{"gene":"OCRL","run_date":"2026-06-10T05:19:52","timeline":{"discoveries":[{"year":1998,"finding":"OCRL encodes an inositol polyphosphate 5-phosphatase with marked preference for phosphatidylinositol 4,5-bisphosphate (PI(4,5)P2), also hydrolyzing IP3, IP4, and PI(3,4,5)P3; it is the major PI(4,5)P2 5-phosphatase in kidney proximal tubule cells, and its loss leads to PI(4,5)P2 accumulation. OCRL protein is associated with lysosomal membranes in proximal tubule cells.","method":"In vitro enzymatic assay with substrate preference testing; cell lines from Lowe syndrome patient kidney proximal tubules lacking OCRL protein; lipid quantification showing PI(4,5)P2 accumulation; subcellular fractionation/immunolocalization to lysosomes","journal":"The Journal of biological chemistry","confidence":"High","confidence_rationale":"Tier 1 / Strong — direct in vitro enzymatic assay establishing substrate specificity plus cell-based functional demonstration with patient-derived cells; replicated by subsequent studies","pmids":["9430698"],"is_preprint":false},{"year":2000,"finding":"OCRL1 (Ocrl1) localizes to the trans-Golgi network (TGN) in fibroblasts and kidney epithelial cells, as determined by immunofluorescence, subcellular fractionation, and brefeldin A perturbation assay.","method":"Immunofluorescence co-localization with TGN markers, subcellular fractionation, brefeldin A dynamic perturbation assay","journal":"The journal of histochemistry and cytochemistry","confidence":"High","confidence_rationale":"Tier 2 / Strong — three orthogonal methods in multiple cell types; replicated by many subsequent studies","pmids":["10639484"],"is_preprint":false},{"year":2003,"finding":"OCRL1 interacts with activated Rac GTPase via its C-terminal RhoGAP domain both in vitro and by co-immunoprecipitation with endogenous OCRL1. A fraction of endogenous Rac co-localizes with OCRL1 and γ-adaptin in the TGN. The OCRL1 RhoGAP domain shows low Rac GAP activity in vitro and inhibits Rac-GTP-dependent membrane ruffles when expressed in cells.","method":"GST pulldown (in vitro binding), co-immunoprecipitation, immunofluorescence co-localization, in vitro GAP activity assay, Swiss 3T3 cell ruffle assay","journal":"Human molecular genetics","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — reciprocal Co-IP plus in vitro assay plus functional cell readout, single lab","pmids":["12915445"],"is_preprint":false},{"year":2004,"finding":"OCRL localizes to endosomes and Golgi membranes in association with clathrin; it interacts directly with the clathrin terminal domain and clathrin adaptor AP-2, as shown by GST binding assays. Live-cell imaging confirmed dynamic OCRL localization on endosomes.","method":"Fluorescence microscopy (fixed and live-cell time-lapse), GST pulldown binding assay with clathrin terminal domain and AP-2","journal":"Proceedings of the National Academy of Sciences of the United States of America","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — direct binding assay plus live-cell imaging, single lab","pmids":["15353600"],"is_preprint":false},{"year":2005,"finding":"OCRL1 is associated with clathrin-coated transport intermediates between the TGN and endosomes, interacts directly with clathrin heavy chain, and promotes clathrin assembly in vitro. Overexpression of OCRL1 causes redistribution of clathrin and CI-MPR to enlarged endosomal structures defective in retrograde trafficking to the TGN; depletion of OCRL1 causes partial redistribution of CI-MPR to early endosomes.","method":"Co-immunoprecipitation, direct clathrin assembly assay in vitro, overexpression and siRNA knockdown with immunofluorescence readout for CI-MPR trafficking","journal":"Molecular biology of the cell","confidence":"High","confidence_rationale":"Tier 1-2 / Strong — in vitro clathrin assembly assay plus reciprocal Co-IP plus loss/gain-of-function cellular trafficking assays","pmids":["15917292"],"is_preprint":false},{"year":2006,"finding":"OCRL1 interacts with multiple Rab GTPases (Rab1, Rab5, Rab6 most strongly). Rab binding is required for targeting OCRL1 to the Golgi and endosomes, as point mutants defective in Rab binding fail to localize to these compartments. In vitro experiments demonstrate that Rab5 and Rab6 directly stimulate the 5-phosphatase activity of OCRL1.","method":"Co-immunoprecipitation, pulldown, point mutagenesis with subcellular localization readout, in vitro 5-phosphatase activity assay with Rab proteins","journal":"The EMBO journal","confidence":"High","confidence_rationale":"Tier 1-2 / Strong — in vitro enzymatic stimulation assay plus mutagenesis plus localization, replicated by structural studies","pmids":["16902405"],"is_preprint":false},{"year":2006,"finding":"Missense mutations I751N and A780P in the RhoGAP-homology domain of OCRL1 reduce enzyme (PI(4,5)P2 5-phosphatase) activity by 85-90% without affecting protein expression levels, demonstrating that the RhoGAP domain is important for enzymatic function. Wild-type but not the I751N mutant OCRL1 co-immunoprecipitates with Arf1 and Arf6, indicating the RhoGAP domain mediates interaction with Arf GTPases.","method":"In vitro phosphatase activity assay, co-immunoprecipitation with Arf1 and Arf6","journal":"Molecular genetics and metabolism","confidence":"Medium","confidence_rationale":"Tier 1-2 / Moderate — enzymatic assay and Co-IP, single lab","pmids":["16777452"],"is_preprint":false},{"year":2007,"finding":"OCRL visits late-stage endocytic clathrin-coated pits and binds the Rab5 effector APPL1 on peripheral early endosomes. The interaction with APPL1 is mediated by the ASH-RhoGAP-like domains of OCRL and is abolished by disease-causing mutations. Crystallographic studies reveal a role of the ASH-RhoGAP-like domains in positioning the phosphatase domain at the membrane interface and show a clathrin box protruding from the RhoGAP-like domain.","method":"Co-immunoprecipitation, live-cell imaging, X-ray crystallography, disease-mutation analysis","journal":"Developmental cell","confidence":"High","confidence_rationale":"Tier 1 / Strong — crystal structure plus Co-IP plus functional mutagenesis in a single study","pmids":["17765681"],"is_preprint":false},{"year":2008,"finding":"All known disease-causing missense mutations in the ASH-RhoGAP domains of OCRL abolish the interaction with endocytic adaptor APPL1, which is the only OCRL interaction (among those tested) disrupted by all such mutations. APPL1 and Rab5 independently contribute to recruit OCRL to enlarged endosomes.","method":"Co-immunoprecipitation, expression of constitutively active Rab5, disease-mutation analysis","journal":"Biochemical and biophysical research communications","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — multiple Co-IP with systematic mutation analysis, single lab","pmids":["18307981"],"is_preprint":false},{"year":2008,"finding":"OCRL1 (via its homolog Dd5P4 in Dictyostelium) restricts intracellular growth of Legionella pneumophila. OCRL1 localizes to Legionella-containing vacuoles (LCVs) in macrophages. The N-terminal domain of OCRL1 binds the Legionella effector LpnE. Complementation with catalytically inactive Dd5P4 fails to rescue the phenotype, demonstrating catalytic activity is required.","method":"Genetic complementation in Dictyostelium discoideum, fluorescence microscopy localization to LCVs, GST pulldown binding assay with LpnE, catalytically inactive mutant analysis","journal":"Cellular microbiology","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — genetic complementation with catalytic mutant plus direct binding assay, single lab","pmids":["19021631"],"is_preprint":false},{"year":2009,"finding":"OCRL1 isoform a (brain-specific longer isoform) binds clathrin with higher affinity than isoform b and is significantly more enriched in clathrin-coated trafficking intermediates. A second clathrin-binding site was identified in OCRL1. Association with clathrin-coated intermediates requires Rab GTPase-mediated membrane association but not AP2 binding. Expression of the 5-phosphatase-deleted isoform a (but not isoform b equivalent) impairs transferrin endocytosis.","method":"Clathrin binding assays, subcellular fractionation, fluorescence microscopy, transferrin endocytosis assay","journal":"The Journal of biological chemistry","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — direct binding assay plus functional endocytosis assay, single lab","pmids":["19211563"],"is_preprint":false},{"year":2009,"finding":"Lowe syndrome patient fibroblasts lacking OCRL1 display defects in cell migration, spreading, and fluid-phase uptake. These defects are rescued by wild-type OCRL1 but not a phosphatase-deficient mutant, nor by the paralog Inpp5b. OCRL1 variants lacking AP2 or clathrin binding were less able to rescue migration, implicating these interactions in ruffle-mediated membrane remodeling.","method":"Cell migration assay, spreading assay, fluid-phase uptake assay, rescue with WT and mutant OCRL1 constructs in patient fibroblasts","journal":"Human molecular genetics","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — patient cells plus rescue with multiple mutants, single lab","pmids":["19700499"],"is_preprint":false},{"year":2010,"finding":"Two endocytic proteins Ses1 and Ses2 (IPIP27A/B) interact with OCRL via a short phenylalanine and histidine (F&H) motif in the ASH-RhoGAP-like domain, the same site used by APPL1. Ses binding is mutually exclusive with APPL1 binding and is disrupted by the same disease-causing missense mutations.","method":"Co-immunoprecipitation, pulldown, competition binding assay, disease-mutation analysis","journal":"Proceedings of the National Academy of Sciences of the United States of America","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — reciprocal Co-IP with competition assay and systematic mutation analysis, single lab","pmids":["20133602"],"is_preprint":false},{"year":2011,"finding":"Active (GTP-bound) Rab35 directly interacts with OCRL and controls its localization at the intercellular bridge during cytokinesis. Depletion of Rab35 or OCRL inhibits cytokinesis abscission and causes local PI(4,5)P2 and F-actin accumulation in the intercellular bridge. Division defects in Lowe patient cell lines are rescued by low doses of F-actin depolymerization drugs, establishing that OCRL-mediated PI(4,5)P2 hydrolysis is required for F-actin remodeling during abscission.","method":"Pulldown with active Rab35, siRNA depletion, live-cell imaging, fluorescence microscopy, pharmacological rescue with F-actin depolymerizing drugs, patient cell lines","journal":"Nature cell biology","confidence":"High","confidence_rationale":"Tier 2 / Strong — direct binding assay plus loss-of-function with defined phenotypic readout plus patient cells plus pharmacological rescue, replicated by Drosophila work","pmids":["21706022"],"is_preprint":false},{"year":2011,"finding":"OCRL controls early endosome (EE) function via its 5-phosphatase activity. OCRL depletion impairs recycling of multiple receptors including megalin, causing their retention in engorged EEs. The trafficking defects result from ectopic PI(4,5)P2 accumulation in EEs, which induces N-WASP-dependent increase in endosomal F-actin.","method":"siRNA knockdown, receptor recycling assays, lipid imaging, N-WASP manipulation, fluorescence microscopy","journal":"The EMBO journal","confidence":"High","confidence_rationale":"Tier 2 / Strong — multiple orthogonal methods including receptor trafficking, lipid imaging, and N-WASP epistasis, replicated across labs","pmids":["21971085"],"is_preprint":false},{"year":2011,"finding":"OCRL and Inpp5B are recruited to nascent phagosomes as Rab5 effectors via the adaptor protein APPL1. Knockdown of APPL1 or inhibition of Rab5 impairs association of OCRL and Inpp5B with phagosomes and prolongs PI(4,5)P2 and actin presence on phagosomal membranes. APPL1 depletion accentuates Akt activation, linked to increased PI(4,5)P2 available for PI(3,4,5)P3 generation.","method":"siRNA knockdown, fluorescence microscopy, lipid imaging on phagosomes, Akt activation assay","journal":"Molecular biology of the cell","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — loss-of-function with multiple readouts, single lab","pmids":["22072788"],"is_preprint":false},{"year":2011,"finding":"IPIP27A and IPIP27B (Ses1 and Ses2) bind OCRL1 and the related phosphatase Inpp5b via a conserved motif in the C-terminal region of these phosphatases. IPIP27A/B localize to early and recycling endosomes and the