scholarly journals Ehrlichia chaffeensis TRP120 Is a Wnt Ligand Mimetic That Interacts with Wnt Receptors and Contains a Novel Repetitive Short Linear Motif That Activates Wnt Signaling

mSphere ◽  
2021 ◽  
Vol 6 (2) ◽  
Author(s):  
Madison R. Rogan ◽  
LaNisha L. Patterson ◽  
Caitlan D. Byerly ◽  
Tian Luo ◽  
Slobodan Paessler ◽  
...  
Keyword(s):  
Wnt Signaling ◽  
Wnt Pathway ◽  
Immune Cell ◽  
Direct Interaction ◽  
Enzyme Linked Immunosorbent Assay ◽  
Ehrlichia Chaffeensis ◽  
Linear Motif ◽  
Pathway Activity ◽  
Content Type ◽  
Canonical Wnt

ABSTRACT Ehrlichia chaffeensis expresses the TRP120 multifunctional effector, which is known to play a role in phagocytic entry, on the surface of infectious dense-cored ehrlichiae, but a cognate host receptor has not been identified. We recently reported that E. chaffeensis activates canonical Wnt signaling in monocytes to promote bacterial uptake and intracellular survival and that TRP120 was involved in this activation event. To identify the specific mechanism of pathway activation, we hypothesized that TRP120 is a Wnt signaling ligand mimetic that initiates Wnt pathway activity through direct interaction with the Wnt pathway Frizzled family of receptors. In this study, we used confocal immunofluorescence microscopy to demonstrate very strong colocalization between E. chaffeensis and Fzd2, 4, 5, 7, and 9 as well as coreceptor LRP5 at 1 to 3 h postinfection. Direct binding between TRP120 and multiple Fzd receptors was further confirmed by enzyme-linked immunosorbent assay (ELISA) and surface plasmon resonance (SPR). Interfering RNA knockdown of Wnt receptors, coreceptors, and signaling pathway components significantly reduced E. chaffeensis infection, demonstrating that complex and redundant interactions are involved in Wnt pathway exploitation. We utilized in silico approaches to identify a repetitive short linear motif (SLiM) in TRP120 that is homologous to Wnt ligands and used mutant SLiM peptides and an α-TRP120-Wnt-SLiM antibody to demonstrate that the TRP120 Wnt SLiM activates the canonical Wnt pathway and promotes E. chaffeensis infection. This study reports the first example of bacterial mimicry of Wnt pathway ligands and highlights a pathogenic mechanism with potential for targeting by antimicrobial therapeutics. IMPORTANCE Upon infecting mammalian hosts, Ehrlichia chaffeensis establishes a replicative niche in microbe-eating immune system cells where it expertly orchestrates infection and spread. One of the ways Ehrlichia survives within these phagocytes is by activating evolutionarily conserved signaling pathways including the Wnt pathway; however, the molecular details of pathway hijacking have not been defined. This study is significant because it identifies an ehrlichial protein that directly interacts with components of the Wnt receptor complex, influencing pathway activity and promoting infection. Consequentially, Ehrlichia serves as a unique tool to investigate the intricacies of how pathogens repurpose human immune cell signaling and provides an opportunity to better understand many cellular processes in health and disease. Furthermore, understanding how this bacterium utilizes its small genome to survive within cells that evolved to destroy pathogens will facilitate the development of antibacterial therapeutics that could target Ehrlichia as well as other intracellular agents of human disease.

scholarly journals Ehrlichia chaffeensis Exploits Canonical and Noncanonical Host Wnt Signaling Pathways To Stimulate Phagocytosis and Promote Intracellular Survival

2015 ◽  
Vol 84 (3) ◽  
pp. 686-700 ◽  
Author(s):  
Tian Luo ◽  
Paige S. Dunphy ◽  
Taslima T. Lina ◽  
Jere W. McBride
Keyword(s):  
Wnt Signaling ◽  
Host Cell ◽  
Signaling Pathways ◽  
Wnt Pathway ◽  
Target Genes ◽  
Nuclear Translocation ◽  
Intracellular Survival ◽  
Ehrlichia Chaffeensis ◽  
Content Type ◽  
Wnt Pathways

