The Experts below are selected from a list of 1224 Experts worldwide ranked by ideXlab platform
Zhijie Chang - One of the best experts on this subject based on the ideXlab platform.
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dishevelled DEP Domain interacting protein ddip inhibits wnt signaling by promoting tcf4 degradation and disrupting the tcf4 β catenin complex
Cellular Signalling, 2010Co-Authors: Haiwei Zhang, Hui Zhang, Yanquan Zhang, Yingying Wang, Yaqi Duan, Lin Chen, Yonggong Zhai, Ser Sur Ng, Zhijie ChangAbstract:Abstract The TCF4/β-catenin complex, the executor of canonical Wnt/β-catenin signaling, is regulated by a variety of factors. Among these, Dishevelled (Dvl) is a critical regulator that releases β-catenin from degradation and stabilizes TCF4/β-catenin complex. Here, we report that DDIP ( D ishevelled- D EP Domain I nteracting P rotein, also named as Spats1, spermatogenesis associated, serine-rich 1), a novel protein that interacts with Dvl, regulates Wnt signaling. We provide evidence that DDIP suppresses Lef-1 luciferase reporter activity stimulated by Wnt1, Dvl2 or β-catenin, interacts with the TCF4/β-catenin complex, and disrupts the interaction of TCF4 and β-catenin by promoting TCF4 degradation through the proteasome pathway. Our results indicate that DDIP is a negative regulator of the canonical Wnt signaling.
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dishevelled DEP Domain interacting protein ddip inhibits wnt signaling by promoting tcf4 degradation and disrupting the tcf4 β catenin complex
Cellular Signalling, 2010Co-Authors: Haiwei Zhang, Hui Zhang, Yanquan Zhang, Yingying Wang, Yaqi Duan, Lin Chen, Yonggong Zhai, Fangli Ren, Qinglong Guo, Zhijie ChangAbstract:Abstract The TCF4/β-catenin complex, the executor of canonical Wnt/β-catenin signaling, is regulated by a variety of factors. Among these, Dishevelled (Dvl) is a critical regulator that releases β-catenin from degradation and stabilizes TCF4/β-catenin complex. Here, we report that DDIP ( D ishevelled- D EP Domain I nteracting P rotein, also named as Spats1, spermatogenesis associated, serine-rich 1), a novel protein that interacts with Dvl, regulates Wnt signaling. We provide evidence that DDIP suppresses Lef-1 luciferase reporter activity stimulated by Wnt1, Dvl2 or β-catenin, interacts with the TCF4/β-catenin complex, and disrupts the interaction of TCF4 and β-catenin by promoting TCF4 degradation through the proteasome pathway. Our results indicate that DDIP is a negative regulator of the canonical Wnt signaling.
Lin Li - One of the best experts on this subject based on the ideXlab platform.
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the e3 ubiquitin ligase itch negatively regulates canonical wnt signaling by targeting dishevelled protein
Molecular and Cellular Biology, 2012Co-Authors: Meng Li, Jiyong Wang, Lin LiAbstract:Dishevelled (Dvl) is a key component in the canonical Wnt signaling pathway and becomes hyperphosphorylated upon Wnt stimulation. Dvl is required for LRP6 phosphorylation, which is essential for subsequent steps of signal transduction, such as Axin recruitment and cytosolic β-catenin stabilization. Here, we identify the HECT-containing Nedd4-like ubiquitin E3 ligase ITCH as a new Dvl-binding protein. ITCH ubiquitinates the phosphorylated form of Dvl and promotes its degradation via the proteasome pathway, thereby inhibiting canonical Wnt signaling. Knockdown of ITCH by RNA interference increased the stability of phosphorylated Dvl and upregulated Wnt reporter gene activity as well as endogenous Wnt target gene expression induced by Wnt stimulation. In addition, we found that both the PPXY motif and the DEP Domain of Dvl are critical for its interaction with ITCH, as mutation in the PPXY motif (Dvl2-Y568F) or deletion of the DEP Domain led to reduced affinity for ITCH. Consistently, overexpression of ITCH inhibited wild-type Dvl2-induced, but not Dvl2-Y568F mutant-induced, Wnt reporter activity. Moreover, the Y568F mutant, but not wild-type Dvl2, can reverse the ITCH-mediated inhibition of Wnt-induced reporter activity. Collectively, these results indicate that ITCH plays a negative regulatory role in modulating canonical Wnt signaling by targeting the phosphorylated form of Dvl.
Melissa V Gammons - One of the best experts on this subject based on the ideXlab platform.
