{"gene":"PROK2","run_date":"2026-04-28T19:45:45","timeline":{"discoveries":[{"year":1999,"finding":"Bv8 (PROK2 amphibian homolog) induces hyperalgesia when injected intracerebroventricularly in rats, acting on receptors present in mammalian brain and intestine, stimulating guinea-pig ileum contraction at nanomolar concentrations.","method":"In vivo injection (i.c.v.) with tail-flick test and paw pressure threshold; in vitro smooth muscle contraction assay","journal":"European journal of pharmacology","confidence":"Medium","confidence_rationale":"Tier 2 — in vivo functional assay with defined behavioral readout, single lab","pmids":["10422759"],"is_preprint":false},{"year":1999,"finding":"Mammalian homologues of Bv8 (PROK2) are most highly expressed in mid-late pachytene spermatocytes of the mouse testis, with two mRNA forms due to alternative splicing.","method":"cDNA cloning, in situ hybridization, developmental expression profiling in mouse testes","journal":"FEBS letters","confidence":"Medium","confidence_rationale":"Tier 2 — direct localization by molecular cloning and expression analysis, single lab","pmids":["10580115"],"is_preprint":false},{"year":2001,"finding":"Mammalian PROK2 (mBv8) is expressed in rodent CNS (cerebral cortex, limbic regions, cerebellar Purkinje cells, spinal cord) and supports neuronal survival by activating the MAPK and PI-3-kinase pathways, protecting cerebellar granule cells and cortical neurons from apoptotic death.","method":"In situ hybridization, immunocytochemistry, in vitro apoptosis assay with PD98059/LY294002 inhibitors, Western blot for phospho-p44/p42 MAPK and phospho-Akt","journal":"The European journal of neuroscience","confidence":"Medium","confidence_rationale":"Tier 2 — multiple orthogonal methods (localization + functional rescue + pathway analysis), single lab","pmids":["11359521"],"is_preprint":false},{"year":2002,"finding":"PROK2 (Bv8) acts on two G-protein coupled prokineticin receptors (PK-R1 and PK-R2) expressed in rat dorsal root ganglia and dorsal spinal cord, inducing Ca2+ elevation in small-diameter nociceptors and causing intense systemic nociceptive sensitization to thermal and mechanical stimuli.","method":"Radioligand binding assay (125I-Bv8), intracellular Ca2+ imaging in DRG neurons, behavioral nociception assays (i.v., s.c., i.t. injection)","journal":"British journal of pharmacology","confidence":"High","confidence_rationale":"Tier 1-2 — binding assay + calcium imaging + in vivo functional assay, moderate evidence across methods","pmids":["12466223"],"is_preprint":false},{"year":2003,"finding":"PROK2 (Bv8) induces proliferation, survival, and migration of adrenal cortical capillary endothelial cells; Bv8/EG-VEGF receptors are localized to vascular endothelial cells in the testis; Bv8 gene expression is induced by hypoxic stress.","method":"Adenoviral delivery to mouse testis, cell proliferation/survival/migration assays, receptor localization by immunohistochemistry","journal":"Proceedings of the National Academy of Sciences of the United States of America","confidence":"High","confidence_rationale":"Tier 1-2 — multiple functional assays (proliferation, migration, survival) plus in vivo adenoviral delivery with angiogenic readout, replicated concept","pmids":["12604792"],"is_preprint":false},{"year":2004,"finding":"PROK2 (Bv8) and its receptors are expressed in hematopoietic stem cells and mature blood cells (monocytes, neutrophils, dendritic cells, lymphocytes); Bv8 stimulates migration of monocytes in a pertussis toxin-sensitive manner, promotes survival and differentiation of granulocytic and monocytic lineages, and increases leukocyte/neutrophil/monocyte counts in vivo.","method":"Systemic in vivo Bv8/EG-VEGF adenoviral delivery, colony-forming unit assays of hematopoietic stem cells, monocyte migration assay (pertussis toxin inhibition), complete blood counts","journal":"Proceedings of the National Academy of Sciences of the United States of America","confidence":"High","confidence_rationale":"Tier 2 — multiple orthogonal in vitro and in vivo assays, replicated across cell types","pmids":["15548611"],"is_preprint":false},{"year":2004,"finding":"PROK2 (Bv8) injected into rat brain lateral ventricles suppresses feeding and stimulates drinking; PK-2 mRNA is expressed in the suprachiasmatic nucleus (SCN) with circadian variation (highest during light phase); PKR-2 is expressed in arcuate nucleus, SCN, and other hypothalamic regions. Bv8 microinjected into the arcuate nucleus selectively suppresses feeding, and into the subfornical organ stimulates drinking.","method":"ICV and microinjection of Bv8 in rats; in situ hybridization for mRNA localization; behavioral assays for feeding and drinking","journal":"British journal of pharmacology","confidence":"Medium","confidence_rationale":"Tier 2 — direct microinjection with site-specific behavioral readout, single lab","pmids":["15066905"],"is_preprint":false},{"year":2005,"finding":"The N-terminal sequence of PROK2 (Bv8), specifically the AVITGA motif, is essential for receptor binding and biological activity; deletion of the first two amino acids (des-AlaVal-Bv8) abolishes biological activity in vitro and in vivo and produces receptor antagonism.","method":"Receptor binding assays, Ca2+ transient assays in CHO cells expressing PKR1/PKR2, MAPK phosphorylation assays, in vivo hyperalgesia assays","journal":"British journal of pharmacology","confidence":"High","confidence_rationale":"Tier 1 — structure-function mutagenesis with multiple in vitro and in vivo readouts","pmids":["16113687"],"is_preprint":false},{"year":2006,"finding":"PROK2 (Bv8) sensitizes TRPV1 (the heat/capsaicin receptor) in dorsal root ganglion nociceptors via a pathway involving PKCε translocation; Bv8 causes Ca2+ increases in capsaicin/bradykinin/mustard oil-responsive DRG neurons through prokineticin receptors. GDNF induces de novo expression of functional prokineticin receptors in non-peptidergic DRG neurons.","method":"Intracellular Ca2+ imaging, PKCε translocation assay, behavioral hyperalgesia assay with PKC antagonists, single-cell RT-PCR, GDNF treatment experiments","journal":"The Journal of neuroscience","confidence":"High","confidence_rationale":"Tier 1-2 — mechanistic pathway dissection with PKCε translocation + pharmacological inhibition + behavioral validation, multiple orthogonal methods","pmids":["16687502"],"is_preprint":false},{"year":2006,"finding":"PROK2 (Bv8) is expressed by macrophages along with PKR1 and PKR2; Bv8 induces potent macrophage chemotaxis (at 10^-12 M) and stimulates LPS-induced IL-1 and IL-12 production while reducing IL-10. These effects are not pertussis-toxin sensitive but are blocked by the phospholipase inhibitor U73122, implicating Gq protein. PKR1 knockout mice studies show all macrophage effects are mediated by PKR1.","method":"Macrophage chemotaxis assay, cytokine ELISA, pharmacological inhibition (pertussis toxin, U73122), PKR1 knockout mice","journal":"British journal of pharmacology","confidence":"High","confidence_rationale":"Tier 2 — genetic KO validation + pharmacological dissection + multiple functional readouts","pmids":["16299550"],"is_preprint":false},{"year":2007,"finding":"In tumors, G-CSF is a major positive regulator of PROK2 (Bv8) expression in CD11b+Gr1+ myeloid cells; Bv8 modulates mobilization of CD11b+Gr1+ cells from bone marrow during tumor development and promotes angiogenesis locally. Anti-Bv8 antibodies reduce myeloid cell mobilization and suppress tumor angiogenesis.","method":"Adenoviral Bv8 delivery to tumors, anti-Bv8 antibody treatment, flow cytometry of myeloid cells, tumor growth/vascular density assays in mice","journal":"Nature","confidence":"High","confidence_rationale":"Tier 2 — multiple genetic and antibody-based experiments with defined cellular and angiogenic readouts, highly cited foundational study","pmids":["18064003"],"is_preprint":false},{"year":2007,"finding":"Intra-PAG PROK2 (Bv8) increases GABA (but not glutamate) extracellular levels in the periaqueductal grey, exerts pronociceptive action, and modulates RVM On-cell and Off-cell activities, consistent with pain facilitation through a GABAergic mechanism.","method":"Intra-PAG microinjection, microdialysis measurement of GABA/glutamate, extracellular single-unit recording of RVM neurons, behavioral thermoceptive reflex tests","journal":"The European journal of neuroscience","confidence":"Medium","confidence_rationale":"Tier 2 — direct microinjection + microdialysis + electrophysiology, single lab","pmids":["18005070"],"is_preprint":false},{"year":2008,"finding":"PROK2 (Bv8) mediates neutrophil-dependent angiogenesis in RIP-Tag transgenic mice; early anti-Bv8 treatment inhibits the angiogenic switch and reduces CD11b+Gr1+ cell mobilization and homing to neoplastic lesions, demonstrating Bv8's role in the early stages of tumor angiogenesis.","method":"Anti-Bv8 antibody treatment in RIP-Tag transgenic mice, histological vascular analysis, flow