Regulation of transcription factor SP1 by β-catenin destruction complex modulates Wnt response

AbstractThe ubiquitous transcription factor Specificity protein 1 (SP1) is heavily modified post-translationally. These modifications are critical for switching its functions and modulation of its transcriptional activity, DNA-binding and stability. However the mechanism governing the stability of SP1 by cellular signaling pathways is not well understood. Here, we provide biochemical and functional evidences that SP1 is an integral part of the Wnt signaling pathway. We identified a phosphodegron motif in SP1 that is specific to mammals. In absence of Wnt signaling, GSK3β kinase mediated phosphorylation and β-TrCP E3 ubiquitin ligase mediated ubiquitination is required to induce SP1 degradation. When Wnt signaling is on, SP1 is stabilized in β-catenin-dependent manner. SP1 directly interacts with β-catenin and Wnt signaling induces the stabilization of SP1 by impeding its interaction with β-TrCP and AXIN1, components of the destruction complex. Wnt signaling suppresses ubiquitination and subsequent proteosomal degradation of SP1. Furthermore, SP1 regulates Wnt-dependent stability of β-catenin and their mutual stabilization is critical for target gene expression, suggesting a feedback mechanism. Upon stabilization SP1 and β-catenin co-occupy the promoters of TCFL2/β-catenin target genes. Collectively, this study uncovers a direct link between SP1 and β-catenin in Wnt signaling pathway.

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Regulation of Transcription Factor SP1 by the β-Catenin Destruction Complex Modulates Wnt Response

Molecular and Cellular Biology ◽

10.1128/mcb.00188-18 ◽

2018 ◽

Vol 38 (22) ◽

Cited By ~ 5

Author(s):

Rafeeq Mir ◽

Ankita Sharma ◽

Saurabh J. Pradhan ◽

Sanjeev Galande

Keyword(s):

Transcription Factor ◽

Wnt Signaling ◽

Signaling Pathway ◽

Target Genes ◽

Glycogen Synthase ◽

Wnt Signaling Pathway ◽

Feedback Mechanism ◽

Regulation Of Transcription ◽

Dependent Manner ◽

Factor Specificity

ABSTRACT The ubiquitous transcription factor specificity protein 1 (SP1) is heavily modified posttranslationally. These modifications are critical for switching its functions and modulation of its transcriptional activity and DNA binding and stability. However, the mechanism governing the stability of SP1 by cellular signaling pathways is not well understood. Here, we provide biochemical and functional evidence that SP1 is an integral part of the Wnt signaling pathway. We identified a phosphodegron motif in SP1 that is specific to mammals. In the absence of Wnt signaling, glycogen synthase kinase 3β (GSK3β)-mediated phosphorylation and β-TrCP E3 ubiquitin ligase-mediated ubiquitination are required to induce SP1 degradation. When Wnt signaling is on, SP1 is stabilized in a β-catenin-dependent manner. SP1 directly interacts with β-catenin, and Wnt signaling induces the stabilization of SP1 by impeding its interaction with β-TrCP and axin1, components of the destruction complex. Wnt signaling suppresses ubiquitination and subsequent proteosomal degradation of SP1. Furthermore, SP1 regulates Wnt-dependent stability of β-catenin and their mutual stabilization is critical for target gene expression, suggesting a feedback mechanism. Upon stabilization, SP1 and β-catenin cooccupy the promoters of TCFL2/β-catenin target genes. Collectively, this study uncovers a direct link between SP1 and β-catenin in the Wnt signaling pathway.

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The Microphthalmia-Associated Transcription Factor Mitf Interacts with β-Catenin To Determine Target Gene Expression

Molecular and Cellular Biology ◽

10.1128/mcb.02299-05 ◽

2006 ◽

Vol 26 (23) ◽

pp. 8914-8927 ◽

Cited By ~ 108

Author(s):

Alexander Schepsky ◽

Katja Bruser ◽

Gunnar J. Gunnarsson ◽

Jane Goodall ◽

Jón H. Hallsson ◽

...