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regulation of dishevelled DEP Domain swapping by conserved phosphorylation sites
Proceedings of the National Academy of Sciences of the United States of America, 2021Co-Authors: Gonzalo J Beitia, Trevor J Rutherford, Mariann Bienz, Stefan M V Freund, Hugh R B Pelham, Melissa V GammonsAbstract:Wnt signals bind to Frizzled receptors to trigger canonical and noncanonical signaling responses that control cell fates during animal development and tissue homeostasis. All Wnt signals are relayed by the hub protein Dishevelled. During canonical (β-catenin-DEPendent) signaling, Dishevelled assembles signalosomes via dynamic head-to-tail polymerization of its Dishevelled and Axin (DIX) Domain, which are cross-linked by its Dishevelled, Egl-10, and Pleckstrin (DEP) Domain through a conformational switch from monomer to Domain-swapped dimer. The Domain-swapped conformation of DEP masks the site through which Dishevelled binds to Frizzled, implying that DEP Domain swapping results in the detachment of Dishevelled from Frizzled. This would be incompatible with noncanonical Wnt signaling, which relies on long-term association between Dishevelled and Frizzled. It is therefore likely that DEP Domain swapping is differentially regulated during canonical and noncanonical Wnt signaling. Here, we use NMR spectroscopy and cell-based assays to uncover intermolecular contacts in the DEP dimer that are essential for its stability and for Dishevelled function in relaying canonical Wnt signals. These contacts are mediated by an intrinsically structured sequence spanning a conserved phosphorylation site upstream of the DEP Domain that serves to clamp down the swapped N-terminal α-helix onto the structural core of a reciprocal DEP molecule in the Domain-swapped configuration. Mutations of this phosphorylation site and its cognate surface on the reciprocal DEP core attenuate DEP-DEPendent dimerization of Dishevelled and its canonical signaling activity in cells without impeding its binding to Frizzled. We propose that phosphorylation of this crucial residue could be employed to switch off canonical Wnt signaling.
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essential role of the dishevelled DEP Domain in a wnt DEPendent human cell based complementation assay
Journal of Cell Science, 2016Co-Authors: Melissa V Gammons, Trevor J Rutherford, Zachary Steinhart, Stephane Angers, Mariann BienzAbstract:Dishevelled (DVL) assembles Wnt signalosomes through dynamic head-to-tail polymerisation by means of its DIX Domain. It thus transduces Wnt signals to cytoplasmic effectors including β-catenin, to control cell fates during normal development, tissue homeostasis and also in cancer. To date, most functional studies of Dishevelled relied on its Wnt-inDEPendent signalling activity resulting from overexpression, which is sufficient to trigger polymerisation, bypassing the requirement for Wnt signals. Here, we generate a human cell line devoid of endogenous Dishevelled (DVL1– DVL3), which lacks Wnt signal transduction to β-catenin. However, Wnt responses can be restored by DVL2 stably re-expressed at near-endogenous levels. Using this assay to test mutant DVL2, we show that its DEP Domain is essential, whereas its PDZ Domain is dispensable, for signalling to β-catenin. Our results imply two mutually exclusive functions of the DEP Domain in Wnt signal transduction – binding to Frizzled to recruit Dishevelled to the receptor complex, and dimerising to cross-link DIX Domain polymers for signalosome assembly. Our assay avoids the caveats associated with overexpressing Dishevelled, and provides a powerful tool for rigorous functional tests of this pivotal human signalling protein.
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wnt signalosome assembly by DEP Domain swapping of dishevelled
Molecular Cell, 2016Co-Authors: Melissa V Gammons, Miha Renko, Christopher M Johnson, Trevor J Rutherford, Mariann BienzAbstract:Extracellular signals are often transduced by dynamic signaling complexes ("signalosomes") assembled by oligomerizing hub proteins following their recruitment to signal-activated transmembrane receptors. A paradigm is the Wnt signalosome, which is assembled by Dishevelled via reversible head-to-tail polymerization by its DIX Domain. Its activity causes stabilization of β-catenin, a Wnt effector with pivotal roles in animal development and cancer. How Wnt triggers signalosome assembly is unknown. Here, we use structural analysis, as well as biophysical and cell-based assays, to show that the DEP Domain of Dishevelled undergoes a conformational switch, from monomeric to swapped dimer, to trigger DIX-DEPendent polymerization and signaling to β-catenin. This occurs in two steps: binding of monomeric DEP to Frizzled followed by DEP Domain swapping triggered by its high local concentration upon Wnt-induced recruitment into clathrin-coated pits. DEP Domain swapping confers directional bias on signaling, and the dimerization provides cross-linking between Dishevelled polymers, illustrating a key principle underlying signalosome formation.
Saeko Ishida - One of the best experts on this subject based on the ideXlab platform.
