{"gene":"PROK1","run_date":"2026-06-10T06:43:35","timeline":{"discoveries":[{"year":2002,"finding":"EG-VEGF/prokineticin 1 (PROK1) and prokineticin 2 are cognate ligands of two orphan G-protein-coupled receptors, ZAQ (PK-R1/PROKR1) and I5E (PK-R2/PROKR2). Binding induces a transient increase in intracellular calcium concentration with nanomolar potency in CHO cells expressing either receptor, and provokes rapid phosphorylation of p44/42 MAP kinase and DNA synthesis in bovine adrenal capillary endothelial cells.","method":"Radioligand binding assays, intracellular calcium measurements in CHO cells expressing PROKR1/PROKR2, MAP kinase phosphorylation assays, DNA synthesis assay in endothelial cells","journal":"Biochemical and biophysical research communications","confidence":"High","confidence_rationale":"Tier 1-2 / Strong — multiple orthogonal functional assays (calcium signaling, MAP kinase, DNA synthesis) with defined receptor-ligand pairs, replicated across labs","pmids":["12054613"],"is_preprint":false},{"year":2005,"finding":"PROK1/PK1 induces differentiation of murine and human bone marrow cells into the monocyte/macrophage lineage and modulates human peripheral blood monocyte function, causing morphological changes, down-regulation of B7-1, CD14, CCR5, and CXCR4, and elevated IL-12 and TNFα with reduced IL-10 production in response to LPS.","method":"In vitro bone marrow differentiation assay, flow cytometry, cytokine measurement (ELISA), morphological analysis; macrophage identified as in vivo cellular target by tissue section binding","journal":"Journal of leukocyte biology","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — multiple functional readouts in a single lab; receptor identity on macrophages not fully delineated by mutagenesis","pmids":["15908459"],"is_preprint":false},{"year":2009,"finding":"EG-VEGF inhibits extravillous trophoblast (EVT) migration, invasion, and tube-like organisation via its receptors PKR1 and PKR2. The inhibitory effect on invasion was supported by decreased MMP-2 and MMP-9 production. siRNA-mediated knockdown of PKR2 (but not PKR1) reversed EG-VEGF-induced inhibitory effects on trophoblast invasion.","method":"Human villous explants and HTR-8/SVneo cell line; migration/invasion assays; gelatin zymography for MMP-2/MMP-9; siRNA knockdown of PROKR2","journal":"Journal of cellular and molecular medicine","confidence":"High","confidence_rationale":"Tier 2 / Strong — receptor-specific siRNA knockdown plus functional invasion assays and protease activity measurements; replicated in multiple trophoblast models","pmids":["19602057"],"is_preprint":false},{"year":2010,"finding":"EG-VEGF (PROK1) stimulates proliferation, migration, and survival of placental microvascular endothelial cells (HPEC) and is more potent than VEGF in promoting sprouting and pseudovascular organisation. PROKR1 mediates EG-VEGF angiogenic effects (proliferation, migration, survival, sprouting), whereas PROKR2 mediates cellular permeability and paracellular transport.","method":"Primary placental microvascular endothelial cells and HUVEC; proliferation, migration, survival, spheroid sprouting, permeability assays; siRNA knockdown and neutralising antibodies targeting PROKR1 vs PROKR2","journal":"Molecular biology of the cell","confidence":"High","confidence_rationale":"Tier 2 / Strong — receptor-specific siRNA and antibody strategies with multiple orthogonal functional readouts distinguishing PROKR1 vs PROKR2 functions","pmids":["20587779"],"is_preprint":false},{"year":2011,"finding":"hCG increases EG-VEGF, PROKR1, and PROKR2 mRNA and protein expression in placental explants and primary trophoblasts in a dose- and time-dependent manner via cAMP response elements in the EG-VEGF promoter. The hCG effects are transcriptional and post-transcriptional and mediated via cAMP.","method":"Placental explants and primary trophoblast cultures; qPCR; Western blot; promoter-reporter assay; cAMP measurement; pharmacological inhibition of cAMP pathway","journal":"Cellular and molecular life sciences : CMLS","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — promoter-reporter and mRNA/protein analyses in primary tissue, single lab, no mutagenesis of specific CRE sites","pmids":["22138749"],"is_preprint":false},{"year":2012,"finding":"EG-VEGF increases trophoblast proliferation via the homeobox gene HLX, and this proliferative effect is mediated specifically through PROKR1 but not PROKR2. EG-VEGF also increases vascularization of placental villi and promotes their survival.","method":"Placental explants and primary trophoblast cultures; [³H]-thymidine incorporation; Ki67 staining; PROKR1/PROKR2-specific siRNA; HLX expression measurement","journal":"Cellular and molecular life sciences : CMLS","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — receptor-specific siRNA with downstream gene (HLX) identification, single lab","pmids":["22941044"],"is_preprint":false},{"year":2009,"finding":"PROK1 signals via PROKR1 to induce IL-11 expression through a Gq/11, ERK, Ca²⁺, calcineurin, and NFAT (calcineurin/NFAT) dependent pathway. RCAN1-4 (regulator of calcineurin 1 isoform 4) acts as a negative regulator of this pathway. Knockdown of endogenous PROK1 using lentiviral miRNA significantly reduced IL-11 expression and secretion in first-trimester decidua.","method":"PROKR1-Ishikawa cells; qPCR; ELISA; pharmacological inhibition of Gq, ERK, Ca²⁺, calcineurin/NFAT; adenoviral overexpression of RCAN1-4; lentiviral miRNA knockdown of PROK1 in decidua","journal":"Molecular human reproduction","confidence":"High","confidence_rationale":"Tier 2 / Strong — multiple orthogonal pharmacological inhibitors defining pathway components, combined with gain- and loss-of-function experiments in primary tissue","pmids":["19801577"],"is_preprint":false},{"year":2010,"finding":"PROK1 regulates CTGF (connective tissue growth factor) expression in first-trimester decidua via the Gq, phospholipase C, cSrc, EGFR, MAPK/ERK kinase signalling pathway. CTGF in turn increases trophoblast adhesion to collagen IV and promotes tube-like structure formation.","method":"PROKR1-Ishikawa cells and first-trimester decidua; qPCR; Western blot; specific pathway inhibitors (Gq, PLC, cSrc, EGFR, MEK); miRNA constructs to knock down endogenous PROK1; HTR-8/SVneo adhesion and matrigel assays","journal":"Human reproduction (Oxford, England)","confidence":"High","confidence_rationale":"Tier 