cytometry","journal":"Proceedings of the National Academy of Sciences of the United States of America","confidence":"High","confidence_rationale":"Tier 2 — transgenic cancer model with antibody blockade + histological + flow cytometric readouts, replicates previous findings in endogenous setting","pmids":["18268320"],"is_preprint":false},{"year":2008,"finding":"PROK2 (Bv8) expression in human neutrophils and bone marrow cells is regulated by G-CSF and GM-CSF; in monocytes and lymphocytes by IL-10. Bv8 potently promotes neutrophil chemotaxis; only PKR2 is detectable in human neutrophils.","method":"Cytokine treatment of isolated human blood cells, RT-PCR, Bv8 partial purification from neutrophils with bioactivity assay, receptor expression analysis","journal":"Clinical cancer research","confidence":"Medium","confidence_rationale":"Tier 2 — multiple cell types, cytokine regulation, and functional chemotaxis assay, single lab","pmids":["19336519"],"is_preprint":false},{"year":2009,"finding":"Granulocyte-derived PROK2 (GrPK2) is the primary mediator of inflammatory pain initiation and peripheral sensitization; PK2 mRNA is up-regulated in granulocytes at sites of inflammation; mice lacking PKR1 or PKR2 develop significantly less inflammation-induced hyperalgesia; PKR1 regulates PK2 levels during inflammation (feedback loop); a non-peptide PKR antagonist abolishes prokineticin-induced hypernociception.","method":"CFA-induced paw inflammation model, PK2 protein purification from peritoneal granulocytes, receptor binding assays, PKR1/PKR2 knockout mice, PKR antagonist treatment, behavioral pain assays","journal":"Proceedings of the National Academy of Sciences of the United States of America","confidence":"High","confidence_rationale":"Tier 1-2 — protein purification + genetic KO + pharmacological antagonism with multiple readouts, strong evidence","pmids":["19667192"],"is_preprint":false},{"year":2010,"finding":"The 3D structure of synthetic Bv8 (PROK2 homolog) was determined by NMR spectroscopy; the protein adopts a structure homologous to mamba intestinal toxin 1. The N-terminal five residues critical for receptor binding do not perturb the core structure when deleted, suggesting receptor binding involves cooperative/allosteric rearrangements.","method":"Chemical synthesis (Boc SPPS + native chemical ligation + in vitro folding), NMR structure determination, functional assays in neuroblastoma cells and rat DRG neurons","journal":"Chembiochem","confidence":"High","confidence_rationale":"Tier 1 — NMR structure + synthetic mutagenesis + functional validation","pmids":["20677202"],"is_preprint":false},{"year":2012,"finding":"G-CSF-induced PROK2 (Bv8) expression in CD11b+Gr1+ myeloid cells requires STAT3 activation; phospho-STAT3 binds the Bv8 promoter (shown by ChIP); siRNA-mediated STAT3 knockdown reduces G-CSF-induced Bv8 expression; this regulation is conserved in human bone marrow cells.","method":"Pharmacological inhibitors of signaling pathways, siRNA knockdown, chromatin immunoprecipitation (ChIP), luciferase reporter assay, in vivo mouse studies","journal":"The Journal of biological chemistry","confidence":"High","confidence_rationale":"Tier 1-2 — ChIP + luciferase + siRNA + in vivo validation, multiple orthogonal methods","pmids":["22528488"],"is_preprint":false},{"year":2012,"finding":"PROK2 (Bv8) induces biphasic hyperalgesia through: (1) direct release of CGRP from spinal cord tissue; (2) a protein-synthesis dependent late phase involving upregulation of CGRP and substance P in lumbar dorsal horn and DRG. Protein synthesis inhibitors block the late but not early phase.","method":"Spinal cord slice CGRP release assay, protein synthesis inhibitor pretreatment, immunohistochemistry for CGRP/substance P, behavioral hyperalgesia assays","journal":"Neuroscience letters","confidence":"Medium","confidence_rationale":"Tier 2 — ex vivo spinal cord assay + pharmacological dissection + immunohistochemistry, single lab","pmids":["22641053"],"is_preprint":false},{"year":2013,"finding":"PROK2 (BV8) activates STAT3 in normal and malignant myeloid cells through JAK2; BV8-induced STAT3 activation regulates genes important for tumor cell proliferation/survival and angiogenesis; BV8 knockdown in human myeloid leukemia cells inhibits STAT3 activity and reduces tumor growth in vivo. A BV8-STAT3 feed-forward loop exists in myeloid cells.","method":"JAK2 genetic and pharmacological inhibition, BV8 shRNA knockdown, tumor xenograft assays, gene expression analysis","journal":"The Journal of biological chemistry","confidence":"High","confidence_rationale":"Tier 2 — genetic + pharmacological JAK2 inhibition + shRNA KD + in vivo tumor model, multiple orthogonal methods","pmids":["23548897"],"is_preprint":false},{"year":2013,"finding":"PROK2/PROKR2 signaling mutations cause Kallmann syndrome through loss-of-function effects including defective cell surface-targeting of the receptor, defective G protein coupling, or impaired receptor-ligand interaction. Homozygous Prok2 and Prokr2 knockout mice have olfactory bulb agenesis/hypoplasia and hypogonadotropic hypogonadism due to failed GnRH neuron migration.","method":"Functional characterization of mutations in transfected cells, Prok2/Prokr2 knockout mouse phenotyping","journal":"Frontiers in endocrinology","confidence":"High","confidence_rationale":"Tier 2 — genetic KO mouse model + cell-based receptor function assays, independently replicated across multiple studies","pmids":["23596439"],"is_preprint":false},{"year":2014,"finding":"PROK2 and its receptor PKR2 are up-regulated in nociceptors, Schwann cells, and activated astrocytes of the spinal cord following chronic sciatic nerve constriction injury; PKR antagonism (PC1) reduces microgliosis, astrocyte activation, restores cytokine balance, and abolishes thermal hyperalgesia and allodynia, demonstrating PROK2 involvement in neuropathic pain through neuron-glia interaction.","method":"Chronic constriction injury mouse model, intrathecal/perineural/s.c. injection of PKR antagonist, immunohistochemistry, cytokine measurement (IL-1β, IL-10), glia activation analysis","journal":"British journal of pharmacology","confidence":"Medium","confidence_rationale":"Tier 2 — pharmacological antagonism + immunohistochemistry + cytokine readouts in established neuropathic pain model, single lab","pmids":["24902717"],"is_preprint":false},{"year":2019,"finding":"PROK2/PROKR2 signaling is required for migration of most olfactory bulb interneurons; Prokr2 is expressed in postmitotic immature interneurons in the SVZ-RMS-OB; in Prok2 and Prokr2 mutant mice, ~75% of GABAergic interneurons in the OB are lost due to severe tangential and radial migration defects of neuroblasts.","method":"Prok2EGFP transgenic and Prokr2LacZ/+ knockin mice, genetic knockout phenotyping, immunofluorescence, cell counting","journal":"The Journal of comparative neurology","confidence":"High","confidence_rationale":"Tier 2 — genetic KO + knockin reporter mouse models with quantitative neuronal migration readout","pmids":["31132148"],"is_preprint":false},{"year":2022,"finding":"The anorexigenic effect of PROK2 is mediated by PKR2 in the amygdala (not hypothalamus); targeted silencing of PKR2 and chemogenetic manipulation of amygdala PKR2 neurons blocks PK2-induced food intake inhibition; MRAP2 expression in PKR2 neurons modulates PK2 signaling activity in vivo.","method":"Targeted PKR2 silencing, DREADD-based chemogenetic manipulation of amygdala PKR2 neurons, MRAP2 overexpression/knockdown, behavioral food intake assays","journal":"The Journal of biological chemistry","confidence":"High","confidence_rationale":"Tier 2 — genetic silencing + chemogenetics with defined circuit-level and behavioral readouts","pmids":["36539034"],"is_preprint":false},{"year":2012,"finding":"PROK2 (Bv8) W24A substitution preferentially binds PKR2 with 5-fold lower potency; des-AlaVal-Bv8 (N-terminal deletion) abolishes receptor activation but retains binding and antagonizes Bv8-induced hyperalgesia; Bv8 modified at W24 (A-24) shows anti-hyperalgesic activity by blocking nociceptor PKR1 receptors and activating central opioid systems via PKR2.","method":"Receptor binding competition assays, Ca2+ mobilization in CHO cells expressing PKR1/PKR2, in vivo hyperalgesia assays, β-endorphin measurement","journal":"British journal of pharmacology","confidence":"Medium","confidence_rationale":"Tier 1 — structure-activity relationship with receptor selectivity dissection + in vivo validation, single lab","pmids":["22122547"],"is_preprint":false},{"year":2016,"finding":"Cutaneous application of PROK2 (Bv8) at nanomolar concentrations sensitizes peripheral unmyelinated polymodal C-fibers to heat by increasing heat-induced discharge, reducing threshold temperature, and increasing heat-induced CGRP release; PROK2 co-localizes with CGRP in plantar skin and nerve. The sensitization is partly but not exclusively through TRPV1.","method":"Single-fiber electrophysiology recordings