{"gene":"PRKD1","run_date":"2026-06-10T06:43:35","timeline":{"discoveries":[{"year":1995,"finding":"PKD (PRKD1) is a novel phorbol ester and diacylglycerol-stimulated serine/threonine protein kinase. A bacterially expressed NH2-terminal domain exhibited high affinity phorbol ester binding (Kd = 35 nM). The catalytic domain phosphorylates the peptide substrate syntide-2 on serine. Phorbol esters and diacylglycerol in the presence of phospholipids stimulate syntide-2 kinase activity and autophosphorylation in COS cells. Substrate specificity differs from PKC family members.","method":"In vitro kinase assay with synthetic peptide substrates, phorbol ester binding assay with bacterially expressed domain, COS-7 cell transfection and immunoprecipitation kinase assay","journal":"The Journal of biological chemistry","confidence":"High","confidence_rationale":"Tier 1 / Strong — reconstituted in vitro kinase assay with substrate and mutagenesis of substrate, replicated across multiple orthogonal methods in founding characterization paper","pmids":["7836415"],"is_preprint":false},{"year":1996,"finding":"PKD is activated in living cells through a PKC-dependent signal transduction pathway. Phorbol esters, membrane-permeant DAG, and serum growth factors rapidly induced PKD activation. PKC inhibitors (GF I and Ro 31-8220) completely abrogated cellular PKD activation but did not inhibit PKD activity when added directly in vitro. Co-transfection with constitutively active PKCε and PKCη (but not PKCζ) strongly induced PKD activation in COS-7 cells via phosphorylation.","method":"Intact cell activation assays, immunopurified kinase activity, co-transfection with constitutively active PKC mutants, alkaline phosphatase reversal of activation, pharmacological PKC inhibition","journal":"The EMBO journal","confidence":"High","confidence_rationale":"Tier 2 / Strong — multiple orthogonal methods (pharmacological inhibition, constitutively active mutants, cell-free reversal), replicated across multiple cell types","pmids":["8947045"],"is_preprint":false},{"year":1996,"finding":"PKCμ (PRKD1) associates with the B cell antigen receptor (BCR) complex, co-precipitating with Syk and PLCγ1/2. BCR cross-linking activates PKCμ in a Syk-dependent and partially Btk-dependent manner. In vitro phosphorylation showed Syk and PLCγ1 are potential PKCμ substrates. PKCμ can down-regulate Syk-mediated phosphorylation of PLCγ1 in vitro, suggesting a negative feedback role.","method":"Co-immunoprecipitation from B cells, in vitro kinase assay with fusion protein substrates, DT40 B cell mutant analysis (genetic epistasis)","journal":"Immunity","confidence":"High","confidence_rationale":"Tier 2 / Moderate — reciprocal co-IP, in vitro kinase assay with substrates, genetic epistasis using defined mutant cell lines","pmids":["8885868"],"is_preprint":false},{"year":1999,"finding":"PKD directly phosphorylates threonines T654 and T669 of the EGF receptor. PDGF (but not EGF) activates PKD in Rat-1 cells. PKD-mediated dual phosphorylation of EGFR T654/T669 suppresses EGF-induced JNK activation. An EGFR mutant (T654/669E) mimicking phosphorylation was incapable of activating JNK. Overexpression of PKD in glioblastoma cells blocked EGF- and PDGF-induced JNK activation.","method":"Site-directed mutagenesis of EGFR phosphorylation sites, overexpression of PKD, JNK activity assays, cell-type specific PKD activation assays","journal":"The EMBO journal","confidence":"High","confidence_rationale":"Tier 1 / Moderate — mutagenesis of substrate phosphorylation sites combined with functional readout (JNK activation), multiple cell-line validation","pmids":["10523301"],"is_preprint":false},{"year":1999,"finding":"PKD/PKCμ translocates from cytosol to plasma membrane upon phorbol ester treatment in a cysteine-rich domain (CRD)-dependent manner, as visualized by GFP-PKD fusion protein in real time. A single amino acid substitution (P287G) in the second cysteine-rich motif prevented PDB-induced membrane translocation without affecting PKD kinase activation, demonstrating that PKD translocation and activation are dissociable processes.","method":"Real-time live cell imaging of GFP-PKD fusion protein, site-directed mutagenesis of CRD domain, kinase activity assay","journal":"FEBS letters","confidence":"High","confidence_rationale":"Tier 2 / Moderate — live imaging with functional GFP fusion, point mutagenesis dissecting translocation from activation, single lab","pmids":["10471840"],"is_preprint":false},{"year":2000,"finding":"PKD is present in the cytosol of quiescent B cells and mast cells and rapidly translocates to the plasma membrane upon antigen receptor triggering. Membrane redistribution requires the DAG-binding domain but is independent of catalytic activity and PH domain integrity. Membrane targeting is transient (returns to cytosol within 10 min), yet the membrane-recycled PKD remains active in the cytosol for several hours, establishing spatiotemporal dissemination of antigen receptor signals.","method":"Subcellular fractionation, kinase activity assays, domain deletion mutants, antigen receptor triggering in B cells and mast cells","journal":"The EMBO journal","confidence":"High","confidence_rationale":"Tier 2 / Moderate — domain deletion mutants combined with fractionation and kinase assays in primary immune cells, multiple orthogonal methods","pmids":["10856238"],"is_preprint":false},{"year":2001,"finding":"PKD binds diacylglycerol (DAG) and this binding is necessary for its recruitment to the trans-Golgi network (TGN). Reducing cellular DAG levels inhibited PKD recruitment and blocked protein transport from the TGN to the cell surface. PKD regulates the fission of transport carriers destined to the cell surface from the TGN.","method":"DAG manipulation (pharmacological and genetic reduction), PKD localization assay at TGN, protein transport assays to cell surface","journal":"Science","confidence":"High","confidence_rationale":"Tier 2 / Strong — multiple orthogonal approaches (DAG reduction, localization, transport assay), replicated in subsequent studies","pmids":["11729268"],"is_preprint":false},{"year":2001,"finding":"PKCη directly phosphorylates PKD (PKCμ) activation loop serines (Ser738/742) in vitro, leading to PKD activation. PKD colocalizes with PKCη in a PH domain-dependent manner. PKCη-mediated PKD activation stimulates p42 MAPK/ERK cascade and reporter gene transcription via SRE, while simultaneously reducing PKCη-mediated JNK activation.","method":"In vitro phosphorylation assay showing PKCη phosphorylates PKD activation loop, confocal colocalization, co-expression of constitutively active PKCη, kinase substrate phosphorylation assay, reporter gene assay","journal":"The Journal of biological chemistry","confidence":"High","confidence_rationale":"Tier 1 / Moderate — direct in vitro phosphorylation assay identifying PKCη as writer for PKD activation loop, combined with cell-based functional readouts","pmids":["11741879"],"is_preprint":false},{"year":2001,"finding":"PKD is rapidly activated in intestinal epithelial cells (IEC-6, IEC-18) by phorbol esters, lysophosphatidic acid (LPA), and angiotensin II through a PKC-dependent pathway. LPA-induced PKD activation is prevented by pertussis toxin, indicating Gi coupling. PKD activation is tightly associated with autophosphorylation at serine 916. PKD does not undergo downregulation after prolonged phorbol ester treatment, unlike conventional/novel PKCs.","method":"Intact cell kinase assays, PKC inhibitor treatment, pertussis toxin treatment, autophosphorylation detection at Ser916","journal":"American journal of physiology. Cell physiology","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — pharmacological dissection of pathway with multiple agonists, identification of Ser916 autophosphorylation, single lab","pmids":["11245610"],"is_preprint":false},{"year":2002,"finding":"Golgi localization of PKCμ (PRKD1) requires both the NH2-terminal hydrophobic region and the cysteine-rich region; deletion of either completely abrogates Golgi localization. The NH2-terminal PKCμ fragment is sufficient for Golgi membrane association. Golgi recruitment is constitutive, rapid, and independent of activation loop phosphorylation or kinase activity. A sequential activation process occurs: Golgi recruitment precedes and is required for activation loop phosphorylation (Ser738/742) by a trans-acting kinase, followed by auto- and transphosphorylation of NH2-terminal serines.","method":"Confocal microscopy of GFP-fusion deletion mutants in HeLa cells, FRAP analysis, cell fractionation, phospho-specific western blot","journal":"The Journal of cell biology","confidence":"High","confidence_rationale":"Tier 2 / Moderate — multiple domain deletion mutants with FRAP, fractionation, and phospho-specific antibodies, multiple orthogonal methods in single rigorous study","pmids":["11777941"],"is_preprint":false},{"year":2002,"finding":"PKD (PKCμ) is expressed in human platelets and rapidly activated by receptors coupled to heterotrimeric G-proteins or tyrosine kinases. PKD activation in platelets is mediated downstream of PKC. Strong agonists (convulxin via GPVI, thrombin) cause sustained PKD activation; thromboxane mimetic U46619 causes transient activation. Gi-coupled receptor agonists potentiate PKD activation by submaximal PLC-coupled agonist concentrations.","method":"Platelet activation assays with multiple agonists, PKC inhibitor treatment, kinase activity measurement","journal":"Blood","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — pharmacological epistasis with multiple agonist classes in primary human cells, single lab","pmids":["12393506"],"is_preprint":false},{"year":2005,"finding":"PKD is activated specifically by G protein subunits β1γ2 and β3γ2 via the Golgi apparatus-associated PKCη. PKD is activated at the TGN through a Gβγ→PKCη→PKD axis. Compromising PKCη kinase activity inhibits protein transport from TGN to cell surface. Constitutively active PKCη caused Golgi fragmentation that was inhibited by kinase-inactive PKD, placing PKD downstream of PKCη in the vesicle-generating pathway.","method":"Dominant-negative and constitutively active kinase constructs, Golgi fragmentation assay, protein transport assay, epistasis by kinase-dead PKD","journal":"The Journal of cell biology","confidence":"High","confidence_rationale":"Tier 2 / Strong — epistatic ordering of Gβγ→PKCη→PKD with multiple dominant-negative and constitutively active constructs, replicated in subsequent work","pmids":["15824133"],"is_preprint":false},{"year":2006,"finding":"The C1b domain of PKD isoforms binds phorbol esters with high affinity, while the C1a domain has non-consensus residues that mainly contribute to structural fold rather than ligand binding. C1a and C1b in intact C1a-C1b of PKD1 show opposite selectivity for phorbol esters (PDBu) and DAG (DOG). A conserved lysine at position 22 in C1b accounts for weaker DAG affinity. Mutation of C1a in full-length PKD3-GFP reduces DOG-induced plasma membrane translocation but not PMA-induced translocation.","method":"Radioligand binding assay with [3H]PDBu, site-directed mutagenesis of C1 domain residues, GFP-PKD translocation assay in living cells","journal":"The Biochemical journal","confidence":"High","confidence_rationale":"Tier 1 / Moderate — in vitro binding assays with mutagenesis combined with live cell translocation imaging, multiple orthogonal methods","pmids":["18076381"],"is_preprint":false},{"year":2007,"finding":"PLCβ3 is the specific phospholipase C isoform required for PKD1 activation at the TGN. Gβγ-dependent Golgi fragmentation, PKD1 activation loop phosphorylation, and TGN-to-plasma membrane transport were inhibited by a PI-PLC inhibitor (U73122) and by siRNA knockdown of PLCβ3 (but not other PI-PLC isoforms). A PI-PLC activator (m-3M3FBS) induced Golgi vesiculation and PKD1 activation loop phosphorylation. PLCβ3 acts upstream of PKCη and PKD in the vesicle-generating pathway by producing DAG.","method":"siRNA knockdown of individual PLCβ isoforms, pharmacological PI-PLC inhibition and activation, PKD1 activation loop phosphorylation western blot, TGN-to-plasma membrane transport assay","journal":"The Biochemical journal","confidence":"High","confidence_rationale":"Tier 2 / Moderate — siRNA isoform-selective knockdown combined with pharmacological modulation and functional transport assay, multiple orthogonal methods","pmids":["17492941"],"is_preprint":false},{"year":2007,"finding":"PKD depletion by siRNA inhibits TGN-to-cell surface trafficking, while expression of constitutively active PKD converts TGN into small vesicles. PKD is required for membrane fission to generate transport carriers, and this activity controls the size of transport carriers and prevents uncontrolled vesiculation of TGN. PKD functions as a dimer at the TGN for membrane fission.","method":"siRNA depletion of PKD, constitutively active PKD expression, electron microscopy and fluorescence microscopy of Golgi morphology, protein transport assays","journal":"The Journal of cell biology","confidence":"High","confidence_rationale":"Tier 2 / Strong — loss-of-function (siRNA) and gain-of-function (constitutively active) with morphological readout, replicated across studies","pmids":["18086912"],"is_preprint":false},{"year":2007,"finding":"PKD is recruited to the leading edge of migrating cells where it co-localizes with F-actin, Arp3, and cortactin. PDGF activates PKD and recruits it to the leading edge. PKD directly interacts with F-actin and phosphorylates cortactin in vitro. Dominant-negative PKD or PKD siRNA enhanced cell migration, while wild-type PKD overexpression reduced migration, establishing a negative regulatory function of PKD in cell migration.","method":"Confocal co-localization, in vitro pulldown with F-actin, in vitro kinase assay for cortactin phosphorylation, dominant-negative overexpression, siRNA knockdown, migration assay","journal":"FEBS letters","confidence":"High","confidence_rationale":"Tier 1 / Moderate — in vitro kinase assay identifying cortactin as substrate combined with loss-of-function (siRNA, dominant-negative) migration phenotype and F-actin interaction","pmids":["17707375"],"is_preprint":false},{"year":2008,"finding":"PKD phosphorylates type IIα PIP kinase on activation loop threonine T376, inhibiting enzyme activity. A phospho-specific antibody confirmed T376 phosphorylation in living cells, enhanced when PKD was activated. Mutation of T376 to aspartate (phosphomimetic) significantly inhibited PIP kinase activity. PKD was identified as the responsible kinase by pharmacological studies and in vitro confirmation.","method":"In vitro phosphorylation assay, phospho-specific antibody, site-directed mutagenesis of T376, pharmacological PKD inhibition in cells","journal":"Cellular signalling","confidence":"High","confidence_rationale":"Tier 1 / Moderate — in vitro kinase assay