52 - Communication libre
Transplantation and regeneration
3 juin 2021, 13:50 - 15:20, Stream 4: Video Invited, SST, SSCViscérale & ARS
Video: Mapping origins of replication in a regenerating liver
N. Dommann1, G. Rossetti2, A. Karamichali2, V. Dionellis2, A. Keogh1, D. Candinas1, T. Halazonetis2, D. Stroka1, Presenter: N. Dommann1 (1Bern, 2Geneva)
DNA replication begins at thousands of individual origins of replication (ORI) that are tightly regulated both spatially and temporally. Timely execution of replication and transcription is important to avoid DNA replication stress and collisions, which could lead to genomic instability and mutagenesis. The aim of this study is to monitor DNA replication and transcription to determine if collisions between replication and transcription occur during the proliferative phase in a regenerating liver.
We synchronized hepatocyte proliferation using two-thirds partial hepatectomy (PHx) in mice. To map early S-phase replication origins, nascent DNA was labelled in vivo with EdU every 2 hours from 24 to 44 hours post resection with and without hydroxyurea (HU), to limit fork progression after origin firing. Edu containing DNA was sequenced from isolated hepatocytes. To label newly transcribed mRNA, EU was injected into mice between 24-40 hours in two hours intervals for 30 minutes before harvesting. EUseq was performed to identify nascent mRNA in vivo.
We were able to map and identify the temporal pattern of ORI in hepatocytes following PHx. Origins were located outside transcribed genes.
For the first time, we could show that in a normal regenerating liver, transcription and translation are synchronized and with no collisions happening between them.