from cutaneous nerve, CGRP release assay from skin flaps and trigeminal ganglia, immunohistochemistry","journal":"European journal of pain","confidence":"Medium","confidence_rationale":"Tier 2 — single-fiber electrophysiology + CGRP release + co-localization, single lab","pmids":["26914965"],"is_preprint":false},{"year":2020,"finding":"PROK2 activates the AKT/GSK3β signaling pathway via PKR1 and PKR2 receptors to protect cardiomyocytes; the cardioprotective effects of metformin are mediated through the PK2/PKR-AKT/GSK3β pathway, as demonstrated by AKT inhibitor and PKRA7 (PK2 antagonist) blocking these effects in high-glucose-treated cardiomyocytes and diabetic mice.","method":"Western blotting for p-AKT/AKT and p-GSK3β, AKT-knockout mice cardiomyocytes, PKRA7 antagonist treatment, streptozotocin diabetic mouse model","journal":"Frontiers in physiology","confidence":"Medium","confidence_rationale":"Tier 2 — AKT KO + pharmacological antagonist + in vitro/in vivo parallel validation, single lab","pmids":["32508669"],"is_preprint":false},{"year":2024,"finding":"Intracerebroventricular PROK2 infusion increases GnRH mRNA expression in the hypothalamus and elevates serum FSH, LH, and testosterone levels, demonstrating that PROK2 activates the hypothalamic-pituitary-gonadal (HPG) axis.","method":"ICV osmotic mini-pump infusion of PROK2, RT-PCR for GnRH mRNA, ELISA for FSH/LH/testosterone, histological analysis of testicular tissue","journal":"Molecular biology reports","confidence":"Medium","confidence_rationale":"Tier 2 — direct central infusion with molecular and hormonal readouts, single lab","pmids":["38740671"],"is_preprint":false},{"year":2020,"finding":"PROK2 knockdown in HeLa cells significantly inhibits cell migration, invasion, and MMP15 protein expression; PROK2 overexpression reverses these effects and upregulates MMP15, demonstrating that PROK2 promotes cervical cancer invasion by regulating MMP15 expression.","method":"siRNA knockdown, PROK2 overexpression plasmid, migration/invasion assays (transwell), Western blot for MMP15","journal":"International journal of molecular sciences","confidence":"Medium","confidence_rationale":"Tier 2 — reciprocal gain/loss-of-function with defined molecular target (MMP15), single lab","pmids":["32887509"],"is_preprint":false},{"year":2022,"finding":"miR-141-3p targets PBX1, and PBX1 transcriptionally regulates PROK2 expression; inhibition of miR-141-3p reduces NSC apoptosis in MCAO mice through the miR-141-3p/PBX1/PROK2 axis.","method":"Luciferase reporter assay (miR-141-3p targeting PBX1), RT-PCR and Western blot for PROK2 regulation by PBX1, ICV injection of agomir/antagomir in MCAO mice, TUNEL staining","journal":"Cell cycle","confidence":"Medium","confidence_rationale":"Tier 2 — luciferase reporter + gain/loss-of-function + in vivo mouse model, single lab","pmids":["36548024"],"is_preprint":false}],"current_model":"PROK2 (prokineticin 2/Bv8) is a secreted peptide that acts on two G protein-coupled receptors (PKR1/PROKR1 and PKR2/PROKR2) to mediate a broad range of functions: it promotes tissue-restricted angiogenesis and endothelial cell proliferation/survival/migration; mobilizes and recruits CD11b+Gr1+ myeloid cells from bone marrow via a G-CSF/STAT3/JAK2 regulatory axis; sensitizes peripheral nociceptors (TRPV1) through PKCε activation to cause hyperalgesia; guides GnRH neuron migration and olfactory bulb interneuron migration (required for normal reproductive and olfactory development); regulates circadian rhythms and food intake via amygdala PKR2 neurons; activates MAPK and PI3K/AKT/GSK3β pathways to support neuronal and cardiomyocyte survival; and promotes proinflammatory macrophage and neutrophil responses through PKR1-Gq signaling."},"narrative":{"teleology":[{"year":1999,"claim":"Identification of PROK2 (Bv8) as a bioactive secreted peptide established it as a nociceptive and smooth-muscle-active factor expressed in mammalian brain, intestine, and testis.","evidence":"ICV injection with behavioral pain assays in rats; cDNA cloning and in situ hybridization in mouse testes","pmids":["10422759","10580115"],"confidence":"Medium","gaps":["Mammalian receptor identity unknown at this stage","Mechanism of hyperalgesia unresolved","Physiological relevance of testicular expression unclear"]},{"year":2001,"claim":"Demonstration that PROK2 protects neurons from apoptosis via MAPK and PI3K/Akt pathways revealed a neurotrophic function beyond nociception.","evidence":"In vitro apoptosis rescue of cerebellar granule cells with pathway inhibitors (PD98059, LY294002) and phospho-protein Western blots","pmids":["11359521"],"confidence":"Medium","gaps":["In vivo neuroprotective relevance not tested","Receptor subtype mediating survival unclear"]},{"year":2002,"claim":"Identification of PKR1 and PKR2 as PROK2 receptors on nociceptors, with direct calcium mobilization in DRG neurons, provided the molecular basis for PROK2-mediated pain sensitization.","evidence":"Radioligand binding (125I-Bv8) in DRG and spinal cord, calcium imaging in DRG neurons, and behavioral nociception assays","pmids":["12466223"],"confidence":"High","gaps":["Downstream intracellular signaling in nociceptors not dissected","Relative contributions of PKR1 vs PKR2 in pain not resolved"]},{"year":2003,"claim":"Establishing PROK2 as a tissue-selective angiogenic factor that promotes endothelial proliferation, survival, and migration — induced by hypoxia — placed it alongside VEGF as a vascular growth factor with restricted expression.","evidence":"Adenoviral delivery to mouse testis, endothelial cell proliferation/migration/survival assays, receptor immunohistochemistry","pmids":["12604792"],"confidence":"High","gaps":["Whether PROK2 angiogenesis is relevant in pathological settings (tumors) not yet shown","Signaling cascade linking receptors to endothelial responses unknown"]},{"year":2004,"claim":"Discovery that PROK2 acts on hematopoietic cells — promoting monocyte migration via pertussis toxin-sensitive G proteins and increasing leukocyte counts — expanded its role to immune cell regulation, while hypothalamic expression with circadian variation linked it to feeding/drinking behavior.","evidence":"Adenoviral in vivo delivery with CBC counts and colony-forming assays; ICV/microinjection feeding assays; in situ hybridization in SCN","pmids":["15548611","15066905"],"confidence":"High","gaps":["Whether circadian PROK2 rhythm directly drives behavioral outputs vs. acting as an output signal unclear","Brain circuit identity for appetite regulation not resolved"]},{"year":2005,"claim":"Structure–function analysis showing the N-terminal AVITGA motif is essential for receptor activation, and that its deletion creates a receptor antagonist, provided the first pharmacological tools and structural insight into PROK2–receptor interaction.","evidence":"Receptor binding, calcium transients in PKR1/PKR2-expressing CHO cells, MAPK assays, in vivo hyperalgesia with truncated peptides","pmids":["16113687"],"confidence":"High","gaps":["Atomic-level structure of PROK2–receptor complex unknown","Mechanism of antagonism (competitive vs. allosteric) unresolved"]},{"year":2006,"claim":"Mechanistic dissection of PROK2 nociception revealed PKCε translocation as the pathway sensitizing TRPV1, while PROK2 was shown to drive macrophage chemotaxis via PKR1-Gq signaling — not Gi — shifting understanding of receptor coupling in immune cells.","evidence":"PKCε translocation assay + PKC antagonists in DRG neurons; macrophage chemotaxis with U73122 and pertussis toxin; PKR1 knockout mice","pmids":["16687502","16299550"],"confidence":"High","gaps":["Whether PKCε pathway operates in all nociceptor subtypes unclear","Gq-specific signaling intermediates in macrophages not mapped"]},{"year":2007,"claim":"The demonstration that G-CSF drives PROK2 expression in tumor-infiltrating CD11b+Gr1+ myeloid cells and that anti-Bv8 antibodies suppress myeloid mobilization and tumor angiogenesis established PROK2 as a key mediator linking innate immunity to tumor vasculature.","evidence":"Anti-Bv8 antibody treatment in tumor-bearing mice, flow cytometry of myeloid cells, vascular density analysis; confirmed in RIP-Tag transgenic model","pmids":["18064003","18268320"],"confidence":"High","gaps":["Direct versus indirect effects on endothelial cells in tumors not fully dissected","Whether anti-Bv8 is effective in established (late-stage) tumors remains uncertain"]},{"year":2009,"claim":"Genetic knockout of PKR1 and PKR2 proved that granulocyte-derived PROK2 is the primary initiator of inflammatory pain; a PKR1-dependent feedback loop regulating PROK2 levels was uncovered, and a small-molecule PKR antagonist achieved analgesia.","evidence":"CFA inflammation model in PKR1/PKR2 KO mice, PROK2 purification from granulocytes, non-peptide antagonist treatment","pmids":["19667192"],"confidence":"High","gaps":["Molecular identity of non-peptide antagonist target specificity not fully characterized","Contribution of