{"gene":"PHLDB2","run_date":"2026-04-28T19:45:44","timeline":{"discoveries":[{"year":2002,"finding":"LL5β (PHLDB2) binds phosphatidylinositol (3,4,5)-trisphosphate (PtdIns(3,4,5)P3) selectively via its C-terminal PH domain in vitro, and its subcellular localization is dynamically regulated by PI3K activity: at low PtdIns(3,4,5)P3 levels (wortmannin/LY294002 treatment or PI3K-deficient PDGFR mutants), LL5β redistributes to an intracellular vesicle population, while elevated PtdIns(3,4,5)P3 drives cytoplasmic and plasma membrane localization. LL5β also binds the cytoskeletal adaptor γ-filamin tightly in vitro and in vivo in a PI3K-independent manner.","method":"In vitro PtdIns(3,4,5)P3 binding assay, PH domain mutagenesis, pharmacological PI3K inhibition, PI3K-deficient PDGFR mutants, co-immunoprecipitation, co-localization imaging","journal":"The Journal of biological chemistry","confidence":"High","confidence_rationale":"Tier 1 — in vitro binding assay with mutagenesis, replicated with multiple orthogonal methods in a single study","pmids":["12376540"],"is_preprint":false},{"year":2005,"finding":"LL5β (PHLDB2) is enriched at the postsynaptic membrane of the neuromuscular junction (NMJ), localizes to the cytoplasmic face of the postsynaptic membrane bordering regions of highest AChR density, binds phosphoinositides and filamin, and is required for AChR aggregation in myotubes (perturbation of LL5β expression inhibits AChR aggregation).","method":"Microarray identification, subcellular fractionation/localization, filamin binding assay, siRNA/dominant-negative perturbation with AChR aggregation readout","journal":"The Journal of cell biology","confidence":"High","confidence_rationale":"Tier 2 — reciprocal binding assays, loss-of-function with specific phenotypic readout, localization tied to function","pmids":["15851520"],"is_preprint":false},{"year":2006,"finding":"LL5β (PHLDB2) forms a cortical complex with ELKS and CLASPs at the cell cortex and leading edge. LL5β is required for cortical CLASP accumulation and microtubule stabilization at the cortex of HeLa cells. LL5β is a PIP3-binding protein whose cortical recruitment is regulated by PI3K activity but does not require intact microtubules. Cortical LL5β/ELKS clusters do not overlap with focal adhesions but form in their vicinity and can affect focal adhesion size.","method":"Mass spectrometry-based identification of partners, co-immunoprecipitation, RNAi knockdown, live-cell imaging, PI3K inhibition","journal":"Developmental cell","confidence":"High","confidence_rationale":"Tier 2 — MS-identified complex, reciprocal co-IP, clean RNAi with defined cellular phenotypes; highly cited foundational study","pmids":["16824950"],"is_preprint":false},{"year":2006,"finding":"An N-terminal region of LL5β mediates binding to the C-terminus of filamins (including filamin C). Under very low PI3K activity, this N-terminal region plus an additional domain localizes the LL5β–filamin complex to punctate structures also decorated by L-FILIP. PtdIns(3,4,5)P3 binding to the C-terminal PH domain of LL5β prevents localization to these structures under high PI3K activity.","method":"Domain mapping/mutagenesis, co-immunoprecipitation, subcellular localization imaging with PI3K inhibition","journal":"Cellular signalling","confidence":"Medium","confidence_rationale":"Tier 2 — domain-mapping with mutagenesis, localization studies; single lab","pmids":["17174070"],"is_preprint":false},{"year":2010,"finding":"PtdIns(3,4,5)P3-localized LL5β recruits Filamin A and SHIP2 (via Filamin A) to the plasma membrane at sites of PIP3 accumulation, promoting lamellipodium formation. Depletion of either Filamin A or LL5β, or expression of a PtdIns(3,4,5)P3-binding-deficient LL5β mutant, inhibits EGF-induced large lamellipodium formation. Co-recruited SHIP2 dephosphorylates PtdIns(3,4,5)P3 at the same location, creating reciprocal regulation.","method":"Co-immunoprecipitation, siRNA knockdown, domain mutagenesis, live-cell imaging of lamellipodia","journal":"The Journal of biological chemistry","confidence":"High","confidence_rationale":"Tier 2 — multiple orthogonal methods (co-IP, mutagenesis, KD, live imaging), clear mechanistic model with reciprocal regulation","pmids":["20236936"],"is_preprint":false},{"year":2013,"finding":"LL5β (PHLDB2) interacts with three actin cytoskeleton regulators—Amotl2, Asef2, and Flii—in myotubes, and these proteins are associated with synaptic podosomes/invadopodia. LL5β is a component of synaptic podosomes that promote NMJ remodeling. Depletion of Amotl2 (an LL5β-interacting protein) increases the size of synaptic podosomes and alters postsynaptic topology.","method":"Affinity purification of LL5β-associated proteins (mass spectrometry), co-immunoprecipitation, RNAi knockdown with morphological readout","journal":"Journal of cell science","confidence":"High","confidence_rationale":"Tier 2 — MS-based complex identification confirmed by co-IP, loss-of-function with defined morphological phenotype","pmids":["23525008"],"is_preprint":false},{"year":2014,"finding":"LL5β acts downstream of BMP2-induced PI3K (p55γ/p110α) signaling at the cell cortex. BMP2 stimulation produces PIP3 at the leading edge, which recruits LL5β to the cytocortex; knockdown of p55γ or LL5β impairs BMP2-induced cortical actin rearrangements, lamellipodia formation, and chemotaxis of mesenchymal progenitors.","method":"Mass spectrometry (identification of LL5β as BMP2 effector), protein interaction studies, live-cell imaging, siRNA knockdown of p55γ and LL5β, PI3K pharmacological inhibition, cell migration assays","journal":"BMC biology","confidence":"High","confidence_rationale":"Tier 2 — MS identification, live imaging, RNAi with defined functional phenotype, multiple orthogonal methods","pmids":["24885555"],"is_preprint":false},{"year":2015,"finding":"LL5β (PHLDB2) is required for CLASP2-mediated microtubule capture at the NMJ membrane. Knockdown of LL5β or forced expression of a CLASP2 fragment blocking the CLASP2/LL5β interaction inhibits microtubule capture and impairs focal AChR vesicle delivery to AChR clusters. In vivo knockdown of LL5β at the NMJ reduces AChR density and insertion into the postsynaptic membrane. This transport system is organized by agrin through PI3K→GSK3β→CLASP2→LL5β.","method":"RNAi knockdown, dominant-negative fragment expression, live imaging of vesicle delivery, in vivo NMJ analysis, microtubule/actin depolymerization","journal":"Molecular biology of the cell","confidence":"High","confidence_rationale":"Tier 2 — multiple orthogonal loss-of-function approaches in vitro and in vivo, clear epistasis establishing pathway position","pmids":["25589673"],"is_preprint":false},{"year":2016,"finding":"Prickle1 associates with CLASPs and LL5β (PHLDB2), and is required for LL5β-dependent accumulation of CLASPs at the cell edge. LL5β and CLASPs together mediate microtubule-dependent focal adhesion disassembly during cell retraction; knockdown of CLASPs or LL5β suppresses Prickle1-dependent cell polarization and migration.","method":"Co-immunoprecipitation, siRNA knockdown, live-cell imaging, focal adhesion disassembly assay, cell migration assay","journal":"Journal of cell science","confidence":"High","confidence_rationale":"Tier 2 — reciprocal co-IP, RNAi epistasis, live imaging with functional