TGN, form homo- and heterodimers, and are required for receptor recycling from endosomes both to the TGN and to the plasma membrane.","method":"Co-immunoprecipitation, siRNA knockdown with receptor recycling assays, fluorescence microscopy","journal":"Molecular biology of the cell","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — Co-IP plus functional recycling assay, single lab","pmids":["21233288"],"is_preprint":false},{"year":2011,"finding":"Crystal structure of the Rab-binding domain (RBD/ASH domain) of OCRL1 in complex with Rab8a reveals that the Rab-binding interface consists mainly of the IgG-like β-strand structure of the ASPM-SPD-2-Hydin domain plus one α-helix, distinct from other Rab effectors. Kinetic analysis showed binding to Rab1b, Rab5a, Rab6a, and Rab8a. Disease-causing mutations in the RBD affect Rab binding.","method":"X-ray crystallography, kinetic binding analysis (surface plasmon resonance), disease-mutation analysis","journal":"The EMBO journal","confidence":"High","confidence_rationale":"Tier 1 / Strong — crystal structure plus kinetic binding characterization plus disease-mutation functional annotation","pmids":["21378754"],"is_preprint":false},{"year":2011,"finding":"X-ray crystallography of the OCRL RhoGAP domain identified the F&H motif binding site. Disease-associated missense mutations in the ASH-RhoGAP domain disrupt F&H binding indirectly by destabilizing the RhoGAP fold. A disease mutation that does not perturb F&H binding and ASH-RhoGAP stability instead disrupts the interaction of OCRL with Rab5.","method":"X-ray crystallography, binding assays, mutagenesis with functional analysis of APPL1/Ses binding and Rab5 binding","journal":"Nature structural & molecular biology","confidence":"High","confidence_rationale":"Tier 1 / Strong — crystal structure plus mutagenesis plus binding assays distinguishing two classes of disease mutations","pmids":["21666675"],"is_preprint":false},{"year":2012,"finding":"OCRL localizes to the primary cilium of retinal pigment epithelial cells, fibroblasts, and kidney tubular cells. Lowe syndrome-associated mutations in OCRL result in shortened cilia, rescued by wild-type OCRL re-expression. In vivo, knockdown of ocrl in zebrafish causes defective cilia formation in Kupffer's vesicles and cilia-dependent phenotypes.","method":"Fluorescence microscopy of primary cilia, rescue experiments with WT OCRL, zebrafish morpholino knockdown","journal":"Human molecular genetics","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — direct localization plus rescue plus in vivo model, single lab","pmids":["22543976"],"is_preprint":false},{"year":2012,"finding":"OCRL1 is required for primary cilia assembly; patient cells and OCRL1 knockdown cells show defects in cilia assembly rescued by WT OCRL1. OCRL1 is involved in protein trafficking to the primary cilia in a Rab8- and IPIP27/Ses-dependent manner.","method":"siRNA knockdown, rescue with WT OCRL1, patient cell lines, zebrafish model, fluorescence microscopy, trafficking assays","journal":"Human molecular genetics","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — patient cells plus rescue plus in vivo zebrafish model, single lab","pmids":["22228094"],"is_preprint":false},{"year":2012,"finding":"OCRL loss in Lowe syndrome patient fibroblasts impairs clathrin-mediated endocytosis, causing accumulation of clathrin-coated vesicles and U-shaped clathrin-coated pits. Endocytic vesicles that fail to shed their coat nucleate actin comets. SNX9, which couples late-stage endocytic pits to actin polymerization, binds OCRL directly and remains associated with uncoated vesicles in patient cells, establishing OCRL as an uncoating factor.","method":"Patient fibroblast analysis, electron microscopy, direct pulldown of SNX9-OCRL, fluorescence microscopy of coated vesicles and actin comets","journal":"eLife","confidence":"High","confidence_rationale":"Tier 2 / Strong — patient cells plus direct binding assay plus ultrastructural analysis, multiple orthogonal methods","pmids":["25107275"],"is_preprint":false},{"year":2012,"finding":"OCRL depletion in HeLa cells decreases endosome-to-TGN transport of the mannose 6-phosphate receptor (MPR), leading to its accumulation in enlarged retromer-positive endosomes and higher surface levels of MPR. Wild-type OCRL rescues MPR accumulation in an activity-dependent manner. OCRL depletion increases inactive phospho-cofilin and reduces active Rac1, while increasing active RhoA; overexpression of Rac1 rescues both cofilin phosphorylation and MPR accumulation, establishing a PI(4,5)P2–Rac1–cofilin signaling module downstream of OCRL.","method":"siRNA knockdown, fluorescence microscopy, receptor trafficking assays, GTPase activation assays (pulldown), cofilin phosphorylation immunoblotting, rescue by Rac1 overexpression","journal":"Human molecular genetics","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — multiple pathway readouts plus rescue epistasis, single lab","pmids":["22907655"],"is_preprint":false},{"year":2012,"finding":"OCRL controls PI(4,5)P2 levels at the surface of endosomes during cytokinesis, restricting PI(4,5)P2 to the cell cortex. Drosophila dOCRL (ortholog of human OCRL1) is essential for cytokinesis, acting to dephosphorylate PI(4,5)P2 at endosomal surfaces.","method":"Drosophila genetic loss-of-function, live-cell imaging, PI(4,5)P2 reporters","journal":"Communicative & integrative biology","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — genetic loss-of-function in a model organism with defined molecular readout, single lab","pmids":["22896796"],"is_preprint":false},{"year":2012,"finding":"OCRL suppresses the intestinal calcium channel TRPV6 via two separate mechanisms: (1) the PI(4,5)P2 5-phosphatase domain suppresses TRPV6-mediated Ca2+ transport by reducing PI(4,5)P2 levels without affecting TRPV6 surface abundance; (2) the Rab-binding domain regulates forward trafficking of TRPV6 to the cell surface. Dent-causing OCRL mutations alleviate inhibition of TRPV6-mediated Ca2+ transport.","method":"Xenopus oocyte expression system, Ca2+ uptake assays, cell surface quantification, antisense OCRL knockdown in Xenopus, Dent-mutation analysis","journal":"American journal of physiology. Cell physiology","confidence":"Medium","confidence_rationale":"Tier 1-2 / Moderate — functional assay in heterologous expression system with domain dissection and loss-of-function, single lab","pmids":["22378746"],"is_preprint":false},{"year":2012,"finding":"Through its phosphatase activity, OCRL restricts Listeria monocytogenes invasion by modulating PI(4,5)P2 and PI(3,4,5)P3 levels and actin dynamics at bacterial internalization foci. OCRL accumulates at invasion foci coincident with actin depolymerization; catalytically dead OCRL fails to rescue the phenotype.","method":"siRNA knockdown, live-cell imaging, fluorescence microscopy, rescue with enzymatically active vs. dead OCRL-a","journal":"The Journal of biological chemistry","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — loss-of-function plus catalytic dead rescue, single lab","pmids":["22351770"],"is_preprint":false},{"year":2012,"finding":"Bcl10 delivers the OCRL phosphatase to phagocytic cups via a complex with clathrin adaptors AP1 and EpsinR. OCRL locally regulates PI(4,5)P2 and F-actin turnover required for phagosome closure.","method":"Co-immunoprecipitation, siRNA knockdown, fluorescence microscopy, phagocytosis assays in human macrophages","journal":"Developmental cell","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — Co-IP complex identification plus loss-of-function with defined phagocytic readout, single lab","pmids":["23153494"],"is_preprint":false},{"year":2015,"finding":"Rab35 GTPase acts as a switch for OCRL recruitment on newborn endosomes immediately after scission of clathrin-coated vesicles (CCVs). Rab35 loading on CCVs follows DENND1A recruitment and EPI64B disappearance. Depletion of Rab35 or OCRL causes retention of CI-MPR in peripheral clathrin-positive endosomes with abnormal PI(4,5)P2 and actin-binding proteins.","method":"Live-cell imaging, siRNA knockdown, direct binding assays, fluorescence microscopy of endogenous receptors and lipids","journal":"Current biology","confidence":"High","confidence_rationale":"Tier 2 / Strong — direct binding plus loss-of-function for both proteins with defined trafficking readout plus mechanistic dissection of Rab35 GEF/GAP cycle, single lab with multiple orthogonal approaches","pmids":["26725203"],"is_preprint":false},{"year":2015,"finding":"OCRL1 is required for endocytosis in the zebrafish pronephric tubule in vivo; OCRL1 deficiency causes reduced megalin levels and accumulation in endocytic compartments, reduced numbers of early endosomes, and enlarged vacuolar endosomes. Catalytic activity of OCRL1 is required for renal tubular endocytosis, and the endocytic defect is rescued by suppression of PIP5K.","method":"Zebrafish ocrl1 mutant model, fluorescence/electron microscopy, endocytosis assays, rescue by PIP5K suppression","journal":"PLoS genetics","confidence":"High","confidence_rationale":"Tier 2 / Strong — in vivo genetic model with defined endocytic readout plus catalytic mutant analysis plus epistasis via PIP5K suppression","pmids":["25838181"],"is_preprint":false},{"year":2015,"finding":"OCRL1 interacts with F-BAR protein pacsin 2 via IPIP27A. OCRL1 and IPIP27A localize to MPR-containing trafficking intermediates; loss of either protein impairs MPR carrier biogenesis at TGN and endosomes. OCRL1 5-phosphatase activity (which is stimulated by membrane curvature and further by IPIP27A-mediated engagement with pacsin 2) promotes scission of MPR-containing carriers.","method":"Co-immunoprecipitation, siRNA knockdown, live-cell imaging, MPR trafficking assay, in vitro phosphatase activity assay with membrane curvature","journal":"Molecular biology of the cell","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — Co-IP plus functional trafficking assay plus enzymatic assay with curvature sensitivity, single lab","pmids":["26510499"],"is_preprint":false},{"year":2015,"finding":"OCRL1 acts as a RacGAP in chondrocytes. Overexpression of OCRL1 inhibits Rac1 activity and chondrocyte hypertrophy; knockdown elevates Rac1 activity and promotes hypertrophy/mineralization. The GAP activity requires the GAP domain. Intraarticular injection of OCRL1-encoding lentivirus protects against cartilage destruction in a mouse OA model.","method":"Rac1 activity pulldown assay, lentiviral overexpression and knockdown, alkaline phosphatase staining, mouse OA intraarticular injection model","journal":"Arthritis & rheumatology","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — direct GTPase activity assay plus domain mutant analysis plus in vivo model, single lab","pmids":["25917196"],"is_preprint":false},{"year":2016,"finding":"OCRL plays a key role in a lysosomal response to autophagosome-lysosome fusion. Mitochondrial DNA delivered by autophagosomes activates TLR9 as cargo/receptor. A local, transient increase in PI(4,5)P2 is confined by OCRL. OCRL depletion causes accumulation of lysosomal PI(4,5)P2, which inhibits the calcium channel mucolipin-1, blocking autophagosome-lysosome fusion. Boosting mucolipin-1 activity with agonists restores autophagic flux in Lowe syndrome patient cells.","method":"siRNA knockdown, Lowe patient cell lines, PI(4,5)P2 and mucolipin-1 functional assays, TLR9/mtDNA identification as cargo/receptor, pharmacological rescue","journal":"Nature cell biology","confidence":"High","confidence_rationale":"Tier 2 / Strong — multiple orthogonal methods including molecular identification of cargo/receptor, lipid imaging, pharmacological rescue in patient cells, single high-rigor study","pmids":["27398910"],"is_preprint":false},{"year":2017,"finding":"OCRL loss increases PI(4,5)P2 and decreases PI4P in primary cilia, with PI(4,5)P2 build-up particularly at the transition zone. This is reversed by reintroduction of OCRL. In Lowe syndrome mouse model MEFs, accumulation of sonic hedgehog in response to hedgehog agonist is decreased.","method":"Fluorescence microscopy with PI(4,5)P2 and PI4P reporters in patient fibroblasts and MEFs from Lowe mouse model; rescue with WT OCRL; Hedgehog pathway readout","journal":"Journal of cell science","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — direct lipid measurement in cilia plus rescue plus signaling readout, single lab","pmids":["28871046"],"is_preprint":false},{"year":2019,"finding":"In a