2 / Strong — multiple orthogonal pathway inhibitors plus miRNA knockdown in primary tissue, with downstream functional validation","pmids":["21098624"],"is_preprint":false},{"year":2016,"finding":"EG-VEGF activates ERK1/2 signalling, leading to upregulation of MMP2 and MMP9, thereby facilitating trophoblast cell invasion. PROKR1 localizes to primary cilia, and depletion of IFT88 (blocking ciliogenesis) inhibits EG-VEGF-induced ERK1/2 activation, MMP upregulation, and trophoblast invasion.","method":"HTR-8/SVneo cells; ERK1/2 inhibition; IFT88 siRNA knockdown; immunofluorescence localization of PROKR1 to primary cilia; invasion assays; Western blot for MMP2/MMP9","journal":"Journal of cellular physiology","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — subcellular localization (PROKR1 to primary cilia) functionally validated by IFT88 knockdown with defined signalling phenotype, single lab","pmids":["27736039"],"is_preprint":false},{"year":2007,"finding":"EG-VEGF (PROK1) and its receptors PKR1 and PKR2 are expressed in mouse placenta throughout gestation. EG-VEGF is mainly localised in the labyrinth layer (highest before E10.5 dpc), while PKR1 protein co-localises with EG-VEGF in the labyrinth and PKR2 is maintained over E10.5 dpc with both trophoblastic and endothelial cell localisations, indicating differential receptor engagement in distinct cell types.","method":"Mouse placental tissue; immunohistochemistry; qRT-PCR; Western blot at multiple gestational timepoints","journal":"Placenta","confidence":"Medium","confidence_rationale":"Tier 3 / Moderate — direct localization experiment with temporal specificity across gestation, but no functional intervention; replicated across multiple gestational ages","pmids":["17531315"],"is_preprint":false},{"year":2015,"finding":"PPARγ activation (rosiglitazone) increases EG-VEGF secretion and upregulates EG-VEGF, PROKR1, and PROKR2 expression in human trophoblasts and placental explants. PPARγ(-/-) mouse placentas have significantly decreased EG-VEGF levels. EG-VEGF mediates PPARγ effects on placental vascularization (via PROKR1 and PROKR2) and inhibition of trophoblast migration and invasion (via PROKR2).","method":"Human primary cytotrophoblasts; HTR-8/SVneo cells; placental explants; PPARγ(+/-) and PPARγ(-/-) mouse placentas; PROKR1/PROKR2 receptor antagonists; proliferation, migration, invasion, vascularization assays","journal":"American journal of physiology. Endocrinology and metabolism","confidence":"High","confidence_rationale":"Tier 2 / Strong — in vitro, ex vivo, and in vivo (knockout mouse) combined with receptor antagonists to map pathway; multiple orthogonal methods","pmids":["26081281"],"is_preprint":false},{"year":2017,"finding":"EG-VEGF increases JEG3 choriocarcinoma cell proliferation, migration, and invasion in 2D and 3D culture systems. Treatment with EG-VEGF receptor antagonists (targeting PROKR1/PROKR2) significantly reduced tumor development and progression in a novel in vivo choriocarcinoma mouse model (JEG3-luciferase injected into gravid SCID-mouse placenta).","method":"JEG3 cell line; 2D/3D culture proliferation, migration, invasion assays; PROKR1/PROKR2 antagonist treatment; in vivo placental injection CC mouse model; antibody-array and immunohistochemistry","journal":"Clinical cancer research","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — in vitro and in vivo receptor antagonism with mechanistic follow-up; single lab but multiple complementary approaches","pmids":["28899975"],"is_preprint":false},{"year":2005,"finding":"EG-VEGF/PK-1 elevates [³H]-thymidine incorporation, activates MAPK, and induces c-jun/fos mRNA expression in luteal endothelial cells (LEC), demonstrating direct mitogenic activity. EG-VEGF/PK-1 also inhibits serum starvation-induced apoptosis in LEC. In bovine luteal steroidogenic cells (which express only PK-R1), EG-VEGF/PK-1 elevated VEGF mRNA expression.","method":"Primary luteal endothelial cells; [³H]-thymidine incorporation; MAPK activation assay; RT-PCR for c-jun/fos; apoptosis assay under serum withdrawal; receptor expression characterization","journal":"Annals of anatomy","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — multiple functional readouts in primary cells; receptor subtype attribution based on expression profiling rather than knockdown/blockade","pmids":["16320832"],"is_preprint":false},{"year":2018,"finding":"Knockdown of EG-VEGF (PROK1) in pancreatic carcinoma cells (PANC-1 and BxPC-3) inhibited cell proliferation, induced G0/G1 cell cycle arrest, and promoted apoptosis. EG-VEGF silencing significantly reduced phosphorylated PI3K, AKT, and mTOR levels, placing EG-VEGF upstream of the PI3K/AKT/mTOR signalling pathway in pancreatic cancer cells.","method":"shRNA lentiviral knockdown of PROK1; MTT proliferation assay; flow cytometry (cell cycle and apoptosis); Western blot for p-PI3K, p-AKT, p-mTOR","journal":"Biomedicine & pharmacotherapy","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — shRNA loss-of-function with defined pathway readout; single lab, no rescue experiment or receptor identification","pmids":["30551529"],"is_preprint":false},{"year":2014,"finding":"EG-VEGF decreases metalloproteinase-2 and -9 activities and increases PGDH (prostaglandin-metabolising enzyme) expression in chorion trophoblast and fetal membrane explants. EG-VEGF and its receptors (PROKR1 and PROKR2) show increased expression in fetal membranes toward term with an abrupt decrease at the onset of labor.","method":"Human fetal membrane explants; primary chorion trophoblast cultures; MMP-2/MMP-9 activity assays; PGDH expression measurement; qRT-PCR and protein quantification across gestational timepoints","journal":"Biology of reproduction","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — direct functional assays in primary human tissue with defined enzyme activity readouts; single lab","pmids":["25122063"],"is_preprint":false}],"current_model":"PROK1 (EG-VEGF/PK1) is a secreted cysteine-rich peptide that signals through two G-protein-coupled receptors, PROKR1 and PROKR2, to activate intracellular calcium, MAP kinase/ERK, PI3K/AKT/mTOR, and calcineurin/NFAT pathways; PROKR1 primarily mediates angiogenic and proliferative effects (endothelial cell mitogenesis, trophoblast proliferation via HLX, CTGF induction via Gq-PLC-cSrc-EGFR-ERK), while PROKR2 mediates endothelial permeability and inhibition of trophoblast invasion (via MMP-2/MMP-9 suppression), with PROKR1 localising to primary cilia to transduce ERK-dependent invasion signals; upstream regulators include hCG (via cAMP/CRE) and PPARγ, and the protein additionally drives monocyte differentiation and acts upstream of the PI3K/AKT/mTOR axis in cancer cells."