identifying T376 as PKD phosphorylation site, mutagenesis confirming functional effect, phospho-specific antibody validation in cells","pmids":["16563698"],"is_preprint":false},{"year":2008,"finding":"PKD and PKD2 mediate neurotensin-induced phosphorylation of Hsp27 at Ser-82 in PANC-1 pancreatic cancer cells through a PKC-dependent pathway. siRNA knockdown of PKD or PKD2 individually reduced Hsp27 Ser-82 phosphorylation; combined knockdown of both virtually abolished it. This pathway operates in parallel to p38 MAPK-mediated Hsp27 phosphorylation.","method":"siRNA knockdown of PKD and PKD2, phospho-specific western blot for Hsp27 Ser-82, pharmacological inhibition of PKC and p38 MAPK, PKD overexpression in stably transfected cells","journal":"Journal of cellular biochemistry","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — siRNA knockdown of two isoforms combined with pharmacological dissection and overexpression, single lab","pmids":["17570131"],"is_preprint":false},{"year":2009,"finding":"A Golgi-targeted PKD activity reporter (PKD-specific substrate fused to EGFP targeted to TGN via p230 GRIP domain) revealed that nocodazole-induced Golgi dispersal is associated with local PKD activation. Dominant-negative PKD or PKD siRNA depletion blocked nocodazole-induced Golgi break-up, identifying a link between PKD activity and microtubule cytoskeleton in regulating Golgi complex integrity.","method":"Genetically encoded Golgi-targeted PKD activity reporter, phospho-specific antibody validation, ratiometric fluorescence imaging, dominant-negative PKD expression, siRNA knockdown, nocodazole treatment","journal":"Traffic","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — validated molecular reporter with loss-of-function confirmation, single lab","pmids":["19416469"],"is_preprint":false},{"year":2009,"finding":"p38δ MAPK catalyzes an inhibitory phosphorylation of PKD1, thereby attenuating stimulated insulin secretion from pancreatic β cells. Deletion of p38δ results in pronounced PKD activation and enhanced insulin exocytosis. Inhibition of PKD1 reverses enhanced insulin secretion in p38δ-deficient islets. The p38δ-PKD1 pathway integrates regulation of insulin secretory capacity and β cell survival.","method":"p38δ knockout mice, PKD1 inhibition in isolated islets, glucose tolerance tests, in vivo and ex vivo insulin secretion measurements, genetic epistasis (p38δ KO + PKD1 inhibition)","journal":"Cell","confidence":"High","confidence_rationale":"Tier 2 / Strong — genetic knockout combined with pharmacological rescue, epistatic ordering of p38δ→PKD1 in insulin secretion, published in high-impact journal with multiple orthogonal approaches","pmids":["19135240"],"is_preprint":false},{"year":2011,"finding":"PKD phosphorylates Vps34 (a lipid kinase), leading to Vps34 activation, PI(3)P formation, and autophagosome formation in response to oxidative stress. PKD is found in the same molecular complex with Vps34 by co-immunoprecipitation. PKD is activated by DAPk (death-associated protein kinase) upstream in this cascade. PKD is recruited to LC3-positive autophagosomal membranes.","method":"Co-immunoprecipitation of PKD-Vps34 complex, PI(3)P measurement, autophagosome formation assay (LC3 puncta), epistasis with DAPk, PKD localization to autophagosomes","journal":"Cell death and differentiation","confidence":"High","confidence_rationale":"Tier 2 / Moderate — co-IP identifying complex, functional PI(3)P production assay, autophagosome localization, epistatic ordering of DAPk→PKD→Vps34","pmids":["22095288"],"is_preprint":false},{"year":2011,"finding":"PKD1 promotes NF-κB activation and suppresses p38 MAPK in response to H2O2 in intestinal epithelial cells, thereby protecting against apoptosis. PKD1 siRNA inhibited H2O2-induced NF-κB activation, p65 translocation, and IκBα phosphorylation. Wild-type PKD1 overexpression reduced p38 MAPK and MKK3/6 phosphorylation, while kinase-dead PKD1 increased it. PKD1 does not affect ERK1/2 or JNK phosphorylation.","method":"siRNA knockdown, overexpression of wild-type and kinase-dead PKD1, phospho-specific western blots for NF-κB pathway components and MAPKs, NF-κB translocation assay","journal":"Biochemical and biophysical research communications","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — loss-of-function (siRNA) and gain-of-function with kinase-dead control, single lab, multiple pathway readouts","pmids":["19059215"],"is_preprint":false},{"year":2011,"finding":"PKD mediates PDGF-dependent αvβ3 integrin recycling through phosphorylation of Rabaptin-5 at Ser407. PKD phosphorylation of Rabaptin-5 Ser407 is necessary and sufficient for PDGF-dependent short-loop αvβ3 recycling and inhibition of α5β1 recycling. Rab4 (not Rab5) interacts with phosphorylated Rabaptin-5 at the leading edge to promote αvβ3 delivery, driving persistent cell motility and invasion.","method":"In vitro kinase assay identifying Rabaptin-5 Ser407 as PKD substrate, phospho-specific antibody, Rab4/Rab5 co-immunoprecipitation with phospho-Rabaptin-5, mutagenesis of Ser407, integrin recycling assay, 2D migration and 3D invasion assay","journal":"Developmental cell","confidence":"High","confidence_rationale":"Tier 1 / Moderate — in vitro kinase assay with substrate identification, phospho-specific antibody validation, Ser407 mutagenesis with functional rescue, integrin trafficking readout","pmids":["22975325"],"is_preprint":false},{"year":2011,"finding":"PKD activates PI4KIIIβ (phosphatidylinositol 4-kinase IIIβ) at the TGN to promote PI4P production. PI4P then recruits OSBP and CERT which control sphingolipid and sterol levels. PKD subsequently phosphorylates OSBP and CERT to dissociate them from TGN. This drives sequential DAG→PA→LPA lipid conversion necessary for membrane fission to generate cell surface transport carriers.","method":"Review synthesizing biochemical evidence from preceding studies; includes lipid kinase activation and substrate phosphorylation evidence","journal":"Cold Spring Harbor perspectives in biology","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — mechanistic synthesis of established biochemical data on PI4KIIIβ activation and CERT/OSBP phosphorylation by PKD, review format but citing primary experiments","pmids":["21421913"],"is_preprint":false},{"year":2012,"finding":"PKD controls mitotic Golgi fragmentation via a Raf-MEK1 pathway. siRNA depletion of PKD1 and PKD2 causes G2 cell cycle arrest and prevents mitosis entry. PKD inhibition blocks mitotic Raf-1 and MEK activation, and consequently mitotic Golgi fragmentation; expression of active MEK1 rescues the PKD-depleted phenotype. FRAP analysis showed PKD is crucial for cleavage of non-compact Golgi membrane zones in G2 phase.","method":"siRNA depletion of PKD1/PKD2, cell cycle analysis, Raf/MEK activation western blot, constitutively active MEK1 rescue, Golgi FRAP analysis","journal":"Molecular biology of the cell","confidence":"High","confidence_rationale":"Tier 2 / Moderate — epistatic rescue of MEK1 expression downstream of PKD depletion, combined with FRAP and cell cycle analysis, multiple orthogonal methods","pmids":["23242995"],"is_preprint":false},{"year":2013,"finding":"PRKD1 promoter is aberrantly methylated and silenced in invasive breast cancer cells. Re-expression of PKD1 via decitabine (DNA methyltransferase inhibitor) restores PKD1 expression and blocks tumor metastasis to the lung in a xenograft model in a PKD1-dependent manner. PKD1 expression maintains the epithelial phenotype by preventing EMT in normal mammary gland cells.","method":"Methylation-specific PCR, bisulfite deep sequencing, decitabine treatment in vitro and in vivo xenograft model, transwell invasion assay, in vivo bioluminescence imaging of metastasis","journal":"Breast cancer research","confidence":"High","confidence_rationale":"Tier 2 / Moderate — in vivo xenograft rescue experiment with PKD1-dependent metastasis suppression, combined with multiple methylation detection methods","pmids":["23971832"],"is_preprint":false},{"year":2013,"finding":"Nerve injury-induced GDNF upregulation in Schwann cells is mediated by a purinergic receptor→PKC→PKD signaling cascade. Activation of Schwann cell purinergic receptors leads to PKC activation, which activates PKD, which drives increased GDNF transcription.","method":"Pharmacological inhibition of PKC and PKD, siRNA knockdown, GDNF expression assays in Schwann cells following nerve injury model","journal":"Glia","confidence":"Medium","confidence_rationale":"Tier 2 / Weak — pharmacological and siRNA-based pathway dissection, single lab, limited mechanistic detail in abstract","pmids":["23553603"],"is_preprint":false},{"year":2014,"finding":"PRKD1 hotspot somatic mutation E710D (p.Glu710Asp) is a kinase-activating alteration found in 72.9% of polymorphous low-grade adenocarcinomas (PLGAs) of salivary glands but not in other salivary gland tumors. Functional studies demonstrated this mutation constitutively activates PRKD1 kinase activity, likely acting as a driver of PLGA.","method":"Tumor sequencing, functional characterization of kinase activity of E710D mutant vs wild-type","journal":"Nature genetics","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — functional kinase activity assay confirming activating nature of mutation, large tumor cohort, but limited mechanistic detail in abstract","pmids":["25240283"],"is_preprint":false},{"year":2015,"finding":"PRKD1 is a direct transcriptional target of Twist1 and is not expressed in normal mammary epithelium. Prkd1 is required for Twist1-induced epithelial dissemination: pharmacological and genetic Prkd1 inhibition blocks ECM-directed protrusions, epithelial release, and migration through ECM. Prkd1 induces phosphorylation of β-catenin (inactivating) and Tau (microtubule-depolymerizing) as part of its dissemination program. Prkd1 knockdown in vivo blocked primary tumor invasion and distant metastasis.","method":"3D mammary organoid culture model, Twist1 overexpression, Prkd1 pharmacological inhibition and shRNA knockdown, ChIP-PCR confirming direct Twist1 binding to Prkd1 promoter, antibody-based phosphoproteomics, in vivo mouse tumor model","journal":"Cancer research","confidence":"High","confidence_rationale":"Tier 2 / Strong — ChIP-PCR confirming direct transcriptional target, loss-of-function rescue in 3D and in vivo, phosphoproteomic substrate identification, multiple orthogonal methods","pmids":["31676574"],"is_preprint":false},{"year":2015,"finding":"GPCR activation induces biphasic YAP regulation in intestinal epithelial cells through PKD family kinases. PKD family inhibitors or siRNA-mediated knockdown of PKD1/PKD2/PKD3 prevented YAP phosphorylation at Ser127 and Ser397 via Lats2, cytoplasmic accumulation of YAP, and induction of YAP/TEAD-regulated genes (CTGF and Areg) in response to angiotensin II, vasopressin, or serum.","method":"PKD family inhibitors (CRT0066101, kb NB 142-70), siRNA knockdown of PKD1/2/3, phospho-specific western blot for YAP, nuclear-cytoplasmic fractionation, qRT-PCR of YAP target genes","journal":"The Journal of biological chemistry","confidence":"High","confidence_rationale":"Tier 2 / Moderate — both pharmacological and genetic (siRNA triple knockdown) loss-of-function with multiple pathway readouts, single lab","pmids":["27369082"],"is_preprint":false},{"year":2015,"finding":"PKD1 promotes neutrophil chemotaxis through the GPCR→PLCγ2(PI3K-dependent)→PKCβ→PKD1→SSH2 signaling axis. PKCβ specifically interacts with PKD1 and is required for chemotaxis. PKD1 phosphorylates slingshot phosphatase 2 (SSH2), which regulates cofilin phosphorylation and actin cytoskeletal reorganization.","method":"siRNA knockdown of pathway components, co-immunoprecipitation of PKCβ-PKD1 interaction, in vitro kinase assay for SSH2 phosphorylation, cofilin phosphorylation western blot, chemotaxis assay","journal":"Molecular biology of the cell","confidence":"High","confidence_rationale":"Tier 1 / Moderate — in vitro kinase assay identifying SSH2 as PKD1 substrate, co-IP of PKCβ-PKD1 interaction, siRNA epistasis in neutrophil chemotaxis","pmids":["25568344"],"is_preprint":false},{"year":2016,"finding":"LPA-mediated CD36 transcriptional repression by PKD-1 involves PKD-1 signaling-mediated formation of a FoxO1-HDAC7 complex in the nucleus. PKD-1 promotes nuclear accumulation of HDAC7, where it interacts with FoxO1 to suppress endothelial CD36 transcription, leading to proangiogenic reprogramming including ephrin B2 expression.","method":"Avidin-biotin-conjugated DNA-binding assay, chromatin immunoprecipitation, co-immunoprecipitation of FoxO1-HDAC7 complex, proximal ligation assay, immunofluorescence, gene transfection, spheroid angiogenesis assay, in vivo Matrigel angiogenesis","journal":"Arteriosclerosis, thrombosis, and vascular biology","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — co-IP, ChIP, and DNA-binding assay identifying nuclear FoxO1-HDAC7 complex downstream of PKD-1, single lab with multiple methods","pmids":["27013613"],"is_preprint":false},{"year":2018,"finding":"A Rho signaling network comprising GEF-H1, the RhoGAP DLC3, and the Rho effector PLCε regulates PKD activation at trans-Golgi membranes. This molecular network coordinates formation of TGN-derived Rab6-positive transport carriers for localized exocytosis at focal adhesions.","method":"Genetically encoded PKD activity reporter (G-PKDrep), siRNA knockdown of Rho pathway components (GEF-H1, DLC3, PLCε), live cell imaging of Rab6 transport carriers, focal adhesion exocytosis assay","journal":"eLife","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — validated molecular reporter for PKD activity combined with siRNA epistasis, single lab","pmids":["30028295"],"is_preprint":false},{"year":2021,"finding":"PKD directly phosphorylates the mitochondrial fission factor MFF specifically during mitosis. PKD-dependent MFF phosphorylation is required and sufficient for mitochondrial fission in mitotic (but not interphase) cells. Phosphorylation of MFF by PKD is crucial for chromosome segregation and promotes cell survival by inhibiting adaptation of the mitotic checkpoint.","method":"In vitro kinase assay identifying MFF as PKD substrate during mitosis, phospho-specific antibody, expression of phospho-mimetic and phospho-dead MFF mutants, chromosome segregation assay, mitotic checkpoint analysis","journal":"Cell reports","confidence":"High","confidence_rationale":"Tier 1 / Moderate — in vitro kinase assay identifying MFF as PKD substrate, mutagenesis of phosphorylation site with functional readout for mitosis and chromosome segregation","pmids":["34010649"],"is_preprint":false},{"year":2022,"finding":"PKD directly phosphorylates PARP12 at the TGN, which is essential to stimulate PARP12 catalytic activity. Activated PARP12 then mono-ADP-ribosylates Golgin-97 at an acidic cluster in its coiled-coil domain, which is required for E-cadherin and VSVG carrier fission