scholarly journals The microRNA miR-8 is a conserved negative regulator of Wnt signaling

2008 ◽  
Vol 105 (40) ◽  
pp. 15417-15422 ◽  
Author(s):  
Jennifer A. Kennell ◽  
Isabelle Gerin ◽  
Ormond A. MacDougald ◽  
Ken M. Cadigan
Keyword(s):  
Wnt Signaling ◽  
Signaling Pathway ◽  
Target Genes ◽  
Wnt Signaling Pathway ◽  
Negative Regulator ◽  
Animal Development ◽  
Protein Levels ◽  
Evolutionarily Conserved ◽  
Multiple Levels

Wnt signaling plays many important roles in animal development. This evolutionarily conserved signaling pathway is highly regulated at all levels. To identify regulators of the Wnt/Wingless (Wg) pathway, we performed a genetic screen in Drosophila. We identified the microRNA miR-8 as an inhibitor of Wg signaling. Expression of miR-8 potently antagonizes Wg signaling in vivo, in part by directly targeting wntless, a gene required for Wg secretion. In addition, miR-8 inhibits the pathway downstream of the Wg signal by repressing TCF protein levels. Another positive regulator of the pathway, CG32767, is also targeted by miR-8. Our data suggest that miR-8 potently antagonizes the Wg pathway at multiple levels, from secretion of the ligand to transcription of target genes. In addition, mammalian homologues of miR-8 promote adipogenesis of marrow stromal cells by inhibiting Wnt signaling. These findings indicate that miR-8 family members play an evolutionarily conserved role in regulating the Wnt signaling pathway.

scholarly journals Wnt/β-Catenin/Tcf Signaling Induces the Transcription of Axin2, a Negative Regulator of the Signaling Pathway

2002 ◽  
Vol 22 (4) ◽  
pp. 1172-1183 ◽  
Author(s):  
Eek-hoon Jho ◽  
Tong Zhang ◽  
Claire Domon ◽  
Choun-Ki Joo ◽  
Jean-Noel Freund ◽  
...  
Keyword(s):  
Wnt Signaling ◽  
Signaling Pathway ◽  
Wnt Pathway ◽  
Genomic Sequence ◽  
Wnt Signaling Pathway ◽  
Genomic Region ◽  
Negative Regulator ◽  
Mobility Shift ◽  
Specific Expression

ABSTRACT Axin2/Conductin/Axil and its ortholog Axin are negative regulators of the Wnt signaling pathway, which promote the phosphorylation and degradation of β-catenin. While Axin is expressed ubiquitously, Axin2 mRNA was seen in a restricted pattern during mouse embryogenesis and organogenesis. Because many sites of Axin2 expression overlapped with those of several Wnt genes, we tested whether Axin2 was induced by Wnt signaling. Endogenous Axin2 mRNA and protein expression could be rapidly induced by activation of the Wnt pathway, and Axin2 reporter constructs, containing a 5.6-kb DNA fragment including the promoter and first intron, were also induced. This genomic region contains eight Tcf/LEF consensus binding sites, five of which are located within longer, highly conserved noncoding sequences. The mutation or deletion of these Tcf/LEF sites greatly diminished induction by β-catenin, and mutation of the Tcf/LEF site T2 abolished protein binding in an electrophoretic mobility shift assay. These results strongly suggest that Axin2 is a direct target of the Wnt pathway, mediated through Tcf/LEF factors. The 5.6-kb genomic sequence was sufficient to direct the tissue-specific expression of d2EGFP in transgenic embryos, consistent with a role for the Tcf/LEF sites and surrounding conserved sequences in the in vivo expression pattern of Axin2. Our results suggest that Axin2 participates in a negative feedback loop, which could serve to limit the duration or intensity of a Wnt-initiated signal.