neuronal vs. immune cell PROK2 not resolved"]},{"year":2010,"claim":"Determination of the 3D NMR structure of Bv8 revealed a colipase/mamba-toxin fold and showed that N-terminal residues critical for receptor activation are flexible and do not alter the core structure, suggesting an allosteric binding mechanism.","evidence":"Chemical synthesis, NMR spectroscopy, functional validation in neuroblastoma cells and DRG neurons","pmids":["20677202"],"confidence":"High","gaps":["No receptor-bound co-structure available","How N-terminal flexibility translates to receptor activation mechanistically unknown"]},{"year":2012,"claim":"G-CSF-induced PROK2 expression was shown to require STAT3 binding directly to the Bv8 promoter, completing the transcriptional mechanism linking tumor-derived G-CSF to myeloid PROK2 upregulation; concurrently, receptor-selective Bv8 analogs demonstrated differential PKR1/PKR2 contributions to pain modulation.","evidence":"ChIP for pSTAT3 at Bv8 promoter, luciferase reporter, siRNA knockdown; W24A Bv8 binding/calcium assays and in vivo hyperalgesia with β-endorphin measurement","pmids":["22528488","22122547"],"confidence":"High","gaps":["Whether STAT3 is sufficient or requires co-factors for Bv8 transcription unknown","Central opioid activation via PKR2 pathway not fully mapped"]},{"year":2013,"claim":"Discovery of a BV8–JAK2–STAT3 feed-forward loop in myeloid leukemia cells, where PROK2 both activates and is transcriptionally induced by STAT3, provided a mechanistic basis for autocrine amplification in tumor-associated myeloid cells; simultaneously, loss-of-function mutations in PROK2/PROKR2 were definitively linked to Kallmann syndrome through defective GnRH neuron migration.","evidence":"JAK2 inhibition + BV8 shRNA in leukemia xenografts; Prok2/Prokr2 KO mouse phenotyping with olfactory bulb and GnRH analyses; patient mutation functional characterization","pmids":["23548897","23596439"],"confidence":"High","gaps":["Whether the feed-forward loop operates in non-myeloid tumors unclear","Molecular mechanism of GnRH neuron guidance by PROK2 gradient not resolved"]},{"year":2019,"claim":"Quantitative analysis in Prok2 and Prokr2 mutant mice revealed that ~75% of GABAergic olfactory bulb interneurons require PROK2/PROKR2 for tangential and radial migration from the SVZ-RMS, establishing PROK2 as a dominant guidance cue for postnatal interneuron migration.","evidence":"Prok2-EGFP and Prokr2-LacZ knockin reporters, genetic KO phenotyping with immunofluorescence and cell counting","pmids":["31132148"],"confidence":"High","gaps":["Downstream cytoskeletal effectors in migrating neuroblasts unknown","Whether PROK2 acts as chemoattractant versus motogen in this context unresolved"]},{"year":2020,"claim":"PROK2 was shown to activate AKT/GSK3β signaling for cardiomyocyte protection and to promote cervical cancer cell invasion via MMP15 upregulation, extending its functional repertoire to cardiac and oncological contexts.","evidence":"AKT KO cardiomyocytes + PKRA7 antagonist in diabetic mice; PROK2 siRNA/overexpression in HeLa cells with transwell invasion assays","pmids":["32508669","32887509"],"confidence":"Medium","gaps":["Transcriptional mechanism linking PROK2 to MMP15 not identified","Whether cardiomyocyte effects are receptor subtype-specific not resolved","Single-lab findings for each"]},{"year":2022,"claim":"Circuit-level dissection showed that PROK2's anorexigenic action is mediated specifically by PKR2 neurons in the amygdala — not hypothalamus — with MRAP2 acting as a modulator of receptor signaling, resolving the anatomical locus of PROK2 appetite suppression.","evidence":"Targeted PKR2 silencing and DREADD chemogenetic manipulation of amygdala neurons; MRAP2 overexpression/knockdown with behavioral food intake assays","pmids":["36539034"],"confidence":"High","gaps":["Downstream amygdala circuits mediating anorexia not mapped","Whether MRAP2 modulation is specific to amygdala PKR2 neurons unclear"]},{"year":2024,"claim":"Central PROK2 infusion was shown to activate the hypothalamic-pituitary-gonadal axis by increasing GnRH mRNA and elevating FSH, LH, and testosterone, providing direct evidence that PROK2 is an upstream regulator of reproductive hormone release.","evidence":"ICV osmotic mini-pump infusion with RT-PCR for GnRH and ELISA for gonadotropins/testosterone","pmids":["38740671"],"confidence":"Medium","gaps":["Whether the effect is mediated by direct action on GnRH neurons vs. intermediate neurons unknown","Receptor subtype mediating HPG activation not identified","Single-lab study"]},{"year":null,"claim":"Key unresolved questions include the atomic structure of PROK2 bound to PKR1 or PKR2, the molecular basis for receptor subtype selectivity in different tissues, and the intracellular signaling cascades linking PROK2 to cytoskeletal rearrangements during neuronal migration.","evidence":"","pmids":[],"confidence":"Low","gaps":["No co-crystal or cryo-EM structure of PROK2–receptor complex","Receptor subtype-specific signaling pathways in neuronal migration undefined","In vivo redundancy between PKR1 and PKR2 in most physiological contexts not systematically addressed"]}],"mechanism_profile":{"molecular_activity":[{"term_id":"GO:0048018","term_label":"receptor ligand activity","supporting_discovery_ids":[3,7,8,9,15]}],"localization":[{"term_id":"GO:0005576","term_label":"extracellular region","supporting_discovery_ids":[0,4,5,10,14]}],"pathway":[{"term_id":"R-HSA-162582","term_label":"Signal Transduction","supporting_discovery_ids":[2,3,8,18,25]},{"term_id":"R-HSA-168256","term_label":"Immune System","supporting_discovery_ids":[5,9,10,13,14]},{"term_id":"R-HSA-112316","term_label":"Neuronal System","supporting_discovery_ids":[2,6,11,19,21]},{"term_id":"R-HSA-1266738","term_label":"Developmental Biology","supporting_discovery_ids":[19,21,26]}],"complexes":[],"partners":["PROKR1","PROKR2","TRPV1","STAT3","CSF3","MRAP2","JAK2","MMP15"],"other_free_text":[]},"mechanistic_narrative":"PROK2 (prokineticin 2/Bv8) is a secreted cysteine-rich peptide that signals through two G protein-coupled receptors (PKR1/PROKR1 and PKR2/PROKR2) to regulate pain sensitization, angiogenesis, immune cell mobilization, neuronal migration, circadian feeding behavior, and reproductive axis function. In nociceptive pathways, PROK2 sensitizes peripheral C-fibers and TRPV1 via PKCε translocation, induces CGRP release from spinal cord, and activates GABAergic pronociceptive circuits in the periaqueductal grey; granulocyte-derived PROK2 is a primary mediator of inflammatory pain, as demonstrated by abolished hyperalgesia in PKR1/PKR2 knockout mice [PMID:19667192, PMID:16687502, PMID:26914965]. In the tumor microenvironment, G-CSF drives PROK2 expression in CD11b+Gr1+ myeloid cells via STAT3 binding to the Bv8 promoter, and PROK2 in turn promotes myeloid mobilization from bone marrow and tumor angiogenesis through a BV8–STAT3–JAK2 feed-forward loop [PMID:18064003, PMID:22528488, PMID:23548897]. Loss-of-function mutations in PROK2 or PROKR2 cause Kallmann syndrome, characterized by olfactory bulb agenesis and hypogonadotropic hypogonadism due to defective GnRH neuron and olfactory bulb interneuron migration [PMID:23596439, PMID:31132148]."},"prefetch_data":{"uniprot":{"accession":"Q9HC23","full_name":"Prokineticin-2","aliases":["Protein Bv8 homolog"],"length_aa":129,"mass_kda":14.3,"function":"May function as an output molecule from the suprachiasmatic nucleus (SCN) that transmits behavioral circadian rhythm. May also function locally within the SCN to synchronize output. 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in vitro smooth muscle contraction assay\",\n      \"journal\": \"European journal of pharmacology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — in vivo functional assay with defined behavioral readout, single lab\",\n      \"pmids\": [\"10422759\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 1999,\n      \"finding\": \"Mammalian homologues of Bv8 (PROK2) are most highly expressed in mid-late pachytene spermatocytes of the mouse testis, with two mRNA forms due to alternative splicing.\",\n      \"method\": \"cDNA cloning, in situ hybridization, developmental expression profiling in mouse testes\",\n      \"journal\": \"FEBS letters\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — direct localization by molecular cloning and expression analysis, single lab\",\n      \"pmids\": [\"10580115\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2001,\n      \"finding\": \"Mammalian PROK2 (mBv8) is expressed in rodent CNS (cerebral cortex, limbic regions, cerebellar Purkinje cells, spinal cord) and supports neuronal survival by activating the MAPK and PI-3-kinase pathways, protecting cerebellar granule cells and cortical neurons from apoptotic death.