and transport from TGN to plasma membrane. PARP12/Golgin-97 ADP-ribosylation is selective for Golgin-97-dependent (not Golgin-245-dependent) basolateral cargo transport.","method":"In vitro kinase assay showing PKD phosphorylates PARP12, in vitro ADP-ribosylation assay of Golgin-97 by PARP12, mutagenesis of Golgin-97 acidic cluster and PARP12 phosphorylation site, cargo transport assay (E-cadherin, VSVG), live imaging of carrier fission","journal":"Proceedings of the National Academy of Sciences","confidence":"High","confidence_rationale":"Tier 1 / Moderate — in vitro kinase assay and in vitro ADP-ribosylation assay with mutagenesis of multiple functional sites, combined with cargo transport readout; multiple orthogonal methods in single study","pmids":["34969853"],"is_preprint":false},{"year":2011,"finding":"Gαq, but not the closely related Gα11, promotes PKD autophosphorylation at Ser748 (activation loop) in a PKC-independent manner. Gα11, Gα14, and Gα15 mediate PKD activation in a PKC-dependent manner. Gαq-specific PKC-independent PKD activation was also demonstrated using Pasteurella multocida toxin (selective Gαq activator) in Swiss 3T3 cells.","method":"COS-7 cell co-transfection with Gq-family Gα subunits, AlF4⁻ activation, PKC inhibitor (GF1) treatment, phospho-specific western blot for Ser744 (PKC transphosphorylation) and Ser748 (autophosphorylation), in vitro kinase assay","journal":"Cellular signalling","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — pharmacological dissection combined with Gα subunit specificity analysis and phospho-site specific readouts, single lab","pmids":["22227248"],"is_preprint":false}],"current_model":"PRKD1 (PKD1/PKCμ) is a DAG- and phorbol ester-activated serine/threonine kinase that is recruited to the trans-Golgi network via DAG binding, where it is sequentially activated by a Gβγ→PLCβ3→PKCη→PKD transphosphorylation cascade and then drives membrane fission to generate basolateral transport carriers through activation of PI4KIIIβ, phosphorylation of CERT/OSBP, and sequential DAG→PA→LPA lipid remodeling; at the TGN PKD also directly phosphorylates PARP12 to catalyze Golgin-97 ADP-ribosylation required for E-cadherin transport, and controls mitotic Golgi fragmentation via a Raf-MEK1 axis; in the cytoplasm it acts downstream of PKC (particularly PKCε/η) to relay GPCR and antigen receptor signals, phosphorylates substrates including the EGFR (T654/T669), Hsp27 (via p38δ-inhibited activation in β cells to regulate insulin secretion), Vps34 (promoting autophagy under oxidative stress), Rabaptin-5 (Ser407, directing αvβ3 integrin recycling and invasive migration), cortactin (negatively regulating actin-based cell migration), MFF (driving mitotic mitochondrial fission essential for chromosome segregation), type IIα PIP kinase (T376, inhibitory), and SSH2 (regulating cofilin and neutrophil chemotaxis); its expression is epigenetically silenced by promoter methylation in invasive breast cancer, and its re-expression suppresses EMT and metastasis while its Twist1-driven induction in cancer promotes epithelial dissemination through β-catenin and Tau phosphorylation."},"narrative":{"mechanistic_narrative":"PRKD1 (PKD/PKCμ) is a diacylglycerol- and phorbol ester-activated serine/threonine kinase that couples lipid second-messenger signaling to membrane trafficking, cytoskeletal dynamics, and cell-fate decisions [PMID:7836415, PMID:11729268]. It is activated in cells through a PKC-dependent relay in which novel PKC isoforms (PKCε/η) transphosphorylate the PKD activation loop (Ser738/742), a step distinct from and downstream of its DAG-driven membrane recruitment [PMID:8947045, PMID:10471840, PMID:11741879]; activation can also proceed through Gq-family and Gβγ-coupled GPCR inputs [PMID:15824133, PMID:22227248]. At the trans-Golgi network, DAG binding recruits PKD where a Gβγ→PLCβ3→PKCη→PKD cascade activates it to drive fission of basolateral transport carriers, acting through PI4KIIIβ activation and CERT/OSBP phosphorylation and through direct phosphorylation of PARP12 that licenses Golgin-97 ADP-ribosylation for E-cadherin transport [PMID:15824133, PMID:17492941, PMID:18086912, PMID:21421913, PMID:34969853]. PKD additionally governs Golgi integrity during the cell cycle via a Raf–MEK1 axis and drives mitotic mitochondrial fission by phosphorylating MFF, a step required for faithful chromosome segregation [PMID:23242995, PMID:34010649]. In the cytoplasm PKD relays GPCR and antigen-receptor signals and phosphorylates a diverse substrate set—EGFR T654/T669 to suppress JNK signaling, Rabaptin-5 Ser407 to direct αvβ3 integrin recycling and invasion, cortactin and SSH2 to control actin-based migration and chemotaxis, and Vps34 to promote autophagy under oxidative stress [PMID:10523301, PMID:17707375, PMID:16563698, PMID:22095288, PMID:22975325, PMID:25568344]. PRKD1 is epigenetically silenced by promoter methylation in invasive breast cancer where it maintains the epithelial phenotype and suppresses metastasis, yet as a direct Twist1 transcriptional target it can also drive epithelial dissemination through β-catenin and Tau phosphorylation; a recurrent activating E710D mutation marks polymorphous low-grade adenocarcinoma of the salivary gland [PMID:23971832, PMID:25240283, PMID:31676574].","teleology":[{"year":1995,"claim":"Established PRKD1 as a distinct DAG/phorbol ester-responsive serine/threonine kinase rather than a conventional PKC, defining its founding biochemical identity.","evidence":"In vitro kinase assays with syntide-2, phorbol ester binding by bacterially expressed N-terminal domain, COS cell autophosphorylation","pmids":["7836415"],"confidence":"High","gaps":["Physiological substrates not yet identified","Cellular activation pathway not yet defined"]},{"year":1996,"claim":"Showed PKD activation in cells is PKC-dependent, placing it downstream of novel PKC isoforms and resolving how DAG signals reach the kinase.","evidence":"Pharmacological PKC inhibition, constitutively active PKCε/η co-transfection, cell-free reversal in COS-7 cells","pmids":["8947045"],"confidence":"High","gaps":["Direct phosphorylation site on PKD not yet mapped","Identity of the upstream kinase at endogenous sites unconfirmed in 1996"]},{"year":1996,"claim":"Linked PKD to antigen receptor signaling by showing it associates with and modulates the BCR/Syk/PLCγ module, extending its role into immune-receptor relays.","evidence":"Co-IP from B cells, in vitro kinase assays on Syk/PLCγ1, DT40 genetic epistasis","pmids":["8885868"],"confidence":"High","gaps":["In vivo relevance of Syk/PLCγ1 phosphorylation not established","Whether feedback role is physiologically dominant unknown"]},{"year":1999,"claim":"Identified EGFR T654/T669 as direct PKD substrates whose phosphorylation suppresses JNK signaling, giving PKD a defined receptor-modulatory output.","evidence":"EGFR site mutagenesis, PKD overexpression, JNK activity assays in Rat-1 and glioblastoma cells","pmids":["10523301"],"confidence":"High","gaps":["Endogenous stoichiometry of EGFR phosphorylation unknown","Direct in vitro demonstration limited"]},{"year":1999,"claim":"Dissected PKD membrane translocation from kinase activation, establishing the CRD as the targeting module independent of catalytic activity.","evidence":"Real-time GFP-PKD imaging, P287G CRD mutant, kinase assays","pmids":["10471840"],"confidence":"High","gaps":["Lipid ligand specificity of each C1 subdomain not resolved here","Subcellular target of translocation beyond plasma membrane not addressed"]},{"year":2000,"claim":"Demonstrated transient receptor-triggered membrane targeting followed by sustained cytosolic activity, defining how PKD spatiotemporally disseminates antigen-receptor signals.","evidence":"Subcellular fractionation, domain deletion mutants, kinase assays in B cells and mast cells","pmids":["10856238"],"confidence":"High","gaps":["Cytosolic substrates of recycled active PKD not identified","Mechanism sustaining cytosolic activity unclear"]},{"year":2001,"claim":"Defined PKD as a regulator of TGN-to-surface trafficking, recruited by DAG and required for fission of transport carriers.","evidence":"DAG manipulation, TGN localization, protein transport assays","pmids":["11729268"],"confidence":"High","gaps":["Direct fission substrates not yet identified","Carrier cargo selectivity not addressed"]},{"year":2001,"claim":"Mapped PKCη as the direct activation-loop kinase (Ser738/742) for PKD, completing the upstream PKC→PKD writer relationship and linking it to ERK/SRE signaling.","evidence":"In vitro phosphorylation, confocal colocalization, constitutively active PKCη, reporter assays","pmids":["11741879"],"confidence":"High","gaps":["Whether PKCη is the sole physiological activation-loop kinase unknown","Context-specificity versus PKCε not resolved"]},{"year":2001,"claim":"Resolved the Golgi recruitment logic—dual N-terminal hydrophobic plus CRD requirement, constitutive and activation-independent—and ordered recruitment before activation-loop phosphorylation.","evidence":"GFP-fusion deletion mutants, FRAP, fractionation, phospho-specific blots in HeLa","pmids":["11777941"],"confidence":"High","gaps":["Identity of the trans-acting Golgi activation-loop kinase not established here","Lipid versus protein contributions to Golgi anchoring unresolved"]},{"year":2001,"claim":"Extended PKD activation to GPCR/Gi-coupled inputs (LPA, angiotensin II) in epithelial cells and identified Ser916 autophosphorylation as an activity marker.","evidence":"Intact-cell kinase assays, pertussis toxin, Ser916 autophosphorylation detection in IEC cells","pmids":["11245610"],"confidence":"Medium","gaps":["Single lab","Downstream effectors of LPA/AngII-induced PKD not identified"]},{"year":2002,"claim":"Showed PKD is activated downstream of PKC in platelets by GPCR and tyrosine kinase agonists, broadening its receptor-relay role to hemostatic cells.","evidence":"Platelet agonist activation assays, PKC inhibition, kinase activity measurement","pmids":["12393506"],"confidence":"Medium","gaps":["Functional platelet substrates of PKD not identified","Single lab"]},{"year":2005,"claim":"Established the Gβγ→PKCη→PKD axis at the TGN with epistatic ordering, defining the heterotrimeric G-protein input to Golgi carrier formation.","evidence":"Dominant-negative/constitutively active constructs, Golgi fragmentation and transport assays, kinase-dead PKD epistasis","pmids":["15824133"],"confidence":"High","gaps":["Source of Gβγ at the Golgi not defined","Link to PLC isoform not yet identified at this step"]},{"year":2007,"claim":"Identified PLCβ3 as the specific DAG-generating PLC upstream of PKCη/PKD at the TGN, completing the lipid-signaling input to carrier fission.","evidence":"Isoform-selective siRNA, PI-PLC inhibitor/activator, activation-loop phospho-blot, transport assays","pmids":["17492941"],"confidence":"High","gaps":["How PLCβ3 is recruited/activated at the Golgi unclear","Spatial coupling to Gβγ not directly imaged"]},{"year":2007,"claim":"Defined PKD's mechanistic role as a dimeric membrane-fission machine controlling carrier size and preventing uncontrolled TGN vesiculation.","evidence":"siRNA depletion, constitutively active PKD, EM and fluorescence Golgi morphology, transport assays","pmids":["18086912"],"confidence":"High","gaps":["Direct fission-effector substrates not identified in this study","Structural basis of dimeric fission unknown"]},{"year":2007,"claim":"Established PKD as a negative regulator of cell migration acting through cortactin phosphorylation at the leading edge.","evidence":"Confocal colocalization, F-actin pulldown, in vitro cortactin kinase assay, dominant-negative/siRNA migration assays","pmids":["17707375"],"confidence":"High","gaps":["Cortactin phospho-site functional consequence on actin not fully mapped","Reconciliation with pro-invasive roles unclear"]},{"year":2008,"claim":"Identified type IIα PIP kinase T376 as an inhibitory PKD substrate, linking PKD to phosphoinositide pool regulation.","evidence":"In vitro kinase assay, phospho-specific antibody, T376 mutagenesis, pharmacological PKD inhibition","pmids":["16563698"],"confidence":"High","gaps":["Physiological context of PIP kinase inhibition not defined","Downstream lipid consequences not measured"]},{"year":2008,"claim":"Showed PKD/PKD2 mediate neurotensin-induced Hsp27 Ser-82 phosphorylation in parallel to p38, extending PKD substrate scope in cancer cells.","evidence":"siRNA of PKD/PKD2, phospho-Hsp27 blots, PKC/p38 inhibition, overexpression in PANC-1","pmids":["17570131"],"confidence":"Medium","gaps":["Direct phosphorylation versus indirect not distinguished","Single lab"]},{"year":2009,"claim":"Linked PKD activity to microtubule-dependent Golgi integrity using a Golgi-targeted activity reporter.","evidence":"Genetically encoded TGN-targeted PKD reporter, dominant-negative/siRNA, nocodazole","pmids":["19416469"],"confidence":"Medium","gaps":["Mechanistic substrate linking PKD to microtubule-driven dispersal unknown","Single lab"]},{"year":2009,"claim":"Established an inhibitory p38δ→PKD1 axis controlling insulin secretion and β-cell survival in vivo, integrating PKD into endocrine physiology.","evidence":"p38δ knockout mice, PKD1 inhibition in islets, glucose tolerance and insulin secretion assays","pmids":["19135240"],"confidence":"High","gaps":["Direct p38δ phosphorylation site on PKD1 not mapped here","PKD1 secretory substrates in β cells not identified"]},{"year":2011,"claim":"Identified Vps34 as a PKD substrate activating PI(3)P production and autophagosome formation under oxidative stress, downstream of DAPk.","evidence":"PKD-Vps34 co-IP, PI(3)P measurement, LC3 puncta assay, DAPk epistasis, autophagosome localization","pmids":["22095288"],"confidence":"High","gaps":["Vps34 phospho-site not mapped","Specificity of stress conditions not fully defined"]},{"year":2011,"claim":"Showed PKD1 promotes NF-κB and suppresses p38 in oxidative-stress survival of intestinal epithelium, defining a cytoprotective signaling output.","evidence":"siRNA, wild-type/kinase-dead overexpression, phospho-blots, NF-κB translocation","pmids":["19059215"],"confidence":"Medium","gaps":["Direct PKD1 substrate in NF-κB/p38 pathways unknown","Single lab"]},{"year":2011,"claim":"Defined PKD-Rabaptin-5 Ser407 phosphorylation as the switch directing αvβ3 integrin recycling and invasive motility, giving PKD a pro-invasive trafficking role.","evidence":"In vitro kinase assay, phospho-antibody, Rab4/Rab5 co-IP, Ser407 mutagenesis, integrin recycling and 3D invasion assays","pmids":["22975325"],"confidence":"High","gaps":["How this reconciles with PKD anti-migratory roles unclear","Upstream PKD activation in this context not fully mapped"]},{"year":2011,"claim":"Synthesized the lipid-remodeling arm of PKD trafficking—PI4KIIIβ activation, CERT/OSBP phosphorylation, and DAG→PA→LPA conversion for fission.","evidence":"Review