humanized mouse model (OcrlY/- with human INPP5B rescue of Inpp5b lethality), OCRL deficiency causes massive urinary loss of low-molecular-weight proteins and albumin due to selective impairment of receptor-mediated endocytosis in proximal tubule cells. PI(4,5)P2 accumulation in endolysosomes drives local F-actin hyper-polymerization, impairing trafficking of the LRP2 endocytic receptor. OCRL deficiency also disrupts lysosomal dynamics and proteolytic activity.","method":"Humanized mouse model, primary mPTC culture, urine analysis, fluorescence microscopy, F-actin quantification, receptor trafficking assay for LRP2","journal":"Human molecular genetics","confidence":"High","confidence_rationale":"Tier 2 / Strong — in vivo mouse model plus primary cell culture with mechanistic dissection of PI(4,5)P2–F-actin–LRP2 axis, multiple orthogonal readouts","pmids":["30590522"],"is_preprint":false},{"year":2021,"finding":"Rab5 recruits OCRL and Inpp5b to macropinosomes via APPL1, downstream of membrane ruffling. This recruitment mediates PI(4,5)P2 removal required for macropinosome sealing/scission. Knockdown of OCRL and Inpp5b, or APPL1, prevents macropinosome closure without affecting ruffling.","method":"siRNA knockdown, dominant-negative Rab5, fluorescence microscopy, PI(4,5)P2 imaging, macropinocytosis assay","journal":"Journal of cell science","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — loss-of-function with defined readout and pathway dissection, single lab","pmids":["33722976"],"is_preprint":false},{"year":2021,"finding":"Legionella effector SdhA binds the OCRL ASH domain and blocks OCRL's interactions with Rab GTPases (without directly altering its catalytic 5-phosphatase activity), thereby hijacking OCRL function to maintain vacuole integrity. OCRL depletion enhances vacuole integrity and intracellular growth of a sdhA mutant. Overexpressed SdhA causes endosomal PI(4,5)P2 accumulation and interferes with endosomal trafficking.","method":"Co-immunoprecipitation, OCRL knockdown, fluorescence microscopy of vacuole integrity and endosomal markers, in vitro binding assay mapping interaction to ASH domain, 5-phosphatase activity assay","journal":"Cell reports","confidence":"High","confidence_rationale":"Tier 1-2 / Strong — direct binding assay with domain mapping plus activity assay plus genetic loss-of-function with defined vacuole phenotype, multiple orthogonal methods","pmids":["34731604"],"is_preprint":false},{"year":2021,"finding":"OCRL deficiency in megakaryocytes and platelets causes defective actomyosin cytoskeleton reorganization: reduced Rac1 activity, elevated active RhoA, increased phosphorylated (inactive) myosin light chain (P-MLC), resulting in deficient proplatelet extension and impaired platelet spreading and clot retraction. OCRL depletion with siOCRL in control MKs reproduces the proplatelet extension defect.","method":"Case-control study on patient platelets/MKs, GTPase activation pulldown assay, MLC phosphorylation immunoblotting, siRNA knockdown in MKs, flow-based thrombus formation assay","journal":"British journal of haematology","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — patient cells plus siRNA validation plus multiple functional readouts, single lab","pmids":["33528045"],"is_preprint":false},{"year":2022,"finding":"A novel OCRL protein isoform translated from exon 8 (80 kDa) retains equivalent 5-phosphatase enzyme activity to full-length OCRL. Truncating mutations in exons 1–7 (Dent disease-2) produce this shorter functional isoform with >50% activity, whereas truncating mutations in exons 8–24 (Lowe syndrome) produce no detectable protein and <20% activity, explaining the phenotypic difference between the two diseases.","method":"mRNA cloning from patient urine-derived cells, in vitro protein expression analysis, 5-phosphatase activity assay, transfection into HeLa cells","journal":"Nephrology, dialysis, transplantation","confidence":"High","confidence_rationale":"Tier 1 / Strong — direct enzymatic activity assay plus in vitro protein expression with multiple disease variants establishing molecular basis for genotype-phenotype correlation","pmids":["34586410"],"is_preprint":false},{"year":1998,"finding":"Targeted disruption of mouse Ocrl1 produces no phenotype (no cataracts, renal Fanconi syndrome, or neurological abnormalities), but double knockout of Ocrl1 and Inpp5b results in embryonic lethality with no live-born mice, demonstrating overlapping essential functions of the two paralogs in mice.","method":"Targeted gene disruption in mice (Ocrl1-/- and Inpp5b-/-), double mutant crosses, embryo analysis","journal":"The Journal of clinical investigation","confidence":"High","confidence_rationale":"Tier 2 / Strong — genetic epistasis by double knockout; embryonic lethality as unambiguous readout; replicated by subsequent studies","pmids":["9593760"],"is_preprint":false},{"year":2016,"finding":"Kidney tubule-specific inactivation of Inpp5b on a global Ocrl-knockout mouse background results in low molecular weight proteinuria, phosphaturia, acidemia, and striking impairment of clathrin-dependent and -independent endocytosis in proximal tubules, phenocopying Dent disease caused by mutations in ClC-5.","method":"Conditional knockout mouse model (tubule-specific Inpp5b deletion on global Ocrl-/- background), urine analysis, electron microscopy of proximal tubules, endocytosis assays","journal":"Journal of the American Society of Nephrology","confidence":"High","confidence_rationale":"Tier 2 / Strong — conditional double-knockout mouse with organ-specific readout and defined endocytic phenotype","pmids":["27895154"],"is_preprint":false},{"year":2005,"finding":"Upon EGF-induced Rac activation in COS-7 cells, a fraction of OCRL1 translocates from the TGN to plasma membrane ruffles. In Lowe patient fibroblasts, PI(4,5)P2 accumulates strikingly in PDGF-induced ruffles compared with controls, indicating OCRL1 is active as a PI(4,5)P2 5-phosphatase in Rac-induced membrane ruffles.","method":"Fluorescence microscopy in live/fixed cells, GFP-PH domain PI(4,5)P2 reporter, patient fibroblast vs control comparison, growth factor stimulation","journal":"Human molecular genetics","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — direct localization experiment with functional consequence (lipid accumulation in patient cells), single lab","pmids":["15829501"],"is_preprint":false},{"year":2010,"finding":"Rab31 interacts with OCRL-1 in oligodendrocytes (yeast two-hybrid, GST pulldown, co-immunoprecipitation) and recruits OCRL-1 to TGN domains where MPR-containing carrier formation occurs. siRNA depletion of Rab31 markedly decreases OCRL-1 levels in the TGN and endosomes. MPR is sorted to OCRL-1-containing carriers.","method":"Yeast two-hybrid, GST pulldown, co-immunoprecipitation, siRNA knockdown, fluorescence microscopy","journal":"Journal of neuroscience research","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — three binding assays plus functional depletion, single lab","pmids":["19795375"],"is_preprint":false},{"year":2011,"finding":"OCRL1 localizes to intercellular junctions at early stages of their formation, co-localizing with adherens and tight junctional components and forming complexes with α-catenin and ZO-1/2/3. Depletion of OCRL1 in epithelial sheets inhibits maturation, polarity, and proliferation; this effect requires the 5-phosphatase domain and is rescued by re-expressed OCRL1. In 3D cultures, OCRL1-depleted cells fail to form a central lumen and show incorrect ZO-1 distribution.","method":"Co-immunoprecipitation with junctional proteins, siRNA knockdown, rescue with WT and phosphatase-dead OCRL1, fluorescence microscopy in 2D and 3D culture","journal":"PloS one","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — Co-IP plus knockdown/rescue with domain-function analysis, single lab","pmids":["21901156"],"is_preprint":false}],"current_model":"OCRL is an X-linked inositol polyphosphate 5-phosphatase that preferentially dephosphorylates PI(4,5)P2 (and to a lesser extent PI(3,4,5)P3) at the trans-Golgi network, endosomes, clathrin-coated pits/vesicles, phagosomes, macropinosomes, and the primary cilium; it is recruited to these membranes by multiple Rab GTPases (especially Rab5, Rab35, Rab8) whose binding to its ASH-RhoGAP domain simultaneously stimulates catalytic activity, while endocytic adaptors APPL1, Ses1/2 (IPIP27A/B), and SNX9 further anchor OCRL at specific endocytic compartments; by locally reducing PI(4,5)P2, OCRL controls F-actin remodeling (via N-WASP and cofilin/Rac1 pathways), clathrin coat shedding from endocytic vesicles, cargo recycling (including megalin/LRP2) from early endosomes to the plasma membrane and TGN, cytokinesis abscission, ciliogenesis, and autophagosome–lysosome fusion, with loss of OCRL function causing PI(4,5)P2 accumulation at endolysosomes, aberrant F-actin polymerization, and defective membrane trafficking that underlies the renal, ocular, and neurological phenotypes of Lowe syndrome and Dent disease 2."},"narrative":{"mechanistic_narrative":"OCRL is an X-linked inositol polyphosphate 5-phosphatase that preferentially hydrolyzes PI(4,5)P2 and is the major PI(4,5)P2 5-phosphatase of kidney proximal tubule cells, where its loss causes PI(4,5)P2 accumulation [PMID:9430698]. The enzyme operates across the secretory and endocytic system — the trans-Golgi network, clathrin-coated transport intermediates, early and recycling endosomes, phagosomes, macropinosomes, and the primary cilium — by being recruited to specific membranes through its ASH-RhoGAP module [PMID:10639484, PMID:15353600, PMID:15917292, PMID:22543976]. Recruitment and catalysis are coupled: multiple Rab GTPases (Rab1, Rab5, Rab6, Rab8, Rab35) bind the ASH (Rab-binding) domain through an IgG-like β-strand interface and directly stimulate 5-phosphatase activity, so that membrane targeting and enzymatic action are activated together [PMID:16902405, PMID:16777452, PMID:21378754, PMID:26725203]. A conserved F&H motif in the same module engages the endocytic adaptors APPL1 and Ses1/2 (IPIP27A/B) in a mutually exclusive manner, and these interactions are uniformly abolished by disease-causing missense mutations, which act either by destabilizing the RhoGAP fold or by disrupting Rab5 binding [PMID:17765681, PMID:20133602, PMID:21666675]. By locally removing PI(4,5)P2, OCRL drives clathrin coat shedding and uncoating via SNX9, restrains N-WASP- and Rac1/cofilin-dependent F-actin polymerization, and promotes carrier scission and receptor recycling, including endosome-to-TGN transport of the mannose-6-phosphate receptor and recycling of the endocytic receptor megalin/LRP2 [PMID:21971085, PMID:25107275, PMID:22907655, PMID:26725203, PMID:30590522]. The same lipid-control function underlies abscission during cytokinesis, ciliogenesis and ciliary lipid identity, macropinosome and phagosome sealing, and a lysosomal PI(4,5)P2–mucolipin-1 signal that permits autophagosome–lysosome fusion [PMID:21706022, PMID:22228094, PMID:27398910, PMID:28871046, PMID:33722976]. OCRL and its paralog INPP5B have overlapping essential functions: single Ocrl loss is tolerated in mice while combined loss is embryonic-lethal, and proximal-tubule endocytic failure with PI(4,5)P2-driven F-actin hyperpolymerization underlies the renal phenotype [PMID:30590522, PMID:9593760, PMID:27895154]. Loss-of-function mutations in OCRL cause Lowe syndrome and Dent disease 2, with the milder Dent-2 phenotype explained by an exon-8-derived 80 kDa isoform that retains 5-phosphatase activity when N-terminal truncations spare it [PMID:34586410].","teleology":[{"year":1998,"claim":"Establishing OCRL's biochemical identity answered what the gene product does enzymatically and linked its loss to a defined lipid imbalance in the affected tissue.","evidence":"In vitro substrate-preference enzymatic assays plus PI(4,5)P2 quantification in Lowe patient proximal-tubule cells lacking OCRL","pmids":["9430698"],"confidence":"High","gaps":["Lysosomal association reported but membrane-recruitment mechanism unknown at this stage","Did not address how a single enzyme deficiency produces multi-organ disease"]},{"year":1998,"claim":"Mouse genetics resolved why OCRL loss is far milder in mice than humans, revealing functional redundancy with the paralog INPP5B.","evidence":"Targeted Ocrl1 and Inpp5b single and double knockouts in mice","pmids":["9593760"],"confidence":"High","gaps":["Molecular basis of paralog redundancy not defined","Did not explain