28077802) and negatively controlled by miR-129-1-3p targeting its 3'UTR (PMID:25008064). In kidney development, BDKRB2 is a transcriptional target of p53 and engages a feedback loop in which its inactivation upregulates Chk1, potentiating p53-mediated apoptosis under salt stress (PMID:23152407).

1. 1992 High

   Established the molecular identity of the bradykinin BK-2 receptor by cloning and reconstituting a high-affinity, antagonist-sensitive GPCR, resolving what protein mediates BK-2 pharmacology.

   Evidence cDNA cloning, COS-7 transfection, saturation binding and pharmacological characterization with Hoe 140

   PMID:1314587

   Open questions at the time

   • No structural data on the receptor
   • G-protein coupling identity not defined in this study
2. 1994 High

   Defined the gene architecture and chromosomal locus, confirming BDKRB2 as a single-copy three-exon gene at 14q32 and grounding its transcriptional regulation.

   Evidence Genomic library cloning, sequencing, Southern blot, in situ hybridization, RT-PCR

   PMID:7835885

   Open questions at the time

   • Promoter regulatory elements identified only as putative
   • No functional validation of transcription factor binding sites
3. 1994 Medium

   Resolved the downstream signaling logic of the receptor by showing it mobilizes calcium through both intracellular release and a prostaglandin-dependent influx pathway.

   Evidence Calcium imaging with antagonists, calcium-free buffer, indomethacin, and PGE2 measurement in rat myenteric neurons

   PMID:7965750

   Open questions at the time

   • Demonstrated in rat neurons only
   • Specific prostaglandin synthase and effector channels not identified
4. 2011 Medium

   Placed BDKRB2 in an oncogenic transcriptional circuit, showing it acts downstream of IRX1 repression and upstream of PAK1 to drive angiogenesis and invasion.

   Evidence IRX1 overexpression, BDKRB2 and PAK1 siRNA knockdown, angiogenesis, migration, invasion and proliferation assays in gastric cancer

   PMID:21602894

   Open questions at the time

   • Mechanism linking BDKRB2 to PAK1 not defined
   • Single lab, in vitro and chick embryo models
5. 2013 High

   Revealed a non-cell-autonomous role for BDKRB2 in hemostasis, showing receptor loss triggers an angiotensin-(1-7)/Mas-driven NO and prostacyclin elevation that impairs platelets via the host environment.

   Evidence Bdkrb2 knockout mice, pharmacological blockade, reciprocal bone marrow transplantation, platelet function assays, plasma NO/prostacyclin measurement

   PMID:23386129

   Open questions at the time

   • Does not define how chronic receptor loss elevates the Mas axis
   • Human relevance of the platelet phenotype untested
6. 2013 Medium

   Connected BDKRB2 to a p53/Chk1 feedback loop in organogenesis, establishing it as a p53 transcriptional target whose loss potentiates p53-driven apoptosis in the developing kidney.

   Evidence Bdkrb2 knockout mouse with gestational salt stress, analysis of Chk1 levels and p53 Ser23 phosphorylation

   PMID:23152407

   Open questions at the time

   • Direct p53 binding to the Bdkrb2 promoter not shown
   • Mechanism by which receptor loss raises Chk1 unknown
7. 2014 Medium

   Identified a post-transcriptional brake on BDKRB2, with miR-129-1-3p directly targeting its 3'UTR to limit migration.

   Evidence miRNA mimic/inhibitor, luciferase 3'UTR reporter, transwell migration, qRT-PCR in gastric cancer

   PMID:25008064

   Open questions at the time

   • Endogenous miRNA regulation in vivo not assessed
   • Single cancer context
8. 2017 Medium

   Linked an upstream activator to BDKRB2 signaling, showing NMI promotes BDKRB2 expression and ERK1/2 activation to drive HCC proliferation and invasion.

   Evidence NMI knockdown and overexpression, ERK1/2 Western blots, in vitro assays and nude mouse tumor model

   PMID:28077802

   Open questions at the time

   • Mechanism of NMI-driven BDKRB2 upregulation unclear
   • Direct receptor-to-ERK coupling not dissected
9. 2019 Medium

   Defined BDKRB2 as a bradykinin-responsive driver of VEGF-mediated angiogenesis in cancer, with antagonist sensitivity confirming receptor specificity.

   Evidence BK treatment, BDKRB2 knockdown/overexpression, HOE140 antagonist, HUVEC tube formation, VEGF measurement in cervical cancer cells

   PMID:31059006

   Open questions at the time

   • Signaling intermediates between receptor and VEGF not mapped
   • In vitro only

• The G-protein coupling specificity and structural basis of ligand recognition that connect receptor activation to its divergent calcium, ERK, VEGF, and platelet outputs remain unresolved.
• No structural model of the receptor in the corpus
• Heterotrimeric G-protein partners not identified
• Tissue-specific determinants of pathway choice unknown