},"narrative":{"mechanistic_narrative":"PROK1 (EG-VEGF/prokineticin 1) is a secreted peptide that acts as an angiogenic and cell-fate regulator by binding the two G-protein-coupled receptors PROKR1 and PROKR2, triggering nanomolar transient intracellular calcium flux, p44/42 MAP kinase phosphorylation, and DNA synthesis [PMID:12054613]. The two receptors partition its activities: PROKR1 transduces angiogenic and proliferative outputs—endothelial proliferation, migration, survival and sprouting [PMID:20587779], and trophoblast proliferation through the homeobox gene HLX [PMID:22941044]—whereas PROKR2 mediates endothelial permeability and paracellular transport [PMID:20587779] and the suppression of trophoblast migration and invasion via reduced MMP-2/MMP-9 production [PMID:19602057]. In the placental decidua, PROK1 signals through PROKR1 to induce IL-11 via a Gq/11–ERK–calcium–calcineurin/NFAT cascade negatively regulated by RCAN1-4 [PMID:19801577], and to induce CTGF through a Gq–PLC–cSrc–EGFR–MEK/ERK pathway that promotes trophoblast adhesion and tube formation [PMID:21098624]; PROKR1 localizes to primary cilia, where ciliogenesis (IFT88-dependent) is required for EG-VEGF–driven ERK activation, MMP induction, and trophoblast invasion [PMID:27736039]. PROK1 expression and its receptors are induced upstream by hCG via cAMP/CRE elements in the EG-VEGF promoter [PMID:22138749] and by PPARγ activation [PMID:26081281]. Beyond reproduction, PROK1 directs bone marrow cells toward the monocyte/macrophage lineage and reprograms monocyte cytokine output [PMID:15908459], and acts upstream of the PI3K/AKT/mTOR axis to sustain proliferation and survival in pancreatic carcinoma cells [PMID:30551529], with receptor antagonism limiting choriocarcinoma growth in vivo [PMID:28899975].","teleology":[{"year":2002,"claim":"Establishing that PROK1 is a functional ligand for two specific GPCRs answered how this secreted peptide initiates signaling and links it to endothelial mitogenesis.","evidence":"Radioligand binding, calcium imaging in CHO cells expressing PROKR1/PROKR2, MAP kinase and DNA synthesis assays in endothelial cells","pmids":["12054613"],"confidence":"High","gaps":["Did not separate which receptor drives which downstream output","No structural basis for ligand-receptor recognition"]},{"year":2005,"claim":"Demonstrating PROK1-driven monocyte/macrophage differentiation and cytokine reprogramming extended its role beyond angiogenesis into immune cell fate.","evidence":"In vitro bone marrow differentiation, flow cytometry, cytokine ELISA, tissue binding","pmids":["15908459"],"confidence":"Medium","gaps":["Receptor mediating the myeloid effect not defined by mutagenesis","In vivo relevance not established"]},{"year":2005,"claim":"Showing direct mitogenic and anti-apoptotic activity on luteal endothelial cells and VEGF induction in steroidogenic cells linked PROK1 to ovarian vascular biology.","evidence":"Primary luteal endothelial cells; thymidine incorporation, MAPK assay, c-jun/fos RT-PCR, apoptosis under serum withdrawal","pmids":["16320832"],"confidence":"Medium","gaps":["Receptor attribution based on expression profiling not knockdown","No in vivo confirmation"]},{"year":2009,"claim":"Dissecting the IL-11 induction pathway defined the PROKR1 intracellular cascade (Gq/11-ERK-Ca2+-calcineurin/NFAT) and its negative regulator RCAN1-4 in decidua.","evidence":"PROKR1-Ishikawa cells; pharmacological pathway inhibitors, RCAN1-4 overexpression, lentiviral miRNA knockdown in primary decidua","pmids":["19801577"],"confidence":"High","gaps":["Physiological role of decidual IL-11 induction not established in vivo"]},{"year":2009,"claim":"Receptor-specific knockdown established that PROKR2 mediates PROK1 inhibition of trophoblast invasion through MMP-2/MMP-9 suppression.","evidence":"Villous explants and HTR-8/SVneo cells; invasion assays, gelatin zymography, PROKR2 siRNA","pmids":["19602057"],"confidence":"High","gaps":["Mechanism linking PROKR2 to MMP transcription not resolved"]},{"year":2010,"claim":"Receptor-selective siRNA and antibodies partitioned PROK1 angiogenic functions to PROKR1 and permeability functions to PROKR2 in placental endothelium.","evidence":"Primary placental microvascular endothelial cells; proliferation/migration/survival/sprouting/permeability assays with PROKR1 vs PROKR2 knockdown and neutralizing antibodies","pmids":["20587779"],"confidence":"High","gaps":["Divergent G-protein coupling underlying the receptor split not defined"]},{"year":2010,"claim":"Mapping CTGF induction through Gq-PLC-cSrc-EGFR-ERK defined how PROKR1 promotes trophoblast adhesion and tube formation.","evidence":"PROKR1-Ishikawa cells and decidua; pathway inhibitors, miRNA knockdown, adhesion and matrigel assays","pmids":["21098624"],"confidence":"High","gaps":["Direct EGFR transactivation mechanism not biochemically resolved"]},{"year":2011,"claim":"Identifying hCG as an upstream inducer via cAMP/CRE elements placed PROK1 within hormonal control of placentation.","evidence":"Placental explants and trophoblasts; qPCR, Western, promoter-reporter, cAMP measurement, pathway inhibition","pmids":["22138749"],"confidence":"Medium","gaps":["Specific CRE sites not validated by mutagenesis"]},{"year":2012,"claim":"Linking PROK1-driven trophoblast proliferation to HLX through PROKR1 identified a downstream transcriptional effector of the proliferative branch.","evidence":"Placental explants; thymidine incorporation, Ki67, receptor-specific siRNA, HLX measurement","pmids":["22941044"],"confidence":"Medium","gaps":["How PROKR1 signaling regulates HLX transcriptionally not defined"]},{"year":2014,"claim":"Showing PROK1 decreases MMP-2/9 activity and raises PGDH in fetal membranes with gestational dynamics connected it to fetal membrane remodeling and labor onset.","evidence":"Human fetal membrane and chorion trophoblast explants; MMP activity assays, PGDH and receptor expression across gestation","pmids":["25122063"],"confidence":"Medium","gaps":["Causal role in labor timing not tested","Receptor specificity not