the species-specific phenotypic divergence mechanistically"]},{"year":2000,"claim":"Localizing OCRL to the TGN placed the enzyme at a specific membrane trafficking station rather than diffusely at lysosomes.","evidence":"Immunofluorescence, subcellular fractionation, and brefeldin A perturbation in fibroblasts and kidney epithelial cells","pmids":["10639484"],"confidence":"High","gaps":["Recruitment determinants not identified","Functional consequence of TGN localization untested"]},{"year":2004,"claim":"Linking OCRL physically to clathrin and AP-2 connected the phosphatase to the clathrin coat machinery and to dynamic endosomal trafficking.","evidence":"GST binding assays with clathrin terminal domain and AP-2 plus live-cell imaging on endosomes; clathrin assembly assay and CI-MPR trafficking readouts","pmids":["15353600","15917292"],"confidence":"High","gaps":["Whether clathrin binding precedes or follows membrane targeting unresolved","Catalytic versus scaffolding contribution to retrograde transport not separated"]},{"year":2006,"claim":"Discovery that Rab GTPases both target OCRL and stimulate its activity unified membrane recruitment with catalytic activation into a single regulatory logic.","evidence":"Co-IP and pulldown with Rab1/5/6, point mutants defective in Rab binding, and in vitro 5-phosphatase stimulation assays; RhoGAP-domain disease mutants reducing activity 85-90%","pmids":["16902405","16777452"],"confidence":"High","gaps":["Structural basis of Rab-stimulated activation not yet defined","Why the RhoGAP domain controls enzymatic activity unclear at this stage"]},{"year":2010,"claim":"Identifying the F&H motif and its adaptors (APPL1, Ses1/2) defined how OCRL is anchored to distinct endocytic compartments and why all ASH-RhoGAP disease mutations converge on lost adaptor binding.","evidence":"Co-IP, competition binding assays, and systematic disease-mutation analysis of APPL1 and Ses1/2 (IPIP27A/B) binding","pmids":["18307981","20133602","21233288"],"confidence":"Medium","gaps":["What determines APPL1- versus Ses-bound pools in cells not established","Single-lab Co-IP evidence for the mutual exclusivity model"]},{"year":2011,"claim":"Crystal structures of the Rab-binding and RhoGAP domains explained membrane positioning and partitioned disease mutations into mechanistically distinct classes.","evidence":"X-ray crystallography of the ASH domain–Rab8a complex and of the RhoGAP/F&H site, with SPR kinetics and disease-mutation mapping","pmids":["21378754","21666675","17765681"],"confidence":"High","gaps":["Full-length OCRL architecture and how all modules coordinate on a membrane not resolved","Conformational basis of Rab-stimulated catalysis not directly visualized"]},{"year":2011,"claim":"Connecting OCRL to early-endosome recycling, cytokinesis abscission, and phagosome maturation defined the downstream consequence of local PI(4,5)P2 removal: control of F-actin via N-WASP and Rab35-dependent recruitment.","evidence":"siRNA depletion with receptor recycling, lipid imaging, N-WASP epistasis, Rab35 pulldown, patient cells, and pharmacological F-actin rescue","pmids":["21971085","21706022","22072788","22907655"],"confidence":"High","gaps":["How distinct Rab/adaptor combinations specify each compartment not fully mapped","Relative contribution of actin regulators (N-WASP, cofilin/Rac1) across compartments unclear"]},{"year":2012,"claim":"Establishing OCRL's role in ciliogenesis and ciliary lipid identity extended its trafficking function to a structure central to the renal and developmental phenotypes.","evidence":"Cilium localization, patient/knockdown defects rescued by WT OCRL, Rab8/IPIP27-dependent ciliary trafficking, lipid reporters, and zebrafish knockdown","pmids":["22543976","22228094","28871046"],"confidence":"Medium","gaps":["Direct link between ciliary PI(4,5)P2 control and disease phenotypes not proven","Single-lab in vivo evidence for ciliary trafficking model"]},{"year":2014,"claim":"Identifying OCRL as a clathrin uncoating factor recruited via SNX9 explained how its loss produces persistent coated vesicles and ectopic actin comets.","evidence":"Lowe patient fibroblasts, electron microscopy, and direct SNX9-OCRL pulldown","pmids":["25107275"],"confidence":"High","gaps":["Order of SNX9 binding relative to Rab35 loading not resolved","Whether uncoating is driven by lipid hydrolysis or scaffolding not fully separated"]},{"year":2016,"claim":"Linking OCRL to a lysosomal PI(4,5)P2–mucolipin-1 axis showed how the enzyme governs autophagosome–lysosome fusion and offered a pharmacological correction in patient cells.","evidence":"siRNA, patient cells, mucolipin-1 functional assays, mtDNA/TLR9 cargo identification, and agonist rescue","pmids":["27398910"],"confidence":"High","gaps":["How transient PI(4,5)P2 increase is generated and confined not detailed","Single high-rigor study"]},{"year":2019,"claim":"A humanized mouse model defined the in vivo proximal-tubule mechanism: endolysosomal PI(4,5)P2 accumulation drives F-actin hyperpolymerization that blocks LRP2/megalin trafficking, causing low-molecular-weight proteinuria.","evidence":"OcrlY/- humanized mouse with human INPP5B rescue, primary mPTC culture, F-actin quantification, urine analysis, and LRP2 trafficking assays","pmids":["30590522","25838181","27895154"],"confidence":"High","gaps":["Therapeutic correction of the renal phenotype in vivo not demonstrated","Why other organs are spared in mice while affected in humans unresolved"]},{"year":2022,"claim":"Discovery of an exon-8-derived 80 kDa active isoform provided the molecular basis for the genotype-phenotype split between Dent disease 2 and Lowe syndrome.","evidence":"mRNA cloning from patient cells, in vitro expression, and 5-phosphatase activity assays across disease variants","pmids":["34586410"],"confidence":"High","gaps":["Tissue distribution and physiological role of the short isoform not established","Why residual activity protects against ocular/neurological but not all renal features unclear"]},{"year":null,"claim":"How OCRL's full-length modular architecture coordinates Rab binding, adaptor selection, membrane curvature sensing, and catalytic activation in a single integrated cycle on a membrane remains unresolved.","evidence":"","pmids":[],"confidence":"Medium","gaps":["No full-length structure on a membrane","Mechanism by which the RhoGAP/ASH module allosterically controls the phosphatase domain not defined","Compartment-specific partner choice rules not established"]}],"mechanism_profile":{"molecular_activity":[{"term_id":"GO:0016787","term_label":"hydrolase activity","supporting_discovery_ids":[0,6,37]},{"term_id":"GO:0098772","term_label":"molecular function regulator activity","supporting_discovery_ids":[2,30]},{"term_id":"GO:0060090","term_label":"molecular adaptor activity","supporting_discovery_ids":[7,12,21]}],"localization":[{"term_id":"GO:0005794","term_label":"Golgi apparatus","supporting_discovery_ids":[1,3,29]},{"term_id":"GO:0005768","term_label":"endosome","supporting_discovery_ids":[3,7,14,27]},{"term_id":"GO:0005764","term_label":"lysosome","supporting_discovery_ids":[0,31]},{"term_id":"GO:0005929","term_label":"cilium","supporting_discovery_ids":[19,20,32]},{"term_id":"GO:0005886","term_label":"plasma membrane","supporting_discovery_ids":[40]},{"term_id":"GO:0031410","term_label":"cytoplasmic vesicle","supporting_discovery_ids":[4,10,21]}],"pathway":[{"term_id":"R-HSA-5653656","term_label":"Vesicle-mediated transport","supporting_discovery_ids":[4,14,21,27]},{"term_id":"R-HSA-1640170","term_label":"Cell Cycle","supporting_discovery_ids":[13,23]},{"term_id":"R-HSA-9612973","term_label":"Autophagy","supporting_discovery_ids":[31]},{"term_id":"R-HSA-9609507","term_label":"Protein localization","supporting_discovery_ids":[16,20,29]},{"term_id":"R-HSA-1643685","term_label":"Disease","supporting_discovery_ids":[33,37]}],"complexes":[],"partners":["APPL1","IPIP27A/B (SES1/2)","RAB5","RAB35","RAB8","SNX9","CLATHRIN","RAB6"],"other_free_text":[]}},"prefetch_data":{"uniprot":{"accession":"Q01968","full_name":"Inositol polyphosphate 5-phosphatase OCRL","aliases":["Inositol polyphosphate 5-phosphatase OCRL-1","OCRL-1","Lowe oculocerebrorenal syndrome protein","Phosphatidylinositol 3,4,5-triphosphate 5-phosphatase"],"length_aa":901,"mass_kda":104.2,"function":"Catalyzes the hydrolysis of the 5-position phosphate of phosphatidylinositol 4,5-bisphosphate (PtdIns(4,5)P2) and phosphatidylinositol-3,4,5-bisphosphate (PtdIns(3,4,5)P3), with the greatest catalytic activity towards PtdIns(4,5)P2 (PubMed:10764818, PubMed:15474001, PubMed:7761412, PubMed:9430698). Able also to hydrolyze the 5-phosphate of inositol 1,4,5-trisphosphate and of inositol 1,3,4,5-tetrakisphosphate (PubMed:25869668, PubMed:7761412). Regulates traffic in the endosomal pathway by regulating the specific pool of phosphatidylinositol 4,5-bisphosphate that is associated with endosomes (PubMed:21971085). Involved in primary cilia assembly (PubMed:22228094, PubMed:22543976). Acts as a regulator of phagocytosis, hydrolyzing PtdIns(4,5)P2 to promote phagosome closure, through attenuation of PI3K signaling (PubMed:22072788)","subcellular_location":"Cytoplasmic vesicle, phagosome membrane; Early endosome membrane; Membrane, clathrin-coated pit; Cell projection, cilium, photoreceptor outer segment; Cell projection, cilium; Cytoplasmic vesicle; Endosome; Golgi apparatus, trans-Golgi network; Lysosome","url":"https://www.uniprot.org/uniprotkb/Q01968/entry"},"depmap":{"release":"DepMap","has_data":true,"is_common_essential":false,"resolved_as":"","url":"https://depmap.org/portal/gene/OCRL","classification":"Not Classified","n_dependent_lines":3,"n_total_lines":1208,"dependency_fraction":0.0024834437086092716},"opencell":{"profiled":true,"resolved_as":"","ensg_id":"ENSG00000122126","cell_line_id":"CID000150","localizations":[{"compartment":"cytoplasmic","grade":3},{"compartment":"vesicles","grade":2},{"compartment":"golgi","grade":1}],"interactors":[{"gene":"FAM109A","stoichiometry":10.0},{"gene":"IMPAD1","stoichiometry":0.2},{"gene":"CANX","stoichiometry":0.2},{"gene":"G6PD","stoichiometry":0.2},{"gene":"EIF3C;EIF3CL","stoichiometry":0.2}],"url":"https://opencell.sf.czbiohub.org/target/CID000150","total_profiled":1310},"omim":[{"mim_id":"614240","title":"PH DOMAIN-CONTAINING ENDOCYTIC TRAFFICKING ADAPTOR 2; PHETA2","url":"https://www.omim.org/entry/614240"},{"mim_id":"614239","title":"PH DOMAIN-CONTAINING ENDOCYTIC TRAFFICKING ADAPTOR 1; PHETA1","url":"https://www.omim.org/entry/614239"},{"mim_id":"604297","title":"SYNAPTOJANIN 1; SYNJ1","url":"https://www.omim.org/entry/604297"},{"mim_id":"309000","title":"LOWE OCULOCEREBRORENAL SYNDROME; OCRL","url":"https://www.omim.org/entry/309000"},{"mim_id":"300555","title":"DENT DISEASE 2; DENT2","url":"https://www.omim.org/entry/300555"}],"hpa":{"profiled":true,"resolved_as":"","reliability":"Approved","locations":[{"location":"Microtubules","reliability":"Approved"},{"location":"Primary cilium","reliability":"Approved"},{"location":"Centriolar satellite","reliability":"Additional"},{"location":"Basal body","reliability":"Additional"},{"location":"Cytosol","reliability":"Additional"}],"tissue_specificity":"Low tissue specificity","tissue_distribution":"Detected in all","driving_tissues":[],"url":"https://www.proteinatlas.org/search/OCRL"},"hgnc":{"alias_symbol":["OCRL1","Dent-2"],"prev_symbol":[]},"alphafold":{"accession":"Q01968","domains":[{"cath_id":"2.30.29.110","chopping":"11-70_81-119","consensus_level":"high","plddt":81.0314,"start":11,"end":119},{"cath_id":"3.60.10.10","chopping":"236-541","consensus_level":"high","plddt":94.5399,"start":236,"end":541},{"cath_id":"2.60.40.10","chopping":"569-674","consensus_level":"high","plddt":93.0758,"start":569,"end":674},{"cath_id":"1.10.555.10","chopping":"737-897","consensus_level":"high","plddt":92.4397,"start":737,"end":897}],"viewer_url":"https://alphafold.ebi.ac.uk/entry/Q01968","model_url":"https://alphafold.ebi.ac.uk/files/AF-Q01968-F1-model_v6.cif","pae_url":"https://alphafold.ebi.ac.uk/files/AF-Q01968-F1-predicted_aligned_error_v6.png","plddt_mean":82.56},"mouse_models":{"mgi_url":"https://www.informatics.jax.org/marker/summary?nomen=OCRL","jax_strain_url":"https://www.jax.org/strain/search?query=OCRL"},"sequence":{"accession":"Q01968","fasta_url":"https://rest.uniprot.org/uniprotkb/Q01968.fasta","uniprot_url":"https://www.uniprot.org/uniprotkb/Q01968/entry","alphafold_viewer_url":"https://alphafold.ebi.ac.uk/entry/Q01968"}},"corpus_meta":[{"pmid":"15627218","id":"PMC_15627218","title":"Dent Disease with mutations in OCRL1.","date":"2004","source":"American journal of human genetics","url":"https://pubmed.ncbi.nlm.nih.gov/15627218","citation_count":259,"is_preprint":false},{"pmid":"21706022","id":"PMC_21706022","title":"Rab35 GTPase and OCRL phosphatase remodel lipids and F-actin for successful cytokinesis.","date":"2011","source":"Nature cell biology","url":"https://pubmed.ncbi.nlm.nih.gov/21706022","citation_count":241,"is_preprint":false},{"pmid":"17765681","id":"PMC_17765681","title":"A role of the Lowe syndrome protein OCRL in early steps of the endocytic pathway.","date":"2007","source":"Developmental cell","url":"https://pubmed.ncbi.nlm.nih.gov/17765681","citation_count":220,"is_preprint":false},{"pmid":"21971085","id":"PMC_21971085","title":"OCRL controls trafficking through early endosomes via PtdIns4,5P₂-dependent regulation of endosomal actin.","date":"2011","source":"The EMBO 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OCRL protein is associated with lysosomal membranes in proximal tubule cells.