Abstract 361: Activation of Wnt Pathway in Macrophages During Atherosclerosis Regression

2015 ◽  
Vol 35 (suppl_1) ◽  
Author(s):  
Prashanthi Menon ◽  
Yulia Vengrenyuk ◽  
Yoscar Ogando ◽  
Stephen Ramsey ◽  
Elizabeth Gold ◽  
...  
Keyword(s):  
Wnt Signaling ◽  
Signaling Pathway ◽  
Mouse Models ◽  
Target Genes ◽  
Wnt Signaling Pathway ◽  
Macrophage Migration ◽  
Canonical Wnt Signaling ◽  
Canonical Wnt

Introduction and Objective: Transcriptome analysis of plaque macrophages in two different mouse models of atherosclerosis regression revealed an over representation of consensus binding site sequences for the T-cell factor (TCF)/Lymphoid enhancer binding factor (LEF) family of transcription factors, suggesting canonical Wnt signaling pathway activation during regression in vivo. The canonical Wnt/β-catenin signaling pathway is important for cardiac development and regulates processes such as migration, invasion and tissue repair. However, its function in plaque macrophages is unclear. The objective of the study was to understand the role of canonical Wnt signaling in macrophages during regression using in vivo and in vitro approaches. Methods and Results: Immunohistochemistry of atherosclerotic arterial sections in mouse models of atherosclerosis regression (Reversa and aortic arch transplant) showed a significant increase in β-catenin expression in regressing vs. progressing macrophages. Elevated transcript levels of canonical Wnt downstream targets Ctnnb1, Lrp1 and Gja1 were detected in regressing plaque macrophages isolated by laser capture microdissection (LCM). Canonical Wnt signaling was further investigated in Wnt3a-stimulated primary bone marrow-derived macrophages (BMDM) in vitro, revealing upregulation of pathway target genes Ctnnb1 and Axin2. Furthermore, immunofluorescence analysis of BMDM stimulated with Wnt3a showed increased nuclear expression of β-catenin. Macrophage cell migration evaluated by scratch wound assay revealed a significant increase in migration in Wnt3a-treated vs. untreated BMDM. Conclusions: Our findings demonstrate that canonical Wnt signaling is activated in regressing plaque macrophages and regulates macrophage migration in vitro. Future studies are aimed at understanding the mechanism by which Wnt modulates macrophage migration.

scholarly journals DNA methylation mediated RSPO2 to promote follicular development in mammals

2021 ◽  
Vol 12 (7) ◽  
Author(s):  
Xiaofeng Zhou ◽  
Yingting He ◽  
Nian Li ◽  
Guofeng Bai ◽  
Xiangchun Pan ◽  
...  
Keyword(s):  
Dna Methylation ◽  
Wnt Signaling ◽  
Signaling Pathway ◽  
Methylation Level ◽  
Molecular Mechanisms ◽  
Cpg Island ◽  
Wnt Signaling Pathway ◽  
Follicular Development ◽  
Expression Level

AbstractIn female mammals, the proliferation, apoptosis, and estradiol-17β (E2) secretion of granulosa cells (GCs) have come to decide the fate of follicles. DNA methylation and RSPO2 gene of Wnt signaling pathway have been reported to involve in the survival of GCs and follicular development. However, the molecular mechanisms for how DNA methylation regulates the expression of RSPO2 and participates in the follicular development are not clear. In this study, we found that the mRNA and protein levels of RSPO2 significantly increased during follicular development, but the DNA methylation level of RSPO2 promoter decreased gradually. Inhibition of DNA methylation or DNMT1 knockdown could decrease the methylation level of CpG island (CGI) in RSPO2 promoter and upregulate the expression level of RSPO2 in porcine GCs. The hypomethylation of −758/−749 and −563/−553 regions in RSPO2 promoter facilitated the occupancy of transcription factor E2F1 and promoted the transcriptional activity of RSPO2. Moreover, RSPO2 promoted the proliferation of GCs with increasing the expression level of PCNA, CDK1, and CCND1 and promoted the E2 secretion of GCs with increasing the expression level of CYP19A1 and HSD17B1 and inhibited the apoptosis of GCs with decreasing the expression level of Caspase3, cleaved Caspase3, cleaved Caspase8, cleaved Caspase9, cleaved PARP, and BAX. In addition, RSPO2 knockdown promoted the apoptosis of GCs, blocked the development of follicles, and delayed the onset of puberty with decreasing the expression level of Wnt signaling pathway-related genes (LGR4 and CTNNB1) in vivo. Taken together, the hypomethylation of −758/−749 and −563/−553 regions in RSPO2 promoter facilitated the occupancy of E2F1 and enhanced the transcription of RSPO2, which further promoted the proliferation and E2 secretion of GCs, inhibited the apoptosis of GCs, and ultimately ameliorated the development of follicles through Wnt signaling pathway. This study will provide useful information for further exploration on DNA-methylation-mediated RSPO2 pathway during follicular development.