dissected"]},{"year":2015,"claim":"Integrating PPARγ as an upstream activator using knockout mice and antagonists positioned PROK1 as a downstream effector of PPARγ in placental vascularization and invasion control.","evidence":"Human trophoblasts and explants, PPARγ-null mouse placentas, PROKR1/PROKR2 antagonists across proliferation/migration/invasion/vascularization assays","pmids":["26081281"],"confidence":"High","gaps":["Direct PPARγ binding to the EG-VEGF locus not shown"]},{"year":2016,"claim":"Localizing PROKR1 to primary cilia and showing IFT88-dependence of ERK/MMP activation revealed a ciliary requirement for the invasion-promoting branch.","evidence":"HTR-8/SVneo cells; immunofluorescence, IFT88 siRNA, ERK inhibition, invasion assays, MMP Western blots","pmids":["27736039"],"confidence":"Medium","gaps":["How ciliary localization couples PROKR1 to ERK not defined","Single lab"]},{"year":2017,"claim":"Demonstrating receptor antagonism reduces choriocarcinoma growth in an in vivo model established PROK1 signaling as a therapeutic target in trophoblastic tumors.","evidence":"JEG3 cells; 2D/3D proliferation/migration/invasion, PROKR1/PROKR2 antagonists, in vivo placental injection model","pmids":["28899975"],"confidence":"Medium","gaps":["Relative contributions of PROKR1 vs PROKR2 to tumor effect not separated"]},{"year":2018,"claim":"Placing PROK1 upstream of PI3K/AKT/mTOR in pancreatic carcinoma extended its proliferative/survival signaling role to a non-reproductive cancer.","evidence":"shRNA knockdown in PANC-1/BxPC-3; proliferation, cell cycle, apoptosis assays, phospho-PI3K/AKT/mTOR Western blots","pmids":["30551529"],"confidence":"Medium","gaps":["No rescue experiment","Receptor mediating the effect not identified"]},{"year":null,"claim":"The molecular basis for divergent PROKR1 vs PROKR2 G-protein coupling and the structural determinants of ligand-receptor selectivity remain unresolved.","evidence":"","pmids":[],"confidence":"Medium","gaps":["No structural model of PROK1 bound to either receptor","Mechanism dictating receptor-specific downstream outputs unknown"]}],"mechanism_profile":{"molecular_activity":[{"term_id":"GO:0048018","term_label":"receptor ligand activity","supporting_discovery_ids":[0,3]},{"term_id":"GO:0060089","term_label":"molecular transducer activity","supporting_discovery_ids":[0]}],"localization":[{"term_id":"GO:0005576","term_label":"extracellular region","supporting_discovery_ids":[0,3]},{"term_id":"GO:0005929","term_label":"cilium","supporting_discovery_ids":[8]}],"pathway":[{"term_id":"R-HSA-162582","term_label":"Signal Transduction","supporting_discovery_ids":[0,6,7]},{"term_id":"R-HSA-1266738","term_label":"Developmental Biology","supporting_discovery_ids":[3,9,10]},{"term_id":"R-HSA-1474165","term_label":"Reproduction","supporting_discovery_ids":[2,4,5]},{"term_id":"R-HSA-168256","term_label":"Immune System","supporting_discovery_ids":[1]}],"complexes":[],"partners":["PROKR1","PROKR2"],"other_free_text":[]}},"prefetch_data":{"uniprot":{"accession":"P58294","full_name":"Prokineticin-1","aliases":["Endocrine-gland-derived vascular endothelial growth factor","EG-VEGF","Mambakine"],"length_aa":105,"mass_kda":11.7,"function":"Potently contracts gastrointestinal (GI) smooth muscle. Induces proliferation, migration and fenestration (the formation of membrane discontinuities) in capillary endothelial cells derived from endocrine glands. Has little or no effect on a variety of other endothelial and non-endothelial cell types. Induces proliferation and differentiation, but not migration, of enteric neural crest cells. Directly influences neuroblastoma progression by promoting the proliferation and migration of neuroblastoma cells. Positively regulates PTGS2 expression and prostaglandin synthesis. May play a role in placentation. May play a role in normal and pathological testis angiogenesis","subcellular_location":"Secreted","url":"https://www.uniprot.org/uniprotkb/P58294/entry"},"depmap":{"release":"DepMap","has_data":true,"is_common_essential":false,"resolved_as":"","url":"https://depmap.org/portal/gene/PROK1","classification":"Not Classified","n_dependent_lines":1,"n_total_lines":1208,"dependency_fraction":0.0008278145695364238},"opencell":{"profiled":false,"resolved_as":"","ensg_id":"","cell_line_id":"","localizations":[],"interactors":[],"url":"https://opencell.sf.czbiohub.org/search/PROK1","total_profiled":1310},"omim":[{"mim_id":"607123","title":"PROKINETICIN RECEPTOR 2; PROKR2","url":"https://www.omim.org/entry/607123"},{"mim_id":"607122","title":"PROKINETICIN RECEPTOR 1; PROKR1","url":"https://www.omim.org/entry/607122"},{"mim_id":"607002","title":"PROKINETICIN 2; PROK2","url":"https://www.omim.org/entry/607002"},{"mim_id":"606233","title":"PROKINETICIN 1; PROK1","url":"https://www.omim.org/entry/606233"}],"hpa":{"profiled":true,"resolved_as":"","reliability":"","locations":[],"tissue_specificity":"Tissue enhanced","tissue_distribution":"Detected in many","driving_tissues":[{"tissue":"ovary","ntpm":190.8},{"tissue":"placenta","ntpm":47.2},{"tissue":"testis","ntpm":56.2}],"url":"https://www.proteinatlas.org/search/PROK1"},"hgnc":{"alias_symbol":["PK1","PRK1","EGVEGF","EG-VEGF"],"prev_symbol":[]},"alphafold":{"accession":"P58294","domains":[{"cath_id":"2.10.80.10","chopping":"21-105","consensus_level":"medium","plddt":89.4501,"start":21,"end":105}],"viewer_url":"https://alphafold.ebi.ac.uk/entry/P58294","model_url":"https://alphafold.ebi.ac.uk/files/AF-P58294-F1-model_v6.cif","pae_url":"https://alphafold.ebi.ac.uk/files/AF-P58294-F1-predicted_aligned_error_v6.png","plddt_mean":90.0},"mouse_models":{"mgi_url":"https://www.informatics.jax.org/marker/summary?nomen=PROK1","jax_strain_url":"https://www.jax.org/strain/search?query=PROK1"},"sequence":{"accession":"P58294","fasta_url":"https://rest.uniprot.org/uniprotkb/P58294.fasta","uniprot_url":"https://www.uniprot.org/uniprotkb/P58294/entry","alphafold_viewer_url":"https://alphafold.ebi.ac.uk/entry/P58294"}},"corpus_meta":[{"pmid":"12054613","id":"PMC_12054613","title":"Isolation 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reproduction","url":"https://pubmed.ncbi.nlm.nih.gov/25122063","citation_count":15,"is_preprint":false},{"pmid":"1662319","id":"PMC_1662319","title":"Receptor-mediated increase in cytosolic calcium in LLC-PK1 cells by platelet activating factor and thromboxane A2.","date":"1991","source":"Kidney