RT Journal Article
SR Electronic
T1 TCF7L1 and TCF7 differentially regulate specific mouse ES cell genes in response to GSK-3 inhibition
JF bioRxiv
FD Cold Spring Harbor Laboratory
SP 473801
DO 10.1101/473801
A1 Steven Moreira
A1 Caleb Seo
A1 Enio Polena
A1 Sujeivan Mahendram
A1 Eloi Mercier
A1 Alexandre Blais
A1 Bradley W. Doble
YR 2018
UL http://biorxiv.org/content/early/2018/11/21/473801.abstract
AB The genome-wide chromatin occupancy of the TCF/LEF factors and its modulation by Wnt pathway activation remain poorly defined. Here, we describe mouse ES cell (mESC) lines expressing a single copy knock-in of the 3xFLAG epitope at the N-terminus of TCF7L1 and TCF7, the two most-highly expressed TCF/LEF factors in mESCs. TCF7L1 protein levels, detected by immunoblotting with a FLAG antibody, were much higher than TCF7 in mESCs maintained in standard serum- and LIF-supplemented medium, even in the presence of the GSK-3 inhibitor, CHIR99021 (CHIR). We used FLAG antibody-mediated ChIP-seq to determine TCF7 and TCF7L1 chromatin occupancy in mESCs cultured in standard medium with or without CHIR for 14 hours. TCF7 and TCF7L1 displayed very few overlapping ChIP peaks across the genome, with TCF7L1 binding significantly more genes than TCF7 in both culture conditions. Despite a reduction in total TCF7L1 protein after CHIR treatment, the TCF7L1 ChIP peak profiles were not uniformly attenuated. Our data demonstrate that TCF7L1 chromatin occupancy upon short-term CHIR treatment is modulated in a target-specific manner. Our findings also suggest that Wnt target genes in mESCs are not regulated by TCF/LEF switching, and TCF7L1, although often called a constitutive repressor, may serve as a transcriptional activator of certain target genes in CHIR-treated mESCs.HighlightsChIP and cytometry data suggest that TCF7L1 does not directly regulate mESC Nanog expression.TCF7L1 remains associated with β-catenin in the presence of CHIR99021.TCF7 and TCF7L1 display different chromatin occupancies in mESCs.TCF7L1 binding at specific genomic sites is variably altered by CHIR99021.