scholarly journals Inhibition of Wnt signaling by ICAT, a novel β-catenin-interacting protein

2000 ◽  
Vol 14 (14) ◽  
pp. 1741-1749 ◽  
Author(s):  
Ken-ichi Tago ◽  
Tsutomu Nakamura ◽  
Michiru Nishita ◽  
Junko Hyodo ◽  
Shin-ichi Nagai ◽  
...  
Keyword(s):  
Cell Proliferation ◽  
Transcription Factors ◽  
Embryonic Development ◽  
Wnt Signaling ◽  
Signaling Pathway ◽  
Target Genes ◽  
Wnt Signaling Pathway ◽  
Axis Formation ◽  
Interacting Protein

Wnt signaling has an important role in both embryonic development and tumorigenesis. β-Catenin, a key component of the Wnt signaling pathway, interacts with the TCF/LEF family of transcription factors and activates transcription of Wnt target genes. Here, we identify a novel β-catenin-interacting protein, ICAT, that was found to inhibit the interaction of β-catenin with TCF-4 and represses β-catenin–TCF-4-mediated transactivation. Furthermore, ICAT inhibited Xenopus axis formation by interfering with Wnt signaling. These results suggest that ICAT negatively regulates Wnt signaling via inhibition of the interaction between β-catenin and TCF and is integral in development and cell proliferation.

scholarly journals Dickkopf Wnt signaling pathway inhibitor 1 regulates the differentiation of mouse embryonic stem cells in vitro and in vivo

2015 ◽  
Vol 13 (1) ◽  
pp. 720-730 ◽  
Author(s):  
LIPING OU ◽  
LIAOQIONG FANG ◽  
HEJING TANG ◽  
HAI QIAO ◽  
XIAOMEI ZHANG ◽  
...  
Keyword(s):  
Stem Cells ◽  
Embryonic Stem Cells ◽  
Wnt Signaling ◽  
Signaling Pathway ◽  
Wnt Signaling Pathway ◽  
Embryonic Stem ◽  
Mouse Embryonic Stem Cells

scholarly journals Silencing of long noncoding RNA HOXA11-AS inhibits the Wnt signaling pathway via the upregulation of HOXA11 and thereby inhibits the proliferation, invasion, and self-renewal of hepatocellular carcinoma stem cells

2019 ◽  
Vol 51 (11) ◽  
pp. 1-20 ◽  
Author(s):  
Jun-Cheng Guo ◽  
Yi-Jun Yang ◽  
Jin-Fang Zheng ◽  
Jian-Quan Zhang ◽  
Min Guo ◽  
...  
Keyword(s):  
Hepatocellular Carcinoma ◽  
Stem Cells ◽  
Stem Cell ◽  
Wnt Signaling ◽  
Signaling Pathway ◽  
Methylation Level ◽  
Wnt Signaling Pathway ◽  
The Self ◽  
Self Renewal