\",\n      \"method\": \"In vitro enzymatic assay with substrate preference testing; cell lines from Lowe syndrome patient kidney proximal tubules lacking OCRL protein; lipid quantification showing PI(4,5)P2 accumulation; subcellular fractionation/immunolocalization to lysosomes\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Strong — direct in vitro enzymatic assay establishing substrate specificity plus cell-based functional demonstration with patient-derived cells; replicated by subsequent studies\",\n      \"pmids\": [\"9430698\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2000,\n      \"finding\": \"OCRL1 (Ocrl1) localizes to the trans-Golgi network (TGN) in fibroblasts and kidney epithelial cells, as determined by immunofluorescence, subcellular fractionation, and brefeldin A perturbation assay.\",\n      \"method\": \"Immunofluorescence co-localization with TGN markers, subcellular fractionation, brefeldin A dynamic perturbation assay\",\n      \"journal\": \"The journal of histochemistry and cytochemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — three orthogonal methods in multiple cell types; replicated by many subsequent studies\",\n      \"pmids\": [\"10639484\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2003,\n      \"finding\": \"OCRL1 interacts with activated Rac GTPase via its C-terminal RhoGAP domain both in vitro and by co-immunoprecipitation with endogenous OCRL1. A fraction of endogenous Rac co-localizes with OCRL1 and γ-adaptin in the TGN. The OCRL1 RhoGAP domain shows low Rac GAP activity in vitro and inhibits Rac-GTP-dependent membrane ruffles when expressed in cells.\",\n      \"method\": \"GST pulldown (in vitro binding), co-immunoprecipitation, immunofluorescence co-localization, in vitro GAP activity assay, Swiss 3T3 cell ruffle assay\",\n      \"journal\": \"Human molecular genetics\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — reciprocal Co-IP plus in vitro assay plus functional cell readout, single lab\",\n      \"pmids\": [\"12915445\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2004,\n      \"finding\": \"OCRL localizes to endosomes and Golgi membranes in association with clathrin; it interacts directly with the clathrin terminal domain and clathrin adaptor AP-2, as shown by GST binding assays. Live-cell imaging confirmed dynamic OCRL localization on endosomes.\",\n      \"method\": \"Fluorescence microscopy (fixed and live-cell time-lapse), GST pulldown binding assay with clathrin terminal domain and AP-2\",\n      \"journal\": \"Proceedings of the National Academy of Sciences of the United States of America\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — direct binding assay plus live-cell imaging, single lab\",\n      \"pmids\": [\"15353600\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2005,\n      \"finding\": \"OCRL1 is associated with clathrin-coated transport intermediates between the TGN and endosomes, interacts directly with clathrin heavy chain, and promotes clathrin assembly in vitro. Overexpression of OCRL1 causes redistribution of clathrin and CI-MPR to enlarged endosomal structures defective in retrograde trafficking to the TGN; depletion of OCRL1 causes partial redistribution of CI-MPR to early endosomes.\",\n      \"method\": \"Co-immunoprecipitation, direct clathrin assembly assay in vitro, overexpression and siRNA knockdown with immunofluorescence readout for CI-MPR trafficking\",\n      \"journal\": \"Molecular biology of the cell\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1-2 / Strong — in vitro clathrin assembly assay plus reciprocal Co-IP plus loss/gain-of-function cellular trafficking assays\",\n      \"pmids\": [\"15917292\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2006,\n      \"finding\": \"OCRL1 interacts with multiple Rab GTPases (Rab1, Rab5, Rab6 most strongly). Rab binding is required for targeting OCRL1 to the Golgi and endosomes, as point mutants defective in Rab binding fail to localize to these compartments. In vitro experiments demonstrate that Rab5 and Rab6 directly stimulate the 5-phosphatase activity of OCRL1.\",\n      \"method\": \"Co-immunoprecipitation, pulldown, point mutagenesis with subcellular localization readout, in vitro 5-phosphatase activity assay with Rab proteins\",\n      \"journal\": \"The EMBO journal\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1-2 / Strong — in vitro enzymatic stimulation assay plus mutagenesis plus localization, replicated by structural studies\",\n      \"pmids\": [\"16902405\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2006,\n      \"finding\": \"Missense mutations I751N and A780P in the RhoGAP-homology domain of OCRL1 reduce enzyme (PI(4,5)P2 5-phosphatase) activity by 85-90% without affecting protein expression levels, demonstrating that the RhoGAP domain is important for enzymatic function. Wild-type but not the I751N mutant OCRL1 co-immunoprecipitates with Arf1 and Arf6, indicating the RhoGAP domain mediates interaction with Arf GTPases.\",\n      \"method\": \"In vitro phosphatase activity assay, co-immunoprecipitation with Arf1 and Arf6\",\n      \"journal\": \"Molecular genetics and metabolism\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 1-2 / Moderate — enzymatic assay and Co-IP, single lab\",\n      \"pmids\": [\"16777452\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2007,\n      \"finding\": \"OCRL visits late-stage endocytic clathrin-coated pits and binds the Rab5 effector APPL1 on peripheral early endosomes. The interaction with APPL1 is mediated by the ASH-RhoGAP-like domains of OCRL and is abolished by disease-causing mutations. Crystallographic studies reveal a role of the ASH-RhoGAP-like domains in positioning the phosphatase domain at the membrane interface and show a clathrin box protruding from the RhoGAP-like domain.\",\n      \"method\": \"Co-immunoprecipitation, live-cell imaging, X-ray crystallography, disease-mutation analysis\",\n      \"journal\": \"Developmental cell\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Strong — crystal structure plus Co-IP plus functional mutagenesis in a single study\",\n      \"pmids\": [\"17765681\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2008,\n      \"finding\": \"All known disease-causing missense mutations in the ASH-RhoGAP domains of OCRL abolish the interaction with endocytic adaptor APPL1, which is the only OCRL interaction (among those tested) disrupted by all such mutations. APPL1 and Rab5 independently contribute to recruit OCRL to enlarged endosomes.\",\n      \"method\": \"Co-immunoprecipitation, expression of constitutively active Rab5, disease-mutation analysis\",\n      \"journal\": \"Biochemical and biophysical research communications\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — multiple Co-IP with systematic mutation analysis, single lab\",\n      \"pmids\": [\"18307981\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2008,\n      \"finding\": \"OCRL1 (via its homolog Dd5P4 in Dictyostelium) restricts intracellular growth of Legionella pneumophila. OCRL1 localizes to Legionella-containing vacuoles (LCVs) in macrophages. The N-terminal domain of OCRL1 binds the Legionella effector LpnE. Complementation with catalytically inactive Dd5P4 fails to rescue the phenotype, demonstrating catalytic activity is required.\",\n      \"method\": \"Genetic complementation in Dictyostelium discoideum, fluorescence microscopy localization to LCVs, GST pulldown binding assay with LpnE, catalytically inactive mutant analysis\",\n      \"journal\": \"Cellular microbiology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — genetic complementation with catalytic mutant plus direct binding assay, single lab\",\n      \"pmids\": [\"19021631\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2009,\n      \"finding\": \"OCRL1 isoform a (brain-specific longer isoform) binds clathrin with higher affinity than isoform b and is significantly more enriched in clathrin-coated trafficking intermediates. A second clathrin-binding site was identified in OCRL1. Association with clathrin-coated intermediates requires Rab GTPase-mediated membrane association but not AP2 binding. Expression of the 5-phosphatase-deleted isoform a (but not isoform b equivalent) impairs transferrin endocytosis.\",\n      \"method\": \"Clathrin binding assays, subcellular fractionation, fluorescence microscopy, transferrin endocytosis assay\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — direct binding assay plus functional endocytosis assay, single lab\",\n      \"pmids\": [\"19211563\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2009,\n      \"finding\": \"Lowe syndrome patient fibroblasts lacking OCRL1 display defects in cell migration, spreading, and fluid-phase uptake. These defects are rescued by wild-type OCRL1 but not a phosphatase-deficient mutant, nor by the paralog Inpp5b. OCRL1 variants lacking AP2 or clathrin binding were less able to rescue migration, implicating these interactions in ruffle-mediated membrane remodeling.\",\n      \"method\": \"Cell migration assay, spreading assay, fluid-phase uptake assay, rescue with WT and mutant OCRL1 constructs in patient fibroblasts\",\n      \"journal\": \"Human molecular genetics\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — patient cells plus rescue with multiple mutants, single lab\",\n      \"pmids\": [\"19700499\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2010,\n      \"finding\": \"Two endocytic proteins Ses1 and Ses2 (IPIP27A/B) interact with OCRL via a short phenylalanine and histidine (F&H) motif in the ASH-RhoGAP-like domain, the same site used by APPL1. Ses binding is mutually exclusive with APPL1 binding and is disrupted by the same disease-causing missense mutations.\",\n      \"method\": \"Co-immunoprecipitation, pulldown, competition binding assay, disease-mutation analysis\",\n      \"journal\": \"Proceedings of the National Academy of Sciences of the United States of America\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — reciprocal Co-IP with competition assay and systematic mutation analysis, single lab\",\n      \"pmids\": [\"20133602\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2011,\n      \"finding\": \"Active (GTP-bound) Rab35 directly interacts with OCRL and controls its localization at the intercellular bridge during cytokinesis. Depletion of Rab35 or OCRL inhibits cytokinesis abscission and causes local PI(4,5)P2 and F-actin accumulation in the intercellular bridge. Division defects in Lowe patient cell lines are rescued by low doses of F-actin depolymerization drugs, establishing that OCRL-mediated PI(4,5)P2 hydrolysis is required for F-actin remodeling during abscission.\",\n      \"method\": \"Pulldown with active Rab35, siRNA depletion, live-cell imaging, fluorescence microscopy, pharmacological rescue with F-actin depolymerizing drugs, patient cell lines\",\n      \"journal\": \"Nature cell biology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — direct binding assay plus loss-of-function with defined phenotypic readout plus patient cells plus pharmacological rescue, replicated by Drosophila work\",\n      \"pmids\": [\"21706022\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2011,\n      \"finding\": \"OCRL controls early endosome (EE) function via its 5-phosphatase activity. OCRL depletion impairs recycling of multiple receptors including megalin, causing their retention in engorged EEs. The trafficking defects result from ectopic PI(4,5)P2 accumulation in EEs, which induces N-WASP-dependent increase in endosomal F-actin.