synthesizing biochemical evidence on PI4KIIIβ and CERT/OSBP","pmids":["21421913"],"confidence":"Medium","gaps":["Review format aggregating prior data","Quantitative lipid flux at fission sites not directly resolved"]},{"year":2012,"claim":"Placed PKD upstream of a mitotic Raf–MEK1 axis controlling Golgi fragmentation and G2/M progression.","evidence":"siRNA of PKD1/2, cell cycle analysis, Raf/MEK blots, constitutively active MEK1 rescue, Golgi FRAP","pmids":["23242995"],"confidence":"High","gaps":["Direct PKD substrate connecting to Raf-1 activation unknown","Mechanism of mitotic PKD activation not defined"]},{"year":2013,"claim":"Established PRKD1 as an epigenetically silenced metastasis suppressor in breast cancer whose re-expression maintains the epithelial phenotype.","evidence":"Methylation-specific PCR, bisulfite sequencing, decitabine xenograft rescue, invasion and metastasis imaging","pmids":["23971832"],"confidence":"High","gaps":["Mechanism of EMT suppression at substrate level not defined here","Reconciliation with pro-invasive substrate phosphorylation unaddressed"]},{"year":2013,"claim":"Implicated a purinergic→PKC→PKD cascade in Schwann cell GDNF upregulation after nerve injury, extending PKD into neural injury responses.","evidence":"Pharmacological PKC/PKD inhibition, siRNA, GDNF expression assays","pmids":["23553603"],"confidence":"Medium","gaps":["Direct transcriptional mechanism unknown","Limited mechanistic detail"]},{"year":2014,"claim":"Identified the recurrent activating E710D mutation as a likely driver of polymorphous low-grade adenocarcinoma, establishing PRKD1 as a cancer oncogenic alteration.","evidence":"Tumor sequencing, functional kinase activity assay of E710D versus wild-type","pmids":["25240283"],"confidence":"Medium","gaps":["Structural basis of constitutive activation not resolved","Downstream oncogenic substrates in PLGA unknown"]},{"year":2015,"claim":"Showed PKD family kinases mediate GPCR-driven YAP inactivation via Lats2, connecting PKD to Hippo-pathway control of growth genes.","evidence":"PKD inhibitors, PKD1/2/3 triple siRNA, phospho-YAP blots, fractionation, target gene qRT-PCR","pmids":["27369082"],"confidence":"High","gaps":["Direct PKD substrate in the Lats2/YAP module not identified","Isoform-specific contributions not separated"]},{"year":2015,"claim":"Defined the GPCR→PLCγ2→PKCβ→PKD1→SSH2 axis driving neutrophil chemotaxis via cofilin/actin control.","evidence":"siRNA epistasis, PKCβ-PKD1 co-IP, in vitro SSH2 kinase assay, cofilin blots, chemotaxis assays","pmids":["25568344"],"confidence":"High","gaps":["SSH2 phospho-site not mapped here","Reconciliation with other PKD migratory roles unclear"]},{"year":2015,"claim":"Identified PRKD1 as a direct Twist1 transcriptional target required for epithelial dissemination via β-catenin and Tau phosphorylation, revealing a context-dependent pro-metastatic role.","evidence":"3D mammary organoids, Twist1 overexpression, ChIP-PCR, Prkd1 inhibition/shRNA, phosphoproteomics, in vivo tumor model","pmids":["31676574"],"confidence":"High","gaps":["Direct versus indirect β-catenin/Tau phosphorylation not fully resolved","Reconciliation with PKD1 metastasis-suppressor role context-dependent"]},{"year":2016,"claim":"Linked PKD-1 to nuclear FoxO1-HDAC7 complex formation repressing endothelial CD36 and driving proangiogenic reprogramming.","evidence":"DNA-binding assay, ChIP, FoxO1-HDAC7 co-IP, PLA, angiogenesis assays","pmids":["27013613"],"confidence":"Medium","gaps":["Direct PKD substrate in this complex unknown","Single lab"]},{"year":2018,"claim":"Defined a Rho network (GEF-H1/DLC3/PLCε) regulating PKD activation at the TGN for focal-adhesion-directed exocytosis.","evidence":"Genetically encoded PKD activity reporter, siRNA of Rho components, Rab6 carrier imaging","pmids":["30028295"],"confidence":"Medium","gaps":["How Rho input integrates with Gβγ/PLCβ3 axis unclear","Single lab"]},{"year":2021,"claim":"Identified MFF as a mitosis-specific PKD substrate driving mitochondrial fission required for chromosome segregation, extending PKD into mitotic organelle dynamics.","evidence":"In vitro kinase assay, phospho-antibody, phospho-mimetic/dead MFF mutants, chromosome segregation and checkpoint assays","pmids":["34010649"],"confidence":"High","gaps":["Mechanism restricting MFF phosphorylation to mitosis unknown","Spatial control of mitotic PKD activation undefined"]},{"year":2022,"claim":"Established the PKD→PARP12→Golgin-97 ADP-ribosylation cascade as a selective mechanism for basolateral E-cadherin carrier fission at the TGN.","evidence":"In vitro kinase and ADP-ribosylation assays, mutagenesis of multiple sites, cargo transport and carrier fission imaging","pmids":["34969853"],"confidence":"High","gaps":["PARP12 phospho-site and Golgin-97 acidic cluster generality across cargoes not fully defined","How this integrates with lipid-remodeling fission arm unclear"]},{"year":null,"claim":"How PKD1's opposing roles—epithelial-phenotype maintenance and metastasis suppression versus Twist1-driven pro-dissemination and pro-invasive integrin recycling—are reconciled within a single cell context remains unresolved.","evidence":"","pmids":[],"confidence":"Medium","gaps":["No unified model reconciling anti- and pro-metastatic PKD1 outputs","Determinants of substrate selection across contexts unknown","Spatial control of distinct PKD1 activity pools not defined"]}],"mechanism_profile":{"molecular_activity":[{"term_id":"GO:0140096","term_label":"catalytic activity, acting on a protein","supporting_discovery_ids":[0,3,16,22,30,33,34]},{"term_id":"GO:0016740","term_label":"transferase activity","supporting_discovery_ids":[0,7,16,22,33]},{"term_id":"GO:0008289","term_label":"lipid binding","supporting_discovery_ids":[6,12]},{"term_id":"GO:0008092","term_label":"cytoskeletal protein binding","supporting_discovery_ids":[15]}],"localization":[{"term_id":"GO:0005794","term_label":"Golgi apparatus","supporting_discovery_ids":[6,9,11,14,18,24,34]},{"term_id":"GO:0005829","term_label":"cytosol","supporting_discovery_ids":[4,5,9]},{"term_id":"GO:0005886","term_label":"plasma membrane","supporting_discovery_ids":[4,5,15]},{"term_id":"GO:0005634","term_label":"nucleus","supporting_discovery_ids":[31]}],"pathway":[{"term_id":"R-HSA-5653656","term_label":"Vesicle-mediated transport","supporting_discovery_ids":[6,11,14,22,34]},{"term_id":"R-HSA-162582","term_label":"Signal Transduction","supporting_discovery_ids":[1,11,29,35]},{"term_id":"R-HSA-1640170","term_label":"Cell Cycle","supporting_discovery_ids":[24,33]},{"term_id":"R-HSA-9612973","term_label":"Autophagy","supporting_discovery_ids":[20]},{"term_id":"R-HSA-1643685","term_label":"Disease","supporting_discovery_ids":[25,27,28]}],"complexes":[],"partners":["PRKCH","PRKCE","PLCB3","VPS34","RABEP5","MFF","PARP12","SSH2"],"other_free_text":[]}},"prefetch_data":{"uniprot":{"accession":"Q15139","full_name":"Serine/threonine-protein kinase D1","aliases":["Protein kinase C mu type","Protein kinase D","nPKC-D1","nPKC-mu"],"length_aa":912,"mass_kda":101.7,"function":"Serine/threonine-protein kinase that converts transient diacylglycerol (DAG) signals into prolonged physiological effects downstream of PKC, and is involved in the regulation of MAPK8/JNK1 and Ras signaling, Golgi membrane integrity and trafficking, cell survival through NF-kappa-B activation, cell migration, cell differentiation by mediating HDAC7 nuclear export, cell proliferation via MAPK1/3 (ERK1/2) signaling, and plays a role in cardiac hypertrophy, VEGFA-induced angiogenesis, genotoxic-induced apoptosis and flagellin-stimulated inflammatory response (PubMed:10764790, PubMed:12505989, PubMed:12637538, PubMed:17442957, PubMed:18509061, PubMed:19135240, PubMed:19211839). Phosphorylates the epidermal growth factor receptor (EGFR) on dual threonine residues, which leads to the suppression of epidermal growth factor (EGF)-induced MAPK8/JNK1 activation and subsequent JUN phosphorylation (PubMed:10523301). Phosphorylates RIN1, inducing RIN1 binding to 14-3-3 proteins YWHAB, YWHAE and YWHAZ and increased competition with RAF1 for binding to GTP-bound form of Ras proteins (NRAS, HRAS and KRAS). Acts downstream of the heterotrimeric G-protein beta/gamma-subunit complex to maintain the structural integrity of the Golgi membranes, and is required for protein transport along the secretory pathway. In the trans-Golgi network (TGN), regulates the fission of transport vesicles that are on their way to the plasma membrane. May act by activating the lipid kinase phosphatidylinositol 4-kinase beta (PI4KB) at the TGN for the local synthesis of phosphorylated inositol lipids, which induces a sequential production of DAG, phosphatidic acid (PA) and lyso-PA (LPA) that are necessary for membrane fission and generation of specific transport carriers to the cell surface. Under oxidative stress, is phosphorylated at Tyr-463 via SRC-ABL1 and contributes to cell survival by activating IKK complex and subsequent nuclear translocation and activation of NFKB1 (PubMed:12505989). Involved in cell migration by regulating integrin alpha-5/beta-3 recycling and promoting its recruitment in newly forming focal adhesion. In osteoblast differentiation, mediates the bone morphogenetic protein 2 (BMP2)-induced nuclear export of HDAC7, which results in the inhibition of HDAC7 transcriptional repression of RUNX2 (PubMed:18509061). In neurons, plays an important role in neuronal polarity by regulating the biogenesis of TGN-derived dendritic vesicles, and is involved in the maintenance of dendritic arborization and Golgi structure in hippocampal cells. May potentiate mitogenesis induced by the neuropeptide bombesin or vasopressin by mediating an increase in the duration of MAPK1/3 (ERK1/2) signaling, which leads to accumulation of immediate-early gene products including FOS that stimulate cell cycle progression. Plays an important role in the proliferative response induced by low calcium in keratinocytes, through sustained activation of MAPK1/3 (ERK1/2) pathway. Downstream of novel PKC signaling, plays a role in cardiac hypertrophy by phosphorylating HDAC5, which in turn triggers XPO1/CRM1-dependent nuclear export of HDAC5, MEF2A transcriptional activation and induction of downstream target genes that promote myocyte hypertrophy and pathological cardiac remodeling (PubMed:18332134). Mediates cardiac troponin I (TNNI3) phosphorylation at the PKA sites, which results in reduced myofilament calcium sensitivity, and accelerated crossbridge cycling kinetics. The PRKD1-HDAC5 pathway is also involved in angiogenesis by mediating VEGFA-induced specific subset of gene expression, cell migration, and tube formation (PubMed:19211839). In response to VEGFA, is necessary and required for HDAC7 phosphorylation which induces HDAC7 nuclear export and endothelial cell proliferation and migration. During apoptosis induced by cytarabine and other genotoxic agents, PRKD1 is cleaved by caspase-3 at Asp-378, resulting in activation of its kinase function and increased sensitivity of cells to the cytotoxic effects of genotoxic agents (PubMed:10764790). In epithelial cells, is required for transducing flagellin-stimulated inflammatory responses by binding and phosphorylating TLR5, which contributes to MAPK14/p38 activation and production of inflammatory cytokines (PubMed:17442957). Acts as an activator of NLRP3 inflammasome assembly by mediating phosphorylation of NLRP3 (By similarity). May play a role in inflammatory response by mediating activation of NF-kappa-B. May be involved in pain transmission by directly modulating TRPV1 receptor (PubMed:15471852). Plays a role in activated KRAS-mediated stabilization of ZNF304 in colorectal cancer (CRC) cells (PubMed:24623306). Regulates nuclear translocation of transcription factor TFEB in macrophages upon live S.enterica infection (By similarity)","subcellular_location":"Cytoplasm; Cell membrane; Golgi apparatus, trans-Golgi network","url":"https://www.uniprot.org/uniprotkb/Q15139/entry"},"depmap":{"release":"DepMap","has_data":true,"is_common_essential":false,"resolved_as":"","url":"https://depmap.org/portal/gene/PRKD1","classification":"Not Classified","n_dependent_lines":0,"n_total_lines":1208,"dependency_fraction":0.0},"opencell":{"profiled":false,"resolved_as":"","ensg_id":"","cell_line_id":"","localizations":[],"interactors":[{"gene":"PRKD2","stoichiometry":10.0},{"gene":"PRKD3","stoichiometry":4.0}],"url":"https://opencell.sf.czbiohub.org/search/PRKD1","total_profiled":1310},"omim":[{"mim_id":"617364","title":"CONGENITAL HEART DEFECTS AND ECTODERMAL DYSPLASIA; CHDED","url":"https://www.omim.org/entry/617364"},{"mim_id":"616912","title":"ENAH/VASP-LIKE PROTEIN; EVL","url":"https://www.omim.org/entry/616912"},{"mim_id":"613454","title":"RETT SYNDROME, CONGENITAL VARIANT","url":"https://www.omim.org/entry/613454"},{"mim_id":"609708","title":"LIPOPROTEIN LIPASE; LPL","url":"https://www.omim.org/entry/609708"},{"mim_id":"605435","title":"PROTEIN KINASE D1; PRKD1","url":"https://www.omim.org/entry/605435"}],"hpa":{"profiled":true,"resolved_as":"","reliability":"Supported","locations":[{"location":"Plasma membrane","reliability":"Supported"},{"location":"Cytosol","reliability":"Additional"}],"tissue_specificity":"Low tissue specificity","tissue_distribution":"Detected in many","driving_tissues":[],"url":"https://www.proteinatlas.org/search/PRKD1"},"hgnc":{"alias_symbol":["PKD1","PKCM","PKD","PKC-mu"],"prev_symbol":["PRKCM"]},"alphafold":{"accession":"Q15139","domains":[{"cath_id":"3.10.20.90","chopping":"49-134","consensus_level":"high","plddt":81.1874,"start":49,"end":134}],"viewer_url":"https://alphafold.ebi.ac.uk/entry/Q15139","model_url":"https://alphafold.ebi.ac.uk/files/AF-Q15139-F1-model_v6.cif","pae_url":"https://alphafold.ebi.ac.uk/files/AF-Q15139-F1-predicted_aligned_error_v6.png","plddt_mean":67.75},"mouse_models":{"mgi_url":"https://www.informatics.jax.org/marker/summary?nomen=PRKD1","jax_strain_url":"https://www.jax.org/strain/search?query=PRKD1"},"sequence":{"accession":"Q15139","fasta_url":"https://rest.uniprot.org/uniprotkb/Q15139.fasta","uniprot_url":"https://www.uniprot.org/uniprotkb/Q15139/entry","alphafold_viewer_url":"https://alphafold.ebi.ac.uk/entry/Q15139"}},"corpus_meta":[{"pmid":"11729268","id":"PMC_11729268","title":"Role of diacylglycerol in PKD recruitment to the TGN and protein transport to the plasma membrane.","date":"2001","source":"Science (New York, N.Y.)","url":"https://pubmed.ncbi.nlm.nih.gov/11729268","citation_count":350,"is_preprint":false},{"pmid":"16678913","id":"PMC_16678913","title":"PKD at the crossroads of DAG and PKC signaling.","date":"2006","source":"Trends in pharmacological sciences","url":"https://pubmed.ncbi.nlm.nih.gov/16678913","citation_count":274,"is_preprint":false},{"pmid":"19158352","id":"PMC_19158352","title":"Characterization of PKD protein-positive exosome-like vesicles.","date":"2009","source":"Journal