Loss of TJP1 disrupts gastrulation patterning and increases differentiation toward the germ cell lineage in human pluripotent stem cells

Biological patterning events that occur early in development establish proper tissue morphogenesis. Identi-fying the mechanisms that guide these patterning events is necessary in order to understand the molecular drivers of development and disease and to build tissues in vitro. In this study, we use an in vitro model of gastrulation to study the role of tight junctions and apical/basolateral polarity in modulating bone morpho-genic protein-4 (BMP4) signaling and gastrulation-associated patterning in colonies of human pluripotent stem cells (hPSCs). Disrupting tight junctions via knockdown (KD) of the scaffolding tight junction protein-1 (TJP1, also known as ZO1) allows BMP4 to robustly and ubiquitously activate pSMAD1/5 signaling over time, resulting in loss of the patterning phenotype and marked differentiation bias of pluripotent stem cells to primordial germ cell-like cells (PGCLCs). These findings give important insights into how signaling events are regulated and lead to spatial emergence of diverse cell types in vitro.

Automated summary

In this study, an in vitro model of gastrulation is used to investigate the role of tight junctions and apical/basolateral polarity in modulating BMP4 signaling and patterning in colonies of hPSCs. It is found that disrupting tight junctions allows BMP4 to activate pSMAD1/5 signaling, leading to loss of patterning phenotype and biased differentiation of pluripotent stem cells to PGCLCs. These findings provide insights into the regulation of signaling events and spatial emergence of cell types in vitro.