phenotype","pmids":["27378169"],"is_preprint":false},{"year":2019,"finding":"PHLDB2 binds MDM2 and facilitates MDM2-mediated E-cadherin degradation, contributing to EMT. PHLDB2 knockdown attenuates colon cancer cell migration and invasion, and prevents TGF-β-induced E-cadherin reduction.","method":"Co-immunoprecipitation, siRNA knockdown, western blot, migration/invasion assays","journal":"Cancer cell international","confidence":"Medium","confidence_rationale":"Tier 3 — single co-IP for MDM2 interaction, supported by knockdown phenotype; single lab","pmids":["31346319"],"is_preprint":false},{"year":2019,"finding":"Phldb2 (PHLDB2) binds PSD-95 and is required for its localization and turnover in dendritic spines. Phldb2 also binds GluA1 and GluA2 (AMPA receptor subunits) and is indispensable for the interaction between NMDA receptors and CaMKII, as well as for synaptic AMPA receptor density. BDNF causes PIP3-dependent Phldb2 recruitment to the postsynaptic membrane in spines; Phldb2 knockout mice show impaired LTP and memory formation.","method":"Co-immunoprecipitation, PI3K inhibition, live imaging of dendritic spines, Phldb2 knockout mice, LTP electrophysiology, memory behavioral assays","journal":"Scientific reports","confidence":"High","confidence_rationale":"Tier 2 — multiple co-IPs, KO mouse with defined synaptic and behavioral phenotypes, multiple orthogonal methods","pmids":["30867511"],"is_preprint":false},{"year":2021,"finding":"PHLDB2 stabilizes EGFR and promotes its nuclear translocation, leading to EGFR signaling activation and cetuximab resistance in colorectal cancer. The Arg1163 residue of PHLDB2 is crucial for its interaction with EGFR, and the R1163A mutation abrogates its regulatory function in EGFR signaling. Chemotherapy-induced oxidative stress promotes METTL14-mediated N6-methyladenosine modification of PHLDB2 mRNA, facilitating its protein expression.","method":"Mass spectrometry, Duolink proximity ligation assay, co-immunoprecipitation, site-directed mutagenesis (R1163A), RNA immunoprecipitation, CRC cell lines and mouse models","journal":"Cellular and molecular gastroenterology and hepatology","confidence":"High","confidence_rationale":"Tier 1-2 — multiple orthogonal methods (MS, PLA, co-IP, mutagenesis, m6A modification), in vivo validation","pmids":["34952201"],"is_preprint":false},{"year":2022,"finding":"The Legionella pneumophila Dot/Icm effector Lem8 (Lpg1290) is a protease whose catalytic activity depends on a Cys-His-Asp motif. Lem8 interacts with host 14-3-3ζ, which activates its protease activity and is required for Lem8 self-cleavage. Lem8 cleaves host PHLDB2, and this proteolysis inhibits host cell migration.","method":"Biochemical protease assays, active-site mutagenesis of Cys-His-Asp motif, co-immunoprecipitation with 14-3-3ζ, cell migration assays after Lem8 expression","journal":"eLife","confidence":"High","confidence_rationale":"Tier 1 — biochemical reconstitution of protease activity, active-site mutagenesis, identification of PHLDB2 as substrate with functional consequence","pmids":["35175192"],"is_preprint":false},{"year":2022,"finding":"Phldb2 binds drebrin A (adult-type isoform) but not drebrin E (embryonic-type isoform) in hippocampal neurons. In Phldb2-/- mice, drebrin A localization in hippocampal spines is altered, immature (filopodium-type) spines increase, and mature (mushroom-type) spines decrease in CA1 regions. Phldb2 suppresses formation of abnormal filopodium structures induced by drebrin A overexpression.","method":"Co-immunoprecipitation (isoform-specific), Phldb2 knockout mice, morphological spine analysis, drebrin A overexpression assay","journal":"Neuroscience research","confidence":"Medium","confidence_rationale":"Tier 2 — co-IP with isoform specificity, KO mouse with defined morphological phenotype; single lab","pmids":["36162735"],"is_preprint":false},{"year":2023,"finding":"LL5β (PHLDB2) directly interacts with ERC1 (ELKS/ERC1) through minimal binding regions LL5β(381-510) and ERC1(270-370), which include predicted intrinsically disordered regions and form a high-affinity heterotypic complex. Expression of the LL5β(381-510) fragment delocalizes endogenous ERC1 from the leading edge of migrating cells, reduces invadopodium density, and inhibits transwell invasion.","method":"Co-immunoprecipitation, NMR spectroscopy, biochemical fragment characterization, live-cell imaging, transwell invasion assay","journal":"PloS one","confidence":"Medium","confidence_rationale":"Tier 2 — NMR confirmation of interaction, co-IP, functional perturbation with defined phenotype; single lab","pmids":["37437062"],"is_preprint":false},{"year":2025,"finding":"PHLDB2 contains intrinsically disordered regions (IDRs) and forms dynamic, reversible liquid-liquid phase separation (LLPS) condensates, as confirmed by FRAP assays. PHLDB2 knockdown inhibits EMT (upregulates E-cadherin, downregulates N-cadherin, vimentin, Snail, MMP-2), reduces tumor growth, and impairs pulmonary metastasis in TNBC xenograft models.","method":"PONDR disorder prediction, FRAP assay, KD/OE in cell lines, in vivo xenograft and metastasis models","journal":"Cancer medicine","confidence":"Medium","confidence_rationale":"Tier 2-3 — FRAP confirms LLPS in cells, supported by in vivo KD phenotype; single lab, no reconstitution","pmids":["41319208"],"is_preprint":false},{"year":2025,"finding":"LL5β (PHLDB2) cortical patches at the beta cell periphery co-localize with ELKS to define secretion hot spots for directed insulin secretion; however, secretion events occur specifically at the margins of ELKS patches and at cortical sites devoid of microtubules, indicating that local MT disassembly within LL5β/ELKS cortical platforms governs the precise location of insulin secretion.","method":"TIRF microscopy of intact mouse islets, live imaging of secretion events relative to ELKS/LL5β patches, MT depolymerization experiments","journal":"Molecular biology of the cell","confidence":"Medium","confidence_rationale":"Tier 2 — live TIRF imaging in intact tissue with spatial correlation to secretion events; single study","pmids":["40366873"],"is_preprint":false}],"current_model":"PHLDB2 (LL5β) is a PIP3-sensing scaffold protein whose PH domain binds PtdIns(3,4,5)P3 to direct its cortical recruitment downstream of PI3K signaling, where it assembles multi-protein platforms—including CLASPs, ELKS/ERC1, and filamins—that anchor microtubule plus ends to the cell cortex, regulate focal adhesion disassembly and directed vesicle delivery, organize postsynaptic AChR clusters and LTP-associated receptor trafficking at the NMJ and hippocampal synapses (via PSD-95, GluA1/2, and drebrin A interactions), promote cell migration and EMT (partly through MDM2-mediated E-cadherin degradation and EGFR stabilization), and can undergo liquid-liquid phase separation through intrinsically disordered regions; additionally, PHLDB2 is a direct substrate of the Legionella effector protease Lem8 (activated by host 14-3-3ζ), whose cleavage of PHLDB2 inhibits host cell migration."