Ehrlichia chaffeensisinvades and survives in phagocytes by modulating host cell processes and evading innate defenses, but the mechanisms are not fully defined. Recently we have determined thatE. chaffeensistandem repeat proteins (TRPs) are type 1 secreted effectors involved in functionally diverse interactions with host targets, including components of the evolutionarily conserved Wnt signaling pathways. In this study, we demonstrated that induction of host canonical and noncanonical Wnt pathways byE. chaffeensisTRP effectors stimulates phagocytosis and promotes intracellular survival. AfterE. chaffeensisinfection, canonical and noncanonical Wnt signalings were significantly stimulated during early stages of infection (1 to 3 h) which coincided with dephosphorylation and nuclear translocation of β-catenin, a major canonical Wnt signal transducer, and NFATC1, a noncanonical Wnt transcription factor. In total, the expression of ∼44% of Wnt signaling target genes was altered during infection. Knockdown of TRP120-interacting Wnt pathway components/regulators and other critical components, such as Wnt5a ligand, Frizzled 5 receptor, β-catenin, nuclear factor of activated T cells (NFAT), and major signaling molecules, resulted in significant reductions in the ehrlichial load. Moreover, small-molecule inhibitors specific for components of canonical and noncanonical (Ca2+and planar cell polarity [PCP]) Wnt pathways, including IWP-2, which blocks Wnt secretion, significantly decreased ehrlichial infection. TRPs directly activated Wnt signaling, as TRP-coated microspheres triggered phagocytosis which was blocked by Wnt pathway inhibitors, demonstrating a key role of TRP activation of Wnt pathways to induce ehrlichial phagocytosis. These novel findings reveal thatE. chaffeensisexploits canonical and noncanonical Wnt pathways through TRP effectors to facilitate host cell entry and promote intracellular survival.

scholarly journals Canonical Wnt Signaling in CD11c+ APCs Regulates Microbiota-Induced Inflammation and Immune Cell Homeostasis in the Colon

2018 ◽  
Vol 200 (9) ◽  
pp. 3259-3268 ◽  
Author(s):  
Daniel Swafford ◽  
Arulkumaran Shanmugam ◽  
Punithavathi Ranganathan ◽  
Mohamed S. Hussein ◽  
Pandelakis A. Koni ◽  
...  
Keyword(s):  
Wnt Signaling ◽  
Immune Cell ◽  
Canonical Wnt Signaling ◽  
Cell Homeostasis ◽  
Canonical Wnt

Noncanonical Wnt5a Is Induced by HTLV-1 bZIP Factor, and Supports Proliferation and Migration of Adult T-Cell Leukemia Cell.

Blood ◽  
2012 ◽  
Vol 120 (21) ◽  
pp. 2405-2405
Author(s):  
Jun-ichirou Yasunaga ◽  
Guangyong Ma ◽  
Jun Fan ◽  
Masao Matsuoka
Keyword(s):  
T Cell ◽  
Wnt Signaling ◽  
Wnt Pathway ◽  
T Cell Leukemia ◽  
Cell Leukemia ◽  
Adult T Cell Leukemia ◽  
Canonical Wnt Pathway ◽  
Bzip Factor ◽  
And Migration ◽  
Canonical Wnt

