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Beta-Catenin/TCF/LEF regulate expression of the short form human Cripto-1.

ABSTRACT: The human gene Teratocarcinoma-derived growth factor 1 (TDGF1)/Cripto-1/CR-1 which is expressed in a wide variety of human carcinomas is a member of the EGF-cripto FRL1 cryptic (EGF-CFC) gene family. A majority of human colorectal tumors and hepatomas are known to possess a constitutively active canonical Wnt/beta-catenin/TCF signaling pathway, also express CR-1. Expression of a short form of CR-1 mRNA in colon carcinoma and hepatoma cell lines suggests that there may be differential regulation of CR-1 expression by the canonical Wnt signaling pathway in colon cancer as well as hepatoma cell lines. The present study demonstrates a direct transcriptional regulation of the short form CR-1 expression by the canonical Wnt signaling pathway through an intronic-exonic enhancer element, containing three tandem TCF/LEF binding sites within the CR-1 gene.

SUBMITTER: Hamada S

PROVIDER: S-EPMC1853279 | biostudies-literature | 2007 Mar

REPOSITORIES: biostudies-literature

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beta-Catenin/TCF/LEF regulate expression of the short form human Cripto-1.

Hamada Shin S Watanabe Kazuhide K Hirota Morihisa M Bianco Caterina C Strizzi Luigi L Mancino Mario M Gonzales Monica M Salomon David S DS

Biochemical and biophysical research communications 20070202 1

The human gene Teratocarcinoma-derived growth factor 1 (TDGF1)/Cripto-1/CR-1 which is expressed in a wide variety of human carcinomas is a member of the EGF-cripto FRL1 cryptic (EGF-CFC) gene family. A majority of human colorectal tumors and hepatomas are known to possess a constitutively active canonical Wnt/beta-catenin/TCF signaling pathway, also express CR-1. Expression of a short form of CR-1 mRNA in colon carcinoma and hepatoma cell lines suggests that there may be differential regulation ...[more]

PMID: 17291450

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Project description:BackgroundThe Wnt/β-catenin signaling pathway is a prolific regulator of cell-to-cell communication and gene expression. Canonical Wnt/β-catenin signaling involves partnering of β-catenin with members of the TCF/LEF family of transcription factors (TCF1, TCF3, TCF4, LEF1) to regulate gene expression. IL-6 is a key cytokine involved in inflammation and is particularly a hallmark of inflammation in the brain. Astrocytes, specialized glial cells in the brain, secrete IL-6. How astrocytes regulate IL-6 expression is not entirely clear, although in other cells NFκB and C/EBP pathways play a role. We evaluated here the interface between β-catenin, TCFs/LEF and C/EBP and NF-κB in relation to IL-6 gene regulation in astrocytes.MethodsWe performed molecular loss and/or gain of function studies of β-catenin, TCF/LEF, NFκB, and C/EBP to assess IL-6 regulation in human astrocytes. Specifically, siRNA mediated target gene knockdown, cDNA over expression of target gene, and pharmacological agents for regulation of target proteins were used. IL-6 levels was evaluated by real time quantitative PCR and ELISA. We also cloned the IL-6 promoter under a firefly luciferase reporter and used bioinformatics, site directed mutagenesis, and chromatin immunoprecipitation to probe the interaction between β-catenin/TCFs/LEFs and IL-6 promoter activity.Resultsβ-catenin binds to TCF/LEF to inhibits IL-6 while TCFs/LEF induce IL-6 transcription through interaction with ATF-2/SMADs. β-catenin independent of TCFs/LEF positively regulates C/EBP and NF-κB, which in turn activate IL-6 expression. The IL-6 promoter has two putative regions for TCFs/LEF binding, a proximal site located at -91 nt and a distal site at -948 nt from the transcription start site, both required for TCF/LEF induction of IL-6 independent of β-catenin.ConclusionIL-6 regulation in human astrocytes engages a discordant interaction between β-catenin and TCF/LEF. These findings are intriguing given that no role for β-catenin nor TCFs/LEF to date is associated with IL-6 regulation and suggest that β-catenin expression in astrocytes is a critical regulator of anti-inflammatory responses and its disruption can potentially mediate persistent neuroinflammation. Video Abstract.