Keyword(s):

Gene Expression ◽

Transcription Factor ◽

Wnt Signaling ◽

Signaling Pathway ◽

Critical Role ◽

Wnt Signaling Pathway ◽

Feedback Mechanism ◽

Canonical Wnt Signaling ◽

Melanocyte Stem Cells ◽

Canonical Wnt

ABSTRACT Commitment to the melanocyte lineage is characterized by the onset of expression of the microphthalmia-associated transcription factor (Mitf). This transcription factor plays a fundamental role in melanocyte development and maintenance and seems to be crucial for the survival of malignant melanocytes. Furthermore, Mitf has been shown to be involved in cell cycle regulation and to play important functions in self-renewal and maintenance of melanocyte stem cells. Although little is known about how Mitf regulates these various processes, one possibility is that Mitf interacts with other regulators. Here we show that Mitf can interact directly with β-catenin, the key mediator of the canonical Wnt signaling pathway. The Wnt signaling pathway plays a critical role in melanocyte development and is intimately involved in triggering melanocyte stem cell proliferation. Significantly, constitutive activation of this pathway is a feature of a number of cancers including malignant melanoma. Here we show that Mitf can redirect β-catenin transcriptional activity away from canonical Wnt signaling-regulated genes toward Mitf-specific target promoters to activate transcription. Thus, by a feedback mechanism, Mitf can diversify the output of canonical Wnt signaling to enhance the repertoire of genes regulated by β-catenin. Our results reveal a novel mechanism by which Wnt signaling and β-catenin activate gene expression, with significant implications for our understanding of both melanocyte development and melanoma.

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Loading-related Regulation of Transcription Factor EGR2/Krox-20 in Bone Cells Is ERK1/2 Protein-mediated and Prostaglandin, Wnt Signaling Pathway-, and Insulin-like Growth Factor-I Axis-dependent

Journal of Biological Chemistry ◽

10.1074/jbc.m111.252742 ◽

2011 ◽

Vol 287 (6) ◽

pp. 3946-3962 ◽

Cited By ~ 29

Author(s):

Gul Zaman ◽

Andrew Sunters ◽

Gabriel L. Galea ◽

Behzad Javaheri ◽

Leanne K. Saxon ◽

...

Keyword(s):

Transcription Factor ◽

Growth Factor ◽

Wnt Signaling ◽

Signaling Pathway ◽

Bone Cells ◽

Wnt Signaling Pathway ◽

Regulation Of Transcription ◽

Insulin Like Growth Factor ◽

Factor I ◽

Growth Factor I

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Regulation of Wnt Signaling through Ubiquitination and Deubiquitination in Cancers

International Journal of Molecular Sciences ◽

10.3390/ijms21113904 ◽

2020 ◽

Vol 21 (11) ◽

pp. 3904 ◽

Cited By ~ 3

Author(s):

Hong-Beom Park ◽

Ju-Won Kim ◽

Kwang-Hyun Baek

Keyword(s):

Wnt Signaling ◽

Signaling Pathway ◽

Cell Polarity ◽

Target Genes ◽

Wnt Signaling Pathway ◽

Therapeutic Strategies ◽

Deubiquitinating Enzymes ◽

Post Translational Modifications ◽

The Stability ◽

Pigmentation Disorders

The Wnt signaling pathway plays important roles in embryonic development, homeostatic processes, cell differentiation, cell polarity, cell proliferation, and cell migration via the β-catenin binding of Wnt target genes. Dysregulation of Wnt signaling is associated with various diseases such as cancer, aging, Alzheimer’s disease, metabolic disease, and pigmentation disorders. Numerous studies entailing the Wnt signaling pathway have been conducted for various cancers. Diverse signaling factors mediate the up- or down-regulation of Wnt signaling through post-translational modifications (PTMs), and aberrant regulation is associated with several different malignancies in humans. Of the numerous PTMs involved, most Wnt signaling factors are regulated by ubiquitination and deubiquitination. Ubiquitination by E3 ligase attaches ubiquitins to target proteins and usually induces proteasomal degradation of Wnt signaling factors such as β-catenin, Axin, GSK3, and Dvl. Conversely, deubiquitination induced by the deubiquitinating enzymes (DUBs) detaches the ubiquitins and modulates the stability of signaling factors. In this review, we discuss the effects of ubiquitination and deubiquitination on the Wnt signaling pathway, and the inhibitors of DUBs that can be applied for cancer therapeutic strategies.

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

Genes & Development ◽

10.1101/gad.14.14.1741 ◽

2000 ◽

Vol 14 (14) ◽

pp. 1741-1749 ◽

Cited By ~ 1

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.

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

Proceedings of the National Academy of Sciences ◽

10.1073/pnas.0807763105 ◽

2008 ◽

Vol 105 (40) ◽

pp. 15417-15422 ◽

Cited By ~ 130

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.