},"narrative":{"teleology":[{"year":2002,"claim":"Establishing that PHLDB2 is a PIP3-selective lipid-binding protein whose localization is dynamically controlled by PI3K, and that it independently binds γ-filamin, defined its dual identity as a lipid sensor and cytoskeletal adaptor.","evidence":"In vitro PIP3 binding with PH domain mutagenesis, PI3K inhibition, co-IP with filamin in mammalian cells","pmids":["12376540"],"confidence":"High","gaps":["No cortical function or downstream effector yet identified","PH domain structure not resolved","Filamin binding significance for cell behavior unknown"]},{"year":2005,"claim":"Discovery that PHLDB2 localizes to the postsynaptic NMJ membrane and is required for AChR aggregation revealed its first physiological function—organizing postsynaptic receptor clusters.","evidence":"Microarray identification, subcellular fractionation, siRNA/dominant-negative perturbation with AChR clustering readout in myotubes","pmids":["15851520"],"confidence":"High","gaps":["Mechanism linking PHLDB2 to AChR aggregation unclear","No in vivo NMJ phenotype yet shown"]},{"year":2006,"claim":"Identification of a cortical LL5β–ELKS–CLASP complex that captures microtubule plus ends at the cell periphery established PHLDB2 as a PIP3-dependent organizer of cortical microtubule anchoring, independent of focal adhesions.","evidence":"Mass spectrometry complex identification, reciprocal co-IP, RNAi with live-cell imaging in HeLa cells; domain mapping of filamin C binding with PI3K inhibition","pmids":["16824950","17174070"],"confidence":"High","gaps":["Structural basis of LL5β–ELKS and LL5β–CLASP interactions unknown","Functional consequence for cell migration not yet tested"]},{"year":2010,"claim":"Demonstrating that PIP3-recruited PHLDB2 brings Filamin A and SHIP2 to the leading edge, creating a negative-feedback loop that locally dephosphorylates PIP3, explained how PHLDB2 both responds to and shapes the PIP3 gradient during lamellipodium formation.","evidence":"Co-IP, siRNA, PH domain mutagenesis, EGF-stimulated live-cell imaging of lamellipodia","pmids":["20236936"],"confidence":"High","gaps":["Quantitative kinetics of feedback loop not measured","Relative contributions of Filamin A vs Filamin C isoforms at the cortex unclear"]},{"year":2013,"claim":"Identification of PHLDB2 as a component of synaptic podosomes that interacts with actin regulators Amotl2, Asef2, and Flii expanded its role at the NMJ from receptor clustering to active membrane remodeling.","evidence":"Affinity purification/MS of LL5β-associated proteins, co-IP, RNAi with podosome morphology readout in myotubes","pmids":["23525008"],"confidence":"High","gaps":["Direct vs indirect nature of interactions with Asef2 and Flii not resolved","In vivo relevance for NMJ remodeling not demonstrated"]},{"year":2014,"claim":"Placing PHLDB2 downstream of BMP2→PI3K(p55γ/p110α) signaling for cortical actin rearrangement and chemotaxis showed it acts as a general effector node for multiple growth factor–PI3K cascades, not only PDGF/EGF.","evidence":"MS identification, live-cell imaging, siRNA of p55γ and LL5β, cell migration assays in mesenchymal progenitors","pmids":["24885555"],"confidence":"High","gaps":["Whether BMP2 engages the same LL5β–ELKS–CLASP cortical platform not tested"]},{"year":2015,"claim":"Demonstrating that PHLDB2 is essential for CLASP2-mediated microtubule capture and directed AChR vesicle delivery at the NMJ in vivo, and positioning it in the agrin→PI3K→GSK3β→CLASP2→LL5β pathway, provided a complete signaling axis for postsynaptic receptor maintenance.","evidence":"RNAi, dominant-negative CLASP2 fragment, live vesicle imaging, in vivo NMJ analysis in mouse","pmids":["25589673"],"confidence":"High","gaps":["Whether other receptor types use the same CLASP2–LL5β delivery route not explored"]},{"year":2016,"claim":"Connecting the planar cell polarity protein Prickle1 to PHLDB2–CLASP complexes for focal adhesion disassembly during cell retraction revealed how PHLDB2 integrates polarity cues with microtubule-dependent adhesion turnover during migration.","evidence":"Reciprocal co-IP, siRNA epistasis, live-cell imaging of focal adhesion disassembly and migration","pmids":["27378169"],"confidence":"High","gaps":["Molecular basis of Prickle1–LL5β interaction not mapped","Whether Wnt/PCP signaling directly regulates this complex unclear"]},{"year":2019,"claim":"Two studies extended PHLDB2's roles to cancer biology and synaptic plasticity: PHLDB2 promotes EMT by facilitating MDM2-mediated E-cadherin degradation in colon cancer, and is required for PSD-95 localization, AMPA receptor density, LTP, and memory in hippocampal synapses.","evidence":"Co-IP of PHLDB2–MDM2 with migration/invasion assays; Phldb2 KO mice with LTP electrophysiology, co-IP with PSD-95/GluA1/GluA2, behavioral memory tests","pmids":["31346319","30867511"],"confidence":"High","gaps":["MDM2 interaction awaits reciprocal validation and structural characterization","Relative contributions of PHLDB2's PIP3 binding vs protein scaffolding to synaptic function not separated"]},{"year":2021,"claim":"Showing that PHLDB2 stabilizes EGFR and promotes its nuclear translocation via a critical Arg1163 contact, and that chemotherapy-induced m6A modification of PHLDB2 mRNA upregulates its expression, identified a new axis for therapy resistance in colorectal cancer.","evidence":"MS, proximity ligation assay, co-IP, R1163A mutagenesis, RNA immunoprecipitation for m6A, CRC xenograft models","pmids":["34952201"],"confidence":"High","gaps":["Crystal structure of PHLDB2–EGFR interface not available","Whether EGFR stabilization is PIP3-dependent not tested"]},{"year":2022,"claim":"Identification of PHLDB2 as a direct substrate of the Legionella effector protease Lem8—activated by host 14-3-3ζ—established a pathogen strategy to disable host cell migration by destroying a key cortical scaffold.","evidence":"Biochemical protease reconstitution, active-site mutagenesis, co-IP with 14-3-3ζ, cell migration assays","pmids":["35175192"],"confidence":"High","gaps":["Cleavage site in PHLDB2 not mapped","Whether Lem8 targets other cortical scaffolds unknown"]},{"year":2022,"claim":"Discovery of isoform-specific binding between PHLDB2 and drebrin A (but not drebrin E), and the altered spine maturation in Phldb2 KO mice, established PHLDB2 as a regulator of dendritic spine morphogenesis through actin remodeling.","evidence":"Isoform-specific co-IP, Phldb2 KO mice with spine morphology analysis in CA1","pmids":["36162735"],"confidence":"Medium","gaps":["Binding interface between PHLDB2 and drebrin A not mapped","Functional relationship to LTP phenotype from prior KO study not tested directly"]},{"year":2023,"claim":"Mapping the minimal LL5β–ERC1 binding regions to intrinsically disordered segments and showing that disrupting this interaction delocalizes ERC1 and inhibits invadopodium-driven invasion provided structural insight into how the cortical platform assembles.","evidence":"NMR spectroscopy, co-IP, fragment expression with live imaging and transwell invasion assay","pmids":["37437062"],"confidence":"Medium","gaps":["Full structural model of LL5β–ERC1 complex not resolved","Whether LLPS contributes to LL5β–ERC1 platform formation not addressed"]},{"year":2025,"claim":"Two studies revealed that PHLDB2 undergoes liquid-liquid phase separation via its IDRs to promote EMT and metastasis in TNBC, and that LL5β/ELKS cortical patches define insulin secretion hot spots in pancreatic β-cells where local microtubule disassembly permits exocytosis.","evidence":"FRAP-confirmed LLPS, KD with in vivo xenograft/metastasis models; TIRF