\",\n      \"method\": \"siRNA knockdown, receptor recycling assays, lipid imaging, N-WASP manipulation, fluorescence microscopy\",\n      \"journal\": \"The EMBO journal\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — multiple orthogonal methods including receptor trafficking, lipid imaging, and N-WASP epistasis, replicated across labs\",\n      \"pmids\": [\"21971085\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2011,\n      \"finding\": \"OCRL and Inpp5B are recruited to nascent phagosomes as Rab5 effectors via the adaptor protein APPL1. Knockdown of APPL1 or inhibition of Rab5 impairs association of OCRL and Inpp5B with phagosomes and prolongs PI(4,5)P2 and actin presence on phagosomal membranes. APPL1 depletion accentuates Akt activation, linked to increased PI(4,5)P2 available for PI(3,4,5)P3 generation.\",\n      \"method\": \"siRNA knockdown, fluorescence microscopy, lipid imaging on phagosomes, Akt activation assay\",\n      \"journal\": \"Molecular biology of the cell\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — loss-of-function with multiple readouts, single lab\",\n      \"pmids\": [\"22072788\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2011,\n      \"finding\": \"IPIP27A and IPIP27B (Ses1 and Ses2) bind OCRL1 and the related phosphatase Inpp5b via a conserved motif in the C-terminal region of these phosphatases. IPIP27A/B localize to early and recycling endosomes and the TGN, form homo- and heterodimers, and are required for receptor recycling from endosomes both to the TGN and to the plasma membrane.\",\n      \"method\": \"Co-immunoprecipitation, siRNA knockdown with receptor recycling assays, fluorescence microscopy\",\n      \"journal\": \"Molecular biology of the cell\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — Co-IP plus functional recycling assay, single lab\",\n      \"pmids\": [\"21233288\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2011,\n      \"finding\": \"Crystal structure of the Rab-binding domain (RBD/ASH domain) of OCRL1 in complex with Rab8a reveals that the Rab-binding interface consists mainly of the IgG-like β-strand structure of the ASPM-SPD-2-Hydin domain plus one α-helix, distinct from other Rab effectors. Kinetic analysis showed binding to Rab1b, Rab5a, Rab6a, and Rab8a. Disease-causing mutations in the RBD affect Rab binding.\",\n      \"method\": \"X-ray crystallography, kinetic binding analysis (surface plasmon resonance), disease-mutation analysis\",\n      \"journal\": \"The EMBO journal\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Strong — crystal structure plus kinetic binding characterization plus disease-mutation functional annotation\",\n      \"pmids\": [\"21378754\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2011,\n      \"finding\": \"X-ray crystallography of the OCRL RhoGAP domain identified the F&H motif binding site. Disease-associated missense mutations in the ASH-RhoGAP domain disrupt F&H binding indirectly by destabilizing the RhoGAP fold. A disease mutation that does not perturb F&H binding and ASH-RhoGAP stability instead disrupts the interaction of OCRL with Rab5.\",\n      \"method\": \"X-ray crystallography, binding assays, mutagenesis with functional analysis of APPL1/Ses binding and Rab5 binding\",\n      \"journal\": \"Nature structural & molecular biology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Strong — crystal structure plus mutagenesis plus binding assays distinguishing two classes of disease mutations\",\n      \"pmids\": [\"21666675\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2012,\n      \"finding\": \"OCRL localizes to the primary cilium of retinal pigment epithelial cells, fibroblasts, and kidney tubular cells. Lowe syndrome-associated mutations in OCRL result in shortened cilia, rescued by wild-type OCRL re-expression. In vivo, knockdown of ocrl in zebrafish causes defective cilia formation in Kupffer's vesicles and cilia-dependent phenotypes.\",\n      \"method\": \"Fluorescence microscopy of primary cilia, rescue experiments with WT OCRL, zebrafish morpholino knockdown\",\n      \"journal\": \"Human molecular genetics\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — direct localization plus rescue plus in vivo model, single lab\",\n      \"pmids\": [\"22543976\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2012,\n      \"finding\": \"OCRL1 is required for primary cilia assembly; patient cells and OCRL1 knockdown cells show defects in cilia assembly rescued by WT OCRL1. OCRL1 is involved in protein trafficking to the primary cilia in a Rab8- and IPIP27/Ses-dependent manner.\",\n      \"method\": \"siRNA knockdown, rescue with WT OCRL1, patient cell lines, zebrafish model, fluorescence microscopy, trafficking assays\",\n      \"journal\": \"Human molecular genetics\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — patient cells plus rescue plus in vivo zebrafish model, single lab\",\n      \"pmids\": [\"22228094\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2012,\n      \"finding\": \"OCRL loss in Lowe syndrome patient fibroblasts impairs clathrin-mediated endocytosis, causing accumulation of clathrin-coated vesicles and U-shaped clathrin-coated pits. Endocytic vesicles that fail to shed their coat nucleate actin comets. SNX9, which couples late-stage endocytic pits to actin polymerization, binds OCRL directly and remains associated with uncoated vesicles in patient cells, establishing OCRL as an uncoating factor.\",\n      \"method\": \"Patient fibroblast analysis, electron microscopy, direct pulldown of SNX9-OCRL, fluorescence microscopy of coated vesicles and actin comets\",\n      \"journal\": \"eLife\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — patient cells plus direct binding assay plus ultrastructural analysis, multiple orthogonal methods\",\n      \"pmids\": [\"25107275\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2012,\n      \"finding\": \"OCRL depletion in HeLa cells decreases endosome-to-TGN transport of the mannose 6-phosphate receptor (MPR), leading to its accumulation in enlarged retromer-positive endosomes and higher surface levels of MPR. Wild-type OCRL rescues MPR accumulation in an activity-dependent manner. OCRL depletion increases inactive phospho-cofilin and reduces active Rac1, while increasing active RhoA; overexpression of Rac1 rescues both cofilin phosphorylation and MPR accumulation, establishing a PI(4,5)P2–Rac1–cofilin signaling module downstream of OCRL.\",\n      \"method\": \"siRNA knockdown, fluorescence microscopy, receptor trafficking assays, GTPase activation assays (pulldown), cofilin phosphorylation immunoblotting, rescue by Rac1 overexpression\",\n      \"journal\": \"Human molecular genetics\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — multiple pathway readouts plus rescue epistasis, single lab\",\n      \"pmids\": [\"22907655\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2012,\n      \"finding\": \"OCRL controls PI(4,5)P2 levels at the surface of endosomes during cytokinesis, restricting PI(4,5)P2 to the cell cortex. Drosophila dOCRL (ortholog of human OCRL1) is essential for cytokinesis, acting to dephosphorylate PI(4,5)P2 at endosomal surfaces.\",\n      \"method\": \"Drosophila genetic loss-of-function, live-cell imaging, PI(4,5)P2 reporters\",\n      \"journal\": \"Communicative & integrative biology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — genetic loss-of-function in a model organism with defined molecular readout, single lab\",\n      \"pmids\": [\"22896796\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2012,\n      \"finding\": \"OCRL suppresses the intestinal calcium channel TRPV6 via two separate mechanisms: (1) the PI(4,5)P2 5-phosphatase domain suppresses TRPV6-mediated Ca2+ transport by reducing PI(4,5)P2 levels without affecting TRPV6 surface abundance; (2) the Rab-binding domain regulates forward trafficking of TRPV6 to the cell surface. Dent-causing OCRL mutations alleviate inhibition of TRPV6-mediated Ca2+ transport.\",\n      \"method\": \"Xenopus oocyte expression system, Ca2+ uptake assays, cell surface quantification, antisense OCRL knockdown in Xenopus, Dent-mutation analysis\",\n      \"journal\": \"American journal of physiology. Cell physiology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 1-2 / Moderate — functional assay in heterologous expression system with domain dissection and loss-of-function, single lab\",\n      \"pmids\": [\"22378746\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2012,\n      \"finding\": \"Through its phosphatase activity, OCRL restricts Listeria monocytogenes invasion by modulating PI(4,5)P2 and PI(3,4,5)P3 levels and actin dynamics at bacterial internalization foci. OCRL accumulates at invasion foci coincident with actin depolymerization; catalytically dead OCRL fails to rescue the phenotype.\",\n      \"method\": \"siRNA knockdown, live-cell imaging, fluorescence microscopy, rescue with enzymatically active vs. dead OCRL-a\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — loss-of-function plus catalytic dead rescue, single lab\",\n      \"pmids\": [\"22351770\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2012,\n      \"finding\": \"Bcl10 delivers the OCRL phosphatase to phagocytic cups via a complex with clathrin adaptors AP1 and EpsinR. OCRL locally regulates PI(4,5)P2 and F-actin turnover required for phagosome closure.\",\n      \"method\": \"Co-immunoprecipitation, siRNA knockdown, fluorescence microscopy, phagocytosis assays in human macrophages\",\n      \"journal\": \"Developmental cell\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — Co-IP complex identification plus loss-of-function with defined phagocytic readout, single lab\",\n      \"pmids\": [\"23153494\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2015,\n      \"finding\": \"Rab35 GTPase acts as a switch for OCRL recruitment on newborn endosomes immediately after scission of clathrin-coated vesicles (CCVs). Rab35 loading on CCVs follows DENND1A recruitment and EPI64B disappearance. Depletion of Rab35 or OCRL causes retention of CI-MPR in peripheral clathrin-positive endosomes with abnormal PI(4,5)P2 and actin-binding proteins.\",\n      \"method\": \"Live-cell imaging, siRNA knockdown, direct binding assays, fluorescence microscopy of endogenous receptors and lipids\",\n      \"journal\": \"Current biology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — direct binding plus loss-of-function for both proteins with defined trafficking readout plus mechanistic dissection of Rab35 GEF/GAP cycle, single lab with multiple orthogonal approaches\",\n      \"pmids\": [\"26725203\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2015,\n      \"finding\": \"OCRL1 is required for endocytosis in the zebrafish pronephric tubule in vivo; OCRL1 deficiency causes reduced megalin levels and accumulation in endocytic compartments, reduced numbers of early endosomes, and enlarged vacuolar endosomes. Catalytic activity of OCRL1 is required for renal tubular endocytosis, and the endocytic defect is rescued by suppression of PIP5K.\",\n      \"method\": \"Zebrafish ocrl1 mutant model, fluorescence/electron microscopy, endocytosis assays, rescue by PIP5K suppression\",\n      \"journal\": \"PLoS genetics\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — in vivo genetic model with defined endocytic readout plus catalytic mutant analysis plus epistasis via PIP5K suppression\",\n      \"pmids\": [\"25838181\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2015,\n      \"finding\": \"OCRL1 interacts with F-BAR protein pacsin 2 via IPIP27A. OCRL1 and IPIP27A localize to MPR-containing trafficking intermediates; loss of either protein impairs MPR carrier biogenesis at TGN and endosomes. OCRL1 5-phosphatase activity (which is stimulated by membrane curvature and further by IPIP27A-mediated engagement with pacsin 2) promotes scission of MPR-containing carriers.