\",\n      \"method\": \"In situ hybridization, immunocytochemistry, in vitro apoptosis assay with PD98059/LY294002 inhibitors, Western blot for phospho-p44/p42 MAPK and phospho-Akt\",\n      \"journal\": \"The European journal of neuroscience\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — multiple orthogonal methods (localization + functional rescue + pathway analysis), single lab\",\n      \"pmids\": [\"11359521\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2002,\n      \"finding\": \"PROK2 (Bv8) acts on two G-protein coupled prokineticin receptors (PK-R1 and PK-R2) expressed in rat dorsal root ganglia and dorsal spinal cord, inducing Ca2+ elevation in small-diameter nociceptors and causing intense systemic nociceptive sensitization to thermal and mechanical stimuli.\",\n      \"method\": \"Radioligand binding assay (125I-Bv8), intracellular Ca2+ imaging in DRG neurons, behavioral nociception assays (i.v., s.c., i.t. injection)\",\n      \"journal\": \"British journal of pharmacology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1-2 — binding assay + calcium imaging + in vivo functional assay, moderate evidence across methods\",\n      \"pmids\": [\"12466223\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2003,\n      \"finding\": \"PROK2 (Bv8) induces proliferation, survival, and migration of adrenal cortical capillary endothelial cells; Bv8/EG-VEGF receptors are localized to vascular endothelial cells in the testis; Bv8 gene expression is induced by hypoxic stress.\",\n      \"method\": \"Adenoviral delivery to mouse testis, cell proliferation/survival/migration assays, receptor localization by immunohistochemistry\",\n      \"journal\": \"Proceedings of the National Academy of Sciences of the United States of America\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1-2 — multiple functional assays (proliferation, migration, survival) plus in vivo adenoviral delivery with angiogenic readout, replicated concept\",\n      \"pmids\": [\"12604792\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2004,\n      \"finding\": \"PROK2 (Bv8) and its receptors are expressed in hematopoietic stem cells and mature blood cells (monocytes, neutrophils, dendritic cells, lymphocytes); Bv8 stimulates migration of monocytes in a pertussis toxin-sensitive manner, promotes survival and differentiation of granulocytic and monocytic lineages, and increases leukocyte/neutrophil/monocyte counts in vivo.\",\n      \"method\": \"Systemic in vivo Bv8/EG-VEGF adenoviral delivery, colony-forming unit assays of hematopoietic stem cells, monocyte migration assay (pertussis toxin inhibition), complete blood counts\",\n      \"journal\": \"Proceedings of the National Academy of Sciences of the United States of America\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — multiple orthogonal in vitro and in vivo assays, replicated across cell types\",\n      \"pmids\": [\"15548611\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2004,\n      \"finding\": \"PROK2 (Bv8) injected into rat brain lateral ventricles suppresses feeding and stimulates drinking; PK-2 mRNA is expressed in the suprachiasmatic nucleus (SCN) with circadian variation (highest during light phase); PKR-2 is expressed in arcuate nucleus, SCN, and other hypothalamic regions. Bv8 microinjected into the arcuate nucleus selectively suppresses feeding, and into the subfornical organ stimulates drinking.\",\n      \"method\": \"ICV and microinjection of Bv8 in rats; in situ hybridization for mRNA localization; behavioral assays for feeding and drinking\",\n      \"journal\": \"British journal of pharmacology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — direct microinjection with site-specific behavioral readout, single lab\",\n      \"pmids\": [\"15066905\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2005,\n      \"finding\": \"The N-terminal sequence of PROK2 (Bv8), specifically the AVITGA motif, is essential for receptor binding and biological activity; deletion of the first two amino acids (des-AlaVal-Bv8) abolishes biological activity in vitro and in vivo and produces receptor antagonism.\",\n      \"method\": \"Receptor binding assays, Ca2+ transient assays in CHO cells expressing PKR1/PKR2, MAPK phosphorylation assays, in vivo hyperalgesia assays\",\n      \"journal\": \"British journal of pharmacology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 — structure-function mutagenesis with multiple in vitro and in vivo readouts\",\n      \"pmids\": [\"16113687\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2006,\n      \"finding\": \"PROK2 (Bv8) sensitizes TRPV1 (the heat/capsaicin receptor) in dorsal root ganglion nociceptors via a pathway involving PKCε translocation; Bv8 causes Ca2+ increases in capsaicin/bradykinin/mustard oil-responsive DRG neurons through prokineticin receptors. GDNF induces de novo expression of functional prokineticin receptors in non-peptidergic DRG neurons.\",\n      \"method\": \"Intracellular Ca2+ imaging, PKCε translocation assay, behavioral hyperalgesia assay with PKC antagonists, single-cell RT-PCR, GDNF treatment experiments\",\n      \"journal\": \"The Journal of neuroscience\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1-2 — mechanistic pathway dissection with PKCε translocation + pharmacological inhibition + behavioral validation, multiple orthogonal methods\",\n      \"pmids\": [\"16687502\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2006,\n      \"finding\": \"PROK2 (Bv8) is expressed by macrophages along with PKR1 and PKR2; Bv8 induces potent macrophage chemotaxis (at 10^-12 M) and stimulates LPS-induced IL-1 and IL-12 production while reducing IL-10. These effects are not pertussis-toxin sensitive but are blocked by the phospholipase inhibitor U73122, implicating Gq protein. PKR1 knockout mice studies show all macrophage effects are mediated by PKR1.\",\n      \"method\": \"Macrophage chemotaxis assay, cytokine ELISA, pharmacological inhibition (pertussis toxin, U73122), PKR1 knockout mice\",\n      \"journal\": \"British journal of pharmacology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — genetic KO validation + pharmacological dissection + multiple functional readouts\",\n      \"pmids\": [\"16299550\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2007,\n      \"finding\": \"In tumors, G-CSF is a major positive regulator of PROK2 (Bv8) expression in CD11b+Gr1+ myeloid cells; Bv8 modulates mobilization of CD11b+Gr1+ cells from bone marrow during tumor development and promotes angiogenesis locally. Anti-Bv8 antibodies reduce myeloid cell mobilization and suppress tumor angiogenesis.\",\n      \"method\": \"Adenoviral Bv8 delivery to tumors, anti-Bv8 antibody treatment, flow cytometry of myeloid cells, tumor growth/vascular density assays in mice\",\n      \"journal\": \"Nature\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — multiple genetic and antibody-based experiments with defined cellular and angiogenic readouts, highly cited foundational study\",\n      \"pmids\": [\"18064003\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2007,\n      \"finding\": \"Intra-PAG PROK2 (Bv8) increases GABA (but not glutamate) extracellular levels in the periaqueductal grey, exerts pronociceptive action, and modulates RVM On-cell and Off-cell activities, consistent with pain facilitation through a GABAergic mechanism.\",\n      \"method\": \"Intra-PAG microinjection, microdialysis measurement of GABA/glutamate, extracellular single-unit recording of RVM neurons, behavioral thermoceptive reflex tests\",\n      \"journal\": \"The European journal of neuroscience\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — direct microinjection + microdialysis + electrophysiology, single lab\",\n      \"pmids\": [\"18005070\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2008,\n      \"finding\": \"PROK2 (Bv8) mediates neutrophil-dependent angiogenesis in RIP-Tag transgenic mice; early anti-Bv8 treatment inhibits the angiogenic switch and reduces CD11b+Gr1+ cell mobilization and homing to neoplastic lesions, demonstrating Bv8's role in the early stages of tumor angiogenesis.\",\n      \"method\": \"Anti-Bv8 antibody treatment in RIP-Tag transgenic mice, histological vascular analysis, flow cytometry\",\n      \"journal\": \"Proceedings of the National Academy of Sciences of the United States of America\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — transgenic cancer model with antibody blockade + histological + flow cytometric readouts, replicates previous findings in endogenous setting\",\n      \"pmids\": [\"18268320\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2008,\n      \"finding\": \"PROK2 (Bv8) expression in human neutrophils and bone marrow cells is regulated by G-CSF and GM-CSF; in monocytes and lymphocytes by IL-10. Bv8 potently promotes neutrophil chemotaxis; only PKR2 is detectable in human neutrophils.