Transcriptional activation of mouse major satellite regions during neuronal differentiation.

Recent studies have revealed various biological functions for repetitive sequences, which make up about half of the human genome. One such sequence, major satellites, which are tandem repetitive sequences adjacent to the centromere, have been shown to be a kinetochore component that plays a role in the formation and function of the pericentric heterochromatin necessary for mitosis. However, it is unknown whether these regions also play a role in post-mitotic cells. Here, we show that, during neuronal differentiation, the heterochromatin domains that include major satellite regions become both enriched with the active histone modification lysine-4 trimethylation of histone H3, and more sensitive to nuclease, both of which suggest increased activation of this area. Further supporting this notion, we also found that transcription from major satellite regions is significantly increased during neuronal differentiation both in vitro and in vivo. These results together suggest that the structural and transcriptional state of major satellite regions changes dramatically during neuronal differentiation, implying that this region might play a role in differentiating neurons.