Topoisomerase 1 activity during mitotic transcription favors the transition from mitosis to G1 [SLAM-seq]

Using SLAM-seq to capture de novo synthesized polyadenylated RNAs, we quantitated changes in nascent RNA expression, as well as in total RNA expression. Overall design: SLAM-seq in asynchronous cells and mitotic cells (two different timepoints: mid and late mitosis, 0 and 40 respectively). To enrich mitotic cells, they were blocked in S phase by addition of 2.5mM thymidine (Sigma, T9250) for 19-24h and, after washing with fresh medium, transferred in fresh medium containing 400ng/ml nocodazole (Sigma, M1404) and incubated for ~14h. Mitotic cells were collected and allowed to progress to mid mitotis (0) and late mitosis (40). All experiments were performed in HCT116 and derived cell lines.