scholarly journals A screen for targets of the Drosophila pseudokinase Tribbles identifies Neuralized and Mindbomb, ubiquitin ligases that mediate Notch signaling

2018 ◽  
Author(s):  
Anna Shipman ◽  
Christopher Nauman ◽  
Britney Haymans ◽  
Rachel Silverstein ◽  
Leonard L. Dobens
Keyword(s):  
Cell Differentiation ◽  
Family Members ◽  
Notch Pathway ◽  
Ubiquitin Ligases ◽  
Adaptor Proteins ◽  
Tissue Growth ◽  
E3 Ligases ◽  
Tissue Size ◽  
Factor C ◽  
Notch Activation

ABSTRACTDrosophila Tribbles (Trbl) is the founding member of a family of pseudokinases with conserved roles in antagonizing cell division, tissue growth and cell differentiation. In humans, three Tribbles isoforms serve as adaptor proteins, binding targets such as Cdc25 phosphatase, Akt kinase or the transcription factor C/EBP to block their activity or direct their proteosomal degradation. Mutations in Tribbles family members are associated with susceptibility to diabetes and cancer, notably Notch-induced tumor growth. Trbl misexpression in the fly wing disk leads to a block in mitosis associated with decreased levels of String/Cdc25 and increased levels of Cyclin B leading to reduced overall wing size and reduced trichome density. We show these Trbl growth-restricting phenotypes can be suppressed by manipulating levels of known Trbl targets, and use this sensitized wing system to screen a collection of growth regulating open reading frames (ORFs) to search for enhancers and suppressors affecting cell and tissue size. By precisely measuring morphometric changes in wing phenotypes using a computer-based tool, we detected synthetic interactions with several E3 ubiquitin ligases, and focused our analysis on the Notch pathway components Neuralized (Neur) and Mindbomb1 (Mib1). In the wing, notum and egg chamber epithelia, Trbl misexpression suppressed Neur and Mib1 activities and stabilized the accumulation of both proteins. To understand these interactions, we used yeast two-hybrid assays to show Trbl physically bound to both Neur and Mib1. Our data are consistent with published reports that mammalian Tribbles3 modulates Notch responses by binding and stabilizing Mindbomb and indicate that a wing misexpression approach is useful to identify novel components in a conserved Tribbles signaling pathway.AUTHOR SUMMARYTribbles pseudokinases are adaptor molecules, binding diverse targets regulating cell differentiation, growth and proliferation and directing their proteasomal degradation. To search for novel targets of Drosophila Tribbles, we adopted a wing co-misexpression scheme and measured changes in cell/tissue size to identify enhancers and suppressors of the Tribbles phenotype. We show the Notch pathway components Neuralized and Mindbomb1 E3 ligases act as Tribbles suppressors and demonstrate that Tribbles modulates their levels and activites. Recent demonstration that mammalian Tribbles 3 binds the E3 ligase Mindbomb to promote ligand-mediated Notch activation implies a conserved role for Tribbles family members in Notch activation.

Trib1 and Trib2 but Not Trib3 Degrade C/EBPá and Induce Acute Myelogenous Leukemia

Blood ◽  
2008 ◽  
Vol 112 (11) ◽  
pp. 2950-2950
Author(s):  
Priya Dedhia ◽  
Karen Keeshan ◽  
Maria Vega ◽  
Sacha Uljon ◽  
Lanwei Xu ◽  
...  
Keyword(s):  
Transcription Factor ◽  
Mrna Expression ◽  
Acute Myelogenous Leukemia ◽  
Family Members ◽  
Myelogenous Leukemia ◽  
Hematopoietic Progenitors ◽  
E3 Ligases ◽  
Evolutionarily Conserved ◽  
Acute Myelogenous ◽  
Factor C

