engleski

The efect of dBigH1, embrionic variant of Drosophila melanogaster histone H1, on nuclear reprogramming

It is known that differentiated cells can be reprogrammed when exposed to an oocyte or an embryonic extract. In this work, we followed early reprogramming events in S2 cells treated with DREX (Drosophila early-embryo extract), and complemented this data with results obtained from S2 cells overexpressing dBigH1, together with in vitro chromatin reconstitutions using the same extract. We have observed that a simultaneous loss of somatic H1 linker histone is not necessary for the chromatin incorporation of the embrionic linker histone dBigH1. Observed decreasement in H3K4me3, H3 acetylation and changes in transcription are in correlation with previosly known information of dBigH1 being transcriptional repressor in early embryogenesis. Decrease in the number of HP1a foci in extract-incubated nuclei reflects reorganization of heterochromatin during the reprogramming process. We have also shown that dBigH1 incorporation into chromatin is ATP-facilitated. The affects of depletion dNAP-1 and dNLP histone chaperons and Acf1 subunit of the ACF chromatin remodeler have shown that dNAP-1 has a significant role in chaperoning not only dBigH1 but also H1 in this reprogramming system. The combined approach of the three systems has shown to be useful tool to follow the changes in the epigenetic landscape and in nuclear processes connected to the presence of the embrionic linker histone.

histone variant; dBigH1; embrionic extract; chromatin; nuclear reprogramming

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