{"gene":"STRADA","run_date":"2026-06-10T10:51:54","timeline":{"discoveries":[{"year":2003,"finding":"STRADA (STRADα/β) forms a complex with LKB1 and MO25α/β that functions as an upstream kinase (AMPKK) activating AMPK by phosphorylating Thr172 of AMPK. Catalytically active LKB1, STRADα or STRADβ, and MO25α or MO25β are all required for full AMPKK activity. The complex was purified from rat liver and shown to immunoprecipitate with anti-LKB1 antibodies.","method":"Biochemical purification from rat liver, immunoprecipitation, in vitro kinase assay, recombinant complex reconstitution, stable expression of wild-type vs. catalytically inactive LKB1 in HeLa cells, LKB1-knockout mouse embryo fibroblasts","journal":"Journal of biology","confidence":"High","confidence_rationale":"Tier 1 / Strong — reconstituted complex in vitro, multiple orthogonal methods (purification, IP, KO cells, rescue), replicated across endogenous and recombinant systems","pmids":["14511394"],"is_preprint":false},{"year":2003,"finding":"STRADA is an LKB1-specific adaptor and pseudokinase (STE20-like kinase domain lacking catalytic residues) that binds LKB1, activates LKB1 kinase activity, and determines subcellular localization of wild-type LKB1 by translocating it from the nucleus to the cytoplasm. Removal of endogenous STRAD by siRNA abrogated LKB1-induced G1 arrest. A Peutz-Jeghers LKB1 mutation that does not compromise LKB1 kinase activity was shown to interfere with LKB1 binding to STRAD.","method":"Co-immunoprecipitation of endogenous complex, in vitro kinase assay, subcellular fractionation/localization, siRNA knockdown with cell-cycle readout, characterization of PJS patient mutation","journal":"The EMBO journal","confidence":"High","confidence_rationale":"Tier 2 / Strong — reciprocal Co-IP, siRNA KD with defined phenotype, localization experiments, multiple orthogonal methods in a single focused study","pmids":["12805220"],"is_preprint":false},{"year":2004,"finding":"Activation of LKB1 by STRAD in single intestinal epithelial cells is sufficient to induce complete apicobasal polarization, including actin remodeling to form an apical brush border, redistribution of junctional proteins ZO-1 and p120, and sorting of apical and basolateral markers — all in the absence of cell-cell contacts.","method":"Inducible STRAD expression in intestinal epithelial cell lines, immunofluorescence, electron microscopy","journal":"Cell","confidence":"High","confidence_rationale":"Tier 2 / Strong — inducible gain-of-function system with multiple cellular readouts, published in Cell with detailed imaging","pmids":["15016379"],"is_preprint":false},{"year":2004,"finding":"Twelve of 34 LKB1 cancer-associated point mutants fail to interact with STRAD-MO25. Two binding sites on opposite surfaces of MO25α are required for assembly of the MO25α-STRADα-LKB1 complex. LKB1 does not require phosphorylation of its own T-loop to be activated by STRADα-MO25α. STRADα, despite being catalytically inactive, binds ATP with high affinity, but this ATP binding is not required for LKB1 activation.","method":"Mutagenesis of 34 LKB1 cancer mutants, Co-IP binding assays, in vitro kinase assay, ATP-binding assays","journal":"Journal of cell science","confidence":"High","confidence_rationale":"Tier 1 / Strong — systematic mutagenesis combined with in vitro kinase assay and binding studies, multiple orthogonal methods","pmids":["15561763"],"is_preprint":false},{"year":2005,"finding":"Long-chain acyl-CoA esters (LCACEs), specifically palmitoyl-CoA, inhibit the AMPKK activity of the recombinant LKB1/STRAD/MO25 complex toward AMPK (Thr172 phosphorylation) in a substrate-specific manner — palmitoyl-CoA paradoxically stimulates LKB1/STRAD/MO25 activity toward the peptide substrate LKBtide but inhibits phosphorylation of full-length AMPK.","method":"In vitro kinase assay with recombinant LKB1/STRAD/MO25 and purified rat liver AMPKK, dose-response analysis with palmitoyl-CoA and related lipids","journal":"American journal of physiology. Endocrinology and metabolism","confidence":"Medium","confidence_rationale":"Tier 1 / Weak — rigorous in vitro reconstitution assay, single lab, substrate-specificity distinction is novel but not independently replicated","pmids":["15644453"],"is_preprint":false},{"year":2006,"finding":"3-phosphoglycerate (3-PG) stimulates LKB1-STRAD-MO25 AMPKK activity toward AMPK (but not toward the peptide substrate LKBtide), increasing AMPK phosphorylation in vitro. ADP inhibits both AMPK activity and LKB1-STRAD-MO25 activity.","method":"In vitro kinase assay with recombinant LKB1-STRAD-MO25 and an array of metabolites","journal":"American journal of physiology. Endocrinology and metabolism","confidence":"Medium","confidence_rationale":"Tier 1 / Weak — rigorous in vitro reconstitution, single lab, substrate-specific regulation established biochemically","pmids":["16985256"],"is_preprint":false},{"year":2007,"finding":"Accumulation of LKB1 and STRAD in an undifferentiated neurite of cultured hippocampal neurons correlates with subsequent axon differentiation. Downregulation of STRAD by siRNA prevents axon differentiation; overexpression leads to multiple axon formation. STRAD interaction with LKB1 promotes LKB1 phosphorylation at a PKA site (S431) and elevates LKB1 protein levels.","method":"siRNA knockdown, overexpression, live imaging in cultured hippocampal neurons and in vivo cortical neurons, phosphorylation analysis","journal":"Cell","confidence":"High","confidence_rationale":"Tier 2 / Strong — loss-of-function (siRNA) and gain-of-function (OE) with specific morphological readout, in vitro and in vivo validation, multiple orthogonal methods","pmids":["17482549"],"is_preprint":false},{"year":2007,"finding":"Homozygous deletion of exons 9-13 of LYK5/STRADA (encoding a pseudokinase necessary for proper localization and function of LKB1) causes PMSE syndrome (polyhydramnios, megalencephaly, symptomatic epilepsy) with constitutive activation of the mTOR signaling pathway in brain, as evidenced by abundant anti-phospho-ribosomal S6 labeling in affected neurons.","method":"SNP microarray autozygosity mapping, copy number analysis, neuropathological examination with immunostaining for phospho-S6","journal":"Brain : a journal of neurology","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — genetic deletion mapped and mTOR pathway activation confirmed by phospho-S6 IHC in patient tissue; mechanistic link inferred from human genetics plus biomarker staining","pmids":["17522105"],"is_preprint":false},{"year":2008,"finding":"Active LKB1/STRAD kinase complex colocalizes with E-cadherin at adherens junctions (AJs) in polarized epithelial cells, as shown by immunostaining and FRET. LKB1/STRAD localization and AMPK phosphorylation require E-cadherin-dependent maturation of AJs, but LKB1/STRAD complex kinase activity itself is E-cadherin independent, indicating that E-cadherin regulates AMPK phosphorylation by controlling LKB1/STRAD localization.","method":"Immunostaining, FRET, manipulation of E-cadherin junctions, AMPK phosphorylation assay","journal":"Current biology : CB","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — FRET and immunostaining for localization with functional AMPK phosphorylation readout, two orthogonal methods, single lab","pmids":["19110428"],"is_preprint":false},{"year":2009,"finding":"Crystal structure of the core LKB1-STRADα-MO25α heterotrimer reveals an allosteric mechanism of LKB1 activation: STRADα adopts a closed conformation typical of active kinases and binds LKB1 as a pseudosubstrate; STRADα and MO25α promote the active conformation of LKB1; MO25α stabilizes the active conformation by interacting with the LKB1 activation loop. This activation is phosphorylation-independent.","method":"X-ray crystallography of heterotrimeric complex, structural analysis, functional validation of mutations identified