Abstract Abstract 2405 Adult T-cell leukemia (ATL) is a fatal malignancy of CD4-positive T-cells caused by human T-cell leukemia virus type1 (HTLV-1). HTLV-1 bZIP factor (HBZ) is encoded in the minus strand of HTLV-1 provirus, and is consistently expressed in HTLV-1-infected cells. It has been shown that HBZ promotes proliferation of T-cells, and HBZ-expressing transgenic mice develop T-cell lymphomas and systemic inflammations, suggesting that HBZ has the critical roles in pathogenesis of HTLV-1. However, the molecular mechanisms of HBZ-induced oncogenesis have not been clarified yet. The Wnt signaling is a highly conserved cellular signaling pathway in eukaryotes and the Wnt ligands have been found to trigger multiple pathways of Wnt signaling. The most well-studied cascade is the Wnt/β-catenin pathway (also known as the canonical Wnt pathway), which is β-catenin-dependent and mainly controls cell differentiation, proliferation, and apoptosis. Aberrant activation of the canonical Wnt pathway has been linked to many cancers. In contrast, it is known that the noncanonical Wnt pathway antagonizes the canonical pathway, while a representative noncanonical Wnt ligand, Wnt5a, is suggested to have both oncogenic and tumor suppressive properties in several malignancies. The significance of those Wnt pathways in HTLV-1-associated oncogenesis is still obscure. In this study, we found that HBZ markedly suppressed the canonical Wnt/β-catenin pathway. As a mechanism of HBZ-mediated Wnt suppression, we found that HBZ targets LEF1 and TCF1, the key transcription factors of the pathway, and impairs its DNA-binding ability. In contrast, HTLV-1 Tax protein interacted with Dvl and DAPLE, which are the regulators of the canonical Wnt signaling, and activated the pathway. Indeed, the canonical Wnt activation is not observed in ATL cells, and enforced activation of β-catenin in ATL cells inhibited cellular proliferation, implying that activation of the canonical Wnt pathway might have suppressive effect on ATL cells. On the other hand, HBZ induces the transcription of the noncanonical Wnt5a by enhancing its promoter activity. In addition, Wnt5a transcription level in ATL cells is significantly higher than in HTLV-1-uninifected control cells. Knockdown of Wnt5a impairs both proliferation and migration of ATL cells, suggesting that HBZ-induced Wnt5a supports development and progression of ATL. Our results implicate novel roles of HBZ in ATL leukemogenesis through dysregulation of both the canonical and noncanonical Wnt pathways. Disclosures: No relevant conflicts of interest to declare.

scholarly journals Deubiquitinase USP47/UBP64E Regulates β-Catenin Ubiquitination and Degradation and Plays a Positive Role in Wnt Signaling

2015 ◽  
Vol 35 (19) ◽  
pp. 3301-3311 ◽  
Author(s):  
Jiandang Shi ◽  
Yajuan Liu ◽  
Xuehe Xu ◽  
Wen Zhang ◽  
Tianxin Yu ◽  
...  
Keyword(s):  
Gene Expression ◽  
Rna Interference ◽  
Wnt Signaling ◽  
Wnt Pathway ◽  
Target Gene ◽  
Central Question ◽  
Cancer Cell Growth ◽  
Positive Role ◽  
Content Type

Wnt signaling plays important roles in development and tumorigenesis. A central question about the Wnt pathway is the regulation of β-catenin. Phosphorylation of β-catenin by CK1α and GSK3 promotes β-catenin binding to β-TrCP, leading to β-catenin degradation through the proteasome. The phosphorylation and ubiquitination of β-catenin have been well characterized; however, it is unknown whether and how a deubiquitinase is involved. In this study, by screening RNA interference (RNAi) libraries, we identified USP47 as a deubiquitinase that prevents β-catenin ubiquitination. Inactivation of USP47 by RNAi increased β-catenin ubiquitination, attenuated Wnt signaling, and repressed cancer cell growth. Furthermore, USP47 deubiquitinates itself, whereas β-TrCP promotes USP47 ubiquitination through interaction with an atypical motif in USP47. Finally,in vivostudies in theDrosophilawing suggest that UBP64E, the USP47 counterpart inDrosophila, is required for Armadillo stabilization and plays a positive role in regulating Wnt target gene expression.

scholarly journals A CRISPR knockout screen reveals new regulators of canonical Wnt signaling

Oncogenesis ◽  
2021 ◽  
Vol 10 (9) ◽  
Author(s):  
Tamar Evron ◽  
Michal Caspi ◽  
Michal Kazelnik ◽  
Yarden Shor-Nareznoy ◽  
Shir Armoza-Eilat ◽  
...  
Keyword(s):  
Wnt Signaling ◽  
Wnt Pathway ◽  
Signal Transduction Pathway ◽  
Rapid Identification ◽  
Initiation Factor ◽  
Canonical Wnt Signaling ◽  
New Genes ◽  
A Genome ◽  
Signaling Activation ◽  
Canonical Wnt