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DEPdc5 knockout rat: A novel model of mTORopathy
Neurobiology of Disease, 2016Co-Authors: Elise Marsan, Saeko Ishida, Adrien Schramm, Sarah Weckhuysen, Giuseppe Muraca, Sarah Lecas, Ning Liang, Caroline Treins, Mario Pende, Delphine RousselAbstract:DEP-Domain containing 5 (DEPDC5), encoding a repressor of the mechanistic target of rapamycin complex 1 (mTORC1) signaling pathway, has recently emerged as a major gene mutated in familial focal epilepsies and focal cortical dysplasia. Here we established a global knockout rat using TALEN technology to investigate in vivo the impact of DEPdc5-deficiency. Homozygous DEPdc5−/− embryos died from embryonic day 14.5 due to a global growth delay. Constitutive mTORC1 hyperactivation was evidenced in the brains and in cultured fibroblasts of DEPdc5−/− embryos, as reflected by enhanced phosphorylation of its downstream effectors S6K1 and rpS6. Consistently, prenatal treatment with mTORC1 inhibitor rapamycin rescued the phenotype of DEPdc5−/− embryos. Heterozygous DEPdc5+/− rats developed normally and exhibited no spontaneous electroclinical seizures, but had altered cortical neuron excitability and firing patterns. DEPdc5+/− rats displayed cortical cytomegalic dysmorphic neurons and balloon-like cells strongly expressing phosphorylated rpS6, indicative of mTORC1 upregulation, and not observed after prenatal rapamycin treatment. These neuropathological abnormalities are reminiscent of the hallmark brain pathology of human focal cortical dysplasia. Altogether, DEPdc5 knockout rats exhibit multiple features of rodent models of mTORopathies, and thus, stand as a relevant model to study their underlying pathogenic mechanisms.
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familial focal epilepsy with focal cortical dysplasia due to DEPdc5 mutations
Annals of Neurology, 2015Co-Authors: Stephanie Baulac, Dang Khoa Nguyen, Saeko Ishida, Elise Marsan, Catherine Miquel, Arnaud Biraben, Doug Nordli, Patrick Cossette, Sylvie Nguyen, Virginie LambrecqAbstract:Objective The DEPDC5 (DEP Domain-containing protein 5) gene, encoding a repressor of the mTORC1 signaling pathway, has recently emerged as a major gene mutated in familial focal epilepsies. We aimed to further extend the role of DEPDC5 to focal cortical dysplasias (FCDs). Methods Seven patients from 4 families with DEPDC5 mutations and focal epilepsy associated with FCD were recruited and investigated at the clinical, neuroimaging, and histopathological levels. The DEPDC5 gene was sequenced from genomic blood and brain DNA. Results All patients had drug-resistant focal epilepsy, 5 of them underwent surgery, and 1 had a brain biopsy. Electroclinical phenotypes were compatible with FCD II, although magnetic resonance imaging (MRI) was typical in only 4 cases. Histopathology confirmed FCD IIa in 2 patients (including 1 MRI-negative case) and showed FCD I in 2 other patients, and remained inconclusive in the last 2 patients. Three patients were seizure-free postsurgically, and 1 had a worthwhile improvement. Sequencing of blood DNA revealed truncating DEPDC5 mutations in all 4 families; 1 mutation was found to be mosaic in an asymptomatic father. A brain somatic DEPDC5 mutation was identified in 1 patient in addition to the germline mutation. Interpretation Germline, germline mosaic, and brain somatic DEPDC5 mutations may cause epilepsy associated with FCD, reinforcing the link between mTORC1 pathway and FCDs. Similarly to other mTORopathies, a “2-hit” mutational model could be responsible for cortical lesions. Our study also indicates that epilepsy surgery is a valuable alternative in the treatment of drug-resistant DEPDC5-positive focal epilepsies, even if the MRI is unremarkable.
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Mutations of DEPDC5 cause autosomal dominant focal epilepsies
Nature Genetics, 2013Co-Authors: Saeko Ishida, Fabienne Picard, Gabrielle Rudolf, Eric Noe, Guillaume Achaz, Pierre Thomas, Pierre Genton, Emeline Mundwiller, Markus Wolff, Christian MarescauxAbstract:The main familial focal epilepsies are autosomal dominant nocturnal frontal lobe epilepsy, familial temporal lobe epilepsy and familial focal epilepsy with variable foci. A frameshift mutation in the DEPDC5 gene (encoding DEP Domain-containing protein 5) was identified in a family with focal epilepsy with variable foci by linkage analysis and exome sequencing. Subsequent pyrosequencing of DEPDC5 in a cohort of 15 additional families with focal epilepsies identified 4 nonsense mutations and 1 missense mutation. Our findings provided evidence of frequent (37%) loss-of-function mutations in DEPDC5 associated with a broad spectrum of focal epilepsies. The implication of a DEP (Dishevelled, Egl-10 and Pleckstrin) Domain-containing protein that may be involved in membrane trafficking and/or G protein signaling opens new avenues for research.