in Peutz-Jeghers syndrome and sporadic cancers","journal":"Science (New York, N.Y.)","confidence":"High","confidence_rationale":"Tier 1 / Strong — crystal structure with functional validation of disease mutations, mechanistic model supported by structural and biochemical data in a high-impact journal","pmids":["19892943"],"is_preprint":false},{"year":2009,"finding":"Mo25α interacts with the serine/threonine kinase Mst4 downstream of the LKB1/Strad/Mo25 complex. Upon LKB1 activation, Mst4 translocates from the Golgi to the subapical membrane compartment. Mst4 phosphorylates the regulatory T567 residue of Ezrin, and inhibition of Mst4 blocks LKB1-induced brush border formation (but not lateral junction formation), defining a brush border induction pathway downstream of LKB1/Strad/Mo25.","method":"Co-immunoprecipitation (Mo25α-Mst4 interaction), live-cell imaging of Mst4 translocation, in vitro kinase assay (Mst4 phosphorylating Ezrin T567), inhibitor studies","journal":"Developmental cell","confidence":"High","confidence_rationale":"Tier 1-2 / Strong — Co-IP plus in vitro kinase assay plus live imaging plus inhibitor phenotype, multiple orthogonal methods, clear pathway placement","pmids":["19386264"],"is_preprint":false},{"year":2010,"finding":"In C. elegans, strd-1/STRAD is required for PAR-4/LKB1 to phosphorylate and activate AMPK to regulate germline stem cell quiescence and cell growth/proliferation. However, PAR-4-mediated phosphorylation of polarity regulators PAR-1 and MEX-5 in the early embryo occurs independently of STRD-1, demonstrating that LKB1's polarity function in early embryogenesis is STRAD-independent.","method":"Genetic epistasis in C. elegans (strd-1 and par-4 mutants), AMPK phosphorylation assays, dauer/embryo phenotype analysis","journal":"Development (Cambridge, England)","confidence":"High","confidence_rationale":"Tier 2 / Strong — genetic epistasis with multiple pathway readouts, clear STRAD-dependent vs. independent functions distinguished, replicated across developmental contexts","pmids":["20110331"],"is_preprint":false},{"year":2013,"finding":"STRADA depletion causes constitutive mTORC1 activation and impairs neural progenitor cell migration in vitro. Rapamycin (mTORC1 inhibitor) or p70S6K inhibitor rescues the migration defect. Rapamycin also rescues aberrant cortical lamination and heterotopia in STRADA-depleted mouse cerebral cortex. Constitutive mTORC1 signaling and migration defects were confirmed in fibroblasts from PMSE patients.","method":"siRNA knockdown in mouse neural progenitor cells, rapamycin/p70S6Ki rescue experiments in vitro and in vivo (in utero electroporation), patient-derived fibroblast assays","journal":"Science translational medicine","confidence":"High","confidence_rationale":"Tier 2 / Strong — loss-of-function KD with defined cellular phenotype, pharmacological rescue in vitro and in vivo, patient cell validation — multiple orthogonal approaches","pmids":["23616120"],"is_preprint":false},{"year":2014,"finding":"Both STRADα and STRADβ are sufficient for axogenesis in developing cortical neurons. STRADα specifically maintains LKB1 protein stability via cytoplasmic compartmentalization in vivo — a reciprocal protein-stabilizing relationship between LKB1 and STRADα. STRADβ does not share this stabilization function.","method":"In vivo cortical electroporation, shRNA knockdown of STRADα vs. STRADβ, protein level analysis, subcellular localization studies in developing cortex","journal":"Neural development","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — in vivo KD with defined phenotype and protein stability readout, distinguishes paralog-specific functions, single lab","pmids":["24594058"],"is_preprint":false},{"year":2022,"finding":"Intracellular midkine (MDK) interacts with LKB1 and STRAD to disrupt the LKB1-STRAD-Mo25 complex, thereby decreasing LKB1 activity and dampening both basal and stress-induced AMPK activation (by glucose starvation or 2-DG treatment), promoting cancer cell proliferation.","method":"Co-immunoprecipitation (MDK with LKB1 and STRAD), in vitro kinase assay (LKB1 activity), AMPK phosphorylation assays under glucose starvation/2-DG, cell proliferation assays","journal":"Cell death & disease","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — Co-IP plus kinase assay plus functional proliferation readout, single lab, two orthogonal methods","pmids":["35487917"],"is_preprint":false},{"year":2022,"finding":"Small molecules targeting the ATP-binding pocket of the STRAD pseudokinase can allosterically modulate LKB1 kinase activity, demonstrating that STRAD's ATP-binding site is a tractable allosteric regulatory site for the LKB1-STRAD-MO25 complex.","method":"Medium-throughput screening of STRAD ligands, direct LKB1 kinase activity assays, comparison of direct vs. indirect assessment methods","journal":"Methods in enzymology","confidence":"Medium","confidence_rationale":"Tier 1 / Weak — in vitro kinase assay with direct measurement, single lab, methodology paper with limited mechanistic depth reported in abstract","pmids":["35525550"],"is_preprint":false},{"year":2020,"finding":"STRADA knockout (CRISPR) in mouse N2a cells leads to enhanced mTOR signaling. iPSC-derived neurons from PMSE individuals (STRADA founder mutation) exhibit enhanced cell size and mTOR signaling activation, increased input resistance, more depolarized resting membrane potential, decreased threshold for action potential generation, and ectopic neurons in white matter of Strada-/- mice.","method":"CRISPR knockout cells, iPSC-derived neurons from PMSE patients, electrophysiology, immunostaining for phospho-S6, histopathology of Strada-/- mouse brain","journal":"Frontiers in cellular neuroscience","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — multiple experimental platforms (CRISPR, iPSC, mouse KO) with defined cellular phenotypes, single lab, convergent findings","pmids":["32457579"],"is_preprint":false},{"year":2033,"finding":"STRADA loss (knockout organoids) causes delayed forebrain neurogenesis with progenitor renewal, increased proliferation, expanded outer radial glia, and shifted interneuron subtypes toward neuropeptide-Y-expressing cells. Rapamycin rescues most phenotypes, placing STRADA upstream of mTORC1 in controlling cell fate specification in dorsal and ventral forebrain development.","method":"STRADA knockout human brain organoids (dorsal and ventral forebrain), rapamycin rescue, cell type composition analysis","journal":"Stem cell reports","confidence":"Medium","confidence_rationale":"Tier 2 / Moderate — KO organoid model with multiple cell-type readouts and pharmacological rescue, single lab, peer-reviewed","pmids":["41791387"],"is_preprint":false}],"current_model":"STRADA (STRADα) is a catalytically inactive STE20-like pseudokinase that forms a heterotrimeric complex with the LKB1 tumor suppressor kinase and the scaffolding protein MO25; within this complex, STRADA allosterically activates LKB1 (via a closed pseudosubstrate conformation stabilized by MO25 interactions with the LKB1 activation loop, without requiring phosphorylation), translocates LKB1 from nucleus to cytoplasm, and stabilizes LKB1 protein levels, enabling LKB1 to phosphorylate and activate AMPK and related kinases, thereby regulating cellular energy sensing, epithelial apicobasal polarity, axon initiation, and — via suppression of mTORC1 — neural progenitor proliferation and cortical development."