Biology subjects

Geens, M.

Publications and source records attributed to Geens, M..

4 recordsLinked to original sources

bioRxiv2021

Gains of 12p13.31 delay WNT-mediated initiation of hPSC differentiation and promote residual pluripotency in a cell cycle dependent manner

Though gains of chromosome 12p13.31 are highly recurrent in hPSC, their impact on differentiation is poorly understood. We identify a reduction in differentiation capacity towards all three germ layers and a subpopulation of residual pluripotent cells that appear during hepatic specification. These cells form as a result of the overexpression of NANOG and GDF3, whereby NANOG as the primary driver delays activation of WNT signaling, partly as a result of a direct physical interaction with TCF7. Entry into the residual state is determined by cell cycle position at the onset of differentiation and is maintained by a feedback loop between NANOG and GDF3. These findings highlight the ability of genetically abnormal hPSC to escape correct differentiation and to form residual pluripotent cells, an important risk in the safe clinical translation of hPSC. Our results further refine the molecular mechanisms that underpin the exit from pluripotency and onset of differentiation.

cell biology↗

bioRxiv2020

Endogenous suppression of WNT signalling in human embryonic stem cells leads to low differentiation propensity towards definitive endoderm

SummaryLow differentiation propensity towards a targeted lineage can significantly hamper the utility of individual human pluripotent stem cell (hPSC) lines in biomedical applications. Here, we use monolayer and micropatterned cell cultures, as well as transcriptomic profiling, to investigate how variability in signalling pathway activity between human embryonic stem cell lines affects their differentiation efficiency towards definitive endoderm (DE). We show that endogenous suppression of WNT signalling in hPSCs at the onset of differentiation prevents the switch from self-renewal to DE specification. Gene expression profiling reveals that this inefficient switch is reflected in NANOG expression dynamics. Importantly, we demonstrate that higher WNT stimulation or inhibition of the PI3K/AKT signalling can overcome the DE commitment blockage. Our findings highlight that redirection of the activity of Activin/NODAL pathway by WNT signalling towards mediating DE fate specification is a vulnerable spot, as disruption of this process can result in poor hPSC specification towards DE.Competing Interest StatementThe authors have declared no competing interest.View Full Text

cell biology↗

bioRxiv2020

Constitutional activation of BMP4 and WNT signalling in hESC results in impaired mesendoderm differentiation

We identified a human embryonic stem cell subline that fails to respond to the differentiation cues needed to obtain mesendoderm derivatives, differentiating into trophoblast-like cells instead. RNA-sequencing analysis showed that the subline has hyperactivation of the WNT and BMP4 signalling. Modulation of these pathways with small molecules confirmed them as the cause of the differentiation impairment. While activation of WNT and BMP4 in control cells resulted in a loss of mesendoderm differentiation and induction of trophoblast markers, inhibition of these pathways in the subline restored its ability to differentiate. Karyotyping and exome sequencing analysis did not identify any changes in the genome that could account for the pathway deregulation. These findings add to the increasing evidence that different responses of stem cell lines to differentiation protocols are based on genetic and epigenetic factors, inherent to the line or acquired during cell culture.

cell biology↗

bioRxiv2018

High-throughput micro-patterning platform reveals Nodal-dependent dissection of peri-gastrulation-associated versus pre-neurulation associated fate patterning

In vitro models of post-implantation human development are valuable to the fields of regenerative medicine and developmental biology. Here, we report characterization of a robust in vitro platform that enabled high-content screening of multiple human pluripotent stem cell (hPSC) lines for their ability to undergo peri-gastrulation-like fate patterning upon BMP4 treatment of geometrically-confined colonies and observed significant heterogeneity in their differentiation propensities along a gastrulation associable and neuralization associable axis. This cell line associated heterogeneity was found to be attributable to endogenous nodal expression, with upregulation of Nodal correlated with expression of a gastrulation-associated gene profile, and Nodal downregulation correlated with a neurulation-associated gene profile expression. We harness this knowledge to establish a platform of pre-neurulation-like fate patterning in geometrically confined hPSC colonies that arises due to a stepwise activation of reaction-diffusion and positional-information. Our work identifies a Nodal signalling dependent switch in peri-gastrulation versus pre-neurulation-associated fate patterning in hPSC cells, provides a technology to robustly assay hPSC differentiation outcomes, and suggests conserved mechanisms of self-organized fate specification in differentiating epiblast and ectodermal tissues.

developmental biology↗