international","url":"https://pubmed.ncbi.nlm.nih.gov/1662319","citation_count":15,"is_preprint":false}],"cost":{"stage1":{"model":"claude-sonnet-4-6","input_tokens":54330,"output_tokens":4662,"usd":0.11646,"stage1_stop_reason":"end_turn"},"stage2":{"model":"claude-opus-4-8","input_tokens":12373,"output_tokens":4140,"usd":0.082683,"stage2_stop_reason":"end_turn"},"total_usd":0.199143,"stage1_batch_id":"msgbatch_01CNoDbkChHEkgrJnL7BwtGJ","stage2_batch_id":"msgbatch_016Y4x9E9Wg5VQDANj9quSQD","note":"batch pricing = 50% of standard"},"stage1_raw":"Looking through the abstracts, I need to identify papers about the canonical PROK1/EG-VEGF/PK1 protein (the human prokineticin 1 gene). Many papers in this corpus are about LLC-PK1 cells (a porcine kidney cell line) which is NOT the same as PROK1 the gene. I need to carefully distinguish between:\n- Papers about EG-VEGF/PROK1/PK1 protein (the gene of interest)\n- Papers about LLC-PK1 cells (a cell line, irrelevant)\n- Paper [36] and [82] about unrelated \"PK1\" entities (polymer drug conjugate; baculovirus kinase)\n\nRelevant papers: [1], [9], [10], [11], [16], [17], [24], [25], [30], [35], [47], [51], [53], [54], [55], [61], [62], [78], [99]\n\n```json\n{\n  \"discoveries\": [\n    {\n      \"year\": 2002,\n      \"finding\": \"EG-VEGF/prokineticin 1 (PROK1) and prokineticin 2 are cognate ligands of two orphan G-protein-coupled receptors, ZAQ (PK-R1/PROKR1) and I5E (PK-R2/PROKR2). Binding induces a transient increase in intracellular calcium concentration with nanomolar potency in CHO cells expressing either receptor, and provokes rapid phosphorylation of p44/42 MAP kinase and DNA synthesis in bovine adrenal capillary endothelial cells.\",\n      \"method\": \"Radioligand binding assays, intracellular calcium measurements in CHO cells expressing PROKR1/PROKR2, MAP kinase phosphorylation assays, DNA synthesis assay in endothelial cells\",\n      \"journal\": \"Biochemical and biophysical research communications\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1-2 / Strong — multiple orthogonal functional assays (calcium signaling, MAP kinase, DNA synthesis) with defined receptor-ligand pairs, replicated across labs\",\n      \"pmids\": [\"12054613\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2005,\n      \"finding\": \"PROK1/PK1 induces differentiation of murine and human bone marrow cells into the monocyte/macrophage lineage and modulates human peripheral blood monocyte function, causing morphological changes, down-regulation of B7-1, CD14, CCR5, and CXCR4, and elevated IL-12 and TNFα with reduced IL-10 production in response to LPS.\",\n      \"method\": \"In vitro bone marrow differentiation assay, flow cytometry, cytokine measurement (ELISA), morphological analysis; macrophage identified as in vivo cellular target by tissue section binding\",\n      \"journal\": \"Journal of leukocyte biology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — multiple functional readouts in a single lab; receptor identity on macrophages not fully delineated by mutagenesis\",\n      \"pmids\": [\"15908459\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2009,\n      \"finding\": \"EG-VEGF inhibits extravillous trophoblast (EVT) migration, invasion, and tube-like organisation via its receptors PKR1 and PKR2. The inhibitory effect on invasion was supported by decreased MMP-2 and MMP-9 production. siRNA-mediated knockdown of PKR2 (but not PKR1) reversed EG-VEGF-induced inhibitory effects on trophoblast invasion.\",\n      \"method\": \"Human villous explants and HTR-8/SVneo cell line; migration/invasion assays; gelatin zymography for MMP-2/MMP-9; siRNA knockdown of PROKR2\",\n      \"journal\": \"Journal of cellular and molecular medicine\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — receptor-specific siRNA knockdown plus functional invasion assays and protease activity measurements; replicated in multiple trophoblast models\",\n      \"pmids\": [\"19602057\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2010,\n      \"finding\": \"EG-VEGF (PROK1) stimulates proliferation, migration, and survival of placental microvascular endothelial cells (HPEC) and is more potent than VEGF in promoting sprouting and pseudovascular organisation. PROKR1 mediates EG-VEGF angiogenic effects (proliferation, migration, survival, sprouting), whereas PROKR2 mediates cellular permeability and paracellular transport.\",\n      \"method\": \"Primary placental microvascular endothelial cells and HUVEC; proliferation, migration, survival, spheroid sprouting, permeability assays; siRNA knockdown and neutralising antibodies targeting PROKR1 vs PROKR2\",\n      \"journal\": \"Molecular biology of the cell\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — receptor-specific siRNA and antibody strategies with multiple orthogonal functional readouts distinguishing PROKR1 vs PROKR2 functions\",\n      \"pmids\": [\"20587779\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2011,\n      \"finding\": \"hCG increases EG-VEGF, PROKR1, and PROKR2 mRNA and protein expression in placental explants and primary trophoblasts in a dose- and time-dependent manner via cAMP response elements in the EG-VEGF promoter. The hCG effects are transcriptional and post-transcriptional and mediated via cAMP.\",\n      \"method\": \"Placental explants and primary trophoblast cultures; qPCR; Western blot; promoter-reporter assay; cAMP measurement; pharmacological inhibition of cAMP pathway\",\n      \"journal\": \"Cellular and molecular life sciences : CMLS\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — promoter-reporter and mRNA/protein analyses in primary tissue, single lab, no mutagenesis of specific CRE sites\",\n      \"pmids\": [\"22138749\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2012,\n      \"finding\": \"EG-VEGF increases trophoblast proliferation via the homeobox gene HLX, and this proliferative effect is mediated specifically through PROKR1 but not PROKR2. EG-VEGF also increases vascularization of placental villi and promotes their survival.