},"narrative":{"mechanistic_narrative":"STRADA (STRADα) is a catalytically inactive STE20-like pseudokinase that serves as the obligate adaptor for the LKB1 tumor suppressor kinase, assembling with LKB1 and the scaffold MO25 into a heterotrimeric complex that functions as the upstream AMPK kinase (AMPKK), phosphorylating AMPK at Thr172 [PMID:14511394, PMID:12805220]. Within this complex STRADA binds LKB1 as a pseudosubstrate in a closed, active-kinase-like conformation, and together with MO25 — which contacts the LKB1 activation loop — allosterically drives LKB1 into its active state without requiring T-loop phosphorylation [PMID:15561763, PMID:19892943]. STRADA also dictates LKB1 subcellular distribution, translocating it from the nucleus to the cytoplasm, and stabilizes LKB1 protein levels through cytoplasmic compartmentalization, a function specific to the α paralog [PMID:12805220, PMID:17482549, PMID:24594058]. Through activated LKB1, STRADA governs diverse processes: it is sufficient to drive complete apicobasal polarization of single epithelial cells including apical brush-border formation [PMID:15016379], with E-cadherin-dependent adherens junctions positioning the LKB1/STRAD complex to license AMPK phosphorylation [PMID:19110428] and a downstream MO25α–Mst4–Ezrin axis executing brush-border induction [PMID:19386264]; it is required for axon specification in cortical neurons [PMID:17482549, PMID:24594058]; and it restrains mTORC1 signaling to control neural progenitor proliferation, migration, and cortical development [PMID:17522105, PMID:23616120]. Homozygous deletion of STRADA causes PMSE syndrome (polyhydramnios, megalencephaly, symptomatic epilepsy), driven by constitutive mTORC1 activation that is pharmacologically reversible with rapamycin [PMID:17522105, PMID:23616120].","teleology":[{"year":2003,"claim":"Established that STRADA is not a free-standing enzyme but a required subunit of the long-sought upstream AMPK kinase, defining its core biochemical role.","evidence":"Biochemical purification from rat liver, reconstitution of recombinant LKB1/STRAD/MO25, in vitro kinase assays, and LKB1-knockout MEFs","pmids":["14511394","12805220"],"confidence":"High","gaps":["Did not resolve how a catalytically dead pseudokinase activates LKB1","Physiological inputs controlling complex activity not yet defined"]},{"year":2003,"claim":"Identified STRADA as an LKB1-specific pseudokinase adaptor that controls LKB1 nuclear-cytoplasmic localization and is required for LKB1-induced G1 arrest, linking complex assembly to tumor suppression.","evidence":"Reciprocal Co-IP of endogenous complex, subcellular fractionation, siRNA knockdown with cell-cycle readout, and a Peutz-Jeghers LKB1 binding mutant","pmids":["12805220"],"confidence":"High","gaps":["Structural basis of LKB1 activation unknown","Mechanism of nuclear export not defined"]},{"year":2004,"claim":"Showed STRADA-driven LKB1 activation is sufficient to polarize single epithelial cells, establishing the complex as a cell-autonomous master regulator of apicobasal polarity independent of cell-cell contact.","evidence":"Inducible STRAD expression in intestinal epithelial lines with immunofluorescence and electron microscopy","pmids":["15016379"],"confidence":"High","gaps":["Downstream effectors of polarization not identified at this stage","Role of AMPK vs other LKB1 substrates unresolved"]},{"year":2004,"claim":"Defined the assembly logic of the complex and demonstrated that LKB1 activation is phosphorylation-independent and that STRADA ATP binding, though high affinity, is dispensable for activation.","evidence":"Systematic mutagenesis of 34 LKB1 cancer mutants, Co-IP binding assays, in vitro kinase assays, and ATP-binding assays","pmids":["15561763"],"confidence":"High","gaps":["Function of STRADA ATP binding left unexplained","Atomic basis of two-site MO25 interaction not yet visualized"]},{"year":2005,"claim":"Began to define metabolic regulation of the complex, showing acyl-CoA lipids modulate AMPKK activity in a substrate-specific manner.","evidence":"In vitro kinase assays with recombinant complex and dose-response analysis of palmitoyl-CoA","pmids":["15644453"],"confidence":"Medium","gaps":["Substrate-specific lipid effect not independently replicated","Physiological relevance in cells not established"]},{"year":2006,"claim":"Extended metabolic regulation by showing glycolytic intermediates and ADP tune complex activity toward AMPK, linking energy state to LKB1/STRAD/MO25 output.","evidence":"In vitro kinase assays with recombinant complex against an array of metabolites","pmids":["16985256"],"confidence":"Medium","gaps":["In vitro only; cellular metabolite sensing not demonstrated","Single lab"]},{"year":2007,"claim":"Demonstrated a neuronal role for STRADA in axon specification and showed it stabilizes LKB1 protein and promotes its phosphorylation, connecting complex assembly to neurodevelopment.","evidence":"siRNA knockdown and overexpression with live imaging in hippocampal and cortical neurons plus phosphorylation analysis","pmids":["17482549"],"confidence":"High","gaps":["Mechanism linking LKB1 stabilization to axogenesis not fully defined","Relevant downstream LKB1 substrate kinases in neurons not pinpointed here"]},{"year":2007,"claim":"Connected STRADA loss to human disease, identifying homozygous LYK5/STRADA deletion as the cause of PMSE syndrome with constitutive brain mTOR activation.","evidence":"Autozygosity mapping, copy number analysis, and phospho-S6 immunostaining of patient neuropathology","pmids":["17522105"],"confidence":"Medium","gaps":["Causal mechanism inferred from genetics plus biomarker, not yet a defined molecular pathway","Link between LKB1/AMPK axis and mTOR hyperactivation not directly demonstrated in this study"]},{"year":2008,"claim":"Resolved how localization couples to function, showing E-cadherin-dependent junction maturation positions the LKB1/STRAD complex to enable AMPK phosphorylation while complex activity itself is junction-independent.","evidence":"Immunostaining, FRET, and E-cadherin junction manipulation with AMPK phosphorylation readout","pmids":["19110428"],"confidence":"Medium","gaps":["Molecular tether linking STRAD complex to adherens junctions not identified","Single lab"]},{"year":2009,"claim":"Provided the structural mechanism: the LKB1-STRADα-MO25α crystal structure showed STRADα adopts a closed conformation and binds LKB1 as a pseudosubstrate, with MO25α stabilizing LKB1's active state phosphorylation-independently.","evidence":"X-ray crystallography of the heterotrimer with functional validation of Peutz-Jeghers and cancer mutations","pmids":["19892943"],"confidence":"High","gaps":["Conformational dynamics and substrate handoff to AMPK not captured","How metabolic ligands feed into this architecture unresolved"]},{"year":2009,"claim":"Mapped a polarity effector branch, defining a MO25α-Mst4-Ezrin axis downstream of the complex that specifically drives brush-border formation.","evidence":"Co-IP, live-cell imaging of Mst4 translocation, in vitro Ezrin T567 kinase assay, and inhibitor phenotyping","pmids":["19386264"],"confidence":"High","gaps":["How LKB1 activation triggers Mst4 relocalization not fully defined","Separation from lateral junction pathway only partially explained"]},{"year":2010,"claim":"Used genetic epistasis in C. elegans to dissect which LKB1 functions require STRADA, showing the AMPK/quiescence arm is STRAD-dependent while early-embryo polarity is STRAD-independent.","evidence":"Genetic epistasis of strd-1 and par-4 mutants with AMPK phosphorylation and developmental phenotype analysis","pmids":["20110331"],"confidence":"High","gaps":["Molecular basis for STRAD-independent LKB1 polarity activity unknown","Mammalian generality of this division not tested here"]},{"year":2013,"claim":"Established that STRADA loss causes constitutive mTORC1 activation and neural progenitor migration/lamination defects that are pharmacologically reversible, defining the actionable disease mechanism of PMSE.","evidence":"siRNA knockdown in neural progenitors, rapamycin/p70S6K-inhibitor rescue in vitro and in utero, and PMSE patient fibroblast validation","pmids":["23616120"],"confidence":"High","gaps":["Precise step from LKB1/AMPK loss to mTORC1 hyperactivation not mechanistically