Trimethylation of histone H3K76 by Dot1B enhances cell cycle progression after mitosis in Trypanosoma cruzi

• Published in: Biochimica et biophysica acta. Molecular cell research 2020-07, Vol.1867 (7), p.118694-118694, Article 118694
• Main Authors: Nunes, Vinicius Santana, Moretti, Nilmar Silvio, da Silva, Marcelo Santos, Elias, Maria Carolina, Janzen, Christian J., Schenkman, Sergio
• Format: Article
• Language: English
• Subjects: Cell cycle; Checkpoint; Dot1; Histone; Mitosis; Trypanosoma cruzi
• ISSN: 0167-4889; 1879-2596
• DOI: 10.1016/j.bbamcr.2020.118694

Dot1 enzymes are histone methyltransferases that mono-, di- and trimethylate lysine 79 of histone H3 to affect several nuclear processes. The functions of these different methylation states are still largely unknown. Trypanosomes, which are flagellated protozoa that cause several parasitic diseases, have two Dot1 homologues. Dot1A catalyzes the mono- and dimethylation of lysine 76 during late G2 and mitosis, and Dot1B catalyzes trimethylation, which is a modification found in all stages of the cell cycle. Here, we generated Trypanosoma cruzi lines lacking Dot1B. Deletion of one allele resulted in parasites with increased levels of mono- and dimethylation and a reduction in H3K76me3. In the full knockout (DKO), no trimethylation was observed. Both the DKO and the single knockout (SKO) showed aberrant morphology and decreased growth due to cell cycle arrest after G2. This phenotype could be rescued by caffeine in the DKO, as caffeine is a checkpoint inhibitor of the cell cycle. The knockouts also phosphorylated γH2A without producing extensive DNA breaks, and Dot1B-depleted cells were more susceptible to general checkpoint kinase inhibitors, suggesting that a lack of H3K76 trimethylation prevents the initiation and/or completion of cytokinesis. [Display omitted] •T. cruzi contains two Dot1 enzymes (Dot1A and B) that mono-, di- and trimethylate lysine 76 of histone H3, acting in mitosis.•Trimethylation is reduced and dimethylation predominates after depleting Dot1B in T. cruzi, delaying the exit of mitosis.•KO cells present high level of H2A-phosphorylated histone through activation of checkpoint kinases that affect cytokinesis.•Covering the dimethylation of the histone H3 is important to complete the cell cycle after mitosis.