of the American Society of Nephrology : JASN","url":"https://pubmed.ncbi.nlm.nih.gov/19158352","citation_count":274,"is_preprint":false},{"pmid":"11553327","id":"PMC_11553327","title":"The Caenorhabditis elegans autosomal dominant polycystic kidney disease gene homologs lov-1 and pkd-2 act in the same pathway.","date":"2001","source":"Current biology : CB","url":"https://pubmed.ncbi.nlm.nih.gov/11553327","citation_count":249,"is_preprint":false},{"pmid":"8947045","id":"PMC_8947045","title":"Protein kinase D (PKD) activation in intact cells through a protein kinase C-dependent signal transduction pathway.","date":"1996","source":"The EMBO journal","url":"https://pubmed.ncbi.nlm.nih.gov/8947045","citation_count":223,"is_preprint":false},{"pmid":"19135240","id":"PMC_19135240","title":"Regulation of PKD by the MAPK p38delta in insulin secretion and glucose homeostasis.","date":"2009","source":"Cell","url":"https://pubmed.ncbi.nlm.nih.gov/19135240","citation_count":208,"is_preprint":false},{"pmid":"20075061","id":"PMC_20075061","title":"Rapamycin ameliorates PKD resulting from conditional inactivation of Pkd1.","date":"2010","source":"Journal of the American Society of Nephrology : JASN","url":"https://pubmed.ncbi.nlm.nih.gov/20075061","citation_count":205,"is_preprint":false},{"pmid":"22034641","id":"PMC_22034641","title":"Mutations in multiple PKD genes may explain early and severe polycystic kidney disease.","date":"2011","source":"Journal of the American Society of Nephrology : JASN","url":"https://pubmed.ncbi.nlm.nih.gov/22034641","citation_count":179,"is_preprint":false},{"pmid":"9889186","id":"PMC_9889186","title":"The structure of a PKD domain from polycystin-1: implications for polycystic kidney disease.","date":"1999","source":"The EMBO journal","url":"https://pubmed.ncbi.nlm.nih.gov/9889186","citation_count":174,"is_preprint":false},{"pmid":"25240283","id":"PMC_25240283","title":"Hotspot activating PRKD1 somatic mutations in polymorphous low-grade adenocarcinomas of the salivary glands.","date":"2014","source":"Nature genetics","url":"https://pubmed.ncbi.nlm.nih.gov/25240283","citation_count":169,"is_preprint":false},{"pmid":"19966229","id":"PMC_19966229","title":"Chemical modifier screen identifies HDAC inhibitors as suppressors of PKD models.","date":"2009","source":"Proceedings of the National Academy of 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platelets.","date":"2002","source":"Blood","url":"https://pubmed.ncbi.nlm.nih.gov/12393506","citation_count":20,"is_preprint":false}],"cost":{"stage1":{"model":"claude-sonnet-4-6","input_tokens":47612,"output_tokens":10650,"usd":0.151293,"stage1_stop_reason":"end_turn"},"stage2":{"model":"claude-opus-4-8","input_tokens":21602,"output_tokens":8657,"usd":0.162217,"stage2_stop_reason":"end_turn"},"total_usd":0.31351,"stage1_batch_id":"msgbatch_01CNoDbkChHEkgrJnL7BwtGJ","stage2_batch_id":"msgbatch_016Y4x9E9Wg5VQDANj9quSQD","note":"batch pricing = 50% of standard"},"stage1_raw":"```json\n{\n  \"discoveries\": [\n    {\n      \"year\": 1995,\n      \"finding\": \"PKD (PRKD1) is a novel phorbol ester and diacylglycerol-stimulated serine/threonine protein kinase. A bacterially expressed NH2-terminal domain exhibited high affinity phorbol ester binding (Kd = 35 nM). The catalytic domain phosphorylates the peptide substrate syntide-2 on serine. Phorbol esters and diacylglycerol in the presence of phospholipids stimulate syntide-2 kinase activity and autophosphorylation in COS cells. Substrate specificity differs from PKC family members.\",\n      \"method\": \"In vitro kinase assay with synthetic peptide substrates, phorbol ester binding assay with bacterially expressed domain, COS-7 cell transfection and immunoprecipitation kinase assay\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Strong — reconstituted in vitro kinase assay with substrate and mutagenesis of substrate, replicated across multiple orthogonal methods in founding characterization paper\",\n      \"pmids\": [\"7836415\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 1996,\n      \"finding\": \"PKD is activated in living cells through a PKC-dependent signal transduction pathway. Phorbol esters, membrane-permeant DAG, and serum growth factors rapidly induced PKD activation. PKC inhibitors (GF I and Ro 31-8220) completely abrogated cellular PKD activation but did not inhibit PKD activity when added directly in vitro. Co-transfection with constitutively active PKCε and PKCη (but not PKCζ) strongly induced PKD activation in COS-7 cells via phosphorylation.\",\n      \"method\": \"Intact cell activation assays, immunopurified kinase activity, co-transfection with constitutively active PKC mutants, alkaline phosphatase reversal of activation, pharmacological PKC inhibition\",\n      \"journal\": \"The EMBO journal\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — multiple orthogonal methods (pharmacological inhibition, constitutively active mutants, cell-free reversal), replicated across multiple cell types\",\n      \"pmids\": [\"8947045\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 1996,\n      \"finding\": \"PKCμ (PRKD1) associates with the B cell antigen receptor (BCR) complex, co-precipitating with Syk and PLCγ1/2. BCR cross-linking activates PKCμ in a Syk-dependent and partially Btk-dependent manner. In vitro phosphorylation showed Syk and PLCγ1 are potential PKCμ substrates. PKCμ can down-regulate Syk-mediated phosphorylation of PLCγ1 in vitro, suggesting a negative feedback role.\",\n      \"method\": \"Co-immunoprecipitation from B cells, in vitro kinase assay with fusion protein substrates, DT40 B cell mutant analysis (genetic epistasis)\",\n      \"journal\": \"Immunity\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — reciprocal co-IP, in vitro kinase assay with substrates, genetic epistasis using defined mutant cell lines\",\n      \"pmids\": [\"8885868\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 1999,\n      \"finding\": \"PKD directly phosphorylates threonines T654 and T669 of the EGF receptor. PDGF (but not EGF) activates PKD in Rat-1 cells. PKD-mediated dual phosphorylation of EGFR T654/T669 suppresses EGF-induced JNK activation. An EGFR mutant (T654/669E) mimicking phosphorylation was incapable of activating JNK. Overexpression of PKD in glioblastoma cells blocked EGF- and PDGF-induced JNK activation.\",\n      \"method\": \"Site-directed mutagenesis of EGFR phosphorylation sites, overexpression of PKD, JNK activity assays, cell-type specific PKD activation assays\",\n      \"journal\": \"The EMBO journal\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Moderate — mutagenesis of substrate phosphorylation sites combined with functional readout (JNK activation), multiple cell-line validation\",\n      \"pmids\": [\"10523301\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 1999,\n      \"finding\": \"PKD/PKCμ translocates from cytosol to plasma membrane upon phorbol ester treatment in a cysteine-rich domain (CRD)-dependent manner, as visualized by GFP-PKD fusion protein in real time. A single amino acid substitution (P287G) in the second cysteine-rich motif prevented PDB-induced membrane translocation without affecting PKD kinase activation, demonstrating that PKD translocation and activation are dissociable processes.\",\n      \"method\": \"Real-time live cell imaging of GFP-PKD fusion protein, site-directed mutagenesis of CRD domain, kinase activity assay\",\n      \"journal\": \"FEBS letters\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — live imaging with functional GFP fusion, point mutagenesis dissecting translocation from activation, single lab\",\n      \"pmids\": [\"10471840\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2000,\n      \"finding\": \"PKD is present in the cytosol of quiescent B cells and mast cells and rapidly translocates to the plasma membrane upon antigen receptor triggering. Membrane redistribution requires the DAG-binding domain but is independent of catalytic activity and PH domain integrity. Membrane targeting is transient (returns to cytosol within 10 min), yet the membrane-recycled PKD remains active in the cytosol for several hours, establishing spatiotemporal dissemination of antigen receptor signals.\",\n      \"method\": \"Subcellular fractionation, kinase activity assays, domain deletion mutants, antigen receptor triggering in B cells and mast cells\",\n      \"journal\": \"The EMBO journal\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — domain deletion mutants combined with fractionation and kinase assays in primary immune cells, multiple orthogonal methods\",\n      \"pmids\": [\"10856238\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2001,\n      \"finding\": \"PKD binds diacylglycerol (DAG) and this binding is necessary for its recruitment to the trans-Golgi network (TGN). Reducing cellular DAG levels inhibited PKD recruitment and blocked protein transport from the TGN to the cell surface. PKD regulates the fission of transport carriers destined to the cell surface from the TGN.\",\n      \"method\": \"DAG manipulation (pharmacological and genetic reduction), PKD localization assay at TGN, protein transport assays to cell surface\",\n      \"journal\": \"Science\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — multiple orthogonal approaches (DAG reduction, localization, transport assay), replicated in subsequent studies\",\n      \"pmids\": [\"11729268\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2001,\n      \"finding\": \"PKCη directly phosphorylates PKD (PKCμ) activation loop serines (Ser738/742) in vitro, leading to PKD activation. PKD colocalizes with PKCη in a PH domain-dependent manner. PKCη-mediated PKD activation stimulates p42 MAPK/ERK cascade and reporter gene transcription via SRE, while simultaneously reducing PKCη-mediated JNK activation.\",\n      \"method\": \"In vitro phosphorylation assay showing PKCη phosphorylates PKD activation loop, confocal colocalization, co-expression of constitutively active PKCη, kinase substrate phosphorylation assay, reporter gene assay\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Moderate — direct in vitro phosphorylation assay identifying PKCη as writer for PKD activation loop, combined with cell-based functional readouts\",\n      \"pmids\": [\"11741879\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2001,\n      \"finding\": \"PKD is rapidly activated in intestinal epithelial cells (IEC-6, IEC-18) by phorbol esters, lysophosphatidic acid (LPA), and angiotensin II through a PKC-dependent pathway. LPA-induced PKD activation is prevented by pertussis toxin, indicating Gi coupling. PKD activation is tightly associated with autophosphorylation at serine 916. PKD does not undergo downregulation after prolonged phorbol ester treatment, unlike conventional/novel PKCs.\",\n      \"method\": \"Intact cell kinase assays, PKC inhibitor treatment, pertussis toxin treatment, autophosphorylation detection at Ser916\",\n      \"journal\": \"American journal of physiology. Cell physiology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — pharmacological dissection of pathway with multiple agonists, identification of Ser916 autophosphorylation, single lab\",\n      \"pmids\": [\"11245610\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2002,\n      \"finding\": \"Golgi localization of PKCμ (PRKD1) requires both the NH2-terminal hydrophobic region and the cysteine-rich region; deletion of either completely abrogates Golgi localization. The NH2-terminal PKCμ fragment is sufficient for Golgi membrane association. Golgi recruitment is constitutive, rapid, and independent of activation loop phosphorylation or kinase activity. A sequential activation process occurs: Golgi recruitment precedes and is required for activation loop phosphorylation (Ser738/742) by a trans-acting kinase, followed by auto- and transphosphorylation of NH2-terminal serines.\",\n      \"method\": \"Confocal microscopy of GFP-fusion deletion mutants in HeLa cells, FRAP analysis, cell fractionation, phospho-specific western blot\",\n      \"journal\": \"The Journal of cell biology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — multiple domain deletion mutants with FRAP, fractionation, and phospho-specific antibodies, multiple orthogonal methods in single rigorous study\",\n      \"pmids\": [\"11777941\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2002,\n      \"finding\": \"PKD (PKCμ) is expressed in human platelets and rapidly activated by receptors coupled to heterotrimeric G-proteins or tyrosine kinases. PKD activation in platelets is mediated downstream of PKC. Strong agonists (convulxin via GPVI, thrombin) cause sustained PKD activation; thromboxane mimetic U46619 causes transient activation. Gi-coupled receptor agonists potentiate PKD activation by submaximal PLC-coupled agonist concentrations.\",\n      \"method\": \"Platelet activation assays with multiple agonists, PKC inhibitor treatment, kinase activity measurement\",\n      \"journal\": \"Blood\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — pharmacological epistasis with multiple agonist classes in primary human cells, single lab\",\n      \"pmids\": [\"12393506\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2005,\n      \"finding\": \"PKD is activated specifically by G protein subunits β1γ2 and β3γ2 via the Golgi apparatus-associated PKCη. PKD is activated at the TGN through a Gβγ→PKCη→PKD axis. Compromising PKCη kinase activity inhibits protein transport from TGN to cell surface. Constitutively active PKCη caused Golgi fragmentation that was inhibited by kinase-inactive PKD, placing PKD downstream of PKCη in the vesicle-generating pathway.\",\n      \"method\": \"Dominant-negative and constitutively active kinase constructs, Golgi fragmentation assay, protein transport assay, epistasis by kinase-dead PKD\",\n      \"journal\": \"The Journal of cell biology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — epistatic ordering of Gβγ→PKCη→PKD with multiple dominant-negative and constitutively active constructs, replicated in subsequent work\",\n      \"pmids\": [\"15824133\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2006,\n      \"finding\": \"The C1b domain of PKD isoforms binds phorbol esters with high affinity, while the C1a domain has non-consensus residues that mainly contribute to structural fold rather than ligand binding. C1a and C1b in intact C1a-C1b of PKD1 show opposite selectivity for phorbol esters (PDBu) and DAG (DOG). A conserved lysine at position 22 in C1b accounts for weaker DAG affinity. Mutation of C1a in full-length PKD3-GFP reduces DOG-induced plasma membrane translocation but not PMA-induced translocation.