Abstract Trib1, Trib2, and Trib3 are mammalian homologues of the Tribbles protein family, an evolutionarily conserved group of proteins that can mediate proteasome-dependent degradation. Evidence suggests that these proteins function as adapters, where they recruit E3 ligases and enhance ubiquination of the target protein in order to promote its degradation. To date, increased Trib1 and Trib2 mRNA expression has been shown to correlate with acute myelogenous leukemia (AML) in humans and induces AML in mice; whereas Trib3 has not been associated with AML. In order to understand the effects of Trib family members in hematopoietic cells, we reconstituted mice with hematopoietic progenitors retrovirally expressing Trib1, Trib2, or Trib3. Trib1 and Trib2 mice developed AML whereas Trib3 mice did not. Our previous data suggested that Trib2-mediated degradation of the transcription factor, C/EBPα, is important for leukemogenesis. We now show that Trib1, like Trib2, strongly binds C/EBPα and induces its degradation. In contrast, Trib3 weakly binds C/EBPα and fails to induce its degradation. Consistent with the ability to strongly bind and degrade C/EBPα, Trib1 and Trib2, but not Trib3, block differentiation of myeloid cells. We are currently mapping the domains that account for the differences between Trib1/Trib2 and Trib3 in leukemogenesis. Together, our results strengthen the correlation between Trib-induced C/EBPα degradation and induction of AML. Furthermore, our data show that different Tribbles family members have distinct targets and understanding this specificity may provide opportunities to therapeutically target Tribbles.

scholarly journals 3375 Chronic inflammation promotes intestinal macrophages to become modulators of the Notch pathway

2019 ◽  
Vol 3 (s1) ◽  
pp. 4-5
Author(s):  
Eliseo Castillo
Keyword(s):  
T Cells ◽  
Cell Differentiation ◽  
Chronic Inflammation ◽  
Bacterial Translocation ◽  
Intestinal Inflammation ◽  
Notch Pathway ◽  
Goblet Cells ◽  
Chronic Colitis ◽  
Notch Ligand ◽  
Notch Activation

OBJECTIVES/SPECIFIC AIMS: The purpose of this research was to investigate how chronic inflammation promotes the generation of proinflammatory intestinal macrophages and if macrophages contribute to intestinal inflammation through Notch activation. METHODS/STUDY POPULATION: We utilized two animal models of chronic colitis, the chronic DSS-induced colitis mouse model and the spontaneous enterocolitis development in IL-10-deficient mice to investigate the role of chronic inflammation in the generation of proinflammatory intestinal macrophages and its influence in notch signaling. Bone marrow-derived monocytes were collected from each group and differentiated into macrophages (BMM) for gene and protein analysis. Ex vivo phenotypical and functional analysis of colonic macrophages was assessed as was the presence of goblet cells and mucosal T cells. In addition, we analyzed the development of goblet cell differentiation in colonoids in a co-culture system with proinflammatory macrophages. RESULTS/ANTICIPATED RESULTS: Our chronic inflammation models revealed an increase in proinflammatory macrophages present in the lamina propria and that these cells expressed significantly higher levels of notch ligand, Jagged1. Jagged 1 has been shown to enhance TH1 differentiation and T cells isolated from the mucosa of both chronic colitis models display strong TH1 skewing compared to controls. Chronic inflammation also contributes to intestinal barrier defects, enhanced permeability and bacterial translocation. We believe this enhanced intestinal permeability and subsequent bacterial translocation promote Jagged1 expression in intestinal macrophages. To support this concept, we show TLR stimulation induces the upregulation of Jagged1 in BMM. Additionally, the generation of BMM from our chronic DSS-induced colitis mice or age matched controls, revealed BMM derived from a host of chronic inflammation were skewed to a proinflammatory state prior to stimulation showing increased gene expression of several proinflammatory molecules including IL-1α, IL-1β, IL-12 and TNF-α. This would suggest monocytes migrating to the intestinal mucosa have more potential to become proinflammatory instead of traditional anti-inflammatory macrophages. Furthermore, proinflammatory notch ligand-positive macrophages co-cultured with colonoids, derived from unperturbed mice, significantly decreased the number of mucus producing goblet cells. In support of this observation, notch activation in intestinal stem cells promote absorptive (i.e. colonocytes) cell differentiation and prevents secretory cell (i.e. goblet cells) differentiation. DISCUSSION/SIGNIFICANCE OF IMPACT: Taken together, our results strongly suggest chronic inflammation modulates macrophages role in maintaining intestinal homeostasis through possible notch activation in both T cells and the intestinal epithelial barrier.

scholarly journals Natural Herbal Estrogen-Mimetics (Phytoestrogens) Promote the Differentiation of Fallopian Tube Epithelium into Multi-Ciliated Cells via Estrogen Receptor Beta

Molecules ◽  
2021 ◽  
Vol 26 (3) ◽  
pp. 722
Author(s):  
Maobi Zhu ◽  
Sen Takeda ◽  
Tomohiko Iwano
Keyword(s):  
Estrogen Receptor ◽  
Cell Differentiation ◽  
Epithelial Cells ◽  
Fallopian Tube ◽  
Ciliated Cell ◽  
Estrogen Receptor Beta ◽  
Notch Pathway ◽  
Secretory Cells ◽  
Ciliated Cells ◽  
Receptor Beta