Mariann Bienz - One of the best experts on this subject based on the ideXlab platform.
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regulation of dishevelled DEP Domain swapping by conserved phosphorylation sites
Proceedings of the National Academy of Sciences of the United States of America, 2021Co-Authors: Gonzalo J Beitia, Trevor J Rutherford, Mariann Bienz, Stefan M V Freund, Hugh R B Pelham, Melissa V GammonsAbstract:Wnt signals bind to Frizzled receptors to trigger canonical and noncanonical signaling responses that control cell fates during animal development and tissue homeostasis. All Wnt signals are relayed by the hub protein Dishevelled. During canonical (β-catenin-DEPendent) signaling, Dishevelled assembles signalosomes via dynamic head-to-tail polymerization of its Dishevelled and Axin (DIX) Domain, which are cross-linked by its Dishevelled, Egl-10, and Pleckstrin (DEP) Domain through a conformational switch from monomer to Domain-swapped dimer. The Domain-swapped conformation of DEP masks the site through which Dishevelled binds to Frizzled, implying that DEP Domain swapping results in the detachment of Dishevelled from Frizzled. This would be incompatible with noncanonical Wnt signaling, which relies on long-term association between Dishevelled and Frizzled. It is therefore likely that DEP Domain swapping is differentially regulated during canonical and noncanonical Wnt signaling. Here, we use NMR spectroscopy and cell-based assays to uncover intermolecular contacts in the DEP dimer that are essential for its stability and for Dishevelled function in relaying canonical Wnt signals. These contacts are mediated by an intrinsically structured sequence spanning a conserved phosphorylation site upstream of the DEP Domain that serves to clamp down the swapped N-terminal α-helix onto the structural core of a reciprocal DEP molecule in the Domain-swapped configuration. Mutations of this phosphorylation site and its cognate surface on the reciprocal DEP core attenuate DEP-DEPendent dimerization of Dishevelled and its canonical signaling activity in cells without impeding its binding to Frizzled. We propose that phosphorylation of this crucial residue could be employed to switch off canonical Wnt signaling.
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essential role of the dishevelled DEP Domain in a wnt DEPendent human cell based complementation assay
Journal of Cell Science, 2016Co-Authors: Melissa V Gammons, Trevor J Rutherford, Zachary Steinhart, Stephane Angers, Mariann BienzAbstract:Dishevelled (DVL) assembles Wnt signalosomes through dynamic head-to-tail polymerisation by means of its DIX Domain. It thus transduces Wnt signals to cytoplasmic effectors including β-catenin, to control cell fates during normal development, tissue homeostasis and also in cancer. To date, most functional studies of Dishevelled relied on its Wnt-inDEPendent signalling activity resulting from overexpression, which is sufficient to trigger polymerisation, bypassing the requirement for Wnt signals. Here, we generate a human cell line devoid of endogenous Dishevelled (DVL1– DVL3), which lacks Wnt signal transduction to β-catenin. However, Wnt responses can be restored by DVL2 stably re-expressed at near-endogenous levels. Using this assay to test mutant DVL2, we show that its DEP Domain is essential, whereas its PDZ Domain is dispensable, for signalling to β-catenin. Our results imply two mutually exclusive functions of the DEP Domain in Wnt signal transduction – binding to Frizzled to recruit Dishevelled to the receptor complex, and dimerising to cross-link DIX Domain polymers for signalosome assembly. Our assay avoids the caveats associated with overexpressing Dishevelled, and provides a powerful tool for rigorous functional tests of this pivotal human signalling protein.
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wnt signalosome assembly by DEP Domain swapping of dishevelled
Molecular Cell, 2016Co-Authors: Melissa V Gammons, Miha Renko, Christopher M Johnson, Trevor J Rutherford, Mariann BienzAbstract:Extracellular signals are often transduced by dynamic signaling complexes ("signalosomes") assembled by oligomerizing hub proteins following their recruitment to signal-activated transmembrane receptors. A paradigm is the Wnt signalosome, which is assembled by Dishevelled via reversible head-to-tail polymerization by its DIX Domain. Its activity causes stabilization of β-catenin, a Wnt effector with pivotal roles in animal development and cancer. How Wnt triggers signalosome assembly is unknown. Here, we use structural analysis, as well as biophysical and cell-based assays, to show that the DEP Domain of Dishevelled undergoes a conformational switch, from monomeric to swapped dimer, to trigger DIX-DEPendent polymerization and signaling to β-catenin. This occurs in two steps: binding of monomeric DEP to Frizzled followed by DEP Domain swapping triggered by its high local concentration upon Wnt-induced recruitment into clathrin-coated pits. DEP Domain swapping confers directional bias on signaling, and the dimerization provides cross-linking between Dishevelled polymers, illustrating a key principle underlying signalosome formation.