Chromatin dynamics and gene expression profiles during cranial bone regeneration in Xenopus tropicalis

The goal of this study was to identify chromatin regions that are specifically open during Xenopus tropicalis cranial bone regeneration. ATAC-Seq and RNA-Seq data were obtained and compared between two developing and two regenerating skeletal tissues. Regarding skeletal development, we used (i) osteogenic mesenchyme obtained from a thin membrane located between the skin and the brain in stage NF50 tadpoles and (ii), uncultured native osteoblasts freshly extracted from the fully developed frontoparietal bone (calvaria) of stage NF60 tadpoles. Regarding skeletal regeneration, we used (i) the early regeneration plug (non-mineralized and mainly consisting of blood vessels and mesenchymal cells) obtained from the injured cranial region 5 days after it was damaged with a 500 micrometre drill and (ii), the late regeneration plug obtained from the injured cranial region 15 days after it was damaged with a 500 micrometre drill. This plug is covered by a thin layer of regenerated bone. As cranial bone regeneration has mainly been studied in mammalian models, this work is relevant to better understand this process in a broader variety of organisms. By crossing ATAC-seq to RNA-seq data, we identify key genetic regulators of early and late bone regeneration.