Phytoestrogens are herbal polyphenolic compounds that exert various estrogen-like effects in animals and can be taken in easily from a foodstuff in daily life. The fallopian tube lumen, where transportation of the oocyte occurs, is lined with secretory cells and multi-ciliated epithelial cells. Recently, we showed that estrogen induces multi-ciliogenesis in the porcine fallopian tube epithelial cells (FTECs) through the activation of the estrogen receptor beta (ERβ) pathway and simultaneous inhibition of the Notch pathway. Thus, ingested phytoestrogens may induce FTEC ciliogenesis and thereby affect the fecundity. To address this issue, we added isoflavones (genistein, daidzein, or glycitin) and coumestan (coumestrol) to primary culture FTECs under air–liquid interface conditions and assessed the effects of each compound. All phytoestrogens except glycitin induced multi-ciliated cell differentiation, which followed Notch signal downregulation. On the contrary, the differentiation of secretory cells decreased slightly. Furthermore, genistein and daidzein had a slight effect on the proportion of proliferating cells exhibited by Ki67 expression. Ciliated-cell differentiation is inhibited by the ERβ antagonist, PHTPP. Thus, this study suggests that phytoestrogens can improve the fallopian tube epithelial sheet homeostasis by facilitating the genesis of multi-ciliated cells and this effect depends on the ERβ-mediated pathway.

scholarly journals Interplay of BAF and MLL4 promotes cell type-specific enhancer activation

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Young-Kwon Park ◽  
Ji-Eun Lee ◽  
Zhijiang Yan ◽  
Kaitlin McKernan ◽  
Tommy O’Haren ◽  
...  
Keyword(s):  
Cell Differentiation ◽  
Chromatin Remodeling ◽  
Direct Evidence ◽  
Cell Type ◽  
Chromatin Regulators ◽  
Chromatin Remodeling Complex ◽  
Histone H3k4 ◽  
Cell Type Specific ◽  
Pioneer Transcription Factor ◽  
Factor C

AbstractCell type-specific enhancers are activated by coordinated actions of lineage-determining transcription factors (LDTFs) and chromatin regulators. The SWI/SNF chromatin remodeling complex BAF and the histone H3K4 methyltransferase MLL4 (KMT2D) are both implicated in enhancer activation. However, the interplay between BAF and MLL4 in enhancer activation remains unclear. Using adipogenesis as a model system, we identify BAF as the major SWI/SNF complex that colocalizes with MLL4 and LDTFs on active enhancers and is required for cell differentiation. In contrast, the promoter enriched SWI/SNF complex PBAF is dispensable for adipogenesis. By depleting BAF subunits SMARCA4 (BRG1) and SMARCB1 (SNF5) as well as MLL4 in cells, we show that BAF and MLL4 reciprocally regulate each other’s binding on active enhancers before and during adipogenesis. By focusing on enhancer activation by the adipogenic pioneer transcription factor C/EBPβ without inducing cell differentiation, we provide direct evidence for an interdependent relationship between BAF and MLL4 in activating cell type-specific enhancers. Together, these findings reveal a positive feedback between BAF and MLL4 in promoting LDTF-dependent activation of cell type-specific enhancers.

scholarly journals Comprehensive database of human E3 ubiquitin ligases: application to aquaporin-2 regulation

2016 ◽  
Vol 48 (7) ◽  
pp. 502-512 ◽  
Author(s):  
Barbara Medvar ◽  
Viswanathan Raghuram ◽  
Trairak Pisitkun ◽  
Abhijit Sarkar ◽  
Mark A. Knepper
Keyword(s):  
Human Genome ◽  
Large Scale ◽  
E3 Ligase ◽  
Ubiquitin Ligases ◽  
Bayes Rule ◽  
E3 Ubiquitin Ligases ◽  
E3 Ligases ◽  
Aquaporin 2 ◽  
Large Scale Data ◽  
Level Data

