Biology subjects

Jauregi-Miguel, A.

Publications and source records attributed to Jauregi-Miguel, A..

4 recordsLinked to original sources

bioRxiv2023

The Developmental Transcription Factor TBX3 Physically Engages with the Wnt/β-catenin Transcriptional Complex in Human Colorectal Cancer Cells to Regulate Metastasis Genes

Wnt signaling orchestrates gene expression in a plethora of processes during development and adult cell homeostasis via the action of nuclear {beta}-catenin. Furthermore, neoplasia of the colorectal epithelium begins with aberrant Wnt/{beta}-catenin signaling. Yet, little is known about how {beta}-catenin generates context-specific transcriptional outcomes. We have previously identified the developmental transcription factor TBX3 as a tissue-specific component of the Wnt/{beta}-catenin nuclear complex during mouse forelimb development. In this study, we show that TBX3 is present and functionally active in human colorectal cancers. TBX3s genomic binding pattern suggests a regulatory role that broadly coincides with that of Wnt/{beta}-catenin. Moreover, proteomics proximity labelling indicated that, during Wnt pathway activation, TBX3 is vicinal to several protein partners, including the transcription factors TCF/LEF and chromatin remodeling complexes which are usually found at Wnt responsive elements. Sequence and structure analysis revealed that TBX3 possesses an exposed Asp-Pro-Phe (NPF) motif predicted by AlphaFold2 Multimer to mediate direct interactions with several Wnt-activated TBX3 partners. Deletion of NPF abrogates TBX3 proximity to these partners and its ability to modulate Wnt-dependent transcription. TBX3 emerges as a key modulator of the oncogenic activity of Wnt/{beta}-catenin in colorectal cancer, and its mechanism of action exposes a novel druggable protein-interaction surface.

developmental biology↗

bioRxiv2023

Single-cell response to Wnt activation in human embryonic stem cells reveals uncoupling of Wnt target gene expression

Wnt signaling drives nuclear translocation of {beta}-catenin and its subsequent association with the DNA-bound TCF/LEF transcription factors, which dictate target gene specificity by recognizing Wnt responsive elements across the genome. {beta}-catenin target genes are therefore thought to be collectively activated upon Wnt pathway stimulation. However, this appears in contrast with the non-overlapping patterns of Wnt target gene expression in several contexts, including early mammalian embryogenesis. Here we followed Wnt target gene expression in human embryonic stem cells after Wnt pathway stimulation at a single-cell resolution. Cells changed gene expression program over time consistent with three key developmental events: i) loss of pluripotency, ii) induction of Wnt target genes, and iii) mesoderm specification. Contrary to our expectation, not all cells displayed equal amplitude of Wnt target gene activation; rather, they distributed in a continuum from strong to weak responders when ranked based on the expression of the target AXIN2. Moreover, high AXIN2 did not always correspond to elevated expression of other Wnt targets, which were activated in different proportions in individual cells. This uncoupling of Wnt target gene expression, which was also identified in single colorectal cancer cells with hyper-activated Wnt signaling, underlines the necessity to identify additional mechanisms that explain the heterogeneity of the Wnt/{beta}-catenin-mediated transcriptional outputs in single cells.

developmental biology↗

bioRxiv2022

Time-resolved analysis of Wnt-signaling reveals β-catenin temporal genomic repositioning and cell type-specific plastic or elastic chromatin responses

Wnt signaling orchestrates gene expression via its effector {beta}-catenin. Whether {beta}-catenin targets genomic regions simultaneously or in a temporal fashion, and how this impacts the chromatin dynamics to modulate cell behavior, is currently unknown. Here we find that {beta}-catenin binds different loci at each time-point after stimulation, implying that the definition of Wnt-targets is fundamentally temporal. This process is intrinsically cell-type specific. In fact, Wnt/{beta}-catenin progressively shapes the chromatin of human embryonic stem cells consistent with their mesodermal differentiation: we call this genomic response plastic. In embryonic kidney cells, on the other hand, Wnt/{beta}-catenin drives a transient chromatin opening, followed by a re-establishment of the pre-stimulation state: a response that we define elastic. Finally, the Wnt-induced transient chromatin opening requires {beta}-catenin, suggesting a previously unappreciated pioneering role for this molecule. We submit that the plastic-vs-elastic behavior constitutes part of the mechanism explaining how Wnt/{beta}-catenin drives divergent cell-fate decisions during development and homeostasis.

genomics↗

bioRxiv2020

TBX3 acts as tissue-specific component of the Wnt/β-catenin enhanceosome

BCL9 and PYGO are {beta}-catenin cofactors that enhance the transcription of Wnt target genes. They have been proposed as therapeutic targets to diminish Wnt signalling output in intestinal malignancies. Here we find that, in colorectal cancer cells and in developing mouse forelimbs, BCL9 proteins sustain the action of {beta}-catenin in a largely PYGO-independent manner. Our genetic analyses implied that BCL9 necessitates other interaction partners in mediating its transcriptional output. We identified the transcription factor TBX3 as a candidate tissue-specific member of the {beta}-catenin transcriptional complex. In developing forelimbs, TBX3 and BCL9 co-occupy a large number of Wnt-responsive regulatory elements, genome-wide. Moreover, mutations in Bcl9 affect the expression of TBX3 targets in vivo, and modulation of TBX3 abundance impacts on Wnt target genes transcription in a {beta}-catenin- and TCF/LEF-dependent manner. Finally, TBX3 overexpression exacerbates the metastatic potential of Wnt-dependent human colorectal cancer cells. Our work implicates TBX3 as a new, context-dependent component of the Wnt/{beta}-catenin-dependent enhanceosome.

developmental biology↗