AbstractThe Wnt signaling pathways play fundamental roles during both development and adult homeostasis. Aberrant activation of the canonical Wnt signal transduction pathway is involved in many diseases including cancer, and is especially implicated in the development and progression of colorectal cancer. Although extensively studied, new genes, mechanisms and regulatory modulators involved in Wnt signaling activation or silencing are still being discovered. Here we applied a genome-scale CRISPR-Cas9 knockout (KO) screen based on Wnt signaling induced cell survival to reveal new inhibitors of the oncogenic, canonical Wnt pathway. We have identified several potential Wnt signaling inhibitors and have characterized the effects of the initiation factor DExH-box protein 29 (DHX29) on the Wnt cascade. We show that KO of DHX29 activates the Wnt pathway leading to upregulation of the Wnt target gene cyclin-D1, while overexpression of DHX29 inhibits the pathway. Together, our data indicate that DHX29 may function as a new canonical Wnt signaling tumor suppressor and demonstrates that this screening approach can be used as a strategy for rapid identification of novel Wnt signaling modulators.

Abstract 14: The Cytoskeletal Architecture of Myocytes Derived from Human Cardiac Progenitor Cells

2014 ◽  
Vol 115 (suppl_1) ◽  
Author(s):  
Francesco Pasqualini ◽  
Moises Di Sante ◽  
João D Pereira ◽  
Piero Anversa ◽  
Marcello Rota ◽  
...  
Keyword(s):  
Wnt Signaling ◽  
Progenitor Cells ◽  
Wnt Pathway ◽  
Cardiac Cells ◽  
Cardiac Progenitor Cells ◽  
Homogeneous Population ◽  
Cardiomyogenic Differentiation ◽  
Induced Pluripotent ◽  
Canonical Wnt

The stem cell antigen c-kit characterizes a heterogeneous pool of human cardiac progenitor cells (hCPCs) that exhibit a remarkable degree of regenerative potential and are currently employed in clinical trials. While this hCPC pool contains distinct subpopulations of c-kit+ cells that preferentially differentiate into muscular or vascular cardiac cells, we hypothesize that hCPCs may be coerced to specify only along the cardiomyogenic lineage by manipulating the Wnt/β-catenin pathway. We report that pharmacological inhibition of the non-canonical Wnt pathway facilitated the commitment of more than >95% c-kit+ hCPCs to the cardiomyocyte lineage after 4 days in-vitro: this constitutes a substantially more homogeneous population than previously reported with dexamethasone treatment. The hCPC-derived myocytes stained positive for Nkx2.5, a transcription factor that orchestrates cardiomyogenic differentiation, and for the contractile protein sarcomeric α-actin. To test if we could push the cells towards a more mature phenotype, we mimicked the cyclic modulation of the Wnt pathway observed during development. While activation of Wnt signaling resulted in widespread cell death and reduction in cell size, subsequent Wnt inhibition prompted the spared cells to proliferate. With this protocol, hCPC-derived myocytes increased in size and displayed more mature cytoskeletal architectures. In contrast with dexamethasone treated cells, where the localization of α-sarcomeric actinin is mostly diffuse in the cytoplasm, here we observed both Z-bodies and Z-disks like structures. The latter exhibited a periodicity of ~1.6 um and were clustered in larger, more aligned actin bundles. This finding suggests that the tension developed along these cytoskeletal components may play a role in the recruitment of sarcomeric proteins. In conclusion, Wnt signaling inhibition in hCPCs may be sufficient to obtain a homogeneous population of cells with features of myocytes, characterized by improved cytoskeletal organization than dexamethasone treated cells and similar to that observed in myocytes derived from human induced pluripotent stem cells.

scholarly journals R-Spondin Family Members Regulate the Wnt Pathway by a Common Mechanism

2008 ◽  
Vol 19 (6) ◽  
pp. 2588-2596 ◽  
Author(s):  
Kyung-Ah Kim ◽  
Marie Wagle ◽  
Karolyn Tran ◽  
Xiaoming Zhan ◽  
Melissa A. Dixon ◽  
...  
Keyword(s):  
Wnt Signaling ◽  
Wnt Pathway ◽  
Expression Patterns ◽  
Family Members ◽  
Wnt Signaling Pathway ◽  
Direct Consequence ◽  
Common Mechanism ◽  
Wnt Ligands ◽  
Canonical Wnt