\",\n      \"method\": \"Placental explants and primary trophoblast cultures; [³H]-thymidine incorporation; Ki67 staining; PROKR1/PROKR2-specific siRNA; HLX expression measurement\",\n      \"journal\": \"Cellular and molecular life sciences : CMLS\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — receptor-specific siRNA with downstream gene (HLX) identification, single lab\",\n      \"pmids\": [\"22941044\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2009,\n      \"finding\": \"PROK1 signals via PROKR1 to induce IL-11 expression through a Gq/11, ERK, Ca²⁺, calcineurin, and NFAT (calcineurin/NFAT) dependent pathway. RCAN1-4 (regulator of calcineurin 1 isoform 4) acts as a negative regulator of this pathway. Knockdown of endogenous PROK1 using lentiviral miRNA significantly reduced IL-11 expression and secretion in first-trimester decidua.\",\n      \"method\": \"PROKR1-Ishikawa cells; qPCR; ELISA; pharmacological inhibition of Gq, ERK, Ca²⁺, calcineurin/NFAT; adenoviral overexpression of RCAN1-4; lentiviral miRNA knockdown of PROK1 in decidua\",\n      \"journal\": \"Molecular human reproduction\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — multiple orthogonal pharmacological inhibitors defining pathway components, combined with gain- and loss-of-function experiments in primary tissue\",\n      \"pmids\": [\"19801577\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2010,\n      \"finding\": \"PROK1 regulates CTGF (connective tissue growth factor) expression in first-trimester decidua via the Gq, phospholipase C, cSrc, EGFR, MAPK/ERK kinase signalling pathway. CTGF in turn increases trophoblast adhesion to collagen IV and promotes tube-like structure formation.\",\n      \"method\": \"PROKR1-Ishikawa cells and first-trimester decidua; qPCR; Western blot; specific pathway inhibitors (Gq, PLC, cSrc, EGFR, MEK); miRNA constructs to knock down endogenous PROK1; HTR-8/SVneo adhesion and matrigel assays\",\n      \"journal\": \"Human reproduction (Oxford, England)\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — multiple orthogonal pathway inhibitors plus miRNA knockdown in primary tissue, with downstream functional validation\",\n      \"pmids\": [\"21098624\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2016,\n      \"finding\": \"EG-VEGF activates ERK1/2 signalling, leading to upregulation of MMP2 and MMP9, thereby facilitating trophoblast cell invasion. PROKR1 localizes to primary cilia, and depletion of IFT88 (blocking ciliogenesis) inhibits EG-VEGF-induced ERK1/2 activation, MMP upregulation, and trophoblast invasion.\",\n      \"method\": \"HTR-8/SVneo cells; ERK1/2 inhibition; IFT88 siRNA knockdown; immunofluorescence localization of PROKR1 to primary cilia; invasion assays; Western blot for MMP2/MMP9\",\n      \"journal\": \"Journal of cellular physiology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — subcellular localization (PROKR1 to primary cilia) functionally validated by IFT88 knockdown with defined signalling phenotype, single lab\",\n      \"pmids\": [\"27736039\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2007,\n      \"finding\": \"EG-VEGF (PROK1) and its receptors PKR1 and PKR2 are expressed in mouse placenta throughout gestation. EG-VEGF is mainly localised in the labyrinth layer (highest before E10.5 dpc), while PKR1 protein co-localises with EG-VEGF in the labyrinth and PKR2 is maintained over E10.5 dpc with both trophoblastic and endothelial cell localisations, indicating differential receptor engagement in distinct cell types.\",\n      \"method\": \"Mouse placental tissue; immunohistochemistry; qRT-PCR; Western blot at multiple gestational timepoints\",\n      \"journal\": \"Placenta\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 3 / Moderate — direct localization experiment with temporal specificity across gestation, but no functional intervention; replicated across multiple gestational ages\",\n      \"pmids\": [\"17531315\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2015,\n      \"finding\": \"PPARγ activation (rosiglitazone) increases EG-VEGF secretion and upregulates EG-VEGF, PROKR1, and PROKR2 expression in human trophoblasts and placental explants. PPARγ(-/-) mouse placentas have significantly decreased EG-VEGF levels. EG-VEGF mediates PPARγ effects on placental vascularization (via PROKR1 and PROKR2) and inhibition of trophoblast migration and invasion (via PROKR2).\",\n      \"method\": \"Human primary cytotrophoblasts; HTR-8/SVneo cells; placental explants; PPARγ(+/-) and PPARγ(-/-) mouse placentas; PROKR1/PROKR2 receptor antagonists; proliferation, migration, invasion, vascularization assays\",\n      \"journal\": \"American journal of physiology. Endocrinology and metabolism\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — in vitro, ex vivo, and in vivo (knockout mouse) combined with receptor antagonists to map pathway; multiple orthogonal methods\",\n      \"pmids\": [\"26081281\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2017,\n      \"finding\": \"EG-VEGF increases JEG3 choriocarcinoma cell proliferation, migration, and invasion in 2D and 3D culture systems. Treatment with EG-VEGF receptor antagonists (targeting PROKR1/PROKR2) significantly reduced tumor development and progression in a novel in vivo choriocarcinoma mouse model (JEG3-luciferase injected into gravid SCID-mouse placenta).\",\n      \"method\": \"JEG3 cell line; 2D/3D culture proliferation, migration, invasion assays; PROKR1/PROKR2 antagonist treatment; in vivo placental injection CC mouse model; antibody-array and immunohistochemistry\",\n      \"journal\": \"Clinical cancer research\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — in vitro and in vivo receptor antagonism with mechanistic follow-up; single lab but multiple complementary approaches\",\n      \"pmids\": [\"28899975\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2005,\n      \"finding\": \"EG-VEGF/PK-1 elevates [³H]-thymidine incorporation, activates MAPK, and induces c-jun/fos mRNA expression in luteal endothelial cells (LEC), demonstrating direct mitogenic activity. EG-VEGF/PK-1 also inhibits serum starvation-induced apoptosis in LEC. In bovine luteal steroidogenic cells (which express only PK-R1), EG-VEGF/PK-1 elevated VEGF mRNA expression.\",\n      \"method\": \"Primary luteal endothelial cells; [³H]-thymidine incorporation; MAPK activation assay; RT-PCR for c-jun/fos; apoptosis assay under serum withdrawal; receptor expression characterization\",\n      \"journal\": \"Annals of anatomy\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — multiple functional readouts in primary cells; receptor subtype attribution based on expression profiling rather than knockdown/blockade\",\n      \"pmids\": [\"16320832\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2018,\n      \"finding\": \"Knockdown of EG-VEGF (PROK1) in pancreatic carcinoma cells (PANC-1 and BxPC-3) inhibited cell proliferation, induced G0/G1 cell cycle arrest, and promoted apoptosis. EG-VEGF silencing significantly reduced phosphorylated PI3K, AKT, and mTOR levels, placing EG-VEGF upstream of the PI3K/AKT/mTOR signalling pathway in pancreatic cancer cells.