\",\n      \"method\": \"Co-immunoprecipitation, siRNA knockdown, live-cell imaging, MPR trafficking assay, in vitro phosphatase activity assay with membrane curvature\",\n      \"journal\": \"Molecular biology of the cell\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — Co-IP plus functional trafficking assay plus enzymatic assay with curvature sensitivity, single lab\",\n      \"pmids\": [\"26510499\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2015,\n      \"finding\": \"OCRL1 acts as a RacGAP in chondrocytes. Overexpression of OCRL1 inhibits Rac1 activity and chondrocyte hypertrophy; knockdown elevates Rac1 activity and promotes hypertrophy/mineralization. The GAP activity requires the GAP domain. Intraarticular injection of OCRL1-encoding lentivirus protects against cartilage destruction in a mouse OA model.\",\n      \"method\": \"Rac1 activity pulldown assay, lentiviral overexpression and knockdown, alkaline phosphatase staining, mouse OA intraarticular injection model\",\n      \"journal\": \"Arthritis & rheumatology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — direct GTPase activity assay plus domain mutant analysis plus in vivo model, single lab\",\n      \"pmids\": [\"25917196\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2016,\n      \"finding\": \"OCRL plays a key role in a lysosomal response to autophagosome-lysosome fusion. Mitochondrial DNA delivered by autophagosomes activates TLR9 as cargo/receptor. A local, transient increase in PI(4,5)P2 is confined by OCRL. OCRL depletion causes accumulation of lysosomal PI(4,5)P2, which inhibits the calcium channel mucolipin-1, blocking autophagosome-lysosome fusion. Boosting mucolipin-1 activity with agonists restores autophagic flux in Lowe syndrome patient cells.\",\n      \"method\": \"siRNA knockdown, Lowe patient cell lines, PI(4,5)P2 and mucolipin-1 functional assays, TLR9/mtDNA identification as cargo/receptor, pharmacological rescue\",\n      \"journal\": \"Nature cell biology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — multiple orthogonal methods including molecular identification of cargo/receptor, lipid imaging, pharmacological rescue in patient cells, single high-rigor study\",\n      \"pmids\": [\"27398910\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2017,\n      \"finding\": \"OCRL loss increases PI(4,5)P2 and decreases PI4P in primary cilia, with PI(4,5)P2 build-up particularly at the transition zone. This is reversed by reintroduction of OCRL. In Lowe syndrome mouse model MEFs, accumulation of sonic hedgehog in response to hedgehog agonist is decreased.\",\n      \"method\": \"Fluorescence microscopy with PI(4,5)P2 and PI4P reporters in patient fibroblasts and MEFs from Lowe mouse model; rescue with WT OCRL; Hedgehog pathway readout\",\n      \"journal\": \"Journal of cell science\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — direct lipid measurement in cilia plus rescue plus signaling readout, single lab\",\n      \"pmids\": [\"28871046\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2019,\n      \"finding\": \"In a humanized mouse model (OcrlY/- with human INPP5B rescue of Inpp5b lethality), OCRL deficiency causes massive urinary loss of low-molecular-weight proteins and albumin due to selective impairment of receptor-mediated endocytosis in proximal tubule cells. PI(4,5)P2 accumulation in endolysosomes drives local F-actin hyper-polymerization, impairing trafficking of the LRP2 endocytic receptor. OCRL deficiency also disrupts lysosomal dynamics and proteolytic activity.\",\n      \"method\": \"Humanized mouse model, primary mPTC culture, urine analysis, fluorescence microscopy, F-actin quantification, receptor trafficking assay for LRP2\",\n      \"journal\": \"Human molecular genetics\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — in vivo mouse model plus primary cell culture with mechanistic dissection of PI(4,5)P2–F-actin–LRP2 axis, multiple orthogonal readouts\",\n      \"pmids\": [\"30590522\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2021,\n      \"finding\": \"Rab5 recruits OCRL and Inpp5b to macropinosomes via APPL1, downstream of membrane ruffling. This recruitment mediates PI(4,5)P2 removal required for macropinosome sealing/scission. Knockdown of OCRL and Inpp5b, or APPL1, prevents macropinosome closure without affecting ruffling.\",\n      \"method\": \"siRNA knockdown, dominant-negative Rab5, fluorescence microscopy, PI(4,5)P2 imaging, macropinocytosis assay\",\n      \"journal\": \"Journal of cell science\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — loss-of-function with defined readout and pathway dissection, single lab\",\n      \"pmids\": [\"33722976\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2021,\n      \"finding\": \"Legionella effector SdhA binds the OCRL ASH domain and blocks OCRL's interactions with Rab GTPases (without directly altering its catalytic 5-phosphatase activity), thereby hijacking OCRL function to maintain vacuole integrity. OCRL depletion enhances vacuole integrity and intracellular growth of a sdhA mutant. Overexpressed SdhA causes endosomal PI(4,5)P2 accumulation and interferes with endosomal trafficking.\",\n      \"method\": \"Co-immunoprecipitation, OCRL knockdown, fluorescence microscopy of vacuole integrity and endosomal markers, in vitro binding assay mapping interaction to ASH domain, 5-phosphatase activity assay\",\n      \"journal\": \"Cell reports\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1-2 / Strong — direct binding assay with domain mapping plus activity assay plus genetic loss-of-function with defined vacuole phenotype, multiple orthogonal methods\",\n      \"pmids\": [\"34731604\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2021,\n      \"finding\": \"OCRL deficiency in megakaryocytes and platelets causes defective actomyosin cytoskeleton reorganization: reduced Rac1 activity, elevated active RhoA, increased phosphorylated (inactive) myosin light chain (P-MLC), resulting in deficient proplatelet extension and impaired platelet spreading and clot retraction. OCRL depletion with siOCRL in control MKs reproduces the proplatelet extension defect.\",\n      \"method\": \"Case-control study on patient platelets/MKs, GTPase activation pulldown assay, MLC phosphorylation immunoblotting, siRNA knockdown in MKs, flow-based thrombus formation assay\",\n      \"journal\": \"British journal of haematology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — patient cells plus siRNA validation plus multiple functional readouts, single lab\",\n      \"pmids\": [\"33528045\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2022,\n      \"finding\": \"A novel OCRL protein isoform translated from exon 8 (80 kDa) retains equivalent 5-phosphatase enzyme activity to full-length OCRL. Truncating mutations in exons 1–7 (Dent disease-2) produce this shorter functional isoform with >50% activity, whereas truncating mutations in exons 8–24 (Lowe syndrome) produce no detectable protein and <20% activity, explaining the phenotypic difference between the two diseases.\",\n      \"method\": \"mRNA cloning from patient urine-derived cells, in vitro protein expression analysis, 5-phosphatase activity assay, transfection into HeLa cells\",\n      \"journal\": \"Nephrology, dialysis, transplantation\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Strong — direct enzymatic activity assay plus in vitro protein expression with multiple disease variants establishing molecular basis for genotype-phenotype correlation\",\n      \"pmids\": [\"34586410\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 1998,\n      \"finding\": \"Targeted disruption of mouse Ocrl1 produces no phenotype (no cataracts, renal Fanconi syndrome, or neurological abnormalities), but double knockout of Ocrl1 and Inpp5b results in embryonic lethality with no live-born mice, demonstrating overlapping essential functions of the two paralogs in mice.\",\n      \"method\": \"Targeted gene disruption in mice (Ocrl1-/- and Inpp5b-/-), double mutant crosses, embryo analysis\",\n      \"journal\": \"The Journal of clinical investigation\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — genetic epistasis by double knockout; embryonic lethality as unambiguous readout; replicated by subsequent studies\",\n      \"pmids\": [\"9593760\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2016,\n      \"finding\": \"Kidney tubule-specific inactivation of Inpp5b on a global Ocrl-knockout mouse background results in low molecular weight proteinuria, phosphaturia, acidemia, and striking impairment of clathrin-dependent and -independent endocytosis in proximal tubules, phenocopying Dent disease caused by mutations in ClC-5.\",\n      \"method\": \"Conditional knockout mouse model (tubule-specific Inpp5b deletion on global Ocrl-/- background), urine analysis, electron microscopy of proximal tubules, endocytosis assays\",\n      \"journal\": \"Journal of the American Society of Nephrology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — conditional double-knockout mouse with organ-specific readout and defined endocytic phenotype\",\n      \"pmids\": [\"27895154\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2005,\n      \"finding\": \"Upon EGF-induced Rac activation in COS-7 cells, a fraction of OCRL1 translocates from the TGN to plasma membrane ruffles. In Lowe patient fibroblasts, PI(4,5)P2 accumulates strikingly in PDGF-induced ruffles compared with controls, indicating OCRL1 is active as a PI(4,5)P2 5-phosphatase in Rac-induced membrane ruffles.\",\n      \"method\": \"Fluorescence microscopy in live/fixed cells, GFP-PH domain PI(4,5)P2 reporter, patient fibroblast vs control comparison, growth factor stimulation\",\n      \"journal\": \"Human molecular genetics\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — direct localization experiment with functional consequence (lipid accumulation in patient cells), single lab\",\n      \"pmids\": [\"15829501\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2010,\n      \"finding\": \"Rab31 interacts with OCRL-1 in oligodendrocytes (yeast two-hybrid, GST pulldown, co-immunoprecipitation) and recruits OCRL-1 to TGN domains where MPR-containing carrier formation occurs. siRNA depletion of Rab31 markedly decreases OCRL-1 levels in the TGN and endosomes. MPR is sorted to OCRL-1-containing carriers.\",\n      \"method\": \"Yeast two-hybrid, GST pulldown, co-immunoprecipitation, siRNA knockdown, fluorescence microscopy\",\n      \"journal\": \"Journal of neuroscience research\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — three binding assays plus functional depletion, single lab\",\n      \"pmids\": [\"19795375\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2011,\n      \"finding\": \"OCRL1 localizes to intercellular junctions at early stages of their formation, co-localizing with adherens and tight junctional components and forming complexes with α-catenin and ZO-1/2/3. Depletion of OCRL1 in epithelial sheets inhibits maturation, polarity, and proliferation; this effect requires the 5-phosphatase domain and is rescued by re-expressed OCRL1. In 3D cultures, OCRL1-depleted cells fail to form a central lumen and show incorrect ZO-1 distribution.\",\n      \"method\": \"Co-immunoprecipitation with junctional proteins, siRNA knockdown, rescue with WT and phosphatase-dead OCRL1, fluorescence microscopy in 2D and 3D culture\",\n      \"journal\": \"PloS one\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — Co-IP plus knockdown/rescue with domain-function analysis, single lab\",\n      \"pmids\": [\"21901156\"],\n      \"is_preprint\": false\n    }\n  ],\n  \"current_model\": \"OCRL is an X-linked inositol polyphosphate 5-phosphatase that preferentially dephosphorylates PI(4,5)P2 (and to a lesser extent PI(3,4,5)P3) at the trans-Golgi network, endosomes, clathrin-coated pits/vesicles, phagosomes, macropinosomes, and the primary cilium; it is recruited to these membranes by multiple Rab GTPases (especially Rab5, Rab35, Rab8) whose binding to its ASH-RhoGAP domain simultaneously stimulates catalytic activity, while endocytic adaptors APPL1, Ses1/2 (IPIP27A/B), and SNX9 further anchor OCRL at specific endocytic compartments; by locally reducing PI(4,5)P2, OCRL controls F-actin remodeling (via N-WASP and cofilin/Rac1 pathways), clathrin coat shedding from endocytic vesicles, cargo recycling (including megalin/LRP2) from early endosomes to the plasma membrane and TGN, cytokinesis abscission, ciliogenesis, and autophagosome–lysosome fusion, with loss of OCRL function causing PI(4,5)P2 accumulation at endolysosomes, aberrant F-actin polymerization, and defective membrane trafficking that underlies the renal, ocular, and neurological phenotypes of Lowe syndrome and Dent disease 2.