microscopy of secretion events in intact mouse islets","pmids":["41319208","40366873"],"confidence":"Medium","gaps":["LLPS reconstitution from purified components not performed","Causal link between LL5β LLPS and cortical platform function not established","Mechanism of local MT disassembly at LL5β/ELKS patch margins unclear"]},{"year":null,"claim":"Key unresolved questions include the atomic structure of PHLDB2 and its cortical complex, whether LLPS is functionally required for scaffold assembly, and how PHLDB2's synaptic and migratory functions are differentially regulated in distinct cell types.","evidence":"","pmids":[],"confidence":"High","gaps":["No high-resolution structure of PHLDB2 or any of its complexes","Whether LLPS is a cause or consequence of cortical platform assembly is unknown","Cell-type-specific regulatory mechanisms for PHLDB2 recruitment and function are unexplored"]}],"mechanism_profile":{"molecular_activity":[{"term_id":"GO:0008289","term_label":"lipid binding","supporting_discovery_ids":[0,1,2]},{"term_id":"GO:0060090","term_label":"molecular adaptor activity","supporting_discovery_ids":[2,4,7,8]},{"term_id":"GO:0008092","term_label":"cytoskeletal protein binding","supporting_discovery_ids":[0,3,4,5]}],"localization":[{"term_id":"GO:0005886","term_label":"plasma membrane","supporting_discovery_ids":[0,1,2,4,6,10,16]},{"term_id":"GO:0005829","term_label":"cytosol","supporting_discovery_ids":[0,3]},{"term_id":"GO:0005856","term_label":"cytoskeleton","supporting_discovery_ids":[2,5,8]}],"pathway":[{"term_id":"R-HSA-162582","term_label":"Signal Transduction","supporting_discovery_ids":[0,4,6,11]},{"term_id":"R-HSA-1500931","term_label":"Cell-Cell communication","supporting_discovery_ids":[1,7,10]},{"term_id":"R-HSA-112316","term_label":"Neuronal System","supporting_discovery_ids":[10,13]},{"term_id":"R-HSA-9609507","term_label":"Protein localization","supporting_discovery_ids":[7,16]}],"complexes":["LL5β–ELKS–CLASP cortical platform"],"partners":["ELKS/ERC1","CLASP2","FLNA","FLNC","DLG4","MDM2","EGFR","DBN1"],"other_free_text":[]},"mechanistic_narrative":"PHLDB2 (LL5β) is a PtdIns(3,4,5)P3-sensing scaffold protein that couples PI3K signaling to cortical microtubule capture, focal adhesion dynamics, directed vesicle delivery, and postsynaptic organization. Its C-terminal PH domain selectively binds PIP3 to drive plasma membrane recruitment, where it nucleates cortical platforms containing ELKS/ERC1, CLASPs, and filamins that anchor microtubule plus ends, promote focal adhesion disassembly during cell migration, and define exocytic hot spots for insulin secretion [PMID:12376540, PMID:16824950, PMID:27378169, PMID:40366873]. At the neuromuscular junction and hippocampal synapses, PHLDB2 organizes AChR clustering via CLASP2-dependent vesicle delivery, binds PSD-95 and AMPA receptor subunits to regulate synaptic receptor density, and interacts with drebrin A to control dendritic spine maturation; Phldb2 knockout mice exhibit impaired LTP and memory formation [PMID:25589673, PMID:30867511, PMID:36162735]. PHLDB2 also promotes epithelial–mesenchymal transition by facilitating MDM2-mediated E-cadherin degradation and stabilizing EGFR, and is a direct substrate of the Legionella effector protease Lem8, whose cleavage of PHLDB2 inhibits host cell migration [PMID:31346319, PMID:34952201, PMID:35175192]."},"prefetch_data":{"uniprot":{"accession":"Q86SQ0","full_name":"Pleckstrin homology-like domain family B member 2","aliases":["Protein LL5-beta"],"length_aa":1253,"mass_kda":142.2,"function":"Seems to be involved in the assembly of the postsynaptic apparatus. May play a role in acetyl-choline receptor (AChR) aggregation in the postsynaptic membrane (By similarity)","subcellular_location":"Cytoplasm; Cytoplasm, cell cortex; Membrane; Cell projection, podosome","url":"https://www.uniprot.org/uniprotkb/Q86SQ0/entry"},"depmap":{"release":"DepMap","has_data":true,"is_common_essential":false,"resolved_as":"","url":"https://depmap.org/portal/gene/PHLDB2","classification":"Not Classified","n_dependent_lines":1,"n_total_lines":1208,"dependency_fraction":0.0008278145695364238},"opencell":{"profiled":false,"resolved_as":"","ensg_id":"","cell_line_id":"","localizations":[],"interactors":[{"gene":"CALD1","stoichiometry":0.2},{"gene":"CALM3","stoichiometry":0.2},{"gene":"CAPZB","stoichiometry":0.2}],"url":"https://opencell.sf.czbiohub.org/search/PHLDB2","total_profiled":1310},"omim":[{"mim_id":"610298","title":"PLECKSTRIN HOMOLOGY-LIKE DOMAIN, FAMILY B, MEMBER 2; PHLDB2","url":"https://www.omim.org/entry/610298"},{"mim_id":"607127","title":"ELKS/RAB6-INTERACTING/CAST FAMILY, MEMBER 1; ERC1","url":"https://www.omim.org/entry/607127"}],"hpa":{"profiled":true,"resolved_as":"","reliability":"Supported","locations":[{"location":"Plasma membrane","reliability":"Supported"},{"location":"Cytosol","reliability":"Supported"}],"tissue_specificity":"Low tissue specificity","tissue_distribution":"Detected in many","driving_tissues":[],"url":"https://www.proteinatlas.org/search/PHLDB2"},"hgnc":{"alias_symbol":["LL5beta","FLJ21791","LL5b"],"prev_symbol":[]},"alphafold":{"accession":"Q86SQ0","domains":[{"cath_id":"1.10.287,1.10.287","chopping":"586-816","consensus_level":"high","plddt":93.6861,"start":586,"end":816},{"cath_id":"2.30.29.30","chopping":"1121-1252","consensus_level":"high","plddt":88.1395,"start":1121,"end":1252},{"cath_id":"1.20.5","chopping":"1045-1107","consensus_level":"medium","plddt":83.5268,"start":1045,"end":1107}],"viewer_url":"https://alphafold.ebi.ac.uk/entry/Q86SQ0","model_url":"https://alphafold.ebi.ac.uk/files/AF-Q86SQ0-F1-model_v6.cif","pae_url":"https://alphafold.ebi.ac.uk/files/AF-Q86SQ0-F1-predicted_aligned_error_v6.png","plddt_mean":58.12},"mouse_models":{"mgi_url":"https://www.informatics.jax.org/marker/summary?nomen=PHLDB2","jax_strain_url":"https://www.jax.org/strain/search?query=PHLDB2"},"sequence":{"accession":"Q86SQ0","fasta_url":"https://rest.uniprot.org/uniprotkb/Q86SQ0.fasta","uniprot_url":"https://www.uniprot.org/uniprotkb/Q86SQ0/entry","alphafold_viewer_url":"https://alphafold.ebi.ac.uk/entry/Q86SQ0"}},"corpus_meta":[{"pmid":"16824950","id":"PMC_16824950","title":"CLASPs attach microtubule plus ends to the cell cortex through a complex with LL5beta.","date":"2006","source":"Developmental cell","url":"https://pubmed.ncbi.nlm.nih.gov/16824950","citation_count":256,"is_preprint":false},{"pmid":"15851520","id":"PMC_15851520","title":"LL5beta: a regulator of postsynaptic differentiation identified in a screen for synaptically enriched transcripts at the neuromuscular junction.","date":"2005","source":"The Journal of cell biology","url":"https://pubmed.ncbi.nlm.nih.gov/15851520","citation_count":73,"is_preprint":false},{"pmid":"28392396","id":"PMC_28392396","title":"p53 target miR-29c-3p suppresses colon cancer cell invasion and migration through inhibition of PHLDB2.","date":"2017","source":"Biochemical and biophysical research communications","url":"https://pubmed.ncbi.nlm.nih.gov/28392396","citation_count":50,"is_preprint":false},{"pmid":"12376540","id":"PMC_12376540","title":"LL5beta is a phosphatidylinositol (3,4,5)-trisphosphate sensor that can bind the cytoskeletal adaptor, gamma-filamin.","date":"2002","source":"The Journal of biological