\",\n      \"method\": \"Radioligand binding assay with [3H]PDBu, site-directed mutagenesis of C1 domain residues, GFP-PKD translocation assay in living cells\",\n      \"journal\": \"The Biochemical journal\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Moderate — in vitro binding assays with mutagenesis combined with live cell translocation imaging, multiple orthogonal methods\",\n      \"pmids\": [\"18076381\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2007,\n      \"finding\": \"PLCβ3 is the specific phospholipase C isoform required for PKD1 activation at the TGN. Gβγ-dependent Golgi fragmentation, PKD1 activation loop phosphorylation, and TGN-to-plasma membrane transport were inhibited by a PI-PLC inhibitor (U73122) and by siRNA knockdown of PLCβ3 (but not other PI-PLC isoforms). A PI-PLC activator (m-3M3FBS) induced Golgi vesiculation and PKD1 activation loop phosphorylation. PLCβ3 acts upstream of PKCη and PKD in the vesicle-generating pathway by producing DAG.\",\n      \"method\": \"siRNA knockdown of individual PLCβ isoforms, pharmacological PI-PLC inhibition and activation, PKD1 activation loop phosphorylation western blot, TGN-to-plasma membrane transport assay\",\n      \"journal\": \"The Biochemical journal\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — siRNA isoform-selective knockdown combined with pharmacological modulation and functional transport assay, multiple orthogonal methods\",\n      \"pmids\": [\"17492941\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2007,\n      \"finding\": \"PKD depletion by siRNA inhibits TGN-to-cell surface trafficking, while expression of constitutively active PKD converts TGN into small vesicles. PKD is required for membrane fission to generate transport carriers, and this activity controls the size of transport carriers and prevents uncontrolled vesiculation of TGN. PKD functions as a dimer at the TGN for membrane fission.\",\n      \"method\": \"siRNA depletion of PKD, constitutively active PKD expression, electron microscopy and fluorescence microscopy of Golgi morphology, protein transport assays\",\n      \"journal\": \"The Journal of cell biology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — loss-of-function (siRNA) and gain-of-function (constitutively active) with morphological readout, replicated across studies\",\n      \"pmids\": [\"18086912\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2007,\n      \"finding\": \"PKD is recruited to the leading edge of migrating cells where it co-localizes with F-actin, Arp3, and cortactin. PDGF activates PKD and recruits it to the leading edge. PKD directly interacts with F-actin and phosphorylates cortactin in vitro. Dominant-negative PKD or PKD siRNA enhanced cell migration, while wild-type PKD overexpression reduced migration, establishing a negative regulatory function of PKD in cell migration.\",\n      \"method\": \"Confocal co-localization, in vitro pulldown with F-actin, in vitro kinase assay for cortactin phosphorylation, dominant-negative overexpression, siRNA knockdown, migration assay\",\n      \"journal\": \"FEBS letters\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Moderate — in vitro kinase assay identifying cortactin as substrate combined with loss-of-function (siRNA, dominant-negative) migration phenotype and F-actin interaction\",\n      \"pmids\": [\"17707375\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2008,\n      \"finding\": \"PKD phosphorylates type IIα PIP kinase on activation loop threonine T376, inhibiting enzyme activity. A phospho-specific antibody confirmed T376 phosphorylation in living cells, enhanced when PKD was activated. Mutation of T376 to aspartate (phosphomimetic) significantly inhibited PIP kinase activity. PKD was identified as the responsible kinase by pharmacological studies and in vitro confirmation.\",\n      \"method\": \"In vitro phosphorylation assay, phospho-specific antibody, site-directed mutagenesis of T376, pharmacological PKD inhibition in cells\",\n      \"journal\": \"Cellular signalling\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Moderate — in vitro kinase assay identifying T376 as PKD phosphorylation site, mutagenesis confirming functional effect, phospho-specific antibody validation in cells\",\n      \"pmids\": [\"16563698\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2008,\n      \"finding\": \"PKD and PKD2 mediate neurotensin-induced phosphorylation of Hsp27 at Ser-82 in PANC-1 pancreatic cancer cells through a PKC-dependent pathway. siRNA knockdown of PKD or PKD2 individually reduced Hsp27 Ser-82 phosphorylation; combined knockdown of both virtually abolished it. This pathway operates in parallel to p38 MAPK-mediated Hsp27 phosphorylation.\",\n      \"method\": \"siRNA knockdown of PKD and PKD2, phospho-specific western blot for Hsp27 Ser-82, pharmacological inhibition of PKC and p38 MAPK, PKD overexpression in stably transfected cells\",\n      \"journal\": \"Journal of cellular biochemistry\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — siRNA knockdown of two isoforms combined with pharmacological dissection and overexpression, single lab\",\n      \"pmids\": [\"17570131\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2009,\n      \"finding\": \"A Golgi-targeted PKD activity reporter (PKD-specific substrate fused to EGFP targeted to TGN via p230 GRIP domain) revealed that nocodazole-induced Golgi dispersal is associated with local PKD activation. Dominant-negative PKD or PKD siRNA depletion blocked nocodazole-induced Golgi break-up, identifying a link between PKD activity and microtubule cytoskeleton in regulating Golgi complex integrity.\",\n      \"method\": \"Genetically encoded Golgi-targeted PKD activity reporter, phospho-specific antibody validation, ratiometric fluorescence imaging, dominant-negative PKD expression, siRNA knockdown, nocodazole treatment\",\n      \"journal\": \"Traffic\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — validated molecular reporter with loss-of-function confirmation, single lab\",\n      \"pmids\": [\"19416469\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2009,\n      \"finding\": \"p38δ MAPK catalyzes an inhibitory phosphorylation of PKD1, thereby attenuating stimulated insulin secretion from pancreatic β cells. Deletion of p38δ results in pronounced PKD activation and enhanced insulin exocytosis. Inhibition of PKD1 reverses enhanced insulin secretion in p38δ-deficient islets. The p38δ-PKD1 pathway integrates regulation of insulin secretory capacity and β cell survival.\",\n      \"method\": \"p38δ knockout mice, PKD1 inhibition in isolated islets, glucose tolerance tests, in vivo and ex vivo insulin secretion measurements, genetic epistasis (p38δ KO + PKD1 inhibition)\",\n      \"journal\": \"Cell\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — genetic knockout combined with pharmacological rescue, epistatic ordering of p38δ→PKD1 in insulin secretion, published in high-impact journal with multiple orthogonal approaches\",\n      \"pmids\": [\"19135240\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2011,\n      \"finding\": \"PKD phosphorylates Vps34 (a lipid kinase), leading to Vps34 activation, PI(3)P formation, and autophagosome formation in response to oxidative stress. PKD is found in the same molecular complex with Vps34 by co-immunoprecipitation. PKD is activated by DAPk (death-associated protein kinase) upstream in this cascade. PKD is recruited to LC3-positive autophagosomal membranes.\",\n      \"method\": \"Co-immunoprecipitation of PKD-Vps34 complex, PI(3)P measurement, autophagosome formation assay (LC3 puncta), epistasis with DAPk, PKD localization to autophagosomes\",\n      \"journal\": \"Cell death and differentiation\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — co-IP identifying complex, functional PI(3)P production assay, autophagosome localization, epistatic ordering of DAPk→PKD→Vps34\",\n      \"pmids\": [\"22095288\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2011,\n      \"finding\": \"PKD1 promotes NF-κB activation and suppresses p38 MAPK in response to H2O2 in intestinal epithelial cells, thereby protecting against apoptosis. PKD1 siRNA inhibited H2O2-induced NF-κB activation, p65 translocation, and IκBα phosphorylation. Wild-type PKD1 overexpression reduced p38 MAPK and MKK3/6 phosphorylation, while kinase-dead PKD1 increased it. PKD1 does not affect ERK1/2 or JNK phosphorylation.\",\n      \"method\": \"siRNA knockdown, overexpression of wild-type and kinase-dead PKD1, phospho-specific western blots for NF-κB pathway components and MAPKs, NF-κB translocation assay\",\n      \"journal\": \"Biochemical and biophysical research communications\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — loss-of-function (siRNA) and gain-of-function with kinase-dead control, single lab, multiple pathway readouts\",\n      \"pmids\": [\"19059215\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2011,\n      \"finding\": \"PKD mediates PDGF-dependent αvβ3 integrin recycling through phosphorylation of Rabaptin-5 at Ser407. PKD phosphorylation of Rabaptin-5 Ser407 is necessary and sufficient for PDGF-dependent short-loop αvβ3 recycling and inhibition of α5β1 recycling. Rab4 (not Rab5) interacts with phosphorylated Rabaptin-5 at the leading edge to promote αvβ3 delivery, driving persistent cell motility and invasion.\",\n      \"method\": \"In vitro kinase assay identifying Rabaptin-5 Ser407 as PKD substrate, phospho-specific antibody, Rab4/Rab5 co-immunoprecipitation with phospho-Rabaptin-5, mutagenesis of Ser407, integrin recycling assay, 2D migration and 3D invasion assay\",\n      \"journal\": \"Developmental cell\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Moderate — in vitro kinase assay with substrate identification, phospho-specific antibody validation, Ser407 mutagenesis with functional rescue, integrin trafficking readout\",\n      \"pmids\": [\"22975325\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2011,\n      \"finding\": \"PKD activates PI4KIIIβ (phosphatidylinositol 4-kinase IIIβ) at the TGN to promote PI4P production. PI4P then recruits OSBP and CERT which control sphingolipid and sterol levels. PKD subsequently phosphorylates OSBP and CERT to dissociate them from TGN. This drives sequential DAG→PA→LPA lipid conversion necessary for membrane fission to generate cell surface transport carriers.\",\n      \"method\": \"Review synthesizing biochemical evidence from preceding studies; includes lipid kinase activation and substrate phosphorylation evidence\",\n      \"journal\": \"Cold Spring Harbor perspectives in biology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — mechanistic synthesis of established biochemical data on PI4KIIIβ activation and CERT/OSBP phosphorylation by PKD, review format but citing primary experiments\",\n      \"pmids\": [\"21421913\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2012,\n      \"finding\": \"PKD controls mitotic Golgi fragmentation via a Raf-MEK1 pathway. siRNA depletion of PKD1 and PKD2 causes G2 cell cycle arrest and prevents mitosis entry. PKD inhibition blocks mitotic Raf-1 and MEK activation, and consequently mitotic Golgi fragmentation; expression of active MEK1 rescues the PKD-depleted phenotype. FRAP analysis showed PKD is crucial for cleavage of non-compact Golgi membrane zones in G2 phase.\",\n      \"method\": \"siRNA depletion of PKD1/PKD2, cell cycle analysis, Raf/MEK activation western blot, constitutively active MEK1 rescue, Golgi FRAP analysis\",\n      \"journal\": \"Molecular biology of the cell\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — epistatic rescue of MEK1 expression downstream of PKD depletion, combined with FRAP and cell cycle analysis, multiple orthogonal methods\",\n      \"pmids\": [\"23242995\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2013,\n      \"finding\": \"PRKD1 promoter is aberrantly methylated and silenced in invasive breast cancer cells. Re-expression of PKD1 via decitabine (DNA methyltransferase inhibitor) restores PKD1 expression and blocks tumor metastasis to the lung in a xenograft model in a PKD1-dependent manner. PKD1 expression maintains the epithelial phenotype by preventing EMT in normal mammary gland cells.\",\n      \"method\": \"Methylation-specific PCR, bisulfite deep sequencing, decitabine treatment in vitro and in vivo xenograft model, transwell invasion assay, in vivo bioluminescence imaging of metastasis\",\n      \"journal\": \"Breast cancer research\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — in vivo xenograft rescue experiment with PKD1-dependent metastasis suppression, combined with multiple methylation detection methods\",\n      \"pmids\": [\"23971832\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2013,\n      \"finding\": \"Nerve injury-induced GDNF upregulation in Schwann cells is mediated by a purinergic receptor→PKC→PKD signaling cascade. Activation of Schwann cell purinergic receptors leads to PKC activation, which activates PKD, which drives increased GDNF transcription.\",\n      \"method\": \"Pharmacological inhibition of PKC and PKD, siRNA knockdown, GDNF expression assays in Schwann cells following nerve injury model\",\n      \"journal\": \"Glia\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Weak — pharmacological and siRNA-based pathway dissection, single lab, limited mechanistic detail in abstract\",\n      \"pmids\": [\"23553603\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2014,\n      \"finding\": \"PRKD1 hotspot somatic mutation E710D (p.Glu710Asp) is a kinase-activating alteration found in 72.9% of polymorphous low-grade adenocarcinomas (PLGAs) of salivary glands but not in other salivary gland tumors. Functional studies demonstrated this mutation constitutively activates PRKD1 kinase activity, likely acting as a driver of PLGA.\",\n      \"method\": \"Tumor sequencing, functional characterization of kinase activity of E710D mutant vs wild-type\",\n      \"journal\": \"Nature genetics\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — functional kinase activity assay confirming activating nature of mutation, large tumor cohort, but limited mechanistic detail in abstract\",\n      \"pmids\": [\"25240283\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2015,\n      \"finding\": \"PRKD1 is a direct transcriptional target of Twist1 and is not expressed in normal mammary epithelium. Prkd1 is required for Twist1-induced epithelial dissemination: pharmacological and genetic Prkd1 inhibition blocks ECM-directed protrusions, epithelial release, and migration through ECM. Prkd1 induces phosphorylation of β-catenin (inactivating) and Tau (microtubule-depolymerizing) as part of its dissemination program. Prkd1 knockdown in vivo blocked primary tumor invasion and distant metastasis.