dissected","Long-term in vivo therapeutic outcomes not addressed"]},{"year":2014,"claim":"Distinguished paralog-specific roles, showing both STRADα and STRADβ support axogenesis but only STRADα maintains LKB1 stability via cytoplasmic compartmentalization.","evidence":"In vivo cortical electroporation with shRNA against STRADα vs STRADβ and protein/localization analysis","pmids":["24594058"],"confidence":"Medium","gaps":["Structural basis of the α-specific stabilization not defined","Single lab"]},{"year":2022,"claim":"Identified a physiological regulator that disrupts the complex, with intracellular midkine binding LKB1 and STRAD to dismantle the heterotrimer and blunt AMPK activation in cancer cells.","evidence":"Co-IP of MDK with LKB1 and STRAD, LKB1 in vitro kinase assays, AMPK phosphorylation under glucose starvation/2-DG, and proliferation assays","pmids":["35487917"],"confidence":"Medium","gaps":["Binding interface and stoichiometry of MDK disruption not resolved","Single lab, not independently replicated"]},{"year":2022,"claim":"Demonstrated druggability, showing small molecules occupying the STRAD pseudokinase ATP pocket allosterically modulate LKB1 activity.","evidence":"Medium-throughput ligand screening with direct LKB1 kinase activity assays","pmids":["35525550"],"confidence":"Medium","gaps":["No high-affinity lead or structural binding mode reported","Cellular and in vivo activity not shown"]},{"year":2033,"claim":"Extended the developmental mTORC1 link to human tissue, showing STRADA loss perturbs forebrain neurogenesis and interneuron fate in a rapamycin-reversible manner.","evidence":"STRADA knockout human dorsal and ventral forebrain organoids with rapamycin rescue and cell-type composition analysis","pmids":["41791387"],"confidence":"Medium","gaps":["Cell-type-specific effectors downstream of mTORC1 not defined","Single model system"]},{"year":null,"claim":"How metabolic ligand sensing, junction localization, and physiological complex-disruptors are integrated to set LKB1 output in different tissues, and whether STRAD-pocket ligands can therapeutically tune LKB1/mTORC1 in disease, remains unresolved.","evidence":"","pmids":[],"confidence":"Medium","gaps":["No unified model linking metabolite regulation to in vivo physiology","Therapeutic translation of allosteric STRAD ligands unproven"]}],"mechanism_profile":{"molecular_activity":[{"term_id":"GO:0140096","term_label":"catalytic activity, acting on a protein","supporting_discovery_ids":[0,1,3,9]},{"term_id":"GO:0098772","term_label":"molecular function regulator activity","supporting_discovery_ids":[1,3,9,13]},{"term_id":"GO:0060090","term_label":"molecular adaptor activity","supporting_discovery_ids":[1,9]},{"term_id":"GO:0140657","term_label":"ATP-dependent activity","supporting_discovery_ids":[3,15]}],"localization":[{"term_id":"GO:0005829","term_label":"cytosol","supporting_discovery_ids":[1,13]},{"term_id":"GO:0005634","term_label":"nucleus","supporting_discovery_ids":[1]},{"term_id":"GO:0005886","term_label":"plasma membrane","supporting_discovery_ids":[8,10]}],"pathway":[{"term_id":"R-HSA-8953897","term_label":"Cellular responses to stimuli","supporting_discovery_ids":[0,5]},{"term_id":"R-HSA-1266738","term_label":"Developmental Biology","supporting_discovery_ids":[2,6,12,17]},{"term_id":"R-HSA-162582","term_label":"Signal Transduction","supporting_discovery_ids":[7,12,16]},{"term_id":"R-HSA-1430728","term_label":"Metabolism","supporting_discovery_ids":[4,5]}],"complexes":["LKB1-STRAD-MO25 heterotrimer"],"partners":["STK11","CAB39","MARK3","MDK","STRADB"],"other_free_text":[]}},"prefetch_data":{"uniprot":{"accession":"Q7RTN6","full_name":"STE20-related kinase adapter protein alpha","aliases":["STE20-related adapter protein","Serologically defined breast cancer antigen NY-BR-96"],"length_aa":431,"mass_kda":48.4,"function":"Pseudokinase which, in complex with CAB39/MO25 (CAB39/MO25alpha or CAB39L/MO25beta), binds to and activates STK11/LKB1. Adopts a closed conformation typical of active protein kinases and binds STK11/LKB1 as a pseudosubstrate, promoting conformational change of STK11/LKB1 in an active conformation","subcellular_location":"Nucleus; Cytoplasm","url":"https://www.uniprot.org/uniprotkb/Q7RTN6/entry"},"depmap":{"release":"DepMap","has_data":true,"is_common_essential":false,"resolved_as":"","url":"https://depmap.org/portal/gene/STRADA","classification":"Not Classified","n_dependent_lines":18,"n_total_lines":1208,"dependency_fraction":0.014900662251655629},"opencell":{"profiled":false,"resolved_as":"","ensg_id":"","cell_line_id":"","localizations":[],"interactors":[{"gene":"STK11","stoichiometry":10.0},{"gene":"CLASP2","stoichiometry":0.2}],"url":"https://opencell.sf.czbiohub.org/search/STRADA","total_profiled":1310},"omim":[{"mim_id":"611087","title":"POLYHYDRAMNIOS, MEGALENCEPHALY, AND SYMPTOMATIC EPILEPSY; PMSE","url":"https://www.omim.org/entry/611087"},{"mim_id":"608626","title":"STE20-RELATED KINASE ADAPTOR ALPHA; STRADA","url":"https://www.omim.org/entry/608626"},{"mim_id":"603448","title":"DAB ADAPTOR PROTEIN 1; DAB1","url":"https://www.omim.org/entry/603448"},{"mim_id":"602580","title":"GOLGIN A2; GOLGA2","url":"https://www.omim.org/entry/602580"},{"mim_id":"602255","title":"SERINE/THREONINE PROTEIN KINASE 25; STK25","url":"https://www.omim.org/entry/602255"}],"hpa":{"profiled":true,"resolved_as":"","reliability":"Supported","locations":[{"location":"Nucleoplasm","reliability":"Supported"},{"location":"Cytosol","reliability":"Supported"}],"tissue_specificity":"Low tissue specificity","tissue_distribution":"Detected in all","driving_tissues":[],"url":"https://www.proteinatlas.org/search/STRADA"},"hgnc":{"alias_symbol":["STLK5","NY-BR-96","LYK5","Stlk","STRAD"],"prev_symbol":[]},"alphafold":{"accession":"Q7RTN6","domains":[{"cath_id":"3.30.200.20","chopping":"8-18_63-150","consensus_level":"medium","plddt":92.7843,"start":8,"end":150},{"cath_id":"1.10.510.10","chopping":"154-312_344-403","consensus_level":"high","plddt":93.9914,"start":154,"end":403}],"viewer_url":"https://alphafold.ebi.ac.uk/entry/Q7RTN6","model_url":"https://alphafold.ebi.ac.uk/files/AF-Q7RTN6-F1-model_v6.cif","pae_url":"https://alphafold.ebi.ac.uk/files/AF-Q7RTN6-F1-predicted_aligned_error_v6.png","plddt_mean":80.0},"mouse_models":{"mgi_url":"https://www.informatics.jax.org/marker/summary?nomen=STRADA","jax_strain_url":"https://www.jax.org/strain/search?query=STRADA"},"sequence":{"accession":"Q7RTN6","fasta_url":"https://rest.uniprot.org/uniprotkb/Q7RTN6.fasta","uniprot_url":"https://www.uniprot.org/uniprotkb/Q7RTN6/entry","alphafold_viewer_url":"https://alphafold.ebi.ac.uk/entry/Q7RTN6"}},"corpus_meta":[{"pmid":"14511394","id":"PMC_14511394","title":"Complexes between the LKB1 tumor suppressor, STRAD alpha/beta and MO25 alpha/beta are upstream kinases in the AMP-activated protein kinase cascade.","date":"2003","source":"Journal of biology","url":"https://pubmed.ncbi.nlm.nih.gov/14511394","citation_count":1343,"is_preprint":false},{"pmid":"15016379","id":"PMC_15016379","title":"Complete polarization of single intestinal epithelial cells upon activation of LKB1 by STRAD.","date":"2004","source":"Cell","url":"https://pubmed.ncbi.nlm.nih.gov/15016379","citation_count":422,"is_preprint":false},{"pmid":"12805220","id":"PMC_12805220","title":"Activation of the tumour suppressor kinase LKB1 by the STE20-like pseudokinase STRAD.","date":"2003","source":"The EMBO journal","url":"https://pubmed.ncbi.nlm.nih.gov/12805220","citation_count":308,"is_preprint":false},{"pmid":"17482549","id":"PMC_17482549","title":"LKB1/STRAD promotes axon initiation during neuronal polarization.","date":"2007","source":"Cell","url":"https://pubmed.ncbi.nlm.nih.gov/17482549","citation_count":290,"is_preprint":false},{"pmid":"19892943","id":"PMC_19892943","title":"Structure of the LKB1-STRAD-MO25 complex reveals an allosteric mechanism of kinase