scholarly journals Wnt Regulation: Exploring Axin-Disheveled interactions and defining mechanisms by which the SCF E3 ubiquitin ligase is recruited to the destruction complex

2019 ◽  
Author(s):  
Kristina N. Schaefer ◽  
Mira Pronobis ◽  
Clara E. Williams ◽  
Shiping Zhang ◽  
Lauren Bauer ◽  
...  
Keyword(s):  
Wnt Signaling ◽  
Ubiquitin Ligase ◽  
Mammalian Cells ◽  
Human Cancer ◽  
E3 Ubiquitin Ligase ◽  
Adult Stem Cell ◽  
Dynamic Component ◽  
Test Models ◽  
Rgs Domain ◽  
Underlying Mechanisms

AbstractWnt signaling plays key roles in embryonic development and adult stem cell homeostasis, and is altered in human cancer. Signaling is turned on and off by regulating stability of the effector β-catenin. The multiprotein destruction complex binds and phosphorylates β-catenin, and transfers it to the SCF-TrCP E3-ubiquitin ligase, for ubiquitination and destruction. Wnt signals act though Dishevelled to turn down the destruction complex, stabilizing β-catenin. Recent work clarified underlying mechanisms, but important questions remain. We explore β-catenin transfer from the destruction complex to the E3 ligase, and test models suggesting Dishevelled and APC2 compete for association with Axin. We find that Slimb/TrCP is a dynamic component of the destruction complex biomolecular condensate, while other E3 proteins are not. Recruitment requires Axin and not APC, and Axin’s RGS domain plays an important role. We find that elevating Dishevelled levels in Drosophila embryos has paradoxical effects, promoting the ability of limiting levels of Axin to turn off Wnt signaling. When we elevate Dishevelled levels, it forms its own cytoplasmic puncta, but these do not recruit Axin. SIM imaging in mammalian cells suggests that this may result by promoting Dishevelled: Dishevelled interactions at the expense of Dishevelled:Axin interactions when Dishevelled levels are high.

scholarly journals Wnt regulation: exploring Axin-Disheveled interactions and defining mechanisms by which the SCF E3 ubiquitin ligase is recruited to the destruction complex

2020 ◽  
Vol 31 (10) ◽  
pp. 992-1014 ◽  
Author(s):  
Kristina N. Schaefer ◽  
Mira I. Pronobis ◽  
Clara E. Williams ◽  
Shiping Zhang ◽  
Lauren Bauer ◽  
...  
Keyword(s):  
Stem Cell ◽  
Embryonic Development ◽  
Wnt Signaling ◽  
Ubiquitin Ligase ◽  
Human Cancer ◽  
E3 Ubiquitin Ligase ◽  
E3 Ligase ◽  
Adult Stem Cell ◽  
Cell Homeostasis ◽  
Test Models

Wnt signaling plays key roles in embryonic development and adult stem cell homeostasis and is altered in human cancer. We explore β-catenin transfer from the destruction complex to the E3 ligase, and test models suggesting Dishevelled and APC2 compete for association with Axin.

scholarly journals Hakai is required for stabilization of core components of the m6A mRNA methylation machinery

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Praveen Bawankar ◽  
Tina Lence ◽  
Chiara Paolantoni ◽  
Irmgard U. Haussmann ◽  
Migle Kazlauskiene ◽  
...  
Keyword(s):  
Catalytic Activity ◽  
Sex Determination ◽  
Ubiquitin Ligase ◽  
Mammalian Cells ◽  
E3 Ubiquitin Ligase ◽  
Human Cells ◽  
Biological Functions ◽  
Mrna Metabolism ◽  
Mrna Methylation ◽  
Core Components