chemistry","url":"https://pubmed.ncbi.nlm.nih.gov/12376540","citation_count":45,"is_preprint":false},{"pmid":"23525008","id":"PMC_23525008","title":"Amotl2 interacts with LL5β, localizes to podosomes and regulates postsynaptic differentiation in muscle.","date":"2013","source":"Journal of cell science","url":"https://pubmed.ncbi.nlm.nih.gov/23525008","citation_count":44,"is_preprint":false},{"pmid":"24885555","id":"PMC_24885555","title":"BMP2-induced chemotaxis requires PI3K p55γ/p110α-dependent phosphatidylinositol (3,4,5)-triphosphate production and LL5β recruitment at the cytocortex.","date":"2014","source":"BMC biology","url":"https://pubmed.ncbi.nlm.nih.gov/24885555","citation_count":34,"is_preprint":false},{"pmid":"27378169","id":"PMC_27378169","title":"Prickle1 promotes focal adhesion disassembly in cooperation with the CLASP-LL5β complex in migrating 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Promoting Phosphorylation of AKT3.","date":"2021","source":"Frontiers in cell and developmental biology","url":"https://pubmed.ncbi.nlm.nih.gov/34746118","citation_count":22,"is_preprint":false},{"pmid":"33320958","id":"PMC_33320958","title":"Oncometabolite L-2-hydroxyglurate directly induces vasculogenic mimicry through PHLDB2 in renal cell carcinoma.","date":"2021","source":"International journal of cancer","url":"https://pubmed.ncbi.nlm.nih.gov/33320958","citation_count":19,"is_preprint":false},{"pmid":"31346319","id":"PMC_31346319","title":"Oncogenic effect of PHLDB2 is associated with epithelial-mesenchymal transition and E-cadherin regulation in colorectal cancer.","date":"2019","source":"Cancer cell international","url":"https://pubmed.ncbi.nlm.nih.gov/31346319","citation_count":18,"is_preprint":false},{"pmid":"30867511","id":"PMC_30867511","title":"PIP3-Phldb2 is crucial for LTP regulating synaptic NMDA and AMPA receptor density and PSD95 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PtdIns(3,4,5)P3 drives cytoplasmic and plasma membrane localization. LL5β also binds the cytoskeletal adaptor γ-filamin tightly in vitro and in vivo in a PI3K-independent manner.\",\n      \"method\": \"In vitro PtdIns(3,4,5)P3 binding assay, PH domain mutagenesis, pharmacological PI3K inhibition, PI3K-deficient PDGFR mutants, co-immunoprecipitation, co-localization imaging\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 — in vitro binding assay with mutagenesis, replicated with multiple orthogonal methods in a single study\",\n      \"pmids\": [\"12376540\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2005,\n      \"finding\": \"LL5β (PHLDB2) is enriched at the postsynaptic membrane of the neuromuscular junction (NMJ), localizes to the cytoplasmic face of the postsynaptic membrane bordering regions of highest AChR density, binds phosphoinositides and filamin, and is required for AChR aggregation in myotubes (perturbation of LL5β expression inhibits AChR aggregation).\",\n      \"method\": \"Microarray identification, subcellular fractionation/localization, filamin binding assay, siRNA/dominant-negative perturbation with AChR aggregation readout\",\n      \"journal\": \"The Journal of cell biology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — reciprocal binding assays, loss-of-function with specific phenotypic readout, localization tied to function\",\n      \"pmids\": [\"15851520\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2006,\n      \"finding\": \"LL5β (PHLDB2) forms a cortical complex with ELKS and CLASPs at the cell cortex and leading edge. LL5β is required for cortical CLASP accumulation and microtubule stabilization at the cortex of HeLa cells. LL5β is a PIP3-binding protein whose cortical recruitment is regulated by PI3K activity but does not require intact microtubules. Cortical LL5β/ELKS clusters do not overlap with focal adhesions but form in their vicinity and can affect focal adhesion size.\",\n      \"method\": \"Mass spectrometry-based identification of partners, co-immunoprecipitation, RNAi knockdown, live-cell imaging, PI3K inhibition\",\n      \"journal\": \"Developmental cell\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — MS-identified complex, reciprocal co-IP, clean RNAi with defined cellular phenotypes; highly cited foundational study\",\n      \"pmids\": [\"16824950\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2006,\n      \"finding\": \"An N-terminal region of LL5β mediates binding to the C-terminus of filamins (including filamin C). Under very low PI3K activity, this N-terminal region plus an additional domain localizes the LL5β–filamin complex to punctate structures also decorated by L-FILIP. PtdIns(3,4,5)P3 binding to the C-terminal PH domain of LL5β prevents localization to these structures under high PI3K activity.\",\n      \"method\": \"Domain mapping/mutagenesis, co-immunoprecipitation, subcellular localization imaging with PI3K inhibition\",\n      \"journal\": \"Cellular signalling\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — domain-mapping with mutagenesis, localization studies; single lab\",\n      \"pmids\": [\"17174070\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2010,\n      \"finding\": \"PtdIns(3,4,5)P3-localized LL5β recruits Filamin A and SHIP2 (via Filamin A) to the plasma membrane at sites of PIP3 accumulation, promoting lamellipodium formation. Depletion of either Filamin A or LL5β, or expression of a PtdIns(3,4,5)P3-binding-deficient LL5β mutant, inhibits EGF-induced large lamellipodium formation. Co-recruited SHIP2 dephosphorylates PtdIns(3,4,5)P3 at the same location, creating reciprocal regulation.\",\n      \"method\": \"Co-immunoprecipitation, siRNA knockdown, domain mutagenesis, live-cell imaging of lamellipodia\",\n      \"journal\": \"The Journal of biological chemistry\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — multiple orthogonal methods (co-IP, mutagenesis, KD, live imaging), clear mechanistic model with reciprocal regulation\",\n      \"pmids\": [\"20236936\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2013,\n      \"finding\": \"LL5β (PHLDB2) interacts with three actin cytoskeleton regulators—Amotl2, Asef2, and Flii—in myotubes, and these proteins are associated with synaptic podosomes/invadopodia. LL5β is a component of synaptic podosomes that promote NMJ remodeling. Depletion of Amotl2 (an LL5β-interacting protein) increases the size of synaptic podosomes and alters postsynaptic topology.\",\n      \"method\": \"Affinity purification of LL5β-associated proteins (mass spectrometry), co-immunoprecipitation, RNAi knockdown with morphological readout\",\n      \"journal\": \"Journal of cell science\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — MS-based complex identification confirmed by co-IP, loss-of-function with defined morphological phenotype\",\n      \"pmids\": [\"23525008\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2014,\n      \"finding\": \"LL5β acts downstream of BMP2-induced PI3K (p55γ/p110α) signaling at the cell cortex. BMP2 stimulation produces PIP3 at the leading edge, which recruits LL5β to the cytocortex; knockdown of p55γ or LL5β impairs BMP2-induced cortical actin rearrangements, lamellipodia formation, and chemotaxis of mesenchymal progenitors.