AbstractHepatocellular carcinoma (HCC) is a major cause of cancer-related deaths, but its molecular mechanisms are not yet well characterized. Long noncoding RNAs (lncRNAs) play crucial roles in tumorigenesis, including that of HCC. However, the role of homeobox A11 antisense (HOXA11-AS) in determining HCC stem cell characteristics remains to be explained; hence, this study aimed to investigate the effects of HOXA11-AS on HCC stem cell characteristics. Initially, the expression patterns of HOXA11-AS and HOXA11 in HCC tissues, cells, and stem cells were determined. HCC stem cells, successfully sorted from Hep3B and Huh7 cells, were transfected with short hairpin or overexpression plasmids for HOXA11-AS or HOXA11 overexpression and depletion, with an aim to study the influences of these mediators on the self-renewal, proliferation, migration, and tumorigenicity of HCC stem cells in vivo. Additionally, the potential relationship and the regulatory mechanisms that link HOXA11-AS, HOXA11, and the Wnt signaling pathway were explored through treatment with Dickkopf-1 (a Wnt signaling pathway inhibitor). HCC stem cells showed high expression of HOXA11-AS and low expression of HOXA11. Both HOXA11-AS silencing and HOXA11 overexpression suppressed the self-renewal, proliferation, migration, and tumorigenicity of HCC stem cells in vivo, as evidenced by the decreased expression of cancer stem cell surface markers (CD133 and CD44) and stemness-related transcription factors (Nanog, Sox2, and Oct4). Moreover, silencing HOXA11-AS inactivated the Wnt signaling pathway by decreasing the methylation level of the HOXA11 promoter, thereby inhibiting HCC stem cell characteristics. Collectively, this study suggested that HOXA11-AS silencing exerts an antitumor effect, suppressing HCC development via Wnt signaling pathway inactivation by decreasing the methylation level of the HOXA11 promoter.

scholarly journals Modulation of Calretinin Expression in Human Mesothelioma Cells Reveals the Implication of the FAK and Wnt Signaling Pathways in Conferring Chemoresistance towards Cisplatin

2019 ◽  
Vol 20 (21) ◽  
pp. 5391 ◽  
Author(s):  
Wörthmüller ◽  
Salicio ◽  
Oberson ◽  
Blum ◽  
Schwaller
Keyword(s):  
Wnt Signaling ◽  
Signaling Pathways ◽  
Signaling Pathway ◽  
Expression System ◽  
Single Agent ◽  
Wnt Signaling Pathway ◽  
Tumor Formation ◽  
Mesenchymal Transition

Malignant mesothelioma (MM) is an aggressive asbestos-linked neoplasm, characterized by dysregulation of signaling pathways. Due to intrinsic or acquired chemoresistance, MM treatment options remain limited. Calretinin is a Ca2+-binding protein expressed during MM tumorigenesis that activates the FAK signaling pathway, promoting invasion and epithelial-to-mesenchymal transition. Constitutive calretinin downregulation decreases MM cells’ growth and survival, and impairs tumor formation in vivo. In order to evaluate early molecular events occurring during calretinin downregulation, we generated a tightly controlled IPTG-inducible expression system to modulate calretinin levels in vitro. Calretinin downregulation significantly reduced viability and proliferation of MM cells, attenuated FAK signaling and reduced the invasive phenotype of surviving cells. Importantly, surviving cells showed a higher resistance to cisplatin due to increased Wnt signaling. This resistance was abrogated by the Wnt signaling pathway inhibitor 3289-8625. In various MM cell lines and regardless of calretinin expression levels, blocking of FAK signaling activated the Wnt signaling pathway and vice versa. Thus, blocking both pathways had the strongest impact on MM cell proliferation and survival. Chemoresistance mechanisms in MM cells have resulted in a failure of single-agent therapies. Targeting of multiple components of key signaling pathways, including Wnt signaling, might be the future method-of-choice to treat MM.

scholarly journals Amygdala-Based Altered miRNome and Epigenetic Contribution of miR-128-3p in Conferring Susceptibility to Depression-Like Behavior via Wnt Signaling

2020 ◽  
Vol 23 (3) ◽  
pp. 165-177 ◽  
Author(s):  
Bhaskar Roy ◽  
Michael Dunbar ◽  
Juhee Agrawal ◽  
Lauren Allen ◽  
Yogesh Dwivedi
Keyword(s):  
Wnt Signaling ◽  
Target Genes ◽  
Rna Binding ◽  
Statistical Significance ◽  
Neuroblastoma Cell ◽  
Wnt Signaling Pathway ◽  
Target Prediction ◽  
In Vivo Model