AbstractN6-methyladenosine (m6A) is the most abundant internal modification on mRNA which influences most steps of mRNA metabolism and is involved in several biological functions. The E3 ubiquitin ligase Hakai was previously found in complex with components of the m6A methylation machinery in plants and mammalian cells but its precise function remained to be investigated. Here we show that Hakai is a conserved component of the methyltransferase complex in Drosophila and human cells. In Drosophila, its depletion results in reduced m6A levels and altered m6A-dependent functions including sex determination. We show that its ubiquitination domain is required for dimerization and interaction with other members of the m6A machinery, while its catalytic activity is dispensable. Finally, we demonstrate that the loss of Hakai destabilizes several subunits of the methyltransferase complex, resulting in impaired m6A deposition. Our work adds functional and molecular insights into the mechanism of the m6A mRNA writer complex.

scholarly journals Negative Regulation of CARD11 Signaling and Lymphoma Cell Survival by the E3 Ubiquitin Ligase RNF181

2015 ◽  
Vol 36 (5) ◽  
pp. 794-808 ◽  
Author(s):  
Sarah M. Pedersen ◽  
Waipan Chan ◽  
Rakhi P. Jattani ◽  
deMauri S. Mackie ◽  
Joel L. Pomerantz
Keyword(s):  
Ubiquitin Ligase ◽  
Protein Interactions ◽  
Mammalian Cells ◽  
E3 Ubiquitin Ligase ◽  
Antigen Receptor ◽  
Resonance Energy ◽  
B Cell Lymphoma ◽  
Receptor Signaling ◽  
Antigen Receptor Signaling

NF-κB activation downstream of antigen receptor engagement is a highly regulated event required for lymphocyte activation during the adaptive immune response. The pathway is often dysregulated in lymphoma, leading to constitutive NF-κB activity that supports the aberrant proliferation of transformed lymphocytes. To identify novel regulators of antigen receptor signaling to NF-κB, we developed bioluminescence resonance energy transfer-based interaction cloning (BRIC), a screening strategy that can detect protein-protein interactions in live mammalian cells in a high-throughput manner. Using this strategy, we identified the RING finger protein RNF181 as an interactor of CARD11, a key signaling scaffold in the antigen receptor pathway. We present evidence that RNF181 functions as an E3 ubiquitin ligase to inhibit antigen receptor signaling to NF-κB downstream of CARD11. The levels of the obligate signaling protein Bcl10 are reduced by RNF181 even prior to signaling, and Bcl10 can serve as a substrate for RNF181 E3 ligase activityin vitro. Furthermore, RNF181 limits the proliferation of human diffuse large B cell lymphoma cells that depend upon aberrant CARD11 signaling to NF-κB for growth and survival in culture. Our results define a new regulatory checkpoint that can modulate the output of CARD11 signaling to NF-κB in both normal and transformed lymphocytes.

scholarly journals Mindbomb 1, an E3 ubiquitin ligase, forms a complex with RYK to activate Wnt/β-catenin signaling

2011 ◽  
Vol 194 (5) ◽  
pp. 737-750 ◽  
Author(s):  
Jason D. Berndt ◽  
Atsushi Aoyagi ◽  
Peitzu Yang ◽  
Jamie N. Anastas ◽  
Lan Tang ◽  
...  
Keyword(s):  
Plasma Membrane ◽  
Wnt Signaling ◽  
Ubiquitin Ligase ◽  
Genetic Interaction ◽  
E3 Ubiquitin Ligase ◽  
Secreted Protein ◽  
Loss Of Function ◽  
Protein Ligands ◽  
Steady State Levels ◽  
Novel Targets

Receptor-like tyrosine kinase (RYK) functions as a transmembrane receptor for the Wnt family of secreted protein ligands. Although RYK undergoes endocytosis in response to Wnt, the mechanisms that regulate its internalization and concomitant activation of Wnt signaling are unknown. We discovered that RYK both physically and functionally interacts with the E3 ubiquitin ligase Mindbomb 1 (MIB1). Overexpression of MIB1 promotes the ubiquitination of RYK and reduces its steady-state levels at the plasma membrane. Moreover, we show that MIB1 is sufficient to activate Wnt/β-catenin (CTNNB1) signaling and that this activity depends on endogenous RYK. Conversely, in loss-of-function studies, both RYK and MIB1 are required for Wnt-3A–mediated activation of CTNNB1. Finally, we identify the Caenorhabditis elegans orthologue of MIB1 and demonstrate a genetic interaction between ceMIB and lin-18/RYK in vulva development. These findings provide insights into the mechanisms of Wnt/RYK signaling and point to novel targets for the modulation of Wnt signaling.

