Biology subjects

Theeuwes, B.

Publications and source records attributed to Theeuwes, B..

4 recordsLinked to original sources

bioRxiv2024

STAT3 signalling enhances tissue expansion during postimplantation mouse development

STAT3 signalling has been studied extensively in the context of self-renewal and differentiation of mouse embryonic stem cells. Zygotic STAT3 is required for normal postimplantation development. On an outbred genetic background, Stat3 null embryos consistently lagged behind their littermates, beginning with significant reduction of epiblast cells at implantation. Remarkably, mutants closely resemble non-affected embryos from the previous day at all postimplantation stages examined. We pinpoint this phenotype to loss of the serine-phosphorylated form of STAT3 which predominates in postimplantation embryonic tissues. Bulk RNA-sequencing analysis of isolated mouse epiblasts confirmed Stat3 null embryos exhibited developmental delay transcriptionally. Single cell RNA sequencing of mid gestation chimaeras containing STAT3 null embryonic stem cells revealed exclusion of mutant cells exclusively from the erythroid lineage. Although Stat3 null embryonic stem cells can differentiate into erythroid and hematopoietic lineages in vitro, they are out-competed when mixed with wild type cells. Combined with the reduced size of STAT3 null epiblasts after implantation, our results implicate a role for STAT3 in cell proliferation affecting temporal control of embryonic progression and rapid differentiation. For the purpose of Open Access, the author has applied a CC BY public copyright licence to any Author Accepted Manuscript version arising from this submission.

developmental biology↗

bioRxiv2024

Axin1 and Axin2 regulate the WNT-signaling landscape to promote distinct mesoderm programs

How distinct mesodermal lineages - extraembryonic, lateral, intermediate, paraxial and axial - are specified from pluripotent epiblast during gastrulation is a longstanding open question. By investigating AXIN, a negative regulator of the WNT/{beta}-catenin pathway, we have uncovered new roles for WNT signaling in the determination of mesodermal fates. We undertook complementary approaches to dissect the role of WNT signaling that augmented a detailed analysis of Axin1;Axin2 mutant mouse embryos, including single-cell and single-embryo transcriptomics, with in vitro pluripotent Epiblast-Like Cell differentiation assays. This strategy allowed us to reveal two layers of regulation. First, WNT initiates differentiation of primitive streak cells into mesoderm progenitors, and thereafter, WNT amplifies and cooperates with BMP/pSMAD1/5/9 or NODAL/pSMAD2/3 to propel differentiating mesoderm progenitors into either posterior streak derivatives or anterior streak derivatives, respectively. We propose that Axin1 and Axin2 prevent aberrant differentiation of pluripotent epiblast cells into mesoderm by spatially and temporally regulating WNT signaling levels.

developmental biology↗

bioRxiv2024

Eomes directs the formation of spatially and functionally diverse extra-embryonic hematovascular tissues

During mouse gastrulation, extraembryonic mesoderm (ExEM) contributes to the extraembryonic yolk sac (YS) and allantois, both of which are essential for successful gestation. Although the genetic networks coordinating intra-embryonic mesodermal subtype specification are well-studied, the mechanisms driving ExEM diversification are poorly understood. Here, we reveal that embryoid body in vitro differentiation generates two distinct lineages of mesodermal cells matching YS and allantois respectively. Combining in vitro models with in vivo chimeric embryo analysis, we discover that Eomesodermin (Eomes) regulates the formation of a subset of YS-fated ExEM but is dispensable for allantois formation. Furthermore, simultaneous disruption of Eomes and T impedes the specification of any YS or allantois mesoderm, indicating compensatory roles for T during allantois formation when Eomes is disrupted. Our study highlights previously unrecognized functional and mechanistic diversity in ExEM diversification and endothelial development and introduces a tractable EB model to dissect the signaling pathways and transcriptional networks driving the formation of key extraembryonic tissues.

developmental biology↗

bioRxiv2022

Rabbit Development as a Model for Single Cell Comparative Genomics

Biomedical research relies heavily on the use of model organisms to gain insight into human health and development. Traditionally, the mouse has been the favored vertebrate model, due to its experimental and genetic tractability. Non-rodent embryological studies however highlight that many aspects of early mouse development, including the egg-cylinder topology of the embryo and its method of implantation, diverge from other mammals, thus complicating inferences about human development. In this study, we constructed a morphological and molecular atlas of rabbit development, which like the human embryo, develops as a flat-bilaminar disc. We report transcriptional and chromatin accessibility profiles of almost 180,000 single cells and high-resolution histology sections from embryos spanning gastrulation, implantation, amniogenesis, and early organogenesis. Using a novel computational pipeline, we compare the transcriptional landscape of rabbit and mouse at the scale of the entire organism, revealing that extra-embryonic tissues, as well as gut and PGC cell types, are highly divergent between species. Focusing on these extra-embryonic tissues, which are highly accessible in the rabbit, we characterize the gene regulatory programs underlying trophoblast differentiation and identify novel signaling interactions involving the yolk sac mesothelium during hematopoiesis. Finally, we demonstrate how the combination of both rabbit and mouse atlases can be leveraged to extract new biological insights from sparse macaque and human data. The datasets and analysis pipelines reported here set a framework for a broader cross-species approach to decipher early mammalian development, and are readily adaptable to deploy single cell comparative genomics more broadly across biomedical research.

developmental biology↗