\",\n      \"method\": \"Mass spectrometry (identification of LL5β as BMP2 effector), protein interaction studies, live-cell imaging, siRNA knockdown of p55γ and LL5β, PI3K pharmacological inhibition, cell migration assays\",\n      \"journal\": \"BMC biology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — MS identification, live imaging, RNAi with defined functional phenotype, multiple orthogonal methods\",\n      \"pmids\": [\"24885555\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2015,\n      \"finding\": \"LL5β (PHLDB2) is required for CLASP2-mediated microtubule capture at the NMJ membrane. Knockdown of LL5β or forced expression of a CLASP2 fragment blocking the CLASP2/LL5β interaction inhibits microtubule capture and impairs focal AChR vesicle delivery to AChR clusters. In vivo knockdown of LL5β at the NMJ reduces AChR density and insertion into the postsynaptic membrane. This transport system is organized by agrin through PI3K→GSK3β→CLASP2→LL5β.\",\n      \"method\": \"RNAi knockdown, dominant-negative fragment expression, live imaging of vesicle delivery, in vivo NMJ analysis, microtubule/actin depolymerization\",\n      \"journal\": \"Molecular biology of the cell\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — multiple orthogonal loss-of-function approaches in vitro and in vivo, clear epistasis establishing pathway position\",\n      \"pmids\": [\"25589673\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2016,\n      \"finding\": \"Prickle1 associates with CLASPs and LL5β (PHLDB2), and is required for LL5β-dependent accumulation of CLASPs at the cell edge. LL5β and CLASPs together mediate microtubule-dependent focal adhesion disassembly during cell retraction; knockdown of CLASPs or LL5β suppresses Prickle1-dependent cell polarization and migration.\",\n      \"method\": \"Co-immunoprecipitation, siRNA knockdown, live-cell imaging, focal adhesion disassembly assay, cell migration assay\",\n      \"journal\": \"Journal of cell science\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — reciprocal co-IP, RNAi epistasis, live imaging with functional phenotype\",\n      \"pmids\": [\"27378169\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2019,\n      \"finding\": \"PHLDB2 binds MDM2 and facilitates MDM2-mediated E-cadherin degradation, contributing to EMT. PHLDB2 knockdown attenuates colon cancer cell migration and invasion, and prevents TGF-β-induced E-cadherin reduction.\",\n      \"method\": \"Co-immunoprecipitation, siRNA knockdown, western blot, migration/invasion assays\",\n      \"journal\": \"Cancer cell international\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 3 — single co-IP for MDM2 interaction, supported by knockdown phenotype; single lab\",\n      \"pmids\": [\"31346319\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2019,\n      \"finding\": \"Phldb2 (PHLDB2) binds PSD-95 and is required for its localization and turnover in dendritic spines. Phldb2 also binds GluA1 and GluA2 (AMPA receptor subunits) and is indispensable for the interaction between NMDA receptors and CaMKII, as well as for synaptic AMPA receptor density. BDNF causes PIP3-dependent Phldb2 recruitment to the postsynaptic membrane in spines; Phldb2 knockout mice show impaired LTP and memory formation.\",\n      \"method\": \"Co-immunoprecipitation, PI3K inhibition, live imaging of dendritic spines, Phldb2 knockout mice, LTP electrophysiology, memory behavioral assays\",\n      \"journal\": \"Scientific reports\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 — multiple co-IPs, KO mouse with defined synaptic and behavioral phenotypes, multiple orthogonal methods\",\n      \"pmids\": [\"30867511\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2021,\n      \"finding\": \"PHLDB2 stabilizes EGFR and promotes its nuclear translocation, leading to EGFR signaling activation and cetuximab resistance in colorectal cancer. The Arg1163 residue of PHLDB2 is crucial for its interaction with EGFR, and the R1163A mutation abrogates its regulatory function in EGFR signaling. Chemotherapy-induced oxidative stress promotes METTL14-mediated N6-methyladenosine modification of PHLDB2 mRNA, facilitating its protein expression.\",\n      \"method\": \"Mass spectrometry, Duolink proximity ligation assay, co-immunoprecipitation, site-directed mutagenesis (R1163A), RNA immunoprecipitation, CRC cell lines and mouse models\",\n      \"journal\": \"Cellular and molecular gastroenterology and hepatology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1-2 — multiple orthogonal methods (MS, PLA, co-IP, mutagenesis, m6A modification), in vivo validation\",\n      \"pmids\": [\"34952201\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2022,\n      \"finding\": \"The Legionella pneumophila Dot/Icm effector Lem8 (Lpg1290) is a protease whose catalytic activity depends on a Cys-His-Asp motif. Lem8 interacts with host 14-3-3ζ, which activates its protease activity and is required for Lem8 self-cleavage. Lem8 cleaves host PHLDB2, and this proteolysis inhibits host cell migration.\",\n      \"method\": \"Biochemical protease assays, active-site mutagenesis of Cys-His-Asp motif, co-immunoprecipitation with 14-3-3ζ, cell migration assays after Lem8 expression\",\n      \"journal\": \"eLife\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 — biochemical reconstitution of protease activity, active-site mutagenesis, identification of PHLDB2 as substrate with functional consequence\",\n      \"pmids\": [\"35175192\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2022,\n      \"finding\": \"Phldb2 binds drebrin A (adult-type isoform) but not drebrin E (embryonic-type isoform) in hippocampal neurons. In Phldb2-/- mice, drebrin A localization in hippocampal spines is altered, immature (filopodium-type) spines increase, and mature (mushroom-type) spines decrease in CA1 regions. Phldb2 suppresses formation of abnormal filopodium structures induced by drebrin A overexpression.\",\n      \"method\": \"Co-immunoprecipitation (isoform-specific), Phldb2 knockout mice, morphological spine analysis, drebrin A overexpression assay\",\n      \"journal\": \"Neuroscience research\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — co-IP with isoform specificity, KO mouse with defined morphological phenotype; single lab\",\n      \"pmids\": [\"36162735\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2023,\n      \"finding\": \"LL5β (PHLDB2) directly interacts with ERC1 (ELKS/ERC1) through minimal binding regions LL5β(381-510) and ERC1(270-370), which include predicted intrinsically disordered regions and form a high-affinity heterotypic complex. Expression of the LL5β(381-510) fragment delocalizes endogenous ERC1 from the leading edge of migrating cells, reduces invadopodium density, and inhibits transwell invasion.\",\n      \"method\": \"Co-immunoprecipitation, NMR spectroscopy, biochemical fragment characterization, live-cell imaging, transwell invasion assay\",\n      \"journal\": \"PloS one\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — NMR confirmation of interaction, co-IP, functional perturbation with defined phenotype; single lab\",\n      \"pmids\": [\"37437062\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2025,\n      \"finding\": \"PHLDB2 contains intrinsically disordered regions (IDRs) and forms dynamic, reversible liquid-liquid phase separation (LLPS) condensates, as confirmed by FRAP assays. PHLDB2 knockdown inhibits EMT (upregulates E-cadherin, downregulates N-cadherin, vimentin, Snail, MMP-2), reduces tumor growth, and impairs pulmonary metastasis in TNBC xenograft models.