scholarly journals Ubiquitin Ligase WWP1 Interacts with Ebola Virus VP40 To Regulate Egress

2017 ◽  
Vol 91 (20) ◽  
Author(s):  
Ziying Han ◽  
Cari A. Sagum ◽  
Fumio Takizawa ◽  
Gordon Ruthel ◽  
Corbett T. Berry ◽  
...  
Keyword(s):  
Ubiquitin Ligase ◽  
Mammalian Cells ◽  
Matrix Protein ◽  
Ebola Virus ◽  
E3 Ubiquitin Ligase ◽  
Hemorrhagic Fever ◽  
Efficient Production ◽  
Ww Domain ◽  
Ww Domains ◽  
E3 Ligases

ABSTRACT Ebola virus (EBOV) is a member of the Filoviridae family and the cause of hemorrhagic fever outbreaks. The EBOV VP40 (eVP40) matrix protein is the main driving force for virion assembly and budding. Indeed, expression of eVP40 alone in mammalian cells results in the formation and budding of virus-like particles (VLPs) which mimic the budding process and morphology of authentic, infectious EBOV. To complete the budding process, eVP40 utilizes its PPXY L-domain motif to recruit a specific subset of host proteins containing one or more modular WW domains that then function to facilitate efficient production and release of eVP40 VLPs. In this report, we identified additional host WW-domain interactors by screening for potential interactions between mammalian proteins possessing one or more WW domains and WT or PPXY mutant peptides of eVP40. We identified the HECT family E3 ubiquitin ligase WWP1 and all four of its WW domains as strong interactors with the PPXY motif of eVP40. The eVP40-WWP1 interaction was confirmed by both peptide pulldown and coimmunoprecipitation assays, which also demonstrated that modular WW domain 1 of WWP1 was most critical for binding to eVP40. Importantly, the eVP40-WWP1 interaction was found to be biologically relevant for VLP budding since (i) small interfering RNA (siRNA) knockdown of endogenous WWP1 resulted in inhibition of eVP40 VLP egress, (ii) coexpression of WWP1 and eVP40 resulted in ubiquitination of eVP40 and a subsequent increase in eVP40 VLP egress, and (iii) an enzymatically inactive mutant of WWP1 (C890A) did not ubiquitinate eVP40 or enhance eVP40 VLP egress. Last, our data show that ubiquitination of eVP40 by WWP1 enhances egress of VLPs and concomitantly decreases cellular levels of higher-molecular-weight oligomers of eVP40. In sum, these findings contribute to our fundamental understanding of the functional interplay between host E3 ligases, ubiquitination, and regulation of EBOV VP40-mediated egress. IMPORTANCE Ebola virus (EBOV) is a high-priority, emerging human pathogen that can cause severe outbreaks of hemorrhagic fever with high mortality rates. As there are currently no approved vaccines or treatments for EBOV, a better understanding of the biology and functions of EBOV-host interactions that promote or inhibit viral budding is warranted. Here, we describe a physical and functional interaction between EBOV VP40 (eVP40) and WWP1, a host E3 ubiquitin ligase that ubiquitinates VP40 and regulates VLP egress. This viral PPXY-host WW domain-mediated interaction represents a potential new target for host-oriented inhibitors of EBOV egress.

scholarly journals SMURF2 phosphorylation at Thr249 modifies the stemness and tumorigenicity of glioma stem cells by regulating TGF-β receptor stability