activation.","date":"2009","source":"Science (New York, N.Y.)","url":"https://pubmed.ncbi.nlm.nih.gov/19892943","citation_count":285,"is_preprint":false},{"pmid":"19386264","id":"PMC_19386264","title":"Mst4 and Ezrin induce brush borders downstream of the Lkb1/Strad/Mo25 polarization complex.","date":"2009","source":"Developmental cell","url":"https://pubmed.ncbi.nlm.nih.gov/19386264","citation_count":133,"is_preprint":false},{"pmid":"15561763","id":"PMC_15561763","title":"Analysis of the LKB1-STRAD-MO25 complex.","date":"2004","source":"Journal of cell science","url":"https://pubmed.ncbi.nlm.nih.gov/15561763","citation_count":129,"is_preprint":false},{"pmid":"17522105","id":"PMC_17522105","title":"Polyhydramnios, megalencephaly and symptomatic epilepsy caused by a homozygous 7-kilobase deletion in LYK5.","date":"2007","source":"Brain : a journal of neurology","url":"https://pubmed.ncbi.nlm.nih.gov/17522105","citation_count":103,"is_preprint":false},{"pmid":"23616120","id":"PMC_23616120","title":"Rapamycin prevents seizures after depletion of STRADA in a rare neurodevelopmental disorder.","date":"2013","source":"Science translational medicine","url":"https://pubmed.ncbi.nlm.nih.gov/23616120","citation_count":102,"is_preprint":false},{"pmid":"19110428","id":"PMC_19110428","title":"Regulation of LKB1/STRAD localization and function by E-cadherin.","date":"2008","source":"Current biology : CB","url":"https://pubmed.ncbi.nlm.nih.gov/19110428","citation_count":61,"is_preprint":false},{"pmid":"15644453","id":"PMC_15644453","title":"Long-chain acyl-CoA esters inhibit phosphorylation of AMP-activated protein kinase at threonine-172 by LKB1/STRAD/MO25.","date":"2005","source":"American journal of physiology. 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Catalytically active LKB1, STRADα or STRADβ, and MO25α or MO25β are all required for full AMPKK activity. The complex was purified from rat liver and shown to immunoprecipitate with anti-LKB1 antibodies.\",\n      \"method\": \"Biochemical purification from rat liver, immunoprecipitation, in vitro kinase assay, recombinant complex reconstitution, stable expression of wild-type vs. catalytically inactive LKB1 in HeLa cells, LKB1-knockout mouse embryo fibroblasts\",\n      \"journal\": \"Journal of biology\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Strong — reconstituted complex in vitro, multiple orthogonal methods (purification, IP, KO cells, rescue), replicated across endogenous and recombinant systems\",\n      \"pmids\": [\"14511394\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2003,\n      \"finding\": \"STRADA is an LKB1-specific adaptor and pseudokinase (STE20-like kinase domain lacking catalytic residues) that binds LKB1, activates LKB1 kinase activity, and determines subcellular localization of wild-type LKB1 by translocating it from the nucleus to the cytoplasm. Removal of endogenous STRAD by siRNA abrogated LKB1-induced G1 arrest. A Peutz-Jeghers LKB1 mutation that does not compromise LKB1 kinase activity was shown to interfere with LKB1 binding to STRAD.\",\n      \"method\": \"Co-immunoprecipitation of endogenous complex, in vitro kinase assay, subcellular fractionation/localization, siRNA knockdown with cell-cycle readout, characterization of PJS patient mutation\",\n      \"journal\": \"The EMBO journal\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — reciprocal Co-IP, siRNA KD with defined phenotype, localization experiments, multiple orthogonal methods in a single focused study\",\n      \"pmids\": [\"12805220\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2004,\n      \"finding\": \"Activation of LKB1 by STRAD in single intestinal epithelial cells is sufficient to induce complete apicobasal polarization, including actin remodeling to form an apical brush border, redistribution of junctional proteins ZO-1 and p120, and sorting of apical and basolateral markers — all in the absence of cell-cell contacts.\",\n      \"method\": \"Inducible STRAD expression in intestinal epithelial cell lines, immunofluorescence, electron microscopy\",\n      \"journal\": \"Cell\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — inducible gain-of-function system with multiple cellular readouts, published in Cell with detailed imaging\",\n      \"pmids\": [\"15016379\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2004,\n      \"finding\": \"Twelve of 34 LKB1 cancer-associated point mutants fail to interact with STRAD-MO25. Two binding sites on opposite surfaces of MO25α are required for assembly of the MO25α-STRADα-LKB1 complex. LKB1 does not require phosphorylation of its own T-loop to be activated by STRADα-MO25α. STRADα, despite being catalytically inactive, binds ATP with high affinity, but this ATP binding is not required for LKB1 activation.\",\n      \"method\": \"Mutagenesis of 34 LKB1 cancer mutants, Co-IP binding assays, in vitro kinase assay, ATP-binding assays\",\n      \"journal\": \"Journal of cell science\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Strong — systematic mutagenesis combined with in vitro kinase assay and binding studies, multiple orthogonal methods\",\n      \"pmids\": [\"15561763\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2005,\n      \"finding\": \"Long-chain acyl-CoA esters (LCACEs), specifically palmitoyl-CoA, inhibit the AMPKK activity of the recombinant LKB1/STRAD/MO25 complex toward AMPK (Thr172 phosphorylation) in a substrate-specific manner — palmitoyl-CoA paradoxically stimulates LKB1/STRAD/MO25 activity toward the peptide substrate LKBtide but inhibits phosphorylation of full-length AMPK.\",\n      \"method\": \"In vitro kinase assay with recombinant LKB1/STRAD/MO25 and purified rat liver AMPKK, dose-response analysis with palmitoyl-CoA and related lipids\",\n      \"journal\": \"American journal of physiology. Endocrinology and metabolism\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 1 / Weak — rigorous in vitro reconstitution assay, single lab, substrate-specificity distinction is novel but not independently replicated\",\n      \"pmids\": [\"15644453\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2006,\n      \"finding\": \"3-phosphoglycerate (3-PG) stimulates LKB1-STRAD-MO25 AMPKK activity toward AMPK (but not toward the peptide substrate LKBtide), increasing AMPK phosphorylation in vitro. ADP inhibits both AMPK activity and LKB1-STRAD-MO25 activity.\",\n      \"method\": \"In vitro kinase assay with recombinant LKB1-STRAD-MO25 and an array of metabolites\",\n      \"journal\": \"American journal of physiology. Endocrinology and metabolism\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 1 / Weak — rigorous in vitro reconstitution, single lab, substrate-specific regulation established biochemically\",\n      \"pmids\": [\"16985256\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2007,\n      \"finding\": \"Accumulation of LKB1 and STRAD in an undifferentiated neurite of cultured hippocampal neurons correlates with subsequent axon differentiation. Downregulation of STRAD by siRNA prevents axon differentiation; overexpression leads to multiple axon formation. STRAD interaction with LKB1 promotes LKB1 phosphorylation at a PKA site (S431) and elevates LKB1 protein levels.\",\n      \"method\": \"siRNA knockdown, overexpression, live imaging in cultured hippocampal neurons and in vivo cortical neurons, phosphorylation analysis\",\n      \"journal\": \"Cell\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — loss-of-function (siRNA) and gain-of-function (OE) with specific morphological readout, in vitro and in vivo validation, multiple orthogonal methods\",\n      \"pmids\": [\"17482549\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2007,\n      \"finding\": \"Homozygous deletion of exons 9-13 of LYK5/STRADA (encoding a pseudokinase necessary for proper localization and function of LKB1) causes PMSE syndrome (polyhydramnios, megalencephaly, symptomatic epilepsy) with constitutive activation of the mTOR signaling pathway in brain, as evidenced by abundant anti-phospho-ribosomal S6 labeling in affected neurons.