\",\n      \"method\": \"Cytokine treatment of isolated human blood cells, RT-PCR, Bv8 partial purification from neutrophils with bioactivity assay, receptor expression analysis\",\n      \"journal\": \"Clinical cancer research\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — multiple cell types, cytokine regulation, and functional chemotaxis assay, single lab\",\n      \"pmids\": [\"19336519\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2009,\n      \"finding\": \"Granulocyte-derived PROK2 (GrPK2) is the primary mediator of inflammatory pain initiation and peripheral sensitization; PK2 mRNA is up-regulated in granulocytes at sites of inflammation; mice lacking PKR1 or PKR2 develop significantly less inflammation-induced hyperalgesia; PKR1 regulates PK2 levels during inflammation (feedback loop); a non-peptide PKR antagonist abolishes prokineticin-induced hypernociception.\",\n      \"method\": \"CFA-induced paw inflammation model, PK2 protein purification from peritoneal granulocytes, receptor binding assays, PKR1/PKR2 knockout mice, PKR antagonist treatment, behavioral pain assays\",\n      \"journal\": \"Proceedings of the National Academy of Sciences of the United States of America\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1-2 — protein purification + genetic KO + pharmacological antagonism with multiple readouts, strong evidence\",\n      \"pmids\": [\"19667192\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2010,\n      \"finding\": \"The 3D structure of synthetic Bv8 (PROK2 homolog) was determined by NMR spectroscopy; the protein adopts a structure homologous to mamba intestinal toxin 1. The N-terminal five residues critical for receptor binding do not perturb the core structure when deleted, suggesting receptor binding involves cooperative/allosteric rearrangements.\",\n      \"method\": \"Chemical synthesis (Boc SPPS + native chemical ligation + in vitro folding), NMR structure determination, functional assays in neuroblastoma cells and rat DRG neurons\",\n      \"journal\": \"Chembiochem\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 — NMR structure + synthetic mutagenesis + functional validation\",\n      \"pmids\": [\"20677202\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2012,\n      \"finding\": \"G-CSF-induced PROK2 (Bv8) expression in CD11b+Gr1+ myeloid cells requires STAT3 activation; phospho-STAT3 binds the Bv8 promoter (shown by ChIP); siRNA-mediated STAT3 knockdown reduces G-CSF-induced Bv8 expression; this regulation is conserved in human bone marrow cells.\",\n      \"method\": \"Pharmacological inhibitors of signaling pathways, siRNA knockdown, chromatin immunoprecipitation (ChIP), luciferase reporter assay, in vivo mouse studies\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1-2 — ChIP + luciferase + siRNA + in vivo validation, multiple orthogonal methods\",\n      \"pmids\": [\"22528488\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2012,\n      \"finding\": \"PROK2 (Bv8) induces biphasic hyperalgesia through: (1) direct release of CGRP from spinal cord tissue; (2) a protein-synthesis dependent late phase involving upregulation of CGRP and substance P in lumbar dorsal horn and DRG. Protein synthesis inhibitors block the late but not early phase.\",\n      \"method\": \"Spinal cord slice CGRP release assay, protein synthesis inhibitor pretreatment, immunohistochemistry for CGRP/substance P, behavioral hyperalgesia assays\",\n      \"journal\": \"Neuroscience letters\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — ex vivo spinal cord assay + pharmacological dissection + immunohistochemistry, single lab\",\n      \"pmids\": [\"22641053\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2013,\n      \"finding\": \"PROK2 (BV8) activates STAT3 in normal and malignant myeloid cells through JAK2; BV8-induced STAT3 activation regulates genes important for tumor cell proliferation/survival and angiogenesis; BV8 knockdown in human myeloid leukemia cells inhibits STAT3 activity and reduces tumor growth in vivo. A BV8-STAT3 feed-forward loop exists in myeloid cells.\",\n      \"method\": \"JAK2 genetic and pharmacological inhibition, BV8 shRNA knockdown, tumor xenograft assays, gene expression analysis\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — genetic + pharmacological JAK2 inhibition + shRNA KD + in vivo tumor model, multiple orthogonal methods\",\n      \"pmids\": [\"23548897\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2013,\n      \"finding\": \"PROK2/PROKR2 signaling mutations cause Kallmann syndrome through loss-of-function effects including defective cell surface-targeting of the receptor, defective G protein coupling, or impaired receptor-ligand interaction. Homozygous Prok2 and Prokr2 knockout mice have olfactory bulb agenesis/hypoplasia and hypogonadotropic hypogonadism due to failed GnRH neuron migration.\",\n      \"method\": \"Functional characterization of mutations in transfected cells, Prok2/Prokr2 knockout mouse phenotyping\",\n      \"journal\": \"Frontiers in endocrinology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — genetic KO mouse model + cell-based receptor function assays, independently replicated across multiple studies\",\n      \"pmids\": [\"23596439\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2014,\n      \"finding\": \"PROK2 and its receptor PKR2 are up-regulated in nociceptors, Schwann cells, and activated astrocytes of the spinal cord following chronic sciatic nerve constriction injury; PKR antagonism (PC1) reduces microgliosis, astrocyte activation, restores cytokine balance, and abolishes thermal hyperalgesia and allodynia, demonstrating PROK2 involvement in neuropathic pain through neuron-glia interaction.\",\n      \"method\": \"Chronic constriction injury mouse model, intrathecal/perineural/s.c. injection of PKR antagonist, immunohistochemistry, cytokine measurement (IL-1β, IL-10), glia activation analysis\",\n      \"journal\": \"British journal of pharmacology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — pharmacological antagonism + immunohistochemistry + cytokine readouts in established neuropathic pain model, single lab\",\n      \"pmids\": [\"24902717\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2019,\n      \"finding\": \"PROK2/PROKR2 signaling is required for migration of most olfactory bulb interneurons; Prokr2 is expressed in postmitotic immature interneurons in the SVZ-RMS-OB; in Prok2 and Prokr2 mutant mice, ~75% of GABAergic interneurons in the OB are lost due to severe tangential and radial migration defects of neuroblasts.\",\n      \"method\": \"Prok2EGFP transgenic and Prokr2LacZ/+ knockin mice, genetic knockout phenotyping, immunofluorescence, cell counting\",\n      \"journal\": \"The Journal of comparative neurology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — genetic KO + knockin reporter mouse models with quantitative neuronal migration readout\",\n      \"pmids\": [\"31132148\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2022,\n      \"finding\": \"The anorexigenic effect of PROK2 is mediated by PKR2 in the amygdala (not hypothalamus); targeted silencing of PKR2 and chemogenetic manipulation of amygdala PKR2 neurons blocks PK2-induced food intake inhibition; MRAP2 expression in PKR2 neurons modulates PK2 signaling activity in vivo.\",\n      \"method\": \"Targeted PKR2 silencing, DREADD-based chemogenetic manipulation of amygdala PKR2 neurons, MRAP2 overexpression/knockdown, behavioral food intake assays\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — genetic silencing + chemogenetics with defined circuit-level and behavioral readouts\",\n      \"pmids\": [\"36539034\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2012,\n      \"finding\": \"PROK2 (Bv8) W24A substitution preferentially binds PKR2 with 5-fold lower potency; des-AlaVal-Bv8 (N-terminal deletion) abolishes receptor activation but retains binding and antagonizes Bv8-induced hyperalgesia; Bv8 modified at W24 (A-24) shows anti-hyperalgesic activity by blocking nociceptor PKR1 receptors and activating central opioid systems via PKR2.\",\n      \"method\": \"Receptor binding competition assays, Ca2+ mobilization in CHO cells expressing PKR1/PKR2, in vivo hyperalgesia assays, β-endorphin measurement\",\n      \"journal\": \"British journal of pharmacology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 1 — structure-activity relationship with receptor selectivity dissection + in vivo validation, single lab\",\n      \"pmids\": [\"22122547\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2016,\n      \"finding\": \"Cutaneous application of PROK2 (Bv8) at nanomolar concentrations sensitizes peripheral unmyelinated polymodal C-fibers to heat by increasing heat-induced discharge, reducing threshold temperature, and increasing heat-induced CGRP release; PROK2 co-localizes with CGRP in plantar skin and nerve. The sensitization is partly but not exclusively through TRPV1.