2021 ◽  
Author(s):  
Manami Hiraiwa ◽  
Kazuya Fukasawa ◽  
Takashi Iezaki ◽  
Hemragul Sabit ◽  
Tetsuhiro Horie ◽  
...  
Keyword(s):  
Stem Cells ◽  
Ubiquitin Ligase ◽  
E3 Ubiquitin Ligase ◽  
Glioma Stem Cells ◽  
Self Renewal ◽  
Ubiquitin Protein Ligase ◽  
Phosphorylation Level ◽  
Ubiquitin Ligase Activity ◽  
Β Receptor ◽  
Underlying Mechanisms

Abstract Glioma stem cells (GSCs) contribute to the pathogenesis of glioblastoma, the most malignant form of glioma. The implication and underlying mechanisms of SMAD specific E3 ubiquitin protein ligase 2 (SMURF2) on the GSC phenotypes remain unknown. We previously demonstrated that SMURF2 phosphorylation at Thr249 (SMURF2Thr249) activates its E3 ubiquitin ligase activity. Here, we demonstrate that SMURF2Thr249 phosphorylation plays an essential role in maintaining GSC stemness and tumorigenicity. SMURF2 silencing augmented the self-renewal potential and tumorgenicity of patient-derived GSCs. The SMURF2Thr249 phosphorylation level was low in human glioblastoma pathology specimens. Introduction of the SMURF2T249A mutant resulted in increased stemness and tumorgenicity of GSCs, recapitulating the SMURF2 silencing. Moreover, the inactivation of SMURF2Thr249 phosphorylation increases TGF-β receptor (TGFBR) protein stability. Indeed, TGFBR1 knockdown markedly counteracted the GSC phenotypes by SMURF2T249A mutant. These findings highlight the importance of SMURF2Thr249 phosphorylation in maintaining GSC phenotypes, thereby demonstrating a potential target for GSC-directed therapy.

scholarly journals SMURF2 phosphorylation at Thr249 modifies the stemness and tumorigenicity of glioma stem cells by regulating TGF-β receptor stability

2021 ◽  
Author(s):  
Manami Hiraiwa ◽  
Kazuya Fukasawa ◽  
Takashi Iezaki ◽  
Hemragul Sabit ◽  
Tetsuhiro Horie ◽  
...  
Keyword(s):  
Stem Cells ◽  
Ubiquitin Ligase ◽  
E3 Ubiquitin Ligase ◽  
Glioma Stem Cells ◽  
Self Renewal ◽  
Ubiquitin Protein Ligase ◽  
Phosphorylation Level ◽  
Ubiquitin Ligase Activity ◽  
Β Receptor ◽  
Underlying Mechanisms

AbstractGlioma stem cells (GSCs) contribute to the pathogenesis of glioblastoma, the most malignant form of glioma. The implication and underlying mechanisms of SMAD specific E3 ubiquitin protein ligase 2 (SMURF2) on the GSC phenotypes remain unknown. We previously demonstrated that SMURF2 phosphorylation at Thr249 (SMURF2Thr249) activates its E3 ubiquitin ligase activity. Here, we demonstrate that SMURF2Thr249 phosphorylation plays an essential role in maintaining GSC stemness and tumorigenicity. SMURF2 silencing augmented the self-renewal potential and tumorgenicity of patient-derived GSCs. The SMURF2Thr249 phosphorylation level was low in human glioblastoma pathology specimens. Introduction of the SMURF2T249A mutant resulted in increased stemness and tumorgenicity of GSCs, recapitulating the SMURF2 silencing. Moreover, the inactivation of SMURF2Thr249 phosphorylation increases TGF-β receptor (TGFBR) protein stability. Indeed, TGFBR1 knockdown markedly counteracted the GSC phenotypes by SMURF2T249A mutant. These findings highlight the importance of SMURF2Thr249 phosphorylation in maintaining GSC phenotypes, thereby demonstrating a potential target for GSC-directed therapy.

Sign in / Sign up

Export Citation Format

Share Document