Project description:TCF7L1 is a member of the T cell factor/Lymphoid enhancer factor (TCF/LEF) family of tran-scription factors that are part of the WNT/beta-CATENIN signaling pathway. TCF7L1 modulates transcription by interacting with other regulators on chromatin. TCF7L1 has been shown to be one of the key factors in maintaining pluripotency in human embryonic stem cells (ESCs). We previously demonstrated that the absence of TCF71 causes H9 hESCs to differentiate sponta-neously (Sierra et al., 2018 Development 145(4).pii:dev161075). Mechanistically, how TCF7L1 inhibits differentiation and keeps cells in the pluripotent state is not clear. Identifying transcrip-tional regulators on chromatin is a critical step to elucidating one of several molecular mecha-nisms controlled by TCF7L1. We previously developed a FLAG tagged TCF7L1 transgene that is controlled by a doxycycline-inducible TET-ON system and generated the H9-TCF7L1 line (Sier-ra et al., 2018 Development 145(4).pii:dev161075). Here we used the H9-TCF7L1 line and em-ployed the method called rapid immunoprecipitation (IP) mass spectrometry of endogenous pro-tein (RIME) (Mohammed et al., 2016 Nat Protoc 11(2):316-26) to identify TCF7L1-associated proteins on chromatin. Coupling of these two methods (the FLAG tagged TETON inducible sys-tem and RIME) allowed us to control the level of TCF7L1 expression in hESCs, immunopreci-pate TCF7L1 using an anti-FLAG antibody and capture TCF7L1-bound associated complexes on chromatin. Our MS analysis identified some known proteins that have been shown to associate with the WNT/beta-CATENIN/TCF/LEF pathway, as well as novel complexes that have not been linked with TCF7L1. Gene Ontology analysis suggest these proteins function in chromatin modi-fication, splicing, and RNA processing. Our data could create new ideas for in-depth studies of TCF7L1 controlling pluripotency in human ESCs and for understanding how TCF7L1 may act in other cell types.
Project description:Here we show through genome-wide binding studies that transcription factor 7-like 1 (TCF7L1) represses structure-related genes during adipogenesis. Intriguingly, TCF7L1 is induced in a cell contact-dependent manner by confluency in preadipocytes and is required for adipocyte differentiation by repressing transcription of cell structure genes. TCF7L1 is also sufficient to bestow adipogenic potential upon non-adipogenic cells. These results implicate TCF7L1 as a novel adipogenic competency factor that uniquely determines adipogenic fate through cell structure organization required for adipocyte gene activation. Examination of TCF7L1 binding in preadipocytes treated for 24 hours with adipogenic stimuli.
Project description:Here we show through genome-wide binding studies that transcription factor 7-like 1 (TCF7L1) represses structure-related genes during adipogenesis. Intriguingly, TCF7L1 is induced in a cell contact-dependent manner by confluency in preadipocytes and is required for adipocyte differentiation by repressing transcription of cell structure genes. TCF7L1 is also sufficient to bestow adipogenic potential upon non-adipogenic cells. These results implicate TCF7L1 as a novel adipogenic competency factor that uniquely determines adipogenic fate through cell structure organization required for adipocyte gene activation.
Project description:Dysregulation of the canonical Wnt/β-catenin signaling pathway is a hallmark of colorectal cancer (CRC). The T-cell factor/lymphoid enhancer factor (TCF/LEF; hereafter, TCF) family of transcription factors are critical regulators of canonical Wnt/β-catenin target gene expression. Despite similarity across DNA-binding and protein-binding domains, TCF family members differentially regulate target gene expression in CRC. Of the four TCF family members, TCF7L1 predominantly functions as a transcriptional repressor and it has an oncogenic role in CRC. Despite this role, few target genes regulated by TCF7L1 in CRC have been identified. Through RNA-sequencing of transcripts differentially expressed in control and TCF7L1-overexpressing HCT116 cells, we identified 397 genes that were repressed directly, or indirectly, by TCF7L1. Gene set enrichment analysis found genes associated with epithelial-mesenchymal transition amongst those that are differentially expressed. By silencing and overexpressing TCF7L1 in CRC cell lines, we found that TCF7L1 promoted migration, invasion, and adhesion in vitro. Chromatin immunoprecipitation followed by sequencing (ChIP-sequencing) localized 3661 TCF7L1 binding sites within the CRC genome. Comparison of genes whose expression was downregulated by TCF7L1 and genes with TCF7L1 binding sites revealed 41 novel targets directly regulated by TCF7L1. Among these, we localized a TCF7L1 promoter-proximal binding site within the growth arrest specific 1 (GAS1) gene. We found that ectopic GAS1 expression rescued the TCF7L1-mediated increase in migration and invasion in CRC cells. These findings uncover a novel role for TCF7L1 in repressing GAS1 expression to promote migration and invasion of CRC cells in vitro.