Abstract Background Recent studies suggest that microRNAs (miRNAs) can participate in depression pathogenesis by altering a host of genes that are critical in corticolimbic functioning. The present study focuses on examining whether alterations in the miRNA network in the amygdala are associated with susceptibility or resiliency to develop depression-like behavior in rats. Methods Amygdala-specific altered miRNA transcriptomics were determined in a rat depression model following next-generation sequencing method. Target prediction analyses (cis- and trans) and qPCR-based assays were performed to decipher the functional role of altered miRNAs. miRNA-specific target interaction was determined using in vitro transfection assay in neuroblastoma cell line. miRNA-specific findings from the rat in vivo model were further replicated in postmortem amygdala of major depressive disorder (MDD) subjects. Results Changes in miRNome identified 17 significantly upregulated and 8 significantly downregulated miRNAs in amygdala of learned helpless (LH) compared with nonlearned helpless rats. Prediction analysis showed that the majority of the upregulated miRNAs had target genes enriched for the Wnt signaling pathway. Among altered miRNAs, upregulated miR-128-3p was identified as a top hit based on statistical significance and magnitude of change in LH rats. Target validation showed significant downregulation of Wnt signaling genes in amygdala of LH rats. A discernable increase in expression of amygdalar miR-128-3p along with significant downregulation of key target genes from Wnt signaling (WNT5B, DVL, and LEF1) was noted in MDD subjects. Overexpression of miR-128-3p in a cellular model lead to a marked decrease in the expression of Dvl1 and Lef1 genes, confirming them as validated targets of miR-128-3p. Additional evidence suggested that the amygdala-specific diminished expression of transcriptional repressor Snai1 could be potentially linked to induced miR-128-2 expression in LH rats. Furthermore, an amygdala-specific posttranscriptional switching mechanism could be active between miR-128-3p and RNA binding protein Arpp21 to gain control over their target genes such as Lef1. Conclusion Our study suggests that in amygdala a specific set of miRNAs may play an important role in depression susceptibility, which could potentially be mediated through Wnt signaling.

AML Survival and In Vivo Progression Is Dependent On β-Catenin Signaling.

Blood ◽  
2009 ◽  
Vol 114 (22) ◽  
pp. 2398-2398
Author(s):  
Elena K Siapati ◽  
Magda Papadaki ◽  
Zoi Kozaou ◽  
Erasmia Rouka ◽  
Evridiki Michali ◽  
...  
Keyword(s):  
Bone Marrow ◽  
Wnt Signaling ◽  
Signaling Pathway ◽  
Cell Lines ◽  
Wnt Signaling Pathway ◽  
Canonical Wnt Signaling ◽  
Down Regulation ◽  
Canonical Wnt

Abstract Abstract 2398 Poster Board II-375 B-catenin is the central effector molecule of the canonical wnt signaling pathway which governs cell fate and differentiation during embryogenesis as well as self-renewal of hematopoietic stem cells. Deregulation of the pathway has been observed in various malignancies including myeloid leukemias where over-expression of β-catenin is an independent adverse prognostic factor. In the present study we examined the functional outcome of stable β-catenin down-regulation through lentivirus-mediated expression of short hairpin RNA (shRNA). Reduction of the β-catenin levels in AML cell lines and patient samples diminished their in vitro proliferation ability without significantly affecting cell viability. In order to study the role of β-catenin in vivo, we transplanted leukemic cell lines with control or reduced levels of β-catenin in NOD/SCID animals and analyzed the engraftment levels in the bone marrow. We observed that while the immediate homing of the cells was not affected by the β-catenin levels, the bone marrow engraftment was directly dependent on its levels. Subsequent examination of bone marrow sections revealed that the reduced engraftment was partly due to the inability of the cells with lower β-catenin levels to dock to the endosteal niches, a finding that was confirmed in competitive repopulation assays with untransduced cells. When we examined the expression levels of adhesion molecules and integrins in engrafted cells in vivo, we observed a significant down-regulation of CD44 expression, a molecule that participates in the interaction of HSCs with the niche. Gene expression analysis of the components of the wnt signaling pathway showed that the pathway is subject to tight transcriptional regulation with minor expression deviations. We did, however, observe an up-regulation in components that participate in the non-canonical wnt signaling pathways such as the WNT5B ligand. Ongoing experiments in normal cord blood CD34+ cells will determine the in vivo role of β-catenin signaling in normal hematopoietic progenitors. In conclusion, our study showed that β-catenin comprises an integral part in the development and progression of AML in vivo, indicating that manipulation of the wnt pathway may hold a therapeutic potential in the management of AML. Disclosures: No relevant conflicts of interest to declare.

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