Analysis of the interplay between MeCP2 and histone H1 during <i>in vitro</i> differentiation of human ReNCell neural progenitor cells

An immortalized neural cell line derived from the human ventral mesencephalon, called ReNCell, and its MeCP2 knock out were used. With it, we characterized the chromatin compositional transitions undergone during differentiation, with special emphasis on linker histones. While the WT cells displayed the development of dendrites and axons the KO cells did not, despite undergoing differentiation as monitored by NeuN. ReNCell expressed minimal amounts of histone H1.0 and their linker histone complement consisted mainly of histone H1.2, H1.4 and H1.5. The overall level of histone H1 exhibited a trend to increase during the differentiation of MeCP2 KO cells. The phosphorylation levels of histone H1 proteins decreased dramatically during ReNCell's cell differentiation independently of the presence of MeCP2. Immunofluorescence analysis showed that MeCP2 exhibits an extensive co-localization with linker histones. Interestingly, the average size of the nucleus decreased during differentiation but in the MeCP2 KO cells, the smaller size of the nuclei at the start of differentiation increased by almost 40% after differentiation by 8 days (8 DIV). In summary, our data provide a compelling perspective on the dynamic changes of H1 histones during neural differentiation, coupled with the intricate interplay between H1 variants and MeCP2.