Project description:The canonical Wnt signaling pathway is mediated by interaction of β-catenin with the T-cell factor/lymphoid enhancer-binding factor (TCF/LEF) transcription factors and subsequent transcription activation of Wnt-target genes. In the hematopoietic system, the function of the pathway has been mainly investigated by rather unspecific genetic manipulations of β-catenin that yielded contradictory results. Here, we used a mouse expressing a truncated dominant negative form of the human TCF4 transcription factor (dnTCF4) that specifically abrogates β-catenin-TCF/LEF interaction. Disruption of the β-catenin-TCF/LEF interaction resulted in the accumulation of immature cells and reduced granulocytic differentiation. Mechanistically, dnTCF4 progenitors exhibited downregulation of the Csf3r gene, reduced granulocyte colony-stimulating factor (G-CSF) receptor levels, attenuation of downstream Stat3 phosphorylation after G-CSF treatment, and impaired G-CSF-mediated differentiation. Chromatin immunoprecipitation assays confirmed direct binding of TCF/LEF factors to the promoter and putative enhancer regions of CSF3R. Inhibition of β-catenin signaling compromised activation of the emergency granulopoiesis program, which requires maintenance and expansion of myeloid progenitors. Consequently, dnTCF4 mice were more susceptible to Candida albicans infection and more sensitive to 5-fluorouracil-induced granulocytic regeneration. Importantly, genetic and chemical inhibition of β-catenin-TCF/LEF signaling in human CD34+ cells reduced granulocytic differentiation, whereas its activation enhanced myelopoiesis. Altogether, our data indicate that the β-catenin-TCF/LEF complex directly regulates G-CSF receptor levels, and consequently controls proper differentiation of myeloid progenitors into granulocytes in steady-state and emergency granulopoiesis. Our results uncover a role for the β-catenin signaling pathway in fine tuning the granulocytic production, opening venues for clinical intervention that require enhanced or reduced production of neutrophils.

Project description:Early in cancer development, tumour cells express vascular endothelial growth factor (VEGF), a secreted molecule that is important in all stages of angiogenesis, an essential process that provides nutrients and oxygen to the nascent tumor and thereby enhances tumor-cell survival and facilitates growth. Survivin, another protein involved in angiogenesis, is strongly expressed in most human cancers, where it promotes tumor survival by reducing apoptosis as well as favoring endothelial cell proliferation and migration. The mechanisms by which cancer cells induce VEGF expression and angiogenesis upon survivin up-regulation remain to be fully established. Since the PI3K/Akt signalling and ?-catenin-Tcf/Lef dependent transcription have been implicated in the expression of many cancer-related genes, including survivin and VEGF, we evaluated whether survivin may favor VEGF expression, release from tumor cells and induction of angiogenesis in a PI3K/Akt-?-catenin-Tcf/Lef-dependent manner. Here, we provide evidence linking survivin expression in tumor cells to increased ?-catenin protein levels, ?-catenin-Tcf/Lef transcriptional activity and expression of several target genes of this pathway, including survivin and VEGF, which accumulates in the culture medium. Alternatively, survivin downregulation reduced ?-catenin protein levels and ?-catenin-Tcf/Lef transcriptional activity. Also, using inhibitors of PI3K and the expression of dominant negative Akt, we show that survivin acts upstream in an amplification loop to promote VEGF expression. Moreover, survivin knock-down in B16F10 murine melanoma cells diminished the number of blood vessels and reduced VEGF expression in tumors formed in C57BL/6 mice. Finally, in the chick chorioallantoid membrane assay, survivin expression in tumor cells enhanced VEGF liberation and blood vessel formation. Importantly, the presence of neutralizing anti-VEGF antibodies precluded survivin-enhanced angiogenesis in this assay. These findings provide evidence for the existance of a posititve feedback loop connecting survivin expression in tumor cells to PI3K/Akt enhanced ?-catenin-Tcf/Lef-dependent transcription followed by secretion of VEGF and angiogenesis.

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Beta-Catenin/TCF/LEF regulate expression of the short form human Cripto-1.

Publications

beta-Catenin/TCF/LEF regulate expression of the short form human Cripto-1.

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