Nanoscale organization of epigenomic compartments during human neuronal differentiation from induced pluripotent stem cells

CARDOZO GIZZI, ANDRES M.; REMEDI, MONICA; GASTALDI, LAURA; CACERES, ALFREDO

Cordoba

Jornada; IV Jornadas Avances en Medicina Traslacional IUCBC.; 2023

Instituto Universitario de Ciencias BIomedicas de Córdoba

During the course of differentiation, neural progenitors must turn on and off a different set ofgenes to accomplish a change in cellular phenotype. This is believe to occur thanks tochanges in the epigenomic landscape. Moreover, there is a functional relationship betweenthe epigenetic modifications on chromatin and its 3D nuclear organization.Here, we used a human model of neural development derived from stem cells to study howchromatin post-translational modifications change during differentiation. A non-supervisedmultiparametric analysis, UMAP, was conducted on microscopy images to separate thedifferent populations in the cell culture. It was found that human neurons are characterizedby an intense H3K27me3 mark (associated to the Polycomb repressive complex), whereasneural progenitors have relative low levels. Remarkably, Ezh2, the most active enzymeresponsible of the deposition of the mark, is markedly down-regulated as cells progresses toneurons. This lead us to question the role of Ezh2 in neurons.Both by expansion and STED microscopy we were able to see in single-cells at thenanoscale the domain organization of H3K27me3 and H3K4me3 (active promoters).H3K27me3 chromatin nanodomains appeared at both precursors and neurons, with thelatter being characterized by a population of bigger and with higher intensity compartmentsthat the ones present in precursors. This initial characterization of the human model lays theground to study how chromatin spatial organization is required as an additional layer of geneexpression regulation.