\",\n      \"method\": \"PONDR disorder prediction, FRAP assay, KD/OE in cell lines, in vivo xenograft and metastasis models\",\n      \"journal\": \"Cancer medicine\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2-3 — FRAP confirms LLPS in cells, supported by in vivo KD phenotype; single lab, no reconstitution\",\n      \"pmids\": [\"41319208\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2025,\n      \"finding\": \"LL5β (PHLDB2) cortical patches at the beta cell periphery co-localize with ELKS to define secretion hot spots for directed insulin secretion; however, secretion events occur specifically at the margins of ELKS patches and at cortical sites devoid of microtubules, indicating that local MT disassembly within LL5β/ELKS cortical platforms governs the precise location of insulin secretion.\",\n      \"method\": \"TIRF microscopy of intact mouse islets, live imaging of secretion events relative to ELKS/LL5β patches, MT depolymerization experiments\",\n      \"journal\": \"Molecular biology of the cell\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 — live TIRF imaging in intact tissue with spatial correlation to secretion events; single study\",\n      \"pmids\": [\"40366873\"],\n      \"is_preprint\": false\n    }\n  ],\n  \"current_model\": \"PHLDB2 (LL5β) is a PIP3-sensing scaffold protein whose PH domain binds PtdIns(3,4,5)P3 to direct its cortical recruitment downstream of PI3K signaling, where it assembles multi-protein platforms—including CLASPs, ELKS/ERC1, and filamins—that anchor microtubule plus ends to the cell cortex, regulate focal adhesion disassembly and directed vesicle delivery, organize postsynaptic AChR clusters and LTP-associated receptor trafficking at the NMJ and hippocampal synapses (via PSD-95, GluA1/2, and drebrin A interactions), promote cell migration and EMT (partly through MDM2-mediated E-cadherin degradation and EGFR stabilization), and can undergo liquid-liquid phase separation through intrinsically disordered regions; additionally, PHLDB2 is a direct substrate of the Legionella effector protease Lem8 (activated by host 14-3-3ζ), whose cleavage of PHLDB2 inhibits host cell migration.\"\n}\n```","stage2_raw":"```json\n{\n  \"mechanistic_narrative\": \"PHLDB2 (LL5β) is a PtdIns(3,4,5)P3-sensing scaffold protein that couples PI3K signaling to cortical microtubule capture, focal adhesion dynamics, directed vesicle delivery, and postsynaptic organization. Its C-terminal PH domain selectively binds PIP3 to drive plasma membrane recruitment, where it nucleates cortical platforms containing ELKS/ERC1, CLASPs, and filamins that anchor microtubule plus ends, promote focal adhesion disassembly during cell migration, and define exocytic hot spots for insulin secretion [PMID:12376540, PMID:16824950, PMID:27378169, PMID:40366873]. At the neuromuscular junction and hippocampal synapses, PHLDB2 organizes AChR clustering via CLASP2-dependent vesicle delivery, binds PSD-95 and AMPA receptor subunits to regulate synaptic receptor density, and interacts with drebrin A to control dendritic spine maturation; Phldb2 knockout mice exhibit impaired LTP and memory formation [PMID:25589673, PMID:30867511, PMID:36162735]. PHLDB2 also promotes epithelial–mesenchymal transition by facilitating MDM2-mediated E-cadherin degradation and stabilizing EGFR, and is a direct substrate of the Legionella effector protease Lem8, whose cleavage of PHLDB2 inhibits host cell migration [PMID:31346319, PMID:34952201, PMID:35175192].\",\n  \"teleology\": [\n    {\n      \"year\": 2002,\n      \"claim\": \"Establishing that PHLDB2 is a PIP3-selective lipid-binding protein whose localization is dynamically controlled by PI3K, and that it independently binds γ-filamin, defined its dual identity as a lipid sensor and cytoskeletal adaptor.\",\n      \"evidence\": \"In vitro PIP3 binding with PH domain mutagenesis, PI3K inhibition, co-IP with filamin in mammalian cells\",\n      \"pmids\": [\"12376540\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"No cortical function or downstream effector yet identified\", \"PH domain structure not resolved\", \"Filamin binding significance for cell behavior unknown\"]\n    },\n    {\n      \"year\": 2005,\n      \"claim\": \"Discovery that PHLDB2 localizes to the postsynaptic NMJ membrane and is required for AChR aggregation revealed its first physiological function—organizing postsynaptic receptor clusters.\",\n      \"evidence\": \"Microarray identification, subcellular fractionation, siRNA/dominant-negative perturbation with AChR clustering readout in myotubes\",\n      \"pmids\": [\"15851520\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Mechanism linking PHLDB2 to AChR aggregation unclear\", \"No in vivo NMJ phenotype yet shown\"]\n    },\n    {\n      \"year\": 2006,\n      \"claim\": \"Identification of a cortical LL5β–ELKS–CLASP complex that captures microtubule plus ends at the cell periphery established PHLDB2 as a PIP3-dependent organizer of cortical microtubule anchoring, independent of focal adhesions.\",\n      \"evidence\": \"Mass spectrometry complex identification, reciprocal co-IP, RNAi with live-cell imaging in HeLa cells; domain mapping of filamin C binding with PI3K inhibition\",\n      \"pmids\": [\"16824950\", \"17174070\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Structural basis of LL5β–ELKS and LL5β–CLASP interactions unknown\", \"Functional consequence for cell migration not yet tested\"]\n    },\n    {\n      \"year\": 2010,\n      \"claim\": \"Demonstrating that PIP3-recruited PHLDB2 brings Filamin A and SHIP2 to the leading edge, creating a negative-feedback loop that locally dephosphorylates PIP3, explained how PHLDB2 both responds to and shapes the PIP3 gradient during lamellipodium formation.\",\n      \"evidence\": \"Co-IP, siRNA, PH domain mutagenesis, EGF-stimulated live-cell imaging of lamellipodia\",\n      \"pmids\": [\"20236936\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Quantitative kinetics of feedback loop not measured\", \"Relative contributions of Filamin A vs Filamin C isoforms at the cortex unclear\"]\n    },\n    {\n      \"year\": 2013,\n      \"claim\": \"Identification of PHLDB2 as a component of synaptic podosomes that interacts with actin regulators Amotl2, Asef2, and Flii expanded its role at the NMJ from receptor clustering to active membrane remodeling.\",\n      \"evidence\": \"Affinity purification/MS of LL5β-associated proteins, co-IP, RNAi with podosome morphology readout in myotubes\",\n      \"pmids\": [\"23525008\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Direct vs indirect nature of interactions with Asef2 and Flii not resolved\", \"In vivo relevance for NMJ remodeling not demonstrated\"]\n    },\n    {\n      \"year\": 2014,\n      \"claim\": \"Placing PHLDB2 downstream of BMP2→PI3K(p55γ/p110α) signaling for cortical actin rearrangement and chemotaxis showed it acts as a general effector node for multiple growth factor–PI3K cascades, not only PDGF/EGF.