scholarly journals ANKIB1 Functions as a Partner of E3 ubiquitin ligase 

2021 ◽  
Author(s):  
Bohong Xie ◽  
Zhenling Ma ◽  
Zishan Yang ◽  
Yuanbo Li ◽  
Shirao Liu ◽  
...  
Keyword(s):  
Ubiquitin Ligase ◽  
Cellular Localization ◽  
Brain Cortex ◽  
Human Cancer ◽  
Expression Patterns ◽  
E3 Ubiquitin Ligase ◽  
E3 Ligase ◽  
Protein Ubiquitination

Abstract ANKIB1 is an RBR domain-containing protein. It has been classified as an E3 ubiquitin ligase for a long time. However, little is known about its E3 ligase activity and related ubiquitin-conjugating enzymes (E2s). We investigated the expression pattern, cellular localization, and brain distribution of ANKIB1. Immunoblotting showed that human cancer cell lines had different expression patterns of ANKIB1 with virus-transformed immortal lymphocytes and human brain. Immunocytofluorescence analysis indicated that ANKIB1 was mainly localized in the cytoplasm, and immunohistochemistry staining demonstrated that ANKIB1 was highly expressed in the rat brain cortex but seldom expressed in the basal ganglia. We then performed coimmunoprecipitation, in vitro and in vivo ubiquitination assay to determine whether ANKIB1 functions as an E3 ligase. A panel of class I and class III E2s were tested, of which UbcH8, UbcH10, and UbcH13 were confirmed to interact with ANKIB1. Moreover, ANKIB1 showed E3 ligase activity both in vivo and in vitro, but it promoted protein ubiquitination more efficiently in vivo. These data suggest that ANKIB1 acts as a partner of an E3 ligase complex, and may play important roles in regulating tumorigenesis and brain cortex function.

scholarly journals The p73 Tumor Suppressor Is Targeted by Pirh2 RING Finger E3 Ubiquitin Ligase for the Proteasome-dependent Degradation

2011 ◽  
Vol 286 (41) ◽  
pp. 35388-35395 ◽  
Author(s):  
Yong-Sam Jung ◽  
Yingjuan Qian ◽  
Xinbin Chen
Keyword(s):  
Tumor Suppressor ◽  
Ubiquitin Ligase ◽  
Human Cancer ◽  
Ectopic Expression ◽  
E3 Ubiquitin Ligase ◽  
Ring Finger ◽  
Growth Suppression ◽  
Dependent Manner

The p73 gene, a homologue of the p53 tumor suppressor, is expressed as TA and ΔN isoforms. TAp73 has similar activity as p53 and functions as a tumor suppressor whereas ΔNp73 has both pro- and anti-survival functions. While p73 is rarely mutated in spontaneous tumors, the expression status of p73 is linked to the sensitivity of tumor cells to chemotherapy and prognosis for many types of human cancer. Thus, uncovering its regulators in tumors is of great interest. Here, we found that Pirh2, a RING finger E3 ubiquitin ligase, promotes the proteasome-dependent degradation of p73. Specifically, we showed that knockdown of Pirh2 up-regulates, whereas ectopic expression of Pirh2 down-regulates, expression of endogenous and exogenous p73. In addition, Pirh2 physically associates with and promotes TAp73 polyubiquitination both in vivo and in vitro. Moreover, we found that p73 can be degraded by both 20 S and 26 S proteasomes. Finally, we showed that Pirh2 knockdown leads to growth suppression in a TAp73-dependent manner. Taken together, our findings indicate that Pirh2 promotes the proteasomal turnover of TAp73, and thus targeting Pirh2 to restore TAp73-mediated growth suppression in p53-deficient tumors may be developed as a novel anti-cancer strategy.