The R-Spondin (RSpo) family of secreted proteins is implicated in the activation of the Wnt signaling pathway. Despite the high structural homology between the four members, expression patterns and phenotypes in knockout mice have demonstrated striking differences. Here we dissected and compared the molecular and cellular function of all RSpo family members. Although all four RSpo proteins activate the canonical Wnt pathway, RSpo2 and 3 are more potent than RSpo1, whereas RSpo4 is relatively inactive. All RSpo members require Wnt ligands and LRP6 for activity and amplify signaling of Wnt3A, Wnt1, and Wnt7A, suggesting that RSpo proteins are general regulators of canonical Wnt signaling. Like RSpo1, RSpo2-4 antagonize DKK1 activity by interfering with DKK1 mediated LRP6 and Kremen association. Analysis of RSpo deletion mutants indicates that the cysteine-rich furin domains are sufficient and essential for the amplification of Wnt signaling and inhibition of DKK1, suggesting that Wnt amplification by RSpo proteins may be a direct consequence of DKK1 inhibition. Together, these findings indicate that RSpo proteins modulate the Wnt pathway by a common mechanism and suggest that coexpression with specific Wnt ligands and DKK1 may determine their biological specificity in vivo.

scholarly journals Analysis of Endogenous LRP6 Function Reveals a Novel Feedback Mechanism by Which Wnt Negatively Regulates Its Receptor

2007 ◽  
Vol 27 (20) ◽  
pp. 7291-7301 ◽  
Author(s):  
Zahid Khan ◽  
Sapna Vijayakumar ◽  
Teresa Villanueva de la Torre ◽  
Sabrina Rotolo ◽  
Anna Bafico
Keyword(s):  
Wnt Signaling ◽  
Wnt Pathway ◽  
Mrna Level ◽  
Cellular Membrane ◽  
Feedback Mechanism ◽  
Bone Diseases ◽  
Dependent Manner ◽  
Direct Role ◽  
Initial Stimulus ◽  
Canonical Wnt

ABSTRACT The canonical Wnt pathway plays a crucial role in embryonic development, and its deregulation is involved in human diseases. The LRP6 single-span transmembrane coreceptor is essential for transmission of canonical Wnt signaling. However, due to the lack of immunological reagents, our understanding of LRP6 structure and function has relied on studies involving its overexpression, and regulation of the endogenous receptor by the Wnt ligand has remained unexplored. Using a highly sensitive and specific antibody to LRP6, we demonstrate that the endogenous receptor is modified by N-glycosylation and is phosphorylated in response to Wnt stimulation in a sustained yet ligand-dependent manner. Moreover, following triggering by Wnt, endogenous LRP6 is internalized and recycled back to the cellular membrane within hours of the initial stimulus. Finally, we have identified a novel feedback mechanism by which Wnt, acting through β-catenin, negatively regulates LRP6 at the mRNA level. Together, these findings contribute significantly to our understanding of LRP6 function and uncover a new level of regulation of Wnt signaling. In light of the direct role that the Wnt pathway plays in human bone diseases and malignancies, our findings may support the development of novel therapeutic approaches that target Wnt signaling through LRP6.

scholarly journals Wnt Signaling in Periodontal Disease

2021 ◽  
Vol 2 ◽  
Author(s):  
David González-Quintanilla ◽  
Nicolás Abásolo ◽  
Pablo Astudillo
Keyword(s):  
Periodontal Disease ◽  
Wnt Signaling ◽  
Periodontal Ligament ◽  
Chronic Condition ◽  
Wnt Pathway ◽  
Alveolar Bone ◽  
Canonical Pathways ◽  
Canonical Wnt ◽  
Proper Balance

Periodontitis is a multifactorial and chronic condition associated with the formation of a dysbiotic biofilm, leading to a pro-inflammatory environment that can modulate cell signaling. The Wnt pathway plays fundamental roles during homeostasis and disease, and emerging evidence suggests its involvement in the maintenance of the periodontium and the development of periodontitis. Here, we summarize the role of the Wnt/β-catenin and non-canonical Wnt signaling pathways in periodontitis. The accumulated data suggests specific roles for each branch of the Wnt pathway. Wnt5a emerges as a critical player promoting periodontal ligament remodeling and impairing regenerative responses modulated by the Wnt/β-catenin pathway, such as alveolar bone formation. Collectively, the evidence suggests that achieving a proper balance between the Wnt/β-catenin and non-canonical pathways, rather than their independent modulation, might contribute to controlling the progression and severity of the periodontal disease.

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