Aquaporin-2 (AQP2) is regulated in part via vasopressin-mediated changes in protein half-life that are in turn dependent on AQP2 ubiquitination. Here we addressed the question, “What E3 ubiquitin ligase is most likely to be responsible for AQP2 ubiquitination?” using large-scale data integration based on Bayes' rule. The first step was to bioinformatically identify all E3 ligase genes coded by the human genome. The 377 E3 ubiquitin ligases identified in the human genome, consisting predominant of HECT, RING, and U-box proteins, have been used to create a publically accessible and downloadable online database ( https://hpcwebapps.cit.nih.gov/ESBL/Database/E3-ligases/ ). We also curated a second database of E3 ligase accessory proteins that included BTB domain proteins, cullins, SOCS-box proteins, and F-box proteins. Using Bayes' theorem to integrate information from multiple large-scale proteomic and transcriptomic datasets, we ranked these 377 E3 ligases with respect to their probability of interaction with AQP2. Application of Bayes' rule identified the E3 ligases most likely to interact with AQP2 as (in order of probability): NEDD4 and NEDD4L (tied for first), AMFR, STUB1, ITCH, ZFPL1. Significantly, the two E3 ligases tied for top rank have also been studied extensively in the reductionist literature as regulatory proteins in renal tubule epithelia. The concordance of conclusions from reductionist and systems-level data provides strong motivation for further studies of the roles of NEDD4 and NEDD4L in the regulation of AQP2 protein turnover.

scholarly journals Respiratory Failure Due to Differentiation Arrest and Expansion of Alveolar Cells following Lung-Specific Loss of the Transcription Factor C/EBPα in Mice

2006 ◽  
Vol 26 (3) ◽  
pp. 1109-1123 ◽  
Author(s):  
Daniela S. Bassères ◽  
Elena Levantini ◽  
Hongbin Ji ◽  
Stefano Monti ◽  
Shannon Elf ◽  
...  
Keyword(s):  
Transcription Factor ◽  
Cell Differentiation ◽  
Respiratory Failure ◽  
Leucine Zipper ◽  
Type I ◽  
Type Ii ◽  
Alveolar Cells ◽  
Proliferating Cells ◽  
Therapeutic Benefits ◽  
Factor C

ABSTRACT The leucine zipper family transcription factor CCAAT enhancer binding protein alpha (C/EBPα) inhibits proliferation and promotes differentiation in various cell types. In this study, we show, using a lung-specific conditional mouse model of C/EBPα deletion, that loss of C/EBPα in the respiratory epithelium leads to respiratory failure at birth due to an arrest in the type II alveolar cell differentiation program. This differentiation arrest results in the lack of type I alveolar cells and differentiated surfactant-secreting type II alveolar cells. In addition to showing a block in type II cell differentiation, the neonatal lungs display increased numbers of proliferating cells and decreased numbers of apoptotic cells, leading to epithelial expansion and loss of airspace. Consistent with the phenotype observed, genes associated with alveolar maturation, survival, and proliferation were differentially expressed. Taken together, these results identify C/EBPα as a master regulator of airway epithelial maturation and suggest that the loss of C/EBPα could also be an important event in the multistep process of lung tumorigenesis. Furthermore, this study indicates that exploring the C/EBPα pathway might have therapeutic benefits for patients with respiratory distress syndromes.

scholarly journals Inhibition of HECT E3 ligases as potential therapy for COVID-19

2021 ◽  
Vol 12 (4) ◽  
Author(s):  
Giuseppe Novelli ◽  
◽  
Jing Liu ◽  
Michela Biancolella ◽  
Tonino Alonzi ◽  
...  
Keyword(s):  
World Wide ◽  
Therapeutic Strategy ◽  
Rna Viruses ◽  
Family Members ◽  
E3 Ligase ◽  
Direct Interaction ◽  
Spike Protein ◽  
E3 Ligases ◽  
Antiviral Effects ◽  
Novel Biomarkers

AbstractSARS-CoV-2 is responsible for the ongoing world-wide pandemic which has already taken more than two million lives. Effective treatments are urgently needed. The enzymatic activity of the HECT-E3 ligase family members has been implicated in the cell egression phase of deadly RNA viruses such as Ebola through direct interaction of its VP40 Protein. Here we report that HECT-E3 ligase family members such as NEDD4 and WWP1 interact with and ubiquitylate the SARS-CoV-2 Spike protein. Furthermore, we find that HECT family members are overexpressed in primary samples derived from COVID-19 infected patients and COVID-19 mouse models. Importantly, rare germline activating variants in the NEDD4 and WWP1 genes are associated with severe COVID-19 cases. Critically, I3C, a natural NEDD4 and WWP1 inhibitor from Brassicaceae, displays potent antiviral effects and inhibits viral egression. In conclusion, we identify the HECT family members of E3 ligases as likely novel biomarkers for COVID-19, as well as new potential targets of therapeutic strategy easily testable in clinical trials in view of the established well-tolerated nature of the Brassicaceae natural compounds.