scholarly journals E3 Ubiquitin Ligase SPL2 Is a Lanthanide-Binding Protein

2021 ◽  
Vol 22 (11) ◽  
pp. 5712
Author(s):  
Michał Tracz ◽  
Ireneusz Górniak ◽  
Andrzej Szczepaniak ◽  
Wojciech Białek
Keyword(s):  
Ubiquitin Ligase ◽  
Conformational Changes ◽  
Protein Interactions ◽  
E3 Ubiquitin Ligase ◽  
Lanthanide Ions ◽  
E3 Ligases ◽  
Fluorescence Measurements ◽  
Partial Unfolding

The SPL2 protein is an E3 ubiquitin ligase of unknown function. It is one of only three types of E3 ligases found in the outer membrane of plant chloroplasts. In this study, we show that the cytosolic fragment of SPL2 binds lanthanide ions, as evidenced by fluorescence measurements and circular dichroism spectroscopy. We also report that SPL2 undergoes conformational changes upon binding of both Ca2+ and La3+, as evidenced by its partial unfolding. However, these structural rearrangements do not interfere with SPL2 enzymatic activity, as the protein retains its ability to auto-ubiquitinate in vitro. The possible applications of lanthanide-based probes to identify protein interactions in vivo are also discussed. Taken together, the results of this study reveal that the SPL2 protein contains a lanthanide-binding site, showing for the first time that at least some E3 ubiquitin ligases are also capable of binding lanthanide ions.

CBL mutations drive PI3K/AKT signaling via increased interaction with LYN and PIK3R1

Blood ◽  
2021 ◽  
Author(s):  
Roger Belizaire ◽  
Sebastian Hassan John Koochaki ◽  
Namrata D. Udeshi ◽  
Alexis Vedder ◽  
Lei Sun ◽  
...  
Keyword(s):  
Cell Lines ◽  
Ubiquitin Ligase ◽  
Therapeutic Potential ◽  
Mutant Cell ◽  
E3 Ubiquitin Ligase ◽  
Akt Signaling ◽  
Allelic Series ◽  
Genetic Ablation

CBL encodes an E3 ubiquitin ligase and signaling adaptor that regulates receptor and non-receptor tyrosine kinases. Recurrent CBL mutations occur in myeloid neoplasms, including 10-20% of chronic myelomonocytic leukemia (CMML) cases, and selectively disrupt the protein's E3 ubiquitin ligase activity. CBL mutations have been associated with poor prognosis, but the oncogenic mechanisms and therapeutic implications of CBL mutations remain incompletely understood. We combined functional assays and global mass spectrometry to define the phosphoproteome, CBL interactome, and mechanism of signaling activation in a panel of cell lines expressing an allelic series of CBL mutations. Our analyses revealed that increased LYN activation and interaction with mutant CBL are key drivers of enhanced CBL phosphorylation, PIK3R1 recruitment, and downstream PI3K/AKT signaling in CBL-mutant cells. Signaling adaptor domains of CBL, including the tyrosine-kinase binding domain, proline-rich region, and C-terminal phosphotyrosine sites, were all required for the oncogenic function of CBL mutants. Genetic ablation or dasatinib-mediated inhibition of LYN reduced CBL phosphorylation, CBL-PIK3R1 interaction, and PI3K/AKT signaling. Furthermore, we demonstrated in vitro and in vivo antiproliferative efficacy of dasatinib in CBL-mutant cell lines and primary CMML. Overall, these mechanistic insights into the molecular function of CBL mutations provide rationale to explore the therapeutic potential of LYN inhibition in CBL-mutant myeloid malignancies.

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 Hakin-1, a New Specific Small-Molecule Inhibitor for the E3 Ubiquitin-Ligase Hakai, Inhibits Carcinoma Growth and Progression

Cancers ◽  
2020 ◽  
Vol 12 (5) ◽  
pp. 1340 ◽  
Author(s):  
Olaia Martinez-Iglesias ◽  
Alba Casas-Pais ◽  
Raquel Castosa ◽  
Andrea Díaz-Díaz ◽  
Daniel Roca-Lema ◽  
...  
Keyword(s):  
Small Molecule ◽  
Ubiquitin Ligase ◽  
Epithelial To Mesenchymal Transition ◽  
Tumour Progression ◽  
E3 Ubiquitin Ligase ◽  
Therapeutic Drug ◽  
Mesenchymal Transition ◽  
E Cadherin