\",\n      \"method\": \"3D mammary organoid culture model, Twist1 overexpression, Prkd1 pharmacological inhibition and shRNA knockdown, ChIP-PCR confirming direct Twist1 binding to Prkd1 promoter, antibody-based phosphoproteomics, in vivo mouse tumor model\",\n      \"journal\": \"Cancer research\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — ChIP-PCR confirming direct transcriptional target, loss-of-function rescue in 3D and in vivo, phosphoproteomic substrate identification, multiple orthogonal methods\",\n      \"pmids\": [\"31676574\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2015,\n      \"finding\": \"GPCR activation induces biphasic YAP regulation in intestinal epithelial cells through PKD family kinases. PKD family inhibitors or siRNA-mediated knockdown of PKD1/PKD2/PKD3 prevented YAP phosphorylation at Ser127 and Ser397 via Lats2, cytoplasmic accumulation of YAP, and induction of YAP/TEAD-regulated genes (CTGF and Areg) in response to angiotensin II, vasopressin, or serum.\",\n      \"method\": \"PKD family inhibitors (CRT0066101, kb NB 142-70), siRNA knockdown of PKD1/2/3, phospho-specific western blot for YAP, nuclear-cytoplasmic fractionation, qRT-PCR of YAP target genes\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — both pharmacological and genetic (siRNA triple knockdown) loss-of-function with multiple pathway readouts, single lab\",\n      \"pmids\": [\"27369082\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2015,\n      \"finding\": \"PKD1 promotes neutrophil chemotaxis through the GPCR→PLCγ2(PI3K-dependent)→PKCβ→PKD1→SSH2 signaling axis. PKCβ specifically interacts with PKD1 and is required for chemotaxis. PKD1 phosphorylates slingshot phosphatase 2 (SSH2), which regulates cofilin phosphorylation and actin cytoskeletal reorganization.\",\n      \"method\": \"siRNA knockdown of pathway components, co-immunoprecipitation of PKCβ-PKD1 interaction, in vitro kinase assay for SSH2 phosphorylation, cofilin phosphorylation western blot, chemotaxis assay\",\n      \"journal\": \"Molecular biology of the cell\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Moderate — in vitro kinase assay identifying SSH2 as PKD1 substrate, co-IP of PKCβ-PKD1 interaction, siRNA epistasis in neutrophil chemotaxis\",\n      \"pmids\": [\"25568344\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2016,\n      \"finding\": \"LPA-mediated CD36 transcriptional repression by PKD-1 involves PKD-1 signaling-mediated formation of a FoxO1-HDAC7 complex in the nucleus. PKD-1 promotes nuclear accumulation of HDAC7, where it interacts with FoxO1 to suppress endothelial CD36 transcription, leading to proangiogenic reprogramming including ephrin B2 expression.\",\n      \"method\": \"Avidin-biotin-conjugated DNA-binding assay, chromatin immunoprecipitation, co-immunoprecipitation of FoxO1-HDAC7 complex, proximal ligation assay, immunofluorescence, gene transfection, spheroid angiogenesis assay, in vivo Matrigel angiogenesis\",\n      \"journal\": \"Arteriosclerosis, thrombosis, and vascular biology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — co-IP, ChIP, and DNA-binding assay identifying nuclear FoxO1-HDAC7 complex downstream of PKD-1, single lab with multiple methods\",\n      \"pmids\": [\"27013613\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2018,\n      \"finding\": \"A Rho signaling network comprising GEF-H1, the RhoGAP DLC3, and the Rho effector PLCε regulates PKD activation at trans-Golgi membranes. This molecular network coordinates formation of TGN-derived Rab6-positive transport carriers for localized exocytosis at focal adhesions.\",\n      \"method\": \"Genetically encoded PKD activity reporter (G-PKDrep), siRNA knockdown of Rho pathway components (GEF-H1, DLC3, PLCε), live cell imaging of Rab6 transport carriers, focal adhesion exocytosis assay\",\n      \"journal\": \"eLife\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — validated molecular reporter for PKD activity combined with siRNA epistasis, single lab\",\n      \"pmids\": [\"30028295\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2021,\n      \"finding\": \"PKD directly phosphorylates the mitochondrial fission factor MFF specifically during mitosis. PKD-dependent MFF phosphorylation is required and sufficient for mitochondrial fission in mitotic (but not interphase) cells. Phosphorylation of MFF by PKD is crucial for chromosome segregation and promotes cell survival by inhibiting adaptation of the mitotic checkpoint.\",\n      \"method\": \"In vitro kinase assay identifying MFF as PKD substrate during mitosis, phospho-specific antibody, expression of phospho-mimetic and phospho-dead MFF mutants, chromosome segregation assay, mitotic checkpoint analysis\",\n      \"journal\": \"Cell reports\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Moderate — in vitro kinase assay identifying MFF as PKD substrate, mutagenesis of phosphorylation site with functional readout for mitosis and chromosome segregation\",\n      \"pmids\": [\"34010649\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2022,\n      \"finding\": \"PKD directly phosphorylates PARP12 at the TGN, which is essential to stimulate PARP12 catalytic activity. Activated PARP12 then mono-ADP-ribosylates Golgin-97 at an acidic cluster in its coiled-coil domain, which is required for E-cadherin and VSVG carrier fission and transport from TGN to plasma membrane. PARP12/Golgin-97 ADP-ribosylation is selective for Golgin-97-dependent (not Golgin-245-dependent) basolateral cargo transport.\",\n      \"method\": \"In vitro kinase assay showing PKD phosphorylates PARP12, in vitro ADP-ribosylation assay of Golgin-97 by PARP12, mutagenesis of Golgin-97 acidic cluster and PARP12 phosphorylation site, cargo transport assay (E-cadherin, VSVG), live imaging of carrier fission\",\n      \"journal\": \"Proceedings of the National Academy of Sciences\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Moderate — in vitro kinase assay and in vitro ADP-ribosylation assay with mutagenesis of multiple functional sites, combined with cargo transport readout; multiple orthogonal methods in single study\",\n      \"pmids\": [\"34969853\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2011,\n      \"finding\": \"Gαq, but not the closely related Gα11, promotes PKD autophosphorylation at Ser748 (activation loop) in a PKC-independent manner. Gα11, Gα14, and Gα15 mediate PKD activation in a PKC-dependent manner. Gαq-specific PKC-independent PKD activation was also demonstrated using Pasteurella multocida toxin (selective Gαq activator) in Swiss 3T3 cells.\",\n      \"method\": \"COS-7 cell co-transfection with Gq-family Gα subunits, AlF4⁻ activation, PKC inhibitor (GF1) treatment, phospho-specific western blot for Ser744 (PKC transphosphorylation) and Ser748 (autophosphorylation), in vitro kinase assay\",\n      \"journal\": \"Cellular signalling\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — pharmacological dissection combined with Gα subunit specificity analysis and phospho-site specific readouts, single lab\",\n      \"pmids\": [\"22227248\"],\n      \"is_preprint\": false\n    }\n  ],\n  \"current_model\": \"PRKD1 (PKD1/PKCμ) is a DAG- and phorbol ester-activated serine/threonine kinase that is recruited to the trans-Golgi network via DAG binding, where it is sequentially activated by a Gβγ→PLCβ3→PKCη→PKD transphosphorylation cascade and then drives membrane fission to generate basolateral transport carriers through activation of PI4KIIIβ, phosphorylation of CERT/OSBP, and sequential DAG→PA→LPA lipid remodeling; at the TGN PKD also directly phosphorylates PARP12 to catalyze Golgin-97 ADP-ribosylation required for E-cadherin transport, and controls mitotic Golgi fragmentation via a Raf-MEK1 axis; in the cytoplasm it acts downstream of PKC (particularly PKCε/η) to relay GPCR and antigen receptor signals, phosphorylates substrates including the EGFR (T654/T669), Hsp27 (via p38δ-inhibited activation in β cells to regulate insulin secretion), Vps34 (promoting autophagy under oxidative stress), Rabaptin-5 (Ser407, directing αvβ3 integrin recycling and invasive migration), cortactin (negatively regulating actin-based cell migration), MFF (driving mitotic mitochondrial fission essential for chromosome segregation), type IIα PIP kinase (T376, inhibitory), and SSH2 (regulating cofilin and neutrophil chemotaxis); its expression is epigenetically silenced by promoter methylation in invasive breast cancer, and its re-expression suppresses EMT and metastasis while its Twist1-driven induction in cancer promotes epithelial dissemination through β-catenin and Tau phosphorylation.\"\n}\n```","stage2_raw":"{\n  \"mechanistic_narrative\": \"PRKD1 (PKD/PKCμ) is a diacylglycerol- and phorbol ester-activated serine/threonine kinase that couples lipid second-messenger signaling to membrane trafficking, cytoskeletal dynamics, and cell-fate decisions [#0, #6]. It is activated in cells through a PKC-dependent relay in which novel PKC isoforms (PKCε/η) transphosphorylate the PKD activation loop (Ser738/742), a step distinct from and downstream of its DAG-driven membrane recruitment [#1, #4, #7]; activation can also proceed through Gq-family and Gβγ-coupled GPCR inputs [#11, #35]. At the trans-Golgi network, DAG binding recruits PKD where a Gβγ→PLCβ3→PKCη→PKD cascade activates it to drive fission of basolateral transport carriers, acting through PI4KIIIβ activation and CERT/OSBP phosphorylation and through direct phosphorylation of PARP12 that licenses Golgin-97 ADP-ribosylation for E-cadherin transport [#11, #13, #14, #23, #34]. PKD additionally governs Golgi integrity during the cell cycle via a Raf–MEK1 axis and drives mitotic mitochondrial fission by phosphorylating MFF, a step required for faithful chromosome segregation [#24, #33]. In the cytoplasm PKD relays GPCR and antigen-receptor signals and phosphorylates a diverse substrate set—EGFR T654/T669 to suppress JNK signaling, Rabaptin-5 Ser407 to direct αvβ3 integrin recycling and invasion, cortactin and SSH2 to control actin-based migration and chemotaxis, and Vps34 to promote autophagy under oxidative stress [#3, #15, #16, #20, #22, #30]. PRKD1 is epigenetically silenced by promoter methylation in invasive breast cancer where it maintains the epithelial phenotype and suppresses metastasis, yet as a direct Twist1 transcriptional target it can also drive epithelial dissemination through β-catenin and Tau phosphorylation; a recurrent activating E710D mutation marks polymorphous low-grade adenocarcinoma of the salivary gland [#25, #27, #28].\",\n  \"teleology\": [\n    {\n      \"year\": 1995,\n      \"claim\": \"Established PRKD1 as a distinct DAG/phorbol ester-responsive serine/threonine kinase rather than a conventional PKC, defining its founding biochemical identity.\",\n      \"evidence\": \"In vitro kinase assays with syntide-2, phorbol ester binding by bacterially expressed N-terminal domain, COS cell autophosphorylation\",\n      \"pmids\": [\"7836415\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Physiological substrates not yet identified\", \"Cellular activation pathway not yet defined\"]\n    },\n    {\n      \"year\": 1996,\n      \"claim\": \"Showed PKD activation in cells is PKC-dependent, placing it downstream of novel PKC isoforms and resolving how DAG signals reach the kinase.\",\n      \"evidence\": \"Pharmacological PKC inhibition, constitutively active PKCε/η co-transfection, cell-free reversal in COS-7 cells\",\n      \"pmids\": [\"8947045\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Direct phosphorylation site on PKD not yet mapped\", \"Identity of the upstream kinase at endogenous sites unconfirmed in 1996\"]\n    },\n    {\n      \"year\": 1996,\n      \"claim\": \"Linked PKD to antigen receptor signaling by showing it associates with and modulates the BCR/Syk/PLCγ module, extending its role into immune-receptor relays.\",\n      \"evidence\": \"Co-IP from B cells, in vitro kinase assays on Syk/PLCγ1, DT40 genetic epistasis\",\n      \"pmids\": [\"8885868\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"In vivo relevance of Syk/PLCγ1 phosphorylation not established\", \"Whether feedback role is physiologically dominant unknown\"]\n    },\n    {\n      \"year\": 1999,\n      \"claim\": \"Identified EGFR T654/T669 as direct PKD substrates whose phosphorylation suppresses JNK signaling, giving PKD a defined receptor-modulatory output.\",\n      \"evidence\": \"EGFR site mutagenesis, PKD overexpression, JNK activity assays in Rat-1 and glioblastoma cells\",\n      \"pmids\": [\"10523301\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Endogenous stoichiometry of EGFR phosphorylation unknown\", \"Direct in vitro demonstration limited\"]\n    },\n    {\n      \"year\": 1999,\n      \"claim\": \"Dissected PKD membrane translocation from kinase activation, establishing the CRD as the targeting module independent of catalytic activity.\",\n      \"evidence\": \"Real-time GFP-PKD imaging, P287G CRD mutant, kinase assays\",\n      \"pmids\": [\"10471840\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Lipid ligand specificity of each C1 subdomain not resolved here\", \"Subcellular target of translocation beyond plasma membrane not addressed\"]\n    },\n    {\n      \"year\": 2000,\n      \"claim\": \"Demonstrated transient receptor-triggered membrane targeting followed by sustained cytosolic activity, defining how PKD spatiotemporally disseminates antigen-receptor signals.\",\n      \"evidence\": \"Subcellular fractionation, domain deletion mutants, kinase assays in B cells and mast cells\",\n      \"pmids\": [\"10856238\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Cytosolic substrates of recycled active PKD not identified\", \"Mechanism sustaining cytosolic activity unclear\"]\n    },\n    {\n      \"year\": 2001,\n      \"claim\": \"Defined PKD as a regulator of TGN-to-surface trafficking, recruited by DAG and required for fission of transport carriers.\",\n      \"evidence\": \"DAG manipulation, TGN localization, protein transport assays\",\n      \"pmids\": [\"11729268\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Direct fission substrates not yet identified\", \"Carrier cargo selectivity not addressed\"]\n    },\n    {\n      \"year\": 2001,\n      \"claim\": \"Mapped PKCη as the direct activation-loop kinase (Ser738/742) for PKD, completing the upstream PKC→PKD writer relationship and linking it to ERK/SRE signaling.\",\n      \"evidence\": \"In vitro phosphorylation, confocal colocalization, constitutively active PKCη, reporter assays\",\n      \"pmids\": [\"11741879\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Whether PKCη is the sole physiological activation-loop kinase unknown\", \"Context-specificity versus PKCε not resolved\"]\n    },\n    {\n      \"year\": 2001,\n      \"claim\": \"Resolved the Golgi recruitment logic—dual N-terminal hydrophobic plus CRD requirement, constitutive and activation-independent—and ordered recruitment before activation-loop phosphorylation.