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MO25alpha/beta interact with STRADalpha/beta enhancing their ability to bind, activate and localize LKB1 in the cytoplasm.

ABSTRACT: Mutations in the LKB1 protein kinase result in the inherited Peutz Jeghers cancer syndrome. LKB1 has been implicated in regulating cell proliferation and polarity although little is known about how this enzyme is regulated. We recently showed that LKB1 is activated through its interaction with STRADalpha, a catalytically deficient pseudokinase. Here we show that endogenous LKB1-STRADalpha complex is associated with a protein of unknown function, termed MO25alpha, through the interaction of MO25alpha with the last three residues of STRADalpha. MO25alpha and STRADalpha anchor LKB1 in the cytoplasm, excluding it from the nucleus. Moreover, MO25alpha enhances the formation of the LKB1-STRADalpha complex in vivo, stimulating the catalytic activity of LKB1 approximately 10-fold. We demonstrate that the related STRADbeta and MO25beta isoforms are also able to stabilize LKB1 in an active complex and that it is possible to isolate complexes of LKB1 bound to STRAD and MO25 isoforms, in which the subunits are present in equimolar amounts. Our results indicate that MO25 may function as a scaffolding component of the LKB1-STRAD complex and plays a crucial role in regulating LKB1 activity and cellular localization.

SUBMITTER: Boudeau J

PROVIDER: S-EPMC204473 | biostudies-literature | 2003 Oct

REPOSITORIES: biostudies-literature

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MO25alpha/beta interact with STRADalpha/beta enhancing their ability to bind, activate and localize LKB1 in the cytoplasm.

Boudeau Jérôme J Baas Annette F AF Deak Maria M Morrice Nick A NA Kieloch Agnieszka A Schutkowski Mike M Prescott Alan R AR Clevers Hans C HC Alessi Dario R DR

The EMBO journal 20031001 19

Mutations in the LKB1 protein kinase result in the inherited Peutz Jeghers cancer syndrome. LKB1 has been implicated in regulating cell proliferation and polarity although little is known about how this enzyme is regulated. We recently showed that LKB1 is activated through its interaction with STRADalpha, a catalytically deficient pseudokinase. Here we show that endogenous LKB1-STRADalpha complex is associated with a protein of unknown function, termed MO25alpha, through the interaction of MO25a ...[more]

PMID: 14517248

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Project description:BACKGROUND:Although real-time localization of gliomas has improved with intraoperative image guidance systems, these tools are limited by brain shift, surgical cavity deformation, and expense. OBJECTIVE:To propose a novel method to perform near-infrared (NIR) imaging during glioma resections based on preclinical and clinical investigations, in order to localize tumors and to potentially identify residual disease. METHODS:Fifteen patients were identified and administered a Food and Drug Administration-approved, NIR contrast agent (Second Window indocyanine green [ICG], 5 mg/kg) before surgical resection. An NIR camera was utilized to localize the tumor before resection and to visualize surgical margins following resection. Neuropathology and magnetic resonance imaging data were used to assess the accuracy and precision of NIR fluorescence in identifying tumor tissue. RESULTS:NIR visualization of 15 gliomas (10 glioblastoma multiforme, 1 anaplastic astrocytoma, 2 low-grade astrocytoma, 1 juvenile pilocytic astrocytoma, and 1 ganglioglioma) was performed 22.7 hours (mean) after intravenous injection of ICG. During surgery, 12 of 15 tumors were visualized with the NIR camera. The mean signal-to-background ratio was 9.5 ± 0.8 and fluorescence was noted through the dura to a maximum parenchymal depth of 13 mm. The best predictor of positive fluorescence was enhancement on T1-weighted imaging; this correlated with signal-to-background ratio (P = .03). Nonenhancing tumors did not demonstrate NIR fluorescence. Using pathology as the gold standard, the technique demonstrated a sensitivity of 98% and specificity of 45% to identify tumor in gadolinium-enhancing specimens (n = 71). CONCLUSION:With the use of Second Window ICG, gadolinium-enhancing tumors can be localized through brain parenchyma intraoperatively. Its utility for margin detection is promising but limited by lower specificity. ABBREVIATIONS:5-ALA, 5-aminolevulinic acidEPR, enhanced permeability and retentionFDA, Food and Drug AdministrationGBM, glioblastomaICG, indocyanine greenNIR, near-infraredNPV, negative predictive valuePPV, positive predictive valueROC, receiver operating characteristicROI, region of interestSBR, signal-to-background ratioWHO, World Health Organization.

Dataset Information

MO25alpha/beta interact with STRADalpha/beta enhancing their ability to bind, activate and localize LKB1 in the cytoplasm.

Publications

MO25alpha/beta interact with STRADalpha/beta enhancing their ability to bind, activate and localize LKB1 in the cytoplasm.

Similar Datasets

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