The cytoskeleton modulates the shape of the nucleus of embryonic stem cells and influences OCT4 dynamics

OSES CAMILA; PAULA VERNERI; JUAN JOSE ROMERO; CECILIA DE ROSSI; CAMILA VAZQUEZ ECHEGARAY ; MARCOS FRANCIA; ALEJANDRA GUBERMAN; VALERIA LEVI

virtual

Simposio; The 2nd Crick Beddington Developmental Biology Symposium; 2022

Cells are constantly exposed to mechanical forces that propagate to their interior triggering downstream responses. The cytoskeleton, a network of interconnected biopolymers and crosslinker molecules in constant remodeling, is a key component in transmitting mechanical cues to the nucleus. This relation is particularly relevant in embryonic stem (ES) cells since forces can regulate cell fate and guide developmental processes. However, the organization of the cytoskeleton in ES cells is poorly described and its role in mechanical communication remains elusive. We used fluorescence microscopy methods to study the three-dimensional organization of the cytoskeleton in live ES cells and analyzed if these filaments affect the nucleus. We described that the microtubules present a complex organization extending throughout the cytoplasm and may be involved in cell-cell communication of ES cells. Also, actin concentrates at cell-cell boundaries and cell-substrate contacts whereas vimentin filaments concentrate around the nucleus forming knots and ring-like structures.Moreover, we used fluorescence correlation spectroscopy to explore if the cytoskeleton components can modulate the dynamical organization of OCT4, a key pluripotency transcription factor. We showed that actin depolymerization triggers OCT4 binding to chromatin sites whereas vimentin disruption produces its detachment.Taken together, our results suggest a relevant role of the cytoskeleton network in shaping the nucleus of ES cells and modulating OCT4-DNA interactions which could lead to changes in cell fate decisions.