Project description:Dysregulation of the canonical Wnt/β-catenin signaling pathway is a hallmark of colorectal cancer (CRC). The T-cell factor/lymphoid enhancer factor (TCF/LEF; hereafter, TCF) family of transcription factors are critical regulators of canonical Wnt/β-catenin target gene expression. Despite similarity across DNA-binding and protein-binding domains, TCF family members differentially regulate target gene expression in CRC. Of the four TCF family members, TCF7L1 predominantly functions as a transcriptional repressor and it has an oncogenic role in CRC. Despite this role, few target genes regulated by TCF7L1 in CRC have been identified. Through RNA-sequencing of transcripts differentially expressed in control and TCF7L1-overexpressing HCT116 cells, we identified 397 genes that were repressed directly, or indirectly, by TCF7L1. Gene set enrichment analysis found genes associated with epithelial-mesenchymal transition amongst those that are differentially expressed. By silencing and overexpressing TCF7L1 in CRC cell lines, we found that TCF7L1 promoted migration, invasion, and adhesion in vitro. Chromatin immunoprecipitation followed by sequencing (ChIP-sequencing) localized 3661 TCF7L1 binding sites within the CRC genome. Comparison of genes whose expression was downregulated by TCF7L1 and genes with TCF7L1 binding sites revealed 41 novel targets directly regulated by TCF7L1. Among these, we localized a TCF7L1 promoter-proximal binding site within the growth arrest specific 1 (GAS1) gene. We found that ectopic GAS1 expression rescued the TCF7L1-mediated increase in migration and invasion in CRC cells. These findings uncover a novel role for TCF7L1 in repressing GAS1 expression to promote migration and invasion of CRC cells in vitro.
Project description:RNAi mediated depletion of TCF7L1 increases activity of a Wnt-based reporter and imparts more aggressive tumor phenotypes in vitro in pancreatic cancer cell lines that express TCF7L1. We sought to determine what changes in transcription ocurred after RNAi mediated knockdown of TCF7L1 in these cells by RNA-sequencing
Project description:To study the functions of Tcf7l1 during gut development, we have ablated Tcf7l1 specifically in the intestinal epithelium using Shh-Cre. To determine transcriptional changes upon loss of Tcf7l1, we have isolated EpCAM-positive epithelial cells from mouse embryos using fluorescence activated cell sorting (FACS) and performed RNA-sequencing analysis.
Project description:The T-cell factor/lymphoid enhancer factor (TCF/LEF) family protein Tcf7l1 is highly abundant in embryonic stem cells (ESCs), regulating pluripotency and preparing epiblasts for further differentiation. Defects in the cardiovascular system in Tcf7l1-null mouse were considered secondary to mesoderm malformation. Here, we used temporally controlled Tcf7l1 expression in Tcf7l1-null ESCs to address whether Tcf7l1 directly contributes to cardiac forward programming. Tcf7l1 knockout during differentiation impaired cardiomyocyte formation but did not affect mesoderm formation. Tcf7l1-null ESCs showed delay in mesoderm formation, but once completed, ectopic Tcf7l1 augmented cardiomyocyte differentiation. Further, Tcf7l1-VP16 and Tcf7l1dN showed procardiac activity whereas Tcf7l1-En was ineffective. Our results support that Tcf7l1 contributes to cardiac lineage development as a ?-catenin-independent transactivator of cardiac genes.