\",\n      \"method\": \"shRNA lentiviral knockdown of PROK1; MTT proliferation assay; flow cytometry (cell cycle and apoptosis); Western blot for p-PI3K, p-AKT, p-mTOR\",\n      \"journal\": \"Biomedicine & pharmacotherapy\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — shRNA loss-of-function with defined pathway readout; single lab, no rescue experiment or receptor identification\",\n      \"pmids\": [\"30551529\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2014,\n      \"finding\": \"EG-VEGF decreases metalloproteinase-2 and -9 activities and increases PGDH (prostaglandin-metabolising enzyme) expression in chorion trophoblast and fetal membrane explants. EG-VEGF and its receptors (PROKR1 and PROKR2) show increased expression in fetal membranes toward term with an abrupt decrease at the onset of labor.\",\n      \"method\": \"Human fetal membrane explants; primary chorion trophoblast cultures; MMP-2/MMP-9 activity assays; PGDH expression measurement; qRT-PCR and protein quantification across gestational timepoints\",\n      \"journal\": \"Biology of reproduction\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — direct functional assays in primary human tissue with defined enzyme activity readouts; single lab\",\n      \"pmids\": [\"25122063\"],\n      \"is_preprint\": false\n    }\n  ],\n  \"current_model\": \"PROK1 (EG-VEGF/PK1) is a secreted cysteine-rich peptide that signals through two G-protein-coupled receptors, PROKR1 and PROKR2, to activate intracellular calcium, MAP kinase/ERK, PI3K/AKT/mTOR, and calcineurin/NFAT pathways; PROKR1 primarily mediates angiogenic and proliferative effects (endothelial cell mitogenesis, trophoblast proliferation via HLX, CTGF induction via Gq-PLC-cSrc-EGFR-ERK), while PROKR2 mediates endothelial permeability and inhibition of trophoblast invasion (via MMP-2/MMP-9 suppression), with PROKR1 localising to primary cilia to transduce ERK-dependent invasion signals; upstream regulators include hCG (via cAMP/CRE) and PPARγ, and the protein additionally drives monocyte differentiation and acts upstream of the PI3K/AKT/mTOR axis in cancer cells.\"\n}\n```","stage2_raw":"{\n  \"mechanistic_narrative\": \"PROK1 (EG-VEGF/prokineticin 1) is a secreted peptide that acts as an angiogenic and cell-fate regulator by binding the two G-protein-coupled receptors PROKR1 and PROKR2, triggering nanomolar transient intracellular calcium flux, p44/42 MAP kinase phosphorylation, and DNA synthesis [#0]. The two receptors partition its activities: PROKR1 transduces angiogenic and proliferative outputs—endothelial proliferation, migration, survival and sprouting [#3], and trophoblast proliferation through the homeobox gene HLX [#5]—whereas PROKR2 mediates endothelial permeability and paracellular transport [#3] and the suppression of trophoblast migration and invasion via reduced MMP-2/MMP-9 production [#2]. In the placental decidua, PROK1 signals through PROKR1 to induce IL-11 via a Gq/11–ERK–calcium–calcineurin/NFAT cascade negatively regulated by RCAN1-4 [#6], and to induce CTGF through a Gq–PLC–cSrc–EGFR–MEK/ERK pathway that promotes trophoblast adhesion and tube formation [#7]; PROKR1 localizes to primary cilia, where ciliogenesis (IFT88-dependent) is required for EG-VEGF–driven ERK activation, MMP induction, and trophoblast invasion [#8]. PROK1 expression and its receptors are induced upstream by hCG via cAMP/CRE elements in the EG-VEGF promoter [#4] and by PPARγ activation [#10]. Beyond reproduction, PROK1 directs bone marrow cells toward the monocyte/macrophage lineage and reprograms monocyte cytokine output [#1], and acts upstream of the PI3K/AKT/mTOR axis to sustain proliferation and survival in pancreatic carcinoma cells [#13], with receptor antagonism limiting choriocarcinoma growth in vivo [#11].\",\n  \"teleology\": [\n    {\n      \"year\": 2002,\n      \"claim\": \"Establishing that PROK1 is a functional ligand for two specific GPCRs answered how this secreted peptide initiates signaling and links it to endothelial mitogenesis.\",\n      \"evidence\": \"Radioligand binding, calcium imaging in CHO cells expressing PROKR1/PROKR2, MAP kinase and DNA synthesis assays in endothelial cells\",\n      \"pmids\": [\"12054613\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Did not separate which receptor drives which downstream output\", \"No structural basis for ligand-receptor recognition\"]\n    },\n    {\n      \"year\": 2005,\n      \"claim\": \"Demonstrating PROK1-driven monocyte/macrophage differentiation and cytokine reprogramming extended its role beyond angiogenesis into immune cell fate.\",\n      \"evidence\": \"In vitro bone marrow differentiation, flow cytometry, cytokine ELISA, tissue binding\",\n      \"pmids\": [\"15908459\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Receptor mediating the myeloid effect not defined by mutagenesis\", \"In vivo relevance not established\"]\n    },\n    {\n      \"year\": 2005,\n      \"claim\": \"Showing direct mitogenic and anti-apoptotic activity on luteal endothelial cells and VEGF induction in steroidogenic cells linked PROK1 to ovarian vascular biology.\",\n      \"evidence\": \"Primary luteal endothelial cells; thymidine incorporation, MAPK assay, c-jun/fos RT-PCR, apoptosis under serum withdrawal\",\n      \"pmids\": [\"16320832\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Receptor attribution based on expression profiling not knockdown\", \"No in vivo confirmation\"]\n    },\n    {\n      \"year\": 2009,\n      \"claim\": \"Dissecting the IL-11 induction pathway defined the PROKR1 intracellular cascade (Gq/11-ERK-Ca2+-calcineurin/NFAT) and its negative regulator RCAN1-4 in decidua.\",\n      \"evidence\": \"PROKR1-Ishikawa cells; pharmacological pathway inhibitors, RCAN1-4 overexpression, lentiviral miRNA knockdown in primary decidua\",\n      \"pmids\": [\"19801577\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Physiological role of decidual IL-11 induction not established in vivo\"]\n    },\n    {\n      \"year\": 2009,\n      \"claim\": \"Receptor-specific knockdown established that PROKR2 mediates PROK1 inhibition of trophoblast invasion through MMP-2/MMP-9 suppression.