The requirement of the E3 ubiquitin-ligase Hakai for the ubiquitination and subsequent degradation of E-cadherin has been associated with enhanced epithelial-to-mesenchymal transition (EMT), tumour progression and carcinoma metastasis. To date, most of the reported EMT-related inhibitors were not developed for anti-EMT purposes, but indirectly affect EMT. On the other hand, E3 ubiquitin-ligase enzymes have recently emerged as promising therapeutic targets, as their specific inhibition would prevent wider side effects. Given this background, a virtual screening was performed to identify novel specific inhibitors of Hakai, targeted against its phosphotyrosine-binding pocket, where phosphorylated-E-cadherin specifically binds. We selected a candidate inhibitor, Hakin-1, which showed an important effect on Hakai-induced ubiquitination. Hakin-1 also inhibited carcinoma growth and tumour progression both in vitro, in colorectal cancer cell lines, and in vivo, in a tumour xenograft mouse model, without apparent systemic toxicity in mice. Our results show for the first time that a small molecule putatively targeting the E3 ubiquitin-ligase Hakai inhibits Hakai-dependent ubiquitination of E-cadherin, having an impact on the EMT process. This represents an important step forward in a future development of an effective therapeutic drug to prevent or inhibit carcinoma tumour progression.

scholarly journals Neuroinflammation-Induced Upregulation of Glial Cathepsin X Expression and Activity in vivo

2020 ◽  
Vol 13 ◽  
Author(s):  
Anja Pišlar ◽  
Larisa Tratnjek ◽  
Gordana Glavan ◽  
Nace Zidar ◽  
Marko Živin ◽  
...  
Keyword(s):  
Neurodegenerative Diseases ◽  
Cellular Localization ◽  
Expression Patterns ◽  
Regional Distribution ◽  
Protective Effects ◽  
Continuous Administration ◽  
Cathepsin X ◽  
Striatal Lesion

Neuroinflammation is an important factor in the pathogenesis of neurodegenerative diseases. Microglia-derived lysosomal cathepsins have been increasingly recognized as important inflammatory mediators that trigger signaling pathways that aggravate neuroinflammation. In vitro, a contribution to neuroinflammation processes has been shown for cathepsin X: however, the expression patterns and functional role of cathepsin X in neuroinflammatory brain pathology remain elusive. In this study we analyzed the expression, activity, regional distribution and cellular localization of cathepsin X in the rat brain with neuroinflammation-induced neurodegeneration. The unilateral injection of lipopolysaccharide (LPS) induced a strong upregulation of cathepsin X expression and its activity in the ipsilateral striatum. In addition to the striatum, cathepsin X overexpression was detected in other brain areas such as the cerebral cortex, corpus callosum, subventricular zone and external globus pallidus, whereas the upregulation was mainly restricted to activated microglia and reactive astrocytes. Continuous administration of the cathepsin X inhibitor AMS36 indicated protective effects against LPS-induced striatal degeneration, as seen by the attenuated LPS-mediated dilation of the lateral ventricles and partial decreased extent of striatal lesion. Taken together, our results indicate that cathepsin X plays a role as a pathogenic factor in neuroinflammation-induced neurodegeneration and represents a potential therapeutic target for neurodegenerative diseases associated with neuroinflammation.

scholarly journals Fat-regulated adaptor protein Dlish binds the growth suppressor Expanded and controls its stability and ubiquitination

2019 ◽  
Vol 116 (4) ◽  
pp. 1319-1324 ◽  
Author(s):  
Xing Wang ◽  
Yifei Zhang ◽  
Seth S. Blair
Keyword(s):  
Ubiquitin Ligase ◽  
Hippo Pathway ◽  
E3 Ubiquitin Ligase ◽  
Growth Control ◽  
Adaptor Protein ◽  
Domain Growth ◽  
C Terminus ◽  
The Hippo Pathway