\",\n      \"evidence\": \"MS identification, live-cell imaging, siRNA of p55γ and LL5β, cell migration assays in mesenchymal progenitors\",\n      \"pmids\": [\"24885555\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Whether BMP2 engages the same LL5β–ELKS–CLASP cortical platform not tested\"]\n    },\n    {\n      \"year\": 2015,\n      \"claim\": \"Demonstrating that PHLDB2 is essential for CLASP2-mediated microtubule capture and directed AChR vesicle delivery at the NMJ in vivo, and positioning it in the agrin→PI3K→GSK3β→CLASP2→LL5β pathway, provided a complete signaling axis for postsynaptic receptor maintenance.\",\n      \"evidence\": \"RNAi, dominant-negative CLASP2 fragment, live vesicle imaging, in vivo NMJ analysis in mouse\",\n      \"pmids\": [\"25589673\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Whether other receptor types use the same CLASP2–LL5β delivery route not explored\"]\n    },\n    {\n      \"year\": 2016,\n      \"claim\": \"Connecting the planar cell polarity protein Prickle1 to PHLDB2–CLASP complexes for focal adhesion disassembly during cell retraction revealed how PHLDB2 integrates polarity cues with microtubule-dependent adhesion turnover during migration.\",\n      \"evidence\": \"Reciprocal co-IP, siRNA epistasis, live-cell imaging of focal adhesion disassembly and migration\",\n      \"pmids\": [\"27378169\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Molecular basis of Prickle1–LL5β interaction not mapped\", \"Whether Wnt/PCP signaling directly regulates this complex unclear\"]\n    },\n    {\n      \"year\": 2019,\n      \"claim\": \"Two studies extended PHLDB2's roles to cancer biology and synaptic plasticity: PHLDB2 promotes EMT by facilitating MDM2-mediated E-cadherin degradation in colon cancer, and is required for PSD-95 localization, AMPA receptor density, LTP, and memory in hippocampal synapses.\",\n      \"evidence\": \"Co-IP of PHLDB2–MDM2 with migration/invasion assays; Phldb2 KO mice with LTP electrophysiology, co-IP with PSD-95/GluA1/GluA2, behavioral memory tests\",\n      \"pmids\": [\"31346319\", \"30867511\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"MDM2 interaction awaits reciprocal validation and structural characterization\", \"Relative contributions of PHLDB2's PIP3 binding vs protein scaffolding to synaptic function not separated\"]\n    },\n    {\n      \"year\": 2021,\n      \"claim\": \"Showing that PHLDB2 stabilizes EGFR and promotes its nuclear translocation via a critical Arg1163 contact, and that chemotherapy-induced m6A modification of PHLDB2 mRNA upregulates its expression, identified a new axis for therapy resistance in colorectal cancer.\",\n      \"evidence\": \"MS, proximity ligation assay, co-IP, R1163A mutagenesis, RNA immunoprecipitation for m6A, CRC xenograft models\",\n      \"pmids\": [\"34952201\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Crystal structure of PHLDB2–EGFR interface not available\", \"Whether EGFR stabilization is PIP3-dependent not tested\"]\n    },\n    {\n      \"year\": 2022,\n      \"claim\": \"Identification of PHLDB2 as a direct substrate of the Legionella effector protease Lem8—activated by host 14-3-3ζ—established a pathogen strategy to disable host cell migration by destroying a key cortical scaffold.\",\n      \"evidence\": \"Biochemical protease reconstitution, active-site mutagenesis, co-IP with 14-3-3ζ, cell migration assays\",\n      \"pmids\": [\"35175192\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Cleavage site in PHLDB2 not mapped\", \"Whether Lem8 targets other cortical scaffolds unknown\"]\n    },\n    {\n      \"year\": 2022,\n      \"claim\": \"Discovery of isoform-specific binding between PHLDB2 and drebrin A (but not drebrin E), and the altered spine maturation in Phldb2 KO mice, established PHLDB2 as a regulator of dendritic spine morphogenesis through actin remodeling.\",\n      \"evidence\": \"Isoform-specific co-IP, Phldb2 KO mice with spine morphology analysis in CA1\",\n      \"pmids\": [\"36162735\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Binding interface between PHLDB2 and drebrin A not mapped\", \"Functional relationship to LTP phenotype from prior KO study not tested directly\"]\n    },\n    {\n      \"year\": 2023,\n      \"claim\": \"Mapping the minimal LL5β–ERC1 binding regions to intrinsically disordered segments and showing that disrupting this interaction delocalizes ERC1 and inhibits invadopodium-driven invasion provided structural insight into how the cortical platform assembles.\",\n      \"evidence\": \"NMR spectroscopy, co-IP, fragment expression with live imaging and transwell invasion assay\",\n      \"pmids\": [\"37437062\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Full structural model of LL5β–ERC1 complex not resolved\", \"Whether LLPS contributes to LL5β–ERC1 platform formation not addressed\"]\n    },\n    {\n      \"year\": 2025,\n      \"claim\": \"Two studies revealed that PHLDB2 undergoes liquid-liquid phase separation via its IDRs to promote EMT and metastasis in TNBC, and that LL5β/ELKS cortical patches define insulin secretion hot spots in pancreatic β-cells where local microtubule disassembly permits exocytosis.\",\n      \"evidence\": \"FRAP-confirmed LLPS, KD with in vivo xenograft/metastasis models; TIRF microscopy of secretion events in intact mouse islets\",\n      \"pmids\": [\"41319208\", \"40366873\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"LLPS reconstitution from purified components not performed\", \"Causal link between LL5β LLPS and cortical platform function not established\", \"Mechanism of local MT disassembly at LL5β/ELKS patch margins unclear\"]\n    },\n    {\n      \"year\": null,\n      \"claim\": \"Key unresolved questions include the atomic structure of PHLDB2 and its cortical complex, whether LLPS is functionally required for scaffold assembly, and how PHLDB2's synaptic and migratory functions are differentially regulated in distinct cell types.\",\n      \"evidence\": \"\",\n      \"pmids\": [],\n      \"confidence\": \"High\",\n      \"gaps\": [\"No high-resolution structure of PHLDB2 or any of its complexes\", \"Whether LLPS is a cause or consequence of cortical platform assembly is unknown\", \"Cell-type-specific regulatory mechanisms for PHLDB2 recruitment and function are unexplored\"]\n    }\n  ],\n  \"mechanism_profile\": {\n    \"molecular_activity\": [\n      {\"term_id\": \"GO:0008289\", \"supporting_discovery_ids\": [0, 1, 2]},\n      {\"term_id\": \"GO:0060090\", \"supporting_discovery_ids\": [2, 4, 7, 8]},\n      {\"term_id\": \"GO:0008092\", \"supporting_discovery_ids\": [0, 3, 4, 5]}\n    ],\n    \"localization\": [\n      {\"term_id\": \"GO:0005886\", \"supporting_discovery_ids\": [0, 1, 2, 4, 6, 10, 16]},\n      {\"term_id\": \"GO:0005829\", \"supporting_discovery_ids\": [0, 3]},\n      {\"term_id\": \"GO:0005856\", \"supporting_discovery_ids\": [2, 5, 8]}\n    ],\n    \"pathway\": [\n      {\"term_id\": \"R-HSA-162582\", \"supporting_discovery_ids\": [0, 4, 6, 11]},\n      {\"term_id\": \"R-HSA-1500931\", \"supporting_discovery_ids\": [1, 7, 10]},\n      {\"term_id\": \"R-HSA-112316\", \"supporting_discovery_ids\": [10, 13]},\n      {\"term_id\": \"R-HSA-9609507\", \"supporting_discovery_ids\": [7, 16]}\n    ],\n    \"complexes\": [\n      \"LL5β–ELKS–CLASP cortical platform\"\n    ],\n    \"partners\": [\n      \"ELKS/ERC1\",\n      \"CLASP2\",\n      \"FLNA\",\n      \"FLNC\",\n      \"DLG4\",\n      \"MDM2\",\n      \"EGFR\",\n      \"DBN1\"\n    ],\n    \"other_free_text\": []\n  }\n}\n```"}