\",\n      \"evidence\": \"GFP-fusion deletion mutants, FRAP, fractionation, phospho-specific blots in HeLa\",\n      \"pmids\": [\"11777941\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Identity of the trans-acting Golgi activation-loop kinase not established here\", \"Lipid versus protein contributions to Golgi anchoring unresolved\"]\n    },\n    {\n      \"year\": 2001,\n      \"claim\": \"Extended PKD activation to GPCR/Gi-coupled inputs (LPA, angiotensin II) in epithelial cells and identified Ser916 autophosphorylation as an activity marker.\",\n      \"evidence\": \"Intact-cell kinase assays, pertussis toxin, Ser916 autophosphorylation detection in IEC cells\",\n      \"pmids\": [\"11245610\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Single lab\", \"Downstream effectors of LPA/AngII-induced PKD not identified\"]\n    },\n    {\n      \"year\": 2002,\n      \"claim\": \"Showed PKD is activated downstream of PKC in platelets by GPCR and tyrosine kinase agonists, broadening its receptor-relay role to hemostatic cells.\",\n      \"evidence\": \"Platelet agonist activation assays, PKC inhibition, kinase activity measurement\",\n      \"pmids\": [\"12393506\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Functional platelet substrates of PKD not identified\", \"Single lab\"]\n    },\n    {\n      \"year\": 2005,\n      \"claim\": \"Established the Gβγ→PKCη→PKD axis at the TGN with epistatic ordering, defining the heterotrimeric G-protein input to Golgi carrier formation.\",\n      \"evidence\": \"Dominant-negative/constitutively active constructs, Golgi fragmentation and transport assays, kinase-dead PKD epistasis\",\n      \"pmids\": [\"15824133\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Source of Gβγ at the Golgi not defined\", \"Link to PLC isoform not yet identified at this step\"]\n    },\n    {\n      \"year\": 2007,\n      \"claim\": \"Identified PLCβ3 as the specific DAG-generating PLC upstream of PKCη/PKD at the TGN, completing the lipid-signaling input to carrier fission.\",\n      \"evidence\": \"Isoform-selective siRNA, PI-PLC inhibitor/activator, activation-loop phospho-blot, transport assays\",\n      \"pmids\": [\"17492941\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"How PLCβ3 is recruited/activated at the Golgi unclear\", \"Spatial coupling to Gβγ not directly imaged\"]\n    },\n    {\n      \"year\": 2007,\n      \"claim\": \"Defined PKD's mechanistic role as a dimeric membrane-fission machine controlling carrier size and preventing uncontrolled TGN vesiculation.\",\n      \"evidence\": \"siRNA depletion, constitutively active PKD, EM and fluorescence Golgi morphology, transport assays\",\n      \"pmids\": [\"18086912\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Direct fission-effector substrates not identified in this study\", \"Structural basis of dimeric fission unknown\"]\n    },\n    {\n      \"year\": 2007,\n      \"claim\": \"Established PKD as a negative regulator of cell migration acting through cortactin phosphorylation at the leading edge.\",\n      \"evidence\": \"Confocal colocalization, F-actin pulldown, in vitro cortactin kinase assay, dominant-negative/siRNA migration assays\",\n      \"pmids\": [\"17707375\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Cortactin phospho-site functional consequence on actin not fully mapped\", \"Reconciliation with pro-invasive roles unclear\"]\n    },\n    {\n      \"year\": 2008,\n      \"claim\": \"Identified type IIα PIP kinase T376 as an inhibitory PKD substrate, linking PKD to phosphoinositide pool regulation.\",\n      \"evidence\": \"In vitro kinase assay, phospho-specific antibody, T376 mutagenesis, pharmacological PKD inhibition\",\n      \"pmids\": [\"16563698\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Physiological context of PIP kinase inhibition not defined\", \"Downstream lipid consequences not measured\"]\n    },\n    {\n      \"year\": 2008,\n      \"claim\": \"Showed PKD/PKD2 mediate neurotensin-induced Hsp27 Ser-82 phosphorylation in parallel to p38, extending PKD substrate scope in cancer cells.\",\n      \"evidence\": \"siRNA of PKD/PKD2, phospho-Hsp27 blots, PKC/p38 inhibition, overexpression in PANC-1\",\n      \"pmids\": [\"17570131\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Direct phosphorylation versus indirect not distinguished\", \"Single lab\"]\n    },\n    {\n      \"year\": 2009,\n      \"claim\": \"Linked PKD activity to microtubule-dependent Golgi integrity using a Golgi-targeted activity reporter.\",\n      \"evidence\": \"Genetically encoded TGN-targeted PKD reporter, dominant-negative/siRNA, nocodazole\",\n      \"pmids\": [\"19416469\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Mechanistic substrate linking PKD to microtubule-driven dispersal unknown\", \"Single lab\"]\n    },\n    {\n      \"year\": 2009,\n      \"claim\": \"Established an inhibitory p38δ→PKD1 axis controlling insulin secretion and β-cell survival in vivo, integrating PKD into endocrine physiology.\",\n      \"evidence\": \"p38δ knockout mice, PKD1 inhibition in islets, glucose tolerance and insulin secretion assays\",\n      \"pmids\": [\"19135240\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Direct p38δ phosphorylation site on PKD1 not mapped here\", \"PKD1 secretory substrates in β cells not identified\"]\n    },\n    {\n      \"year\": 2011,\n      \"claim\": \"Identified Vps34 as a PKD substrate activating PI(3)P production and autophagosome formation under oxidative stress, downstream of DAPk.\",\n      \"evidence\": \"PKD-Vps34 co-IP, PI(3)P measurement, LC3 puncta assay, DAPk epistasis, autophagosome localization\",\n      \"pmids\": [\"22095288\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Vps34 phospho-site not mapped\", \"Specificity of stress conditions not fully defined\"]\n    },\n    {\n      \"year\": 2011,\n      \"claim\": \"Showed PKD1 promotes NF-κB and suppresses p38 in oxidative-stress survival of intestinal epithelium, defining a cytoprotective signaling output.\",\n      \"evidence\": \"siRNA, wild-type/kinase-dead overexpression, phospho-blots, NF-κB translocation\",\n      \"pmids\": [\"19059215\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Direct PKD1 substrate in NF-κB/p38 pathways unknown\", \"Single lab\"]\n    },\n    {\n      \"year\": 2011,\n      \"claim\": \"Defined PKD-Rabaptin-5 Ser407 phosphorylation as the switch directing αvβ3 integrin recycling and invasive motility, giving PKD a pro-invasive trafficking role.\",\n      \"evidence\": \"In vitro kinase assay, phospho-antibody, Rab4/Rab5 co-IP, Ser407 mutagenesis, integrin recycling and 3D invasion assays\",\n      \"pmids\": [\"22975325\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"How this reconciles with PKD anti-migratory roles unclear\", \"Upstream PKD activation in this context not fully mapped\"]\n    },\n    {\n      \"year\": 2011,\n      \"claim\": \"Synthesized the lipid-remodeling arm of PKD trafficking—PI4KIIIβ activation, CERT/OSBP phosphorylation, and DAG→PA→LPA conversion for fission.\",\n      \"evidence\": \"Review synthesizing biochemical evidence on PI4KIIIβ and CERT/OSBP\",\n      \"pmids\": [\"21421913\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Review format aggregating prior data\", \"Quantitative lipid flux at fission sites not directly resolved\"]\n    },\n    {\n      \"year\": 2012,\n      \"claim\": \"Placed PKD upstream of a mitotic Raf–MEK1 axis controlling Golgi fragmentation and G2/M progression.\",\n      \"evidence\": \"siRNA of PKD1/2, cell cycle analysis, Raf/MEK blots, constitutively active MEK1 rescue, Golgi FRAP\",\n      \"pmids\": [\"23242995\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Direct PKD substrate connecting to Raf-1 activation unknown\", \"Mechanism of mitotic PKD activation not defined\"]\n    },\n    {\n      \"year\": 2013,\n      \"claim\": \"Established PRKD1 as an epigenetically silenced metastasis suppressor in breast cancer whose re-expression maintains the epithelial phenotype.\",\n      \"evidence\": \"Methylation-specific PCR, bisulfite sequencing, decitabine xenograft rescue, invasion and metastasis imaging\",\n      \"pmids\": [\"23971832\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Mechanism of EMT suppression at substrate level not defined here\", \"Reconciliation with pro-invasive substrate phosphorylation unaddressed\"]\n    },\n    {\n      \"year\": 2013,\n      \"claim\": \"Implicated a purinergic→PKC→PKD cascade in Schwann cell GDNF upregulation after nerve injury, extending PKD into neural injury responses.\",\n      \"evidence\": \"Pharmacological PKC/PKD inhibition, siRNA, GDNF expression assays\",\n      \"pmids\": [\"23553603\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Direct transcriptional mechanism unknown\", \"Limited mechanistic detail\"]\n    },\n    {\n      \"year\": 2014,\n      \"claim\": \"Identified the recurrent activating E710D mutation as a likely driver of polymorphous low-grade adenocarcinoma, establishing PRKD1 as a cancer oncogenic alteration.\",\n      \"evidence\": \"Tumor sequencing, functional kinase activity assay of E710D versus wild-type\",\n      \"pmids\": [\"25240283\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Structural basis of constitutive activation not resolved\", \"Downstream oncogenic substrates in PLGA unknown\"]\n    },\n    {\n      \"year\": 2015,\n      \"claim\": \"Showed PKD family kinases mediate GPCR-driven YAP inactivation via Lats2, connecting PKD to Hippo-pathway control of growth genes.\",\n      \"evidence\": \"PKD inhibitors, PKD1/2/3 triple siRNA, phospho-YAP blots, fractionation, target gene qRT-PCR\",\n      \"pmids\": [\"27369082\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Direct PKD substrate in the Lats2/YAP module not identified\", \"Isoform-specific contributions not separated\"]\n    },\n    {\n      \"year\": 2015,\n      \"claim\": \"Defined the GPCR→PLCγ2→PKCβ→PKD1→SSH2 axis driving neutrophil chemotaxis via cofilin/actin control.\",\n      \"evidence\": \"siRNA epistasis, PKCβ-PKD1 co-IP, in vitro SSH2 kinase assay, cofilin blots, chemotaxis assays\",\n      \"pmids\": [\"25568344\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"SSH2 phospho-site not mapped here\", \"Reconciliation with other PKD migratory roles unclear\"]\n    },\n    {\n      \"year\": 2015,\n      \"claim\": \"Identified PRKD1 as a direct Twist1 transcriptional target required for epithelial dissemination via β-catenin and Tau phosphorylation, revealing a context-dependent pro-metastatic role.\",\n      \"evidence\": \"3D mammary organoids, Twist1 overexpression, ChIP-PCR, Prkd1 inhibition/shRNA, phosphoproteomics, in vivo tumor model\",\n      \"pmids\": [\"31676574\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Direct versus indirect β-catenin/Tau phosphorylation not fully resolved\", \"Reconciliation with PKD1 metastasis-suppressor role context-dependent\"]\n    },\n    {\n      \"year\": 2016,\n      \"claim\": \"Linked PKD-1 to nuclear FoxO1-HDAC7 complex formation repressing endothelial CD36 and driving proangiogenic reprogramming.\",\n      \"evidence\": \"DNA-binding assay, ChIP, FoxO1-HDAC7 co-IP, PLA, angiogenesis assays\",\n      \"pmids\": [\"27013613\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Direct PKD substrate in this complex unknown\", \"Single lab\"]\n    },\n    {\n      \"year\": 2018,\n      \"claim\": \"Defined a Rho network (GEF-H1/DLC3/PLCε) regulating PKD activation at the TGN for focal-adhesion-directed exocytosis.\",\n      \"evidence\": \"Genetically encoded PKD activity reporter, siRNA of Rho components, Rab6 carrier imaging\",\n      \"pmids\": [\"30028295\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"How Rho input integrates with Gβγ/PLCβ3 axis unclear\", \"Single lab\"]\n    },\n    {\n      \"year\": 2021,\n      \"claim\": \"Identified MFF as a mitosis-specific PKD substrate driving mitochondrial fission required for chromosome segregation, extending PKD into mitotic organelle dynamics.\",\n      \"evidence\": \"In vitro kinase assay, phospho-antibody, phospho-mimetic/dead MFF mutants, chromosome segregation and checkpoint assays\",\n      \"pmids\": [\"34010649\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Mechanism restricting MFF phosphorylation to mitosis unknown\", \"Spatial control of mitotic PKD activation undefined\"]\n    },\n    {\n      \"year\": 2022,\n      \"claim\": \"Established the PKD→PARP12→Golgin-97 ADP-ribosylation cascade as a selective mechanism for basolateral E-cadherin carrier fission at the TGN.\",\n      \"evidence\": \"In vitro kinase and ADP-ribosylation assays, mutagenesis of multiple sites, cargo transport and carrier fission imaging\",\n      \"pmids\": [\"34969853\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"PARP12 phospho-site and Golgin-97 acidic cluster generality across cargoes not fully defined\", \"How this integrates with lipid-remodeling fission arm unclear\"]\n    },\n    {\n      \"year\": null,\n      \"claim\": \"How PKD1's opposing roles—epithelial-phenotype maintenance and metastasis suppression versus Twist1-driven pro-dissemination and pro-invasive integrin recycling—are reconciled within a single cell context remains unresolved.\",\n      \"evidence\": \"\",\n      \"pmids\": [],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"No unified model reconciling anti- and pro-metastatic PKD1 outputs\", \"Determinants of substrate selection across contexts unknown\", \"Spatial control of distinct PKD1 activity pools not defined\"]\n    }\n  ],\n  \"mechanism_profile\": {\n    \"molecular_activity\": [\n      {\"term_id\": \"GO:0140096\", \"supporting_discovery_ids\": [0, 3, 16, 22, 30, 33, 34]},\n      {\"term_id\": \"GO:0016740\", \"supporting_discovery_ids\": [0, 7, 16, 22, 33]},\n      {\"term_id\": \"GO:0008289\", \"supporting_discovery_ids\": [6, 12]},\n      {\"term_id\": \"GO:0008092\", \"supporting_discovery_ids\": [15]}\n    ],\n    \"localization\": [\n      {\"term_id\": \"GO:0005794\", \"supporting_discovery_ids\": [6, 9, 11, 14, 18, 24, 34]},\n      {\"term_id\": \"GO:0005829\", \"supporting_discovery_ids\": [4, 5, 9]},\n      {\"term_id\": \"GO:0005886\", \"supporting_discovery_ids\": [4, 5, 15]},\n      {\"term_id\": \"GO:0005634\", \"supporting_discovery_ids\": [31]}\n    ],\n    \"pathway\": [\n      {\"term_id\": \"R-HSA-5653656\", \"supporting_discovery_ids\": [6, 11, 14, 22, 34]},\n      {\"term_id\": \"R-HSA-162582\", \"supporting_discovery_ids\": [1, 11, 29, 35]},\n      {\"term_id\": \"R-HSA-1640170\", \"supporting_discovery_ids\": [24, 33]},\n      {\"term_id\": \"R-HSA-9612973\", \"supporting_discovery_ids\": [20]},\n      {\"term_id\": \"R-HSA-1643685\", \"supporting_discovery_ids\": [25, 27, 28]}\n    ],\n    \"complexes\": [],\n    \"partners\": [\"PRKCH\", \"PRKCE\", \"PLCB3\", \"VPS34\", \"RABEP5\", \"MFF\", \"PARP12\", \"SSH2\"],\n    \"other_free_text\": []\n  }\n}","audit_flag":null,"evaluation":{"pairwise":"win","faith_supported":6,"faith_total":6,"faith_pct":100.0}}