The Drosophila protocadherin Fat controls organ size through the Hippo pathway, but the biochemical links to the Hippo pathway components are still poorly defined. We previously identified Dlish, an SH3 domain protein that physically interacts with Fat and the type XX myosin Dachs, and showed that Fat’s regulation of Dlish levels and activity helps limit Dachs-mediated inhibition of Hippo pathway activity. We here characterize a parallel growth control pathway downstream of Fat and Dlish. Using immunoprecipitation and mass spectrometry to search for Dlish partners, we find that Dlish binds the FERM domain growth repressor Expanded (Ex); Dlish SH3 domains directly bind sites in the Ex C terminus. We further show that, in vivo, Dlish reduces the subapical accumulation of Ex, and that loss of Dlish blocks the destabilization of Ex caused by loss of Fat. Moreover, Dlish can bind the F-box E3 ubiquitin ligase Slimb and promote Slimb-mediated ubiquitination of Expanded in vitro. Both the in vitro and in vivo effects of Dlish on Ex require Slimb, strongly suggesting that Dlish destabilizes Ex by helping recruit Slimb-containing E3 ubiquitin ligase complexes to Ex.

scholarly journals In Vitro Enhanced Sensitivity to Cisplatin in D67Y BRCA1 RING Domain Protein

2011 ◽  
Vol 5 ◽  
pp. BCBCR.S8184 ◽  
Author(s):  
Apichart Atipairin ◽  
Adisorn Ratanaphan
Keyword(s):  
Dna Damage ◽  
Ubiquitin Ligase ◽  
Dna Damage Repair ◽  
E3 Ubiquitin Ligase ◽  
Chemotherapeutic Agents ◽  
Ring Domain ◽  
Protein Ubiquitination ◽  
Damage Repair ◽  
Domain Protein

BRCA1 is a tumor suppressor protein involved in maintaining genomic integrity through multiple functions in DNA damage repair, transcriptional regulation, cell cycle checkpoint, and protein ubiquitination. The BRCA1-BARD1 RING complex has an E3 ubiquitin ligase function that plays essential roles in response to DNA damage repair. BRCA1-associated cancers have been shown to confer a hypersensitivity to chemotherapeutic agents. Here, we have studied the functional consequence of the in vitro E3 ubiquitin ligase activity and cisplatin sensitivity of the missense mutation D67Y BRCA1 RING domain. The D67Y BRCA1 RING domain protein exhibited the reduced ubiquitination function, and was more susceptible to the drug than the D67E or wild-type BRCA1 RING domain protein. This evidence emphasized the potential of using the BRCA1 dysfunction as an important determinant of chemotherapy responses in breast cancer.

scholarly journals JAC1 suppresses proliferation of breast cancer through the JWA/p38/SMURF1/HER2 signaling

2021 ◽  
Vol 7 (1) ◽  
Author(s):  
Yanlin Ren ◽  
Dongyin Chen ◽  
Zurong Zhai ◽  
Junjie Chen ◽  
Aiping Li ◽  
...  
Keyword(s):  
Breast Cancer ◽  
Cancer Cells ◽  
Ubiquitin Ligase ◽  
Breast Cancer Cells ◽  
E3 Ubiquitin Ligase ◽  
Her2 Positive ◽  
Her2 Positive Breast Cancer ◽  
Positive Breast Cancer

AbstractThe overexpression of HER2 is associated with a malignant proliferation of breast cancer. In this study, we developed a non-cytotoxic JWA gene activating compound 1 (JAC1) to inhibit the proliferation of HER2-positive breast cancer cells in vitro and in vivo experimental models. JAC1 increased the ubiquitination of HER2 at the K716 site through the E3 ubiquitin ligase SMURF1 which was due to the decreased expression of NEDD4, the E3 ubiquitin ligase of SMURF1. In conclusion, JAC1 suppresses the proliferation of HER2-positive breast cancer cells through the JWA triggered HER2 ubiquitination signaling. JAC1 may serve as a potential therapeutic agent for HER2-positive breast cancer.

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