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

本研究旨在鉴定热带爪蟾（Xenopus tropicalis）颅骨再生过程中特异性开放的染色质区域。研究获取并比较了两份发育阶段骨骼组织与两份再生阶段骨骼组织的ATAC测序（ATAC-Seq）与RNA测序（RNA-Seq）数据。针对骨骼发育过程，我们采集了两类样本：① 取自NF50期蝌蚪皮肤与脑组织间薄层膜的成骨间充质；② 从NF60期蝌蚪完全发育的额顶骨（颅盖骨）中新鲜提取的未培养原生成骨细胞。针对骨骼再生过程，我们同样采集了两类样本：① 经500微米钻头钻孔损伤后5天，从受损颅骨区域获取的早期再生栓（未矿化，主要由血管与间充质细胞构成）；② 经500微米钻头钻孔损伤后15天，从受损颅骨区域获取的晚期再生栓，该栓体表面覆盖有薄层再生骨组织。鉴于颅骨再生的研究多集中于哺乳动物模型，本研究可为在更广泛的生物类群中解析该过程提供重要参考。通过联合分析ATAC测序与RNA测序数据，我们鉴定出了调控骨早期与晚期再生的关键遗传调节因子。