\",\n      \"method\": \"SNP microarray autozygosity mapping, copy number analysis, neuropathological examination with immunostaining for phospho-S6\",\n      \"journal\": \"Brain : a journal of neurology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — genetic deletion mapped and mTOR pathway activation confirmed by phospho-S6 IHC in patient tissue; mechanistic link inferred from human genetics plus biomarker staining\",\n      \"pmids\": [\"17522105\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2008,\n      \"finding\": \"Active LKB1/STRAD kinase complex colocalizes with E-cadherin at adherens junctions (AJs) in polarized epithelial cells, as shown by immunostaining and FRET. LKB1/STRAD localization and AMPK phosphorylation require E-cadherin-dependent maturation of AJs, but LKB1/STRAD complex kinase activity itself is E-cadherin independent, indicating that E-cadherin regulates AMPK phosphorylation by controlling LKB1/STRAD localization.\",\n      \"method\": \"Immunostaining, FRET, manipulation of E-cadherin junctions, AMPK phosphorylation assay\",\n      \"journal\": \"Current biology : CB\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — FRET and immunostaining for localization with functional AMPK phosphorylation readout, two orthogonal methods, single lab\",\n      \"pmids\": [\"19110428\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2009,\n      \"finding\": \"Crystal structure of the core LKB1-STRADα-MO25α heterotrimer reveals an allosteric mechanism of LKB1 activation: STRADα adopts a closed conformation typical of active kinases and binds LKB1 as a pseudosubstrate; STRADα and MO25α promote the active conformation of LKB1; MO25α stabilizes the active conformation by interacting with the LKB1 activation loop. This activation is phosphorylation-independent.\",\n      \"method\": \"X-ray crystallography of heterotrimeric complex, structural analysis, functional validation of mutations identified in Peutz-Jeghers syndrome and sporadic cancers\",\n      \"journal\": \"Science (New York, N.Y.)\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1 / Strong — crystal structure with functional validation of disease mutations, mechanistic model supported by structural and biochemical data in a high-impact journal\",\n      \"pmids\": [\"19892943\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2009,\n      \"finding\": \"Mo25α interacts with the serine/threonine kinase Mst4 downstream of the LKB1/Strad/Mo25 complex. Upon LKB1 activation, Mst4 translocates from the Golgi to the subapical membrane compartment. Mst4 phosphorylates the regulatory T567 residue of Ezrin, and inhibition of Mst4 blocks LKB1-induced brush border formation (but not lateral junction formation), defining a brush border induction pathway downstream of LKB1/Strad/Mo25.\",\n      \"method\": \"Co-immunoprecipitation (Mo25α-Mst4 interaction), live-cell imaging of Mst4 translocation, in vitro kinase assay (Mst4 phosphorylating Ezrin T567), inhibitor studies\",\n      \"journal\": \"Developmental cell\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 1-2 / Strong — Co-IP plus in vitro kinase assay plus live imaging plus inhibitor phenotype, multiple orthogonal methods, clear pathway placement\",\n      \"pmids\": [\"19386264\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2010,\n      \"finding\": \"In C. elegans, strd-1/STRAD is required for PAR-4/LKB1 to phosphorylate and activate AMPK to regulate germline stem cell quiescence and cell growth/proliferation. However, PAR-4-mediated phosphorylation of polarity regulators PAR-1 and MEX-5 in the early embryo occurs independently of STRD-1, demonstrating that LKB1's polarity function in early embryogenesis is STRAD-independent.\",\n      \"method\": \"Genetic epistasis in C. elegans (strd-1 and par-4 mutants), AMPK phosphorylation assays, dauer/embryo phenotype analysis\",\n      \"journal\": \"Development (Cambridge, England)\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — genetic epistasis with multiple pathway readouts, clear STRAD-dependent vs. independent functions distinguished, replicated across developmental contexts\",\n      \"pmids\": [\"20110331\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2013,\n      \"finding\": \"STRADA depletion causes constitutive mTORC1 activation and impairs neural progenitor cell migration in vitro. Rapamycin (mTORC1 inhibitor) or p70S6K inhibitor rescues the migration defect. Rapamycin also rescues aberrant cortical lamination and heterotopia in STRADA-depleted mouse cerebral cortex. Constitutive mTORC1 signaling and migration defects were confirmed in fibroblasts from PMSE patients.\",\n      \"method\": \"siRNA knockdown in mouse neural progenitor cells, rapamycin/p70S6Ki rescue experiments in vitro and in vivo (in utero electroporation), patient-derived fibroblast assays\",\n      \"journal\": \"Science translational medicine\",\n      \"confidence\": \"High\",\n      \"confidence_rationale\": \"Tier 2 / Strong — loss-of-function KD with defined cellular phenotype, pharmacological rescue in vitro and in vivo, patient cell validation — multiple orthogonal approaches\",\n      \"pmids\": [\"23616120\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2014,\n      \"finding\": \"Both STRADα and STRADβ are sufficient for axogenesis in developing cortical neurons. STRADα specifically maintains LKB1 protein stability via cytoplasmic compartmentalization in vivo — a reciprocal protein-stabilizing relationship between LKB1 and STRADα. STRADβ does not share this stabilization function.\",\n      \"method\": \"In vivo cortical electroporation, shRNA knockdown of STRADα vs. STRADβ, protein level analysis, subcellular localization studies in developing cortex\",\n      \"journal\": \"Neural development\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — in vivo KD with defined phenotype and protein stability readout, distinguishes paralog-specific functions, single lab\",\n      \"pmids\": [\"24594058\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2022,\n      \"finding\": \"Intracellular midkine (MDK) interacts with LKB1 and STRAD to disrupt the LKB1-STRAD-Mo25 complex, thereby decreasing LKB1 activity and dampening both basal and stress-induced AMPK activation (by glucose starvation or 2-DG treatment), promoting cancer cell proliferation.\",\n      \"method\": \"Co-immunoprecipitation (MDK with LKB1 and STRAD), in vitro kinase assay (LKB1 activity), AMPK phosphorylation assays under glucose starvation/2-DG, cell proliferation assays\",\n      \"journal\": \"Cell death & disease\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — Co-IP plus kinase assay plus functional proliferation readout, single lab, two orthogonal methods\",\n      \"pmids\": [\"35487917\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2022,\n      \"finding\": \"Small molecules targeting the ATP-binding pocket of the STRAD pseudokinase can allosterically modulate LKB1 kinase activity, demonstrating that STRAD's ATP-binding site is a tractable allosteric regulatory site for the LKB1-STRAD-MO25 complex.\",\n      \"method\": \"Medium-throughput screening of STRAD ligands, direct LKB1 kinase activity assays, comparison of direct vs. indirect assessment methods\",\n      \"journal\": \"Methods in enzymology\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 1 / Weak — in vitro kinase assay with direct measurement, single lab, methodology paper with limited mechanistic depth reported in abstract\",\n      \"pmids\": [\"35525550\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2020,\n      \"finding\": \"STRADA knockout (CRISPR) in mouse N2a cells leads to enhanced mTOR signaling. iPSC-derived neurons from PMSE individuals (STRADA founder mutation) exhibit enhanced cell size and mTOR signaling activation, increased input resistance, more depolarized resting membrane potential, decreased threshold for action potential generation, and ectopic neurons in white matter of Strada-/- mice.