Cytoskeleton structure and role in stem cells and mouse embryos

VAZQUEZ ECHEGARAY C; GUBERMAN A; LEVI V; ROMERO J.; BRUNO L.

Congreso; Reunion Conjunta de Biociencias; 2017

The cytoskeleton is a complex network of interlinking polymericfilaments, which is fundamental in cellular mechanics. It has beensuggested that active cytoskeleton forces could regulate chroma-tin organization and dynamics, and indirectly gene expression. Wepropose to study how these networks can respond and transmit me-chanical signals to the cell nuclei during cellular differentiation andearly embryo development. As a first step, we studied cytoskeletonorganization in mouse embryonic stem cells (mESC).W4 mESCs were transfected with GFP-tagged actin, α-tubulinor vimentin and H2B-mCherry to label the chromatin. We obtained3D confocal images to get insight into the organization of the diffe-rent networks and combined fluorescence correlation spectroscopy(FCS) and fluorescence recovery after photobleaching (FRAP) ex-periments to study their dynamics. In contrast to the typical star-likeordered networks in differentiated, adherent cells, in mESCs thecytoskeleton filaments do not seem to form a well-defined network,instead it is much more relaxed, affecting the viscoelastic propertiesof the cytoplasm (1). Complementary, FCS and FRAP experimentsshowed that the dynamics of GFP-tagged tubulin and vimentin fo-llows an anomalous diffusion model in µs - ms time scale.These results show that cytoskeleton has different structures instem and differentiated cells, and open the possibility to study itsevolution during cell differentiation process