scholarly journals Comprehensive Analysis of E3 Ubiquitin Ligases Reveals Ring Finger Protein 223 as a Novel Oncogene Activated by KLF4 in Pancreatic Cancer

2021 ◽  
Vol 9 ◽  
Author(s):  
Lei Feng ◽  
Jieqing Wang ◽  
Jianmin Zhang ◽  
Jingfang Diao ◽  
Longguang He ◽  
...  
Keyword(s):  
Pancreatic Cancer ◽  
Transcriptional Activation ◽  
Prognostic Significance ◽  
Ring Finger ◽  
Ubiquitin Ligases ◽  
The Cancer Genome Atlas ◽  
Differentially Expressed ◽  
E3 Ubiquitin Ligases ◽  
E3 Ligases ◽  
Elevated Expression

Pancreatic cancer is one of the major malignancies and causes of mortality worldwide. E3 ubiquitin–protein ligases transfer activated ubiquitin from ubiquitin-conjugating enzymes to protein substrates and confer substrate specificity in cancer. In this study, we first downloaded data from The Cancer Genome Atlas pancreatic adenocarcinoma dataset, acquired all 27 differentially expressed genes (DEGs), and identified genomic alterations. Then, the prognostic significance of DEGs was analyzed, and eight DEGs (MECOM, CBLC, MARCHF4, RNF166, TRIM46, LONRF3, RNF39, and RNF223) and two clinical parameters (pathological N stage and T stage) exhibited prognostic significance. RNF223 showed independent significance as an unfavorable prognostic marker and was chosen for subsequent analysis. Next, the function of RNF223 in the pancreatic cancer cell lines ASPC-1 and PANC-1 was investigated, and RNF223 silencing promoted pancreatic cancer growth and migration. To explore the potential targets and pathways of RNF223 in pancreatic cancer, quantitative proteomics was applied to analyze differentially expressed proteins, and metabolism-related pathways were primarily enriched. Finally, the reason for the elevated expression of RNF223 was analyzed, and KLF4 was shown to contribute to the increased expression of RNF233. In conclusion, this study comprehensively analyzed the clinical significance of E3 ligases. Functional assays revealed that RNF223 promotes cancer by regulating cell metabolism. Finally, the elevated expression of RNF223 was attributed to KLF4-mediated transcriptional activation. This study broadens our knowledge regarding E3 ubiquitin ligases and signal transduction and provides novel markers and therapeutic targets in pancreatic cancer.

scholarly journals Drosophila IMP regulates Kuzbanian to control the timing of Notch signalling in the follicle cells

2018 ◽  
Author(s):  
Weronika Fic ◽  
Celia Faria ◽  
Daniel St Johnston
Keyword(s):  
Rna Binding ◽  
Notch Pathway ◽  
Notch Signalling ◽  
Follicle Cells ◽  
Over Expression ◽  
Apical Domain ◽  
Late Endosomes ◽  
Notch Cleavage ◽  
Mirna Pathway ◽  
Notch Activation

AbstractThe timing of Drosophila egg chamber development is controlled by a germline Delta signal that activates Notch in the follicle cells to induce them to cease proliferation and differentiate. Here we report that follicle cells lacking the RNA-binding protein IMP go through one extra division due to a delay in the Delta-dependent S2 cleavage of Notch. The timing of Notch activation has previously been shown to be controlled by cis-inhibition by Delta in the follicle cells, which is relieved when the miRNA pathway represses Delta expression. imp mutants are epistatic to Delta mutants and give an additive phenotype with belle and dicer mutants, indicating that IMP functions independently of both cis-inhibition and the miRNA pathway. We find that the imp phenotype is rescued by over-expression of Kuzbanian, the metalloprotease that mediates the Notch S2 cleavage. Furthermore, Kuzbanian is not enriched at the apical membrane in imp mutants, accumulating instead in late endosomes. Thus, IMP regulates Notch signalling by controlling the localisation of Kuzbanian to the apical domain, where Notch cleavage occurs, revealing a novel regulatory step in the Notch pathway.SummaryIMP regulates Notch signalling in follicle cells by controlling Kuzbanian localisation to the apical domain, where Notch cleavage occurs, revealing a novel regulatory step in the Notch pathway.

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