| 2003 |
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. |
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 of biology |
High |
14511394
|
| 2003 |
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. |
Co-immunoprecipitation of endogenous complex, in vitro kinase assay, subcellular fractionation/localization, siRNA knockdown with cell-cycle readout, characterization of PJS patient mutation |
The EMBO journal |
High |
12805220
|
| 2004 |
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. |
Inducible STRAD expression in intestinal epithelial cell lines, immunofluorescence, electron microscopy |
Cell |
High |
15016379
|
| 2004 |
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. |
Mutagenesis of 34 LKB1 cancer mutants, Co-IP binding assays, in vitro kinase assay, ATP-binding assays |
Journal of cell science |
High |
15561763
|
| 2005 |
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. |
In vitro kinase assay with recombinant LKB1/STRAD/MO25 and purified rat liver AMPKK, dose-response analysis with palmitoyl-CoA and related lipids |
American journal of physiology. Endocrinology and metabolism |
Medium |
15644453
|
| 2006 |
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. |
In vitro kinase assay with recombinant LKB1-STRAD-MO25 and an array of metabolites |
American journal of physiology. Endocrinology and metabolism |
Medium |
16985256
|
| 2007 |
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. |
siRNA knockdown, overexpression, live imaging in cultured hippocampal neurons and in vivo cortical neurons, phosphorylation analysis |
Cell |
High |
17482549
|
| 2007 |
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. |
SNP microarray autozygosity mapping, copy number analysis, neuropathological examination with immunostaining for phospho-S6 |
Brain : a journal of neurology |
Medium |
17522105
|
| 2008 |
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. |
Immunostaining, FRET, manipulation of E-cadherin junctions, AMPK phosphorylation assay |
Current biology : CB |
Medium |
19110428
|
| 2009 |
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. |
X-ray crystallography of heterotrimeric complex, structural analysis, functional validation of mutations identified in Peutz-Jeghers syndrome and sporadic cancers |
Science (New York, N.Y.) |
High |
19892943
|
| 2009 |
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. |
Co-immunoprecipitation (Mo25α-Mst4 interaction), live-cell imaging of Mst4 translocation, in vitro kinase assay (Mst4 phosphorylating Ezrin T567), inhibitor studies |
Developmental cell |
High |
19386264
|
| 2010 |
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. |
Genetic epistasis in C. elegans (strd-1 and par-4 mutants), AMPK phosphorylation assays, dauer/embryo phenotype analysis |
Development (Cambridge, England) |
High |
20110331
|
| 2013 |
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. |
siRNA knockdown in mouse neural progenitor cells, rapamycin/p70S6Ki rescue experiments in vitro and in vivo (in utero electroporation), patient-derived fibroblast assays |
Science translational medicine |
High |
23616120
|
| 2014 |
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. |
In vivo cortical electroporation, shRNA knockdown of STRADα vs. STRADβ, protein level analysis, subcellular localization studies in developing cortex |
Neural development |
Medium |
24594058
|
| 2022 |
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. |
Co-immunoprecipitation (MDK with LKB1 and STRAD), in vitro kinase assay (LKB1 activity), AMPK phosphorylation assays under glucose starvation/2-DG, cell proliferation assays |
Cell death & disease |
Medium |
35487917
|
| 2022 |
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. |
Medium-throughput screening of STRAD ligands, direct LKB1 kinase activity assays, comparison of direct vs. indirect assessment methods |
Methods in enzymology |
Medium |
35525550
|
| 2020 |
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. |
CRISPR knockout cells, iPSC-derived neurons from PMSE patients, electrophysiology, immunostaining for phospho-S6, histopathology of Strada-/- mouse brain |
Frontiers in cellular neuroscience |
Medium |
32457579
|
| 2033 |
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. |
STRADA knockout human brain organoids (dorsal and ventral forebrain), rapamycin rescue, cell type composition analysis |
Stem cell reports |
Medium |
41791387
|