\",\n      \"method\": \"Single-fiber electrophysiology recordings from cutaneous nerve, CGRP release assay from skin flaps and trigeminal ganglia, immunohistochemistry\",\n      \"journal\": \"European journal of pain\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — single-fiber electrophysiology + CGRP release + co-localization, single lab\",\n      \"pmids\": [\"26914965\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2020,\n      \"finding\": \"PROK2 activates the AKT/GSK3β signaling pathway via PKR1 and PKR2 receptors to protect cardiomyocytes; the cardioprotective effects of metformin are mediated through the PK2/PKR-AKT/GSK3β pathway, as demonstrated by AKT inhibitor and PKRA7 (PK2 antagonist) blocking these effects in high-glucose-treated cardiomyocytes and diabetic mice.\",\n      \"method\": \"Western blotting for p-AKT/AKT and p-GSK3β, AKT-knockout mice cardiomyocytes, PKRA7 antagonist treatment, streptozotocin diabetic mouse model\",\n      \"journal\": \"Frontiers in physiology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — AKT KO + pharmacological antagonist + in vitro/in vivo parallel validation, single lab\",\n      \"pmids\": [\"32508669\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2024,\n      \"finding\": \"Intracerebroventricular PROK2 infusion increases GnRH mRNA expression in the hypothalamus and elevates serum FSH, LH, and testosterone levels, demonstrating that PROK2 activates the hypothalamic-pituitary-gonadal (HPG) axis.\",\n      \"method\": \"ICV osmotic mini-pump infusion of PROK2, RT-PCR for GnRH mRNA, ELISA for FSH/LH/testosterone, histological analysis of testicular tissue\",\n      \"journal\": \"Molecular biology reports\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — direct central infusion with molecular and hormonal readouts, single lab\",\n      \"pmids\": [\"38740671\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2020,\n      \"finding\": \"PROK2 knockdown in HeLa cells significantly inhibits cell migration, invasion, and MMP15 protein expression; PROK2 overexpression reverses these effects and upregulates MMP15, demonstrating that PROK2 promotes cervical cancer invasion by regulating MMP15 expression.\",\n      \"method\": \"siRNA knockdown, PROK2 overexpression plasmid, migration/invasion assays (transwell), Western blot for MMP15\",\n      \"journal\": \"International journal of molecular sciences\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — reciprocal gain/loss-of-function with defined molecular target (MMP15), single lab\",\n      \"pmids\": [\"32887509\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2022,\n      \"finding\": \"miR-141-3p targets PBX1, and PBX1 transcriptionally regulates PROK2 expression; inhibition of miR-141-3p reduces NSC apoptosis in MCAO mice through the miR-141-3p/PBX1/PROK2 axis.\",\n      \"method\": \"Luciferase reporter assay (miR-141-3p targeting PBX1), RT-PCR and Western blot for PROK2 regulation by PBX1, ICV injection of agomir/antagomir in MCAO mice, TUNEL staining\",\n      \"journal\": \"Cell cycle\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — luciferase reporter + gain/loss-of-function + in vivo mouse model, single lab\",\n      \"pmids\": [\"36548024\"],\n      \"is_preprint\": false\n    }\n  ],\n  \"current_model\": \"PROK2 (prokineticin 2/Bv8) is a secreted peptide that acts on two G protein-coupled receptors (PKR1/PROKR1 and PKR2/PROKR2) to mediate a broad range of functions: it promotes tissue-restricted angiogenesis and endothelial cell proliferation/survival/migration; mobilizes and recruits CD11b+Gr1+ myeloid cells from bone marrow via a G-CSF/STAT3/JAK2 regulatory axis; sensitizes peripheral nociceptors (TRPV1) through PKCε activation to cause hyperalgesia; guides GnRH neuron migration and olfactory bulb interneuron migration (required for normal reproductive and olfactory development); regulates circadian rhythms and food intake via amygdala PKR2 neurons; activates MAPK and PI3K/AKT/GSK3β pathways to support neuronal and cardiomyocyte survival; and promotes proinflammatory macrophage and neutrophil responses through PKR1-Gq signaling.\"\n}\n```","stage2_raw":"```json\n{\n  \"mechanistic_narrative\": \"PROK2 (prokineticin 2/Bv8) is a secreted cysteine-rich peptide that signals through two G protein-coupled receptors (PKR1/PROKR1 and PKR2/PROKR2) to regulate pain sensitization, angiogenesis, immune cell mobilization, neuronal migration, circadian feeding behavior, and reproductive axis function. In nociceptive pathways, PROK2 sensitizes peripheral C-fibers and TRPV1 via PKCε translocation, induces CGRP release from spinal cord, and activates GABAergic pronociceptive circuits in the periaqueductal grey; granulocyte-derived PROK2 is a primary mediator of inflammatory pain, as demonstrated by abolished hyperalgesia in PKR1/PKR2 knockout mice [PMID:19667192, PMID:16687502, PMID:26914965]. In the tumor microenvironment, G-CSF drives PROK2 expression in CD11b+Gr1+ myeloid cells via STAT3 binding to the Bv8 promoter, and PROK2 in turn promotes myeloid mobilization from bone marrow and tumor angiogenesis through a BV8–STAT3–JAK2 feed-forward loop [PMID:18064003, PMID:22528488, PMID:23548897]. Loss-of-function mutations in PROK2 or PROKR2 cause Kallmann syndrome, characterized by olfactory bulb agenesis and hypogonadotropic hypogonadism due to defective GnRH neuron and olfactory bulb interneuron migration [PMID:23596439, PMID:31132148].\",\n  \"teleology\": [\n    {\n      \"year\": 1999,\n      \"claim\": \"Identification of PROK2 (Bv8) as a bioactive secreted peptide established it as a nociceptive and smooth-muscle-active factor expressed in mammalian brain, intestine, and testis.\",\n      \"evidence\": \"ICV injection with behavioral pain assays in rats; cDNA cloning and in situ hybridization in mouse testes\",\n      \"pmids\": [\"10422759\", \"10580115\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Mammalian receptor identity unknown at this stage\", \"Mechanism of hyperalgesia unresolved\", \"Physiological relevance of testicular expression unclear\"]\n    },\n    {\n      \"year\": 2001,\n      \"claim\": \"Demonstration that PROK2 protects neurons from apoptosis via MAPK and PI3K/Akt pathways revealed a neurotrophic function beyond nociception.\",\n      \"evidence\": \"In vitro apoptosis rescue of cerebellar granule cells with pathway inhibitors (PD98059, LY294002) and phospho-protein Western blots\",\n      \"pmids\": [\"11359521\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"In vivo neuroprotective relevance not tested\", \"Receptor subtype mediating survival unclear\"]\n    },\n    {\n      \"year\": 2002,\n      \"claim\": \"Identification of PKR1 and PKR2 as PROK2 receptors on nociceptors, with direct calcium mobilization in DRG neurons, provided the molecular basis for PROK2-mediated pain sensitization.\",\n      \"evidence\": \"Radioligand binding (125I-Bv8) in DRG and spinal cord, calcium imaging in DRG neurons, and behavioral nociception assays\",\n      \"pmids\": [\"12466223\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Downstream intracellular signaling in nociceptors not dissected\", \"Relative contributions of PKR1 vs PKR2 in pain not resolved\"]\n    },\n    {\n      \"year\": 2003,\n      \"claim\": \"Establishing PROK2 as a tissue-selective angiogenic factor that promotes endothelial proliferation, survival, and migration — induced by hypoxia — placed it alongside VEGF as a vascular growth factor with restricted expression.\",\n      \"evidence\": \"Adenoviral delivery to mouse testis, endothelial cell proliferation/migration/survival assays, receptor immunohistochemistry\",\n      \"pmids\": [\"12604792\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Whether PROK2 angiogenesis is relevant in pathological settings (tumors) not yet shown\", \"Signaling cascade linking receptors to endothelial responses unknown\"]\n    },\n    {\n      \"year\": 2004,\n      \"claim\": \"Discovery that PROK2 acts on hematopoietic cells — promoting monocyte migration via pertussis toxin-sensitive G proteins and increasing leukocyte counts — expanded its role to immune cell regulation, while hypothalamic expression with circadian variation linked it to feeding/drinking behavior.\",\n      \"evidence\": \"Adenoviral in vivo delivery with CBC counts and colony-forming assays; ICV/microinjection feeding assays; in situ hybridization in SCN\",\n      \"pmids\": [\"15548611\", \"15066905\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Whether circadian PROK2 rhythm directly drives behavioral outputs vs. acting as an output signal unclear\", \"Brain circuit identity for appetite regulation not resolved\"]\n    },\n    {\n      \"year\": 2005,\n      \"claim\": \"Structure–function analysis showing the N-terminal AVITGA motif is essential for receptor activation, and that its deletion creates a receptor antagonist, provided the first pharmacological tools and structural insight into PROK2–receptor interaction.