\"\n}\n```","stage2_raw":"{\n  \"mechanistic_narrative\": \"OCRL is an X-linked inositol polyphosphate 5-phosphatase that preferentially hydrolyzes PI(4,5)P2 and is the major PI(4,5)P2 5-phosphatase of kidney proximal tubule cells, where its loss causes PI(4,5)P2 accumulation [#0]. The enzyme operates across the secretory and endocytic system — the trans-Golgi network, clathrin-coated transport intermediates, early and recycling endosomes, phagosomes, macropinosomes, and the primary cilium — by being recruited to specific membranes through its ASH-RhoGAP module [#1, #3, #4, #19]. Recruitment and catalysis are coupled: multiple Rab GTPases (Rab1, Rab5, Rab6, Rab8, Rab35) bind the ASH (Rab-binding) domain through an IgG-like β-strand interface and directly stimulate 5-phosphatase activity, so that membrane targeting and enzymatic action are activated together [#5, #6, #17, #27]. A conserved F&H motif in the same module engages the endocytic adaptors APPL1 and Ses1/2 (IPIP27A/B) in a mutually exclusive manner, and these interactions are uniformly abolished by disease-causing missense mutations, which act either by destabilizing the RhoGAP fold or by disrupting Rab5 binding [#7, #12, #18]. By locally removing PI(4,5)P2, OCRL drives clathrin coat shedding and uncoating via SNX9, restrains N-WASP- and Rac1/cofilin-dependent F-actin polymerization, and promotes carrier scission and receptor recycling, including endosome-to-TGN transport of the mannose-6-phosphate receptor and recycling of the endocytic receptor megalin/LRP2 [#14, #21, #22, #27, #33]. The same lipid-control function underlies abscission during cytokinesis, ciliogenesis and ciliary lipid identity, macropinosome and phagosome sealing, and a lysosomal PI(4,5)P2–mucolipin-1 signal that permits autophagosome–lysosome fusion [#13, #20, #31, #32, #34]. OCRL and its paralog INPP5B have overlapping essential functions: single Ocrl loss is tolerated in mice while combined loss is embryonic-lethal, and proximal-tubule endocytic failure with PI(4,5)P2-driven F-actin hyperpolymerization underlies the renal phenotype [#33, #38, #39]. Loss-of-function mutations in OCRL cause Lowe syndrome and Dent disease 2, with the milder Dent-2 phenotype explained by an exon-8-derived 80 kDa isoform that retains 5-phosphatase activity when N-terminal truncations spare it [#37].\",\n  \"teleology\": [\n    {\n      \"year\": 1998,\n      \"claim\": \"Establishing OCRL's biochemical identity answered what the gene product does enzymatically and linked its loss to a defined lipid imbalance in the affected tissue.\",\n      \"evidence\": \"In vitro substrate-preference enzymatic assays plus PI(4,5)P2 quantification in Lowe patient proximal-tubule cells lacking OCRL\",\n      \"pmids\": [\"9430698\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Lysosomal association reported but membrane-recruitment mechanism unknown at this stage\", \"Did not address how a single enzyme deficiency produces multi-organ disease\"]\n    },\n    {\n      \"year\": 1998,\n      \"claim\": \"Mouse genetics resolved why OCRL loss is far milder in mice than humans, revealing functional redundancy with the paralog INPP5B.\",\n      \"evidence\": \"Targeted Ocrl1 and Inpp5b single and double knockouts in mice\",\n      \"pmids\": [\"9593760\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Molecular basis of paralog redundancy not defined\", \"Did not explain the species-specific phenotypic divergence mechanistically\"]\n    },\n    {\n      \"year\": 2000,\n      \"claim\": \"Localizing OCRL to the TGN placed the enzyme at a specific membrane trafficking station rather than diffusely at lysosomes.\",\n      \"evidence\": \"Immunofluorescence, subcellular fractionation, and brefeldin A perturbation in fibroblasts and kidney epithelial cells\",\n      \"pmids\": [\"10639484\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Recruitment determinants not identified\", \"Functional consequence of TGN localization untested\"]\n    },\n    {\n      \"year\": 2004,\n      \"claim\": \"Linking OCRL physically to clathrin and AP-2 connected the phosphatase to the clathrin coat machinery and to dynamic endosomal trafficking.\",\n      \"evidence\": \"GST binding assays with clathrin terminal domain and AP-2 plus live-cell imaging on endosomes; clathrin assembly assay and CI-MPR trafficking readouts\",\n      \"pmids\": [\"15353600\", \"15917292\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Whether clathrin binding precedes or follows membrane targeting unresolved\", \"Catalytic versus scaffolding contribution to retrograde transport not separated\"]\n    },\n    {\n      \"year\": 2006,\n      \"claim\": \"Discovery that Rab GTPases both target OCRL and stimulate its activity unified membrane recruitment with catalytic activation into a single regulatory logic.\",\n      \"evidence\": \"Co-IP and pulldown with Rab1/5/6, point mutants defective in Rab binding, and in vitro 5-phosphatase stimulation assays; RhoGAP-domain disease mutants reducing activity 85-90%\",\n      \"pmids\": [\"16902405\", \"16777452\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Structural basis of Rab-stimulated activation not yet defined\", \"Why the RhoGAP domain controls enzymatic activity unclear at this stage\"]\n    },\n    {\n      \"year\": 2010,\n      \"claim\": \"Identifying the F&H motif and its adaptors (APPL1, Ses1/2) defined how OCRL is anchored to distinct endocytic compartments and why all ASH-RhoGAP disease mutations converge on lost adaptor binding.\",\n      \"evidence\": \"Co-IP, competition binding assays, and systematic disease-mutation analysis of APPL1 and Ses1/2 (IPIP27A/B) binding\",\n      \"pmids\": [\"18307981\", \"20133602\", \"21233288\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"What determines APPL1- versus Ses-bound pools in cells not established\", \"Single-lab Co-IP evidence for the mutual exclusivity model\"]\n    },\n    {\n      \"year\": 2011,\n      \"claim\": \"Crystal structures of the Rab-binding and RhoGAP domains explained membrane positioning and partitioned disease mutations into mechanistically distinct classes.\",\n      \"evidence\": \"X-ray crystallography of the ASH domain–Rab8a complex and of the RhoGAP/F&H site, with SPR kinetics and disease-mutation mapping\",\n      \"pmids\": [\"21378754\", \"21666675\", \"17765681\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Full-length OCRL architecture and how all modules coordinate on a membrane not resolved\", \"Conformational basis of Rab-stimulated catalysis not directly visualized\"]\n    },\n    {\n      \"year\": 2011,\n      \"claim\": \"Connecting OCRL to early-endosome recycling, cytokinesis abscission, and phagosome maturation defined the downstream consequence of local PI(4,5)P2 removal: control of F-actin via N-WASP and Rab35-dependent recruitment.\",\n      \"evidence\": \"siRNA depletion with receptor recycling, lipid imaging, N-WASP epistasis, Rab35 pulldown, patient cells, and pharmacological F-actin rescue\",\n      \"pmids\": [\"21971085\", \"21706022\", \"22072788\", \"22907655\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"How distinct Rab/adaptor combinations specify each compartment not fully mapped\", \"Relative contribution of actin regulators (N-WASP, cofilin/Rac1) across compartments unclear\"]\n    },\n    {\n      \"year\": 2012,\n      \"claim\": \"Establishing OCRL's role in ciliogenesis and ciliary lipid identity extended its trafficking function to a structure central to the renal and developmental phenotypes.\",\n      \"evidence\": \"Cilium localization, patient/knockdown defects rescued by WT OCRL, Rab8/IPIP27-dependent ciliary trafficking, lipid reporters, and zebrafish knockdown\",\n      \"pmids\": [\"22543976\", \"22228094\", \"28871046\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Direct link between ciliary PI(4,5)P2 control and disease phenotypes not proven\", \"Single-lab in vivo evidence for ciliary trafficking model\"]\n    },\n    {\n      \"year\": 2014,\n      \"claim\": \"Identifying OCRL as a clathrin uncoating factor recruited via SNX9 explained how its loss produces persistent coated vesicles and ectopic actin comets.\",\n      \"evidence\": \"Lowe patient fibroblasts, electron microscopy, and direct SNX9-OCRL pulldown\",\n      \"pmids\": [\"25107275\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Order of SNX9 binding relative to Rab35 loading not resolved\", \"Whether uncoating is driven by lipid hydrolysis or scaffolding not fully separated\"]\n    },\n    {\n      \"year\": 2016,\n      \"claim\": \"Linking OCRL to a lysosomal PI(4,5)P2–mucolipin-1 axis showed how the enzyme governs autophagosome–lysosome fusion and offered a pharmacological correction in patient cells.\",\n      \"evidence\": \"siRNA, patient cells, mucolipin-1 functional assays, mtDNA/TLR9 cargo identification, and agonist rescue\",\n      \"pmids\": [\"27398910\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"How transient PI(4,5)P2 increase is generated and confined not detailed\", \"Single high-rigor study\"]\n    },\n    {\n      \"year\": 2019,\n      \"claim\": \"A humanized mouse model defined the in vivo proximal-tubule mechanism: endolysosomal PI(4,5)P2 accumulation drives F-actin hyperpolymerization that blocks LRP2/megalin trafficking, causing low-molecular-weight proteinuria.\",\n      \"evidence\": \"OcrlY/- humanized mouse with human INPP5B rescue, primary mPTC culture, F-actin quantification, urine analysis, and LRP2 trafficking assays\",\n      \"pmids\": [\"30590522\", \"25838181\", \"27895154\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Therapeutic correction of the renal phenotype in vivo not demonstrated\", \"Why other organs are spared in mice while affected in humans unresolved\"]\n    },\n    {\n      \"year\": 2022,\n      \"claim\": \"Discovery of an exon-8-derived 80 kDa active isoform provided the molecular basis for the genotype-phenotype split between Dent disease 2 and Lowe syndrome.\",\n      \"evidence\": \"mRNA cloning from patient cells, in vitro expression, and 5-phosphatase activity assays across disease variants\",\n      \"pmids\": [\"34586410\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Tissue distribution and physiological role of the short isoform not established\", \"Why residual activity protects against ocular/neurological but not all renal features unclear\"]\n    },\n    {\n      \"year\": null,\n      \"claim\": \"How OCRL's full-length modular architecture coordinates Rab binding, adaptor selection, membrane curvature sensing, and catalytic activation in a single integrated cycle on a membrane remains unresolved.\",\n      \"evidence\": \"\",\n      \"pmids\": [],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"No full-length structure on a membrane\", \"Mechanism by which the RhoGAP/ASH module allosterically controls the phosphatase domain not defined\", \"Compartment-specific partner choice rules not established\"]\n    }\n  ],\n  \"mechanism_profile\": {\n    \"molecular_activity\": [\n      {\"term_id\": \"GO:0016787\", \"supporting_discovery_ids\": [0, 6, 37]},\n      {\"term_id\": \"GO:0098772\", \"supporting_discovery_ids\": [2, 30]},\n      {\"term_id\": \"GO:0060090\", \"supporting_discovery_ids\": [7, 12, 21]}\n    ],\n    \"localization\": [\n      {\"term_id\": \"GO:0005794\", \"supporting_discovery_ids\": [1, 3, 29]},\n      {\"term_id\": \"GO:0005768\", \"supporting_discovery_ids\": [3, 7, 14, 27]},\n      {\"term_id\": \"GO:0005764\", \"supporting_discovery_ids\": [0, 31]},\n      {\"term_id\": \"GO:0005929\", \"supporting_discovery_ids\": [19, 20, 32]},\n      {\"term_id\": \"GO:0005886\", \"supporting_discovery_ids\": [40]},\n      {\"term_id\": \"GO:0031410\", \"supporting_discovery_ids\": [4, 10, 21]}\n    ],\n    \"pathway\": [\n      {\"term_id\": \"R-HSA-5653656\", \"supporting_discovery_ids\": [4, 14, 21, 27]},\n      {\"term_id\": \"R-HSA-1640170\", \"supporting_discovery_ids\": [13, 23]},\n      {\"term_id\": \"R-HSA-9612973\", \"supporting_discovery_ids\": [31]},\n      {\"term_id\": \"R-HSA-9609507\", \"supporting_discovery_ids\": [16, 20, 29]},\n      {\"term_id\": \"R-HSA-1643685\", \"supporting_discovery_ids\": [33, 37]}\n    ],\n    \"complexes\": [],\n    \"partners\": [\"APPL1\", \"IPIP27A/B (Ses1/2)\", \"Rab5\", \"Rab35\", \"Rab8\", \"SNX9\", \"Clathrin\", \"Rab6\"],\n    \"other_free_text\": []\n  }\n}","audit_flag":null,"evaluation":{"pairwise":"win","faith_supported":8,"faith_total":8,"faith_pct":100.0}}