\",\n      \"method\": \"CRISPR knockout cells, iPSC-derived neurons from PMSE patients, electrophysiology, immunostaining for phospho-S6, histopathology of Strada-/- mouse brain\",\n      \"journal\": \"Frontiers in cellular neuroscience\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — multiple experimental platforms (CRISPR, iPSC, mouse KO) with defined cellular phenotypes, single lab, convergent findings\",\n      \"pmids\": [\"32457579\"],\n      \"is_preprint\": false\n    },\n    {\n      \"year\": 2033,\n      \"finding\": \"STRADA loss (knockout organoids) causes delayed forebrain neurogenesis with progenitor renewal, increased proliferation, expanded outer radial glia, and shifted interneuron subtypes toward neuropeptide-Y-expressing cells. Rapamycin rescues most phenotypes, placing STRADA upstream of mTORC1 in controlling cell fate specification in dorsal and ventral forebrain development.\",\n      \"method\": \"STRADA knockout human brain organoids (dorsal and ventral forebrain), rapamycin rescue, cell type composition analysis\",\n      \"journal\": \"Stem cell reports\",\n      \"confidence\": \"Medium\",\n      \"confidence_rationale\": \"Tier 2 / Moderate — KO organoid model with multiple cell-type readouts and pharmacological rescue, single lab, peer-reviewed\",\n      \"pmids\": [\"41791387\"],\n      \"is_preprint\": false\n    }\n  ],\n  \"current_model\": \"STRADA (STRADα) is a catalytically inactive STE20-like pseudokinase that forms a heterotrimeric complex with the LKB1 tumor suppressor kinase and the scaffolding protein MO25; within this complex, STRADA allosterically activates LKB1 (via a closed pseudosubstrate conformation stabilized by MO25 interactions with the LKB1 activation loop, without requiring phosphorylation), translocates LKB1 from nucleus to cytoplasm, and stabilizes LKB1 protein levels, enabling LKB1 to phosphorylate and activate AMPK and related kinases, thereby regulating cellular energy sensing, epithelial apicobasal polarity, axon initiation, and — via suppression of mTORC1 — neural progenitor proliferation and cortical development.\"\n}\n```","stage2_raw":"{\n  \"mechanistic_narrative\": \"STRADA (STRADα) is a catalytically inactive STE20-like pseudokinase that serves as the obligate adaptor for the LKB1 tumor suppressor kinase, assembling with LKB1 and the scaffold MO25 into a heterotrimeric complex that functions as the upstream AMPK kinase (AMPKK), phosphorylating AMPK at Thr172 [#0, #1]. Within this complex STRADA binds LKB1 as a pseudosubstrate in a closed, active-kinase-like conformation, and together with MO25 — which contacts the LKB1 activation loop — allosterically drives LKB1 into its active state without requiring T-loop phosphorylation [#3, #9]. STRADA also dictates LKB1 subcellular distribution, translocating it from the nucleus to the cytoplasm, and stabilizes LKB1 protein levels through cytoplasmic compartmentalization, a function specific to the α paralog [#1, #6, #13]. Through activated LKB1, STRADA governs diverse processes: it is sufficient to drive complete apicobasal polarization of single epithelial cells including apical brush-border formation [#2], with E-cadherin-dependent adherens junctions positioning the LKB1/STRAD complex to license AMPK phosphorylation [#8] and a downstream MO25α–Mst4–Ezrin axis executing brush-border induction [#10]; it is required for axon specification in cortical neurons [#6, #13]; and it restrains mTORC1 signaling to control neural progenitor proliferation, migration, and cortical development [#7, #12]. Homozygous deletion of STRADA causes PMSE syndrome (polyhydramnios, megalencephaly, symptomatic epilepsy), driven by constitutive mTORC1 activation that is pharmacologically reversible with rapamycin [#7, #12].\",\n  \"teleology\": [\n    {\n      \"year\": 2003,\n      \"claim\": \"Established that STRADA is not a free-standing enzyme but a required subunit of the long-sought upstream AMPK kinase, defining its core biochemical role.\",\n      \"evidence\": \"Biochemical purification from rat liver, reconstitution of recombinant LKB1/STRAD/MO25, in vitro kinase assays, and LKB1-knockout MEFs\",\n      \"pmids\": [\"14511394\", \"12805220\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Did not resolve how a catalytically dead pseudokinase activates LKB1\", \"Physiological inputs controlling complex activity not yet defined\"]\n    },\n    {\n      \"year\": 2003,\n      \"claim\": \"Identified STRADA as an LKB1-specific pseudokinase adaptor that controls LKB1 nuclear-cytoplasmic localization and is required for LKB1-induced G1 arrest, linking complex assembly to tumor suppression.\",\n      \"evidence\": \"Reciprocal Co-IP of endogenous complex, subcellular fractionation, siRNA knockdown with cell-cycle readout, and a Peutz-Jeghers LKB1 binding mutant\",\n      \"pmids\": [\"12805220\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Structural basis of LKB1 activation unknown\", \"Mechanism of nuclear export not defined\"]\n    },\n    {\n      \"year\": 2004,\n      \"claim\": \"Showed STRADA-driven LKB1 activation is sufficient to polarize single epithelial cells, establishing the complex as a cell-autonomous master regulator of apicobasal polarity independent of cell-cell contact.\",\n      \"evidence\": \"Inducible STRAD expression in intestinal epithelial lines with immunofluorescence and electron microscopy\",\n      \"pmids\": [\"15016379\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Downstream effectors of polarization not identified at this stage\", \"Role of AMPK vs other LKB1 substrates unresolved\"]\n    },\n    {\n      \"year\": 2004,\n      \"claim\": \"Defined the assembly logic of the complex and demonstrated that LKB1 activation is phosphorylation-independent and that STRADA ATP binding, though high affinity, is dispensable for activation.\",\n      \"evidence\": \"Systematic mutagenesis of 34 LKB1 cancer mutants, Co-IP binding assays, in vitro kinase assays, and ATP-binding assays\",\n      \"pmids\": [\"15561763\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Function of STRADA ATP binding left unexplained\", \"Atomic basis of two-site MO25 interaction not yet visualized\"]\n    },\n    {\n      \"year\": 2005,\n      \"claim\": \"Began to define metabolic regulation of the complex, showing acyl-CoA lipids modulate AMPKK activity in a substrate-specific manner.\",\n      \"evidence\": \"In vitro kinase assays with recombinant complex and dose-response analysis of palmitoyl-CoA\",\n      \"pmids\": [\"15644453\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Substrate-specific lipid effect not independently replicated\", \"Physiological relevance in cells not established\"]\n    },\n    {\n      \"year\": 2006,\n      \"claim\": \"Extended metabolic regulation by showing glycolytic intermediates and ADP tune complex activity toward AMPK, linking energy state to LKB1/STRAD/MO25 output.\",\n      \"evidence\": \"In vitro kinase assays with recombinant complex against an array of metabolites\",\n      \"pmids\": [\"16985256\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"In vitro only; cellular metabolite sensing not demonstrated\", \"Single lab\"]\n    },\n    {\n      \"year\": 2007,\n      \"claim\": \"Demonstrated a neuronal role for STRADA in axon specification and showed it stabilizes LKB1 protein and promotes its phosphorylation, connecting complex assembly to neurodevelopment.