\",\n      \"evidence\": \"Villous explants and HTR-8/SVneo cells; invasion assays, gelatin zymography, PROKR2 siRNA\",\n      \"pmids\": [\"19602057\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Mechanism linking PROKR2 to MMP transcription not resolved\"]\n    },\n    {\n      \"year\": 2010,\n      \"claim\": \"Receptor-selective siRNA and antibodies partitioned PROK1 angiogenic functions to PROKR1 and permeability functions to PROKR2 in placental endothelium.\",\n      \"evidence\": \"Primary placental microvascular endothelial cells; proliferation/migration/survival/sprouting/permeability assays with PROKR1 vs PROKR2 knockdown and neutralizing antibodies\",\n      \"pmids\": [\"20587779\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Divergent G-protein coupling underlying the receptor split not defined\"]\n    },\n    {\n      \"year\": 2010,\n      \"claim\": \"Mapping CTGF induction through Gq-PLC-cSrc-EGFR-ERK defined how PROKR1 promotes trophoblast adhesion and tube formation.\",\n      \"evidence\": \"PROKR1-Ishikawa cells and decidua; pathway inhibitors, miRNA knockdown, adhesion and matrigel assays\",\n      \"pmids\": [\"21098624\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Direct EGFR transactivation mechanism not biochemically resolved\"]\n    },\n    {\n      \"year\": 2011,\n      \"claim\": \"Identifying hCG as an upstream inducer via cAMP/CRE elements placed PROK1 within hormonal control of placentation.\",\n      \"evidence\": \"Placental explants and trophoblasts; qPCR, Western, promoter-reporter, cAMP measurement, pathway inhibition\",\n      \"pmids\": [\"22138749\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Specific CRE sites not validated by mutagenesis\"]\n    },\n    {\n      \"year\": 2012,\n      \"claim\": \"Linking PROK1-driven trophoblast proliferation to HLX through PROKR1 identified a downstream transcriptional effector of the proliferative branch.\",\n      \"evidence\": \"Placental explants; thymidine incorporation, Ki67, receptor-specific siRNA, HLX measurement\",\n      \"pmids\": [\"22941044\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"How PROKR1 signaling regulates HLX transcriptionally not defined\"]\n    },\n    {\n      \"year\": 2014,\n      \"claim\": \"Showing PROK1 decreases MMP-2/9 activity and raises PGDH in fetal membranes with gestational dynamics connected it to fetal membrane remodeling and labor onset.\",\n      \"evidence\": \"Human fetal membrane and chorion trophoblast explants; MMP activity assays, PGDH and receptor expression across gestation\",\n      \"pmids\": [\"25122063\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Causal role in labor timing not tested\", \"Receptor specificity not dissected\"]\n    },\n    {\n      \"year\": 2015,\n      \"claim\": \"Integrating PPARγ as an upstream activator using knockout mice and antagonists positioned PROK1 as a downstream effector of PPARγ in placental vascularization and invasion control.\",\n      \"evidence\": \"Human trophoblasts and explants, PPARγ-null mouse placentas, PROKR1/PROKR2 antagonists across proliferation/migration/invasion/vascularization assays\",\n      \"pmids\": [\"26081281\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Direct PPARγ binding to the EG-VEGF locus not shown\"]\n    },\n    {\n      \"year\": 2016,\n      \"claim\": \"Localizing PROKR1 to primary cilia and showing IFT88-dependence of ERK/MMP activation revealed a ciliary requirement for the invasion-promoting branch.\",\n      \"evidence\": \"HTR-8/SVneo cells; immunofluorescence, IFT88 siRNA, ERK inhibition, invasion assays, MMP Western blots\",\n      \"pmids\": [\"27736039\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"How ciliary localization couples PROKR1 to ERK not defined\", \"Single lab\"]\n    },\n    {\n      \"year\": 2017,\n      \"claim\": \"Demonstrating receptor antagonism reduces choriocarcinoma growth in an in vivo model established PROK1 signaling as a therapeutic target in trophoblastic tumors.\",\n      \"evidence\": \"JEG3 cells; 2D/3D proliferation/migration/invasion, PROKR1/PROKR2 antagonists, in vivo placental injection model\",\n      \"pmids\": [\"28899975\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Relative contributions of PROKR1 vs PROKR2 to tumor effect not separated\"]\n    },\n    {\n      \"year\": 2018,\n      \"claim\": \"Placing PROK1 upstream of PI3K/AKT/mTOR in pancreatic carcinoma extended its proliferative/survival signaling role to a non-reproductive cancer.\",\n      \"evidence\": \"shRNA knockdown in PANC-1/BxPC-3; proliferation, cell cycle, apoptosis assays, phospho-PI3K/AKT/mTOR Western blots\",\n      \"pmids\": [\"30551529\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"No rescue experiment\", \"Receptor mediating the effect not identified\"]\n    },\n    {\n      \"year\": null,\n      \"claim\": \"The molecular basis for divergent PROKR1 vs PROKR2 G-protein coupling and the structural determinants of ligand-receptor selectivity remain unresolved.\",\n      \"evidence\": \"\",\n      \"pmids\": [],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"No structural model of PROK1 bound to either receptor\", \"Mechanism dictating receptor-specific downstream outputs unknown\"]\n    }\n  ],\n  \"mechanism_profile\": {\n    \"molecular_activity\": [\n      {\"term_id\": \"GO:0048018\", \"supporting_discovery_ids\": [0, 3]},\n      {\"term_id\": \"GO:0060089\", \"supporting_discovery_ids\": [0]}\n    ],\n    \"localization\": [\n      {\"term_id\": \"GO:0005576\", \"supporting_discovery_ids\": [0, 3]},\n      {\"term_id\": \"GO:0005929\", \"supporting_discovery_ids\": [8]}\n    ],\n    \"pathway\": [\n      {\"term_id\": \"R-HSA-162582\", \"supporting_discovery_ids\": [0, 6, 7]},\n      {\"term_id\": \"R-HSA-1266738\", \"supporting_discovery_ids\": [3, 9, 10]},\n      {\"term_id\": \"R-HSA-1474165\", \"supporting_discovery_ids\": [2, 4, 5]},\n      {\"term_id\": \"R-HSA-168256\", \"supporting_discovery_ids\": [1]}\n    ],\n    \"complexes\": [],\n    \"partners\": [\"PROKR1\", \"PROKR2\"],\n    \"other_free_text\": []\n  }\n}","audit_flag":null,"evaluation":{"pairwise":"win","faith_supported":5,"faith_total":5,"faith_pct":100.0}}