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GPX8 is transcriptionally regulated by FOXC1 and promotes the growth of gastric cancer cells through activating the Wnt signaling pathway

Cancer Cell International ◽

10.1186/s12935-020-01692-z ◽

2020 ◽

Vol 20 (1) ◽

Author(s):

Hong Chen ◽

Lu Xu ◽

Zhi-li Shan ◽

Shu Chen ◽

Hao Hu

Keyword(s):

Gastric Cancer ◽

Transcription Factor ◽

Western Blot ◽

Wnt Signaling ◽

Cancer Cells ◽

Signaling Pathway ◽

Wnt Signaling Pathway ◽

Migration And Invasion ◽

Gastric Cancer Cells ◽

Cancer Tissues

Abstract Background Glutathione Peroxidase 8 (GPX8) as a member of the glutathione peroxidase (GPx) family plays an important role in anti-oxidation. Besides, dysregulation of GPX8 has been found in gastric cancer, but its detailed molecular mechanism in gastric cancer has not been reported. Methods Our study detected the expression of GPX8 in gastric cancer tissues and cell lines using immunohistochemistry (IHC), western blot and qRT-PCR, and determined the effect of GPX8 on gastric cancer cells using CCK-8, colony formation, transwell migration and invasion assays. Besides, the effect of GPX8 on the Wnt signaling pathway was determined by western blot. Furthermore, the transcription factor of GPX8 was identified by bioinformatics methods, dual luciferase reporter and chromatin immunoprecipitation (CHIP) assays. In addition, the effect of GPX8 on tumor formation was measured by IHC and western blot. Results The over-expression of GPX8 was observed in gastric cancer tissues and cells, which facilitated the proliferation, migration and invasion of gastric cancer cells as well as the tumor growth. GPX8 knockdown effectively inhibited the growth of gastric cancer cells and tumors. Moreover, GPX8 could activate the Wnt signaling pathway to promote the cellular proliferation, migration and invasion through. Furthermore, FOXC1 was identified as a transcription factor of GPX8 and mediated GPX8 expression to affect cell development processes. Conclusions These findings contribute to understanding the molecular mechanism of GPX8 in gastric cancer. Additionally, GPX8 can be a potential biomarker for gastric cancer therapy.

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miR-34c-5p and CaMKII are involved in aldosterone-induced fibrosis in kidney collecting duct cells

AJP Renal Physiology ◽

10.1152/ajprenal.00358.2017 ◽

2018 ◽

Vol 314 (3) ◽

pp. F329-F342 ◽

Cited By ~ 11

Author(s):

Eui-Jung Park ◽

Hyun Jun Jung ◽

Hyo-Jung Choi ◽

Jeong-In Cho ◽

Hye-Jeong Park ◽

...

Keyword(s):

Protein Expression ◽

Wnt Signaling ◽

Signaling Pathway ◽

Target Genes ◽

Collecting Duct ◽

Wnt Signaling Pathway ◽

Putative Target ◽

Duct Cells ◽

Collecting Duct Cells ◽

In Cells

Mineralocorticoids trigger a profibrotic process in the kidney. In mouse cortical collecting duct cells, the present study addressed two main questions: 1) what are microRNAs (miRNAs) and their target genes that are changed by aldosterone? and 2) what do miRNAs, in response to aldosterone, regulate regarding signaling pathways related to fibrosis? A microarray chip assay was done in cells in the absence or presence of aldosterone treatment (10−6M; 3 days). The candidate miRNAs were identified by the criteria of >30% of fold change among the significantly changed miRNAs ( P < 0.05). Twenty-nine miRNAs were upregulated (>1.3-fold), and 27 miRNAs were downregulated (<0.7-fold). Putative target genes of identified miRNAs were associated with 74 Kyoto Encyclopedia of Genes and Genomes pathways. Among them, the wingless-related integration site (Wnt) signaling pathway was highly ranked, where 15 mature miRNAs were observed. These miRNAs were further analyzed by real-time quantitative PCR, and among them, miR-130b-3p, miR-34c-5p, and miR-146a-5p were selected. Through the identification of putative target genes of these three miRNAs, mRNA and protein expression of the Ca2+/calmodulin-dependent protein kinase type II β-chain ( Camk2b) gene (a target gene of miR-34c-5p) were found to be increased significantly in aldosterone-treated cells, where fibronectin (FN) and α-smooth muscle actin were induced. When CaMKIIβ small interfering RNA or the miR-34c-5p mimic was transfected, aldosterone-induced FN expression was significantly attenuated, along with reduced CaMKIIβ protein expression. A luciferase reporter assay revealed a decrease of CaMKIIβ translation in cells transfected with miRNA mimics of miR-34c-5p. In conclusion, aldosterone-induced downregulation of miR-34c-5p in the Wnt signaling pathway and a consequent increase of CaMKIIβ expression are likely to be involved in aldosterone-induced fibrosis.

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