\",\n      \"evidence\": \"siRNA knockdown and overexpression with live imaging in hippocampal and cortical neurons plus phosphorylation analysis\",\n      \"pmids\": [\"17482549\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Mechanism linking LKB1 stabilization to axogenesis not fully defined\", \"Relevant downstream LKB1 substrate kinases in neurons not pinpointed here\"]\n    },\n    {\n      \"year\": 2007,\n      \"claim\": \"Connected STRADA loss to human disease, identifying homozygous LYK5/STRADA deletion as the cause of PMSE syndrome with constitutive brain mTOR activation.\",\n      \"evidence\": \"Autozygosity mapping, copy number analysis, and phospho-S6 immunostaining of patient neuropathology\",\n      \"pmids\": [\"17522105\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Causal mechanism inferred from genetics plus biomarker, not yet a defined molecular pathway\", \"Link between LKB1/AMPK axis and mTOR hyperactivation not directly demonstrated in this study\"]\n    },\n    {\n      \"year\": 2008,\n      \"claim\": \"Resolved how localization couples to function, showing E-cadherin-dependent junction maturation positions the LKB1/STRAD complex to enable AMPK phosphorylation while complex activity itself is junction-independent.\",\n      \"evidence\": \"Immunostaining, FRET, and E-cadherin junction manipulation with AMPK phosphorylation readout\",\n      \"pmids\": [\"19110428\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Molecular tether linking STRAD complex to adherens junctions not identified\", \"Single lab\"]\n    },\n    {\n      \"year\": 2009,\n      \"claim\": \"Provided the structural mechanism: the LKB1-STRADα-MO25α crystal structure showed STRADα adopts a closed conformation and binds LKB1 as a pseudosubstrate, with MO25α stabilizing LKB1's active state phosphorylation-independently.\",\n      \"evidence\": \"X-ray crystallography of the heterotrimer with functional validation of Peutz-Jeghers and cancer mutations\",\n      \"pmids\": [\"19892943\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Conformational dynamics and substrate handoff to AMPK not captured\", \"How metabolic ligands feed into this architecture unresolved\"]\n    },\n    {\n      \"year\": 2009,\n      \"claim\": \"Mapped a polarity effector branch, defining a MO25α-Mst4-Ezrin axis downstream of the complex that specifically drives brush-border formation.\",\n      \"evidence\": \"Co-IP, live-cell imaging of Mst4 translocation, in vitro Ezrin T567 kinase assay, and inhibitor phenotyping\",\n      \"pmids\": [\"19386264\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"How LKB1 activation triggers Mst4 relocalization not fully defined\", \"Separation from lateral junction pathway only partially explained\"]\n    },\n    {\n      \"year\": 2010,\n      \"claim\": \"Used genetic epistasis in C. elegans to dissect which LKB1 functions require STRADA, showing the AMPK/quiescence arm is STRAD-dependent while early-embryo polarity is STRAD-independent.\",\n      \"evidence\": \"Genetic epistasis of strd-1 and par-4 mutants with AMPK phosphorylation and developmental phenotype analysis\",\n      \"pmids\": [\"20110331\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Molecular basis for STRAD-independent LKB1 polarity activity unknown\", \"Mammalian generality of this division not tested here\"]\n    },\n    {\n      \"year\": 2013,\n      \"claim\": \"Established that STRADA loss causes constitutive mTORC1 activation and neural progenitor migration/lamination defects that are pharmacologically reversible, defining the actionable disease mechanism of PMSE.\",\n      \"evidence\": \"siRNA knockdown in neural progenitors, rapamycin/p70S6K-inhibitor rescue in vitro and in utero, and PMSE patient fibroblast validation\",\n      \"pmids\": [\"23616120\"],\n      \"confidence\": \"High\",\n      \"gaps\": [\"Precise step from LKB1/AMPK loss to mTORC1 hyperactivation not mechanistically dissected\", \"Long-term in vivo therapeutic outcomes not addressed\"]\n    },\n    {\n      \"year\": 2014,\n      \"claim\": \"Distinguished paralog-specific roles, showing both STRADα and STRADβ support axogenesis but only STRADα maintains LKB1 stability via cytoplasmic compartmentalization.\",\n      \"evidence\": \"In vivo cortical electroporation with shRNA against STRADα vs STRADβ and protein/localization analysis\",\n      \"pmids\": [\"24594058\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Structural basis of the α-specific stabilization not defined\", \"Single lab\"]\n    },\n    {\n      \"year\": 2022,\n      \"claim\": \"Identified a physiological regulator that disrupts the complex, with intracellular midkine binding LKB1 and STRAD to dismantle the heterotrimer and blunt AMPK activation in cancer cells.\",\n      \"evidence\": \"Co-IP of MDK with LKB1 and STRAD, LKB1 in vitro kinase assays, AMPK phosphorylation under glucose starvation/2-DG, and proliferation assays\",\n      \"pmids\": [\"35487917\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Binding interface and stoichiometry of MDK disruption not resolved\", \"Single lab, not independently replicated\"]\n    },\n    {\n      \"year\": 2022,\n      \"claim\": \"Demonstrated druggability, showing small molecules occupying the STRAD pseudokinase ATP pocket allosterically modulate LKB1 activity.\",\n      \"evidence\": \"Medium-throughput ligand screening with direct LKB1 kinase activity assays\",\n      \"pmids\": [\"35525550\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"No high-affinity lead or structural binding mode reported\", \"Cellular and in vivo activity not shown\"]\n    },\n    {\n      \"year\": 2033,\n      \"claim\": \"Extended the developmental mTORC1 link to human tissue, showing STRADA loss perturbs forebrain neurogenesis and interneuron fate in a rapamycin-reversible manner.\",\n      \"evidence\": \"STRADA knockout human dorsal and ventral forebrain organoids with rapamycin rescue and cell-type composition analysis\",\n      \"pmids\": [\"41791387\"],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"Cell-type-specific effectors downstream of mTORC1 not defined\", \"Single model system\"]\n    },\n    {\n      \"year\": null,\n      \"claim\": \"How metabolic ligand sensing, junction localization, and physiological complex-disruptors are integrated to set LKB1 output in different tissues, and whether STRAD-pocket ligands can therapeutically tune LKB1/mTORC1 in disease, remains unresolved.\",\n      \"evidence\": \"\",\n      \"pmids\": [],\n      \"confidence\": \"Medium\",\n      \"gaps\": [\"No unified model linking metabolite regulation to in vivo physiology\", \"Therapeutic translation of allosteric STRAD ligands unproven\"]\n    }\n  ],\n  \"mechanism_profile\": {\n    \"molecular_activity\": [\n      {\"term_id\": \"GO:0140096\", \"supporting_discovery_ids\": [0, 1, 3, 9]},\n      {\"term_id\": \"GO:0098772\", \"supporting_discovery_ids\": [1, 3, 9, 13]},\n      {\"term_id\": \"GO:0060090\", \"supporting_discovery_ids\": [1, 9]},\n      {\"term_id\": \"GO:0140657\", \"supporting_discovery_ids\": [3, 15]}\n    ],\n    \"localization\": [\n      {\"term_id\": \"GO:0005829\", \"supporting_discovery_ids\": [1, 13]},\n      {\"term_id\": \"GO:0005634\", \"supporting_discovery_ids\": [1]},\n      {\"term_id\": \"GO:0005886\", \"supporting_discovery_ids\": [8, 10]}\n    ],\n    \"pathway\": [\n      {\"term_id\": \"R-HSA-8953897\", \"supporting_discovery_ids\": [0, 5]},\n      {\"term_id\": \"R-HSA-1266738\", \"supporting_discovery_ids\": [2, 6, 12, 17]},\n      {\"term_id\": \"R-HSA-162582\", \"supporting_discovery_ids\": [7, 12, 16]},\n      {\"term_id\": \"R-HSA-1430728\", \"supporting_discovery_ids\": [4, 5]}\n    ],\n    \"complexes\": [\"LKB1-STRAD-MO25 heterotrimer\"],\n    \"partners\": [\"STK11\", \"CAB39\", \"MARK3\", \"MDK\", \"STRADB\"],\n    \"other_free_text\": []\n  }\n}","audit_flag":null,"evaluation":{"pairwise":"win","faith_supported":5,"faith_total":5,"faith_pct":100.0}}