Pluripotency is the ability of cells to adopt any cellular identity of the adult organism. To reach their final identity as a differentiated cell, genetic, epigenetic, and metabolic regulations are essential. However, significantly less is understood of the role of cell biology in the establishment and execution of pluripotency.
The internal structure of a cell is directed by its microtubule cytoskeleton, a framework that assists in signalling and organelle trafficking, as well as bestowing cellular identity. To explore the link between the microtubule cytoskeleton and pluripotency, we used cutting-edge live imaging technologies on human induced pluripotent stem cells (hiPSCs).
We discovered that following the transition to primed pluripotency, pluripotent cells in vitro utilise a non-centrosomal CAMSAP3-dependent microtubule organisation. High temporal resolution imaging demonstrated the directional growth of microtubules from an apical CAMSAP3 cap to the basal region of the cell. Despite the similarity to naïve pluripotent cells in utilising CAMSAP3, the microtubule organisation of primed hiPSCs differs in its widespread apical localisation and molecular composition, suggesting a signature of a more differentiated state. Trilineage differentiation of hiPSCs induced a switch from non-centrosomal to centrosomal microtubule organisation. When comparing genetic lineage markers, CAMSAP3-depleted hiPSCs showed altered expression profiles during differentiation.
Uncovering the dynamics of cellular architecture in pluripotent cells using live imaging may allow us to better manipulate hiPSCs, and shed light on the fundamental cell biological differences between pluripotent stages.