\",\n      \"evidence\": \"Receptor binding, calcium transients in PKR1/PKR2-expressing CHO cells, MAPK assays, in vivo hyperalgesia with truncated peptides\",\n      \"pmids\": [\"16113687\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Atomic-level structure of PROK2–receptor complex unknown\", \"Mechanism of antagonism (competitive vs. allosteric) unresolved\"]\n    },\n    {\n      \"year\": 2006,\n      \"claim\": \"Mechanistic dissection of PROK2 nociception revealed PKCε translocation as the pathway sensitizing TRPV1, while PROK2 was shown to drive macrophage chemotaxis via PKR1-Gq signaling — not Gi — shifting understanding of receptor coupling in immune cells.\",\n      \"evidence\": \"PKCε translocation assay + PKC antagonists in DRG neurons; macrophage chemotaxis with U73122 and pertussis toxin; PKR1 knockout mice\",\n      \"pmids\": [\"16687502\", \"16299550\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Whether PKCε pathway operates in all nociceptor subtypes unclear\", \"Gq-specific signaling intermediates in macrophages not mapped\"]\n    },\n    {\n      \"year\": 2007,\n      \"claim\": \"The demonstration that G-CSF drives PROK2 expression in tumor-infiltrating CD11b+Gr1+ myeloid cells and that anti-Bv8 antibodies suppress myeloid mobilization and tumor angiogenesis established PROK2 as a key mediator linking innate immunity to tumor vasculature.\",\n      \"evidence\": \"Anti-Bv8 antibody treatment in tumor-bearing mice, flow cytometry of myeloid cells, vascular density analysis; confirmed in RIP-Tag transgenic model\",\n      \"pmids\": [\"18064003\", \"18268320\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Direct versus indirect effects on endothelial cells in tumors not fully dissected\", \"Whether anti-Bv8 is effective in established (late-stage) tumors remains uncertain\"]\n    },\n    {\n      \"year\": 2009,\n      \"claim\": \"Genetic knockout of PKR1 and PKR2 proved that granulocyte-derived PROK2 is the primary initiator of inflammatory pain; a PKR1-dependent feedback loop regulating PROK2 levels was uncovered, and a small-molecule PKR antagonist achieved analgesia.\",\n      \"evidence\": \"CFA inflammation model in PKR1/PKR2 KO mice, PROK2 purification from granulocytes, non-peptide antagonist treatment\",\n      \"pmids\": [\"19667192\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Molecular identity of non-peptide antagonist target specificity not fully characterized\", \"Contribution of neuronal vs. immune cell PROK2 not resolved\"]\n    },\n    {\n      \"year\": 2010,\n      \"claim\": \"Determination of the 3D NMR structure of Bv8 revealed a colipase/mamba-toxin fold and showed that N-terminal residues critical for receptor activation are flexible and do not alter the core structure, suggesting an allosteric binding mechanism.\",\n      \"evidence\": \"Chemical synthesis, NMR spectroscopy, functional validation in neuroblastoma cells and DRG neurons\",\n      \"pmids\": [\"20677202\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"No receptor-bound co-structure available\", \"How N-terminal flexibility translates to receptor activation mechanistically unknown\"]\n    },\n    {\n      \"year\": 2012,\n      \"claim\": \"G-CSF-induced PROK2 expression was shown to require STAT3 binding directly to the Bv8 promoter, completing the transcriptional mechanism linking tumor-derived G-CSF to myeloid PROK2 upregulation; concurrently, receptor-selective Bv8 analogs demonstrated differential PKR1/PKR2 contributions to pain modulation.\",\n      \"evidence\": \"ChIP for pSTAT3 at Bv8 promoter, luciferase reporter, siRNA knockdown; W24A Bv8 binding/calcium assays and in vivo hyperalgesia with β-endorphin measurement\",\n      \"pmids\": [\"22528488\", \"22122547\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Whether STAT3 is sufficient or requires co-factors for Bv8 transcription unknown\", \"Central opioid activation via PKR2 pathway not fully mapped\"]\n    },\n    {\n      \"year\": 2013,\n      \"claim\": \"Discovery of a BV8–JAK2–STAT3 feed-forward loop in myeloid leukemia cells, where PROK2 both activates and is transcriptionally induced by STAT3, provided a mechanistic basis for autocrine amplification in tumor-associated myeloid cells; simultaneously, loss-of-function mutations in PROK2/PROKR2 were definitively linked to Kallmann syndrome through defective GnRH neuron migration.\",\n      \"evidence\": \"JAK2 inhibition + BV8 shRNA in leukemia xenografts; Prok2/Prokr2 KO mouse phenotyping with olfactory bulb and GnRH analyses; patient mutation functional characterization\",\n      \"pmids\": [\"23548897\", \"23596439\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Whether the feed-forward loop operates in non-myeloid tumors unclear\", \"Molecular mechanism of GnRH neuron guidance by PROK2 gradient not resolved\"]\n    },\n    {\n      \"year\": 2019,\n      \"claim\": \"Quantitative analysis in Prok2 and Prokr2 mutant mice revealed that ~75% of GABAergic olfactory bulb interneurons require PROK2/PROKR2 for tangential and radial migration from the SVZ-RMS, establishing PROK2 as a dominant guidance cue for postnatal interneuron migration.\",\n      \"evidence\": \"Prok2-EGFP and Prokr2-LacZ knockin reporters, genetic KO phenotyping with immunofluorescence and cell counting\",\n      \"pmids\": [\"31132148\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Downstream cytoskeletal effectors in migrating neuroblasts unknown\", \"Whether PROK2 acts as chemoattractant versus motogen in this context unresolved\"]\n    },\n    {\n      \"year\": 2020,\n      \"claim\": \"PROK2 was shown to activate AKT/GSK3β signaling for cardiomyocyte protection and to promote cervical cancer cell invasion via MMP15 upregulation, extending its functional repertoire to cardiac and oncological contexts.\",\n      \"evidence\": \"AKT KO cardiomyocytes + PKRA7 antagonist in diabetic mice; PROK2 siRNA/overexpression in HeLa cells with transwell invasion assays\",\n      \"pmids\": [\"32508669\", \"32887509\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Transcriptional mechanism linking PROK2 to MMP15 not identified\", \"Whether cardiomyocyte effects are receptor subtype-specific not resolved\", \"Single-lab findings for each\"]\n    },\n    {\n      \"year\": 2022,\n      \"claim\": \"Circuit-level dissection showed that PROK2's anorexigenic action is mediated specifically by PKR2 neurons in the amygdala — not hypothalamus — with MRAP2 acting as a modulator of receptor signaling, resolving the anatomical locus of PROK2 appetite suppression.\",\n      \"evidence\": \"Targeted PKR2 silencing and DREADD chemogenetic manipulation of amygdala neurons; MRAP2 overexpression/knockdown with behavioral food intake assays\",\n      \"pmids\": [\"36539034\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Downstream amygdala circuits mediating anorexia not mapped\", \"Whether MRAP2 modulation is specific to amygdala PKR2 neurons unclear\"]\n    },\n    {\n      \"year\": 2024,\n      \"claim\": \"Central PROK2 infusion was shown to activate the hypothalamic-pituitary-gonadal axis by increasing GnRH mRNA and elevating FSH, LH, and testosterone, providing direct evidence that PROK2 is an upstream regulator of reproductive hormone release.\",\n      \"evidence\": \"ICV osmotic mini-pump infusion with RT-PCR for GnRH and ELISA for gonadotropins/testosterone\",\n      \"pmids\": [\"38740671\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Whether the effect is mediated by direct action on GnRH neurons vs. intermediate neurons unknown\", \"Receptor subtype mediating HPG activation not identified\", \"Single-lab study\"]\n    },\n    {\n      \"year\": null,\n      \"claim\": \"Key unresolved questions include the atomic structure of PROK2 bound to PKR1 or PKR2, the molecular basis for receptor subtype selectivity in different tissues, and the intracellular signaling cascades linking PROK2 to cytoskeletal rearrangements during neuronal migration.\",\n      \"evidence\": \"\",\n      \"pmids\": [],\n      \"confidence\": \"Low\",\n      \"gaps\": [\"No co-crystal or cryo-EM structure of PROK2–receptor complex\", \"Receptor subtype-specific signaling pathways in neuronal migration undefined\", \"In vivo redundancy between PKR1 and PKR2 in most physiological contexts not systematically addressed\"]\n    }\n  ],\n  \"mechanism_profile\": {\n    \"molecular_activity\": [\n      {\"term_id\": \"GO:0048018\", \"supporting_discovery_ids\": [3, 7, 8, 9, 15]}\n    ],\n    \"localization\": [\n      {\"term_id\": \"GO:0005576\", \"supporting_discovery_ids\": [0, 4, 5, 10, 14]}\n    ],\n    \"pathway\": [\n      {\"term_id\": \"R-HSA-162582\", \"supporting_discovery_ids\": [2, 3, 8, 18, 25]},\n      {\"term_id\": \"R-HSA-168256\", \"supporting_discovery_ids\": [5, 9, 10, 13, 14]},\n      {\"term_id\": \"R-HSA-112316\", \"supporting_discovery_ids\": [2, 6, 11, 19, 21]},\n      {\"term_id\": \"R-HSA-1266738\", \"supporting_discovery_ids\": [19, 21, 26]}\n    ],\n    \"complexes\": [],\n    \"partners\": [\n      \"PROKR1\",\n      \"PROKR2\",\n      \"TRPV1\",\n      \"STAT3\",\n      \"CSF3\",\n      \"MRAP2\",\n      \"JAK2\",\n      \"MMP15\"\n    ],\n    \"other_free_text\": []\n  }\n}\n```"}